U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5162

Prepared in cooperation with the

National Park Service

Occurrence and Distribution of Organic 

Wastewater Compounds in Rock Creek Park, 

Washington, D.C., 2007–08
Cover.  Boulder Bridge, Rock Creek Park, Washington, D.C. [Photograph by National Park Service.]
Occurrence and Distribution of Organic 

Wastewater Compounds in Rock Creek 

Park, Washington, D.C., 2007–08

By Daniel J. Phelan and Cherie V. Miller

Prepared in cooperation with the 

National Park Service 

Scientific Investigations Report 2010–5162

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Phelan, D.J., and Miller, C.V., 2010, Occurrence and distribution of organic wastewater compounds in Rock Creek Park, 

Washington, D.C., 2007–08: U.S. Geological Survey Scientific Investigations Report 2010–5162, 68 p.

ISBN 978-1-4113-2961-4
iii

Contents

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

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

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

Previous Investigations........................................................................................................................3

Rock Creek Basin.........................................................................................................................3

Organic Wastewater Compounds (OWCs) in Streams..........................................................3

Description of Study Area ...................................................................................................................6

Methods of Data Collection .........................................................................................................................6

Thermal Infrared (TIR) Survey and Site Selection ..........................................................................7

Synoptic Water-Quality Sampling......................................................................................................7

Sediment Sampling...............................................................................................................................9

Stormwater-Quality Sampling.............................................................................................................9

Passive Sampling..................................................................................................................................9

Estimation of Ambient Concentrations of Organic Wastewater Compounds from 

Semipermeable Membrane Devices (SPMD) ..................................................................10

Analytical Methods.............................................................................................................................10

Quality Assurance of Data ................................................................................................................10

Water-Quality Data......................................................................................................................................15

Synoptic Water-Quality Data ............................................................................................................15

Dissolved Organic Wastewater Compounds ........................................................................15

Dissolved Pharmaceuticals .....................................................................................................16

Total Organic Wastewater Compounds .................................................................................18

Synoptic Bed-Sediment Data ...........................................................................................................18

Stormwater-Quality Data...................................................................................................................23

Passive-Sampler Data........................................................................................................................27

Semipermeable Membrane Devices (SPMD).......................................................................27

Polar Organic Chemical Integrative Samplers (POCIS) ......................................................27

Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park .................37

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

Acknowledgments.......................................................................................................................................41

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

Appendix A: Selected images from thermal infrared flyover of Rock Creek Park, 

Washington, D.C., at dawn, January 31, 2007............................................................................46

Appendix B: Organic wastewater compounds analyzed in filtered surface-water 

samples from Rock Creek Park, Washington, D.C., June 27–28, 2007...................................48

Appendix C: Organic wastewater compounds for which surface-water samples 

were analyzed in unfiltered water in Rock Creek Park, Washington, D.C., 

June 27–28, 2007.............................................................................................................................49

Appendix D: Organic wastewater compounds for which creek-bottom-sediment 

samples were analyzed in Rock Creek Park, Washington, D.C., 

June 27–28, 2007.............................................................................................................................50

Appendix E: Concentrations of organic wastewater compounds in stormwater 

samples from Rock Creek at Joyce Road, Washington, D.C. 

(station number 01648010), June and September 2008............................................................51

Appendix F: Concentrations of organic wastewater compounds from 

Semipermeable Membrane Devices (SPMD) in Rock Creek Park, 

Washington, D.C., July 2–29, 2008...............................................................................................65

Appendix G: Concentrations of pesticides from Semipermeable Membrane 

Devices (SPMD) in Rock Creek Park, Washington, D.C., July 2–29, 2008...........................67

Figures

1–3. Maps showing—

1. Location of Rock Creek drainage basin and Rock Creek Park 

study area, Washington, D.C..............................................................................................2

2. Locations of surface-water sampling stations within the Rock 

Creek Park study area, Washington, D.C., 2007–08 .......................................................4

3. Generalized location of areas that are served by a combined 

sewer system in Washington, D.C. ...................................................................................7

4–6. Graphs showing—

4. Long-term average discharge and daily mean discharge from 

October 2006 through September 2008 at Rock Creek at 

Sherrill Drive, Rock Creek Park, Washington, D.C. ......................................................16

5. Discharge and sample times from Rock Creek at Joyce Road, 

Washington, D.C., (A) June 27–28, 2008 and (B) September 6–7, 2008.....................24

6. Discharge and concentrations of total organic carbon (TOC), 

suspended sediment, caffeine, and DEET from Rock Creek at 

Joyce Road, Washington, D.C., (A) June 27–28, 2008 and 

(B) September 6, 2008 .......................................................................................................39
v

Tables

1. Station numbers and names, and sample-collection dates for organic 

wastewater compounds from Rock Creek Park, Washington, D.C., 2007–08.....................8

2. Concentrations of total organic carbon, and dissolved organic wastewater 

compounds detected in water from Rock Creek Park, Washington, D.C., 

June 27–28, 2007.........................................................................................................................12

3. Summary of dissolved organic wastewater compounds detected at 

concentrations above method reporting levels in samples from Rock Creek 

Park, June 27–28, 2007...............................................................................................................16

4. Concentrations of dissolved pharmaceuticals in water samples from 

Rock Creek Park, Washington, D.C., June 27–28, 2007 ........................................................17

5. Summary of total organic wastewater compounds detected in water 

samples from Rock Creek Park, during base-flow synoptic, June 27–28, 2007 ...............19

6. Concentrations of total organic wastewater compounds detected in water 

from Rock Creek Park, Washington, D.C., during base-flow synoptic, 

June 27–28, 2007 .........................................................................................................................20

7. Concentrations of organic wastewater compounds detected in creek 

bottom sediment, Rock Creek Park, Washington, D.C., during base-flow 

synoptic, June 27–28, 2007........................................................................................................22

8. Summary of dissolved- and total-organic-wastewater-compound 

concentrations in stormwater samples collected from Rock Creek at 

Joyce Road, Washington, D.C. (station number 01648010), June and 

September 2008...........................................................................................................................25

9. Organic wastewater compounds that were detected in stormwater 

samples at Joyce Road that also were detected at each of the seven 

sediment-sampling sites............................................................................................................27

10. Concentrations of pharmaceuticals and antibiotics in stormwater 

samples collected from Rock Creek at Joyce Road, Washington, D.C., 

June 27 and September 6, 2008................................................................................................28

11. Estimated average water concentrations from the Semipermeable 

Membrane Devices (SPMD) deployed in Rock Creek Park, 

Washington, D.C., July 2 through 29, 2008..............................................................................29

12. Normalized concentrations of organic wastewater compounds and 

pharmaceuticals detected in Polar Organic Chemical Integrative 

Samplers (POCIS) from five sites in Rock Creek Park, Washington, D.C., 

July 2 through 29, 2008...............................................................................................................32

13. Concentrations of pharmaceuticals and antibiotics from Polar Organic 

Chemical Integrative Samplers (POCIS) samples collected at two sites 

in Rock Creek Park, Washington, D.C., July 2 through 29, 2008..........................................36
vi

Conversion Factors and Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

yard (yd) 0.9144 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2

) 0.09290 square meter (m2)

square inch (in2

) 6.452 square centimeter (cm2)

square mile (mi2

) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

cubic foot (ft3

) 0.02832 cubic meter (m3)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

cubic foot per day (ft3

/d) 0.02832 cubic meter per day (m3/d)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

gallon per day (gal/d) 0.003785 cubic meter per day (m3

/d)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F = (1.8 × °C) + 32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

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

25 °C).

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

or micrograms per liter (μg/L).

The term “water year” is defined as the 12-month period from October 1 of any given year 

through September 30 of the following year. The water year is designated by the calendar year 

in which it ends and which includes 9 of the 12 months. Thus, the year ending September 30, 

1999, is called the “1999” water year.


Occurrence and Distribution of Organic 

Wastewater Compounds in Rock Creek Park, 

Washington, D.C., 2007–08

By Daniel J. Phelan and Cherie V. Miller

Abstract 

The U.S. Geological Survey, and the National Park 

Service Police Aviation Group, conducted a high-resolution, 

low-altitude aerial thermal infrared survey of the Washington, 

D.C. section of Rock Creek Basin within the Park boundaries 

to identify specific locations where warm water was discharging from seeps or pipes to the creek. Twenty-three stream sites 

in Rock Creek Park were selected based on the thermal infrared images. Sites were sampled during the summers of 2007 

and 2008 for the analysis of organic wastewater compounds 

to verify potential sources of sewage and other anthropogenic 

wastewater. Two sets of stormwater samples were collected, 

on June 27–28 and September 6, 2008, at the Rock Creek at 

Joyce Road water-quality station using an automated sampler 

that began sampling when a specified stage threshold value 

was exceeded. Passive-sampler devices that accumulate 

organic chemicals over the duration of deployment were 

placed in July 2008 at the five locations that had the greatest 

number of detections of organic wastewater compounds from 

the June 2007 base-flow sampling. 

During the 2007 base-flow synoptic sampling, there were 

ubiquitous low-level detections of dissolved organic wastewater indicator compounds such as DEET, caffeine, HHCB, and 

organophosphate flame retardants at more than half of the 23 

sites sampled in Rock Creek Park. Concentrations of DEET 

and caffeine in the tributaries to Rock Creek were variable, 

but in the main stem of Rock Creek, the concentrations were 

constant throughout the length of the creek, which likely 

reflects a distributed source. Organophosphate flame retardants 

in the main stem of Rock Creek were detected at estimated 

concentrations of 0.2 micrograms per liter or less, and generally did not increase with distance downstream. Overall, 

concentrations of most wastewater indicators in whole-water 

samples in the Park were similar to the concentrations found 

at the upstream sampling station at the Maryland/District 

of Columbia boundary. Polycyclic aromatic hydrocarbons 

were the dominant organic compounds found in the stormwater samples at the Joyce Road station. Polycyclic aromatic 

hydrocarbons were consistently found in higher concentrations either in sediment or in whole-water samples than in the 

dissolved samples collected during base-flow conditions at 

the 23 synoptic sites, or in the Joyce Road station stormwater 

samples. 

Introduction 

Rock Creek Park is located in north-central Washington, 

D.C., and is operated by the National Park Service (NPS) 

(fig. 1). Rock Creek may be affected by a decaying wastewater 

infrastructure that results in contamination from potentially 

leaking sewer lines that are exposed at stream crossings or 

along the banks of Rock Creek and its tributaries, or from 

sewer lines leaking into the local shallow, unconfined groundwater around the creek. A combined sewer system in part of 

Washington, D.C. also contributes sewage to Rock Creek 

when large storms contribute rainfall to the system that can 

overwhelm its capacity, resulting in sanitary-sewer discharges. 

Contamination from sewage sources by any mechanism is 

problematic to the health of the aquatic resources in the river 

and to the safety of local residents and park visitors, and therefore is of concern to the Park staff. In 2006, the 

U.S. Geological Survey (USGS) partnered with the NPS to 

conduct a study to investigate possible hydraulic connections 

between leaky sewer lines and the creek using thermal infrared 

(TIR) techniques to locate seeps, and active and passive waterquality sampling techniques to characterize the seeps that were 

identified. Water samples were collected and analyzed for the 

presence of organic wastewater compounds (OWCs) that can 

indicate the presence of untreated sewage. This is the third 

joint USGS-NPS study to investigate sources of impairment to 

Rock Creek in Washington, D.C.
2 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Figure 1. Location of Rock Creek drainage basin and Rock Creek Park study area, Washington, D.C. 

(from Anderson, 2002).
Introduction 3

Purpose and Scope

The purpose of this report is to describe the results of 

investigations of potentially leaky sewer lines or groundwater 

seeps in Rock Creek Park in Washington, D.C. from January 

2007 through September 2008. The report describes the TIR 

technique used in January 2007 to locate areas where warm 

groundwater was seeping into the creek and identifies their 

origin, such as groundwater seeps, discharging pipelines, 

or leaky pipelines. On the basis of the TIR results, samples 

were collected in June 2007 at 23 sites in the basin and were 

analyzed for OWCs (fig. 2). Five of the sites with the highest 

number of detections of OWCs were selected for monitoring using passive sampling methods over a 4-week period in 

July 2008. Sequential samples were collected over two storm 

cycles in the summer of 2008 at the monitoring site at Joyce 

Road (fig. 2) and analyzed for concentrations of OWCs (antimicrobials, fragrances, surfactants, fire retardants, etc.). 

Previous Investigations

This section describes previous investigations that were 

conducted at both local and national scales. The first section 

describes investigations in the Rock Creek Basin, and the 

second section presents the recent history of national studies 

on OWCs in streams.

Rock Creek Basin

One of the earliest published reports on the water 

quality of Rock Creek was by Sherman and Horner (1935), 

who documented contamination as indicated by biological 

oxygen demand (BOD) and coliform bacteria in the stream 

from the Maryland/Washington, D.C. boundary to the mouth 

at the Potomac River. On the basis of Sherman and Horner’s 

recommendations, improvements to sewer infrastructures 

were instituted, and as documented by CH2M HILL (1977, 

1979), stream conditions have improved, but the stream 

remains affected by contamination. Fecal-indicator bacteria 

and other indicators of sewage contamination persist, particularly in the lower reaches of the stream. In 1979, CH2M HILL 

conducted a survey of undocumented outfalls on the main 

stem and tributaries of Rock Creek, and documented a number 

of these outfalls that were discharging waters with elevated 

levels of fecal coliforms and chemical oxygen demand 

(COD). Concentrations of iron, lead, zinc, and mercury in bed 

sediment also were measured in that survey, but none of those 

concentrations exceeded any action levels for that period. 

The effects of urbanization on streamflow and sediment 

transport in the Rock Creek and Anacostia River Basins of 

Montgomery County, Maryland from 1962–74 were described 

by York and Herb (1978). The USGS collected water- and 

sediment-quality samples and analyzed for pesticides and 

organic compounds within Rock Creek Park during 1999–

2000 (Anderson and others, 2002). In Anderson’s temporal 

assessment of water quality at one site on the main stem of 

Rock Creek, concentrations of four insecticides—chlorpyrifos, 

diazinon, carbaryl, and malathion—were found to exceed published guidelines for the protection of aquatic life year-round. 

Several major classes of chemicals also were found in samples 

of bed sediment from the three locations that were sampled 

on the main stem of Rock Creek. Most of the chemicals and 

compounds analyzed were detected in the bed sediment. 

Concentrations of 8 trace metals, 13 polycyclic aromatic 

hydrocarbons (PAHs), 7 organochlorine (OC) pesticides, total 

polychlorinated biphenyls (PCBs), and 1 phthalate compound 

were found to exceed published guidelines for the protection of aquatic life (U.S. Environmental Protection Agency, 

1999; Canadian Council of Ministers of the Environment, 

2007; International Joint Commission of the Unites States and 

Canada, 1989). Miller and others (2006) described the chemical and ecological health of white sucker, a benthic-feeding 

fish, during 2003–04 in the Rock Creek Basin of Washington, 

D.C., and found anecdotal evidence of contaminant effects on 

the fish. 

Organic Wastewater Compounds (OWCs) in 

Streams

The USGS has pioneered new analytical techniques to 

measure OWCs in aquatic environments. Kolpin and others 

(2002) documented and compared new analytical methods 

and reported results for a reconnaissance of 95 OWCs in 139 

streams across the United States. During 1999 and 2000, 

they focused on sites that were most likely to be influenced 

by upstream sources of wastewater, such as watersheds with 

intense urbanization and livestock production. The compounds 

most frequently detected in their study were coprostanol 

(a fecal steroid), cholesterol (a plant and animal steroid), 

DEET (N,N-Diethyl-meta-toluamide, a broadly used insect 

repellant), caffeine (a stimulant produced in plants grown 

primarily in tropical regions and thus not found naturally in 

temperate zone streams), triclosan (a common antimicrobial 

disinfectant in hand soap and other household products), 

tris(2-chloroethyl)phosphate (a fire retardant), and 4-nonylphenol (a nonionic detergent metabolite). One or more OWCs 

were found in 80 percent of the streams sampled, but few 

concentrations exceeded drinking-water criteria or aquatic-life 

guidelines. Total summed concentrations of the OWCs commonly exceeded 1 μg/L (microgram per liter) and the maximum total concentration was 57.3 μg/L, indicating that further 

study may be needed on the biological and human-health 

effects of mixtures of OWCs in drinking-water sources.

A follow-up study by Kolpin and others (2004) compared 

upstream and downstream concentrations of OWCs at 10 

urban locations in Iowa during low-, normal-, and high-flow 

conditions. Their results indicated that the likely source of 

beta-sitosterol was decaying plant materials (from both natural 

sources and paper products). The anti-convulsive carbamazepine was the most commonly detected pharmaceutical 
4 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Figure 2. Locations of surface-water sampling 

stations within the Rock Creek Park study area, 

Washington, D.C., 2007–08.
Introduction 5

compound, and urban contributions to OWCs at sites in their 

study decreased during higher flows likely due to dilution. 

They found a significant relation between the ratio of population over stream discharge to total concentrations of OWCs, 

indicating that an increase in population per unit of flow corresponded to an increase in the occurrence and concentrations 

of OWCs.

Glassmeyer and others (2005) conducted a study of a 

stream transect that passed by a wastewater-treatment plant 

outfall and found results of the occurrence of OWCs similar 

to those in the earlier studies by Kolpin and others (2002, 

2004). Coprostanol/cholesterol ratios in effluent (0.66) 

and two downstream samples of the wastewater-treatment 

plant (WWTP) (0.55 and 0.48) were similar to those found 

in human fecal material, indicating that this ratio is a good 

indicator of human waste. Flame retardants and fecal and 

plant sterols were the most commonly detected compounds. 

Glassmeyer and others (2005) found that benzophenone, ethyl 

citrate, HHCB (galaxolide), tributyl phosphate, and triclosan 

were indicators of human waste-stream contamination because 

they were scarce or below detection levels upstream from the 

WWTPs, were found in almost all WWTP effluents, and were 

present in lower concentrations in downstream samples. An 

interesting approach in this study was a comparison of the 

ratios of ephemeral (easily degraded) compounds (HHCB and 

ATHN (tonalide), intermediately persistent ones (coprostanol 

and triclosan), and recalcitrant ones (carbamazepine and 

DEET). When ephemeral compounds were compared to more 

persistent compounds, there was a dramatic decrease in the 

ratios moving downstream from the WWTP, providing a further weight of evidence as to their source.

In another national study by USGS (Focazio and others, 

2008), 25 groundwater and 49 surface-water sites that are 

sources of drinking water were sampled for the occurrence of 

100 targeted OWCs. The five most frequently detected chemicals in surface water were cholesterol, metolachlor, cotinine, 

beta-sitosterol, and 1,7-dimethylxanthine, and the five most 

frequently detected chemicals in groundwater were trichloroethene (TCE), carbamazepine, bisphenol-A, 1,7-dimethylxanthine, and tris(2-chloroethyl)phosphate. Carbamazepine 

and DEET are not efficiently removed by commonly used 

wastewater-treatment processes, and carbamazepine was the 

most commonly detected pharmaceutical in both surface water 

and groundwater. Pesticides, fragrances and flavors, steroids, 

non-prescription drugs, plasticizers, flame retardants, and 

detergent metabolites were detected more frequently than 

prescription pharmaceutical compounds. Barnes and others 

(2008) also published results from a national reconnaissance 

of 47 groundwater sites that were susceptible to wastewater 

contamination, testing for 65 OWCs. Their most frequently 

detected compounds were DEET, bisphenol A, tris(2-chloroethyl)phosphate, sulfamethoxazole, and 4-octylphenol monoethoxylate. They observed that, in general, OWCs have a lower 

frequency of occurrence in groundwater than in surface water, 

and the number of detections tends to decrease with increasing 

well depth.

Barber and others (2006) measured inorganic and organic 

stream chemical loading along a land-use gradient in Boulder 

Creek, Colorado, and found that the most abundant OWCs 

were ethylenediaminetetraacetic acid (EDTA), nonylphenolethoxycarboxylic acids (NPEC), and coprostanol. They 

observed a steep increase in coprostanol, triclosan, caffeine, 

and nonylphenol below a WWTP, and found that the concentrations of gadolinium increased with the concentrations 

of OWCs and WWTP discharge. Concentrations of lithium, 

used as a mood stabilizer and for the treatment of bipolar 

disorder, also correlated positively to concentrations of 

OWCs and probably had a medical source. Concentrations of 

OWCs increased along the population and land-use gradients. 

Caffeine was a good indicator of population along the stream 

gradient, but triclosan was only detected in the headwaters and 

just below the WWTP. 

Caffeine, HHCB, and nicotine derivatives have been used 

successfully in many applications as markers of wastewater 

contamination to surface and groundwaters (Buerge and others, 2003, 2006, 2008; Bradley and others, 2007; Weigel and 

others, 2004). The environmental occurrence of caffeine that 

is naturally present in many tropical plant species can largely 

be attributed to human-waste sources in temperate zones. 

Nicotine cannot be exclusively attributed to human waste, 

as it has natural plant sources, largely from the cultivation 

of tobacco in the Southeast and Mid-Atlantic regions of the 

United States. However, cotinine is a metabolite of nicotine 

produced in the mammalian liver, so it is a good indicator 

of wastewater. Bradley and others (2007) used microcosms 

to study the potential biotransformation and degradation of 

cotinine and caffeine in river sediments. They found substantial transformations of these compounds and determined that 

although their presence may be a strong indicator of wastewater sources, their absence cannot be interpreted as a lack of 

these sources.

Phillips and Chalmers (2009) used the occurrence of 

certain groups of chemicals to differentiate between combined sewer overflows (CSOs) and WWTP effluents in urban 

streams. Concentrations of chemicals that are removed or 

degraded in the wastewater-treatment processes (caffeine, 

TCPP, and cholesterol) increase during storm events due 

to CSOs that contribute untreated water during the storm. 

Concentrations of chemicals that are not effectively removed 

in the process are higher in the WWTP effluents and therefore 

are higher during base flow and are diluted during storm 

events. Chemicals that have other sources, such as agricultural pesticides, have maximum concentrations at sites 

distant from WWTP effluents and CSO outfalls. The number of PAHs detected and the concentrations of individual 

PAHs were generally higher in urban streams and related to 

CSO outfalls, probably reflecting contributions from street 

runoff. Concentrations of fluoranthene, methylnaphthalene, 

2,6-dimethylnaphthalene, 2-methylnaphthalene, phenanthrene, 

and pyrene were similar. Other studies have recently directly 

linked urban loadings of PAHs to coal-tar parking-lot sealants, 

showing that this one source is by far the most prevalent in 

urban runoff (Van Metre and Mahler, 2005).
6 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Results from these and other studies have consistently 

found OWCs in many streams across the United States, often 

at locations that are near potential sources, and sometimes 

farther from wastewater influences. The concentrations are 

usually low, but not always. Pharmaceutical compounds are 

detected less frequently than other groups of OWCs, and 

generally are found closer to potential sources. Often multiple compounds are found in each sample, and the biological 

and health effects at ambient concentrations are relatively 

unknown. Many recent studies are focusing on detection 

and concentration behavior of OWCs, as they are processed 

through WWTPs and along stream gradients as well. As the 

chemical properties differ widely among OWCs, presence/

absence and changes in concentrations can be used as tracers of specific sources. Different OWCs can be very specific 

markers of the type of contamination, such as raw or treated 

sewage effluent.

Description of Study Area

The Rock Creek study area (fig. 1) is a heavily urbanized 

basin within the Potomac River Basin. The creek channel 

winds approximately 33 mi (miles) from its source near 

Laytonsville, Maryland, to the Potomac River (CH2M Hill, 

1979). Rock Creek and the Chesapeake and Ohio (C&O) 

Canal converge 0.25 mi upstream from the Potomac River 

(fig. 2). The C&O Canal drains a small part of southern 

Montgomery County, Maryland, and discharges to Rock 

Creek. Therefore, for the purposes of this report, the Rock 

Creek Basin ends at its junction with the C&O Canal. The 

Rock Creek Basin drains approximately 76.5 mi2

 (square 

miles)in both Maryland and Washington, D.C., of which 

approximately 18 mi2

 are within Washington, D.C. The 

NPS manages 2,118 acres within the Rock Creek Basin of 

Washington, D.C. (CH2M Hill, 1979; fig. 1). 

Streamflow in Rock Creek has been measured at a USGS 

streamflow gaging station at Sherrill Drive (station number 

01648000) from October 1929 through the present (2010) 

(fig. 2). The drainage area above the gage is 62.2 mi2

. The 

annual mean discharge at Sherrill Drive from 1930 through 

2008 was 64.3 ft3

/s (cubic feet per second), and ranged from 

a maximum of 142 ft3

/s in 1972 to a minimum of 16.1 ft3/s 

in 1931. Annual mean discharge for the 2007 water year 

(October 1, 2006–September 30, 2007) was 54.4 ft3

/s, and 

annual mean discharge for the 2008 water year (October 1, 

2007–September 30, 2008) was 57.6 ft3

/s (U.S. Geological 

Survey, 2009). Runoff for Rock Creek was only slightly below 

average during the period of this study compared to the period 

of record, and runoff during the 2 years of this investigation 

was similar.

