U.S. Department of the Interior 

GALE A. NORTON, Secretary 

U.S. Geological Survey 

Charles G. Groat, Director 

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

descriptive purposes only and does not imply endorsement 

by the U.S. Government. 

For additional information contact: 

District Chief 

U.S. Geological Survey 

8987 Yellow Brick Road 

Baltimore, MD 21237 

Copies may be purchased from: 

U.S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver, CO 80225-0286 
CONTENTS 

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

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

Purpose and scope .........................................................................................................................................................2

Previous investigations ..................................................................................................................................................6

Current investigation .....................................................................................................................................................6

Description of study area...............................................................................................................................................7

Geology.................................................................................................................................................................7

Hydrology .............................................................................................................................................................7

Precipitation ..........................................................................................................................................................7

Land-use patterns ..................................................................................................................................................8

Sources of fertilizers and pesticides to Rock Creek Park..............................................................................................9

Potential sources outside the park.........................................................................................................................9

Potential sources within the park ........................................................................................................................14

Acknowledgments.......................................................................................................................................................14

Methods of investigation......................................................................................................................................................21

Site selection................................................................................................................................................................21

Sampling and field methods ........................................................................................................................................21

Analytical methods ......................................................................................................................................................21

Quality assurance and quality control .........................................................................................................................22

Stream-channel classification ......................................................................................................................................22

Water-quality data ................................................................................................................................................................27

Synoptic surface-water sampling.................................................................................................................................27

Temporal surface-water sampling................................................................................................................................32

Sediment-quality data...........................................................................................................................................................37

Data analysis and comparison of stream-channel classifications.........................................................................................43

Summary and conclusions....................................................................................................................................................44

References cited ...................................................................................................................................................................44

Appendixes...........................................................................................................................................................................47

Appendix A: Results of analyses for:

A1. Dissolved pesticides for synoptic water-quality samples collected in June 1999,

and temporal water-quality samples collected from February 18, 1999 through

September 26, 2000 in surface water from Rock Creek, Washington, D.C. ...........................48

A2. Nutrients, major ions, and field parameters for synoptic sampling in June 1999,

and temporal sampling from February 18, 1999 through September 26, 2000

in surface water from Rock Creek, Washington, D.C. ...........................................................64

A3. Organic compounds measured in samples of bed sediment collected from

Rock Creek, Washington, D.C., August 1999 .........................................................................70

A4. Trace elements, major elements, and inorganic and organic carbon measured in samples

of bed sediment collected from Rock Creek, Washington, D.C., August 1999 ......................78

Appendix B: Laboratory code constituents and parameters for: 

B1. Schedule 2001, dissolved pesticides in water, from the U.S. Geological Survey

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................82

B2. Schedule 2050, dissolved pesticides in water, from the U.S. Geological Survey

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................84

B3. Schedule 2420, trace elements in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................85

iii 
11

3 

4 

5

6

-

8

9

Contents—Continued 

Appendix B: Laboratory code constituents and parameters for: 

B4. Schedule 2500, organic compounds in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................87

B5. Schedule 2701, major ions in water, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................90

B6. Schedule 2702, nutrients in water, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001.................................90

Appendix C: Selected transformation products from pesticides discussed in this report...............................................91

Figures 

1-2. Maps showing: 

1. Location of Rock Creek drainage basin and Rock Creek Park study area, Washington, D.C. ...............3

2. Locations of surface-water stations within the Rock Creek Park study area, Washington, D.C. ............4

3. Graph showing precipitation data measured at Dalecarlia Reservoir, near the Rock Creek Park

study area, Washington, D.C., for water years 1999 and 2000.....................................................................9

4. Map showing land use in the Rock Creek Basin, Washington, D.C. and Montgomery

County, Maryland .......................................................................................................................................10

5-14. Graphs showing: 

5. Concentrations of insecticides detected in synoptic water-quality samples in the Rock Creek Park

study area, Washington, D.C., June 1999 ...................................................................................................27

6. Concentrations of herbicides detected in synoptic water-quality samples in the Rock Creek Park

study area, Washington, D.C., June 1999 ...................................................................................................32

7. Total concentrations of herbicides and insecticides detected in synoptic water-quality samples 

in the Rock Creek Park study area, Washington, D.C., June 1999.............................................................32 

8. Stream discharge and total concentrations of insecticides at Rock Creek at Joyce Road

(station 01648010) for water years 1999 and 2000 in the Rock Creek study area,

Washington, D.C. .......................................................................................................................................33

9. Stream discharge and total concentrations of herbicides at Rock Creek at Joyce Road

(station 01648010) for water years 1999 and 2000 in the Rock Creek study area,

Washington, D.C. .......................................................................................................................................34

10. Stream discharge and total concentrations of herbicides used predominantly in urban/suburban

(2,4-D and MCPA) or agricultural (atrazine, cyanazine, and metolachlor) environments

for Rock Creek at Joyce Road (station 01648010) for water years 1999 and 2000

in the Rock Creek Park study area, Washington, D.C. ..............................................................................35

11. Ratios of selected insecticide concentrations to their respective aquatic criteria for samples 

collected from Rock Creek at Joyce Road (station 01648010) from October 1999 through

September 2000 in the Rock Creek Park study area, Washington, D.C. ...................................................36

12. Total concentrations of polycyclic aromatic hydrocarbons at the bed-sediment stations sampled

in the Rock Creek Park study area, Washington, D.C., August 1999 ........................................................37

13. Total concentrations of polychlorinated biphenyls at the bed-sediment stations sampled in the

Rock Creek Park study area, Washington, D.C., August 1999 ..................................................................42

14. Total concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT);

1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); and 1,1-dichloro-2,2-bis(p-chlorophenyl)

ethane (DDD) at the bed-sediment stations sampled in the Rock Creek Park study area,

Washington, D.C., August 1999 .................................................................................................................43

iv 
1

2

3

4

5

6

7

8

9

Tables 

1. Sample-collection dates, station identification numbers, and locations for synoptic water-quality,

temporal water-quality, and bed-sediment samples collected from Rock Creek, Washington, D.C.,

during water years 1999 and 2000 .........................................................................................................................5

2. Land-use statistics for the Rock Creek Basin in the Washington, D.C. area, and the entire

Rock Creek Basin in Washington, D.C. and Montgomery County, Maryland......................................................8

3. Estimated usage of selected pesticides in agricultural applications in Montgomery County, Maryland,

1996 and 1999 ......................................................................................................................................................11

4. Pesticides applied to Rock Creek Golf Course, Washington, D.C., during water years 1999 and 2000 .................15

5. Pesticides applied to Rock Creek Park, Washington, D.C., during water year 1999...............................................16

6. Pesticides applied to Rock Creek Park, Washington, D.C., during water year 2000...............................................18

7. Quality-assurance and quality-control data for pesticide analyses and selected transformation

products in surface-water samples collected from February 1999 through September 2000

Rock Creek, Washington, D.C. ...........................................................................................................................23

8. Quality-assurance and quality-control data for nutrient and major ion analyses in synoptic and

temporal surface-water samples from Rock Creek, Washington, D.C. ...............................................................26

9. Data-variable values measured in Rosgen stream-channel classification, data analyses, and interpretation...........26

10. Summary of contaminants in surface water at Rock Creek Park, Washington, D.C.,

during water years 1999 and 2000, and water-quality criteria for the protection of aquatic life .........................28

11. Summary of contaminants in bed sediment at Rock Creek Park, Washington, D.C.,

and published sediment-quality criteria for the protection of aquatic life............................................................38

v 
_____________________________________________________________________________________________________________________________________ 

_____________________________________________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________ 

Conversion Factors and Vertical Datum 

Multiply By To obtain 

inch (in.) 2.54 centimeter 

inch (in.) 25.4 millimeter 

foot (ft) 0.3048 meter 

mile (mi) 1.609 kilometer 

acre 4,047 square meter 

acre 0.004047 square kilometer 

square mile (mi2

) 259 hectare 

square mile (mi2

) 2.59 square kilometer 

cubic foot per second (ft

3/s) 0.02832 cubic meter per second 

pound (lb) 0.4536 kilogram 

ton, short (2,000 lb) 907.2 kilogram 

Temperatures in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) by using the following equation: 

°

F = (°C x 1.8) + 32 

Vertical Datum: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929—a geodetic datum 

derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum 

of 1929. 

Chemical concentration in water is expressed in milligrams per liter (mg/L) or micrograms per liter (μg/L). 

vi 
Water Quality, Sediment Quality, and Stream-Channel 

Classification of Rock Creek, Washington, D.C., 1999-2000 

By Anita L. Anderson, Cherie V. Miller, Lisa D. Olsen, Edward J. Doheny, and Daniel J. Phelan 

Abstract 

Rock Creek Park is within the National Capital 

Region in Washington, D.C., and is maintained by 

the National Park Service. Part of Montgomery 

County, Maryland, and part of the District of 

Columbia drain into Rock Creek, which is a tributary of the Potomac River. Water quality in Rock 

Creek is important to biotic life in and near the 

creek, and in the Potomac River Basin and the 

Chesapeake Bay. The water quality of the Rock 

Creek Basin has been affected by continued urban 

and agricultural growth and development. The 

U.S. Geological Survey, in cooperation with the 

National Park Service, investigated water quality 

and sediment quality in Rock Creek over a 2-year 

period (1998–2000), and performed a streamchannel classification to determine the distribution 

of bottom sediment in Rock Creek. 

This report presents and evaluates water 

quality and bottom sediment in Rock Creek for 

water years 1999 (October 1, 1998 to 

September 30, 1999) and 2000 (October 1, 1999 to 

September 30, 2000). A synoptic surface-water 

assessment was conducted at five stations from 

June 23 to June 25, 1999, a temporal surface-water 

assessment was conducted at one station from 

February 18, 1999 to September 26, 2000, and 

bed-sediment samples were collected and assessed from three stations from August 17 to 

August 19, 1999. The synoptic surface-water 

assessment included pesticides (parent compounds 

and selected transformation products), field 

parameters, nutrients, and major ions. The temporal surface-water assessment included pesticides 

(parent compounds and selected transformation 

products) and field parameters. The bed-sediment 

assessment included trace elements and organic 

compounds (including low- and high-molecular 

weight polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides, and phthalates). Some, but not all, of the pesticides known 

to be used in the area were included in the synoptic 

water-quality assessment, the temporal waterquality assessment, and the bed-sediment assessment. In addition to the water-quality and sediment-quality assessments, a Rosgen streamchannel classification was performed on a 900­

foot-long segment of Rock Creek. 

In the synoptic water-quality assessment, two 

pesticides were found to be above published criteria for the protection of aquatic life. In the temporal water-quality assessment, four pesticides were 

found to be above criteria for the protection of 

aquatic life. In the bed-sediment assessment, 8 

trace elements, 12 polycyclic aromatic hydrocarbons, 6 pesticides or transformation products, 1 

phthalate compound, and total polychlorinated 

biphenyls were found to be above criteria for the 

protection of aquatic life. In the Rosgen classification, a comparison to a previous classification 

for this segment showed an increase in sands and 

other fine-grained sediments in the creek bed. 

Abstract 1 
Introduction 

Rock Creek Park is an urban park maintained by the 

National Park Service (NPS) and is located within the 

National Capital Region, Washington, D.C. (fig. 1). Rock 

Creek Park is approximately 9.3 mi (miles) long and up to 

1 mi wide, and comprises 1,754 acres at the lower end of the 

Rock Creek Basin, which is a subbasin of the Potomac River. 

The total length of Rock Creek (in Maryland and 

Washington, D.C.) is approximately 33 mi of meandering 

stream (fig. 1). The creek flows from its source near 

Laytonsville, Maryland to the Potomac River in Washington, 

D.C. Approximately 60 mi2 (square miles) of its drainage 

basin are in Montgomery County, Maryland, and 16 mi

2 are 

in Washington, D.C. Rock Creek Park extends from the 

Maryland–Washington D.C. boundary downstream to the 

confluence of Rock Creek and the Potomac River. 

Two park areas, Rock Creek Park and the Rock Creek 

and Potomac Parkway, make up the study area. U.S. 

Geological Survey (USGS) sampling station number 

01648998 is located near Q Street and the Rock Creek and 

Potomac Parkway. All other sampling stations are located 

in Rock Creek Park (fig. 2). In this report, the two park 

areas are referred to collectively as “Rock Creek Park.” 

Pesticides used on the Rock Creek Golf Course and in 

Rock Creek Park are controlled by NPS. Ongoing growth 

and development in the Washington, D.C. area have led to 

increased concentrations (above background levels) of 

nutrients, pesticides, and toxic and hazardous materials in 

streamwater and sediments (Donnelly and Ferrari, 1998). 

Intensive development in Montgomery County, Maryland 

has caused an increase in the use of pesticides, fertilizers, 

and other toxic and hazardous materials in the Rock Creek 

Basin (Maryland Department of Agriculture, 1993, 1996, 

1999). Although pesticides are beneficial for controlling 

unwanted organisms, they may adversely affect aquatic life 

and human health. Many pesticides are soluble in water and 

can enter surface-water bodies in dissolved form, either in 

storm runoff or through ground-water discharge. Some 

pesticides can bind to soil particles, which may be transported to surface-water bodies through soil erosion. Pesticides bound to soil particles can remain suspended in the 

water column, or become incorporated into bed sediment 

after settling. 

The U.S. Environmental Protection Agency (USEPA) 

has established criteria for the protection of aquatic life, but 

only for a limited list of contaminants (U.S. Environmental 

Protection Agency, 1999). Other sources of criteria for 

water quality and sediment quality include the Canadian 

water-quality and sediment-quality guidelines for the protection of aquatic life (Canadian Council of Ministers of the 

Environment, 1999), the Great LakesCriteria for the Protection of Aquatic Life (International Joint Commission United 

States and Canada, 1989), and Sediment Assessment Guidelines for Florida Coastal Waters (MacDonald, 1994). The 

USEPA has also established maximum contaminant levels 

(MCLs) for drinking water (U.S. Environmental Protection 

Agency, 2001). All of these criteria provide suggested 

threshold levels of selected contaminants, which are the lowest levels where probable effects to aquatic life and human 

health may occur, and chronic levels, for which effects are 

less likely but may occur over longer time scales (after years 

of exposure). Water-quality and sediment-quality data 

assessed in this study were compared to established guidelines, including drinking-water standards, even though 

Rock Creek is not used as a source of drinking water. 

Purpose and Scope 

The purpose of this report is to provide baseline 

water-quality data needed by park managers to plan 

protection strategies for Rock Creek Park. A synoptic 

surface-water assessment was conducted from 

June 23, 1999 to June 25, 1999, a temporal surface-water 

assessment was conducted from February 18, 1999 to 

September 26, 2000, and bed-sediment samples were 

collected from August 17, 1999 to August 19, 1999. The 

synoptic surface-water assessment included pesticides 

(parent compounds and selected transformation products), 

field parameters, nutrients, and major ions. The temporal 

surface-water assessment included pesticides (parent compounds and selected transformation products) and field 

parameters. The bed-sediment assessment included trace 

elements and organic compounds, including low- and highmolecular-weight polycyclic aromatic hydrocarbons (PAHs), 

total polychlorinated biphenyls (PCBs), pesticides (parent 

compounds and selected transformation products), and 

phthalates. Some, but not all, of the pesticides known to be 

used in the area were included in the synoptic water-quality 

assessment, the temporal water-quality assessment, and the 

bed-sediment assessment. In addition to the water-quality 

and sediment-quality assessments, a Rosgen stream classification was performed on a 900-ft (foot) segment of Rock 

Creek (fig. 2). 

Samples analyzed in this report were collected from 

seven locations along Rock Creek. Synoptic water-quality 

samples were collected from five locations to determine the 

baseline water quality of the creek. Temporal water-quality 

samples were collected 16 times from a single location over 

a period of 20 months (during water years 1999 and 2000) A, 

and included base-flow and stormflow samples. Bed-sediment samples were collected from three locations along 

Rock Creek to determine the accumulation of trace elements 

and organic compounds in the creek bed. Sample-collection 

dates, station identification numbers, and sampling locations 

are shown in table 1. 

A. A water year is defined as October 1 to September 30 of any given year. 

2 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Introduction 3 
4 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 1. Sample-collection dates, station identification numbers, and locations for synoptic 

water-quality, temporal water-quality, and bed-sediment samples collected from 

Rock Creek, Washington, D.C., during water years 1999 and 2000 

[ ° ' " , degrees, minutes, seconds] 

U.S. Geological 

Station Survey 

Date Location identification Latitude Longitude laboratory Sample 

number ( ° ' " ) ( ° ' " ) schedule type 

Synoptic water-quality samples 

06/23/1999 below West Beach Drive 01647998 38 58 58 077 02 24 2001, 2050, pesticides, nutrients, 

2701, 2702 major ions 

06/24/1999 Pinehurst Branch at 01648004 38 58 34 077 03 07 2001, 2050, pesticides, nutrients, 

Oregon Avenue 2701, 2702 major ions 

06/24/1999 Rock Creek tributary 01648006 38 58 00 077 02 46 2001, 2050, pesticides, nutrients, 

at Golf Course 2701, 2702 major ions 

06/25/1999 Joyce Road 01648010 38 51 36 077 02 31 2001, 2050, pesticides, nutrients, 

2701, 2702 major ions 

06/23/1999 Q Street 01648998 38 54 41 077 03 07 2001, 2050, pesticides, nutrients, 

2701, 2702 major ions 

Water Year 1999 temporal water-quality samples 

02/18/1999 Joyce Road - winter flood 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

03/09/1999 Joyce Road - winter base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

05/04/1999 Joyce Road - spring base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

05/23/1999 Joyce Road - spring flood 1 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

05/24/1999 Joyce Road - spring flood 2 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

05/24/1999 Joyce Road - spring flood 3 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

07/14/1999 Joyce Road - summer base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

Water Year 2000 temporal water-quality samples 

10/13/1999 Joyce Road - fall base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

01/10/2000 Joyce Road - winter storm 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

02/09/2000 Joyce Road - winter base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

03/21/2000 Joyce Road - spring storm 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

05/16/2000 Joyce Road - spring base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

06/22/2000 Joyce Road - summer storm 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

07/26/2000 Joyce Road - summer storm 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

09/11/2000 Joyce Road - fall base flow 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

09/26/2000 Joyce Road - fall storm 01648010 38 51 36 077 02 31 2001, 2050 pesticides 

Bed-sediment samples 

08/19/1999 Portal Branch 01647997 38 59 22 077 02 33 2400, 2500 trace elements, 

organics 

08/18/1999 Sherrill Drive 01648000 38 58 21 077 02 25 2400, 2500 trace elements, 

organics 

08/17/1999 Q Street 01648998 38 54 41 077 03 07 2400, 2500 trace elements, 

organics 

Introduction 5 
Previous Investigations 

An early report on water quality in Rock Creek (Sherman 

and Horner, 1935) documented progressive contamination in 

Rock Creek from the Maryland boundary to the mouth of the 

Potomac River. Many of Sherman and Horner’s recommendations were implemented in later years, and stream 

conditions seemed to be improving (CH2M Hill, 1979). A 

1966 investigation by the Federal Water Pollution Control 

Administration described the water quality of Rock Creek 

and the effects of waste outfalls in Montgomery County, 

Maryland and Washington, D.C., and showed high counts of 

total coliforms, fecal coliforms, and fecal streptococci in the 

lower Rock Creek drainage basin (CH2M Hill, 1979).

 The effects of urbanization on streamflow and sediment 

transport in the Rock Creek and Anacostia River Basins of 

Montgomery County from 1962 to 1974 were described by 

Yorke and Herb (1978). They reported large amounts of 

suspended sediment transported from construction sites, and 

evaluated the effectiveness of sediment-control practices in 

areas undergoing development. At the time, average annual 

yields of suspended sediment calculated for construction 

sites ranged from 7 to 100 tons per acre. 

A stormwater and water-quality management study 

by CH2M Hill (1977) described streams in Montgomery 

County that failed to meet Maryland water-quality criteria 

for water-contact recreation and aquatic life for each major 

branch or tributary to Rock Creek. An extensive basin conservation study by CH2M Hill (1979) described the flood 

hydrology, erosion and flood-control strategies, and plans for 

water-quality assessment and management within the 

Rock Creek Basin. 

From 1992 to 1996, the USGS performed a basin-wide 

assessment of the occurrence of pesticides in surface waters 

in the Potomac River Basin (Ator and others, 1998) as part 

of the National Water-Quality Assessment (NAWQA) 

program. This study determined that the concentrations of 

pesticides and nutrients in streams of the Potomac River 

Basin were among the highest in the Nation at various sites, 

and were generally related to agricultural or urban/suburban 

land use in the contributing basins. However, the concentrations of pesticides in streams and ground water of the 

Potomac River Basin measured during the NAWQA assessment were generally not threatening to human health or most 

ecosystems, based on 1998 standards. Stream habitat and 

fish communities were found to be most degraded in streams 

draining intensively agricultural or urban/suburban areas 

(Ator and others, 1998). Although the Rock Creek Basin is 

within the Potomac River Basin, none of the sites studied 

during the 1998 NAWQA assessment were within the 

Rock Creek Basin. 

In 1999, ground- and surface-water samples were collected in the upper Rock Creek Basin of Montgomery 

County and described by Duigon and others (2000). The 

effect of ground water on nitrate loads to streams was described, and nitrate concentrations were appreciably higher 

in ground-water samples in which atrazine was present at 

concentrations greater than 0.1 μg/L (micrograms per liter) 

(Duigon and others, 2000). 

The Montgomery County Department of Environmental 

Protection (DEP) Streams and Basin Program evaluated the 

general health of county waters and biological habitat in 

1996, and determined that each major branch or tributary 

to Rock Creek in Montgomery County failed to meet 

Maryland water-quality criteria (Montgomery County 

Department of Environmental Protection, 1997). The lower 

Rock Creek drainage basin drains directly into the Rock 

Creek study area, and includes four sub-basins. The Lower 

Mainstem East-West Highway sub-basin had a preliminary 

sub-basin/stream condition of “fair,” the Donnybrook 

Tributary had a preliminary sub-basin/stream condition of 

“poor,” the Coquelin Run had a preliminary sub-basin/ 

stream condition of “fair,” and the Lower Mainstem had a 

sub-basin/stream condition of “poor” (Montgomery County 

Department of Environmental Protection, 1997). The 

Lower Mainstem and Donnybrook Tributary had been 

assigned “poor” stream conditions because of excessive 

scouring, bank stability problems, and excessive sediment 

deposition (Montgomery County Department of Environmental Protection, 1997). 

Many programs are currently (2002) underway in 

Montgomery County to analyze and improve water quality. 

These include a basin restoration feasibility study by DEP, 

a similar study by the city of Rockville, and a restoration 

effort by the National Naval Medical Center to restore 

Stoney Creek, which is a tributary to Rock Creek that flows 

through the Federal property where the medical center is 

located (Montgomery County Department of Environmental 

Protection, 1997). 

After progressive contamination of Rock Creek from the 

Maryland boundary to the mouth of the Potomac River was 

reported in 1935, conditions were believed to have improved 

(Aalto and others, 1969; Maryland Department of Agriculture, 1993). Some studies (Yorke and Herb, 1978; CH2M 

Hill, 1979) showed that water-quality and sedimentation 

problems remained, however, and additional studies to 

assess the water quality in Rock Creek have since been 

conducted. 

Current Investigation 

The USGS began a study, in cooperation with NPS, to 

determine the water and sediment quality of Rock Creek in 

February 1999. Synoptic water-quality, temporal waterquality, and bed-sediment samples were collected from 

February 1999 through September 2000. Quality-control 

samples were also collected to evaluate the quality of sampling methods. Constituents analyzed for the study included 

PAHs, PCBs, pesticides, phthalates, and trace elements. 

On May 18, 2000, a fish-kill event occurred in 

Rock Creek that was under investigation by USEPA as of 

August 2000. Data from subsequent USEPA water-quality 

sampling were being analyzed and investigated to determine 

the cause of this event. A surface-water sample was collected by USGS on May 16, 2000 from station 01648010 

(fig. 2). Based on the data from this sample, the pesticides 

6 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
analyzed during this study are not believed to have caused 

the fish kill. 

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 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 and adjacent lands comprise the 

Chesapeake and Ohio Canal National Historic Park, 

which extends 184 mi upstream from its confluence with 

Rock Creek northward to Cumberland, Maryland, paralleling the Potomac River. The C&O Canal drains a small part 

of southern Montgomery County, which is not within the 

Rock Creek Basin, so the Rock Creek Basin effectively ends 

at the C&O Canal, rather than at the Potomac River. 

The Rock Creek Basin drains approximately 76.5 mi2, of 

which 15.9 mi2 are within Washington, D.C., south of the 

Maryland–Washington, D.C. boundary. North of the 

Maryland–Washington, D.C. boundary, there are approximately 60.6 mi2 of drainage in Montgomery County that 

serve as the headwaters of Rock Creek. NPS manages 1,754 

acres (2.74 mi2) or about 17 percent of all the land within the 

Rock Creek Basin in Washington, D.C. (CH2M Hill, 1979). 

The strongest regional effects on water quality in Rock 

Creek are believed to be the increase in urban development 

along with the increase in stormwater runoff over the 

impervious surfaces in the basin. 

Geology The Rock Creek Basin lies almost entirely 

within the upland section of the Piedmont Physiographic 

Province. The rocks underlying the basin are metamorphosed sedimentary and igneous rocks of Cambrian to 

Ordovician age that have been intensely folded, deformed, 

and recrystallized, 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). 

Bedrock in most areas of the Piedmont is covered by a 

mantle of regolith, rock debris, transported sediments, and 

soil (Darton, 1950), which generally has high intergranular 

porosity (Duigon and others, 2000). Permeability of the 

saprolite is variable, but commonly greatest just above the 

unweathered bedrock (Nutter and Otton, 1969). 

There are a few locations in the higher elevations of 

the basin where there are remnants of the Cretaceous 

Coastal Plain deposits, which are made up of unconsolidated 

gravels, sands, silts, and clays. Unconsolidated alluvium 

deposits of Holocene age, comprising gravel, sand, silt, and 

clay, are located along the stream channel. The thickness of 

these Holocene deposits varies by 5–10 ft throughout the 

study area (Fleming and others, 1994). The alluvial plain 

may also include recent flood deposits. 

Hydrology The hydrology of the Rock Creek Basin is 

affected by natural processes and anthropogenic activities. 

Precipitation causes direct runoff to the creek or infiltrates 

the ground to recharge the water table. About two-thirds of 

the water that falls as precipitation in the Piedmont region of 

central Maryland is returned to the atmosphere directly by 

evaporation or is taken up and transpired by plants (Dine and 

others, 1995). In the Rock Creek Basin, the large increases 

in impervious land surface have likely increased the amount 

of rainfall runoff, thereby decreasing the amount of rainfall 

that reaches the water table, thus decreasing evapotranspiration and ground-water recharge. Ground water flows 

through the fractures in the bedrock and through the overburden sediments to discharge directly to Rock Creek and 

nearby springs, where the water table intersects the land 

surface. Ground-water discharge maintains the base flow in 

the creek when there is no precipitation. 

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

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

which withdraws from the Potomac River near the western 

boundary of Washington, D.C. Many of the urban and 

suburban areas of Montgomery County in the Rock Creek 

Basin are supplied with drinking water by the Washington 

Suburban Sanitary Commission (WSSC), which also withdraws from the Potomac River. No major water suppliers in 

the Rock Creek Basin withdraw ground water for public use; 

however, private residences and small businesses in some of 

the northern and more rural reaches of the basin use wells for 

water supply and agriculture. There are no discharges of 

treated wastewater to the Rock Creek Basin in either 

Montgomery County, Maryland or Washington, D.C. Most 

water that enters the basin through the public water-supply 

system also leaves the basin by way of the WSSC wastewater treatment system (Judy Wheeler, U.S. Geological 

Survey, oral commun., 2000). 

There are two flood-control reservoirs within the entire 

Rock Creek drainage basin. Lake Needwood on Rock 

Creek and Lake Bernard Frank on North Branch Rock Creek 

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 outside the study area in 

Montgomery County, Maryland. 

Precipitation Annual precipitation, as measured by the 

National Oceanic and Atmospheric Administration at 

Dalecarlia Reservoir in Washington, D.C., is usually lowest 

in the spring to early summer and highest in late summer 

and fall. The total precipitation values for selected months 

in 1999 were: 1.56 in. (inches) for May, 2.54 in. for June, 

0.81 in. for July, 4.54 in. for August, and 11.05 in. for 

September. The total precipitation values for selected 

months in 2000 were: 2.04 in. for May, 5.04 in. for June, no 

data collected for July, 5.5 in. for August, and 4.62 in. for 

September (National Oceanic and Atmospheric Administration, 1999, 2000). These are months when pesticides are 

typically applied in this area. A few intense rainfall events 

occurred during the spring and fall of water year 1999; 

however, most of the year was characterized by intermittent 

Introduction 7 
Table 2. Land-use statistics for the Rock Creek Basin in the Washington, D.C. area, and the

 entire Rock Creek Basin in Washington, D.C. and Montgomery County, Maryland 

[From the USGS 30-minute resolution land-use data set, Vogelmann and others, 2001] 

Washington, D.C. area Entire Rock Creek Basin 

Land-use type square miles percent total area square miles percent total area 

Open Water/Wetlands 

Open water 0.0 0.0 0.3 0.4 

Woody wetlands 0.0 0.1 0.8 1.1 

Emergent herbaceous wetlands 0.0 0.1 0.2 0.3 

Subtotal 0.0 0.2 1.4 1.8 

Urban/Suburban 

Low intensity residential 6.6 41.9 27.5 36.0 

High intensity residential 1.8 11.3 1.9 2.4 

Commercial/industrial/transportation 1.2 7.7 5.4 7.1 

Subtotal 9.7 61.0 34.8 45.5 

Forest/Grassland 

Transitional 0.0 0.0 0.2 0.3 

Deciduous/evergreen forest 4.2 26.4 18.7 24.4 

Mixed forest 1.3 8.4 5.4 7.0 

Subtotal 5.5 34.8 24.2 31.6 

Agricultural 

Pasture/hay 0.0 0.0 10.1 13.2 

Row crops 0.0 0.0 2.0 2.6 

Urban recreational grasses 0.6 4.1 4.0 5.2 

Subtotal 0.6 4.1 16.1 21.0 

Total area 1 15.9 100.0 76.5 100.0 

1 Totals may not equal the sum of the individual land uses due to rounding. 

rainfall events of less intensity. During water year 2000, 

rain fell on an intermittent basis throughout the year, with no 

intense episodes similar to those in water year 1999. Rainfall amounts measured at Dalecarlia Reservoir near the Rock 

Creek study area during water years 1999 and 2000 are 

shown in figure 3. 

Land-Use Patterns Rock Creek Park is predominantly 

surrounded by urban and suburban areas in the lower basin 

of Rock Creek. The only open land of any appreciable 

extent consists of parkland, recreational areas, cemeteries, or 

institutional grounds (CH2M Hill, 1979). In this report, 

only four classes of land use are delineated. “Open water/ 

wetlands” includes all fluvial and lacustrine environments. 

“Urban/suburban” includes all businesses, residential 

neighborhoods, and other developed property. “Forest/ 

grassland” includes all woodlands, fields, and other natural 

habitats. “Agricultural” includes pastures, row crops, and 

open grassy areas. 

The USGS 30-minute resolution land-use data set 

(Vogelmann and others, 2001) shows that the lower part of 

the basin (about 16 mi

2, south of the Maryland–Washington, 

D.C. boundary) is approximately 4 percent agricultural, 35 

percent forest/grassland, and 61 percent urban/suburban 

(table 2). The entire Rock Creek Basin is approximately 21 

percent agricultural, 32 percent forest/grassland, and 46 percent urban/suburban (table 2). Urban/suburban development 

and agricultural land uses cover most of the area in the entire 

Rock Creek Basin. The distribution of land-use types in the 

entire Rock Creek Basin is shown in figure 4. The data for 

table 2 and figure 4 were derived from the National Land 

Cover Data set, which was compiled from Landsat satellite 

thermatic mapping (TM) imagery (collected in 1992), with a 

spatial resolution of 30 meters and supplemented by various 

ancillary data (Vogelmann and others, 2001). 

8 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Sources of Fertilizers and Pesticides to Rock Creek Park 

Numerous factors may affect differences in pesticide 

occurrence and concentrations in Rock Creek. Pesticide use 

for agricultural purposes is quantified in 3-year intervals at 

the County level by the Maryland Department of Agriculture 

(table 3), but data are limited for residential and general use 

by the public. Unregulated pesticide use, such as by consumer households, is largely undocumented. There are also 

differences between agricultural and urban/suburban land 

uses in the types and patterns of pesticides applied. Another 

factor that may affect the occurrence of pesticides in the 

Rock Creek Basin is the location and timing of precipitation. 

The high amount of paved land in urban/suburban areas may 

increase the chance of runoff during high rainfall or periods 

of extended irrigation. 

Rock Creek Park is surrounded by many private homes 

as well as some small businesses. Pesticide yield is likely to 

be highest in urban/suburban areas of moderate population 

density, where lots have relatively large proportions of turf 

grass and gardens, and pest control may be used (Hoffman 

and others, 2000). Areas farther north of the Maryland– 

Washington, D.C. boundary have a higher proportion of 

agricultural land use than urban/suburban land use. Agricultural areas generally have lower population densities and 

a smaller proportion of paved surfaces when compared to 

urban/suburban areas. Pesticide and fertilizer usage for 

agricultural areas with row crops can be high compared to 

nonagricultural areas; however, urban areas have also been 

shown to be appreciable sources of some pesticides (Larson 

and others, 1997). 

Potential Sources Outside the Park In the northern third 

of the Rock Creek Basin, the area surrounding Rock Creek 

is predominantly agricultural. Pesticides are applied to agricultural fields in many different ways, including aerial spraying, near-ground spraying, direct application to plants, and 

soil incorporation, to control insects and unwanted plants. 

Most agricultural pesticides are applied when they can have 

the greatest desired effect. Herbicides are usually applied 

just before planting to kill off old vegetation and a few 

weeks after the crop begins to sprout to target emerging 

weeds. Insecticides are generally applied at specific times, 

targeting specific insects at critical points in their life cycles 

(Larson and others, 1997). 

Organochlorine compounds, such as chlordane and 

1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and 

other pesticides have been used in the past to control pests. 

Since restrictions on organochlorine pesticides went into 

effect during the 1970s (such as the ban on DDT), organophosphate pesticide usage has increased. The compounds in 

use today vary according to their chemical structure, rate 

Introduction 9 
10 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 3. Estimated usage of selected pesticides in agricultural applications in 

Montgomery County, Maryland, 1994 and 1997—Continued 

Table 3. Estimated usage of selected pesticides in

Montgomery County,

 agricultural applications in 

Maryland, 1994 and 1997

 [Estimates are based on reports of combined pesticide usage by farm operators, certified private restricted-use pesticide applicators,

commercially licensed and public agencies, and non-licensed, non-farm segments of the population (Maryland Department of Agriculture,

1996 and 1999). This usage does not include residential and other non-documented usage; –, usage unknown or undocumented] 

Pounds of active 

ingredients per year 

Pesticide by agriculture Chemical class Common usage 

1994 1997 

2,4,5–T 1 – – Herbicide General weed control 

2,4–D 2 12,953 28,387 Chlorinated phenoxy Agriculture and turfgrass 

herbicide (hormone type) 

2,4–DB 3 5 – Hormone-type herbicide Alfalfa and soybeans 

Acetochlor 332 – Chloracetamide herbicide Vegetables and vineyards 

Acifluorfen 31 – Herbicide Soybeans, peanuts, and rice 

Alachlor 15,747 1,967 Acetanilide herbicide Corn, drybeans, peanuts, soybeans 

Aldicarb – – Carbamate insecticide, Agriculture 

acaricide, and nematicide 

Aldrin – – Insecticide Discontinued usage 

Atrazine 16,182 13,365 Triazine herbicide Corn, turfgrass, and some 

residential use 

Azinphos–methyl 29 107 Organophosphorus insecticide Fruits, vegetables, and ornamentals 

Benfluralin – – Dinitroaniline herbicide Agriculture and turfgrass 

Bentazon 250 – Herbicide Vegetables, lawns, soybeans, and corn 

Bromacil – 22 Uracil herbicide Weed/brush control, non-crop 

Bromoxynil – – Herbicide Weed control 

Butylate 86 – Herbicide Corn 

Carbaryl 1,229 4,145 Carbamate insecticide Agriculture and ornamentals 

Carbofuran 2,430 1,248 Carbamate insecticide, Systemic broad spectrum 

nematicide 

Chlordane – – Insecticide Discontinued usage 

Chlorothalonil 5,228 9,529 Fungicide Vegetables, turf, and ornamentals 

Chlorpyrifos 54,468 5,257 Insecticide Agriculture and residential (pets) 

Clopyralid 305 299 Post-emergent herbicide Crops, pasture, and rangeland 

Copper and copper salts 329,667 4,132 Fungicide, bactericide Vegetables 

Cyanazine 2,399 – Triazine herbicide Cotton and corn 

Dacthal – – Herbicide Lawns (to kill crabgrass) 

Diazinon 1,747 739 Phosphorothioate insecticide, Fruits, vegetables, and ornamentals 

nematicide 

Dicamba 1,421 3,332 Benzoic acid herbicide Crops and right-of-ways 

Dichlobenil 72 10 Benzonitrile herbicide Orchards, vineyards, ornamentals,

 and right-of-ways 

Dichlorprop – – Herbicide Aquatic weeds, rangeland, and 

right-of-ways 

Dieldrin – – Insecticide Discontinued usage 

Dinoseb – – Dinitrophenol herbicide Fruit trees 

1. 2,4,5–Trichlorophenoxyacetic acid. 

2. (2,4–Dichlorophenoxy)acetic acid. 

3. 4–(2,4–Dichlorophenoxy)butyric acid.

Introduction 11 
Table 3. Estimated usage of selected pesticides in agricultural applications in 

Montgomery County, Maryland, 1994 and 1997—Continued 

Pounds of active 

ingredients per year 

Pesticide by agriculture Chemical class Common usage 

1994 1997 

Disulfoton – – Organophosphate insecticide, Systemic control for vegetables

 acaricide and ornamentals 

Diuron 1,006 82 Substituted urea herbicide Cotton, orchards, vineyards,

 ornamentals, and gardens 

DDT 4 – – Insecticide Discontinued usage 

DNOC 5 – – Insecticide, fungicide, Apples and peaches 

herbicide, and defoliant 

Endosulfan 83 6 Insecticide and acaricide Fruits, vegetables, and ornamentals 

Endrin – – Organochlorine insecticide Discontinued usage 

EPTC 6 – – Herbicide Vegetables 

Ethalfluralin 60 80 Dinitroaniline herbicide Soybeans and vegetables 

Ethoprop – – Organophosphate insecticide, Vegetables and turf 

 nematicide 

Fenuron – – Herbicide Woody plants 

Fonofos – – Insecticide Soil pests 

Glyphosphate – 15,192 Non-selective postemergent Weed control and right-of-ways 

herbicide 

Heptachlor – – Insecticide Discontinued usage 

Lindane (γ–HCH) 7 3 2 Organochlorine insecticide Tobacco, fruits, and domestic usage 

Linuron 1,036 650 Substituted urea herbicide Agriculture 

MCPA 8 14 821 Phenoxy herbicide Small grains and turf 

(hormone type) 

MCPB 9 – – Herbicide Weed control 

Malathion 200 139 Organophosphate insecticide Fruits, vegetables, and ornamentals 

(and pet dip) 

Methiocarb – 82 Carbamate insecticide Home gardens 

ascaricide, and molluscicide 

Methomyl 122 28 Insecticide Vegetables, ornamentals, and fly 

control at feedlots 

Methoxychlor – 10 Diphenyl chloride insecticide Residential use to control houseflies,

 black flies, and mosquitoes 

Methyl azinphos – – Organophosphate insecticide Fruits, ornamentals, and shade trees 

Methyl parathion – – Organophosphate insecticide Cotton, corn, alfalfa, and soybeans 

Metolachlor 13,522 7,930 Chloracetanilide Corn and soybeans 

Metribuzin 58 124 Triazinone herbicide Rowcrops

 4. 1,1,1–Trichloro–2,2–bis(p–chlorophenyl)ethane and 1,1,1,–trichloro–2,2–bis(o–chlorphenyl)ethane.