The Rock Creek Basin lies almost entirely within the 

upland section of the Piedmont Physiographic Province. The 

rocks are metamorphosed sedimentary and igneous rocks of 

Cambrian to Ordovician age that have been intensely folded 

and deformed so that there is negligible intergranular porosity 

(Duigon and others, 2000). The primary types of bedrock in 

the basin are complex schists, tonalites, and granodiorites 

(Darton, 1950). The most detailed geologic investigation of 

the Rock Creek Basin in Washington, D.C. is by Fleming and 

others (1994).

Washington, D.C. is supplied with drinking water by 

the U.S. Army Corps of Engineers Washington Aqueduct, 

which withdraws water from the Potomac River. Many of the 

areas of Montgomery County in the Rock Creek Basin are 

supplied with water by the Washington Suburban Sanitary 

Commission (WSSC), which withdraws water from both the 

Potomac and Patuxent Rivers (fig. 1). There are no major 

water withdrawals from the Rock Creek Basin; however, there 

are small users, homeowners, and farms that use private wells 

for supplies in the northern reaches of the basin in Maryland. 

There are no WWTPs in the Rock Creek Basin in either 

Montgomery County or Washington, D.C.; however, some 

areas in Montgomery County are served by small or privately 

owned septic systems. Even though there are no public water 

withdrawals from the basin, or public-treated wastewater 

discharges to the basin, there is an unmeasureable net gain 

of water from outside the basin because all public water used 

in the basin is supplied from outside the basin. Not all of the 

water delivered to the basin discharges to the public wastewater systems (due to lawn watering, car washing, fire hydrant 

use, and leaky water and sewer lines).

About one third of the 60-mi2

 area of Washington, D.C. 

is served by a combined sewer system (CSS) that routes both 

rainwater and municipal sewage through the same pipes to the 

Blue Plains Wastewater Treatment Plant (fig. 3). When flow 

exceeds the maximum capacity of the CSS during storms, 

untreated wastewater discharges from the CSS to the creeks 

that eventually drain to the Potomac and Anacostia Rivers 

(District of Columbia Water and Sewer Authority, 2002). 

These releases or discharges are called CSOs and they can 

affect Rock Creek Park.

There are two flood-control reservoirs in the basin—Lake 

Needwood on Rock Creek, and Lake Bernard Frank on the 

North Branch of Rock Creek (fig. 1)—that have acted as sediment and nutrient traps since their construction in the 1960s 

(Duigon and others, 2000; Maryland-National Capital Park 

and Planning Commission, 1999). Both of these reservoirs are 

located in Montgomery County. Further information on the 

geology, hydrology, precipitation, and land-use patterns in the 

study area is given in Anderson and others (2002). 

Methods of Data Collection

Prior to any water sampling, USGS and NPS personnel 

reviewed the design and layout of the combined stormwater/

wastewater system in Washington, D.C. to identify areas 

of sewer infrastructure that may discharge directly to Rock 

Creek. A thermal infrared (TIR) survey was conducted to 

identify locations where warm groundwater was entering the 
Methods of Data Collection 7

Figure 3. Generalized location of areas that are served by a 

combined sewer system in Washington, D.C. (modified from 

District of Columbia Water and Sewer Authority, 2002).

creek or its tributaries, and to determine if the source might 

be natural groundwater seeps, leaky water lines, or CSOs. 

Surface-water sampling sites were selected by the USGS and 

NPS on the basis of the results of the TIR survey. Sampling of 

these sites occurred in June 2007, and subsequent passive sampling occurred in 2008 based on the results of the base-flow 

sampling. The following sections describe the methods used to 

locate seeps and the selection of sampling sites.

Thermal Infrared (TIR) Survey and Site Selection

Aerial TIR imagery is an accurate, non-invasive screening tool for the identification of groundwater seeps or pipeline 

discharges over a large area. TIR imagery has been used as a 

remote sensing application to qualitatively and quantitatively 

assess temperature variation in natural systems, including 

groundwater discharge (Banks and others, 1996; Portnoy and 

others, 1998; Majcher and others, 2007).

The USGS worked with the National Park Service Police 

Aviation Group to conduct a high-resolution, low-altitude 

aerial TIR survey of the Washington, D.C. section of the Rock 

Creek Basin and its tributaries within the park boundaries on 

January 31, 2007. Sources of error in TIR imagery in natural 

waters include reflective energy interference and thermal 

stratification (Majcher and others, 2007; Torgersen and others, 

2001). TIR imagery does not differentiate between reflected 

and emitted thermal energy during daylight hours; therefore, 

solar interference can negatively affect the interpretation of 

images (Majcher and others, 2007). To minimize the undesired 

effects of reflection and the effect of solar heating of land or 

water surfaces during daylight, the TIR survey started just 

before dawn, and was completed while the creek and tributaries were still in shadows.

The helicopter and TIR camera are owned and operated 

by the National Park Service Police Aviation Group, 

Washington, D.C. The TIR camera that was used was a FLIR 

model Star Safire 2 mounted under the nose of the helicopter. 

Data were downloaded from the helicopter data system and 

stored on DVDs.

Data from the TIR surveys helped identify specific locations where warm water was discharging to the creek. Many 

of the “warm spots” were the result of water flowing out from 

either storm-sewer outfalls or sections where small streams 

had been piped underground, causing localized warming of 

the discharge water. The identified warm spots were documented and reviewed by USGS and NPS hydrologists, and 23 

sites were selected for sampling on the basis of those results. 

Examples of some of the TIR images are shown in 

Appendix A.

Synoptic Water-Quality Sampling

Surface-water samples were collected and analyzed for 

concentrations of OWCs during base-flow conditions in June 

2007 at 23 sites in the basin (fig. 2). Water samples collected 

from all 23 sites were analyzed for dissolved OWCs and total 

organic carbon (TOC). Water and bed-sediment samples from 

seven of the sites also were analyzed for total OWCs (table 1).

Samples analyzed for dissolved and total OWCs were 

collected by dipping 1-L (liter) baked brown-glass bottles 

into the center of flow where the channel was narrow and the 

stream well mixed. Samples analyzed for TOC were collected 

by dipping a 250-mL (milliliter) brown-glass bottle in the 

center of flow. All samples were shipped overnight to the 

USGS National Water Quality Laboratory (NWQL) in Denver, 

Colorado, on ice with no preservatives. Samples analyzed 

for dissolved constituents were filtered at the NWQL using a 

0.7-micron glass-fiber filter and analyzed at the NWQL using 

polystyrene-divinylbenzene solid-phase extraction and capillary-column gas chromatography/mass spectrometry (GC/MS) 

(Zaugg and others, 2006). Samples analyzed for whole-water 

concentrations were analyzed at the NWQL using continuous 

liquid-liquid extraction and capillary-column GC/MS (Zaugg, 

Smith, and Schraeder, 2006). TOC samples were analyzed at 

the NWQL using high-temperature combustion method 5310B 

(Clesceri and others, 1999).
8 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 1. Station numbers and names, and sample-collection dates for organic wastewater compounds from Rock Creek Park, Washington, D.C., 2007–08. [° ′ ′′ , degrees, minutes, seconds; OWC, organic wastewater compound; X, sample collected; Xd, duplicate samples collected; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey] USGS station number Site name/location Latitude (° ‘ “) Longitude (° ‘ “) June 27–28, 2007 Synoptic sampling for OWCs in: June 27–28, 2008 stormwater sampling July 2–29, 2008 passive sampling Sept. 27–28, 2008 stormwater sampling Water (dissolved) Water (total) Bed sediment 01647994 Rock Creek at MD/DC boundary 385912 770310

X

X

X

01647996 Tributary to Fenwick Branch at Red Bud Lane 385935 770241

X

01647997 Portal Branch at Fenwick Branch 385922 770233

X

X

0164799789 Fenwick Branch above Rock Creek 385903 770232 Xd

X

X

X

0164799790 Storm Sewer to Rock Creek below Fenwick Branch 385901 770230

X

X

01648001 Whittier Run above Rock Creek 385819 770223 Xd

X

X

01648002 Pinehurst Branch above Barnaby Street 385842 770332

X

01648003 Pinehurst Branch tributary near Barnaby Street 385841 770329

X

01648005 Pinehurst Branch at Beach Drive 385817 770238

X

0164800550 Rock Creek tributary near Bingham Drive 385808 770249

X

X

01648010 Rock Creek at Joyce Road 385736 770231

X

X

X

01648011 Luzon Branch at Joyce Road 385739 770231 Xd Xd

X

0164801540 Broad Branch above Soapstone Valley 385644 770305

X

X

0164801550 Soapstone Valley tributary to Broad Branch 385638 770301

X

01648100 Rock Creek above Piney Branch 385607 770252

X

01648200 Piney Branch above Rock Creek 385607 770249 Xd Xd

X

01648300 Rock Creek above Connecticut Avenue 385523 770255

X

01648390 Normanstone Creek above Rock Creek 385508 770322

X

01648450 Dumbarton Oaks tributary above Rock Creek 385456 770334

X

01648500 Rock Creek below Dumbarton Oaks Park 385453 770330

X

01649000 Rock Creek at Q Street 385440 770306 Xd

X

X

01649003 Pipe inflow to Rock Creek, below P Street 385432 770301

X

01649010 Rock Creek above M Street 385405 770330

X

X

X
Methods of Data Collection 9

Sediment Sampling

Creek-bottom sediment samples were collected at seven 

sites and analyzed for concentrations of OWCs in the sediment 

(table 1). Sediment was scooped with clean stainless-steel 

trowels and placed in baked-glass jars. The goal in collecting 

bed samples is to capture primarily fine-grained sediments, on 

which organic compounds tend to adhere. At each of the seven 

sites, most sediment was primarily coarse sand to small gravel, 

with very little fine-grained material available due to the typical high-energy conditions of the stream channels. Samples 

were sent to the NWQL for analysis. 

Stormwater-Quality Sampling

Stormwater samples were collected at the USGS 

gaging station at Rock Creek at Joyce Road (station number 

01648010, fig. 2) using an automated refrigerated sampler 

(American Sigma 900Max) that began sampling when a 

specified stage threshold value was exceeded. Teflon-lined 

tubing was used between the creek and the sampler, and the 

peristaltic-pump tubing in the automated sampler was cleaned 

and sterilized between sampling events to prevent cross-contamination. Sets of three bottles per sample were collected at 

four different times during each storm. One of the three bottles 

was a sterile bottle for analysis of bacteria that was performed 

at the USGS office in Baltimore, Maryland. The other two 

bottles per set were composited and analyzed for either total or 

dissolved OWCs.

Passive Sampling

The potential for high variability in concentrations of 

OWCs in surface water exists if there are intermittent or ongoing releases from leaky sewer lines, CSOs, or shifts in sources 

during storm events. Passive samplers can accumulate the 

contaminants of interest over a period of weeks and are more 

likely to detect evidence of periodic or episodic releases than 

discrete sampling.

The two types of passive samplers used in this study 

were the pharmaceutical type of Polar Organic Chemical 

Integrative Samplers (POCIS) (Alvarez and others, 2004) and 

the Semipermeable Membrane Devices (SPMD) (Huckins 

and others, 2002). The POCIS are designed to sample watersoluble (polar or hydrophilic) organic chemicals from aqueous 

environments. The POCIS consists of a sorbent material 

between two microporous polyethersulfone membranes and 

samples chemicals from the dissolved phase (Alvarez and 

others, 2004, 2009). Sampling of compounds by the POCIS 

is integrative, and analyte concentrations are reported as 

accumulated concentrations over the period of deployment of 

the samplers. After deployment, the samplers were shipped 

to the Environmental Sampling Technologies (EST) lab in 

St. Joseph, Missouri, and the chemicals were extracted into 

methanol, then shipped to the NWQL for analysis. The NWQL 

performed a solvent exchange into methylene chloride prior to 

analysis. 

The SPMD are designed to sample lipid- or fat-soluble 

(nonpolar or hydrophobic) semivolatile organic chemicals 

from water and air. The SPMD consists of a neutral, highmolecular-weight lipid [greater than 600 Daltons (Da)] such 

as triolein, which is encased in a thin-walled [50–100 μm 

(micrometers)] layflat polyethylene membrane tube. The 

nonporous membrane allows the nonpolar chemicals to pass 

through to the lipid where the chemicals are concentrated. 

These devices are designed to mimic the bioconcentration 

processes of living organisms and organic matter, which 

results in elevated contaminant concentrations after exposure 

to trace hydrophobic organic contaminants in aquatic environments (Alvarez and others, 2009). After deployment, the 

samplers were shipped to the EST lab and the chemicals were 

extracted using a dialytic extraction step into methylene chloride. Following dialysis, all sequestered chemicals are in the 

organic solvent (Huckins and others, 2002). 

As both polar and non-polar compounds were detected 

in the June 2007 synoptic sampling, both types of passive 

samplers were required to ensure that all of the compounds 

of interest would be detected by the proper sampling device. 

Both passive samplers were developed by the USGS Columbia 

Environmental Research Center (CERC) in Columbia, 

Missouri, and are marketed for general use solely by EST of 

St. Joseph, Missouri.

POCIS and SPMD samplers were deployed at the five 

sites that had the highest number of detections and sum of 

concentrations during the June 2007 synoptic sampling effort. 

The samplers were deployed on July 2, 2008, and retrieved on 

July 29, 2008, at the following five sites (fig. 2):

U.S. 

Geological 

Survey

station

number

Site name/

location

Number of 

dissolved 

compounds 

detected

Sum of concentrations 

that were 

greater than 

estimated 

concentrations 

(micrograms 

per liter)

01647997 Portal Branch at 

Fenwick Branch

16 2.2

0164799789 Fenwick Branch 

above Rock 

Creek

12 0.9

0164799790 Storm Sewer outfall 

to Rock Creek 

below Fenwick 

Branch

21 0.7

0164800550 Rock Creek 

tributary near 

Bingham Drive

23 4.2

0164801540 Broad Branch above 

Soapstone Valley

15 3.5
10 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

The SPMD and POCIS samplers were constructed 

according to established procedures described in Alvarez 

and others (2007) and Huckins and others (2006). SPMD 

samplers were shipped from EST to the USGS Baltimore 

office in sealed steel cans on ice, and the units were kept on 

ice until deployment. POCIS devices were shipped from EST 

in sealed steel cans, but were not refrigerated. After retrieval, 

the devices were shipped overnight in the sealed steel containers to EST, and the SPMD were shipped on ice. The EST lab 

extracted the chemicals using a dialytic extraction step into 

methylene chloride. Following dialysis, all sequestered chemicals are in the organic solvent (Huckins and others, 2002). 

EST extracted the compounds into ampules and shipped the 

ampules to the NWQL for analysis of OWCs. Extractions 

from POCIS samples from the sites at Rock Creek at Bingham 

Drive and Fenwick Branch above Rock Creek were split at the 

EST lab, and a part of the split sample was sent to the USGS 

Organic Geochemistry Research Group Laboratory (OGRL) in 

Lawrence, Kansas, for analysis for antibiotics.

Estimation of Ambient Concentrations of 

Organic Wastewater Compounds from 

Semipermeable Membrane Devices (SPMD)

Average ambient concentrations of selected chemicals 

can be estimated from SPMD and POCIS integrative sampler 

concentrations using multiple assumptions for chemical 

equilibrium and physical processes. The regression models for 

concentrations from SPMD have been worked out by Alvarez 

and others (2004, 2007, 2009) and their spreadsheet calculator software was used in this study to approximate the average ambient stream concentrations (picograms per liter) from 

the total cumulative sampler concentrations (nanograms per 

SPMD). Alvarez and others (2004) found that the uptake of 

chemicals into the SPMD can be assumed to be linear for up to 

1 month for non-polar compounds (KOW ≥5.0), and given that 

the devices in the current study were deployed for a 4-week 

period, the assumption of linear uptake was used here. POCIS 

samplers target more hydrophilic compounds, so the conversion for ambient concentrations from POCIS samplers was not 

made. Ambient concentrations are assumed not to be depleted 

as the samplers were deployed in flowing water. Alvarez and 

others (2007) developed regression models to estimate the 

sampling rates and SPMD-water partition coefficients (KSW) 

for PCBs, PAHs, and non-polar pesticides, and used these relations in their spreadsheet calculator.

Analytical Methods

A USGS report (Zaugg and others, 2006) describes 

the analytical methods used by the NQWL for the analysis 

of organic wastewater from filtered water. Water samples 

are filtered at the lab and then are extracted by vacuum 

through disposable solid-phase cartridges that contain 

polystyrene-divinylbenzene resin. Cartridges are dried with 

nitrogen gas, and then sorbed compounds are re-eluted with 

dichloromethane-diethyl ether (4:1) and determined by 

capillary-column GC/MS. Recoveries of the target chemicals 

in reagent-water samples fortified at 4 μg/L (micrograms per 

liter) averaged 74 percent ± 7 percent relative standard deviation for all method compounds (Zaugg and others, 2006).

Analytical methods used by the NWQL for the analysis 

of organic wastewater from whole water are described in 

Zaugg, Smith, and Schroeder (2006). Wastewater compounds 

in whole-water samples are extracted using continuous 

liquid-liquid extractors and methylene chloride solvent, and 

then determined by capillary-column GC/MS. Recoveries 

in reagent-water samples fortified at 0.5 μg/L averaged 72 

percent ± 8 percent relative standard deviation. The concentrations of 21 compounds were always reported as estimated 

because method recovery was less than 60 percent 

(Zaugg, Smith, and Schroeder, 2006). 

Stormwater samples and two POCIS samples were analyzed for concentrations of antibiotics and some pharmaceuticals by the USGS OGRL. The analytical method was modified 

from a liquid chromatography/tandem mass spectrometry 

(LC/MS/MS) version of the on-line solid-phase extraction 

(OLSPE) LC/MS method in Meyer and others (2007). 

Individual antibiotic compounds were analyzed using multiple 

reaction monitoring (MRM). The method reporting levels 

(MRLs) ranged from 0.005 to 0.01 μg/L for all analytes except 

ibuprofen and sulfadiazine, which were 0.1 μg/L. POCIS and 

SPMD extracts were analyzed at the NWQL by GC/MS.

Quality Assurance of Data

One field blank was collected and analyzed during the 

synoptic sampling of June 2007 for dissolved and total OWCs 

to measure potential background contamination due to samplecollection methods. The field blank result included a detection 

of one dissolved compound, DEET, at an estimated concentration of 0.006 μg/L. The lowest estimated detection of DEET in 

any environmental sample was roughly 4 times the concentrations found in the blank, indicating only a minor interference 

caused by either the analysis or the sampling process. There 

were no other detections or estimated concentrations for any 

other analyte in the total OWC field blank.

Duplicate samples for dissolved OWCs were collected 

at 5 of the 23 sites during the synoptic sampling in June 2007 

to determine reproducibility of results. In the duplicate OWC 

samples, only one compound (Fyrol CEF) from one duplicate 

pair was detected above the MRL, and that compound was 

detected in both samples, at concentrations of 0.9 and 1.0 

μg/L (table 2), indicating good reproducibility. There were 37 

duplicate pairs that had estimated concentrations below MRLs 

in both samples for a given compound. There were 11 pairs 

that had an estimated concentration given for one sample, 

where the associated sample was listed as a “less than” value; 

however, all of these results were in agreement (“less than 
Methods of Data Collection 11

0.5” compared to an estimated concentration of 0.1 μg/L). One 

duplicate pair was collected for TOC, and the results were 2.1 

and 2.4 μg/L, also indicating good reproducibility.

At the five sites, there were 49 pairs of OWCs where 

there was a detection of a given compound in either one or 

both of the associated duplicates. Of those 49 detections, all 

of the comparable results were in agreement either by being 

within 0.1 μg/L of each other when a detection occurred in 

both samples, or by the detected concentration being within 

the range of the detection limit of the associated sample (an 

estimated concentration of 0.05 μg/L compared to a “less 

than” 0.2 μg/L). 

Duplicate samples for total OWCs were collected at two 

of the seven sites during the synoptic sampling in June 2007 

for OWCs. In the first duplicate pair, nine compounds had 

estimated detections for both samples, and two compounds 

had an estimated value for one sample, but not the other. In the 

second pair, six compounds had estimated detections in both 

samples, and three had an estimated value for one sample, but 

not the other. In both duplicate sets, where there were estimated values for one sample and not the other, all pairs except 

for one were in agreement (<1.6 compared to an estimated 

value of 0.4 μg/L for 5-methyl-1H-benzotriazole). The exception had an estimated concentration of 1.2 μg/L compared to 

a “less than” 0.8 μg/L. Because no compound had detections 

above the MRL in either of the duplicate samples for wholewater samples, no comparison could be made to determine 

relative percent differences. 

Stormwater samples were collected from the Rock Creek 

at Joyce Road sampling station using a refrigerated automatic sampler, and analyzed for TOC, suspended sediment, 

and OWCs during storms in June and September 2008. An 

equipment blank was collected from the Joyce Road automatic sampler prior to the June 2008 stormwater sampling to 

determine if any crossover contamination for TOC or OWCs 

was caused by the sample lines between the creek and the 

sampler. A field blank and a field duplicate were collected 

during the September 2008 sampling. The only detection in 

the equipment blank was for TOC at a concentration of 0.25 

mg/L (milligrams per liter), at roughly one-sixth of the lowest concentration in any of the environmental samples. Two 

OWCs were detected in the field blank: DEET (at 0.02 μg/L), 

and tris(2-butoxyethyl)phosphate was detected at an estimated 

concentration of 0.24 μg/L. The low concentration of DEET 

found in the blank was not enough to qualify the field concentrations; however, the concentration of tris(2-butoxyethyl)

phosphate detected in the blank at a concentration of at least 

half the concentrations in the field samples brings detected 

concentrations for that compound into question. (Those concentrations are qualified in data tables later in the report with a 

“v” indicating blank contamination.)

There were two sets of storm samples collected with 

the automatic sampler at Joyce Road—on June 27–28 and 

September 6, 2008. During the September 6 sampling, one 

pair of duplicate samples was analyzed for dissolved OWCs, 

and one pair of duplicate samples was analyzed for both 

dissolved and total OWCs. For the duplicate samples, there 

were 58 data pairs where there was a value for both samples. 

Of those 58 data pairs, 38 had the same “less than” values for 

both analyses. There were 14 pairs where there were detections in both samples. Of those 14 pairs, 11 had both concentrations as estimated values (below the MRL), but each 

concentration was within 0.03 μg/L of the concentration in 

the respective duplicate. Three of the 14 pairs had concentrations above the MRL in both samples, and each concentration 

was within 0.02 μg/L of the concentration in the respective 

duplicate. There were five duplicate pairs where there was 

an estimated detection in one sample, but not in the other; 

however, in each of the five pairs, all were in agreement (for 

example, an estimated concentration of 0.53 μg/L compared to 

a “less than” 1.0 μg/L). 

The SPMD samples included two blanks, a field blank, 

and a “day zero” blank that was prepared at the EST lab, kept 

in a freezer, and sent to the NWQL for analysis along with the 

environmental samples. The SPMD field blank was opened 

at each of the five sites for the same amount of time that each 

deployed SPMD was open to the air, during both deployment 

and retrieval of the devices. This procedure is required because 

the SPMD devices are much more susceptible to absorbing 

compounds from the air than the POCIS devices. Because the 

field blank was subjected to 5 times the exposure as any of 

the deployed devices (same amount of time at five sites), the 

concentration in the environmental samples was compared to 

one-fifth of the concentration in the field blank to estimate the 

amount of atmospheric absorbance from each sampler. Field 

concentrations that are less than 10 times the concentrations in 

the blanks are qualified with a “v” before the concentrations 

shown in tables and appendixes indicating potential interference. Compounds that were frequently detected in SPMD 

blanks were diethylphthalate, 1-methylnapthalene, 2-6 dimethylnaphthalene, 2-methylnaphthalene, diethylhexylphthalate, 

and naphthalene. These compounds also were found in SPMD 

samples from this study.

An extraction blank was generated during the processing 

of the POCIS, consisting of the same sorbent material that was 

used for the field-deployed units. The extraction blank was 

sealed in a glass ampule, kept in a freezer, and sent to the lab 

along with the environmental samples. The extraction blank 

was analyzed using the same method that was used for the 

field units. Any detection in the extraction blank during the 

construction or analysis of the material would cause the environmental samples to be qualified as having blank contamination. Eight compounds were detected in the extraction blank. 

Environmental samples in which these eight compounds were 

detected, and in which there were substantial concentrations 

in the extraction blank, are qualified in data tables as having 

blank contamination.