 5. 4,6–Dinitro–o–cresol.

 6. s–Ethyl dipropylthiocarbamate.

 7. Lindane is a technical mixture consisting primarily of γ–HCH (γ–1,2,3,4,5,6–hexachlorocyclohexane).

 8. 4–(4–Chloro–2–methylphenoxy) acetic acid.

 9. 4–(4–Chloro–2–methylphenoxy) butanoic acid. 

12 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 3. Estimated usage of selected pesticides in agricultural applications in 

Montgomery County, Maryland, 1994 and 1997—Continued 

Pesticide 

Pounds of active 

ingredients per year 

by agriculture 

1994 1997 

Chemical class Common usage 

Molinate 

Napropamide 

Neburon 

Norflurazon 

Oryzalin 

– 

– 

– 

– 

389 

– 

– 

– 

– 

867 

Herbicide 

Herbicide 

Herbicide 

Herbicide 

Dinitroaniline herbicide 

Agriculture 

Orchards, vineyards, vegetables, 

and ornamentals 

Agriculture 

Agriculture 

Fruit trees, vineyards, turf, and 

ornamentals 

Oxamyl 

Parathion 

Pebulate 

Pendimethalin 

Permethrin 

10 

6 

– 

19,997 

27,832 

1 

17 

– 

12,521 

4,280 

Carbamate insecticide,

 nematicide, and acaricide 

Organophosphate insecticide 

Herbicide 

Dinitroaniline herbicide 

Pyrethroid insecticide 

Agriculture and ornamentals 

Agriculture 

Agriculture 

Cotton, vegetables, ornamentals, 

and industrial grounds maintenance 

Orchards, vineyards, ornamentals, 

and livestock 

Phorate 

Pichloram 

Prometon 

Pronamide 

Propachlor 

– 

– 

310 

– 

– 

– 

– 

958 

– 

– 

Insecticide 

Herbicide 

Non-selective herbicide 

Herbicide 

Herbicide 

Agriculture 

Right-of-ways (non-agricultural) 

Right-of-ways (non-agricultural) 

Agriculture and ornamentals 

Corn and grains 

Propanil 

Propargite 

Propham 

Propoxur 

Simazine 

1,042 

– 

– 

3 

3,915 

206 

– 

– 

741 

5,233 

Anilide herbicide 

Acaricide 

Herbicide 

Carbamate insecticide 

Triazine herbicide 

Rice 

Fruit trees and ornamentals 

Agriculture and turfgrass 

Fruits, vegetables, and ornamentals 

Lawns, fairways, aquatic control, corn,

 and vegetables 

Silvex 

Tebuthiuron 

Terbacil 

Terbufos 

Thiobencarb 

– 

33 

2 

– 

– 

– 

– 

7 

– 

– 

Herbicide 

Herbicide 

Herbicide 

Organophosphate insecticide

 and Nematicide 

Herbicide 

Agriculture and turf (for woody

 growth) 

Right-of-ways 

Fruits 

Corn 

Agriculture 

Triclopyr 

Trifluralin 

646 

1,074 

1,556 

2,201 

Systemic herbicide 

Dinitroaniline herbicide 

Turf and right-of-ways 

Corn, soybeans, and right-of ways 

Total pounds of pesticides 

applied for agriculture in 

Montgomery County 

(including others not in 

this list and not analyzed 

in this study). 

2,292,499 350,740 

Introduction 13 
of application, and transport potential, but are generally 

more soluble and shorter-lived than historically used pesticides (Larson and others, 1997; Maryland Department of 

Agriculture, 1996, 1999). A pesticide may be transported in 

dissolved form or bound to soil particles (Nowell and others, 

1999). Pesticides can then enter the atmosphere, vadose 

zone, aquifer, or a surface-water body (Nowell and others, 

1999). Pesticides generally move from fields to surfacewater bodies in runoff by either overland sheet-flow or in 

manmade or erosion-created drainage channels. Storm 

runoff can also cause erosion of previously contaminated 

soil, which can then be transported and redistributed downstream. All of these transport mechanisms may contribute 

to the degradation of water quality in Rock Creek. 

Potential Sources Within the Park Rock Creek Park 

houses a public 18-hole golf course that extends westward 

from 16th Street to Beach Drive, which runs adjacent to 

Rock Creek, and from Military Road northward to Sherrill 

Drive (fig. 2). This golf course is maintained entirely by 

NPS. The hilly terrain of the golf course can increase the 

potential for runoff during extended irrigation and rainfall 

events at the site near the golf course compared to the other 

sampling sites in this study. During water year 1999 

(October 1, 1998 to September 30, 1999) and water year 

2000 (October 1, 1999 to September 30, 2000), various 

insecticides and herbicides were applied to the Rock Creek 

Golf Course. Application dates of each of these pesticides 

along with areas of application are listed in table 4. 

Station number 01648006 is located on a tributary in a 

draw that drains the 14th, 15th, and 16th holes of the golf 

course. Runoff from this part of the golf course may be 

carried into Rock Creek through the tributary located in this 

draw. Each of the pesticides listed in table 4 were applied to 

the greens, tees, collars, and approaches of all 18 holes of the 

golf course, with the exception of an application of chlorothalonil on June 27, 1999. This application was made only 

on tees 1–7, 13, and 18. Therefore, this application would 

not have been transported directly into Rock Creek through 

this tributary. 

Pesticides were also applied by NPS on areas of the park 

outside the golf course where exotic (non-native) species of 

plants are known to exist. A detailed list of the pesticides 

applied by NPS in water years 1999 and 2000 and general 

areas of application is included in tables 5 and 6. The concentrations of the pesticides applied to the park by NPS vary 

according to the type of pesticide used. All concentrations 

were within recommended application criteria. 

Acknowledgments 

The authors wish to thank the following people and 

agencies for their important contributions to this study: 

Douglas Curtis of the National Park Service, National 

Capital Region, and William Yeaman of the National Park 

Service, Rock Creek Park, for collecting local park data and 

giving the authors a thorough overview of the field site. 

The authors also thank the following USGS colleagues: 

L. Joseph Bachman, David Brower, Janet Denis, Matthew 

Ferrari, Jeffrey Kvech, Brenda Majedi, Wendy McPherson, 

and Jeffrey Raffensperger for assisting with the collection 

of water-quality data during this study; Roger Starsoneck 

for his help in the Rosgen analysis field effort; and Michael 

Wieczorek for mapping the Rock Creek Basin and analyzing 

land-use distribution within the basin. Thanks also go to 

the Publications Section of the Maryland-Delaware-D.C. 

District of the USGS for their assistance in preparing this 

report: Timothy Auer for the maps and graphics, Donna 

Knight for layout, and Valerie Gaine for editorial review. 

The authors especially thank Martha Hayes for project 

management and overseeing sampling collection. 

14 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 4. 	Pesticides applied to Rock Creek Golf Course, Washington, D.C., during 

water years 1999 and 2000

 [Data on file at U.S. Geological Survey Office, Baltimore, Maryland. Cross-referenced with California Department of Pesticide

 Regulation in conjunction with U.S. Environmental Protection Agency (USEPA)] 

USEPA Application Active Area 

regulation number date ingredient applied 

Water Year 1999 

264-480 10/01/1998 Iprodione Greens 1-18 

707-245 05/03/1999 Dithiopyr Collars & approaches 

264-480 05/06/1999 Iprodione Greens 1-18 

50534-209 06/01/1999 Chlorothalonil Greens 1-18 

264-335 06/08/1999 Carbaryl Greens 1-18 

50534-209 06/22/1999 Chlorothalonil Greens 1-18 

100-741 06/22/1999 Propiconazole Greens 1-18 

50534-209 06/27/1999 Chlorothalonil Tees 1-7, 13, 18 

264-515 06/30/1999 Aluminum tris Greens 1-18 

707-87 06/30/1999 Mancozeb Greens 1-18 

50534-209 07/20/1999 Chlorothalonil Greens 1-18 

100-796 07/20/1999 Propionic acid Greens 1-18 

264-335 08/03/1999 Carbaryl Greens 1-18 

100-741 08/03/1999 Propiconazole Greens 1-18 

50534-209 08/24/1999 Chlorothalonil Greens 1-18 

Water Year 2000 

50534-209 12/09/1999 Chlorothalonil Greens 1-18 

1001-63 06/01/2000 Thiophanate methyl Greens 1-18 

264-335 06/02/2000 Carbaryl Greens 1-18 

707-87 06/23/2000 Mancozeb Greens 1-18 

707-87 07/06/2000 Mancozeb Tees 1-18 

10182-400 07/07/2000 λ-cyhalothrin Greens 1-18 

264-480 07/07/2000 Iprodione Tees 1-18 

50534-209 07/07/2000 Chlorothalonil Greens 1-18 

1001-63 07/31/2000 Thiophanate methyl Greens 1-18 

10182-400 07/31/2000 λ-cyhalothrin Greens 1-18 

707-87 08/02/2000 Mancozeb Greens 1-18 

50534-209 08/15/2000 Chlorothalonil Greens 1-18 

Introduction 15 
Table 5. Pesticides applied to Rock Creek Park, Washington, D.C., during water year 1999

 [Data on file at U.S. Geological Survey Office, Baltimore, Maryland. Cross-referenced with California Department

 of Pesticide Regulation in conjunction with U.S. Environmental Protection Agency (USEPA)]

USEPA 

regulation number 

Application 

date † 

Active 

ingredient 

Area 

applied 

62719-40 

62719-40 

62719-40 

62719-37 

62719-37 

01/21/1999 

01/26/1999 

02/05/1999 

02/11/1999 

02/16/1999 

Triclopyr 

Triclopyr 

Triclopyr 

Triclopyr 

Triclopyr 

Soapstone Valley Trail 

Soapstone Valley Trail 

Western Ridge Trail 

Pinehurst Branch 

Pinehurst Branch 

62719-37 

594-308 

594-308 

524-343 

62719-37 

02/19/1999 

03/01/1999 

03/02/1999 

03/02/1999 

03/05/1999 

Triclopyr 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Pinehurst Branch 

Nature Center meadow 

Black Horse Trail 

Black Horse Trail 

Pinehurst Branch 

62719-37 

594-308 

524-343 

62719-37 

594-308 

04/07/1999 

04/07/1999 

04/07/1999 

06/25/1999 

07/01/1999 

Triclopyr 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Boundary Bridge 

Boundary Bridge 

Boundary Bridge 

Beach Drive near Bringham Drive 

East Beach Drive at Kalmia Bridge 

594-308 

524-343 

594-308 

524-343 

594-308 

07/12/1999 

07/12/1999 

07/16/1999 

07/19/1999 

07/21/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

East Beach Drive 

East Beach Drive -Fenwick Branch 

East Beach Drive 

East Beach Drive 

East Beach Drive 

594-308 

524-343 

524-343 

524-343 

594-308 

07/23/1999 

07/23/1999 

07/27/1999 

07/29/1999 

07/29/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

East Beach Drive 

East Beach Drive near Redbud Drive 

East Beach Drive near Sycamore Street 

East Beach Drive near Portal Street 

East Beach Drive 

594-308 

594-308 

524-343 

62719-37 

594-308 

07/29/1999 

07/30/1999 

07/30/1999 

08/02/1999 

08/02/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

West Beach Drive 

West Beach Drive 

East Beach Drive - west bank 

Dumbarton Oaks Park 

West Beach Drive 

62719-37 

594-308 

62719-37 

594-308 

594-308 

08/03/1999 

08/03/1999 

08/04/1999 

08/04/1999 

08/05/1999 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Glyphosate 

Dumbarton Oaks Park 

West Beach Drive 

Dumbarton Oaks Park 

North Portal Drive 

Kudzu sites 

62719-40 

594-308 

594-308 

524-343 

62719-37 

594-308 

08/06/1999 

08/06/1999 

08/09/1999 

08/09/1999 

08/10/1999 

08/10/1999 

Triclopyr 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

South Portal Drive 

North Portal Drive 

North Portal Drive 

North Portal Bank of Fenwick Branch 

Dumbarton Oaks Park 

North Portal Drive - South Portal Drive 

† No data available from water year 1999 prior to January 1, 1999. 

16 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 5. Pesticides applied to Rock Creek Park, Washington, D.C., during water year 1999— 

Continued 

USEPA 

regulation number 

Application 

date † 

Active 

ingredient 

Area 

applied 

524-343 

594-308 

524-343 

594-308 

594-308 

62719-37 

08/10/1999 

08/11/1999 

08/11/1999 

08/12/1999 

08/12/1999 

08/13/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

North Portal Bank and South Portal Bank 

South Portal Drive 

South Portal Drive near East Beach Drive 

South Portal Drive 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

594-308 

524-343 

62719-37 

524-343 

62719-37 

594-308 

08/13/1999 

08/13/1999 

08/16/1999 

08/16/1999 

08/17/1999 

08/17/1999 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

South Portal Drive 

South Portal Drive 

Dumbarton Oaks Park 

Bingham Drive 

Dumbarton Oaks Park 

Riley Spring Bridge 

524-343 

594-308 

524-343 

594-308 

62719-40 

62719-37 

08/17/1999 

08/18/1999 

08/18/1999 

08/19/1999 

08/23/1999 

08/23/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Triclopyr 

Riley Spring Bridge 

Riley Spring Bridge 

Riley Spring Bridge 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Beach Drive along creek 

62719-37 

594-308 

594-308 

62719-40 

594-308 

594-308 

8/23/1999 

08/23/1999 

08/25/1999 

09/01/1999 

09/01/1999 

09/01/1999 

Triclopyr 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Glyphosate 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Bend in Creek near Hydro Dam 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Wise Road 

62719-40 

62719-37 

594-308 

524-343 

62719-37 

62719-37 

09/02/1999 

09/02/1999 

09/02/1999 

09/02/1999 

09/03/1999 

09/13/1999 

Triclopyr 

Triclopyr 

Glyphosate 

Glyphosate 

Triclopyr 

Triclopyr 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

West Beach Drive 

Riley Spring Bridge 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

594-308 

524-343 

524-343 

62719-40 

62719-37 

594-308 

09/13/1999 

09/13/1999 

09/13/1999 

09/14/1999 

09/14/1999 

09/14/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Triclopyr 

Glyphosate 

Wise Road 

Riley Spring Bridge - Fenwick Branch 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

West Beach Drive Bridge 

524-343 

594-308 

524-343 

62719-37 

524-343 

524-343 

09/14/1999 

09/20/1999 

09/20/1999 

09/23/1999 

09/23/1999 

09/23/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Glyphosate 

Riley Spring Bridge near West Beach Drive 

Beach Drive at Boundary Bridge 

Riley Spring Bridge along Beach Drive 

Dumbarton Oaks Park 

Boundary Bridge - west bank 

Rolling Meadow Bridge to mouth of Pinehurst 

524-343 

62719-37 

524-343 

09/23/1999 

09/24/1999 

09/24/1999 

Glyphosate 

Triclopyr 

Glyphosate 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Rolling Meadow Bridge to Sherrill Drive 

Introduction 17 
Table 6. Pesticides applied to Rock Creek Park, Washington, D.C., during water year 2000

 [Data on file at U.S. Geological Survey Office, Baltimore, Maryland. Cross-referenced with California Department of

 Pesticide Regulation in conjunction with U.S. Environmental Protection Agency (USEPA)] 

USEPA 

regulation number 

Application 

date 

Active 

ingredient 

Area 

applied 

524-343 

524-343 

524-343 

594-308 

524-343 

10/01/1999 

10/12/1999 

10/15/1999 

10/19/1999 

10/19/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Rolling Meadow Bridge to board walk 

Riley Spring Bridge and trail 

Riley Spring Bridge - Flood plain 

Riley Spring Bridge 

Riley Spring Bridge - Flood plain 

524-343 

524-343 

524-343 

524-343 

62719-37 

10/22/1999 

10/22/1999 

10/22/1999 

10/26/1999 

10/27/1999 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Riley Spring Bridge - Flood plain 

Maintenance Area - Flood plain 

Pinehurst Branch at West Beach Drive 

Pinehurst Branch at West Beach Drive 

Creek edge from Beach Drive to Boundary Bridge 

524-343 

62719-37 

524-343 

524-343 

524-343 

10/27/1999 

10/28/1999 

10/28/1999 

11/01/1999 

03/06/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Glyphosate 

Glyphosate 

Boundary Bridge and West Beach Drive 

Creek edge from Beach Drive to Boundary Bridge 

Boundary Bridge and West Beach Drive 

Boundary Bridge 

Ranunculus plots - Flood plain 

524-343 

524-343 

62719-40 

524-343 

524-343 

03/06/2000 

03/09/2000 

04/27/2000 

05/01/2000 

05/01/2000 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Glyphosate 

Boundary Bridge 

Pinehurst Branch 

Nature Center 

Boundary Bridge at West Beach Drive 

Boundary Bridge at West Beach Drive 

524-343 

524-343 

524-343 

62719-37 

624-343 

05/02/2000 

05/02/2000 

06/30/2000 

06/30/2000 

07/06/2000 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Wise Road 

Wise Road 

Rolling Meadow Bridge 

Rolling Meadow Bridge 

Rolling Meadow Bridge to Sherrill Drive 

62719-37 

524-343 

62719-37 

524-343 

62719-37 

07/06/2000 

07/07/2000 

07/07/2000 

07/10/2000 

07/10/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Rolling Meadow Bridge to Sherrill Drive 

Rock Creek near Sherrill Drive 

Rock Creek near Sherrill Drive 

Rock Creek near Sherrill Drive 

Rock Creek near Sherrill Drive 

524-343 

62719-37 

524-343 

62719-37 

62719-40 

07/13/2000 

07/13/2000 

07/14/2000 

07/14/2000 

07/18/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Triclopyr 

Rock Creek near Riley Spring Bridge 

Rock Creek near Riley Spring Bridge 

Rock Creek near Riley Spring Bridge 

Rock Creek near Riley Spring Bridge 

Melvin Hazen part of test plots 

524-343 

62719-37 

62719-40 

524-343 

62719-37 

07/18/2000 

07/18/2000 

07/21/2000 

08/04/2000 

08/04/2000 

Glyphosate 

Triclopyr 

Triclopyr 

Glyphosate 

Triclopyr 

Riley Spring Bridge near Beach Drive 

Riley Spring Bridge near Beach Drive 

Waterfront Park near harbor parking lot 

Riley Spring Bridge near creek and valley trail 

Riley Spring Bridge near creek and valley trail 

62719-37 

594-308 

62719-40 

08/04/2000 

08/04/2000 

08/08/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Riley Spring Bridge near Valley Trail 

Riley Spring Bridge near Valley Trail 

Sherrill Drive to Riley Spring Bridge 

18 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
[From Department of Interior, National Park Service, Pesticide use log. Cross-referenced with California Department of

 Pesticide Regulation in conjunction with U.S. Environmental Protection Agency (USEPA; –, no data available)]

Table 6. Pesticides applied to Rock Creek Park,Washington, D.C., during water year 2000—Continued 

USEPA 

regulation number 

Application 

date 

Active 

ingredient 

Area 

applied 

594-308 

62719-37 

524-343 

62719-37 

62719-40 

08/08/2000 

08/08/2000 

08/09/2000 

08/09/2000 

08/10/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Triclopyr 

Valley Trail near West Beach Drive 

Valley Trail near West Beach Drive 

Rock Creek Edge near Fenwick Bridge 

Rock Creek Edge near Fenwick Bridge 

Dumbarton Oaks Park 

594-308 

62719-37 

62719-40 

524-343 

62719-37 

08/14/2000 

08/14/2000 

08/15/2000 

08/15/2000 

08/15/2000 

Glyphosate 

Triclopyr 

Triclopyr 

Glyphosate 

Triclopyr 

Maintenance yard to Fenwick Bridge 

Fenwick Bridge near maintenance yard 

Fenwick Bridge near maintenance yard 

West Beach Drive near Fenwick Bridge 

West Beach Drive near Fenwick Bridge 

524-343 

62719-37 

594-308 

62719-37 

524-343 

08/17/2000 

08/17/2000 

08/17/2000 

08/17/2000 

08/21/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Fenwick Bridge - north bank 