Surrogate compounds are injected into a sample at the 

laboratory to determine how much of a known concentration 

in a sample is detected by the instrument. The concentration 

is reported as the percent recovered of the original injected 

compounds. Acceptable percent recoveries for reporting 
12 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 2. Concentrations of total organic carbon, and dissolved organic wastewater compounds detected in water from Rock Creek Park, Washington, D.C., June 27–28, 2007. —Continued [μS/cm, microsiemens per centimeter;  ̊C, degrees Celsius; mg/L, milligrams per liter; --, data not available; dup, duplicate sample; duplicate pairs are in shaded cells for comparison; <, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; Note: list of compounds not detected is shown in Appendix B] USGS station number Station name Date Time pH, (stan- dard units) Specific conduc- tance (μS/cm) Temper- ature, water ( ̊C) Total organic carbon (mg/L) Dissolved constituents (micrograms per liter) Anthra- quinone Benzo- phenone Bro- macil Caf- feine Camphor 01647994 Rock Creek at MD/DC boundary 6/27/2007 0645 7.5 486 23.5 3.7 <.16 <.18 <.4 E.05 <.1 01647996 Trib to Fenwick Branch at Red Bud Lane 6/27/2007 0715 7.4 420 20.4 1.4 <.16 <.18 <.4 <.2 <.1 01647997 Portal Branch at Fenwick Branch 6/27/2007 0745 7.5 1,100 21.6 2.8 E.01 E.03 <.4 E.03 E.04 0164799789 Fenwick Branch above Rock Creek 6/27/2007 0815 7.6 869 21.6 2.7 E.01 E.02 <.4 E.03 E.04 0164799789 Fenwick Branch above Rock Creek (dup.) 6/27/2007 0816 7.6 869 21.6 -- <.16 E.03 <.4 E.03 E.04 0164799790 Storm Sewer to Rock Creek below Fenwick Br. 6/27/2007 0830 7.3 821 18.3 1.9 E.02 E.1 E.3 E.1 <.1 01648001 Whittier Run above Rock Creek 6/27/2007 0845 7.3 821 18.3 5.6 <.16 <.18 <.4 <.2 E.02 01648001 Whittier Run above Rock Creek (dup.) 6/27/2007 0846 7.3 821 18.3 -- <.16 E.02 <.4 <.2 E.02 01648002 Pinehurst Branch above Barnaby St. 6/28/2007 0645 7.1 590 20.9 2.5 <.16 <.18 <.4 <.2 <.1 01648003 Pinehurst Branch trib near Barnaby St. 6/28/2007 0700 7.3 626 20.2 4.6 <.16 <.18 <.4 E.1 <.1 01648005 Pinehurst Branch at Beach Drive 6/28/2007 0730 7.5 459 21.3 2.4 <.16 <.18 <.4 <.2 <.1 0164800550 Rock Creek trib. near Bingham Drive 6/28/2007 0800 7.4 651 20.6 2.2 E.02 E.13 <.4 3 E.1 01648010 Rock Creek at Joyce Road 6/27/2007 0930 7.7 484 24.3 3.7 E.01 <.18 <.4 E.1 E.03 01648011 Luzon Branch at Joyce Road 6/27/2007 0945 7.6 982 21.6 1.7 E.01 <.18 <.4 E.1 <.1 01648011 Luzon Branch at Joyce Road (dup.) 6/27/2007 0946 7.6 982 21.6 -- E.02 <.18 <.4 E.1 <.1 0164801540 Broad Branch above Soapstone Valley 6/28/2007 0815 7.7 729 21.8 3.2 <.16 E.04 <.4 2.3 E.1 0164801550 Soapstone Valley trib. to Broad Branch 6/28/2007 0830 8.0 825 21.8 2.6 <.16 <.18 <.4 E.02 <.1 01648100 Rock Creek above Piney Branch 6/27/2007 1030 8.2 498 25 3.9 <.16 <.18 <.4 E.04 E.03 01648200 Piney Branch above Rock Creek 6/28/2007 900 8.1 679 24 2.4 <.16 <.18 <.4 E.05 <.1 01648200 Piney Branch above Rock Creek (dup.) 6/28/2007 901 8.1 679 24 2.1 <.16 <.18 <.4 <.2 <.1 01648300 Rock Creek above Connecticut Avenue 6/27/2007 1100 8.4 502 25.5 3.5 E.01 <.18 <.4 E.04 E.02 01648390 Normanstone Creek above Rock Creek 6/27/2007 1315 7.6 664 21.8 1.4 <.16 <.18 <.4 E.05 <.1 01648450 Dumbarton Oaks trib above Rock Creek 6/27/2007 1115 8.0 609 21.4 1.8 <.16 <.18 <.4 <.2 <.1 01648500 Rock Creek below Dumbarton Oaks Park 6/27/2007 1130 8.3 508 25.8 3.8 <.16 <.18 <.4 E.04 E.02 01649000 Rock Creek at Q St. 6/27/2007 1145 8.3 509 26.4 3.9 <.16 <.18 <.4 E.04 E.02

01649000 Rock Creek at Q St. (dup.) 6/27/2007 1146 8.3 509 26.4 -- <.16 <.18 <.4 E.04 E.0201649003 Pipe inflow to Rock Cr. below P St. 6/27/2007 1200 8.0 469 25.9 2.1 E.04 <.18 <.4 E.04 <.101649010 Rock Creek above M St. 6/27/2007 1230 8.3 510 26.2 3.6 <.16 <.18 <.4 E.05 E.0301648010 Field blank 6/27/2007 0929 -- -- -- -- <.16 <.18 <.4 <.2 <.1
Methods of Data Collection 13

Table 2. Concentrations of total organic carbon, and dissolved organic wastewater compounds detected in water from Rock Creek Park, Washington, D.C., June 27–28, 2007.—Continued[μS/cm, microsiemens per centimeter;  ̊C, degrees Celsius; mg/L, milligrams per liter; --, data not available; dup, duplicate sample; duplicate pairs are in shaded cells for comparison; <, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; Note: list of compounds not detected is shown in Appendix B]

USGS

station 

number

Dissolved constituents (micrograms per liter)

Carbazol Choles- terol 3-beta- Copro- stanol Coti- nine p- Cresol N,N-Diethyl- meta-tolua- mide [DEET] Dieth- oxynonyl- phenol Dieth- oxyoctyl- phenol Fluoran- thene HHCB Indole Iso- phor- one d-Limo- nene Metola- chlor Men- thol 5-Methyl- 1H-benzo- triazole

01647994 <.08 <1 <1.6 <.4 <.18 E.1 <5 <1 <.08 <.5 <.14 <.1 <.1 E.01 <.2 E.201647996 <.08 <1 <1.6 <.4 <.18 E.02 <5 <1 <.08 E.01 <.14 <.1 <.1 <.16 <.2 <1.801647997 <.08 <1 <1.6 <.4 E.1 0.2 <5 <1 E.02 <.5 <.14 <.1 <.1 E.01 <.2 E.120164799789 <.08 <1 <1.6 <.4 <.18 E.1 <5 <1 E.01 E.02 <.14 <.1 <.1 E.01 <.2 <1.80164799789 <.08 E.3 <1.6 <.4 <.18 E.1 <5 <1 E.01 E.02 <.14 E.01 <.1 E.01 <.2 <1.80164799790 E.01 <1 <1.6 E.04 <.18 0.5 <5 <1 E.01 E.02 <.14 0.2 <.1 <.16 E.2 E.301648001 <.08 <1 <1.6 <.4 E.02 <.2 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 <1.801648001 <.08 <1 <1.6 <.4 <.18 <.2 <5 <1 <.08 <.5 <.14 <.1 <.1 E.01 <.2 <1.801648002 <.08 <1 <1.6 <.4 <.18 E.04 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 <1.801648003 <.08 <1 <1.6 <.4 <.18 E.02 <5 <1 <.08 <.5 E.02 <.1 <.1 <.16 <.2 <1.801648005 <.08 <1 <1.6 <.4 <.18 <.2 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 <1.80164800550 <.08 E1 E.6 E.07 <.18 1.1 E.2 <1 E.02 E.2 E.2 E.03 <.1 <.16 E.2 <1.801648010 <.08 E.4 E.1 <.4 <.18 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 E.01 <.2 E.101648011 <.08 <1 <1.6 <.4 <.18 E.1 <5 E.1 <.08 E.1 <.14 <.1 <.1 E.01 <.2 E.301648011 <.08 <1 <1.6 <.4 <.18 E.1 <5 E.1 <.08 E.1 <.14 <.1 <.1 E.01 <.2 E.20164801540 <.08 E.6 E.02 <.4 E.1 0.3 <5 <1 <.08 E.2 <.14 <.1 E.1 <.16 0.9 <1.80164801550 <.08 <1 <1.6 <.4 E.04 E.1 <5 <1 <.08 E.03 <.14 <.1 <.1 E.01 <.2 E.301648100 <.08 E.3 <1.6 <.4 <1.8 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 <.16 <.2 <1.801648200 <.08 <1 <1.6 <.4 <.18 E.02 <5 <1 <.08 E.02 <.14 <.1 <.1 <.16 <.2 <1.801648200 <.08 <1 <1.6 <.4 <.18 E.03 <5 <1 <.08 E.02 <.14 <.1 <.1 <.16 <.2 <1.801648300 <.08 <1 <1.6 <.4 <1.8 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 E.01 <.2 E.201648390 <.08 <1 <1.6 <.4 <1.8 E.03 <5 <1 <.08 E.02 <.14 <.1 <.1 <.16 <.2 <1.801648450 <.08 <1 <.16 <.4 <1.8 E.03 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 <1.801648500 <.08 <1 <.16 <.4 <1.8 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 E.01 <.2 E.101649000 <.08 <1 <1.6 <.4 <.18 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 <.16 <.2 E.201649000 <.08 <1 <1.6 <.4 <.18 E.1 <5 <1 E.01 <.5 <.14 <.1 <.1 <.16 <.2 E.201649003 <.08 <1 <1.6 <.4 <1.8 E.04 <5 <1 <.08 <.5 <.14 <.1 <.1 E.02 <.2 <1.801649010 <.08 E.5 E.2 <.4 <1.8 E.1 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 E.2Field blank <.08 <1 <1.6 <.4 <1.8 E0.006 <5 <1 <.08 <.5 <.14 <.1 <.1 <.16 <.2 <1.8
14 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 2. Concentrations of total organic carbon, and dissolved organic wastewater compounds detected in water from Rock Creek Park, Washington, D.C., June 27–28, 2007. —Continued [μS/cm, microsiemens per centimeter;  ̊C, degrees Celsius; mg/L, milligrams per liter; --, data not available; dup, duplicate sample; duplicate pairs are in shaded cells for comparison; <, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; Note: list of compounds not detected is shown in Appendix B] USGS station number Dissolved constituents (micrograms per liter) 3-Methyl- 1H- indone [Skatol] Methyl Salicy- late Monoe- thoxy- octyl- phenol Phenan- threne Pyrene beta- Sitos- terol Tetra- chloro- ethylene Tri- bromo- methane Triclo- san Organophosphate flame retardants Tri- ethyl citrate Tri- phenol phos- phate Tributyl phos- phate Tris(2-bu- toxyethyl) phosphate Tris(2-chloro- ethyl)phosphate [FYROL CEF] Tris(dichloroiso- propyl)phosphate [FYROL PCF] 01647994 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 E.1 E0.1 <.2 <.4 <.16 01647996 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 E5.6 E.04 <.2 <.4 <.16 01647997 <.08 <.18 <1 <.1 E.02 <2 <.2 <.1 <.2 E.003 E.1 2 E.1 E.03 E.01 0164799789 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 E.1 0.9 E.04 <.4 <.16 0164799789 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 E.1 1 E.04 E.01 <.16 0164799790 <.08 <.18 E.04 <.1 E.01 <2 E.1 <.1 <.2 <.2 E.1 E.1 E.02 E.1 E.02 01648001 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 01648001 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 01648002 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 01648003 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 E.1 <.4 <.16 01648005 E.01 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 0164800550 0.1 <.18 E.08 E.02 E.01 E.9 <.2 <.1 <.2 E.02 E.2 E.06 E.04 <.4 E.02 01648010 <.08 <.18 <1 <.1 E.01 E.1 <.2 <.1 <.2 <.2 <.5 E.04 E.02 <.4 <.16 01648011 <.08 <.18 E.04 <.1 E.01 <2 <.2 <.1 E.02 <.2 E.2 E.04 E.04 E.02 <.16 01648011 <.08 <.18 E.03 <.1 E.01 <2 <.2 <.1 E.02 <.2 E.3 E.04 E.04 E.01 <.16 0164801540 E.1 E.01 <1 <.1 <.08 <2 <.2 <.1 E.1 <.2 E1.4 <.2 <.2 E.04 <.16 0164801550 <.08 <.18 <1 <.1 <.08 <2 E.1 <.1 <.2 E.003 <.5 E.1 E.1 <.4 <.16 01648100 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 E.2 E.05 <.2 <.4 <.16 01648200 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 E.1 E.04 E.04 <.4 <.16 01648200 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 E.05 <.2 <.4 <.16 01648300 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 E.1 E.04 E.03 <.4 <.16 01648390 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 01648450 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 <.5 <.2 <.2 <.4 <.16 01648500 <.08 E.005 <1 <.1 E.01 <2 E.01 <.1 <.2 <.2 E.1 E.04 E.04 <.4 <.16

01649000 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 <.5 E.04 E.03 <.4 <.1601649000 <.08 <.18 <1 <.1 E.01 <2 <.2 <.1 <.2 <.2 E.1 E.03 E.03 <.4 <.1601649003 <.08 <.18 <1 E.1 <.08 <2 E1.1 E4.5 <.2 <.2 <.5 <.2 <.2 <.4 <.1601649010 <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.2 <.2 E.1 E.05 <.2 <.4 <.16Field blank <.08 <.18 <1 <.1 <.08 <2 <.2 <.1 <.4 <.2 <.5 <.2 <.2 <.4 <.18
Water-Quality Data 15

quantified values typically range from about 50 to 125 percent 

depending on the surrogate, but bisphenol A-d3 had the lowest 

acceptable recovery at 5 percent. When percent recoveries are 

out of acceptable ranges, concentrations of compounds that are 

associated with the specific surrogate compounds are flagged 

as “R-deleted” in data tables. During this investigation, there 

were unacceptable ranges of analytical recoveries for dissolved bisphenol A. Therefore, results for bisphenol A and 

pentachloroethane were deleted from the data tables.

Water-Quality Data

Results from the analysis of the June 2007 synoptic 

water-quality and streambed sediment sampling, the stormwater-quality sampling from Rock Creek at Joyce Road, and the 

passive samplers are presented in the following sections. Data 

are presented in tables within each section, and in appendixes 

at the end of the report. A graph showing the long-term average discharge from 1929–2008 and daily mean discharge for 

water years 2007–08 from the gage on Rock Creek at Sherrill 

Drive is shown in figure 4. The time periods for each of the 

sampling events described in the following sections are also 

included in figure 4 to show streamflow conditions during 

each sampling event.

Synoptic Water-Quality Data

Surface-water samples were collected at the 23 sites 

(fig. 2) on June 27–28, 2007 during base-flow conditions, and 

analyzed for dissolved OWCs, dissolved pharmaceuticals, 

and TOC. Seven of the sites were on the main channel of 

Rock Creek, and 16 sites were on tributaries. Additional water 

samples were collected at seven sites and analyzed for total 

concentrations of OWCs. Bottom sediment samples were 

collected at the same seven sites as those sampled for total 

concentrations, and analyzed for concentrations of OWCs in 

the sediment (table 1). Samples were sent to the NWQL for 

analysis. 

Dissolved Organic Wastewater Compounds

Water samples were filtered and analyzed at the lab 

for concentrations of 66 different dissolved OWCs. Thirty 

compounds were detected at least at one site; concentrations 

of those 30 compounds are listed in table 2. A list of all 66 

compounds that were analyzed, and which compounds were 

detected or not detected, is presented in Appendix B. Six dissolved OWCs had concentrations above the MRL and those 

results are summarized in table 3. There were no detections or 

estimated concentrations in the field blank. 

The MRL is defined by the NWQL as the smallest 

measured concentration of a substance that can be reliably 

quantified by use of a given analytical method. It is the “less 

than” value reported when an analyte is not detected. The “E” 

remark code is used to signify that a measured concentration 

is estimated by the NWQL. A wide variety of conditions can 

justify invoking the “E” remark (Childress and others, 1999). 

In this report, data values qualified with the “E” remark are 

typically below the MRL, but above the long-term method 

detection limit (LT-MDL), and are coded as estimated because 

of lower precision in these values. All MRLs ranged from 0.08 

to 1.4 μg/L, with the exception of one compound (diethoxynonylphenol) that had a MRL of 5 μg/L (table 2). 

The three compounds detected at more than half the sites 

were caffeine, DEET, and Fyrol CEF. Caffeine is a natural 

stimulant and diuretic used throughout the world. DEET is 

a common insect repellant. Fyrol CEF [tris(2-chloroethyl)

phosphate] is used as a flame retardant in plastics, and in the 

construction of both flexible and rigid foams.

The number of detections found at each site ranged from 

0 to 24 compounds (table 2) out of 66 compounds that were 

analyzed (Appendix B). The five sites (fig. 2) with the greatest 

number of detections along with the number of detections at 

each site were: 

U.S. 

Geological 

Survey 

station 

number

Site name/

location

Number of 

detections of 

organic wastewater 

compounds

0164800550 Rock Creek tributary near 

Bingham Drive

24

0164799790 Storm sewer to Rock Creek 

below Fenwick Branch

21

01647997 Portal Branch at Fenwick 

Branch

16

0164801540 Broad Branch above 

Soapstone Valley

15

0164799789 Fenwick Branch above 

Rock Creek

14

These five sites were selected for the placement of passive POCIS and SPMD samplers to allow time-weighted measurements in July 2008, a month that included several storms. 

Of the sites on the main stem of Rock Creek within Rock 

Creek Park, the number of detections of dissolved OWCs in 

the synoptic survey was highest at the Joyce Road site 

(13 detections), where the USGS operates a gaging station that 

includes a refrigerated automatic stream sampler. Downstream 

from Joyce Road, stations on the main stem Rock Creek had 

from 8 to 12 detections of OWCs. 
16 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Figure 4. Long-term average discharge and daily mean discharge from October 2006 through September 2008 at Rock 

Creek at Sherrill Drive, Rock Creek Park, Washington, D.C.

Table 3. Summary of dissolved organic wastewater compounds detected at concentrations above method reporting levels in 

samples from Rock Creek Park, June 27–28, 2007.

[μg/L, micrograms per liter; see table 2 for details and results by site]

Compound name Common 

compound uses

Maximum 

concentration 

(μg/L)

Number of sites 

with detections 

above the method 

reporting level

Number of sites 

with detections 

below the method 

reporting level 

Method 

reporting level 

(μg/L)

Caffeine Stimulant 3 2 16 0.2

N,N-Diethyl-meta-toluamide 

[DEET]

Insect repellant 1.1 3 17 0.2

Tris(2-chloroethyl)phosphate 

[FYROL CEF]

Manufacturing additive/

fire retardant

2 2 13 0.2

Isophorone Solvent 0.2 1 2 0.1

Menthol Fragrance 0.9 1 2 0.2

3-Methyl-1H-indone [Skatol] Fragrance 0.1 1 2 0.08

Dissolved Pharmaceuticals

Water samples were collected from each of the 23 sites 

(fig. 2) for analysis of a suite of nine common pharmaceuticals 

at the USGS NWQL (table 4). Of those nine compounds, the 

compounds butalbital and oxycodone were the only compounds detected at estimated concentrations (0.2 μg/L) that 

were below the MRL of 0.4 μg/L. Butalbital is a barbiturate 

that is often combined with aspirin and acetaminophen by 

manufacturers to form other medications. Oxycodone is an 

active ingredient in widely prescribed pain medications. Each 

of these medications was detected only at the Rock Creek 

tributary near Bingham Drive (station 0164800550), the 

sampling station with the greatest number of detections of 

dissolved OWCs, which is not in a region that is served by a 

CSS system (fig 3). POCIS and SPMD samplers were placed 

at this site in July 2008 on the basis of results from dissolved 

pharmaceuticals and OWCs; these results are described in the 

Passive-Sampler Data section of this report.
Water-Quality Data 17

Table 4. Concentrations of dissolved pharmaceuticals in water samples from Rock Creek Park, Washington, D.C., June 27–28, 2007.[<, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; concentrations above method reporting levels are shown in bold; --, data not available; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey]

USGS

station

number

Station name Date

Dissolved concentrations 

(micrograms per liter)

Codeine Butalbital Chlorpheni- ramine Diazepam Phendimet- razine Metaxa- lone Metha- done Oxyco- done Hydro- codone

1647994 Rock Creek at MD/DC boundary 6/27/2007 <.4 -- <.04 <.04 <.4 <4 <.4 <.4 <.41647996 Tributary to Fenwick Branch at Red 

Bud Lane

6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1647997 Portal Branch at Fenwick Branch 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4164799789 Fenwick Branch above Rock Creek 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4164799790 Storm sewer to Rock Creek below 

Fenwick Branch

6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1648001 Whittier Run above Rock Creek 6/27/2007 <.4 -- <.04 <.04 <.4 <4 <.4 <.4 <.41648002 Pinehurst Branch above Barnaby Street 6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648003 Pinehurst Branch tributary near 

Barnaby Street

6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1648005 Pinehurst Branch at Beach Drive 6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4164800550 Rock Creek tributary near Binghan 

Drive

6/28/2007 <.4 E.2 <.04 <.04 <.4 <4 <.4 E.2 <.4

1648010 Rock Creek at Joyce Road 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648011 Luzon Branch at Joyce Road 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4164801540 Broad Branch above Soapstone Valley 6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4164801550 Soapstone Valley tributary to Broad 

Branch

6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1648100 Rock Creek above Piney Branch 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648200 Piney Branch above Rock Creek 6/28/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648300 Rock Creek above Connecticut Avenue 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648390 Normanstone Creek above Rock Creek 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41648450 Dumbarton Oaks tributary above Rock 

Creek

6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1648500 Rock Creek below Dumbarton Oaks 

Park

6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1649000 Rock Creek at Q Street 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.41649003 Pipe inflow to Rock Creek below P 

Street

6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4

1649010 Rock Creek above M Street 6/27/2007 <.4 <.4 <.04 <.04 <.4 <4 <.4 <.4 <.4
18 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Total Organic Wastewater Compounds

Whole-water samples to be analyzed for total concentrations of organic wastewater compounds were collected at 7 of 

the 23 sites that were sampled for dissolved OWCs. Three of 

the seven sites were on the main stem of Rock Creek, and the 

other four were on tributaries. Duplicate samples from two of 

the seven sites were collected and analyzed. One field blank 

was collected for analysis for total OWCs. Analyses of wholewater samples are more likely to detect OWCs that are carried 

on fine-grained and colloidal material than analyses of filteredwater samples, but are limited by generally higher reporting 

levels than for dissolved concentrations. 

Analyses were performed for the presence of 69 compounds, and 20 of these compounds were detected at one or 

more sites. A summary of the number of detections by analyte 

is shown in table 5. All results for the 20 detected compounds 

by station are shown in table 6. A list of all compounds that 

were analyzed for, including compounds that were not 

detected, is shown in Appendix C. 

 Of the 20 detected compounds, the concentration of only 

one was above the MRL (diethylphthalate, 0.6 μg/L, at the 

upstream site at the MD/DC boundary). Diethylphthalate is a 

plasticizer and industrial solvent and is used in many applications including cosmetics and personal-care products, food 

packaging, and other plastics. Results for the other 19 OWCs 

were all estimated values near or below the MRL and are qualified. MRLs ranged from 0.2 to 3.2 μg/L, with 43 of the 69 

compounds having a MRL of 0.2 μg/L. Compounds detected 

in these samples were from a wide range of sources including 

plasticizers, herbicides, flame retardants, wood preservatives, 

disinfectants, anti-corrosives, fragrances, and fecal indicators. 

Fifteen of the 20 compounds detected in the wholewater analyses also were detected in the unfiltered samples. 

Concentrations of DEET, organophosphate flame retardants, 

and HHCB, a common fragrance in cosmetics and detergents, 

were similar between the dissolved and whole-water analyses, 

indicating that these were primarily in the dissolved phase. 

Five compounds were detected in the whole-water samples but 

not detected in the filtered samples. These compounds were 

atrazine and 1,4-dichlorobenzene (pesticides), 3,4-dichlorophenyl isocyanate and diethylphthalate (plasticizers), and 

pentachlorophenol (wood preservative). On the main stem of 

Rock Creek, the number of detections of wastewater compounds in whole-water samples actually decreased slightly 

with distance downstream from the upstream site at the MD/

DC boundary.

Synoptic Bed-Sediment Data

Samples of creek-bottom sediments were collected at 

seven sites in the study area on June 27–28, 2007 (fig. 2), 

and analyzed for concentrations of OWCs. Some organic 

compounds are less soluble than others, and may reside in 

the particulate phase in aquatic environments; therefore, bed 

sediments (particularly fine-grained sediments) may act as 

reservoirs for these compounds. Creek-bottom samples were 

collected with the intention of gathering primarily fine-grained 

sediments; however, because of the relatively high-energy 

hydrologic environment at the seven stations, there was very 

little fine-grained material available for collection. Samples 

were collected from small pools within about 50 yards 

upstream or downstream from the water-quality sampling sites 

in order to collect enough fine-grained bed sediment suitable 

for analysis.