Fenwick Bridge - north bank 

Fenwick Bridge near West Beach Drive 

Fenwick Bridge near West Beach Drive 

Rock Creek near Beach Bridge - flood plain 

62719-37 

594-308 

62719-37 

524-343 

62719-37 

08/21/2000 

08/21/2000 

08/21/2000 

08/22/2000 

08/22/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Rock Creek near Beach Bridge - flood plain 

Path, horse trail and interior flood plain 

Path, horse trail and interior flood plain 

Rock Creek near West Beach Bridge - flood plain 

Rock Creek near West Beach Bridge - flood plain 

594-308 

62719-37 

594-308 

62719-37 

594-308 

08/22/2000 

08/22/2000 

08/25/2000 

08/25/2000 

08/28/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Path, interior flood plain 

Path, interior flood plain 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Glover Road near Ross Drive 

594-308 

594-308 

594-308 

594-308 

62719-37 

08/30/2000 

08/31/2000 

09/05/2000 

09/06/2000 

09/06/2000 

Glyphosate 

Glyphosate 

Glyphosate 

Glyphosate 

Triclopyr 

Ross Drive 

Ross Drive 

Ross Drive 

Flood plain 

Flood plain 

594-308 

594-308 

62719-37 

594-308 

62719-37 

09/06/2000 

09/07/2000 

09/07/2000 

09/08/2000 

09/08/2000 

Glyphosate 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Beach Drive 

Bingham Drive to bike trail 

Bingham Drive to bike trail 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

594-308 

62719-37 

594-308 

62719-37 

524-343 

09/11/2000 

09/11/2000 

09/11/2000 

09/11/2000 

09/12/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Grant Road, Bingham Drive and Military Road 

Grant Road, Bingham Drive and Military Road 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Rock Creek to Beach Bridge - flood plain 

62719-37 

594-308 

62719-37 

09/12/2000 

09/12/2000 

09/12/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Rock Creek to Beach Bridge - flood plain 

Wise Road 

Wise Road 

Introduction 19 
[From Department of Interior, National Park Service, Pesticide use log. Cross-referenced with California Department of

 Pesticide Regulation in conjunction with U.S. Environmental Protection Agency (USEPA; –, no data available)]

Table 6. Pesticides applied to Rock Creek Park,Washington, D.C., during water year 2000—Continued 

USEPA 

regulation number 

Application 

date 

Active 

ingredient 

Area 

applied 

524-343 

62719-37 

594-308 

52719-37 

594-308 

09/13/2000 

09/13/2000 

09/13/2000 

09/13/2000 

09/14/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Flood plain (wet areas) 

Flood plain (wet areas) 

Flood plain 

Flood plain 

Dumbarton Oaks Park 

62719-37 

594-308 

62719-37 

594-308 

62719-37 

09/14/2000 

09/18/2000 

09/18/2000 

09/20/2000 

09/20/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Dumbarton Oaks Park 

Boundary Bridge - north end 

Boundary Bridge - north end 

Boundary Bridge - north end 

Boundary Bridge - north end 

594-308 

62719-37 

594-308 

62719-37 

524-343 

09/21/2000 

09/21/2000 

09/22/2000 

09/22/2000 

09/27/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Dumbarton Oaks Park 

Dumbarton Oaks Park 

Boundary Bridge near trail 

Boundary Bridge near trail 

Wise Road near West Beach Drive 

62719-37 

594-308 

62719-37 

524-343 

62719-37 

09/27/2000 

09/27/2000 

09/27/2000 

09/28/2000 

09/28/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Wise Road near West Beach Drive 

West Beach Drive near Riley Spring Bridge 

West Beach Drive near Riley Spring Bridge 

Wise Road near West Beach Drive 

Wise Road near West Beach Drive 

524-343 

62719-37 

594-308 

62719-37 

594-308 

09/28/2000 

09/28/2000 

09/28/2000 

09/28/2000 

09/28/2000 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Dumbarton Oaks near bridge and trail 

Dumbarton Oaks near bridge and trail 

Tree Island along Cart Trail 

Tree Island along Cart Trail 

West Beach Drive near Riley Spring Bridge 

62719-37 

524-343 

62719-37 

594-308 

62719-37 

09/28/2000 

09/29/2000 

09/29/2000 

09/29/2000 

09/29/2000 

Triclopyr 

Glyphosate 

Triclopyr 

Glyphosate 

Triclopyr 

West Beach Drive near Riley Spring Bridge 

Wise Road near West Beach Drive 

Wise Road near West Beach Drive 

West Beach Drive near Riley Spring Bridge 

West Beach Drive near Riley Spring Bridge 

20 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Methods of Investigation 

Streamflow rates, basic field parameters, and samples 

for analysis of pesticides, nutrients, and major ions were collected from seven sites in Rock Creek Park (fig. 2). Synoptic water-quality samples were collected from five sites 

(01647998, 01648004, 01648006, 01648010, and 01648998) 

and analyzed for pesticides (parent compounds and selected 

transformation products), field parameters, nutrients, and 

major ions, in accordance with USGS protocols (Wilde and 

others, 1998). Temporal water-quality samples were collected at station 01648010 and analyzed for pesticides 

(parent compounds and selected transformation products) 

and field parameters. Bed-sediment samples were collected 

from three sites (01647997, 01648000, and 01648998) and 

analyzed for trace elements (including metals) and organic 

compounds (including low- and high-molecular weight 

PAHs, PCBs, pesticides, and phthalates). Sampling dates 

and locations are listed and shown in table 1 and figure 2, 

respectively. 

Site Selection 

Sampling sites were selected after reviewing topographic maps and reviewing the drainage pattern unique to 

Rock Creek Park. Four stations were selected along the 

mainstem of Rock Creek to assess the water and sediment 

quality in the mainstem of the river. In downstream order, 

these stations are 01647998, 01648000, 01648010, and 

01648998. The downstream sampling site (01648998) was 

selected to determine the final concentration of selected 

analytes before Rock Creek merges with the Potomac River. 

Three stations (01647997, 01648004, and 01648006) on 

tributaries to Rock Creek were selected to target small drainage basins within Rock Creek Park, and to assess potential 

contaminant movement from the golf course and the surrounding neighborhoods. Station 01648006 targeted the 

small drainage basin that included the golf course (fig. 2). 

Sampling and Field Methods 

Surface-water samples (synoptic and temporal) were 

collected using equal-width integrated sampling techniques 

and composited in a cone splitter, a USGS device for collecting representative sub-samples from large volume 

samples. Samples for the analysis of nutrients in whole 

water were preserved with concentrated sulfuric acid. 

Samples for dissolved-phase constituents were filtered 

through a 0.45-μm (micrometer) polycarbonate capsule 

filter. Samples were shipped on ice overnight to the USGS 

National Water-Quality Laboratory (NWQL) in Denver, 

Colorado and refrigerated until analysis. Field measurements were taken concurrently with water-quality sample 

collection. Specific conductance, pH, dissolved oxygen, 

and temperature were determined with a calibrated YSI 

6600-0 multimeter following methods presented in Wilde 

and Radtke (1998). All sample-collection and qualityassurance methods used for surface-water sampling are 

documented in the USGS National Field Manual (Wilde and 

others, 1998). 

Bed sediment was collected at stations 01647997, 

01648000, and 01648998 using a scoop made of inert 

materials to skim the top centimeter of bed sediment from 

multiple deposition zones within the designated stream 

reach. Stream reaches for each station were approximately 

300 ft long. The samples from each station were composited into a glass jar and then transported on ice to the USGS 

laboratory for analysis. Samples were sieved in the field to 

remove coarse material. Samples for trace-element analyses 

were sieved through a 63-micron nylon filter, and samples 

for organic-compound analyses were sieved through a 2-mm 

(millimeter) stainless-steel sieve. All sample-collection 

techniques used for bed-sediment sampling are documented 

in Radtke (1998). 

Analytical Methods 

Nitrogen and phosphorus were analyzed by colorimetric 

methods using air-segmented continuous-flow analyzers B, 

operated with pecked sampling and bubble-gated detectors 

(Patton and Wade, 1997). Kjeldahl nitrogen (organic nitrogen plus ammonia) and total phosphorus were pre-digested 

batchwise (Patton and Truit, 1992; Fishman, 1993). All 

laboratory methods are documented and verified for bias, 

accuracy, and precision with standard-reference materials 

and participation in the USGS Office of Water Quality sample-testing program (Maloney and others, 1994; Pritt and 

Raese, 1995). 

Pesticides and pesticide transformation products in surface water were determined by two different analytical 

techniques. In one method, pesticides were extracted onto a 

C-18 solid-phase cartridge then eluted from the cartridge and 

analyzed by capillary-column Gas Chromatography-Mass 

Spectrometry (GC/MS) with selected-ion monitoring. 

Recoveries of surrogate compounds in thisstudy using the 

B. Alpkem Corporation, Clackamas, Oregon 

Methods of Investigation 21 
GC/MS method ranged from 70 to 120 percent. In the 

second method, samples were passed through a Carbopak–B 

solid-phase extraction cartridge followed by elution of the 

pesticides captured on the Carbopak–B and photodiodearray detection in conjunction with High-Performance Liquid Chromatography (HPLC). Base/neutral compounds 

were eluted separately from acid compounds. Recoveries of 

surrogate compounds in the HPLC method ranged from 56 

to 131 percent. More information on quality-assurance 

methods is available in Zaugg and others (1995) and Werner 

and others (1996). Pesticide concentrations presented in 

this report have not been corrected for analytical recovery. 

Organochlorine pesticides and PCBs in bed sediments 

were first isolated by Soxhlet extraction using dichloromethane. Compounds were then analyzed by dual-capillary-column Gas Chromatography with Electron-Capture 

Detection (GC/ECD) (Furlong and others, 1996). Known 

concentrations of surrogate organic compounds were added 

to each sample to determine the efficiency of each analysis. 

The percent recovery is the ratio of the analyzed concentration divided by the known concentration, multiplied by 

100 percent. Recoveries of surrogate compounds for the 

GC/ECD method ranged from 43 to 83 percent; therefore, 

concentrations reported for the organic compounds in bed 

sediment may be systematically underrepresented. Concentrations of pesticides and PCBs are generally reported 

without quantitatively correcting for bias that may be represented by the surrogate recoveries. 

Concentrations of trace elements in bed sediment were 

determined by block digestion in Teflon vessels with concentrated acids—hydrochloric acid (HCl), nitric acid 

(HNO3), and perchloric acid (HClO4), and analysis by 

Inductively Coupled Plasma–Mass Spectroscopy (ICP–MS). 

Mercury was determined by the cold vapor method (Briggs 

and Meier, 1999). 

Quality Assurance and Quality Control 

Quality-control (QC) samples were collected during the 

synoptic and temporal surface-water sampling events to 

document bias and variability in the data resulting from the 

collection, processing, shipping, and handling of samples by 

field and laboratory personnel according to procedures in 

Wilde and others (1998). QC included field blanks, replicate samples, and spiked samples. Field blanks were 

collected to identify potential sources of contamination 

during sampling and to assess bias in the concentrations of 

target analytes. Replicate samples were used to quantify 

variability. Spiked samples for pesticides were used to 

determine if there was a loss or gain of target analytes 

because of matrix effects in the sample or because of loss 

during holding times. 

Data summaries from field blanks, replicate samples, and 

spiked field samples for pesticides and nutrients in surface 

water are presented in tables 7 and 8. For pesticide analyses, four field blanks, three sets of replicate samples, and 

one field spike were collected (table 7). All of the pesticide 

concentrations in the blanks were lower than their reporting 

limits. Pesticide concentrations for many of the replicate 

sample pairs were also lower than the detection limits, but an 

estimate of standard deviation was made for all instances 

where pesticides were detected (table 7). Recoveries for 

pesticides in field spikes ranged from 45 to 166 percent, with 

most values between 80 and 120 percent (table 7). For 

nutrients and major ions, one field blank and one set of replicate samples were collected. With the exception of total 

Kjeldahl nitrogen and chloride, the concentrations in the 

blanks were lower than their reporting limits. The relative 

percent difference for the replicate sample pairs was calculated as the difference between the two concentrations 

divided by the average of the two concentrations, multiplied 

by 100 percent (table 8). Estimated standard deviations 

(table 7) ranged from 0.0 to 0.0086 μg/L, and relative percent differences (table 8) ranged from 0.0 percent to 2.9 percent, with the exception of fluoride (with a relative percent 

difference of 40 percent) and dissolved iron (with a relative 

percent difference of 15 percent). The high relative percent 

difference for fluoride is likely because both detections in 

the replicate sample pair (0.2 and 0.3 mg/L) are very close to 

the reporting limit (0.16 mg/L) for this analyte. These 

quality-assurance data indicate that adequate quality-control 

measures were used in the collection of synoptic waterquality, temporal water-quality, and bed-sediment samples. 

Stream-Channel Classification 

Rosgen (1994) developed a classification system for 

natural rivers that groups different types of rivers according 

to their dimension, pattern, profile, and composition. Stream 

types are classified based on bankfull width-to-depth ratio, 

entrenchment ratio, water-surface slope, sinuosity, and 

median particle diameter of the channel materials. The 

Rosgen stream-channel classification system provides an 

effective tool to describe the landforms and channel dimensions within a river valley, and it is often used to aid in 

investigations of sediment supply, stream sensitivity to disturbance, recovery potential of natural channels, channel 

response to changes in flow regime, and fish-habitat potential (Rosgen, 1994; Rosgen, 1996). 

In May 1999, the channel reach downstream of the 

streamflow-gaging station on Rock Creek at Sherrill Drive 

(01648000) was evaluated according to the Rosgen classification system. An approximate 900-ft-long reach was 

selected for field survey and analysis. The reach was limited to approximately 900 ft because of appreciable changes in 

channel width, cross-sectional area, and water-surface slope 

farther downstream. 

The reach cross-section was surveyed for determination 

of data variables that are required for Rosgen stream-channel 

classification (table 9), including bankfull channel width, 

mean and maximum bankfull depths, and the entrenchment 

ratio (Rosgen, 1994; Rosgen, 1996). The cross-section 

location was labeled and marked with rebar at the endpoints 

for future identification by NPS. 

Field sites for the Rosgen stream-channel classification 

were established in the reach with the site farthest upstream 

located at the outside staff gage for the streamflow-gaging 

station, and the site farthest downstream located at the lower 

22 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 7. Quality-assurance and quality-control data for pesticide analyses and selected 

transformation products in surface-water samples collected from February 1999 through 

September 2000, Rock Creek, Washington, D.C.—Continued 

 Table 7. Quality-assurance and quality-control data for pesticide analyses and selected 

transformation products in surface-water samples collected from February 1999 through 

September 2000, Rock Creek, Washington, D.C. 

[Field blanks were collected, and for cases of multiple reporting limits, all reporting limits are given. The standard deviation (SD) is estimated

 from pairs of duplicate samples where the concentrations were above the reporting limit. The formula for the estimated SD is from Taylor

 (1987). Where values were less than the reporting limit, the replicate pairs are indicated as “ND.” All units of concentration are in μg/L 

(micrograms per liter); n, number of samples; <, less than; –, no data available] 

Concentrations (μg/L) in replicate sample pairs 

(n = 3) 

Percent 

Concentrations (μg/L) Estimated recoveries in Analyte in field blanks Sample data standard field spike (n = 4) (pair 1 / pair 2 / pair 3) deviation (n = 1) 

2,4,5–T 1 <0.04 ND / ND / ND – 100 

2,4–D 2 <0.15 , <0.11 ND / ND / ND – 105 

2,4–DB 3 <0.24 , <0.10 ND / ND / ND – 106 

2,6–Diethylaniline <0.003 ND / ND / ND – 89 

3–Hydroxycarbofuran <0.01 , <0.11 ND / ND / ND – – 

Acetochlor <0.002 ND / ND / ND – 115 

Acifluorfen <0.04 , <0.09 ND / ND / ND – 71 

Alachlor <0.002 ND / ND / ND – 129 

Aldicarb sulfone <0.10 ND / ND / ND – – 

Aldicarb sulfoxide <0.02 ND / ND / ND – – 

Aldicarb <0.55 , <0.21 ND / ND / ND – – 

α–HCH 4 <0.002 ND / ND / ND – 104 

Atrazine <0.001 0.040, 0.041 / 0.011, 0.011 / ND 0.0005 92 

Benfluralin <0.002 ND / ND / ND – 101 

Bentazon <0.01 , <0.04 ND / ND / ND – 97 

Bromacil <0.04 , <0.06 ND / ND / ND – – 

Bromoxynil <0.04 ND / ND / ND – 89 

Butylate <0.002 ND / ND / ND – 132 

Carbaryl <0.01 , <0.07 0.094, 0.100 / 0.086, 0.088 / 0.120, 0.100 0.0086 114 

Carbofuran <0.12 , <0.29 ND / ND / ND – – 

1. 2,4,5–Trichlorophenoxyacetic acid. 

2. (2,4–Dichlorophenoxy)acetic acid. 

3. 4–(2,4–Dichlorophenoxy)butyric acid. 

4. α–1,2,3,4,5,6–Hexachlorocyclohexane.

end of the classification reach. At each field site used for breaks in the bank slopes that appeared to be indicative of 

the stream-channel classification, a modified-Wolman the bankfull stage and discharge were surveyed (Leopold 

100-piece pebble count was made according to the percent- and others, 1964; Leopold, 1994). 

ages of riffles, pools, and runs in the reach (Leopold and Channel sinuosity, which is the ratio of stream length to 

others, 1964; Rosgen, 1994; Rosgen, 1996). The 50-percent valley length, was also determined for this classification. 

size fraction from the count typically is used in the classifi- The stream length was measured at the thalweg (deepest 

cation system as the mean bed-material type for classifi- part) of the channel during the field survey of the reach. 

cation of the reach. The valley length for the classification reach was physically 

A field survey was conducted to determine the water- measured as a nearly straight-line distance between the 

surface and channel-bed slopes in the reach. Elevations of lower and upper end-points of the reach. 

Methods of Investigation 23 
Table 7. Quality-assurance and quality-control data for pesticide analyses and selected 

transformation products in surface-water samples collected from February 1999 through 

September 2000, Rock Creek, Washington, D.C.—Continued 

Concentrations (μg/L) in replicate sample pairs 

(n = 3) 

Percent 

Concentrations (μg/L) Estimated recoveries in Analyte in field blanks Sample data standard field spike (n = 4) (pair 1 / pair 2 / pair 3) deviation (n = 1) 

Chloramben, methyl ester <0.14 – / – / – – – 

Chloramben <0.42 ND / ND / ND – – 

Chlorothalonil <0.48 ND / ND / ND – – 

Chlorpyrifos <0.004 0.004, 0.005 / 0.0030, 0.003 / 0.007, 0.008 0.0006 105 

Cynazine <0.004 ND / ND / ND – 127 

Dacthal, monoacid <0.02 , <0.04 ND / ND / ND – 109 

Dacthal <0.002 ND / ND / ND – 112 

Desethylatrazine <0.002 0.070, 0.066 / 0.006, 0.007 / 0.012, 0.012 0.0019 78 

Diazinon <0.002 0.038, 0.036 / 0.036, 0.034 / 0.106, 0.106 0.0012 107 

Dicamba <0.04 ND / ND / ND – 89 

Dichlobenil <1.20 , <0.07 ND / ND / ND – – 

Dichlorprop <0.03 ND / ND / ND – 110 

Dieldrin <0.001 0.006, 0.006 / ND / ND 0.0 88 

Dinoseb <0.04 , <0.14 , <0.06 ND / ND / ND – 84 

Disulfoton <0.017 ND / ND / ND – 69 

Diuron <0.02 , <0.06 0.04, 0.05 / ND / ND 0.0071 – 

DNOC 5 <0.42 ND / ND / ND – 80 

EPTC 6 <0.002 ND / ND / ND – 98 

Ethalfluralin <0.004 ND / ND / ND – 110 

Ethoprop <0.003 ND / ND / ND – 92 

Fenuron <0.01 , <0.07 ND / ND / ND – – 

Fluometuron <0.04 , <0.06 ND / ND / ND – – 

Fonofos <0.003 ND / ND / ND – 91 

Lindane <0.004 ND / ND / ND – 108 

Linuron <0.002 ND / ND / ND – – 

Malathion <0.005 0.006, 0.005 / ND / ND 0.0007 122 

MCPA 7 <0.17 <0.17, 0.04 / ND/ ND – 114 

MCPB 8 <0.14 , <0.13 ND / ND / ND – 94 

Methiocarb <0.03 ND / ND / ND – – 

Methomyl <0.17 , <0.02 ND / ND / ND – – 

5. 4,6–Dinitro–o–cresol. 