Bed sediments were analyzed for 56 OWCs 

(Appendix D), of which 22 compounds were detected at at 

least one site (table 7). The following OWCs were detected in 

the sediment at each of the seven sites:

Compound Category Uses

Anthracene PAH1 dyes, insecticides, wood preservative

Anthraquinone PAH dyes, bird repellant

Benzo[a]pyrene PAH formed from incomplete combustion 

of organic materials

Carbazole OWC2 insecticide, dyes, lubricants

Fluoranthene PAH asphalt and coal tar

Indole OWC used in perfumes and fragrances, 

and found in coal tar

Phenanthrene PAH component of tar, diesel fuel, dyes, 

drugs, explosives

Pyrene PAH asphalt and coal tar

1

 Polycyclic aromatic hydrocarbon.

2

 Organic wastewater compound.

Fluoranthene, phenanthrene, and pyrene were three of 

the four compounds detected at the highest overall concentrations in bed sediment at each of the seven sites. This suite 

of compounds was found at all seven sites, and all are PAHs 

that are commonly found in asphalts, indicating that asphalt 

may be a likely source given the urban nature of much of the 

Rock Creek Basin (Van Metre and Mahler, 2005). The fourth 

compound was benzo[a]pyrene, a PAH that is a combustion 

byproduct commonly found in urban environments (Van Metre 

and Mahler, 2005). Two other PAH compounds that were 

found in sediment at each site, but at generally lower concentrations, were anthracene and carbazole, each of which has a 

range of sources. 

Selected PAHs in bed sediment were sampled by Miller 

and others (2006) at Peirce Mill and by Anderson and others 

(2002) at three stations in the Park, one of which was very 

close (within 100 yards) to one of the seven stations sampled 

during this study (Rock Creek at Q Street). Four PAH compounds found in the study byAnderson and others (2002) 

that also were analyzed in this investigation were anthracene, 

benzo[a]pyrene, fluoranthene, and pyrene. A comparison of 

concentrations for those four compounds at Rock Creek at 
Water-Quality Data 19

Table 5. Summary of total organic wastewater compounds detected in water samples from Rock Creek Park, during base-flow synoptic June 27–28, 2007.[μg/L, micrograms per liter; total number of sites sampled is 23; see table 6 for details and results by site; --, not applicable or no detections for that category; duplicate analyses are not double counted; E, estimated result—compound was detected but value was less than the reporting level with lower precision]

Compound name Typical use of compound

Number of 

sites with 

detections, but 

below method 

reporting level

Number of sites 

with detections at 

greater than the 

method reporting 

level

Maximum 

concentration 

(μg/L)

Method 

reporting 

level 

(μg/L)

Detected in:

Main channel Tributary

Diethylphthalate Plasticizer -- 1 0.6 0.2 x --Atrazine Herbicide 6 -- E0.10 0.2 x xN,N-Diethyl-meta-toluamide [DEET] Insect repellant 6 -- E0.16 0.2 x xTris(2-chloroethyl)phosphate Flame retardant 5 -- E0.51 0.2 x xTris(dichloroisopropyl)phosphate Flame retardant 5 -- E0.05 0.2 x xTris(2-butoxyethyl)phosphate Flame retardant 4 -- E0.43 0.2 x xCholesterol Sterol 4 -- E0.78 0.8 x x1,4-Dichlorobenzene Moth repellant 4 -- E0.07 0.2 x xMetolachlor Herbicide 4 -- E0.04 0.2 x x3-beta-Coprostanol Fecal indicator 3 -- E0.59 0.8 x xCaffeine Stimulant 2 -- E0.10 0.2 x xCamphor Flavor 2 -- E0.04 0.2 x x5-Methyl-1H-benzotriazole Anti-corrosive 2 -- E0.40 1.6 x xPentachlorophenol Wood preservative 2 -- E1.16 0.8 x xTetrachloroethylene Solvent 2 -- E0.13 0.4 x xDiethoxyoctylphenol [OP2EO] Detergent 1 -- E0.38 0.32 -- xTriclosan Antimicrobial 1 -- E0.04 0.2 -- xHexahydrohexamethylcyclopentabenzopyran 

[HHCB]

Fragrance 1 -- E0.09 0.2 -- x

Bromacil Herbicide 1 -- E0.05 0.2 -- x3,4-Dichlorophenylisocyanate Herbicide 1 -- E1.40 -- x --
20 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 6. Concentrations of total organic wastewater compounds detected in water from Rock Creek Park, Washington, D.C., during base-flow synoptic, June 27–28, 2007. —Continued [<, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; U-DELETED, deleted value at lab--unable to determine; duplicate samples are in shaded cells for comparison; concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; Note: list of compounds not detected is shown in Appendix C] USGS station number Station name Date Time Compounds (micrograms per liter) Atrazine Bromacil Caffeine Camphor Cholesterol 3-beta- Copro- stanol 1,4-Dichloro- benzene 3,4-Dichloro- phenyl iso- cyanate 01647994 Rock Creek at MD/DC boundary 6/27/2007 655 E0.04 <0.2 <0.2 E0.04 E0.8 E0.5 E0.03 E1.40 0164799789 Fenwick Branch above Rock Creek 6/27/2007 825 E0.1 <0.2 <0.2 <0.2 <0.8 E0.4 <0.2 U-DELETED 01648001 Whittier Run above Rock Creek 6/27/2007 855 E0.01 E0.05 <0.2 <0.2 <0.8 <0.8 <0.2 U-DELETED 01648011 Luzon Branch at Joyce Road 6/27/2007 955 E0.04 <0.2 E0.08 <0.2 E0.5 <0.8 <0.2 U-DELETED 01648011 Luzon Branch at Joyce Road (duplicate) 6/27/2007 956 E0.05 <0.2 <0.2 <0.2 <0.8 <0.8 <0.2 U-DELETED 01648200 Piney Branch above Rock Creek 6/28/2007 910 E0.02 <0.2 <0.2 E0.02 E0.5 <0.8 E0.07 U-DELETED 01648200 Piney Branch above Rock Creek (duplicate) 6/28/2007 911 E0.02 <0.2 <0.2 E0.02 E0.5 <0.8 <0.2 U-DELETED 01649000 Rock Creek at Q Street 6/27/2007 1155 <0.2 <0.2 <0.2 <0.2 E0.8 E0.6 E0.04 U-DELETED 01649010 Rock Creek above M Street 6/27/2007 1240 E0.02 <0.2 E0.1 <0.2 <0.8 <0.8 E0.01 U-DELETED Blank 6/28/2007 859 <0.2 <0.2 <0.2 <0.2 <0.8 <0.8 <0.2 U-DELETED
Water-Quality Data 21

Table 6. Concentrations of total organic wastewater compounds detected in water from Rock Creek Park, Washington, D.C., during base-flow synoptic, June 27–28, 2007.—Continued[<, less than; E, estimated result—compound was detected but value was less than the reporting level with lower precision; U-DELETED, deleted value at lab--unable to determine; duplicate samples are in shaded cells for comparison; concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; Note: list of compounds not detected is shown in Appendix C]

USGS

station 

number

Date

Compounds

(micrograms per liter)

Diethoxyoctylphenol

[OP2EO]

Diethyl 

phthalate

N,N-Diethylmetatoluamide 

[DEET]

Hexahydrohexamethyl 

cyclopentabenzopyran 

[HHCB]

5-Methyl1h-benzotriazole Metol- achlor Penta- chloro- phenol Tetrachlo- roethylene Tris(2-bu- toxyethyl) phosphate Tris(2- chloroeth- yl)phos- phate Tri- closan Tris(dichloro- isopropyl) phosphate, [FYROL PCF]

01647994 6/27/2007 <0.32 0.6 E0.1 <0.2 E0.3 E0.01 <0.8 <0.4 E0.1 E0.05 <0.2 E0.050164799789 6/27/2007 <0.32 <0.2 E0.04 <0.2 <1.6 E0.04 <0.8 <0.4 E0.1 E0.5 <0.2 E0.0301648001 6/27/2007 <0.32 <0.2 <0.2 <0.2 <1.6 E0.02 <0.8 <0.4 <0.2 <0.2 <0.2 <0.201648011 6/27/2007 E0.4 <0.2 E0.2 E0.1 E0.4 E0.02 <0.8 <0.4 E0.4 E0.04 E0.04 E0.0501648011 6/27/2007 E0.4 <0.2 E0.2 E0.1 <1.6 E0.02 <0.8 <0.4 E0.4 E0.04 E0.04 E0.0501648200 6/28/2007 <0.32 <0.2 E0.04 <0.2 <1.6 <0.2 E1.2 E0.1 <0.2 E0.05 <0.2 E0.0301648200 6/28/2007 <0.32 <0.2 E0.04 <0.2 <1.6 <0.2 <0.8 E0.02 <0.2 E0.05 <0.2 <0.201649000 6/27/2007 <0.32 <0.2 E0.03 <0.2 <1.6 <0.2 E0.2 E0.07 E0.1 <0.2 <0.2 E0.0401649010 6/27/2007 <0.32 <0.2 E0.07 <0.2 <1.6 <0.2 <0.8 E0.02 E0.2 E0.04 <0.2 <0.2Blank 6/28/2007 <0.32 <0.2 <0.2 <0.2 <1.6 <0.2 <0.8 <0.4 <0.2 <0.2 <0.2 <0.2
22 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 7. Concentrations of organic wastewater compounds detected in creek bottom sediment, Rock Creek Park, Washington, D.C., during base-flow synoptic June 27–28, 2007. [E, estimated result—compound was detected but value was less than the reporting level with lower precision; --, result not quantified at lab (analysis failed); concentrations above method reporting levels are shown in bold; MD, Maryland; DC, Washington, D.C.; USGS, U.S. Geological Survey; <, less than; Note: list of compounds not detected is shown in Appendix D] USGS station number Station name Date Time Compounds (micrograms per kilogram, dry weight) Anthra- cene 9,10 Anthra- quinone Benzo[a] pyrene Carba- zole Choles- terol 3-beta- Copros- tanol

p-Cresol Fluoran- thene HHCB [Galax- olide] Indole 1-Meth- yl-naph- thalene

01647994 Rock Creek at MD/DC 

boundary

6/27/2007 0650 E5 E8 E20 E5 <180 <350 E10 80 <40 E10 <40

0164799789 Fenwick Branch above 

Rock Creek

6/27/2007 0820 E30 E36 110 E20 <150 <300 <150 340 <30 E10 <30

01648001 Whittier Run above 

Rock Creek

6/27/2007 0850 80 130 280 E60 E590 <600 <300 800 <60 200 <60

01648011 Luzon Branch at Joyce 

Road

6/27/2007 0950 50 59 200 E30 <200 <400 <200 460 E8 E10 <40

01648200 Piney Branch above 

Rock Creek

6/28/2007 0905 60 70 220 E40 E330 E110 <180 460 <40 90 E6

01649000 Rock Creek at Q Street 6/27/2007 1150 30 35 100 E20 E190 <180 130 290 <20 60 <2001649010 Rock Creek above M 

Street

6/27/2007 1235 40 56 130 E30 E240 <180 100 410 <20 E30 <20

USGS

station 

number

Station name Date Time

Compounds

(micrograms per kilogram)

2-Methyl-naphthalene 3-Methyl- 1h-indole [Skatol] Naph- thalene Phenan- threne Phenol Bisphe- nol-A 4-Nonyl- phenol 4-t- Octyl- phenol Pyrene beta- Sitos- terol beta- Stigmas- tanol

01647994 Rock Creek at MD/DC 

boundary

6/27/2007 0650 <40 <40 <40 E20 <40 -- <520 <40 70 <350 <350

0164799789 Fenwick Branch above 

Rock Creek

6/27/2007 0820 <30 <30 <30 160 <30 -- <450 <30 270 <300 <300

01648001 Whittier Run above 

Rock Creek

6/27/2007 0850 <60 E10 <60 550 E130 -- E370 <60 720 E3,400 E630

01648011 Luzon Branch at Joyce 

Road

6/27/2007 0950 <40 <40 E10 210 <40 -- <600 <40 400 <400 <400

01648200 Piney Branch above 

Rock Creek

6/28/2007 0905 E10 <40 E20 210 E60 E630 E3,100 60 400 E500 <350

01649000 Rock Creek at Q Street 6/27/2007 1150 <20 <20 E20 140 <20 E5 <270 <20 240 <180 <1,00001649010 Rock Creek above M 

Street

6/27/2007 1235 <20 <20 30 220 <20 -- <270 <20 340 <180 <1,000
Water-Quality Data 23

Q Street between the Anderson study and this investigation 

showed that concentrations of each of the four compounds for 

this investigation (sampled in June 2007) were all less than 

one-fifth of the concentrations found in the Anderson study 

(sampled in August 1999). However, concentrations were not 

normalized to TOC, so comparisons may not be valid.

Stormwater-Quality Data

Two series of stormwater samples were collected at 

the Rock Creek at Joyce Road gaging station (fig. 2) using 

an automated sampler (American Sigma 900Max) that 

began sampling when a specified stage threshold value was 

exceeded. The first set of six samples was collected on June 

27–28, 2008, when the discharge at Joyce Road increased 

from 12 ft3/s to 736 ft3/s in a period of 5 hours (fig. 5a). Four 

of the six samples were analyzed for dissolved OWCs, and 

three were analyzed for total OWCs. Two of the six were 

analyzed for both dissolved and total OWCs. All six were 

analyzed for bacteria and TOC, and five were analyzed for 

suspended sediment. Results of the analysis for OWC concentrations in the Joyce Road stormwater samples are shown in 

Appendix E.

The second set of samples was collected on September 6, 

2008, when the discharge increased from 8 ft3/s to 1,970 ft3/s 

over 20 hours during tropical storm Hanna (fig. 5b). During 

the September 2008 sampling, four sets of samples were 

selected to be analyzed for bacteria, TOC, and OWCs based 

on the discharge. 

Most OWC analyses were performed on filtered water, 

as the analyses for dissolved OWCs generally had lower 

detection limits. A comparison was made between the number 

of detections found in all of the dissolved and total OWC 

stormwater samples collected. Not counting duplicate or blank 

analyses, between the two storms, there were eight environmental samples analyzed for concentrations of dissolved 

OWCs, and four samples analyzed for concentrations of total 

OWCs, and the distribution of the results is shown below:

Sample type

Total 

number of 

results with 

“E” values1

Total number 

of results with 

detections 

above the MRL

From eight filtered (dissolved) 

samples 91 22

From four unfiltered (whole-water) 

samples 73 16

1

 “E” values are estimated concentrations typically below the minimum 

reporting level (MRL).

Although the filtered samples had generally lower MRLs, 

the samples that were analyzed for total concentrations had 

a greater number of detections, including both estimated 

concentrations and concentrations above the MRLs. The 

greater number of detections is likely due to mobilization and 

suspension of sediments during higher flows. Bed sediments 

may represent a substantial pool of OWCs that are periodically 

mobilized by flows with sufficient shear stresses. The majority 

of detected OWCs were present at estimated concentrations 

below the MRLs in both filtered and whole-water analyses. 

Concentrations of OWCs in the stormwater samples and a list 

of all the OWCs analyzed are shown in Appendix E. A summary of the compounds detected in the stormwater samples 

and their detection frequencies are shown in table 8. 

Of the OWCs that were detected in the storm samples 

from the Joyce Road station, seven of the dissolved OWCs 

and seven of the total OWCs that were detected also were 

detected in each of the seven samples from bottom sediment 

(table 7), indicating that these compounds are prevalent 

throughout much of the basin, and may be more indicative of 

the effects of storm runoff over urban areas than runoff from 

CSOs or leaky sewer lines. The compounds are listed in 

table 9. 

Two water samples from each of the two storms at the 

Joyce Road station were analyzed for dissolved antibiotics 

and pharmaceuticals by the USGS OGRL. Of the 33 pharmaceutical compounds that were analyzed for each of the 4 

storm samples, only 1 compound was detected, just above 

the detection level (table 10). Carbamazepine was detected 

at 0.006 μg/L, just slightly above the detection level of 0.005 

μg/L. Carbamazepine is an anticonvulsant drug used to treat 

epilepsy, bipolar disorder, and ADHD, and it reduces abnormal 

excitement in the brain. The presence of the compound was 

confirmed by the analyst after the analysis of that sample as 

a routine internal lab duplicate. The OGRL also reported that 

carbamazepine is one of the most widely detected compounds 

in surface water in the emerging contaminant studies that they 

have conducted (Julie Dietze, USGS, written commun., 

March 2009).

Stormwater samples from the Joyce Road site were 

analyzed for Escherichia coli (E. coli) and total coliform 

bacteria and the results are presented in Appendix E. These 

data show high concentration ranges that are typical of other 

urban sites in the Washington, D.C. metropolitan area [USGS 

stations Paint Branch (01649190), Northeast Branch Anacostia 

River (01649500), and Northwest Branch Anacostia River 

(01651000)] where the USGS currently conducts storm- and 

base-flow water-quality sampling. E. coli are present in the 

intestines of humans and animals, and their presence in high 

concentrations usually indicates the presence of untreated or 

poorly treated wastewater in the environment. Exposure to 

E. coli can cause infections or disease in humans. Maximum 

concentrations occurred during the peak flow of storm events.
24 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Figure 5. Discharge and sample times from Rock Creek at Joyce Road, Washington, D.C., (A) June 27–28, 

2008 and (B) September 6–7, 2008.
Water-Quality Data 25

Table 8. Summary of dissolved- and total-organic-wastewater-compound concentrations in stormwater samples collected from Rock 

Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued

[μg/L, micrograms per liter; E, estimated result—compound was detected but value was less than the reporting level with lower precision; v, a substantial 

amount of the compound was detected in an associated blank and may not be a valid detection; duplicate samples were not double counted; Note: compounds 

are listed in order of rank by total number of detections]

8 Sets of samples collected for 

filtered analysis

Number of E 

values

Number of 

concentrations 

above method 

reporting levels

Total number of 

detections

Maximum value 

(μg/L)

Number of 

sampled 

sediment sites 

with detections2

Results from filtered (dissolved) analyses1

N,N-Diethyl-meta-toluamide [DEET] 14 8 8 0.56 0

9,10-Anthraquinone 8 0 8 E0.13 7

Camphor 0 8 8 E0.069 0

Caffeine 0 8 8 0.53 0

Fluoranthene 8 0 8 E0.027 7

Isophorone 8 0 8 E0.054 0

Pyrene 8 0 8 E0.022 7

Tris(2-chloroethyl)phosphate 6 2 8 E0.14 0

Tris(dichloroisopropyl)phosphate 8 0 8 E0.15 0

Triphenylphosphate 6 0 6 E0.051 0

Benzophenone 4 0 4 E0.066 0

3-beta Coprostanol 3 0 3 E0.55 7

5-Methyl-1H-benzotriazole 3 0 3 E0.37 0

Carbazole 3 0 3 E0.032 7

Cholesterol 3 0 3 E0.92 7

Metolachlor 3 0 3 E0.025 0

Phenanthrene 3 0 3 E0.024 7

Triethylcitrate 3 0 3 E0.030 0

Cotinine 2 0 2 E0.11 0

Naphthalene 2 0 2 E0.025 4

Tribromomethane 2 0 2 E0.013 0

4-tert-Octylphenol monoethoxylate 1 0 1 E0.072 0

beta-Stigmastanol 1 0 1 E0.99 1

Bisphenol A 1 0 1 E0.12 2

Hexahydrohexamethylcyclopentabenzopyran 

[HHCB]

1 0 1 E0.013 1

Tetrachloroethene 1 0 1 E0.011 0

Tris(2-butoxyethyl)phosphate 9 v 0 0 E0.46 0
26 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Table 8. Summary of dissolved- and total-organic-wastewater-compound concentrations in stormwater samples collected from 

Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued

[μg/L, micrograms per liter; E, estimated result—compound was detected but value was less than the reporting level with lower precision; v, a substantial 

amount of the compound was detected in an associated blank and may not be a valid detection; duplicate samples were not double counted; Note: compounds 

are listed in order of rank by total number of detections]

4 Sets of samples analyzed for 

unfiltered analysis

Number of E 

values

Number of 

concentrations 

above method 

reporting levels

Total number of 

detections

Maximum value 

(μg/L)

Number of 

sampled 

sediment sites 

with detections3

Results from whole-water analyses2

Caffeine 1 3 4 0.56 0

3,4-Dichlorophenyl isocyanate 4 0 4 E2.6 0

Anthracene 4 0 4 E0.96 7

Anthraquinone 2 2 4 0.048 7

Benzo[a]pyrene 2 2 4 0.77 7

beta-Sitosterol 4 0 4 E4 2

Carbazole 4 0 4 E0.13 7

Cholesterol 4 0 4 E2.70 4

Fluoranthene 0 4 4 1.42 7

Pentachlorophenol 4 0 4 E0.63 0

Phenanthrene 2 2 4 0.49 7

Pyrene 1 3 4 1.17 7

Tris(2-butoxyethyl)phosphate 3 1 4 E0.054 0

Tris(2-chloroethyl)phosphate 4 0 4 E0.14 0

Tris(dichloroisopropyl)phosphate 4 0 4 E0.11 0

Atrazine 3 0 3 E0.11 0

Camphor 3 0 3 E0.11 0

Triphenylphosphate 3 0 3 E0.059 0

Triclosan 2 0 2 E0.13 0

2 Methylnaphthalene 1 0 1 E0.016 1

5-Methyl-1H-benzotriazole 1 0 1 E0.36 0

Benzophenone 1 0 1 E0.10 0

beta-Stigmastanol 1 0 1 E1.06 1

bis (2-ethylhexyl)phthalate 1 0 1 E1.18 0

Bisphenol A 1 0 1 E0.28 2

N,N-Diethyl-meta-toluamide [DEET] 0 1 1 0.63 0

Diethylphthalate 0 1 1 0.34 2

para-Cresol 1 0 1 E0.10 3

Isophorone 1 0 1 E0.062 0

Phenol 1 0 1 E0.085 2

1

 See table 2 for concentrations by site and detection levels.

2

 See table 6 for concentrations by site and detection levels.

3

 Seven sites were sampled for concentrations of organic wastewater compounds in bottom sediments in June 2007. 

 This column compares presence of the compounds in bottom sediments to presence in stormwater samples.

 See table 7 for concentrations in bottom sediment samples.

4

 Low concentration detected in blank but does not affect the reported concentration.
Water-Quality Data 27

Table 9. Organic wastewater compounds that were detected 

in stormwater samples at Joyce Road that also were detected at 

each of the seven sediment-sampling sites.

Compounds detected 

at Joyce Road in 

filtered samples

Compounds detected 

at Joyce Road in 

unfiltered samples

9,10-Anthraquinone Anthracene

Carbazole Anthraquinone

Cholesterol Benzo[a]pyrene

3-beta Coprostanol Carbazole

Fluoranthene Fluoranthene

Phenanthrene Phenanthrene

Pyrene Pyrene

Passive-Sampler Data

Combined sets of SPMD and POCIS passive samplers 

were placed at the five sites that had the highest number of 

compounds detected during the June 2007 synoptic sampling 

in Rock Creek Park. The samplers were deployed on July 2, 

2008, and retrieved on July 29, 2008.

The POCIS samplers were designed to sample watersoluble (polar/hydrophilic) organic chemicals from aqueous 

environments whereas the SPMD samplers were designed to 

sample lipid- or fat-soluble (nonpolar/hydrophobic) semivolatile organic chemicals from water and air. For most chemicals 

over a 4-week deployment period, the SPMD and POCIS act 

as integrative samplers, allowing for the detection of very low 

levels of compounds that might be in the water. Results from 

the laboratories are expressed in nanograms per ampule of 

extracted material and are used primarily as screening tools to 

determine the presence of OWCs and their relative concentrations. Results for SPMD (table 11) have been converted to 

estimated ambient concentrations in units of pictograms per 

liter for most compounds based on modeling developed by 

Alaverez and others (2009). The raw concentrations in units of 

nanograms per ampule are in Appendixes F and G. The model 

was not applicable to POCIS samplers so results have not been 

converted to estimated ambient concentrations.

Semipermeable Membrane Devices (SPMD)

Samples from the SPMD were analyzed for suites of 

OWCs and PAHs (Appendix F) and pesticides 

(Appendix G). Estimated ambient concentrations are in table 

11 and raw concentrations for the samplers are in the appendixes. Of the OWCs and PAHs detected in the SPMD, anthracene, anthraquinone, benzo[a]pyrene, carbazole, fluoranthene, 

phenanthrene, and pyrene also were found in the stormwater 

samples at Joyce Road and in each of the creek-bottomsediment samples (table 9), indicating widespread distribution 

in the Park. Two indicators of wastewater, acetophenone and 

total para-nonylphenol, were detected in the SPMD 

(Appendix F), but were not detected in the sediment or other 

water samples. Acetophenone (used as a fragrance in soaps 

and detergents) was detected at each of the five passive-sampler sites. Para-nonylphenol is a detergent metabolite that was 

only found in the storm-sewer outfall below Fenwick Branch. 

Pesticides detected in the SPMD were dieldrin, benfluralin, dacthal, ethion, pendimethalin, and trifluralin 

(Appendix G), with concentrations of dieldrin roughly 2 to 3 

orders of magnitude higher than concentrations of other pesticides. The highest concentration of dieldrin was at the stormsewer-outfall site below Fenwick Branch; however, there was 

no lab result for dieldrin at the tributary near Bingham Drive 

for comparison.

A model was used to estimate concentrations in the water 

based on the concentrations in the extract in the ampules and 

the partitioning coefficient for each detected compound. The 

model was developed by USGS CERC and uses a spreadsheet 

called the SPMD Calculator, version 5 (updated 11/18/2007), 

based on calculations developed by Huckins and others 

(2006), and described by Alvarez and others (2009). Not all 

concentrations can be estimated by use of the model, as it is 

not valid for compounds with very high or very low partitioning coefficients; however, this is generally not an issue 

as these compounds are not readily sampled by the SPMD. 

Estimated average water concentrations in picograms per liter 

are presented in table 11. 

Polar Organic Chemical Integrative Samplers 

(POCIS)

The EST laboratory in St. Joseph, Missouri, extracted 

the compounds from the sorbent materials into ampules and 

shipped the ampules to the NWQL for analysis of pesticides 

and OWCs. Two of the five sets of samples were split, and a 

portion of the split was sent to the USGS OGRL in Lawrence, 

Kansas, for analysis for antibiotics. The results from the 

NWQL analyses are shown in table 12. The results from the 

OGRL are shown in table 13.

Twenty-two different pesticides were detected at at least 

one of the five POCIS sites between two different laboratory 

schedules (table 12), with the greatest number of pesticides 

detected at Broad Branch above Soapstone Valley (19 pesticides between the two lab schedules). More than half of the 

pesticides detected at that site had higher concentrations than 

those at the other four sites (table 12). The site with the next 

greatest number of detections was Fenwick Branch above 

Rock Creek (17 pesticides). Of the 22 pesticides detected, 3 

also were detected in the SPMD samplers (dacthal, dieldrin, 

and trifluralin—Appendix G); however, these three pesticides 

were detected at more sites in the SPMD samples than in the 

POCIS samples. Three pesticides (benfluralin, ethion, and 

pendimethalin) were detected in SPMD samples at one or two 

of the five sites, but were not detected in the POCIS samples.
28 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 10. Concentrations of pharmaceuticals and antibiotics in stormwater samples collected from Rock Creek at Joyce Road, Washington, D.C., June 27 and September 6, 2008. [μg/L, micrograms per liter; <, less than; concentrations above method detection levels have bold values; * and italics indicates a degradation compound from that category product; USGS, U.S. Geological Survey] Pharmaceutical category Compound Sample date and time Pharmaceutical category Compound Sample date and time 6/27/2008 6:25 PM 6/27/2008 9:25 PM 9/6/2008 3:15 AM 9/6/2008 4:30 PM 6/27/2008 6:25 PM 6/27/2008 9:25 P.M. 9/6/2008 3:15 AM 9/6/2008 4:30 PM Concentration (μg/L) Concentration (μg/L) Pharmaceuticals Tetracyclines and degradation products* Carbamazepine1 <0.005 <0.005 0.0061 <0.005 Chlorotetracycline <0.010 <0.010 <0.010 <0.010 Ibuprofen <0.050 <0.050 <0.050 <0.050 *Epi-chlorotetracycline <0.010 <0.010 <0.010 <0.010

*Iso-chlorotetracycline <0.010 <0.010 <0.010 <0.010

Macrolides and degradation products* *Epi-iso-chlorotetracycline <0.010 <0.010 <0.010 <0.010

Azithromycin <0.005 <0.005 <0.005 <0.005 Doxycycline <0.010 <0.010 <0.010 <0.010Erythromycin <0.008 <0.008 <0.008 <0.008 Oxytetracycline <0.010 <0.010 <0.010 <0.010*Erythromycin-H

O2 <0.008 <0.008 <0.008 <0.008 *Epi-oxytetracycline <0.010 <0.010 <0.010 <0.010

Roxithromycin <0.005 <0.005 <0.005 <0.005 Tetracycline <0.010 <0.010 <0.010 <0.010Tylosin <0.008 <0.008 <0.008 <0.008 *Epi-tetracycline <0.010 <0.010 <0.010 <0.010Virginiamycin <0.005 <0.005 <0.005 <0.005 

Other antiobiotics

Quinolines Lincomycin <0.005 <0.005 <0.005 <0.005 

Ciprofloxacin <0.005 <0.005 <0.005 <0.005 Trimethoprim <0.005 <0.005 <0.005 <0.005 Lomefloxacin <0.005 <0.005 <0.005 <0.005 Chloramphenicol <0.100 <0.100 <0.100 <0.100Norfloxacin <0.005 <0.005 <0.005 <0.005 Ormetoprim <0.005 <0.005 <0.005 <0.005 Ofloxacin <0.005 <0.005 <0.005 <0.005 Sarafloxacin <0.005 <0.005 <0.005 <0.005 

Discharge (cubic feet per second)

(see figs. 5a and 5b) 225 716 74 1,790 Enrofloxacin <0.005 <0.005 <0.005 <0.005 

Sulfonamides Long-term (1930–2007) monthly discharge 

statisitics (cubic feet per second) for the

USGS gage on Rock Creek at Sherrill Drive

June September Sulfachloropyridazine <0.005 <0.005 <0.005 <0.005 

Sulfadiazine <0.100 <0.100 <0.100 <0.100 Mean monthly minimum 18.3 2.0Sulfadimethoxine <0.005 <0.005 <0.005 <0.005 Mean monthly average 64.9 46.8Sulfamethazine <0.005 <0.005 <0.005 <0.005 Mean monthly maximum 456.0 348.0Sulfamethoxazole <0.005 <0.005 <0.005 <0.005 Sulfathiazole <0.050 <0.050 <0.050 <0.050 

1 Carbamazepine is an anticonvulsant drug used to treat epilepsy, bipolar disorder, and ADHD, and it reduces abnormal excitement in the brain.
Water-Quality Data 29

Table 11. Estimated average water concentrations from the Semipermeable Membrane Devices (SPMD) deployed in Rock Creek 

Park, Washington, D.C., July 2 through 29, 2008.—Continued

[pg/L, picograms per liter; PAH, polycyclic aromatic hydrocarbon; an ‘E’ before a value indicates an estimated concentration near the detection limit for that 

compound; a “v” in place of a concentration indicates that the value is questionable because of lab or field contamination; a “v” in front of a concentration 

indicates that as much as one third of the concentration may be due to blank contamination; U-DELETED indicates failure of analysis at the lab; results from 

U.S. Geological Survey National Water Quality Laboratory (NWQL)]

Stations where Semipermeable Membrane Devices (SPMD) were deployed

Max 

estimated 

average 

water 

concentration in field 

blank1

Portal 

Branch 

at 

Fenwick 

Branch 

(01647997)

Fenwick 

Branch 

above 

Rock 

Creek 

(0164799789)

Storm sewer 

to Rock 

Creek below 

Fenwick 

Branch 

(0164799790)

Rock 

Creek 

tributary 

near 

Bingham 

Drive 

(0164800550)

Broad 

Branch 

above 

Soapstone 

Valley 

(0164801540)

Discharge (cubic feet per second) 

(at deployment/at retrieval) -- 0.94/0.25 0.44/0.44 0.18/0.18 0.08/0.05 0.51/0.80

Organochlorine pesticides Possible or common uses Estimated average water concentrations (pg/L)

Benfluralin Herbicide 0 0 26 0 0 25

Dacthal Herbicide 0 21 18 0 17 E19

Dieldrin Insecticide 0 1,800 2,050 8,960 UDELETED2,020

Ethion Insecticide 0 0 0 30 0 0

Pendimethalin Herbicide 0 0 0 0 722 0

Trifluralin Herbicide 0 98 33 46 26 27

PAHs and related

heterocyclic compounds

Anthracene PAH 0 1,190 730 1,030 E264 E487

Anthraquinone Dyes for textiles, bird 

repellant

0 110,000 76,400 88,100 E19,500 27,900

Benzo[a]pyrene PAH, formed from incomplete combustion of 

organic materials

0 911 537 563 E159 E295

Benzophenone Fixative for soaps and 

perfumes

5,740 v v v v v

Carbazole Insecticide, dye, lubricants 0 E9,710 E6,230 7,570 0 0

Cholesterol Often a fecal indicator 3,790 v v v v v

d-limonene Fungicide, fragrances, and 

antimicrobial

91 v809 v3,540 v1,800 0 vE550

Fluoranthene PAH, asphalt, and coal tar 10 48,000 24,680 27,400 2,380 8,560

Hexahydrohexamethylcyclopentabenzopyran 

[HHCB]

Fabric softener, soaps, 

shampoos

25 2,630 v427 1,540 B v953

Para-nonylphenol-total Nonionic detergent 

metabolite

0 0 0 E2,660 0 0

Polybromodiphenyl ether Flame retardant 0 0 0 E280 0 E256

Phenanthrene PAH, component of tar, 

diesel fuel, dyes, drugs, 

explosives

64 15,500 8,480 13,600 E3,100 4,240

Pyrene PAH, asphalt, and coal tar 0 38,800 18,200 20,500 2,490 9,560

Triclosan Disinfectant, antimicrobial 0 0 0 2,590 0 686

Triphenyl phosphate Plasticizer, roofing paper, 

flame retardant

0 E165 0 0 0 0
30 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Table 11. Estimated average water concentrations from the Semipermeable Membrane Devices (SPMD) deployed in Rock Creek 

Park, Washington, D.C., July 2 through 29, 2008.—Continued

[pg/L, picograms per liter; PAH, polycyclic aromatic hydrocarbon; an ‘E’ before a value indicates an estimated concentration near the detection limit for that 

compound; a “v” in place of a concentration indicates that the value is questionable because of lab or field contamination; a “v” in front of a concentration 

indicates that as much as one third of the concentration may be due to blank contamination; U-DELETED indicates failure of analysis at the lab; results from 

U.S. Geological Survey National Water Quality Laboratory (NWQL)]

Compounds analyzed for, but not detected:

NWQL lab schedule 1433 NWQL lab schedule 2033

1,4-Dichlorobenzene 1-Napthol Malaoxon

3,4-Dichlorophenyl isocyanate 2,6-Diethylaniline Malathion

3-beta-Coprostanol 2-Chloro-2,6-diethylacetanilide Metalaxyl

4-Cumylphenol 2-Ethyl-6-methylaniline Methidathion

4-n-Octylphenol 3,4-Dichloroaniline Methyl azinphos

4-tert-Octylphenol 3,5-Dichloroaniline Methyl azinphos oxon

5-Methyl-1H-benzotriazole 4-Chloro-2-methylphenol Methyl paraoxon

Atrazine Acetochlor Methyl parathion

Butylated hydroxyanisole [BHA] Alachlor Metolachlor

Bisphenol A Atrazine Metribuzin

Bromacil Carbaryl Molinate

Bromoform Carbofuran Myclobutanil

Camphor Chlorpyrifos Oxyfluorfen

Carbaryl Chlorpyrifos oxygen analog Phorate

Chlorpyrifos cis-Permethrin Phorate oxon

Cotinine cis-Propiconazole Phosmet

Cumene Cyanazine Phosmet oxon

Diazinon Cylfuthrin Prometon

Dichlorvos Cypermethrin Prometryn

Diethylphthalate (found as lab contaminant) Deethylatrazine Pronamide

2-Butoxy-ethanol Desulfinylfipronil Propanil

Ethyl citrate Diazinon Propargites

Indole Diazoxon Simazine

Isoborneol Dichlorvos Tebuconazole

Isophorone Dicrotophos Tebuthiuron
Water-Quality Data 31

Table 11. Estimated average water concentrations from the Semipermeable Membrane Devices (SPMD) deployed in Rock Creek 

Park, Washington, D.C., July 2 through 29, 2008.—Continued

[pg/L, picograms per liter; PAH, polycyclic aromatic hydrocarbon; an ‘E’ before a value indicates an estimated concentration near the detection limit for that 

compound; a “v” in place of a concentration indicates that the value is questionable because of lab or field contamination; a “v” in front of a concentration 

indicates that as much as one third of the concentration may be due to blank contamination; U-DELETED indicates failure of analysis at the lab; results from 

U.S. Geological Survey National Water Quality Laboratory (NWQL)]

Compounds analyzed for, but not detected:

NWQL lab schedule 1433 NWQL lab schedule 2033

Isoquinoline Dimethoate Tefluthrin Compounds with blank 

contamination:

1-Methylnaphthalene

2-6-Dimethylnaphthalene

2-Methylnaphthalene

Diethylhexylphthalate

Naphthalene

The model does not work for these 

compounds:

Acetophenone

beta-Sitosterol

Caffeine

Phenol

Menthol Disulfoton Terbufos

Metalaxyl Disulfoton sulfone Terbufos-O-analog sulfone

Methyl salicylate Endosulfan I Terbuthylazine

Metolachlor Endosulfan sulfate Thiobencarb

N,N-diethyl-meta-toluamide [DEET] Eptam [EPTC] trans-Permethrin

total NP1EO Ethion monoxon trans-Propiconazole

total NP2EO Ethoprop Tribufos

OP1EO Fenamiphos

OP2EO Fenamiphos sulfone

para-Cresol Fenamiphos sulfoxide

Pentachlorophenol Fipronil

Prometon Fipronil degradate

Skatol Fipronil sulfide

Stigmastanol Fipronil sulfone

Tetrachloroethylene Fonofos

Tonalide [AHTN] Hexazinone

Tris(2-chloroethyl)phosphate Iprodione

Tris(dichlorisopropyl)phosphate Isofenphos

Tributyl phosphate lambda Cyhalothrin

Notes:

Concentrations from the lab originally were given in nanograms per amplule of extracted media. Estimates of concentrations in the streams used the 

SPMD Calculator version 5 created by the U.S. Geological Survey, Columbia Environmental Research Center, Columbia, MO, updated 11/18/2007.

Original concentrations in nanograms per ampule are given in Appendixes F and G.

Discharge measurements were taken at the deployment (July 2) and at the removal (July 29, 2008) of the SPMD.

1,000,000 picograms per liter equals 1 microgram per liter.
32 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Table 12. Normalized concentrations of organic wastewater compounds and pharmaceuticals detected in Polar Organic Chemical 

Integrative Samplers (POCIS) from five sites in Rock Creek Park, Washington, D.C., July 2 through 29, 2008.—Continued

[POCIS, polar organic chemical integrative sampler; “E” qualifier based on coelution with an interfering compound; “<” qualifier based on interference for 

that compound (if the compound was there, it would, at least, be below that level.); “v” before a concentration indicates the compound was detected in a blank; 

results from U.S. Geological Survey National Water Quality Laboratory (NWQL); nd, not detected; ng, nanograms; --, not available]

Extraction 

blank

Portal Branch 

above 

Fenwick 

Branch

Fenwick 

Branch 

above Rock 

Creek

Storm sewer 

to Rock 

Creek below 

Fenwick 

Branch

Rock Creek 

tributary at 

Bingham 

Drive

Broad 

Branch 

above 

Soapstone 

Valley

ANALYTES Normalized concentration (ng/POCIS)1

NWQL Schedule 2033–Detected Compounds

PESTICIDES

Atrazine nd 93.3 32.5 52.4 9.4 22.8

4-Chloro-2-methylphenol nd nd nd nd 4.8 nd

Dacthal nd 1.2 2.1 nd nd 1.9

Deethylatrazine nd 117 38.6 181 7.7 26.0

Desulfinylfipronil2 nd 4.7 7.2 nd nd 7.3

3,4-Dichloroaniline nd 28.0 6.6 618 <4.4 10.9

Dieldrin nd nd 7.2 nd nd 8.9

Fipronil nd 25.4 23.2 <28.7 nd 64.5

Fipronil sulfide nd 6.4 10.2 nd <8.9 11.4

Fipronil sulfone2 nd <9 10.9 nd 9.7 E 17.3

Metolachlor nd 33.3 18.5 nd <6.66 11.1

Myclobutanil <3.4 nd 11.3 nd 8.9 14.4

1-Napthol <3.5 56.3 9.7 282 15.7 10.9

Simazine nd 47.7 19.1 <40.6 nd 16.2

Tebuconazole nd nd nd 70.7 nd 73.5

Tebuthiuron nd nd nd 1,420 nd nd

Propiconazole, cis + trans nd nd nd nd nd 33.2

Trifluralin nd 3.7 6.1 nd nd 4.6

NWQL Schedule 1433– Detected Organic 

Wastewater Compounds

DETERGENTS AND DEGRADATES

Nonylphenol monoethoxylate [NP1EO]-total nd nd nd E408 nd E213

Nonylphenol diethoxylate [NP2EO]-total nd nd nd E2,490 nd E815

Octylphenyl monoethoxylate [OP1EO] nd nd nd E125 nd E50

Octylphenyl diethoxylalte [OP2EO] nd 89.3 nd 292 nd nd

para-Nonylphenol-total nd E202 E258 646 E237 E306

4-tert-Octylphenol nd 61.3 E37.9 E107 E37.1 nd

ORGANOPHOSPHATE ESTERS

Tris(2-chloroethyl)phosphate nd 328 194 E104 E33.1 83.0

Tris(dichlorisopropyl)phosphate nd 60.3 E78 nd nd E52

Tributyl phosphate nd nd nd E96.2 nd nd

Triphenyl phosphate nd nd nd nd nd E11.7
Water-Quality Data 33

Table 12. Normalized concentrations of organic wastewater compounds and pharmaceuticals detected in Polar Organic Chemical 

Integrative Samplers (POCIS) from five sites in Rock Creek Park, Washington, D.C., July 2 through 29, 2008.—Continued

[POCIS, polar organic chemical integrative sampler; “E” qualifier based on coelution with an interfering compound; “<” qualifier based on interference for 

that compound (if the compound was there, it would, at least, be below that level.); “v” before a concentration indicates the compound was detected in a blank; 

results from U.S. Geological Survey National Water Quality Laboratory (NWQL); nd, not detected; ng, nanograms; --, not available]

Extraction 

blank

Portal Branch 

above 

Fenwick 

Branch

Fenwick 

Branch 

above Rock 

Creek

Storm sewer 

to Rock 

Creek below 

Fenwick 

Branch

Rock Creek 

tributary at 

Bingham 

Drive

Broad 

Branch 

above 

Soapstone 

Valley

ANALYTES Normalized concentration (ng/POCIS)1

NWQL Schedule 1433–Detected Organic 

Wastewater Compounds–Continued

FRAGRANCE/FLAVORANTS

Acetophenone nd 610 352 263 253 401

Benzophenone E16.3 vE41.3 vE46.9 nd vE34.8 vE45.8

Hexahydrohexamethylcyclopentabenzopyran 

[HHCB] 

nd E18.2 nd E35.3 nd E17.5

3-Methyl-1H-indole [Skatol] nd nd E6.7 nd E9.9 E8.4

Tonalide [AHTN] nd E4.6 nd nd nd E6

PESTICIDES

Anthraquinone nd 79.3 E66 E86.0 nd E47.1

Atrazine nd 87.3 E42.3 nd nd nd

Bromacil nd nd nd E312 nd nd

Indole nd E45 E44.5 E133 119.3 E74

Metolachlor nd E32.8 E16.7 nd nd nd

N,N-Diethyl-meta-toluamide [DEET] nd 145 135 272 E68.7 278

POLYCYCLIC AROMATIC HYDROCARBONS

Anthracene nd 69.0 E47.5 E29.4 E18.9 E30.7

Carbazole nd E15.9 nd nd nd nd

Fluoranthene nd E15.9 E12.4 nd E9.9 E18.9

1-Methylnapthalene3 E2.4 vE10.3 vE5.5 nd vE12.1 nd

2-Methylnapthalene3 E4.4 vE16.4 vE9.5 vE9.48 vE24.5 vE6.7

Naphthalene3 E7.9 vE20.1 nd vE19.5 vE44.6 vE35.4

Phenanthrene E11.5 vE31.2 vE29.1 vE18.5 vE29 vE44.7

Pyrene nd E12.2 nd nd E7.5 E14.8

PHARMACEUTICALS

Caffeine nd 114.7 E98 257 nd 89.5

Cocaine -- E22.7 E14.7 E25.2 nd nd

Methyl salicylate nd E51.7 E33.9 E58.5 E103 nd

STEROLS

3-beta-Coprostanol nd nd nd nd nd E197

beta-Sitosterol nd nd nd nd nd E510

Cholesterol nd E563 E727 E934 E1,590 E1,460

Stigmastanol nd nd nd nd nd E319
34 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Table 12. Normalized concentrations of organic wastewater compounds and pharmaceuticals detected in Polar Organic Chemical 

Integrative Samplers (POCIS) from five sites in Rock Creek Park, Washington, D.C., July 2 through 29, 2008.—Continued

[POCIS, polar organic chemical integrative sampler; “E” qualifier based on coelution with an interfering compound; “<” qualifier based on interference for 

that compound (if the compound was there, it would, at least, be below that level.); “v” before a concentration indicates the compound was detected in a blank; 

results from U.S. Geological Survey National Water Quality Laboratory (NWQL); nd, not detected; ng, nanograms; --, not available]

Extraction 

blank

Portal Branch 

above 

Fenwick 

Branch

Fenwick 

Branch 

above Rock 

Creek

Storm sewer 

to Rock 

Creek below 

Fenwick 

Branch

Rock Creek 

tributary at 

Bingham 

Drive

Broad 

Branch 

above 

Soapstone 

Valley

ANALYTES Normalized concentration (ng/POCIS)1

NWQL Schedule 1433–Detected Organic 

Wastewater Compounds–Continued

INDUSTRIAL COMPOUNDS

Bisphenol A nd 320 208 386 E94 234

Diethylphthalate3 E30.9 116 163 172 157 191

Diethylhexylphthalate3 74.7 340 425 442 243 710

2-butoxy-Ethanol nd 583 1,080 418 nd 1,050

Isophorone nd 62.0 E48.9 nd nd E74

5-Methyl-1H-benzotriazole nd 10,500 nd 1,850 1,240 nd

para-Cresol nd 510 329 1,740 1,430 510

Phenol 158.0 v1,130 v599 v709 v576 v895
Water-Quality Data 35

Table 12. Normalized concentrations of organic wastewater compounds and pharmaceuticals detected in Polar Organic Chemical 

Integrative Samplers (POCIS) from five sites in Rock Creek Park, Washington, D.C., July 2 through 29, 2008.—Continued

[POCIS, polar organic chemical integrative sampler; “E” qualifier based on coelution with an interfering compound; “<” qualifier based on interference for 

that compound (if the compound was there, it would, at least, be below that level.); “v” before a concentration indicates the compound was detected in a blank; 

results from U.S. Geological Survey National Water Quality Laboratory (NWQL); nd, not detected; ng, nanograms; --, not available]

ANALYTES NOT DETECTED

NWQL Schedule 1433 NWQL Schedule 2033 Pharmaceuticals

Benzo[a]pyrene Acetochlor Hexazinone Butalbital 

Butylated hydroxyanisole (BHA) Alachlor Iprodione Carisoprodol 

Bromoform Benfluralin Isofenphos Chloroxylenol 

Camphor Carbaryl Lambda-cyhalothrin Chlorpheniramine 

Carbaryl Carbofuran Malaoxon Codeine 

Chlorpyrifos 2-Chloro-2,6-diethylacetanilide Malathion Diazepan 

Cotinine Chlorpyrifos Metalaxyl Hydrocodone 

Cumene Chlorpyrifos oxygen analog Methidathion Methadone 

Diazinon cis-Permethrin Methyl azinphos Methocarbamol 

1,4-Dichlorobenzene Cyanazine Methyl azinphos oxon Metoxalone 

3,4-Dichlorophenyl isocyanate Cylfuthrin Methyl paraoxon Oxycodone 

Dichlorvos Cypermethrin Methyl parathion Phendimetrizine 

2,6-Dimethylnapthalene Diazinon Metribuzin

d-Limonene Diazoxon Molinate

Ethyl citrate 3,5-Dichloroaniline Oxyfluorfen

Isoborneol Dichlorvos Pendimethalin

Isoquinoline Dicrotophos Phorate

Menthol 2,6-Diethylaniline Phorate oxon

Metalaxyl Dimethoate Phosmet

PBDPE4-2 Disulfoton Phosmet oxon

Pentachlorophenol Disulfoton sulfone Prometon

4-Cumylphenol Endosulfan I Prometryn

4-n-Octylphenol Endosulfan sulfate Pronamide

Prometon Eptam [EPTC] Propanil

Tetrachloroethylene Ethion Propargites

Triclosan Ethion monoxon Tefluthrin

Ethoprop Terbufos

2-Ethyl-6-methylaniline Terbufos-oxygen-analog sulfone

Fenamiphos Terbuthylazine

Fenamiphos sulfone Thiobencarb

Fenamiphos sulfoxide trans-Permethrin

Fipronil degradate Tribufos

Fonofos

1

 Normalized concentrations describe concentration per site. Three POCIS were deployed at each site. At two sites, one or two POCIS were broken and 

unusable. The extraction process concentrates all analytes from all POCIS into one ampule to be analyzed. If three membranes at one site were extracted, 

and compared to one POCIS at another site, given equal concentrations in the source water, the site with three intact membranes would have three times the 

concentration of the site with one intact POCIS. Therefore, each site was normalized by dividing the concentration per ampule by the number of intact POCIS 

at each site.