6. s–Ethyl dipropylthiocarbamate. 

7. 4–(4–Chloro–2–methylphenoxy)acetic acid. 

8. 4–(4–Chloro–2–methylphenoxy)butanoic acid. 

24 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 7. Quality-assurance and quality-control data for pesticide analyses and selected 

transformation products in surface-water samples collected from February 1999 through 

September 2000, Rock Creek, Washington, D.C.—Continued 

Concentrations (μg/L) in replicate sample pairs 

(n = 3) 

Analyte 

Concentrations (μg/L) 

in field blanks 

(n = 4) 

Sample data 

(pair 1 / pair 2 / pair 3) 

Estimated 

standard 

deviation 

Percent 

recoveries in 

field spike 

(n = 1) 

Methylazinphos 

Methylparathion 

Metolachlor 

Metribuzin 

Molinate 

<0.001 

<0.006 

<0.002 

<0.004 

<0.004 

ND / ND / ND 

ND / ND / ND 

0.019, 0.018 / 0.007, 0.007 / 0.014, 0.013 

ND / ND / ND 

ND / ND / ND 

– 

– 

0.0006 

– 

– 

– 

90 

109 

107 

106 

Napropamide 

Neburon 

Norflurazon 

Oryzalin 

Oxamyl 

<0.003 

<0.01 , <0.07 

<0.02 , <0.04 

<0.31 

<0.02 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

– 

– 

– 

– 

– 

104 

– 

– 

– 

– 

p,p’–DDE 9 

Parathion 

Pebulate 

Pendimethalin 

cis–Permethrin 

<0.006 

<0.004 

<0.004 

<0.004 

<0.005 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

0.012, 0.013 / ND / ND 

ND / ND / ND 

– 

– 

– 

0.0007 

– 

54 

147 

106 

120 

45 

Phorate 

Picloram 

Prometon 

Pronamide 

Propachlor 

<0.002 

<0.05 

<0.018 

<0.003 

<0.007 

ND / ND / ND 

ND / ND / ND 

0.018, 0.017 / 0.007,0.006 / 0.012, 0.012 

ND / ND / ND 

ND / ND / ND 

– 

– 

0.0006 

– 

– 

79 

69 

109 

120 

137 

Propanil 

Propargite 

Propham 

Propoxur 

Silvex 

<0.004 

<0.013 

<0.04 

<0.04 , <0.08 

<0.02 , <0.06 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

– 

– 

– 

– 

– 

111 

136 

– 

– 

99 

Simazine 

Tebuthiuron 

Terbacil 

Terbufos 

Thiobencarb 

<0.005 

<0.010 

<0.007 

<0.013 

<0.002 

0.034, 0.032 / 0.007, 0.007 / 0.018, 0.017 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

ND / ND / ND 

0.0009 

– 

– 

– 

– 

108 

166 

162 

97 

99 

Simazine 

Triallate 

Triclopyr 

Trifluralin 

<0.005 

<0.001 

<0.25 

<0.002 

0.034, 0.032 / 0.007, 0.007 / 0.018, 0.017 

ND / ND / ND 

0.23 , 0.15 / ND / ND 

0.003, 0.003 / <0.002, 0.004 / ND 

0.0009 

– 

0.057 

0.0015 

108 

96 

112 

104 

9. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

Methods of Investigation 25 
.0

Table 8. Quality-assurance and quality-control data for the nutrient and major ion analyses in synoptic and 

temporal surface-water samples from Rock Creek, Washington, D.C. 

[A single field blank was collected. The relative percent difference was calculated as the difference between duplicate values,

 divided by the average of those values, multiplied by100 percent. “Nitrogen, ammonia plus organic nitrogen” is also known as “Kjeldahl

 nitrogen;” N, nitrogen; P, phosphorus; mg/L, milligrams per liter; μg/L, micrograms per liter]

Replicate sample pairs 

Relative 

percent 

difference 

Analytes Units Field blank Sample data (percent) 

Nitrogen, ammonia plus organic nitrogen (dissolved as N) mg/L <0.1 0.37, .37 0 

Nitrogen, ammonia plus organic nitrogen (total as N) mg/L .1 .35, .35 0 

Nitrogen, ammonia (dissolved as N) mg/L < .02 .053, .053 0 

Nitrogen, nitrate plus nitrite (dissolved as N) mg/L < .05 .633, .633 0 

Nitrogen, nitrite (dissolved as N) mg/L < .010 .022, .022 0 

Phosphorus (dissolved as P) mg/L < .004 .020, .020 0 

Phosphorus, phosphate, ortho (dissolved as P) mg/L < .010 .021, .021 0 

Phosphorus (total as P) mg/L < .004 .047, .047 0 

Calcium (dissolved) mg/L < .02 29.4, 29.7 1.0 

Magnesium (dissolved) mg/L < .01 10.1, 10.1 0 

Potassium (dissolved) mg/L < .1 3.4, 3.5 2.9 

Sodium (dissolved) mg/L < .1 24.6, 24.4 .8 

Chloride (dissolved) mg/L .9 57.2, 58.2 1.7 

Fluoride (dissolved) mg/L < .16 .3, .2 40 

Silica (dissolved) mg/L < .1 10.7, 10.8 .9 

Sulfate (dissolved) mg/L < .1 18.4, 18.5 .5 

Iron (dissolved) μg/L <10 70, 60 15 

Manganese (dissolved) μg/L <3 104, 105 1.0 

Table 9. Data-variable values measured in Rosgen stream-channel classification, 

data analyses, and interpretation 

[ft, feet; ft/ft, feet per foot; mm, millimeter; <, less than; >, greater than; %, percent] 

Variables Values Units 

Water surface slope 0.0019 ft/ft 

Sinuosity 1.48 ft/ft 

Mean channel material size <2.0 mm 

Bankfull width 72 ft 

Flood-prone width >200 ft 

Entrenchment ratio >2.2 ft/ft 

Mean bankfull depth 6.39 ft 

Maximum bankfull depth 8.58 ft 

Width/depth ratio 11.3 ft/ft 

Percentage of riffles in reach 10.5 % 

Percentage of pools in reach 65.4 % 

Percentage of runs in reach 25.0 % 

26 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Water-Quality Data 

Pesticides that were applied to the Rock Creek Golf 

Course by the NPS concessioner during water years 1999 

and 2000 included iprodione, dithiopyr, chlorothalonil, 

carbaryl, propiconazole, aluminum tris, mancozeb, propionic 

acid, thiophanate methyl, and lambda-cyhalothrin (table 4). 

Of these pesticides, only chlorothalonil and carbaryl were 

analyzed in this study. Chlorothalonil was not detected in 

any samples; however, carbaryl was detected in three surface-water samples (table 7). All of these detections for 

carbaryl were above recommended water-quality criteria for 

the protection of aquatic life (Canadian Council of Ministers 

of the Environment, 1999). 

Pesticides approved for application by the Rock Creek 

Park staff during water years 1999 and 2000 included 

triclopyr, glyphosate, ammonium amidosulfate, dimethylarsinic acid, and sodium dimethylarsinate (William Yeaman, 

National Park Service, written communs., 2001). Of these 

pesticides, triclopyr and glyphosate were applied to control 

the spread of exotic species growing in the park (tables 5 and 

6). Glyphosate was not analyzed in this study. Triclopyr 

was analyzed and detected in two temporal water-quality 

samples collected from station 01648010 (E 0.23 to 

0.67 μg/L) above the reporting limit (0.07 μg/L); however 

no criteria for the protection of aquatic life for this chemical 

have been set (see appendix B2). 

Synoptic Surface-Water Sampling 

Insecticides detected in the synoptic water-quality 

samples included carbaryl, chlorpyrifos, dieldrin, and 

diazinon (fig. 5; appendix A1). Carbaryl was analyzed by 

NWQL using two different methods because of overlap in 

the analytical schedules. One method (schedule 2050, 

appendix B2) analyzes pesticides in filtered water by 

extraction using a Carbopak B SPE cartridge with analysis 

by HPLC (Werner and others, 1996). The other method 

(schedule 2001, appendix B1) analyzes pesticides in filtered 

water by extraction using a C-18 SPE cartridge with analysis 

by GC/MS (Zaugg and others, 1995). Both of these 

methods of analysis are approved by the USGS. The two 

methods differ in reporting limits and thus have different 

rates of detection for carbaryl, but the concentrations of 

carbaryl in both methods were consistent. Carbaryl was 

detected at site 01648004, but not at site 01648006. 

Station 01648006 is immediately downgradient of the 

golf course. Carbaryl had been applied to all 18 tees of the 

golf course on June 8, 1999, approximately 2 weeks prior to 

synoptic sampling. A hydrograph of rainfall indicates that 

there were three precipitation events between the application 

of carbaryl and the synoptic water-quality sample collection 

(fig. 3)—0.06 in. of rain fell on June 14, 1999, 0.47 in. of 

rain fell on June 15, 1999, and 0.07 in. of rain fell on 

June 17, 1999 (National Oceanic and Atmospheric Administration, 1999). These values are lower than the maximum 

amounts shown in figure 3, and results did not indicate any 

changes in the concentrations of carbaryl in Rock Creek that 

would correlate to the application at the golf course. Station 

01648004, where carbaryl was detected, is on the Pinehurst 

Branch, a tributary upgradient of the golf course. Carbaryl 

has a half-life of approximately 10 days, making its detection indicative of a recent application (Extension Toxicology 

Network, 2001). Carbaryl is a commonly used insecticide 

for agriculture and ornamental gardens, making multiple 

sources of this chemical likely. 

Chlorpyrifos was detected at three of the five synoptic 

water-quality stations (01647998, 01648004, and 

01648010). Two of these stations (01647998 and 

01648010) had concentrations above established freshwater 

criteria (table 10; fig. 5). Station 01647998 is below West 

Beach Drive, and station 01648010 is where Joyce Road 

crosses the creek south of the golf course. Chlorpyrifos was 

not detected at station 01648006 (Rock Creek tributary at 

Golf Course) or station 01648998 (Q Street). 

Dieldrin was detected at station 01648004, but the concentration was not above established freshwater criteria 

(table 10; fig. 5). Dieldrin was not detected at the other four 

synoptic water-quality stations (01647998, 01648006, 

01648010, and 01648998). 

Diazinon was detected at four of the five synoptic waterquality stations (01647998, 01648004, 01648010, and 

01648998). One of these stations (01648998) had a concentration that was above established freshwater criteria 

(table 10; fig. 2). This station is located the farthest downWater-Quality Data 27 
0

Table 10. Summary of contaminants in surface water at Rock Creek Park, Washington, D.C., during 

water years 1999 and 2000, and water-quality criteria for the protection of aquatic life

 [References and abbreviations: A, U.S. Environmental Protection Agency (USEPA) freshwater criteria recommended for protection of aquatic life (USEPA, 1999), including short-term exposure criteria, Criteria Maximum Concentration (CMC), and chronic exposure criteria, Criterion Continuous Concentration 

(CCC); B, USEPA (2001), maximum contaminant level (MCL); C, Canadian Council of Ministers of the Environment, 1999; D, International Joint 

Commission United States and Canada (1989), Great Lakes criteria from the Great Lakes Water-Quality Agreement of 1978; –, no data available; ND, not 

detected; NC, no criteria established for this contaminant; NA, not analyzed; <, less than; E, estimated value (concentration was below the reporting limit and 

warrants less confidence). Synoptic sampling includes samples collected from 5 stations in June 1999. Temporal sampling includes 16 samples collected over 

a 2-year period at station 01648010. Concentration units are in micrograms per liter.] 

Analyte 

USEPA 

freshwater 

criteria A 

 CMC CCC 

_____________ USEPA 

MCL B 

Canadian 

water-quality 

guidelines 

for the 

protection 

of aquatic 

life C 

Great Lakes 

criteria 

for the 

protection 

of aquatic 

life D 

Range of concentrations 

found in Rock Creek 

Synoptic 

sampling, 

June 1999 

Temporal 

sampling 

at station 

01648010 

Number 

of 

samples 

above any 

aquatic 

criteria 

2,4,5–T 1 

2,4–D 2 

2,4–DB 3 

2,6–Diethylaniline 

3–Hydroxycarbofuran 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

70 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

ND 

<0.15 

ND 

ND 

ND 

ND 

<0.11 ­ 0.55 

ND 

ND 

ND 

NC 

NC 

NC 

NC 

NC 

Acetochlor 

Acifluorfen 

Alachlor 

Aldicarb 

sulfone 

Aldicarb 

sulfoxide 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

2 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

NC 

NC 

NC 

NC 

NC 

Aldicarb 

α–HCH 4 

Atrazine 

Benfluralin 

Bentazon 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

3 

– 

– 

1.0 

– 

1.8 

– 

– 

– 

– 

– 

– 

– 

ND 

ND 

<0.001 ­

ND 

ND 

 0.042 

ND 

ND 

<0.001 - 0.145 

<0.002 - 0.004 

ND 

0 

NC 

0 

NC 

NC 

Bromacil 

Bromoxynil 

Butylate 

Carbaryl 

Carbofuran 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

40 

5.0 

5.0 

– 

.2 

1.8 

– 

– 

– 

– 

– 

ND 

ND 

ND 

<0.003 - 

ND 

0.05 

ND 

ND 

ND 

<0.003 - 1.14 

ND 

0 

0 

NC 

3 

0 

1. 2,4,5–Trichlorophenoxyacetic acid. 

2. (2,4–Dichlorophenoxy)acetic acid. 

3. 4–(2,4–Dichlorophenoxy)butyric acid. 

4. α–1,2,3,4,5,6–Hexachlorocyclohexane. 

28 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 10. Summary of contaminants in surface water at Rock Creek Park, Washington, D.C., during water 

years 1999 and 2000, and water-quality criteria for the protection of aquatic life—Continued 

Canadian 

water-quality Great Lakes Range of concentrations Number 

USEPA guidelines criteria found in Rock Creek of 

Analyte 

freshwater 

criteria A 

 CMC CCC 

_____________ USEPA 

MCL B 

for the 

protection 

of aquatic 

life C 

for the 

protection 

of aquatic 

life D 

Synoptic 

sampling, 

June 1999 

Temporal 

sampling 

at station 

01648010 

samples 

above any 

aquatic 

criteria 

Chloramben, – – – – – ND ND NC 

methyl ester 

Chloramben – – – – – ND ND NC 

Chlorothalonil – – – 0.18 – ND ND 0 

Chlorpyrifos – – – .0035 – <0.004 - 0.004 <0.004 - 0.017 10 

Cynazine – – – 2.0 – ND <0.004 - 0.009 0 

Dacthal – – – – – ND <0.002 - E 0.002 NC 

Desethyl- – – – – – <0.002 - E 0.07 E0.010 - E 0.084 NC 

atrazine 

Diazinon – – – – 0.08 <0.002 - E 0.083 E0.003 - 0.307 6 

Dicamba – – – 10 – ND ND 0 

Dichlobenil – – – – – ND ND NC 

Dichlorprop – – – – – ND ND NC 

Dieldrin 0.24 0.056 – – – <0.001 - 0.006 ND 0 

Aldrin – – – – .001 – – 1 

 plus

 Dieldrin 5 

Dinoseb – – 7 .05 – ND ND 0 

Disulfoton – – – – – ND ND NC 

Diuron – – – – – <0.02 - 0.04 <0.02 - E 0.03 NC 

DNOC 6 – – – – – ND <0.42 - E 0.33 NC 

EPTC 7 – – – – – ND ND NC 

Ethalfluralin – – – – – ND ND NC 

Ethoprop – – – – – ND ND NC 

Fenuron – – – – – ND ND NC 

Fluometuron – – – – – ND ND NC 

Fonofos – – – – – ND ND NC 

Glyphosate – – 700 65 – NA NA 0 

Lindane .9 – .2 .01 .01 ND ND 0

 5 Aldrin is quickly transformed to dieldrin in the natural environment, so often only dieldrin is analyzed.

 6. 4,6–Dinitro–o–cresol. 

7. s–Ethyl dipropylthiocarbamate. 

Water-Quality Data 29 
Table 10. Summary of contaminants in surface water at Rock Creek Park, Washington, D.C., during water 

years 1999 and 2000, and water-quality criteria for the protection of aquatic life—Continued 

Analyte 

USEPA 

freshwater 

criteria A 

 CMC CCC 

_____________ USEPA 

MCL B 

Canadian 

water-quality 

guidelines 

for the 

protection 

of aquatic 

life C 

Great Lakes 

criteria 

for the 

protection 

of aquatic 

life D 

Range of concentrations 

found in Rock Creek 

Synoptic 

sampling, 

June 1999 

Temporal 

sampling 

at station 

01648010 

Number 

of 

samples 

above any 

aquatic 

criteria 

Linuron 

Malathion 

MCPA 8 

MCPB 9 

Methiocarb 

– 

– 

– 

– 

– 

– 

0.1 

– 

– 

– 

– 

– 

– 

– 

– 

7.0 

– 

2.6 

– 

– 

– 

– 

– 

– 

– 

ND 

ND 

ND 

ND 

ND 

ND 

<0.005 - 0.274 

ND 

<0.17 ­ E 0.10 

ND 

0 

1 

0 

NC 

NC 

Methomyl 

Methylazinphos 

Methylparathion 

Metolachlor 

Metribuzin 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

7.8 

1.0 

– 

– 

– 

– 

– 

ND 

ND 

ND 

<0.002 - 0.02

ND 

ND 

ND 

ND 

 0.01 - 0.115 

ND 

NC 

NC 

NC 

0 

0 

Molinate 

Napropamide 

Neburon 

Norflurazon 

Oryzalin 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

ND 

ND 

ND 

ND 

ND 

ND 

<0.003 - 0.033 

ND 

ND 

ND 

NC 

NC 

NC 

NC 

NC 

Oxamyl 

p,p’–DDE 10 

DDT plus 

metabolites 11 

Parathion 

Pebulate 

– 

– 

– 

0.065

– 

– 

– 

– 

 .013 

– 

200 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

0.003 

– 

– 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

NC 

NC 

0 

0 

NC 

Pendimethalin 

cis–Permethrin 

Phorate 

Picloram 

Prometon 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

500 

– 

– 

– 

– 

29 

– 

– 

– 

– 

– 

– 

<0.004 - E 0.012 

ND 

ND 

ND 

<0.018 - 0.029 

<0.004 - 0.036 

ND 

ND 

ND 

E 0.004 - 0.072 

NC 

NC 

NC 

0 

NC

 8. 4–(4–Chloro–2–methylphenoxy)acetic acid.

 9. 4–(4–Chloro–2–methylphenoxy)butanoic acid. 

10. 1,1,–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

11. 1,1,1–Trichloro–2,2–bis(p–chlorophenyl)ethane. 

30 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Table 10. Summary of contaminants in surface water at Rock Creek Park, Washington, D.C., during water 

years 1999 and 2000, and water-quality criteria for the protection of aquatic life—Continued 

Analyte 

USEPA 

freshwater 

criteria A 

 CMC CCC 

_____________ USEPA 

MCL B 

Canadian 

water-quality 

guidelines 

for the 

protection 

of aquatic 

life C 

Great Lakes 

criteria 

for the 

protection 

of aquatic 

life D 

Range of concentrations 

found in Rock Creek 

Synoptic 

sampling, 

June 1999 

Temporal 

sampling 

at station 

01648010 

Number 

of 

samples 

above any 

aquatic 

criteria 

Propyzamide 

Propachlor 

Propanil 

Propargite 

Propham 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

ND 

NC 

NC 

NC 

NC 

NC 

Propoxur 

Silvex 

Simazine 

Tebuthiuron 

Terbacil 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

50 

4 

– 

– 

– 

– 

10 

1.6 

– 

– 

– 

– 

– 

– 

ND 

ND 

<0.005 - 0.046 

ND 

ND 

ND 

ND 

<0.005 - 0.083 

<0.010 - 0.010 

ND 

NC 

NC 

0 

0 

NC 

Terbufos 

Thiobencarb 

Triallate 

Triclopyr 

Trifluralin 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

–

– 

–

– 

– 

 .24 

– 

 .20 

– 

– 

– 

– 

– 

ND 

ND 

ND 

ND 

<0.002 - 0.003 

ND 

ND 

ND 

<0.250 - 0.260 

<0.002 - 0.006 

NC 

NC 

0 

NC 

0 

stream of the five synoptic water-quality stations. This concentration may indicate that diazinon has accumulated in the 

sediment near the downstream station. 