2

 Recovery of lab spikes was low; indicates concentrations potentially lower than actual.

3

 These compounds are commonly found in the Semipermeable Membrane Devices (SPMD) that were deployed adjacent to the POCIS and are likely the 

source of the associated blank contamination.
36 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Table 13. Concentrations of pharmaceuticals and antibiotics from Polar Organic Chemical Integrated Samplers (POCIS) samples collected at two sites in Rock Creek Park, Washington, D.C., July 2 through 29, 2008. [ng/mL, nanograms per milliliter; <, less than; * and italics indicates a degradation compound from that category product; concentrations above the maximum reporting level are shown in bold; analyses performed by the Kansas Water Science Center, Organic Geochemistry Research Laboratory (OGRL)] Pharmaceutical category Compound Station name Pharmaceutical category Compound Station name Fenwick Branch above Rock Creek Rock Creek tributary near Bingham Drive Lab blank Fenwick Branch above Rock Creek Rock Creek tributary near Bingham Drive Lab blank Concentration (ng/mL) Concentration (ng/mL) Pharmaceuticals Tetracyclines and degradation products* Carbamazepine1 12 <1.0 <1.0 Chlorotetracycline <1.0 <1.0 <1.0 Ibuprofen <1.0 <1.0 <1.0 *Epi-chlorotetracycline <1.0 <1.0 <1.0

*Iso-chlorotetracycline <1.0 <1.0 <1.0

Macrolides and degradation products* *Epi-iso-chlorotetracycline <1.0 <1.0 <1.0

Azithromycin <1.0 <1.0 <1.0 Doxycycline <1.0 <1.0 <1.0Erythromycin2 1.12 <1.0 <1.0 Oxytetracycline <1.0 <1.0 <1.0*Erythromycin-H

O2

3 7.65 <1.0 <1.0 *Epi-oxytetracycline <1.0 <1.0 <1.0

Roxithromycin <1.0 <1.0 <1.0 Tetracycline <1.0 <1.0 <1.0Tylosin <1.0 <1.0 <1.0 *Epi-tetracycline <1.0 <1.0 <1.0Virginiamycin <1.0 <1.0 <1.0

Quinolines Other antiobiotics

Ciprofloxacin <1.0 <1.0 <1.0 Lincomycin <1.0 <1.0 <1.0Lomefloxacin <1.0 <1.0 <1.0 Trimethoprim <1.0 <1.0 <1.0Norfloxacin <1.0 <1.0 <1.0 Chloramphenicol <1.0 <1.0 <1.0Ofloxacin <1.0 <1.0 <1.0 Ormetoprim <1.0 <1.0 <1.0Sarafloxacin <1.0 <1.0 <1.0Enrofloxacin <1.0 <1.0 <1.0 Discharge (cubic feet per second)

Sulfonamides Before deployment on 7/02/2008 0.44 0.08

Sulfachloropyridazine <1.0 <1.0 <1.0 After deployment on 7/29/2008 0.44 0.05Sulfadiazine <1.0 <1.0 <1.0Sulfadimethoxine <1.0 <1.0 <1.0Sulfamethazine <1.0 <1.0 <1.0Sulfamethoxazole4 3.16 1.16 <1.0Sulfathiazole <1.0 <1.0 <1.0

1 Carbamazepine is an anticonvulsant drug used to treat epilepsy and bipolar disorder, ADHD, and 

reduce abnormal excitement in the brain.

2 Erythromycin is a common antibiotic, often used by individuals that are allergic to penicillin.

3 Erythromycin-H O is a degradation product of Erythromycin.

2

4 Sulfamethoxazole is an antibiotic.
Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park 37

Occurrence and Distribution of Organic 

Wastewater Compounds in Rock Creek 

Park

The 23 sites that were sampled in June 2007 during 

base-flow conditions were selected on the basis of the results 

of the TIR data from an overflight in January 2007, in cooperation with NPS personnel who were familiar with the Park 

infrastructure. The TIR data showed areas where warmer 

water was discharging to the creek potentially from either 

groundwater seeps, culverts, or leaky sewer lines. No leaky 

sewer lines were identified by the TIR data; however, discharge from some open pipes and a storm-sewer outfall was 

observed. Storm samples were collected from Rock Creek at 

Joyce Road using an automated sampler during storms in June 

and September 2008. The POCIS and SPMD passive samplers 

were placed at the five locations that had the greatest number 

of detections of OWCs based on results from the 23 base-flow 

samples. The number of detections was the primary criterion 

for locating the passive samplers because nearly all concentrations were estimated concentrations near or below detection 

limits, and using the total concentrations at each site would not 

represent a valid summation of the concentrations. The five 

sites selected for the passive-sampler placement were located 

in the north and west parts of the Park, not in areas to the east 

and south that were closer to areas affected by the combined 

CSS system (fig. 3); however, one of the five sites (storm 

sewer outfall to Rock Creek below Fenwick Branch—fig. 2) 

was a large (approximately 6-feet diameter) storm drain that 

was reportedly not connected to the CSO system, but had both 

physical evidence (gray-colored water discharging during base 

flow) and chemical evidence (results from synoptic sampling) 

that it released wastewater-affected runoff into Rock Creek. 

During the June 27–28, 2007 base-flow synoptic sampling, there were ubiquitous detections at estimated concentrations of dissolved OWC indicators such as DEET, caffeine, 

HHCB, and organophosphate flame retardants at more than 

half of the 23 sites sampled in Rock Creek Park (table 2). 

Concentrations of DEET and caffeine in the tributaries were 

variable, but in the main stem of Rock Creek, the concentrations were essentially the same throughout the length of the 

creek, indicating no increase in concentrations with distance 

downstream. HHCB was detected in 10 of the tributaries, 

but not at the main stem Rock Creek sites. Organophosphate 

flame retardants also were commonly detected in tributaries 

at concentrations less than 1 μg/L, but some samples had 

concentrations up to 5.6 μg/L (tributary to Fenwick Branch at 

Red Bud Lane, table 2). Concentrations of organophosphate 

flame retardants in the main stem Rock Creek were detected 

at estimated concentrations of 0.2 μg/L or less (table 2), and 

generally did not increase with distance downstream.

Samples collected at 7 of the 23 sites for whole-water 

analysis (tables 3 and 6) showed similar patterns for the presence of DEET and organophosphate flame retardants, but 

caffeine and HHCB were detected in whole water from only 1 

or 2 of the 7 sites. Cholesterol and coprostanol (both indicators of OWCs) were detected more often in the whole-water 

samples than in the dissolved samples, but at similar concentrations. Overall, most wastewater indicators in whole-water 

samples in the Park had concentrations similar to those found 

at the upstream sampling station at the MD/DC boundary, 

indicating that water quality remained constant with distance 

downstream in the Park. The occurrence of these chemicals 

during base-flow conditions indicates that there are sources of 

wastewater coming into the stream; the presence of caffeine 

may indicate the presence of untreated sewage (Phillips and 

Chalmers, 2009).

Creek-bottom sediments were collected for analysis 

of concentrations of OWCs from the same seven sites from 

which whole-water samples were collected (table 7). The 

main compounds found in samples collected from bed 

sediments were PAHs and these occurred at concentrations 

that were similar to those found in earlier studies in Rock 

Creek (Anderson and others, 2002; Miller and others, 2006). 

Cholesterol was found in most of the samples, likely partitioning there preferentially due to its hydrophobicity. There were 

some detections of OWCs in the creek-bottom sediments, 

including HHCB and nonylphenol, but no spatial patterns in 

their occurrence were discerned.

Concentrations of organic compounds in dissolved 

and whole-water samples were compared to water-quality 

guidelines for the protection of aquatic life (Canadian 

Council of Ministers of the Environment (CCME), 2007; 

U.S. Environmental Protection Agency, 2009). Guidelines or 

criteria do not currently exist for many of the OWCs; however 

a few of the CCME guidelines were exceeded, mainly in unfiltered storm samples, and included those for dichlorophenols 

(0.2 μg/L), benzo[a]pyrene (0.015 μg/L), phenanthrene (0.4 

μg/L), and pyrene (0.025 μg/L). CCME guidelines for the protection of aquatic life are given in parentheses for each compound, and results for stormwater sampling are presented in 

Appendix E. Concentrations of OWCs for sediment sampling 

were similar to concentrations found during previous sampling 

events (Anderson and others, 2002; Miller and others, 2006), 

but were not compared because TOC, necessary to normalize 

values for the comparison, was not measured on sediment in 

the current study.

The SPMD and POCIS passive-sampling devices consistently collected numerous indicators of wastewater including 

caffeine, plastic degradates and byproducts of plastic manufacturing, perfumes, detergents and detergent degradates, 

pesticides, and pharmaceuticals. Some of the compounds 

were similar to those found in the water samples and indicate 

that there are likely low-level sources of wastewater entering the stream, particularly at the storm-sewer outfall below 

Fenwick Branch. The presence of agricultural herbicides such 

as atrazine, metolachlor, trifluralin, and the atrazine metabolite deethylatrazine, indicates common usage within the 

basin. Simazine also was found, but this chemical is used for 
38 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

agriculture as well as non-selective weed control on roadsides, 

and thus may have multiple sources. Some of the pesticides 

found are indicative of more mixed domestic and turf usage, 

such as the herbicide dacthal (DCPA); fipronil, which is used 

for flea and tick control on animals; and fungicides, such as 

propiconazol and myclobutanil. Organophosphate flame retardants, and particularly tris(2-chlorethyl)phosphate, were found 

consistently in the SPMD samplers. These compounds, along 

with the nonyl- and octylphenols compounds, are indicators of 

wastewater. The station with the highest accumulated concentrations was the storm-sewer outfall below Fenwick Branch, 

indicating that there is a reasonable likelihood that this outfall 

is a source of wastewater contamination.

The storm samples collected with the automatic sampler 

at Joyce Road showed generally higher concentrations of 

OWCs during the second storm (September 6, 2008) than 

during the first storm (June 27–28, 2008), probably because 

the September storm had a higher peak discharge (1,970 ft3/s) 

than the June storm (736 ft3/s, Appendix E). Many of the same 

OWCs found in base-flow samples and in passive samplers 

were also found during the two storm events, with some 

exceptions, within errors, at similar concentrations. 

Anthraquinone, an animal/bird repellant often used to 

control geese on golf courses, was detected in all but the 

first dissolved June storm samples, at 8 of the 23 base-flow 

sites, in bottom sediment at the 7 bed-sediment sites, in 4 of 

5 POCIS samples, and in 5 of 5 SPMD samples. The overall 

toxicological risk from human exposure to anthraquinone is 

currently considered negligible by the U.S. Environmental 

Protection Agency (USEPA) (http://www.epa.gov/pesticides/

biopesticides/ingredients/factsheets/factsheet_122701.htm).

Atrazine is an herbicide that was detected in whole-water 

samples at six of the seven sites where whole-water samples 

were collected at estimated concentrations of up to 0.05 μg/L, 

but it was not detected in any of the dissolved synoptic samples. Sampling by Anderson and others (2002) showed similar 

concentrations at two of three surface-water sites in the Park, 

with no detection at the third site. The herbicide was detected 

in at least 20 percent of samples collected from the Potomac 

River at Washington, D.C., during 2003–05 (Brayton and others, 2007) at concentrations of up to 1.75 μg/L. Metolachlor is 

another commonly used herbicide that was detected at 10 of 

the 23 synoptic sites in filtered samples, and at 4 of the 7 sites 

in whole-water samples, at concentrations similar to those 

found by Anderson and others (2002). Both herbicides were 

detected in the storm samples from Joyce Road in most of the 

June samples, but they were not detected in the September 

storm samples. Typically, these pesticides are applied in the 

spring and early summer and concentrations in surface waters 

peak in the summer (Ator and others, 2004). Atrazine was 

detected at all five of the passive-sampler sites (table 12), and 

metolachlor was detected at four of the five passive-sampler 

sites in July 2008.

Carbaryl is an insecticide that was detected at three 

surface-water sites in the Park in 2000 (Anderson and others, 

2002) at concentrations above water-quality criteria for the 

protection of aquatic life; however, it was not detected in any 

of the base-flow samples, stormwater samples, or samples 

from the passive samplers during this investigation, possibly

indicating a reduction in local usage of this compound and the 

degradation of environmental residues. 

Caffeine, an indicator of wastewater effluent, and DEET, 

an insect repellant, were detected at most of the base-flow 

sampling sites and in all of the stormwater samples at Joyce 

Road, indicating the presence of compounds that are ubiquitous in the hydrologic system. Dissolved concentrations of 

caffeine and DEET in the two sets of storm samples are shown 

in figures 6a and 6b, along with the associated discharge and 

concentrations of TOC and suspended sediment. The concentration curves for suspended sediment and TOC generally 

follow the discharge curve. Dissolved concentrations of caffeine and DEET during the June 2008 storm generally rose 

through the storm (fig. 6a); however, during the September 

2006 storm, which had a discharge peak roughly twice that of 

the June storm, concentrations of caffeine and DEET peaked 

before the discharge peak, then gradually decreased as discharge remained high (fig. 6b, Appendix E), possibly reflecting differences between the intensities of these two storms.

DEET is a recalcitrant OWC that persists in the environment longer than many of the other OWCs (Focazio and 

others, 2008; Glassmeyer and others, 2005; Stackelberg and 

others, 2007). It also persists through the sewage-treatment 

process and can often be found in treated effluents. Caffeine is 

more easily degraded by wastewater-treatment processes and 

thus is more indicative of untreated waste in close proximity 

to sources of OWCs. During both storms, the concentration of 

DEET peaked early and stayed elevated over the course of the 

storms, not showing any dilution effect from the stormwater. 

This observation indicates storage of this compound in bed 

sediments that are stirred up and transported during the storms 

as well as the addition of new sources during surface runoff. 

The peak in the concentration of caffeine was delayed, not rising during the initial rising limb of the hydrograph. During the 

smaller June 2008 storm, the concentration of caffeine stayed 

elevated throughout the storm, but during the September 2008 

storm, the concentration decreased later in the storm as higher 

flow volumes from storm runoff diluted the stream water. A 

possible scenario for this observation would be sewer lines 

that leak slowly during base flow but, as storms build up head 

in the shallow unconfined water table, some of the residuals 

are flushed into the stream. In larger storms, after this initial 

residual is flushed out, and the stream water becomes diluted 

with runoff, then the concentration of caffeine declines. HHCB 

was generally not found in the storm samples, except for 

one low-level detection at the leading edge of the September 

storm. Like caffeine, this is a very easily degraded compound, 

and would have been expected to follow similar patterns, but 

perhaps was not found due to differences in detection limits.

Carbazole, a heterocyclic organic compound, has a wide 

variety of uses and was detected in the bed sediments at each 
Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park 39

Figure 6. Discharge and concentrations of total organic carbon (TOC), suspended sediment, caffeine, and 

DEET from Rock Creek at Joyce Road, Washington, D.C., (A) June 27–28, 2008 and (B) September 6, 2008. 

(Concentrations measured on a base-flow sample collected on June 27, 2007 are shown for comparison.)
40 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

of the seven bed-sediment sites in this study, and at each of 

the three sediment sites in the Anderson (2002) study. In this 

study, carbazole was detected in about one third of the dissolved stormwater samples, in each of the whole-water storm 

samples at Joyce Road, but at only 1 of the 23 base-flow sampling sites—at the storm-sewer outfall below Fenwick Branch. 

The SPMD samplers showed concentrations of carbazole at 

three of the five passive-sampler sites, including the stormsewer outfall below Fenwick Branch (Appendix F).

Fluoranthene and pyrene, PAHs found in coal tars and 

asphalts, were detected in all of the storm samples at Joyce 

Road, in samples from each of the seven sediment sites, and in 

about one third of the dissolved base-flow samples. High concentrations of each were accumulated in all five SPMD passive samplers over the period of five storms in July 2008 (table 

11). Phenanthrene, also a PAH found in coal tars and asphalts, 

was detected at each sediment site, and had high concentrations accumulated at each of the SPMD sites. Phenanthrene 

was not detected in dissolved samples during the first storm, 

but was detected in most of the dissolved samples during the 

second storm and in each of the whole-water samples from 

both storms.

PAHs were consistently found in the stormwater samples 

at Joyce Road, and are ubiquitous contaminants in Rock 

Creek Park. Each of the individual PAHs was found in higher 

concentrations in either sediment or whole-water samples than 

in the dissolved samples collected during base-flow conditions 

at the 23 synoptic sites, or in the Joyce Road stormwater 

samples. Sources of PAHs include combustion of fossil fuels, 

particles from tire wear, lubricating oils, and asphalts and coal 

tar sealants. Mahler and others (2005) suggested that coal 

tar sealants that are used on driveways and parking lots are a 

dominant source of PAHs in urban watersheds, but a detailed 

analysis of PAH sources in Rock Creek was not conducted as 

part of this study.

Isophorone is an organic solvent used in a wide variety of 

applications, and was detected in all the stormwater samples 

at Joyce Road, but in only 3 of the 23 samples analyzed for 

dissolved compounds at the base-flow sites, and in none of the 

whole-water analyses or bottom-sediment samples.

The USGS currently samples E. coli bacteria at the 

Rock Creek at Joyce Road gaging station as part of another 

study in cooperation with Montgomery County, Maryland. 

From March through September 2008, 34 water samples 

were collected, primarily during storms, and analyzed for 

concentrations of E. coli bacteria. The USEPA-recommended 

(1986) geometric mean densities for E. coli for freshwater 

recreational areas are not to exceed 126 colony forming units 

(CFU) per 100 mL (criteria vary by state). Of the 34 samples 

collected during that time period, the concentration in only 1 

water sample collected at Joyce Road was below the criterion, 

and the median concentration was 12,000 MPN (most 

probable number of colonies per 100 mL; U.S. Geological 

Survey, 2009).

Summary and Conclusions

The U.S. Geological Survey, and the National Park 

Service Police Aviation Group, conducted a high-resolution, 

low altitude aerial thermal infrared survey of the Washington, 

D.C. section of Rock Creek Basin within the Park boundaries 

to identify specific locations where warm water from seeps or 

pipes was discharging to the creek. Twenty-three stream sites 

in Rock Creek Park were selected based on the thermal infrared images. The 23 sites were sampled during June 2007 and 

samples were analyzed for concentrations of organic wastewater compounds (OWCs). Two sets of stormwater samples 

were collected at the Rock Creek at Joyce Road gaging station 

using an automated refrigerated sampler that began sampling 

when a specified stage threshold value was exceeded. The first 

set of storm samples was collected on June 27–28, 2008, and 

the second set of samples was collected on September 6, 2008. 

Passive-sampler devices, which accumulate organic wastewater compounds and pesticides over the duration of deployment, 

were placed in July 2008 at the five locations that had the 

greatest number of detections of OWCs from the June 2007 

base-flow sampling. 

During the 2007 base-flow synoptic sampling, there were 

frequent detections at estimated concentrations of dissolved 

organic wastewater indicator compounds such as DEET 

(insect repellant), caffeine (stimulant), HHCB (galaxolide, a 

common fragrance in cosmetics and detergents), and organophosphate flame retardants at over half of the 23 sites sampled 

in Rock Creek Park. Concentrations of DEET and caffeine 

in the tributaries were variable, but in the main stem of Rock 

Creek, the concentrations were essentially the same throughout the length of the creek, indicating no increase in concentrations with distance downstream. HHCB, an indicator of 

wastewater, was detected in 10 of the tributaries, but not at the 

main-stem Rock Creek sites. Organophosphate flame retardants also were commonly detected in tributaries at concentrations less than 1 microgram per liter, but some samples had 

concentrations up to 5.6 micrograms per liter. Concentrations 

of organophosphate flame retardants in the main stem of Rock 

Creek were detected at estimated concentrations of 0.2 micrograms per liter or less and generally did not increase with 

distance downstream.

Samples collected at 7 of the 23 sites for whole-water 

analysis showed similar patterns for the presence of DEET 

and organophosphate flame retardants, but caffeine and HHCB 

were detected at only one or two of the seven sites sampled for 

whole-water analyses. Cholesterol and coprostanol (indicators 

of wastewater) were detected more often in the whole-water 

samples than in the dissolved samples, but at similar concentrations. Overall, concentrations of most wastewater indicators in whole-water samples in the Park were similar to the 

concentrations found at the upstream sampling station at the 

Maryland/Washington, D.C. boundary, indicating little change 

in concentration with distance downstream in the Park.
References Cited 41

Carbaryl is an insecticide that was detected at three 

surface-water sites in the Park in 2000 at concentrations above 

the water-quality criterion for the protection of aquatic life; 

however, it was not detected in any of the base-flow samples, 

stormwater samples, or samples from passive samplers during 

this investigation, possibly indicating a decrease in usage. 

Caffeine, an indicator of wastewater, and DEET were 

detected at most of the base-flow sampling sites, and in all 

of the stormwater samples at Joyce Road, indicating these 

compounds are nearly ubiquitous in the hydrologic system. 

Polycyclic aromatic hydrocarbons were the dominant class of 

organic compounds in the stormwater samples at Joyce Road. 

Each of the polycyclic aromatic hydrocarbons was found 

in higher concentrations in either sediment or whole-water 

samples than in the dissolved samples from the base-flow sampling at the 23 synoptic sites, or in the Joyce Road stormwater 

samples. 

Creek-bottom samples were collected from the same 

seven sites from which whole-water samples were also 

collected, and were analyzed for concentrations of OWCs. 

The main compounds found in samples collected from bed 

sediments were polycyclic aromatic hydrocarbons, and these 

occurred at concentrations that were similar to those found in 

earlier studies in Rock Creek.

The passive-sampling devices that were installed at the 

five sites with the highest number of detections during the 

base-flow sampling consistently collected numerous indicators 

of wastewater including caffeine, plastic degradates and 

byproducts of plastic manufacturing, perfumes, detergents and 

detergent degradates, pesticides, and pharmaceuticals. Some 

of the compounds were similar to those found in the water 

samples and indicate that there are likely low-level sources of 

wastewater entering the stream, particularly at the storm-sewer 

outfall below Fenwick Branch. 

Acknowledgments

The authors thank Sergeant Ronald Galey, formerly of the 

National Park Police Aviation Department, Washington, D.C., 

for planning and organizing the TIR overflight of Rock Creek 

Park. The authors also thank Officer Keaton Wright, who 

piloted the Park Police helicopter, and Officer Eric Haapapuro, 

who operated the TIR camera aboard the helicopter and supplied the images to the USGS. The authors also thank Terri 

Spencer of EST Labs in St. Joseph, Missouri, for exceptional 

technical assistance and for her help with the preparation 

and extraction in the lab of the SPMD and POCIS samplers, 

and David Alvarez and Edward Furlong of the USGS for 

guidance in the interpretation of the SPMD and POCIS data. 

Bill Yeaman, Natural Resource Specialist of Rock Creek Park, 

and Doug Curtis, Research Hydrologist of the National Park 

Service, National Capital Region, are thanked for technical 

assistance during the investigations within the Park.

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71 p.
44 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Zaugg, S.D., Smith, S.G., and Schroeder, M.P., 2006, Methods 

of analysis by the U.S. Geological Survey National Water 

Quality Laboratory—Determination of wastewater compounds in whole water by continuous liquid-liquid extraction and capillary-column gas chromatography/mass spectrometry: U.S. Geological Survey Techniques and Methods, 

book 5, chap. B4, 30 p.

Zaugg, S.D., Smith, S.G., Schroeder, M.P., Barber, L.B., and 

Burkhardt, M.R., 2006, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

Determination of wastewater compounds by polystyrenedivinylbenzene solid-phase extraction and capillary-column 

gas chromatography/mass spectrometry: U.S. Geological 

Survey Water-Resources Investigations Report 01–4186, 

37 p., available online at http://pubs.usgs.gov/wri/

wri014186/. 
Appendixes A–G 45

Appendixes A–G
46 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Appendix A. Selected images from thermal infrared flyover of Rock Creek Park, Washington, D.C., at dawn, January 31, 2007.

Image number Approximate location 

from fig. 2

U.S. Geological Survey

station number

U.S. Geological Survey 

station name/location of image

1 E 0164799790 Storm-sewer inflow to Rock Creek below Fenwick Branch

2 F 01648001 Whittier Run above Rock Creek

3 J 0164800550 Inflow upstream from Rock Creek tributary near Bingham Drive

4 L 01648011 Upstream end of Luzon Branch at Joyce Road

Image 1. Storm-sewer inflow to Rock Creek below 

Fenwick Branch.