Herbicides detected at four of the five stations (01647998, 

01648004, 01648010, and 01648998) in the synoptic survey 

included atrazine, metolachlor, prometon, and simazine (fig. 6; 

appendix A1), whereas diuron was detected only at station 

01648010. These chemicals were not directly applied to 

Rock Creek Park or Rock Creek Golf Course by NPS, and they 

are more extensively used in agricultural areas than in urban/ 

suburban areas (table 3). Each of these chemicals is moderately to highly persistent in water, with half-lives ranging from 

4–6 weeks to 1 year (Extension Toxicology Network, 2001). 

None of the herbicides found in surface water during the 

synoptic sampling were found in concentrations that were 

greater than established freshwater criteria for the protection of 

aquatic life (table 10); however, there are no established freshwater criteria for diuron or prometon (table 10; appendix A1).

 The total concentrations of insecticides and herbicides 

measured at the five synoptic water-quality stations are 

presented in figure 7. No pesticides were detected at station 

01648006, which is in a small tributary draining directly from 

the golf course into Rock Creek. Therefore, the pesticides that 

were applied to Rock Creek Golf Course were not observed in 

the synoptic water-quality samples. The differences in pesticide concentrations among the five synoptic stations were not 

appreciable enough to make any conclusions about the spatial 

variability in water quality. There were no noticeable correlations between pesticide usage in the basins and observed 

concentrations in the stream segments. 

Field measurements, major ions, and nutrients were measured at the five synoptic water-quality stations. These 

measurements included discharge, dissolved oxygen, pH, 

specific conductance, air and water temperature, major ions, 

nitrogen, phosphorus, iron, manganese, and suspended 

sediment. There were no unusually high concentrations or 

Water-Quality Data 31 
measurements for any of these parameters (appendix A2). 

These measurements were based on a single base-flow 

synoptic sampling event and do not account for variations 

that may occur seasonally or during storm events. 

Temporal Surface-Water Sampling 

Station 01648010, located where Joyce Road crosses 

Rock Creek, was sampled for pesticides over a range of 

flow conditions from February 18, 1999 through 

September 26, 2000. Insecticides that were detected at the 

highest concentrations and most frequently at this station 

were chlorpyrifos, diazinon, carbaryl, and malathion. 

Chlorpyrifos and diazinon are used for a variety of purposes 

in agricultural and urban/suburban areas, including the 

control of cockroaches, ants, fleas, and other insects in 

residential housing. Malathion is used to control mosquitoes, flies, and other insects (Extension Toxicology Network, 

2001). Insecticide concentrations were above the freshwater criteria in numerous samples. Herbicides that were 

detected at the highest concentrations and most frequently at 

this station were atrazine, metolachlor, prometon, and 

simazine (table 10; appendix A1). 

Time-series plots of discharge at station 01648010 with 

overlays of the concentrations of total insecticides and total 

herbicides measured in surface water are shown in figures 8 

and 9. The seasonal behavior of both groups of chemicals 

also are shown. Whereas there appears to be some measurable level of pesticides year round, there still is a strong 

indication of seasonality, whereby higher concentrations are 

observed for both groups of pesticides from May through 

July. This result corresponds well to the growing season for 

agriculture and to the general timing of residential lawn 

treatments. A strong seasonal component for pesticide 

concentrations in the Potomac River Basin was also 

observed during the NAWQA urban/suburban and 

agricultural pesticide studies (Ator and others, 1998). River 

discharge appears to be less significant when analyzing the 

concentrations of pesticides in Rock Creek than periods of 

pesticide application. 

A time-series plot of discharge with an overlay of the 

total concentrations of herbicides from two groups—those 

that are used most commonly in an urban setting (2,4-D and 

MCPA), and those used most commonly in an agricultural 

setting (atrazine, cyanazine, and metolachlor)—is shown in 

figure 10. These usages are not exclusive, except for 

metolachlor, but provide good general indicators of the types 

of usage in the basin (Hoffman and others, 2000). The 

seasonal behavior of herbicides in Rock Creek is also 

apparent in this plot, although the maximum concentrations 

for each group occurred at different times of the year. The 

urban-use herbicides had two small peaks, one in early 

spring of 1999, one in mid-summer of 2000, and one large 

peak in early autumn of 2000. The sporadic peaks of the 

urban-use herbicides likely reflect residential lawn and 

garden treatments, which may vary during the year. Agricultural herbicides consistently peaked in spring and early 

summer during the regular crop-growing season, which corresponds with the times of greatest application. 

32 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Water-Quality Data 33 
34 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Water-Quality Data 35 
A plot of the exceedance ratios of chlorpyrifos, diazinon, 

carbaryl, and malathion above aquatic life criteria over the 

2-year study period is shown in figure 11. The exceedance 

ratios on the y-axis are calculated as the pesticide concentration measured on any particular day normalized to the 

aquatic life criteria for each pesticide. Values equal to 1 

indicate that the pesticide concentration is equal to the 

aquatic criteria, and values greater than 1 indicate that the 

pesticide concentration was above the criteria. 

During water years 1999 and 2000, the peak detection 

times and concentrations above the aquatic criteria for 

diazinon, carbaryl, and malathion occurred during the late 

spring to early summer months of May and June. As discussed previously, these peak concentrations most likely 

correspond to peak application times for agricultural and 

residential use of these chemicals. The concentrations of 

chlorpyrifos above the aquatic criteria occurred more randomly throughout the study period and indicate that usage 

for this chemical is not seasonal, and is possibly from 

multiple sources. 

The Rock Creek Basin is a mixture of urban/suburban 

and agricultural land use. Other studies generally show that 

urban/suburban areas tend to have higher insecticide concentrations, and agricultural areas tend to be higher in herbicides (Barbash and others, 1997; Hoffman and others, 2000). 

Approximately equal total concentrations of herbicides and 

insecticides (over the 20-month sampling period) were found 

during this study, indicating that the water quality in Rock 

Creek is affected by the surrounding land use. 

36 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Sediment-Quality Data 

Bed-sediment samples were collected at stations 

01647997, 01648000, and 01648998 in Rock Creek in 

August 1999. The station farthest upstream (01647997) is 

on the Portal Branch, which is a tributary that drains into 

Rock Creek (fig. 2). Station 01648000 is located on the 

mainstem of Rock Creek, just north of the golf course, 

and station 01648998, which is also on the mainstem of 

Rock Creek, is the station farthest downstream. Organic 

compound and trace-element data in bed-sediment samples 

are summarized in table 11. Published sediment-quality 

guidelines for the protection of aquatic life in freshwater 

environments, as well as the number of samples with concentrations above these sediment criteria, are included in the 

table. 

PAH compounds are formed in the environment primarily during combustion processes, such as the burning of 

fossil fuels, wood, trash, or garbage (Agency for Toxic 

Substances and Disease Registry, 2001). Many PAH compounds occur naturally, but they are generally found in 

higher concentrations in urban areas where there are more 

sources of combustion (such as automobiles, coal, and wood 

burning) and chemical manufacturing. PAH compounds are 

released into the atmosphere as vapors or small particles, and 

enter the basins either as atmospheric deposition or in runoff 

from urban areas. These compounds tend to be insoluble in 

water and reside in the particulate phase in aquatic environments. Thus, suspended and bed sediments may act as 

reservoirs of PAHs in aquatic systems (Agency for Toxic 

Substances and Disease Registry, 2001). 

The total concentrations of PAHs found at each station 

are shown in figure 12. The station farthest upstream 

(01647997) had the lowest measured concentration of PAHs. 

This station (01647997) is on the Portal Branch. The two 

stations on the mainstem of Rock Creek (01648000 and 

01648998) had similar concentrations of total PAHs, and the 

concentrations at both of these stations were higher than 

those detected in the upstream station (01647997). The 

PAHs in the sediments in Rock Creek may be sorbed to sediment particles and transported downstream, which may 

explain the higher concentrations at the downstream stations, 

where more sediment has accumulated. 

Sediment-quality criteria for the protection of aquatic 

life from published sources also are included in table 11. 

MacDonald (1994) and Long and Morgan (1990) give two 

thresholds of criteria. The TEL (threshold effect level) is 

the lowest level where effects may be expected from chronic 

exposure (occurring over an extended period of time, usually 

7 years to a lifetime) to that compound. The PEL (probable 

effect level) is a higher concentration where effects on 

benthic biota are more likely from acute exposure (usually 

characterized as lasting no longer than a day). The 

Canadian sediment quality guidelines (Canadian Council of 

Ministers of the Environment, 1999) provide similar or 

interim criteria for freshwater benthic biota, some of which 

are shared with the marine values for the TEL and PEL. 

These data provide an assessment based on the literature on 

toxicity of various compounds or trace elements to different 

biota, and will vary as new information becomes available. 

All of the low- and high-molecular weight PAH compounds that were analyzed in Rock Creek bed sediments 

were found at two of the three stations, and most of these 

compounds were found in concentrations above at least one 

of the sediment criteria (table 11). Sediment criteria are 

available for only 6 of the 16 low-molecular-weight PAHs 

Sediment-Quality Data 37 
Table 11. Summary of contaminants in bed sediment at Rock Creek Park, Washington, D.C., and 

published sediment-quality criteria for the protection of aquatic life

 [References and abbreviations: A, Long and Morgan (1990) and MacDonald (1994) sediment assessment guidelines for Florida coastal

waters, including the threshold effects level (TEL), which is the lowest concentration that might cause effects from chronic exposure, and

 the probable effects level (PEL), which is the concentration at which acute effects are more likely; B, Canadian Council of Ministers of the Environment (1999) interim freshwater sediment quality guidelines (ISQG) and PEL; –, no data available; E, estimated value (concentration

was below the reporting limit and warrants less confidence); NC, no criteria established for this contaminant; <, less than; LMW PAHs,

 low-molecular-weight polycyclic aromatic hydrocarbons; HMW PAHs, high-molecular-weight polycyclic aromatic hydrocarbons;

 PCBs, polychlorinated biphenyls; μg/kg, microgram per kilogram; mg/kg, milligram per kilogram; sediment samples were collected from

stations 01647997, 01648000 and 01648998 in August 1999] 

Sediment 

assessment 

guidelines for 

Florida 

coastal waters A 

Canadian 

water-quality 

guidelines for the 

protection of 

aquatic life B 

Concentrations 

of contaminants 

at three sediment stations

 in Rock Creek 

Number of 

samples 

above any 

sediment 

criteria _____________________ _____________________ 

Analyte TEL PEL ISQG PEL 01647997 01648000 01648998 

LOW-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC HYDROCARBONS (μg/kg) 

4,5-Methylene- – – – – E 20 130 120 NC 

phenanthrene 

Anthraquinone – – – – 100 380 280 NC 

Acenaphthene 6.71 88.9 6.71 88.9 <50 E 10 E 30 2 

Acenaphthylene 5.87 128 5.87 128 E 40 70 E 60 3 

Acridine – – – – <50 60 E 40 NC 

2-Methyl- – – – – E 10 E 20 E 20 NC 

 anthracene 

Anthracene 46.9 245 46.9 245 60 160 190 3 

Carbazole – – – – E 10 130 110 NC 

p-Cresol – – – – <50 80 400 NC 

Dibenzothiophene – – – – E 20 60 E 50 NC 

Fluorene 21.1 144 21.2 144 < 50 E 30 E 40 2 

1-Methyl- – – – – <50 E 30 E 30 NC 

 phenanthrene 

2,6-Dimethyl- – – – – <50 E 30 E 40 NC 

 naphthalene 

Naphthalene 34.6 391 34.6 391 <50 E 40 <100 1 

Phenanthrene 86.7 544 41.9 515 240 930 830 3 

Phenol – – – – <50 E 30 E 40 NC 

Total LMW PAHs 312 1,442 – – 500 2,190 2,280 3 

38 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
[Concentrations of bed sediment were collected at three stations in Rock Creek in August 1999. Published sediment-quality criteria for the

 protection of aquatic life are presented for comparison. Sediment Assessment Guidelines for Florida Coastal Waters (MacDonald, 1994; Long and

 Morgan, 1990) provide a threshold effect level (TEL), the lowest level that might cause effects from chronic exposure, and a Probable Effects Level

 (PEL), where effects are more likely. Canadian sediment quality guidelines (CCME, 1995) provide an interim freshwater sediment quality

 guidelines (ISQG) and a PEL for selected constituents; References, A, Long, E.R., and Morgan, L.G. 1990; B, MacDonald, D.D., 1994, 149 p;

 C, Canadian Council of Ministers of the Environment (CCME), 1999, 5 p; Note: E, estimated value (constituent was detected but there is less confidence in the precision of this value); LMW, Low Molecular Weight; HMW, High Molecular Weight; NC, no established criteria set for this

 compound; –, no data available; μg/kg, micrograms per kilograms; mg/kg, milligrams per kilograms]

Table 11. Summary of contaminants in bed sediment at Rock Creek Park, Washington, D.C., and 

published sediment-quality criteria for the protection of aquatic life—Continued 

Sediment 

assessment 

guidelines for 

Florida 

coastal waters A 

Canadian 

water-quality 

guidelines for the 

protection of 

aquatic life B 

Concentrations 

of contaminants 

at three sediment stations

 in Rock Creek 

Number of 

samples 

above any 

sediment 

criteria _____________________ _____________________ 

Analyte TEL PEL ISQG PEL 01647997 01648000 01648998 

HIGH-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC HYDROCARBONS (μg/kg) 

Benz(a)anthracene 74.8 693 31.7 385 210 690 660 3 

Benzo(a)pyrene 88.8 763 31.9 782 240 880 810 3 

Benzo[b]fluoranthene – – – – 160 820 880 NC 

Benzo[ghi]perylene – – – – 140 640 420 NC 

Benzo[k]fluoranthene – – – – 160 820 880 NC 

Chrysene 108 846 57.1 862 260 1,200 1,000 3 

Dibenz(a,h) 6.22 135 6.22 135 E 40 140 210 3 

anthracene 

Fluoranthene 113 1,494 111 2355 500 2,000 1,600 3 

Indeno[1,2,3-cd] – – – – 180 750 550 NC 

pyrene 

Pyrene 153 1,398 53.0 875 410 1,600 1200 3 

Total HMW PAHs 655 6,676 – – 2,300 9,540 8,210 3 

Total PAHs 1,684 16,770 – – 2,800 11,730 10,490 3 

TOTAL POLYCHLORINATED BIPHENYLS (μg/kg) 

Total PCBs 21.6 189 34.1 277 <50 80 50 2 

Sediment-Quality Data 39 
[Concentrations of bed sediment were collected at three stations in Rock Creek in August 1999. Published sediment-quality criteria for the

 protection of aquatic life are presented for comparison. Sediment Assessment Guidelines for Florida Coastal Waters (MacDonald, 1994; Long and

 Morgan, 1990) provide a threshold effect level (TEL), the lowest level that might cause effects from chronic exposure, and a Probable Effects Level

 (PEL), where effects are more likely. Canadian sediment quality guidelines (CCME, 1995) provide an interim freshwater sediment quality

 guidelines (ISQG) and a PEL for selected constituents; References, A, Long, E.R., and Morgan, L.G. 1990; B, MacDonald, D.D., 1994, 149 p;

 C, Canadian Council of Ministers of the Environment (CCME), 1999, 5 p; Note: E, estimated value (constituent was detected but there is less confidence in the precision of this value); LMW, Low Molecular Weight; HMW, High Molecular Weight; NC, no established criteria set for this

 compound; –, no data available; μg/kg, micrograms per kilograms; mg/kg, milligrams per kilograms]

Table 11. Summary of contaminants in bed sediment at Rock Creek Park, Washington, D.C., and 

published sediment-quality criteria for the protection of aquatic life—Continued 

Sediment 

assessment 

guidelines for 

Florida 

coastal waters A 

Canadian 

water-quality 

guidelines for the 

protection of 

aquatic life B 

Concentrations 

of contaminants 

at three sediment stations

 in Rock Creek 

Number of 

samples 

above any 

sediment 

criteria _____________________ _____________________ 

Analyte TEL PEL ISQG PEL 01647997 01648000 01648998 

PESTICIDES (μg/kg) 

Aldrin – – – – <1 <1 <1 NC 

Chlordane 2.26 4.79 4.50 8.87 4 13 13 3 

(cis- plus trans-) 

o,p’–DDD 1 – – – – <1 3 <1 NC 

p,p’–DDD 2 1.22 7.81 3.54 8.51 2 E 4 6 E 3 

o,p’–DDE 3 – – – – <1 <1 <1 NC 

p,p’–DDE 4 2.07 – 1.42 6.75 2 4 7 3 

p,p’–DDT 5 1.19 4.77 1.19 4.77 7 4 8 3 

Total DDT 3.89 51.7 – – 11 15 21 3 

Dieldrin .715 4.3 2.85 6.67 2 3 3 3 

Endosulfan – – – – <1 <1 <1 NC 

Endrin – – 2.67 62.4 <2 <2 <2 0 

Heptachlor – – – – <1 <1 <1 NC 

Heptachlor epoxide – – .60 2.74 <1 2 2 2 

Lindane .32 .99 .94 1.38 <1 <1 <1 0 

Mirex – – – – <1 <1 <1 NC 

1. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethane. 

2. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethane. 

3. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethylene. 

4. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

5. 1,1,1–Trichloro–2,2–bis(p-chlorophenyl)ethane. 

40 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
[Concentrations of bed sediment were collected at three stations in Rock Creek in August 1999. Published sediment-quality criteria for the

 protection of aquatic life are presented for comparison. Sediment Assessment Guidelines for Florida Coastal Waters (MacDonald, 1994; Long and

 Morgan, 1990) provide a threshold effect level (TEL), the lowest level that might cause effects from chronic exposure, and a Probable Effects Level

 (PEL), where effects are more likely. Canadian sediment quality guidelines (CCME, 1995) provide an interim freshwater sediment quality

 guidelines (ISQG) and a PEL for selected constituents; References, A, Long, E.R., and Morgan, L.G. 1990; B, MacDonald, D.D., 1994, 149 p;

 C, Canadian Council of Ministers of the Environment (CCME), 1999, 5 p; Note: E, estimated value (constituent was detected but there is less confidence in the precision of this value); LMW, Low Molecular Weight; HMW, High Molecular Weight; NC, no established criteria set for this

 compound; –, no data available; μg/kg, micrograms per kilograms; mg/kg, milligrams per kilograms]

Table 11. Summary of contaminants in bed sediment at Rock Creek Park, Washington, D.C., and 

published sediment-quality criteria for the protection of aquatic life—Continued 

Analyte 

Sediment 

assessment 

guidelines for 

Florida 

coastal waters A 

TEL PEL 

_____________________

Canadian 

water-quality 

guidelines for the 

protection of 

aquatic life B 

ISQG PEL 

_____________________ 

Concentrations 

of contaminants 

at three sediment stations

 in Rock Creek 

01647997 01648000 01648998 

Number of 

samples 

above any 

sediment 

criteria 

PHTHALATES (μg/kg) 

Bis(2-ethylhexyl) 

phthalate 

Butylbenzyl 

phthalate 

Diethyl phthalate 

Dimethyl phthalate 

182 

– 

– 

– 

2,647 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

420 

E 30 

E 10 

<50 

2,200 

90 

E 20 

<50 

2,100 

E 50 

<100 

<100 

3 

NC 

NC 

NC 

Dioctylphthalate 

Di-n-butyl phthalate 

– 

– 

– 

– 

– 

– 

– 

– 

60 

E 30 

<50 

90 

180 

E 50 

NC 

NC 

Total Phthalates – – – – 550 2,400 2,380 NC 

TRACE ELEMENTS (mg/kg) 

Arsenic 

Cadmium 

Chromium 

Copper 

Lead 

7.24 

.676 

52.3 

18.7 

30.2 

41.6 

4.21 

160 

108 

112 

5.90 

.60 

37.3 

35.7 

35.0 

17.0 

3.5 

90.0 

197 

91.3 

5.70 

1.30 

110 

150 

110 

6.90 

1.20 

150 

130 

98 

7.40 

1.50 

160 

170 

150 

2 

3 

3 

3 

3 

Mercury 

Nickel 

Silver 

Zinc 

.13 

15.9 

.733 

124 

.696 

42.8 

1.77 

271 

.17 

– 

– 

123 

.486 

– 

– 

315 

.21 

70 

.50 

410 

1.40 

94 

.60 

370 

.32 

99 

.50 

450 

3 

3 

0 

3 

Sediment-Quality Data 41 
that were analyzed. Concentrations of these six low-molecular-weight PAHs were above their respective TELs at all 

three stations from which bed sediments were collected; 

however, the concentration of only one of these compounds 

(phenanthrene) was above the PEL at stations 01648000 and 

01648998. Sediment criteria are available for only 6 of the 

10 high-molecular-weight PAHs that were analyzed. Concentrations of all six of these high-molecular-weight PAHs 

were above their respective TELs at all three stations. Concentrations were above the PELs for benzo(a)pyrene, chrysene, dibenz(a,h)anthracene, fluoranthracene, and 

indeno[1,2,3-cd]pyrene at station 01648000, and for 

benzo(a)pyrene, chrysene, dibenz(a,h)anthracene, and 

fluoranthracene at station 01648998. These concentrations 

indicate that the toxicity to aquatic life may be higher at 

downstream stations (01648000 and 01648998) than toxicity 

at the Portal Branch (station 01647997). 