Image 2. Whittier Run above Rock Creek.

near Bingham Drive.

Image 3. Inflow upstream from Rock Creek tributary Image 4. Upstream end of Luzon Branch at Joyce Road.
Appendixes A–G 47

Appendix A. Selected images from thermal infrared flyover of Rock Creek Park, Washington, D.C., at dawn, January 31, 2007.

—Continued

Image number Approximate location 

from fig. 2

U.S. Geological Survey

station number

U.S. Geological Survey 

station name/location of image

5 M 0164801540 Upstream end of Broad Branch above Soapstone Valley

6 R 01648390 Normanstone Creek above Rock Creek

7 U 01649000 Upstream from Rock Creek at Q Street

8 V 01649000 Pipe inflow to Rock Creek below P Street

Image 5. Upstream end of Broad Branch above 

Soapstone Valley.

Image 6. Normanstone Creek above Rock Creek.

Image 7. Upstream from Rock Creek at Q Street. Image 8. Pipe inflow to Rock Creek below P Street.
48 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Appendix B. Organic wastewater compounds analyzed in filtered surface-water samples from Rock Creek Park, Washington, D.C., 

June 27–28, 2007.

[Compounds detected are shown in bold. Detected concentrations shown in table 2; LRL, lower reporting limits for each compound are given after the compound, in micrograms per liter; U, result deleted by lab; analyzed by the U.S. Geological Survey National Water Quality Laboratory, Denver, CO, Schedule 

1433]

Compound LRL Compound LRL Compound LRL

Anthraquinone 0.16 N,N,-Diethyl-meta-toluamide [DEET] 0.2 5-Methyl-1H-benzotriazole 0.08

Acetophenone 0.1 Diazinon 0.16 3-Methyl-1H-indone [Skatol] 0.08

Acetyl hexamethyltetrahydronaphthalene [AHTN]0.5 1-4,Dichlorobenzene 0.08 Methyl Salicylate 0.18

Anthracene 0.08 Diethoxynonylphenol 5.0 Monoethoxyoctylphenol 1.0

Benzo[a]pyrene 0.12 Diethoxyoctylphenol 1.0 4-Nonylphenol 1.8

Benzophenone 0.18 2-6,Dimethylnaphthalene 0.2 Naphthalene 0.1

beta-Stigmastanol 2.0 Ethoxyoctylphenol 1.0 4-Octylphenol 0.16

Bromacil 0.4 Fluoranthene 0.08 4-tert-Octylphenol 0.1

3-Butyl-4-hydroxyanisole [BHA] 0.6 Hexahydrohexamethylcyclopentabenzopyran [HHCB]0.5 Phenanthrene 0.1

Caffeine 0.2 Indole 0.14 Phenol 0.4

Camphor 0.1 Isoborneol 0.06 Prometon 0.4

Carbaryl 1.0 Isophorone 0.1 Pyrene 0.08

Carbazol 0.08 Isopropylbenzene [Cumene] 0.1 beta-Sitosterol 2.0

Chlorpheniramine 0.04 Isoquinoline 0.4 Tetrachloroethylene 0.2

Chlorpyrifos 0.2 d-Limonene 0.1 Tribromomethane 0.1

Cholesterol 1.0 Metalaxyl 0.2 Tributyl phosphate 0.2

3-beta-Coprostanol 1.6 Metaxalone 4.0 Tris(2-butoxyethyl)phosphate 0.05

Bisphenol A U Methadone 0.4 Triclosan 0.2

Butalbital 0.4 1-Methylnaphthalene 0.1 Tris(2-chloroethyl)phosphate 

[FYROL CEF]

0.2

Cotinine 0.4 2-Methylnaphthalene 0.08 Tris(dichloroisopropyl)phosphate [FYROL PCF]

0.2

para-Cresol 0.18 Metolachlor 0.16 Triethyl citrate 0.4

4-Cumylphenol 0.14 Menthol 0.2 Triphenol phosphate 0.16
Appendixes A–G 49

Appendix C. Organic wastewater compounds for which surface-water samples were analyzed in unfiltered water in Rock Creek 

Park, Washington, D.C., June 27–28, 2007.

[Compounds detected for total analysis are shown in bold; see table 6 for concentrations of detected compounds; LRL, lower reporting limits for each 

compound are given after the compound, in micrograms per liter; analyzed by the U.S. Geological Survey National Water Quality Laboratory, Denver, CO, 

Schedule 4433]

Compound LRL Compound LRL Compound LRL

Acetophenone 0.4 Dichlorvos 0.2 Monoethoxyoctylphenol [OP1EO] 1

Acetyl hexamethyltetrahydronaphthalene 

[AHTN]

0.2 Diethoxyoctylphenol [OP2EO] 0.32 Naphthalene 0.2

Anthracene 0.2 Diethyl phthalate 0.2 para-Nonylphenol total 1.6

Anthraquinone 0.2 N,N,-Diethyl-meta-toluamide 

[DEET]

0.2 Phenanthrene 0.2

Atrazine 0.2 Diethoxynonylphenols-total 

[NP2EO]

3.2 Phenol 0.2

Benzo[a]pyrene 0.2 2,6-dimethylnaphthalene 0.2 4-n-Octylphenol 0.2

Benzophenone 0.2 Fluoranthene 0.2 4-tert-Octylphenol 0.2

Bisphenol A 0.4 Hexahydrohexamethylcyclopentabenzopyran [HHCB]0.2 Pentachlorophenol 0.8

Bromacil 0.2 Indole 0.2 Prometon 0.2

Bromoform 0.2 Isoborneol 0.2 Pyrene 0.2

Caffeine 0.2 Isophorone 0.2 beta-Sitosterol 0.8

Camphor 0.2 Isopropylbenzene [Cumene] 0.2 beta-Stigmastanol 0.8

Carbaryl 0.2 Isoquinoline 0.2 bis-(2-Ethylhexyl)phthalate [DEHP] 2

Carbazole 0.2 d-Limonene 0.2 3-tert-Butyl-4-hydroxyanisole 

[BHA]

0.2

Chlorpyrifos 0.2 Menthol 0.2 2,2’,4,4’-tetrabromodiphenyl ether 0.2

Cholesterol 0.8 Methylaxyl 0.2 Tetrachloroethylene 0.4

3-beta-Coprostanol 0.8 5-Methyl-1H-benzotriazole 1.6 Tris(2-butoxyethyl)phosphate 0.2

Cotinine 0.8 1-Methylnaphthalene 0.2 Tributyl phosphate 0.2

para-Cresol 0.2 2-Methylnapthalene 0.2 Tris(2-chloroethyl)phosphate 

[FYROL CEF]

0.2

4-Cumylphenol 0.2 3-Methyl-1H-indole [Skatol] 0.2 Triclosan 0.2

Diazinon 0.2 Methyl salicylate 0.2 Tris(dichloroisopropyl)phosphate 

[FYROL PCF]

0.2

1,4-Dichlorobenzene 0.2 Metolachlor 0.2 Triethylcitrate 0.2

3,4-Dichlorophenyl isocyanate 1.6 monoethoxynonylphenols-total 

[NP1EO]

0.2 Triphenyl phosphate 0.2
50 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08

Appendix D. Organic wastewater compounds for which creek-bottom-sediment samples were analyzed in Rock Creek Park, 

Washington, D.C., June 27–28, 2007.

[Compounds detected are shown in bold; see table 7 for concentrations of detected compounds; LRL range, either the lower reporting limit, or the range 

(min/max) of lower reporting limits for each compound are given after the compound, in micrograms per kilogram; analyzed by the U.S. Geological Survey 

National Water Quality Laboratory, Denver, CO, Schedule 5433]

Compound LRL 

range Compound LRL range Compound LRL range

Acetophenone 50/100 Diethoxynonylphenol 360/1,200 Metolachlor 20/60

Acetyl hexamethyltetrahydronaphthalene [AHTN]20/60 Diethoxyoctylphenol 20/60 Naphthalene 30

Anthracene 50 Diethylphthalate 40/120 4-Nonylphenol 270

9,10 Anthraquinone 50 2-6 Dimethylnaphthalene 20/60 4-n-Octylphenol 20/60

Atrazine 40/120 Ethoxynonylphenol 180/600 4-tert-Octylphenol 20

Benzo[a]pyrene 50 Ethoxyoctylphenol 90/300 Phenanthrene 50

Benzophenone 20/60 2-Ethylhexylphthalate 90/200 Phenol 20

Bromacil 180/600 Fluoranthene 50 Bisphenol A 50

3-Butyl 4-hydroxyanisole 50/120 Hexahydrohexamethylcyclopentabenzopyran [HHCB]20 Pyrene 50

Camphor 20/60 Indole 100 Prometon 20/60

Carbazole 50 Isoborneol 20/60 beta-Sitosterol 180

Chlorpyrifos 20/60 Isophorone 20/60 beta-Stigmastanol 300

Cholesterol 150 Isopropylbenzene 40/120 Tris(2-chloroethyl)phosphate 

[FYROL CEF]

40/120

3 beta-Coprostanol 180 Isoquinoline 40/120 Tris(dichloroisopropyl)phosphate 

[FYROL PCF]

40/120

para-Cresol 180 d-Limonene 20/60 Tributyl phosphate 20/60

4-Cumylphenol 20/60 Menthol 20/60 Triclosan 18/60

N,N-Diethyl-meta-toluamide 

[DEET]

40/120 1-Methylnaphthalene 20 Triphenyl phosphate 20/60

Diazinon 20/60 2-Methylnaphthalene 20 Tris(butoxyethyl)phosphate 50/180

1,4 Dichlorobenzene 18/60 3-Methyl-1H-indole [Skatol] 20
Appendixes A–G 51

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Instantaneous

discharge

(ft3/s)

Specific

conductance,

unfltrd,

lab

(μS/cm)

Organic

carbon,

unfltrd

(mg/L)

E. coli

(MPN/

100 

mL)

Total

coliform

(MPN/

100 mL)

1,4-Dichloro 

benzene, 

fltrd

(μg/L)

1 Methylnaphthalene, 

fltrd

(μg/L)

1 Methylnaphthalene, 

unfltrd 

(μg/L)

2,6-Dimethyl-naphthalene,

fltrd

(μg/L)

2,6-Dimethylnaphthalene,

unfltrd

(μg/L)

2

Methylnaphthalene,

fltrd

(μg/L)

2

Methylnaphthalene,

unfltrd

(μg/L)

6/23/2008 1150-blank -- -- E.2 -- -- <.1 <.1 -- <.1 -- <.1 --6/27/2008 1825 380 460 11.5 3,300 130,000 <.1 <.1 -- <.1 -- <.1 --6/27/2008 1925 650 278 20.7 44,000 >240,000 -- -- <.2 -- <.2 -- <.26/27/2008 2025 870 315 65.7 44,000 >240,000 <.1 <.1 <.4 <.1 <.4 <.1 <.46/27/2008 2125 865 242 40.7 41,000 >240,000 <.1 <.1 -- <.1 -- <.1 --6/28/2008 0125 350 158 26.1 46,000 >240,000 <.1 <.1 <.4 <.1 <.4 <.1 <.46/28/2008 0525 116 -- 13.5 34,000 >240,000 -- -- -- -- -- -- --9/6/2008 0315 100 -- 9.9 4,400 98,000 <.1 <.1 -- <.1 -- <.1 --9/6/2008 0500 107 -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 93 -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 90 -- 7.8 7,700 >240,000 <.1 <.1 -- <.1 -- <.1 --9/6/2008 831-dup -- -- -- -- -- <.1 <.1 -- <.1 -- <.1 --9/6/2008 1230 1610 -- 37.3 33,000 >240,000 <.1 <.1 -- <.1 -- <.1 --9/6/2008 1231-dup 1610 -- -- 55,000 >240,000 -- -- <.2 -- <.2 -- M9/6/2008 1630 1820 -- 17.7 23,000 >240,000 <.1 <.1 -- <.1 -- <.1 --9/6/2008 1631 -- -- 17.1 -- -- -- -- -- -- -- -- --9/6/2008 1635-blank -- -- -- -- -- <.1 <.1 -- <.1 -- <.1 --
52 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time 3,4-Di- chloro- phenyl iso- cyanate, unfltrd (μg/L) 3-beta- Copros- tanol, fltrd (μg/L) 3-beta- Copros- tanol, unfltrd (μg/L) 3-tert- Meth- yl- 1H- indole, fltrd (μg/L) 3-tert- Methyl- 1H- indole, unfltrd (μg/L) Butyl-4- hy- droxy- anisole, fltrd (μg/L) Butyl-4- hy- droxy- anisole, unfltrd (μg/L) 4 Cumyl- phenol, fltrd (μg/L) 4 Cumyl- phenol, unfltrd (μg/L) 4-EC- tetra- cycline HCl, fltrd (μg/L) 4-Epi- oxy- tetra- cycline, fltrd (μg/L) 4-Epi- tetra- cycline HCl, fltrd, (μg/L) 6/23/2008 1150 -- <1 -- <.08 -- <.6 -- <.1 -- -- -- -- 6/27/2008 1825 -- <1 -- <.08 -- <.6 -- <.1 -- <.01 <.01 <.01 6/27/2008 1925 E2.61 -- <.8 -- <.2 -- <.2 -- <.2 -- -- -- 6/27/2008 2025 E.061 <1 <2 <.08 <.4 <.6 <.4 <.1 <.4 -- -- -- 6/27/2008 2125 -- <1 -- <.08 -- <.6 -- <.1 -- <.01 <.01 <.01 6/28/2008 0125 E1.21 <1 <2 <.08 <.4 <.6 <.4 <.1 <.4 -- -- -- 6/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- 9/6/2008 0315 --

M -- <.08 -- <.6 -- <.1 -- -- -- --

9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 --

M -- <.08 -- <.6 -- <.1 -- -- -- --

9/6/2008 0831 -- <1 -- <.08 -- <.6 -- <.1 -- -- -- --9/6/2008 1230 -- <1 -- <.08 -- <.6 -- <.1 -- -- -- --9/6/2008 1231 E1.01 -- <.8 -- <.2 -- <.2 -- <.2 -- -- --9/6/2008 1630 --

M -- <.08 -- <.6 -- <.1 -- -- -- --

9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- <1 -- <.08 -- <.6 -- <.1 -- -- -- --

1 Indicates exceedance of water-quality guideline for the protection of aquatic life of 0.2 μg/L dichlorophenols (Canadian Council of Ministers of the Environment, 2007).
Appendixes A–G 53

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

4-nOctylphenol,

fltrd

(μg/L)

4-nOctylphenol,

unfltrd

(μg/L)

4-Nonylphenol, 

all

isomers,

fltrd

(μg/L)

4-

Nonylphenol,

all

isomers,

unfltrd

(μg/L)

4-Nonylphenol

diethoxylate,

fltrd

(μg/L)

4-Nonylphenol

diethoxylate,

unfltrd

(μg/L)

4-Nonylphenol

monoethoxylate,

unfltrd

(μg/L)

4-tertOctylphenol

diethoxylate,

fltrd

(μg/L)

4-tertOctylphenol

diethoxylate,

unfltrd

(μg/L)

3-tertOctylphenol 

monoethoxylate,

fltrd,

(μg/L)

4-tertOctylphenol

monoethoxylate,

unfltrd

(μg/L)

4-tertOctylphenol,

fltrd

(μg/L)

4-tertOctylphenol,

unfltrd

(μg/L)

6/23/2008 1150 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --6/27/2008 1825 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --6/27/2008 1925 -- <.2 -- <2 -- <3 <2.0 <.32 -- <1 -- -- <.26/27/2008 2025 <.16 <.4 <1 <3 <5 <6 <4.0 <.64 -- <2 -- <1 <.46/27/2008 2125 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --6/28/2008 0125 <.16 <.4 <1 <3 <5 <6 <4.0 <.64 -- <2 -- <1 <.46/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 <.16 -- <1 -- <5 -- -- <1 -- M -- <1 --9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --9/6/2008 0831 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --9/6/2008 1230 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --9/6/2008 1231 -- <.2 -- <2 -- <3 <2.0 -- <.32 -- <1 -- <.29/6/2008 1630 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.16 -- <1 -- <5 -- -- <1 -- <1 -- <1 --
54 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time 5-Meth- yl-1H- benzo- triazole, fltrd (μg/L) 5-Methyl- 1H- benzo- triazole, unfltrd (μg/L) Aceto- phe- none, fltrd (μg/L) Aceto- phe- none, unfltrd (μg/L) AHTN2

,

fltrd

(μg/L)

AHTN2

,

unfltrd

(μg/L)

Anhydroerthromycin,

fltrd

(μg/L)

9,10-

Anthracene,

fltrd

(μg/L)

Anthracene,

unfltrd

(μg/L)

9,10-

Anthraquinone,

fltrd

(μg/L)

Anthraquinone,

unfltrd

(μg/L)

Atrazine,

unfltrd

(μg/L)

6/23/2008 1150 <.08 -- <.4 -- <.5 -- -- <.1 -- <.2 -- --6/27/2008 1825 <.08 -- <.4 -- <.5 -- <.008 <.1 -- <.2 -- --6/27/2008 1925 -- <2 -- <.3 -- <.2 -- -- E.1 -- 0.3 E.116/27/2008 2025 <.08

M <.4 <.6 <.5 <.4 -- <.1 E.1 E.1 E.2 E.09

6/27/2008 2125 <.08 -- <.4 -- <.5 -- <.008 <.1 -- E.1 -- --6/28/2008 0125 <.08 <3 <.4 <.6 <.5 <.4 -- <.1

M E.1 E.2 E.08

6/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315

M -- <.4 -- <.5 -- -- <.1 --

M -- --

9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830

M -- <.4 -- <.5 -- -- <.1 -- E.1 -- --

9/6/2008 0831

M -- <.4 -- <.5 -- -- <.1 -- E.1 -- --

9/6/2008 1230 <.08 -- <.4 -- <.5 -- -- <.1 -- E.1 -- --9/6/2008 1231 -- <2 -- <.3 -- <.2 -- -- E.1 -- 0.5 <.209/6/2008 1630 <.08 -- <.4 -- <.5 -- -- <.1 -- E.1 -- --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.08 -- <.4 -- <.5 -- -- <.1 -- <.2 -- --

2 Acetyl hexamethyltetrahydronapthalene.
Appendixes A–G 55

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Azithromycin,

fltrd

(μg/L)

BDE

congener

47,

unfltrd

(μg/L)

Benzo

[a]

pyrene,

fltrd

(μg/L)

Benzo

[a]

pyrene,

unfltrd

(μg/L)

Benzophenone,

fltrd

(μg/L)

Benzophenone,

unfltrd

(μg/L)

betaSitosterol,

fltrd

(μg/L)

betaSitosterol,

unfltrd

(μg/L)

betaStigmastnol,

fltrd

(μg/L)

betaStigmastnol,

unfltrd

(μg/L)

Bis 

(2-ethylhexyl)

phthalate,

unfltrd

(μg/L)

Bisphenol A,

fltrd

(μg/L)

Bisphenol A,

unfltrd

(μg/L)

6/23/2008 1150 -- -- <.1 -- <.1 -- <2 -- <1 -- -- -- --6/27/2008 1825 <.005 -- <.1 -- <.1 -- <2 -- <1 -- -- -- --6/27/2008 1925 -- <.2 -- 0.43 -- <.2 -- E1 -- <.8 <2 -- <.46/27/2008 2025 -- <.4 <.1 E.43 <.1 <.4 <2 E2 <1 <2 <4 -- <.86/27/2008 2125 <.005 -- <.1 -- <.1 -- <2 -- <1 -- -- -- --6/28/2008 0125 -- <.4 <.1 E.23 <.1 <.4 <2 E2 <1 <.86 <4 -- <.86/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 -- -- <.1 -- E.1 -- <2 -- M -- -- -- --9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 -- -- <.1 -- E.1 -- <2 -- <1 -- -- M --9/6/2008 0831 -- -- <.1 -- M -- -- -- -- -- -- -- --9/6/2008 1230 -- -- <.1 -- E.1 -- -- -- -- -- -- -- --9/6/2008 1231 -- <.2 -- 0.83 -- E.1 -- E4 -- E1 E2 -- M9/6/2008 1630 -- -- <.1 -- M -- -- -- -- -- -- -- --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- -- <.1 -- <.1 -- -- -- -- -- -- -- --

3 Indicates exceedance of water-quality guideline for the protection of aquatic life of 0.015 μg/L for benzo(a)pyrene (Canadian Council of Ministers of the Environment, 2007).
56 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time Bisphe- nol A-d3, surrog, unfltrd (% recvy) Bisphe- nol A-d3 surrog, Sch 2033 & 8033 (% recvy) Broma- cil, fltrd (μg/L) Bro- macil, unfltrd (μg/L) Caffeine, fltrd (μg/L) Caf- feine, unfltrd (μg/L) Caffeine- 13C, surrog, unfltrd (% recvy) Caffeine- 13C surrog Sch 2033 & 8033, fltrd (% recvy) Camphor, fltrd (μg/L) Camphor, unfltrd (μg/L) Carbam- azepine, fltrd (μg/L) Carbaryl, fltrd (μg/L) Carbaryl, unfltrd (μg/L) 6/23/2008 1150 -- 0 <.4 -- <.1 -- -- 90.6 <.1 -- -- <1 -- 6/27/2008 1825 -- 16.8 <.4 -- E.1 -- -- 93

M -- <.005 <1 --

6/27/2008 1925 60.1 -- -- <.2 -- 0.6 75.8 -- -- E.1 -- -- <.26/27/2008 2025 58.2 30.1 <.4 <.4 0.4 E.3 74.3 85.6

M

M -- <1 <.4

6/27/2008 2125 -- 25.3 <.4 -- 0.3 -- -- 94

M -- <.005 <1 --

6/28/2008 0125 64.2 29.5 <.4 <.4 0.5 0.4 77.4 98.3

M <.4 -- <1 <.4

6/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 -- 20.3 <.4 -- 0.1 -- -- 90.8

M -- -- <1 --

9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 -- 38.7 <.4 -- 0.3 -- -- 85.9 E.1 -- -- <1 --9/6/2008 0831 -- 25.1 <.4 -- 0.3 -- -- 87.1 E.1 -- -- <1 --9/6/2008 1230 -- 20.3 <.4 -- 0.2 -- -- 92.5

M -- -- <1 --

9/6/2008 1231 90.8 -- -- <.2 -- 0.3 90.4 -- -- E.1 -- -- <.29/6/2008 1630 -- 42.3 <.4 -- 0.1 -- -- 69.6 E.1 -- -- <1 --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- 0 <.4 -- <.1 -- -- 83.3 <.1 -- -- <1 --
Appendixes A–G 57

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Carbazole,

fltrd

(μg/L)

Carbazole,

unfltrd

(μg/L)

Chloram

phenicol,

fltrd

(μg/L)

Chlrotetracycline,

fltrd

(μg/L)

Chlorpyrifos,

fltrd

(μg/L)

Chlorpyrifos,

unfltrd

(μg/L)

Cholesterol,

fltrd

(μg/L)

Cholesterol,

unfltrd

(μg/L)

Ciprofloxacin,

fltrd

(μg/L)

Cotinine,

fltrd

(μg/L)

Cotinine,

unfltrd

(μg/L)

Decafluorobiphenyl,

surrog,

unfltrd

(% recvy)

Decafluorobiphenyl,

surrog,

fltrd

(% recvy)

6/23/2008 1150 <.1 -- -- -- <.1 -- <1 -- -- <.4 -- -- 52.56/27/2008 1825 <.1 -- <.1 <.01 <.1 -- <1 -- <.005 <.4 -- -- 56.56/27/2008 1925 -- E.1 -- -- -- <.2 -- E1 -- -- <.8 48 --6/27/2008 2025 <.1 E.1 -- -- <.1 <.4 <1 E2 -- <.4 <2 39.7 62.16/27/2008 2125 M -- <.1 <.01 <.1 -- <1 -- <.005 <.4 -- -- 60.36/28/2008 0125 M E.1 -- -- <.1 <.4 <1 E3 -- <.4 <2 43.7 62.46/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 <.1 -- -- -- <.1 -- M -- -- E.088 -- -- 68.19/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 <.1 -- -- -- <.1 -- M -- -- <.4 -- -- 68.49/6/2008 0831 <.1 -- -- -- <.1 -- -- -- -- E.11 -- -- 67.19/6/2008 1230 <.1 -- -- -- <.1 -- -- -- -- <.4 -- -- 68.99/6/2008 1231 -- E.1 -- -- -- <.2 -- E3 -- -- <.8 52.4 --9/6/2008 1630 M -- -- -- <.1 -- M -- -- <.4 -- -- 66.59/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.1 -- -- -- <.1 -- -- -- -- <.4 -- -- 59.6
58 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time N,N,- Diethyl- meta- tolua- mide [DEET], fltrd (μg/L) N,N,-Di- ethyl-me- ta-tolua- mide [DEET], unfltrd (μg/L) Diazi- non, fltrd (μg/L) Diazi- non, unfltrd (μg/L) Dichlor- vos, unfltrd (μg/L) Diethyl phthal- ate, unfltrd (μg/L)

d-Limonene,

fltrd

(μg/L)

d-Limonene,

unfltrd

(μg/L)