PCBs are synthetic organic compounds; there are no 

known natural sources of PCBs in the environment (Agency 

for Toxic Substances and Disease Registry, 2001). PCBs 

most commonly enter the environment from leaking 

electrical fixtures, where they have been used in the past as 

non-flammable insulating materials. PCBs are relatively 

soluble in water, but also can attach to sediment particles and 

organic matter. These compounds have a strong potential 

for bioaccumulation and biomagnification (Agency for 

Toxic Substances and Disease Registry, 2001). Production 

of PCBs was stopped in 1997 because of documented harmful effects, but a number of transformers and other types of 

electrical equipment that contain PCBs have not been 

decommissioned. PCBs were detected in bed sediment at 

the two mainstem stations (01648000 and 01648998), but 

not at station 01647997 (fig. 13). The concentrations of 

PCBs at both of the mainstem stations were above the TEL 

but not the PEL for bed sediment. 

Selected pesticides and transformation products were 

also analyzed in the bed-sediment samples collected from all 

three stations. Complete results are presented in appendixes 

A3 and A4, and a summary of parent compounds and their 

transformation products are presented in appendix C. A 

summary of the concentrations of selected pesticides and 

transformation products that were analyzed in the bed-sediment samples is listed in table 11. Chlordane (cis- plus 

trans-) concentrations were above only the TEL in the sample collected from station 01647997. Chlordane concentrations were above both the TEL and the PEL in samples collected from stations 01648000 and 01648998. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and dieldrin 

concentrations were above only the TEL in samples 

collected from all three stations. 1,1-Dichloro-2,2-bis(pchlorophenyl)ethylene (DDE) concentrations were above 

both the TEL and the PEL in the sample collected from 

station 01648998, but only above the TEL in samples collected from stations 01647997 and 01648000. DDT concentrations were above both the TEL and the PEL in samples 

collected at all three bed sediment stations. Heptachlor 

epoxide concentrations were above only the TEL in samples 

collected from stations 01648000 and 01648998. All of 

these compounds are toxic organochlorines that have been 

either banned or discontinued for usage. Therefore, they are 

“legacy” compounds, or transformation products of these 

compounds, from earlier applications. A summary of the 

total DDT compounds (DDT, DDE, and DDD) that were 

found at each of the bed-sediment stations at Rock Creek is 

shown in figure 14. The concentration of DDT at station 

01647997 is greater than the sum of its two transformation 

products, DDE and DDD; however, the concentration of 

DDT at stations 01648000 and 01648998 is lower than the 

sum of its transformation products. 

Overall, the two mainstem stations (01648000 and 

01648998) appear to have higher concentrations of DDT and 

its transformation products (15 and 21 μg/kg, or micrograms 

per kilogram) than station 01647997 (11 μg/kg). The total 

organic carbon concentration was lower at station 01647997 

(2.7 percent) when compared to concentrations at the two 

mainstem stations (4.3 and 5.7 percent). The total concentrations of DDT, DDE, and DDD at each station correlate 

well with the percentage of total organic carbon in the 

sediment (Pearson correlation coefficient, r equals 0.988). 

These concentrations indicate that these three compounds 

are likely associated with the organic fraction of the sediments. 

Phthalate compounds are a group of manmade chemicals 

that are commonly used in the production of plastic materials. They can also be used as ingredients in paints, inks, 

42 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
pesticides, cosmetics, and a number of other industrial products. These compounds are generally released to the 

environment from factories or landfills and waste disposal 

sites. Phthalates are very particle-reactive and tend to 

accumulate in sediments. Aquatic criteria currently are only 

available for bis(2-ethylhexyl)phthalate. In Rock Creek 

sediments, this phthalate compound was above the TEL at 

all three stations (01647997, 01648000, and 01648998). 

The two mainstem stations had concentrations that were 

close to but not above the PELs. 

Concentrations of trace elements were measured at the 

three bed-sediment stations in Rock Creek. Trace elements 

can come from a variety of natural and manmade sources, 

but they generally tend to be higher in populated areas 

(Daskalakis and O’Conner, 1995; Rice, 1999). Enrichment 

of lead, copper, mercury, zinc, and sometimes cadmium and 

chromium is common in urban streams. Some trace elements, such as copper, arsenic, and zinc, can have agricultural sources as well. 

The concentrations of metals in bed sediment were 

above the TEL at all three bed-sediment sampling stations 

for all of the heavy metals except arsenic and silver. The 

criteria were above the PEL at least once each for chromium, 

copper, lead, mercury, nickel, and zinc. Arsenic concentrations were close to the TEL at all three stations. In general, 

the spatial distribution of the concentrations of trace elements did not follow the same pattern that was evident for 

organic compounds. Chromium and nickel appeared to 

have higher concentrations in the two mainstem stations, but 

there are not enough data to determine if this difference is 

statistically significant. 

Data Analysis and Comparison of StreamChannel Classifications 

Bankfull indicators from the longitudinal survey were 

plotted, and a line was drawn through the bankfull indicator 

elevations and extended to the location of the staff gage at 

the streamflow-gaging station. The line indicated a bankfull 

stage of 6.75 ft, gage datum, as of May 1999. Based on 

data, the stage-discharge rating for the station indicates a 

bankfull discharge of about 1,530 ft3/s (cubic feet per second). This discharge corresponds to a flood event of 

approximately 1.4 years, based on analysis of the flood 

peaks that have occurred since the upstream lakes were constructed in the basin beginning in 1966 (data on file, U.S. 

Geological Survey, Baltimore, Maryland). 

Longitudinal and cross-sectional data were then used to 

calculate the variables necessary for classification. These 

variables are summarized in table 9. Based on the slope, 

width/depth ratio, entrenchment ratio, sinuosity, and mean 

channel material size, the reach was classified as a C5 channel according to the Rosgen stream-channel classification 

system. This classification indicates that this reach of 

Rock Creek can be described as a single thread channel that 

is slightly entrenched, with a moderate width/depth ratio and 

high sinuosity. The predominant channel material is sand. 

The applicability of this Rosgen classification depends upon 

the stability of the stream channel, the dynamic nature of 

recharge to Rock Creek, the large amount of impervious 

surfaces in the basin, and the partial regulation of the flows 

from Lake Needwood and Lake Bernard Frank upstream of 

the streamflow-gaging station in Montgomery County, 

Maryland. Regulation of the flows currently affects about 

25 mi2 of the 62 mi2 of the basin upstream of the streamflow-gaging station (James and others, 2001). 

An earlier Rosgen stream-channel classification had been 

performed in the same reach for NPS by a consultant in 1989 

(Douglas Curtis, National Park Service, written commun., 

2001). In the 1989 classification, the reach was classified as 

a C3 channel (Douglas Curtis, National Park Service, written 

commun., 2001), and the predominant channel material was 

cobbles. A comparison of the 1989 and 1999 Rosgen 

evaluations indicate the presence of additional deposits of 

sand that are being stored in the reach and currently overlay 

the older cobble channel materials. 

Data Analysis and Comparison of Stream-Channel Classifications 43 
Summary and Conclusions 

In 1999, the U.S. Geological Survey began an investigation of the water quality and sediment quality of Rock 

Creek (in the Washington, D.C. area) in cooperation with the 

National Park Service, to determine the effect of surrounding 

land use. From February 1999 through September 2000, 

synoptic water-quality, temporal (over a 20-month period) 

water-quality, and bed-sediment samples were collected and 

analyzed. Eighty-six pesticide compounds (parent compounds and selected transformation products) were analyzed 

in the synoptic and temporal water-quality samples. A total 

of 17 polycyclic aromatic hydrocarbons, 21 pesticides, 6 

phthalates, 10 trace elements, and polychlorinated biphenyls 

(total) were analyzed from the bed-sediment samples. 

Of the pesticide compounds in the synoptic and temporal 

water-quality samples, five were detected at concentrations 

above the published recommended criteria for the protection 

of aquatic life: carbaryl, chlorpyrifos, diazinon, dieldrin, 

and malathion. Of the 17 polycyclic aromatic hydrocarbons 

analyzed in bed-sediment samples, 12 were detected at concentrations above the published recommended criteria for 

the protection of aquatic life: acenaphthene, acenaphthylene, anthracene, fluorene, naphthalene, phenanthrene, 

benz(a)anthracene, benzo(a)pyrene, chrysene, dibenz­

(a,h)anthracene, fluoranthene, and pyrene. All pesticides 

and pesticide transformation products that were above the 

aquatic criteria in bed sediments are currently banned and 

provide evidence of past usage: chlordane; 1,1,1–trichloro2,2–bis(p–chlorophenyl)ethane (DDT); 1,1–dichloro–2,2– 

bis(p–chlorophenyl)ethylene (DDE); 1,1–dichloro–2,2– 

bis(p–chlorophenyl)ethane (DDD); dieldrin; and heptachlor 

epoxide. Various phthalate compounds were also found in 

bed sediment and at least one of these compounds, bis(2– 

ethylhexyl)phthalate, may indicate a risk to the health of 

benthic biota. The trace elements that were measured in bed 

sediment were above the threshold effect level at all three 

stations for all of the heavy metals except arsenic and silver, 

and above the probable effect level at least once each for 

chromium, copper, lead, mercury, nickel, and zinc. 

Aluminum and iron concentrations also appeared to be very 

similar among the three bed-sediment stations, indicating 

similar matrices in the bed sediments. 

Data from this study indicate that there are a number of 

contaminants in Rock Creek with concentrations that are 

above established criteria for the protection of aquatic life, 

both in the water column and in bed sediment. The additive 

and possibly synergistic effects of these contaminants on the 

biota are beyond the scope of this report. Information on the 

long-term chronic effects of many of these contaminants is 

limited. The results of this study strongly indicate that the 

water and sediment quality may adversely affect the biota in 

this environment; however, the biota in Rock Creek were not 

assessed in this study. 

The Rock Creek Basin is approximately 46 percent 

urban/suburban and 21 percent agricultural. Almost all of 

the agricultural land use is in the upper part of the basin 

north of Rock Creek Park. Land use in the lower part of the 

basin, south of the Maryland–Washington, D.C. boundary, is 

approximately 61 percent urban/suburban. The results of 

the current study indicate that both urban and agricultural 

land use have influenced the water and sediment quality of 

Rock Creek within the park boundaries. Pesticides are 

likely coming from multiple sources, and it is difficult to 

make correlations between specific sources and the concentrations of these compounds that are found in the river 

and sediments. 

In May 1999, a reach of approximately 900 feet near 

station 01648000, near Sherrill Drive, was classified according to the Rosgen system of stream-channel classification. 

At this time, Rock Creek was classified as a C5 channel 

according to the Rosgen system. A previous classification 

of this same reach, performed in 1989, had classified this 

reach as a C3 channel according to the Rosgen system. 

These two classifications indicate that sands and other finegrained sediments, probably transported from development 

within the basin, are being deposited in Rock Creek and 

currently overlie the original cobble channel materials. 

These sediments may act as an ongoing reservoir for polycyclic aromatic hydrocarbons, polychlorinated biphenyls, 

pesticides and their transformation products, phthalates, and 

trace elements, presenting a long-term source of these 

compounds to the biota in Rock Creek. 

References Cited 

Aalto, J.A., Jaworski, N.A., and Schremp, W.G., 1969, 

A water quality study of the Rock Creek Basin: 

Federal Water Pollution Control Admin., Middle Atlantic 

Region [unpublished study]. 

Agency for Toxic Substances and Disease Registry 

(ATSDR), 2001, Toxicological profile information 

sheets, U. S. Department of Health and Human Services, 

Public Health Service, accessed October 30, 2001, at 

http://www.atsdr.cdc.gov/toxprofiles 

Ator, S.W., Blomquist, J.D., Brakebill, J.W., Davis, J.M., 

Ferrari, M.J., Miller, C.V., and Zappia, Humbert, 

1998, Water quality in the Potomac River Basin, 

Maryland, Pennsylvania, Virginia, West Virginia, and the 

District of Columbia, 1992–96: U.S. Geological Survey 

Circular 1166, 38 p. 

Barbash, J.E., Resek, E.A., and Gilliom, R.J., 1997, 

Pesticides in ground water: Distribution, trends, and 

governing factors, pesticides in the hydrologic system, 

v. 2 (2nd ed.): Washington, D.C., Lewis Publishers, 

588 p. 

44 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Briggs, P.H., and Meier, A.L., 1999, The determination of 

forty-two elements in geological materials by Inductively 

Coupled Plasma—Mass Spectrometry: U.S. Geological 

Survey Open-File Report 99–166, 15 p. 

California Department of Pesticide Regulation, 2001, 

California product/label database queries and reports: 

Prepared for the California Environmental Protection 

Agency, Sacramento, California, acessed October 2001 

at http://www.cdpt.ca.gov/docs/label/labelque.htm 

Canadian Council of Ministers of the Environment, 1999, 

Canadian Water Quality Guidelines for the Protection 

of Aquatic Life—Summary table, in Canadian 

environmental quality guidelines, 1999: Winnipeg, 

Canada, Canadian Council of Ministers of the 

Environment, 5 p. 

CH2M Hill, 1977, Rock Creek storm water and water 

quality management study, prepared for the 

Montgomery County Planning Board: CH2M Hill, 

409 p. 

_____ 1979, Rock Creek Basin conservation study, prepared 

for the National Park Service: CH2M Hill, 366 p. 

Cloos, Ernst, and Cooke, C.W., 1953, Geologic map of 

Montgomery County and the District of Columbia: 

Maryland Department of Geology, Mines, and Water 

Resources, scale 1:62:500, 1 sheet. 

Darton, N.H., 1950, Configuration of the bedrock surface of 

the District of Columbia and vicinity: U.S. Geological 

Survey Professional Paper 217, 42 p. 

Daskalakis, K.D., and O’Conner, T.P., 1995, Normal 

ization and elemental sediment contamination in the 

coastal United States: Environmental Science and 

Technology, v. 29, p. 470–477. 

Dine, J.R., Adamski, J.C., and Duigon, M.T., 1995, 

Water resources of Howard County, Maryland: 

Maryland Geological Survey Bulletin 38, 128 p. 

Donnelly, C.A., and Ferrari, M.J., 1998, Summary 

of pesticide data from streams and wells in the 

Potomac River Basin, 1993–96: U.S. Geological Survey 

Open-File Report 97–666, 8 p. 

Duigon, M.T., Bolton, D.W., and Cooper, B.F., 2000, The 

influence of ground water on nitrate loads of streams 

in the upper Rock Creek Basin, Montgomery County, 

Maryland: Maryland Geological Survey Open-File 

Report 2000–02–13, 53 p. 

Extension Toxicology Network, 2001, Pesticide 

Information Profiles, accessed April 2001 at 

http://ace.ace.orst.edu/info/extoxnet. 

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

U.S. Geological Survey National Water-Quality 

Laboratory—Determination of inorganic and organic 

constituents in water and fluvial sediments: U.S. 

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

Fleming, A.H., Drake, A.A. Jr., and McCartan, Lucy, 

1994, Geologic map of the Washington West 

Quadrangle, District of Columbia, Montgomery and 

Prince Georges Counties, Maryland, and Arlington and

 Fairfax Counties, Virginia: U.S. Geological Survey 

Geologic Quadrangle Map GQ–1748, 1 sheet. 

Furlong, E.T., Vaught, D.G., Merten, L.M., Foreman, 

W.T., and Gates, P.M., 1996, Methods of analysis by 

the U.S. Geological Survey National Water-Quality 

Laboratory—Determination of semi-volatile organic 

compounds in bottom sediment by solvent extraction, 

gel permeation chromatographic fractionation, and 

capillary-column gas chromatography/mass 

spectrometry: U.S. Geological Survey Open-File Report 

95–719, 67 p. 

Hoffman, R.S., Capel, P.D., and Larson, S.J., 2000, 

Comparison of pesticides in eight U.S. urban streams: 

Environmental Toxicology and Chemistry, v. 19, no. 9, 

p. 2,249–2,258. 

International Joint Commission United States and 

Canada, 1989, Great Lakes Water Quality Agreement of 

1978, accessed August 2001 at http://www.ijc.org/agree/ 

quality/html 

James, R.W., Saffer, R.W., and Tallman, A.J., 2001, 

Water-resources data, Maryland and Delaware, 

Water Year 2000—Volume 1. Surface-water data: 

U.S. Geological Survey Water-Data Report

MD–DE–00–1, 418 p.

Larson, S.J., Capel, P.D., and Majewski, M.S., 1997, 

Pesticides in surface waters, pesticides in the hydrologic 

system: New York, Lewis Publishers, 866 p. 

Leopold, L.B., 1994, A view of the river: Cambridge, 

Massachusetts, Harvard University Press, 298 p. 

Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, 

Fluvial processes in geomorphology: San Francisco, 

California, W.H. Freeman and Company, 522 p. 

Long, E.R., and Morgan, L.G., 1990, The potential for 

biological effects of sediment-sorbed contaminants 

tested in the National Status and Trends Program, 

NOAA Technical Memorandum NOS OMA 52, 

National Oceanic and Atmospheric Administration, 

Seattle, Washington, accessed August 2001at 

http://www.dep.state.fl.us/dwm/documents/sediment/ 

default.htm 

MacDonald, D.D., 1994, 1994 Florida sediment quality 

assessment guidelines: Tallahassee, Florida, Report of 

the Florida Department of Environmental Protection, 

149 p. 

Maloney, T.J., Ludtke, A.S., and Krizman, T.L., 1994, 

Quality-assurance results for routine water analysis in 

U.S. Geological Survey Laboratories, Water Year 1991: 

U.S. Geological Survey Water-Resources Investigations 

Report 94–4046, 144 p. 

Maryland Department of Agriculture, 1993, Maryland 

pesticide statistics for 1991: Annapolis, Maryland, 

Maryland Department of Agriculture, 23 p. 

_____ 1996 Maryland pesticide statistics for 1994: 

Annapolis, Maryland, Maryland Department of 

Agriculture, 51 p. 

References Cited 45 
_____ 1999, Maryland pesticide statistics for 1997: 

Annapolis, Maryland, Maryland Department of 

Agriculture, 42 p. 

Maryland–National Capital Park and Planning 

Commission, 1999, Environmental resources 

inventory for the upper Rock Creek Basin: 

Silver Spring, Maryland, Maryland–National 

Capital Park and Planning Commission, 70 p. 

Montgomery County Department of Environmental 

Protection, March 17, 1997, Lower Rock Creek 

Basin study: Montgomery County Department of 

Environmental Protection, Basin Management 

Division, 10 p. 