Doxycycline,

fltrd

(μg/L)

Enrofloxacin,

fltrd

(μg/L)

Erythromycin,

fltrd

(μg/L)

Fluoranthene,

fltrd

(μg/L)

Fluoranthene,

unfltrd

(μg/L)

6/23/2008 1150 <.1 -- <.1 -- -- -- <.04 -- -- -- -- <.1 --6/27/2008 1825 0.2 -- <.1 -- -- -- <.04 -- <.010 <.005 <.008

M --

6/27/2008 1925 -- <.4 -- <.2 <.2 <.3 -- <.2 -- -- -- -- 0.76/27/2008 2025 0.2 <.3 <.1 <.4 <.4 <.4 <.04 <.4 -- -- --

M 0.8

6/27/2008 2125 0.3 -- <.1 -- -- -- <.04 -- <.010 <.005 <.008

M --

6/28/2008 0125 0.3 <.4 <.1 <.4 <.4 <.3 <.04 <.4 -- -- --

M 0.4

6/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 0.5 -- <.1 -- -- -- <.04 -- -- -- --

M --

9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 0.5 -- <.1 -- -- -- <.04 -- -- -- --

M --

9/6/2008 0831 0.6 -- <.1 -- -- -- <.04 -- -- -- --

M --

9/6/2008 1230 0.4 -- <.1 -- -- -- <.04 -- -- -- --

M --

9/6/2008 1231 -- 0.6 -- <.2 <.2 0.3 -- <.2 -- -- -- -- 1.49/6/2008 1630 0.3 -- <.1 -- -- -- <.04 -- -- -- --

M --

9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635

M -- <.1 -- -- -- <.04 -- -- -- -- <.1 --
Appendixes A–G 59

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Fluoranthened10,

surrog,

unfltrd

(% 

recvy)

Fluoranthened10,

surrog, 

Sch

20/8033

fltrd

(% recvy)

HHCB4,

fltrd

(μg/L)

HHCB4,

unfltrd

(μg/L)

Ibuprofen,

fltrd

(μg/L)

Indole,

fltrd

(μg/L)

Indole,

unfltrd

(μg/L)

Isoborneol,

fltrd

(μg/L)

Isoborneol,

unfltrd

(μg/L)

Isochlortetracycline,

fltrd

(μg/L)

Isoepichlorotetracycline,

fltrd

(μg/L)

Isophorone,

fltrd

(μg/L)

Isophorone,

unfltrd

(μg/L)

6/23/2008 1150 -- 94.2 <.5 -- -- <.1 -- <.1 -- -- -- <.1 --6/27/2008 1825 -- 94 <.5 -- <.050 <.1 -- <.1 -- <.01 <.01 M --6/27/2008 1925 48.2 -- -- <.2 -- -- <.2 -- <.2 -- -- -- <.26/27/2008 2025 39.6 84.2 <.5 <.4 -- <.1 <.4 <.1 <.4 -- -- M <.46/27/2008 2125 -- 93.3 <.5 -- <.050 <.1 -- <.1 -- <.01 <.01 M --6/28/2008 0125 50.1 93.7 <.5 <.4 -- <.1 <.4 <.1 <.4 -- -- M <.46/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 -- 83.9 M -- -- <.1 -- <.1 -- -- -- M --9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 -- 79.8 <.5 -- -- <.1 -- <.1 -- -- -- E.1 --9/6/2008 0831 -- 80 <.5 -- -- <.1 -- <.1 -- -- -- M --9/6/2008 1230 -- 83 <.5 -- -- <.1 -- <.1 -- -- -- M --9/6/2008 1231 46.1 -- -- <.2 -- -- <.2 -- <.2 -- -- -- E.19/6/2008 1630 -- 81.8 <.5 -- -- <.1 -- <.1 -- -- -- M --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- 80.2 <.5 -- -- <.1 -- <.1 -- -- -- <.1 --

4 Hexahydrohexamethylcyclopentabenzopyran or Galoxolide.
60 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time Iso- propyl- benzene fltrd (μg/L) Isoquin- oline, fltrd (μg/L) Iso- quino- line, unfltrd (μg/L) Linco- mycin, fltrd (μg/L) Lome- floxacin, fltrd (μg/L) Menthol fltrd (μg/L) Menthol unfltrd (μg/L) Meta- laxyl, fltrd (μg/L) Metalaxyl, unfltrd (μg/L) Methyl- salicylate, fltrd (μg/L) Methyl- salicy- late, unfltrd (μg/L) Metola- chlor, fltrd (μg/L) Metola- chlor, unfltrd (μg/L) 6/23/2008 1150 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 -- 6/27/2008 1825 <.1 <.2 -- <.005 <.005 <.2 -- <.1 -- <.1 --

M --

6/27/2008 1925 -- -- <.2 -- -- -- <.2 -- <.2 -- <.2 -- <.26/27/2008 2025 <.1 <.2 <.4 -- -- <.2 <.4 <.1 <.4 <.1 <.4

M <.4

6/27/2008 2125 <.1 <.2 -- <.005 <.005 <.2 -- <.1 -- <.1 --

M --

6/28/2008 0125 <.1 <.2 <.4 -- -- <.2 <.4 <.1 <.4 <.1 <.4 <.1 <.46/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --9/6/2008 0831 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --9/6/2008 1230 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --9/6/2008 1231 -- -- <.2 -- -- -- <.2 -- <.2 -- <.2 -- <.29/6/2008 1630 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.1 <.2 -- -- -- <.2 -- <.1 -- <.1 -- <.1 --
Appendixes A–G 61

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Naphthalene,

fltrd

(μg/L)

Norfloxacin,

fltrd

(μg/L)

Ofloxacin,

fltrd

(μg/L)

OxyOrmetoprim,

fltrd

(μg/L)

Tetracycline

fltrd

(μg/L)

paraCresol,

fltrd

(μg/L)

paraCresol,

unfltrd

(μg/L)

Pentachlorophenol,

unfltrd

(μg/L)

Phenanthrene,

fltrd

(μg/L)

Phenanthrene,

unfltrd

(μg/L)

Phenol,

fltrd

(μg/L)

Phenol,

unfltrd,

(μg/L)

Prometon,

fltrd,

(μg/L)

6/23/2008 1150 <.1 -- -- -- -- <.18 -- -- <.1 -- <.2 -- <.26/27/2008 1825 <.1 <.005 <.005 <.005 <.01 <.18 -- -- <.1 -- <.2 -- <.26/27/2008 1925 -- -- -- -- -- -- <.2 M -- 0.2 -- <.2 --6/27/2008 2025 <.1 -- -- -- -- <.18 <.4 M <.1 E.3 <.2 <.4 <.26/27/2008 2125 <.1 <.005 <.005 <.005 <.01 <.18 -- -- <.1 -- <.2 -- <.26/28/2008 0125 <.1 -- -- -- -- <.18 <.4 M <.1 E.1 <.2 <.4 <.26/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 <.1 -- -- -- -- <.18 -- -- M -- <.2 -- <.29/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 M -- -- -- -- <.18 -- -- M -- <.2 -- <.29/6/2008 0831 <.1 -- -- -- -- <.18 -- -- M -- <.2 -- <.29/6/2008 1230 M -- -- -- -- <.18 -- -- <.1 -- <.2 -- <.29/6/2008 1231 -- -- -- -- -- -- M M -- 0.55 -- E.1 --9/6/2008 1630 <.1 -- -- -- -- <.18 -- -- M -- <.2 -- <.29/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.1 -- -- -- -- <.18 -- -- <.1 -- <.2 -- <.2

5 Indicates exceedance of water-quality guideline for the protection of aquatic life of 0.4 μg/L for phenanthrene (Canadian Council of Ministers of the Environment, 2007).
62 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time Prome- ton, unfltrd (μg/L) Pyrene, fltrd (μg/L) Pyrene, unfltrd (μg/L) Rox- ithro- mycin, fltrd (μg/L) Saraflox- acin, fltrd (μg/L) Sulfa- chlor- pyrid- azine, fltrd (μg/L) Sulfa- diazine fltrd (μg/L) Sulfa- dimeth- oxine, fltrd (μg/L) Sulfa- methazine, fltrd (μg/L) Sulfa- methoxaxole, fltrd (μg/L) Sulfa- thiazole, fltrd (μg/L) Tetra- chloro- ethene, fltrd (μg/L) Tetra- cycline, fltrd (μg/L) 6/23/2008 1150 -- <.1 -- -- -- -- -- -- -- -- -- <.1 -- 6/27/2008 1825 --

M -- <.005 <.005 <.005 <.1 <.005 <.005 <.005 <.050 <.1 <.01

6/27/2008 1925 <.2 -- 0.66 -- -- -- -- -- -- -- -- -- --6/27/2008 2025 <.4

M 0.76 -- -- -- -- -- -- -- -- <.1 --

6/27/2008 2125 --

M -- <.005 <.005 <.005 <.1 <.005 <.005 <.005 <.050 <.1 <.01

6/28/2008 0125 <.4

M E.46 -- -- -- -- -- -- -- -- <.1 --

6/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 --

M -- -- -- -- -- -- -- -- -- <.1 --

9/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 --

M -- -- -- -- -- -- -- -- --

M --

9/6/2008 0831 --

M -- -- -- -- -- -- -- -- -- <.1 --

9/6/2008 1230 --

M -- -- -- -- -- -- -- -- -- <.1 --

9/6/2008 1231 <.2 -- 1.26 -- -- -- -- -- -- -- -- -- --9/6/2008 1630 --

M -- -- -- -- -- -- -- -- -- <.1 --

9/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- <.1 -- -- -- -- -- -- -- -- -- <.1 --

6 Indicates exceedance of water-quality guideline for the protection of aquatic life of 0.025 μg/L for pyrene (Canadian Council of Ministers of the Environment, 2007).
Appendixes A–G 63

Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued[<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples]

Date Time

Tribromomethane,

fltrd

(μg/L)

Tributyl

phosphate,

fltrd

(μg/L)

Tributyl

phosphate,

unfltrd

(μg/L)

Triclosan,

fltrd

(μg/L)

Triclosan,

unfltrd

(μg/L)

Triethyl

citrate

fltrd

(μg/L)

Triethyl

citrate

unfltrd

(μg/L)

Trimethoprim,

fltrd

(μg/L)

Triphenyl

phosphate,

fltrd

(μg/L)

Triphenyl

phosphate,

unfltrd

(μg/L)

Tris(2-

butoxyethyl)

phosphate,

fltrd

(μg/L)

Tris(2-

butoxyethyl)

phosphate,

unfltrd

(μg/L)

Tris(2-

butoxyethyl)

phosphate,

fltrd

(μg/L)

6/23/2008 1150 <.1 <.2 -- <.2 -- <.2 -- -- <.1 -- <.4 -- <.16/27/2008 1825 <.1 <.2 -- <.2 -- <.2 -- <.005 <.1 -- E.2v -- E.16/27/2008 1925 -- -- <.2 -- <.2 -- <.2 -- -- M -- 0.4 --6/27/2008 2025 M <.2 <.4 <.2 M <.2 <.4 -- M E.1 E.3v E.3 E.16/27/2008 2125 M <.2 -- <.2 -- <.2 -- <.005 M -- E.5v -- E.16/28/2008 0125 <.1 <.2 <.4 <.2 <.4 <.2 <.4 -- E.1 M E.4v E.4 E.16/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 <.1 <.2 -- <.2 -- M -- -- <.1 -- E.2v -- 0.19/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0830 <.1 <.2 -- <.2 -- <.2 -- -- M -- E.4v -- 0.19/6/2008 0831 <.1 <.2 -- <.2 -- M -- -- M -- E.4v -- 0.19/6/2008 1230 <.1 <.2 -- <.2 -- <.2 -- -- M -- E.5v -- E.19/6/2008 1231 -- -- <.2 -- M -- <.2 -- -- <.2 -- E.5 --9/6/2008 1630 <.1 <.2 -- <.2 -- M -- -- M -- E.2v -- E.19/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 <.1 <.2 -- <.2 -- <.2 -- -- <.1 -- E.2 -- <.1
64 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix E. Concentrations of organic wastewater compounds in stormwater samples from Rock Creek at Joyce Road, Washington, D.C. (station number 01648010), June and September 2008.—Continued [<, less than; --, data not available; E, estimated result—compound was detected but value was less than the reporting level with lower precision; M, presence verified but not quantified; tons/d, tons per day; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; MPN/100 mL, most probable number of detections per 100 milliliters; μg/L, micrograms per liter; surrog, surrogate; fltrd, filtered water sample; unfltrd, unfiltered water sample; % recvy, percent recovery of lab surrogate; μm, micrometers; a ‘v’ after a value shows that the compound was detected in a field blank and the results may be affected; tan shading indicates field blanks; gray shading indicates duplicate samples] Date Time Tris(2- chloro- ethyl) phos- phate, unfltrd (μg/L) Tris(di chloro- isopro- pyl) phos- phate, fltrd (μg/L) Tris(di- chloro- isopro- pyl) phos- phate, unfltrd (μg/L) Tylo- sin, fltrd (μg/L) Virginia- mycin, fltrd (μg/L) 1,4-Di- chloro- benzene, unfltrd (μg/L) Tri- bromo- methane, unfltrd (μg/L) Iso- propyl- benzene, unfltrd (μg/L) Naphth- alene, unfltrd (μg/L) Tetrachloro- ethene, unfltrd (μg/L) Sus- pended sediment (sieve diameter percent <62.5μm) Sus- pended sediment concen- tration (mg/L) Sus- pended sediment discharge (tons/d) 6/23/2008 1150 -- <.1 -- -- -- -- -- -- -- -- -- -- -- 6/27/2008 1825 -- E.1 -- <.008 <.005 -- -- -- -- -- -- 254 261 6/27/2008 1925 E.1 -- E.1 -- -- <.2 <.2 <.2 <.2

M -- 454 797

6/27/2008 2025 E.1 E.1 E.1 -- -- <.4 <.4 <.4 <.4

M -- 1,130 2,650

6/27/2008 2125 -- E.1 -- <.008 <.005 -- -- -- -- -- -- 1,200 2,8006/28/2008 0125 E.1 E.2 E.1 -- -- <.4 <.4 <.4 <.4 <.8 -- 637 6026/28/2008 0525 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 0315 -- E.1 -- -- -- -- -- -- -- -- -- 136 379/6/2008 0500 -- -- -- -- -- -- -- -- -- -- -- 120 359/6/2008 0645 -- -- -- -- -- -- -- -- -- -- -- 69 179/6/2008 0830 -- E.1 -- -- -- -- -- -- -- -- 94 103 259/6/2008 0831 -- E.1 -- -- -- -- -- -- -- -- -- -- --9/6/2008 1230 -- E.1 -- -- -- -- -- -- -- -- 52 2,150 9,3509/6/2008 1231 E.1 -- E.1 -- -- <.2 <.2 <.2 <.2 <.4 -- -- --9/6/2008 1630 -- E.1 -- -- -- -- -- -- -- -- 49 1,160 5,7009/6/2008 1631 -- -- -- -- -- -- -- -- -- -- -- -- --9/6/2008 1635 -- <.1 -- -- -- -- -- -- -- -- -- -- --
Appendixes A–G 65

Appendix F. Concentrations of organic wastewater compounds from Semipermeable Membrane Devices (SPMD) in Rock Creek Park, Washington, D.C., July 2–29, 2008.[NWQL, U.S. Geological Survey National Water Quality Laboratory; concentrations in nanograms per ampule unless otherwise indicated; ng/L, nanograms per liter; nd, not detected; E, qualifier based on performance during validation of method and/or below reporting level; <, less than qualifier based on interference for that compound (if the compound was there, it would, at least, be below that level); a “v” after a value indicates substantial concentrations were detected in field or lab blanks]

Compounds with 

detections

Portal Branch 

at Fenwick 

Branch

Fenwick 

Branch above 

Rock Creek

Storm sewer 

to Rock Creek 

below Fenwick 

Branch

Rock Creek 

tributary near 

Bingham Drive

Broad Branch 

above 

Soapstone 

Valley

Day zero 

blank

Field 

blank

SPMD 

NWQL spike

(percent 

recovered)

SPMD NWQL 

blank

(ng/L)

Concentration (nanograms/ampule)

Acetophenone E110 E76.3 E151 E118 E78.0 nd nd 111 ndAnthracene 294 180 255 E65.0 E120 nd nd 110 ndAnthraquinone 696 485 559 E124 177 nd nd 107 ndBenzo[a]pyrene 380 224 235 E66.3 E123 nd nd 108 ndBenzophenone nd nd nd E114v E83.7v E63.5 E99.1 112 ndCaffeine nd nd nd E56.6 nd nd nd 110 ndCarbazole E150 E96.3 117 nd nd nd nd 108 ndCholesterol E1,680v E796v E2,900v E1,440v E1,620v E3,150 E1,390 116 ndDiethylphthalate E135v E94.0v 591v 316v 246v 233 320 113 E.01Diethylhexylphthalate 1,050v 439v 3,280v 1,550v 1,270v 1,540 1,100 113 ndFluoranthene 20,800 10,700 11,900 1,030 3,710 E15.5 E22.0 110 ndHHCB [Galaxolide] 1170 190 684 E120v 424 E46.3 E56.4 116 ndd-Limonene 231v 1,010 514 nd E157v nd E130 112 nd2,6-Dimethylnapthalene E151v E64.8v 197v E47.8v nd E16.6 E38.0 109 nd1-Methylnapthalene E80.7v E56.9v E156v E84.5v E54.9v E30.6 E68.7 109 nd2-Methylnapthalene E145v E119v 198v 164v E105v E62.1 E144 108 ndNaphthalene E93.2v E92.9v E124v E136v E91.3v E37.1 E122 109 ndpara-Nonylphenol-total nd nd E1,180 nd nd nd nd 111 ndPBDPE4-2 nd nd E47.2 nd E43.3 nd nd NA ndPhenanthrene 3,880 2,120 3,400 775 1,060 E60.8 E80.1 107 ndPhenol E60.2v E56.3v nd E46.7v nd E24.2 E34.4 92 ndPyrene 14,600 6,840 7,720 936 3,600 E9.88 nd 111 ndbeta-Sitosterol E6,100 E993 E3,180 E4,440 nd nd nd 40 ndTriclosan nd nd 889 nd 236 nd nd 105 ndTriphenyl phosphate E48.1 nd nd nd nd nd nd 112 nd
66 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix F. Concentrations of organic wastewater compounds from Semipermeable Membrane Devices (SPMD) in Rock Creek Park, Washington, D.C., July 2–29, 2008.— Continued [NWQL, U.S. Geological Survey National Water Quality Laboratory; concentrations in nanograms per ampule unless otherwise indicated; ng/L, nanograms per liter; nd, not detected; E, qualifier based on performance during validation of method and/or below reporting level; <, less than qualifier based on interference for that compound (if the compound was there, it would, at least, be below that level); a “v” after a value indicates substantial concentrations were detected in field or lab blanks] Compounds without detections Atrazine 2-Butoxyethanol OPE2EO BHA Ethyl citrate para-Cresol Bisphenol A Indole 4-Cumylphenol Bromacil Isoborneol 4-n-Octylphenol Bromoform Isophorone 4-tert-Octylphenol Camphor Isoquinoline Pentachlorophenol Carbaryl Menthol Prometon Cotinine Metalaxyl Tris(dichlorisopropyl) phosphate Cumene 5-Methyl-1H-benzotriazole Skatol 3-beta-Coprostanol Methyl salicylate Stigmastanol Chlorpyrifos Metolachlor Tetrachloroethylene Diazinon N,N-Diethyl-meta-toluamide [DEET] Tonalide [AHTN] 1,4-Dichlorobenzene NP1EO-total Tris(2-chloroethyl) phosphate 3,4-Dichlorophenyl isocyanate NP2EO-total Tributylphosphate Dichlorvos OP1EO 
Appendixes A–G 67

Appendix G. Concentrations of pesticides from Semipermeable Membrane Devices (SPMD) in Rock Creek Park, Washington, D.C., July 2–29, 2008.[NWQL, U.S. Geological Survey National Water Quality Laboratory; concentrations in nanograms per ampule unless otherwise indicated; ng/L, nanograms per liter; nd, not detected; <, less than qualifier based on interference for that compound (if the compound was there, it would, at least, be below that level); U-DELETED based on interference where the compound elutes—cannot determine a “<” level for that compound; a “v” after a value indicates substantial concentrations were detected in field or lab blanks]

Compounds with 

detections

Portal Branch 

at Fenwick 

Branch

Fenwick 

Branch above 

Rock Creek

Storm sewer 

to Rock Creek 

below Fenwick 

Branch

Rock Creek 

tributary near 

Bingham 

Drive

Broad Branch 

above 

Soapstone 

Valley

Day zero 

blank

Field 

blank

SPMD NWQL 

blank

(percent 

recovered)

SPMD NWQL 

spike

(ng/L)

Concentration (nanograms/ampule)

Benfluralin <11.0 11.8 nd nd 11.2 nd nd nd 68.1Chlorpyrifos nd nd <142. <22.2v <67.9v <9.53 <9.62 nd 90.1Dacthal 4.0 3.4 <4.04 3.3 E3.6 nd nd nd 99.7Dieldrin 824 940 4,110 U-DELETED 927 nd nd nd 107.6Ethion nd nd 12.6 nd nd nd nd nd 67.0Methyl azinphos nd <11.3v <16.7v <12.5v <14.0v <13.9 <11.4 nd 44.4Metribuzin nd nd nd nd <103 nd nd nd 78.0Myclobutanil nd <23.9 <42.5 nd 0.0 nd nd nd 63.4Pendimethalin <111.v <49.3v nd 315v <70.8v <43.6 nd nd 72.4Trifluralin 44.4 14.7 20.6 11.9 12.2 nd nd nd 70.7Prometon nd nd nd nd <33.6 nd nd nd 80.1Tebuthiuron <67.4v <40.6v <106.v <21.5v <24.8v <11.9 <13.6 nd 73.9trans-Permethrin <36.1 <22.5 <33.8 nd nd nd nd nd 61.4

Surrogate compounds Percent recovered

alpha-HCH-d6 81.9 83.0 81.3 87.9 81.8 81.1 80.0 95.1 97.8Diazinon d10 123.1 118.9 121.0 121.2 115.5 107.3 106.0 68.5 93.1
68 Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08 Appendix G. Concentrations of pesticides from Semipermeable Membrane Devices (SPMD) in Rock Creek Park, Washington, D.C., July 2–29, 2008.—Continued [NWQL, U.S. Geological Survey National Water Quality Laboratory; ng/L, nanograms per liter; nd, not detected; <, less than qualifier based on interference for that compound (if the compound was there, it would, at least, be below that level); “U-DELETED” based on interference where the compound elutes. Cannot determine a “<” level for that compound; a “v” after a sample indicates substantial concentra- tions were detected in field or lab blanks.] Compounds without detections Acetochlor Dimethoate Lambda-cyhalothrin Propanil Alachlor Disulfoton Malaoxon Propargites Atrazine Disulfoton sulfone Malathion trans-Propiconazole Carbaryl Endosulfan I Metalaxyl Simazine Carbofuran Endosulfan sulfate Methidathion Tebuconazole 4-Chloro-2-methylphenol Eptam [EPTC] Methyl azinphos oxon Tefluthrin Chlorpyrifos oxygen analog Ethion monoxon Methyl paraoxon Terbufos 2-Chloro-2,6-diethylacetanilide Ethoprop Methyl parathion Terbufos-oxygen-analog sulfone Cyanazine 2-Ethyl-6-methylaniline Metolachlor Terbuthylazine Cylfuthrin Fenamiphos Molinate Thiobencarb Cypermethrin Fenamiphos sulfone 1- Napthol Tribufos Deethylatrazine Fenamiphos sulfoxide Oxyfluorfen Desulfinylfipronil Fipronil cis-Permethrin Diazinon Fipronil degradate Phorate Diazoxon Fipronil sulfide Phorate oxon 3,4-Dichloroaniline Fipronil sulfone Phosmet 3,5-Dichloroaniline Fonofos Phosmet oxon Dichlorvos Hexazinone Prometryn Dicrotophos Eprodione Pronamide 2,6-Diethylaniline Esofenphos cis-Propiconazole
Prepared by USGS West Trenton Publishing Service Center.

Edited by Valerie M. Gaine.

Graphics and layout by Timothy W. Auer.

For additional information, contact:

Director, MD-DE-DC Water Science Center

U.S. Geological Survey

5522 Research Park Drive

Baltimore, MD 21228

or visit our Web site at:

http://md.water.usgs.gov
Phelan, D.J., and Miller, C.V.—Occurrence and Distribution of Organic Wastewater Compounds in Rock Creek Park, Washington, D.C., 2007–08—Scientific Investigations Report 2010–5162

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