National Oceanic and Atmospheric Administration, 

1999, Climatological data for Maryland and Delaware, 

National Environmental Satellite: Asheville, North 

Carolina, National Climatic Data Center, v. 103, 

nos. 10–12, ISSN 0145–0549, [variously paged]. 

_____ 2000, Climatological data for Maryland and 

Delaware, National Environmental Satellite: 

Asheville, North Carolina, National Climatic Data 

Center, v. 105, nos. 01–09, ISSN 0364–5843, 

[variously paged]. 

Nowell, L.H., Capel, P.D., and Dileanis, P.D., 1999, 

Pesticides in stream sediment and aquatic biota, 

pesticides in the hydrologic system: Chelsea, Michigan, 

Ann Arbor Press, 312 p. 

Nutter, L.J., and Otton, E.G., 1969, Ground-water 

occurrence in the Maryland Piedmont: Maryland 

Geological Survey Bulletin 34, 133 p. 

Patton, C.J., and Truitt, E.P., 1992, Methods of analysis 

by the U.S. Geological Survey National Water-Quality 

Laboratory—Determination of total phosphorus 

by a Kjeldahl digestion method and an automated 

colorimetric finish that includes dialysis: U.S. 

Geological Survey Open-File Report 92–146, 39 p. 

Patton, C.J., and Wade, A.P., 1997, Continuous flow 

analyzers, in Ewing, Galen (ed.), Analytical 

instrumentation handbook (2d ed.): New York, 

Marcel Dekker, p. 125–220. 

Pritt, J.W., and Raese, J.W. eds., 1995, Quality assurance/ 

quality control manual, National Water-Quality 

Laboratory: U.S. Geological Survey Open-File Report 

95–443, 35 p. 

Radtke, D.B., 1998, National field manual for collection 

of water-quality data—Bottom-material samples: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A8. [variously paged.] 

Rice, K.C., 1999, Trace-element concentrations in 

streambed sediment across the conterminous 

United States: Environmental Science and 

Technology, v. 33, no. 15, p. 2,499–2,504. 

Rosgen, D.L., 1994, A classification of natural rivers: 

Catena, v. 22, p. 169–199. 

_____ 1996, Applied river morphology, Pagosa Springs, 

Colorado: Wildland Hydrology, 363 p. 

Sherman, L.K., and Horner, W.W., 1935, Report on 

measure and elimination of pollution of Rock Creek 

and its tributaries in Washington, Federal Project 

Number 607: U.S. Department of the Interior, 

National Park Service, 74 p. 

Taylor, J.K., 1987, Quality assurance of chemical 

measurements: Chelsea, Michigan, Lewis Publishers, 

Inc., 328 p. 

U.S. Environmental Protection Agency, 1999, National 

recommended water-quality criteria-correction: 

Office of Water, Publication Number EPA 

822–Z–99–001, 25 p. 

_____ 2001, National primary drinking-water standards: 

Office of Water, Publication Number EPA 

816–F–01–007, 4 p. 

Vogelmann, J.E., Howard, S.M., Yang, Limin, Larson, 

C.R., Wylie, B.K., Van Driel, Nick, 2001, Completion 

of the 1990s National land cover data set for the 

conterminous United States from lands at thematic 

mapper data and ancillary data sources: 

Photogrammetric Engineering and Remote Sensing, 

v. 67, no. 6, p. 650–662. 

Werner, S.L., Burkhardt, M.R., and DeRusseau, S.N., 

1996, Methods of analysis by the U.S. Geological Survey 

National Water-Quality Laboratory: Determination 

of pesticides in water by Carbopak–B solid-phase 

extraction and high-performance liquid chromatography: 

U.S. Geological Survey Open-File Report 96–216, 42 p. 

Wilde, F.D., and Radtke, D.B., 1998, National field 

manual for collection of water-quality data—Field 

measurements: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chap. A6, no. 

[variously paged] 

Wilde, F.D., Radtke, D.B., Gibs, Jacob, and Iwatsubo, 

R.T., 1998, National field manual for collection of 

water-quality data—Collection of water samples: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A4, no. [variously paged] 

Yorke, T.H., and Herb, W.J., 1978, Effects of urbanization 

on streamflow and sediment transport in the 

Rock Creek and Anacostia River Basins, 

Montgomery County, Maryland, 1962–74: U.S. 

Geological Survey Professional Paper 1003, 71 p. 

Zaugg, S.D., Sandstrom, M.W., Smith, S.G., and 

Fehlberg, K.M., 1995, Methods of analysis by the 

U.S. Geological Survey National Water-Quality 

Laboratory: Determination of pesticides in water by 

C–18 solid-phase extraction and capillary-column gas 

chromatography/mass spectrometry with selected-ion 

monitoring: U.S. Geological Survey Open-File Report 

95–81, 60 p. 

46 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendixes A through C follow 

Appendixes 47 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C.

 [Filtered samples were filtered using a 0.7-micron Gelman filter. USGS, U.S. Geological Survey; μg/L, micrograms per liter;

 <, less than; α, alpha; E, estimated value less than the method reporting level; –, no data available] 

2,6–Diethyl­ 3–Hydroxy2,4,5–T, 1 2,4–D, 2 2,4–DB, 3 aniline, carbofuran, 

USGS water, water, water, water, water, 

station USGS dissolved dissolved dissolved dissolved dissolved 

number station name Date Time (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) 

SYNOPTIC SAMPLING 

1647998 Rock Creek below 06/23/1999 1800 <0.04 <0.15 <0.24 <0.003 <0.29 

West Beach Drive, 

Washington, D.C. 

1648004 Pinehurst Branch at 06/24/1999 1510 < .04 < .15 < .24 < .003 < .01 

Oregon Avenue, 

Washington, D.C. 

1648006 Rock Creek tributary 06/24/1999 1010 < .04 < .15 < .24 < .003 < .01 

 at Golf Course, 

Washington, D.C. 

1648010 Rock Creek at 06/25/1999 0930 < .04 < .15 < .24 < .003 < .06 

Joyce Road, 

Washington, D.C. 

1648998 Rock Creek 06/23/1999 1150 < .04 < .15 < .24 < .003 < .52 

Q Street, 

Washington, D.C. 

TEMPORAL SAMPLING 

1648010 Rock Creek at 02/18/1999 1115 <0.04 <0.40 <0.24 <0.003 <0.01 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 03/09/1999 1018 < .04 .10 < .24 < .003 < .01 

 Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 05/04/1999 1130 < .04 < .15 < .24 < .003 < .45 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 05/23/1999 0045 < .04 < .76 < .24 < .003 < .44 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 05/24/1999 1100 < .04 < .81 < .24 < .003 < .62 

Joyce Road, 

Washington, D.C. 

1. 2,4,5–Trichlorophenoxyacetic acid. 

2. (2,4–Dichlorophenoxy)acetic acid. 

3. 4–(2,4–Dichlorophenoxy)butyric acid. 

48 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

SYNOPTIC SAMPLING

TEMPORAL SAMPLING

Aldicarb Aldicarb 

Acetochlor, Acifluorfen, Alachlor, sulfone, sulfoxide, Aldicarb, α–HCH, 4 

water, water, water, water, water, water, water, USGS 

dissolved dissolved dissolved dissolved dissolved dissolved dissolved station 

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number 

<0.002 <0.04 <0.002 <0.38 <0.30 <3.17 <0.002 1647998 

< .002 < .04 < .002 < .10 < .02 < .55 < .002 1648004 

< .002 < .04 < .002 < .10 < .02 < .55 < .002 1648006 

< .002 < .04 < .002 < .10 < .02 < .55 < .002 1648010 

< .002 < .04 < .002 < .10 < .02 <4.47 < .002 1648998 

<0.002 <0.04 <0.002 <0 .10 <0.02 <0.55 <0.002 1648010 

< .002 < .04 < .002 < .10 < .02 < .55 < .002 1648010 

< .002 < .04 < .002 < .77 < .02 < .55 < .002 1648010 

< .002 < .04 < .002 < .88 < .02 < .55 < .002 1648010 

< .002 < .04 < .012 < .10 < .02 < .89 < .002 1648010 

4. α–1,2,3,4,5,6–Hexachlorocyclohexane. 

Appendixes 49 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

2,6–Diethyl­ 3–Hydroxy2,4,5–T, 1 2,4–D, 2 2,4–DB, 3 aniline, carbofuran, 

USGS water, water, water, water, water, 

station USGS dissolved dissolved dissolved dissolved dissolved 

number station name Date Time (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) 

TEMPORAL SAMPLING—Continued 

1648010 Rock Creek at 05/24/1999 1145 <0.04 <0.95 <0.24 <0.003 <0.24 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 07/14/1999 0920 < .04 < .15 < .24 < .003 < .69 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 10/13/1999 0930 < .04 < .11 < .10 < .003 < .13 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 01/10/2000 1430 < .04 < .32 < .10 < .003 < .11 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 02/09/2000 1300 < .04 < .26 < .10 < .003 < .11 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 03/21/2000 1200 < .04 < .39 < .10 < .003 < .17 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 05/16/2000 1145 < .04 < .11 < .10 < .003 < .16 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 06/22/2000 1000 < .04 < .73 < .10 < .003 < .11 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 07/26/2000 0900 < .04 < .34 < .16 < .003 <41.6 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 09/11/2000 1230 < .04 < .11 < .10 < .003 < .30 

Joyce Road, 

Washington, D.C. 

1648010 Rock Creek at 09/26/2000 0945 < .04 .55 < .10 < .003 < .11 

Joyce Road, 

Washington, D.C. 

50 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
TEMPORAL SAMPLING—Continued

Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

Aldicarb Aldicarb


Acetochlor, Acifluorfen, Alachlor, sulfone, sulfoxide, Aldicarb, α–HCH, 4


water, water, water, water, water, water, water, USGS


dissolved dissolved dissolved dissolved dissolved dissolved dissolved station


(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number


<0.002 <0.04 <0.014 <0.10 <0.02 <0.55 <0.002 1648010


< .002 < .04 < .002 < .10 < .02 < .55 < .002 1648010


< .002 < .09 < .002 <1.05 < .02 < .67 < .002 1648010


< .002 < .09 < .002 < .10 < .02 <1.66 < .002 1648010


< .002 < .09 < .002 < .10 < .18 < .21 < .002 1648010


< .002 < .09 < .002 < .10 < .02 <2.26 < .002 1648010


< .002 < .09 < .002 < .11 < .02 < .22 < .002 1648010


.013 < .09 < .002 < .27 < .15 < .38 < .002 1648010


< .002 < .09 < .002 <4.29 < .02 <12.1 < .002 1648010


< .002 < .09 < .002 < .10 < .45 < .21 < .002 1648010


< .002 < .09 < .002 < .30 < .33 < .23 < .002 1648010


Appendixes 51 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

Atrazine, Benfluralin, Bentazon, Bromacil, Bromoxynil, Butylate, 

USGS water, BDMC, 5 water, water, water, water, water, 

station dissolved surrogate dissolved dissolved dissolved dissolved dissolved 

number (μg/L) (percent) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 0.042 97 <0.002 <0.01 <0.44 <0.04 <0.002 

1648004 .011 88 < .003 < .01 < .04 < .04 < .002 

1648006 < .001 90 < .002 < .01 < .04 < .04 < .002 

1648010 .041 150 < .002 < .01 < .18 < .04 < .002 

1648998 .033 90 < .002 < .01 < .49 < .13 < .002 

TEMPORAL SAMPLING—Continued 

1648010 0.010 94 <0.002 <0.01 <0.40 <0.04 <0.002 

1648010 .017 E 131 < .002 < .01 < .04 < .04 < .002 

1648010 .023 56 < .002 < .01 < .13 < .04 < .002 

1648010 .058 73 < .002 < .01 <1.09 < .04 < .002 

1648010 .064 127 E .002 < .01 < .50 < .04 < .002 

1648010 .065 124 E .003 < .01 < .10 < .04 < .002 

1648010 .087 66 < .002 < .01 < .45 < .04 < .002 

1648010 .013 69 < .002 < .04 < .12 < .04 < .002 

1648010 .011 100 < .002 < .04 < .15 < .04 < .002 

1648010 .016 105 .002 < .04 < .21 < .04 < .002 

1648010 .010 85 .004 < .04 < .23 < .04 < .002 

1648010 .039 78 < .002 < .04 < .06 < .04 < .002 

1648010 .145 109 < .002 < .04 < .29 < .04 < .002 

1648010 .063 111 < .002 < .04 < .67 < .04 < .002 

1648010 .023 91 < .002 < .04 < .19 < .04 < .002 

1648010 < .001 127 < .002 < .04 < .06 < .04 < .002 

5. 4–Bromo–3,5–dimethylphenyl–n–methylcarbamate. 

52 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

SYNOPTIC SAMPLING

TEMPORAL SAMPLING

Carbaryl, Carbaryl, Carbofuran, Carbofuran, Chloramben, 

water, water, water, water, methyl ester, Chlorothalonil, Chlorpyrifos, 

dissolved dissolved dissolved dissolved water, water, water, USGS 

(μg/L) (μg/L) (μg/L) (μg/L) dissolved dissolved dissolved station 

(2050) 6 (2001) 6 (2050) 6 (2001) 6 (μg/L) (μg/L) (μg/L) number 

<0.01 E 0.029 <0.12 <0.003 – <0.48 0.004 1647998

 .05 E .088 < .12 < .003 – < .48 E .003 1648004 

< .01 < .003 < .12 < .003 – < .48 < .004 1648006 

< .01 E .10 < .12 < .003 – < .48 .004 1648010 

< .01 E .049 < .12 < .003 – < .48 < .004 1648998 

<0.01 <0.003 <0.26 <0.003 – <0.48 0.017 1648010 

< .01 < .003 < .12 < .003 – < .48 < .004 1648010 

< .01 E .008 < .12 < .003 – < .48 E .003 1648010 

< .01 E .041 < .12 < .003 – < .48 < .004 1648010

 .12 E .17 < .12 < .003 – < .48 < .017 1648010

 .24 E .41 < .12 < .003 – < .48 < .020 1648010 

E .03 E .14 < .12 < .003 – < .48 .009 1648010 

< .07 E .015 < .29 < .003 – < .48 .006 1648010 

< .07 E .055 < .29 < .003 <0.14 < .48 .017 1648010 

< .07 E .012 < .29 < .003 < .14 < .48 E .008 1648010 

< .07 E .042 < .29 < .003 < .14 < .48 < .004 1648010 

< .07 E .007 < .29 < .003 < .14 < .48 .005 1648010

 1.14 E 1.7 < .29 < .003 < .14 < .48 .010 1648010

 .34 E .52 < .29 < .006 < .14 < .48 < .004 1648010 

< .07 E .009 < .29 < .003 < .14 < .48 E .003 1648010

 .12 E .22 < .29 < .003 < .14 < .48 .007 1648010 

6. U.S. Geological Survey National Water-Quality Laboratory analytical schedule numbers. 

Appendixes 53 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

USGS 

station 

number 

Cyanazine, 

water, 

dissolved 

(μg/L) 

Dacthal 

monoacid, 

dissolved 

(μg/L) 

Dacthal, 

dissolved 

(μg/L) 

Desethylatrazine, 

water, 

dissolved 

(μg/L) 

Diazinon–d10, 

surrogate, 

(percent) 

Diazinon, 

water, 

dissolved 

(μg/L) 

Dicamba, 

water, 

dissolved 

(μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.02 

< .02 

< .02 

< .02 

< .02 

<0.002 

< .002 

< .002 

< .002 

< .002 

E 0.043 

E .006 

< .002 

E .070 

E .021 

99 

74 

112 

104 

105 

0.063 

.036 

< .002 

.038 

.083 

<0.04 

< .04 

< .04 

< .04 

< .04 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010

1648010

<0.004 

< .004 

< .004 

 .008 

 .009 

<0.02 

< .02 

< .02 

< .02 

< .02 

<0.002 

< .002 

< .002 

< .002 

< .002 

E 0.010 

E .043 

E .084 

E .064 

E .030 

91 

92 

98 

105 

101 

0.007 

E .003 

.006 

.120 

.152 

<0.04 

< .04 

< .04 

< .04 

< .04 

1648010 

1648010 

1648010 

1648010 

1648010 

< .004 

< .004 

< .004 

< .004 

< .004 

< .13 

< .02 

< .04 

< .04 

< .04 

< .002 

< .002 

< .002 

< .002 

E .002 

E .044 

E .063 

E .038 

E .034 

E .058 

94 

134 

120 

120 

106 

.127 

.028 

.060 

.019 

.011 

< .04 

< .04 

< .10 

< .04 

< .04 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

< .004 

< .007 

< .004 

< .004 

< .004 

< .004 

< .04 

< .04 

< .04 

< .04 

< .04 

< .04 

< .002 

< .002 

< .002 

< .002 

< .002 

< .002 

E .033 

E .062 

E .023 

E .029 

E .058 

E .012 

97 

87 

113 

120 

114 

109 

.054 

.028 

.307 

.079 

.035 

.106 

< .67 

< .04 

< .04 

< .29 

< .04 

< .04 

54 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

SYNOPTIC SAMPLING

TEMPORAL SAMPLING

Dichlobenil, Dichlorprop, Dieldrin, Dinoseb, Disulfoton, Diuron, DNOC, 7 

water, water, water, water, water, water, water, USGS 

dissolved dissolved dissolved dissolved dissolved dissolved dissolved station 

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number 

<1.20 <0.03 <0.001 <0.04 <0.017 <0.17 < 0.42 1647998 

<1.20 < .03 .006 < .04 < .017 < .02 < .42 1648004 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648006 

<1.20 < .03 < .001 < .04 < .017 .04 < .42 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648998 

<1.20 <0.53 <0.001 <0.04 <0.017 <0.02 E 0.33 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648010 

<1.20 < .11 < .001 < .04 < .017 < .02 < .42 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648010 

<1.20 < .03 < .001 < .04 < .017 < .02 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 < .06 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 < .06 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 < .06 < .42 1648010 

< .07 < .12 < .001 < .06 < .017 < .06 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 E .03 < .42 1648010 

< .07 < .17 < .001 < .06 < .017 < .06 < .42 1648010 

< .92 <2.08 < .001 < .06 < .017 < .18 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 < .06 < .42 1648010 

< .07 < .03 < .001 < .06 < .017 < .06 < .42 1648010 

7. 4,6–Dinitro–o–cresol. 

Appendixes 55 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C.— 

—Continued 

USGS 

station 

number 

EPTC, 8 

water, 

dissolved 

(μg/L) 

Ethalfluralin, 

water, 

dissolved 

(μg/L) 

Ethoprop, 

water, 

dissolved 

(μg/L) 

Fenuron, 

water, 

dissolved 

(μg/L) 

Fluometuron, 

water, 

dissolved 

(μg/L) 

Fonofos, 

water, 

dissolved 

(μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

<0.002 

< .002 

< .002 

< .002 

< .002 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.003 

< .003 

< .003 

< .003 

< .003 

<0.10 

< .01 

< .01 

< .01 

< .11 

<0.04 

< .04 

< .04 

< .04 

< .04 

<0.003 

< .003 

< .003 

< .003 

< .003 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

<0.002 

< .002 

< .002 

< .006 

< .018 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.003 

< .003 

< .003 

< .003 

< .003 

<0.01 

< .01 

< .01 

< .01 

<3.40 

<0.37 

< .04 

< .04 

< .04 

< .04 

<0.003 

< .003 

< .003 

< .003 

< .003 

1648010 

1648010 

1648010 

1648010 

1648010 

< .010 

< .002 

< .002 

< .002 

< .002 

< .004 

< .004 

< .004 

< .004 

< .004 

< .003 

< .003 

< .003 

< .003 

< .003 

<2.44 

< .01 

< .07 

< .07 

< .07 

< .04 

< .04 

< .06 

< .19 

< .06 

< .003 

< .003 

< .003 

< .003 

< .003 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

< .002 

< .002 

< .002 

< .002 

< .002 

< .002 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .003 

< .003 

< .003 

< .003 

< .003 

< .003 

< .07 

< .07 

< .07 

< .29 

< .07 

< .07 

< .06 

< .06 

< .10 

< .06 

< .06 

< .27 

< .003 

< .003 

< .003 

< .003 

< .003 

< .003 

8. s–Ethyl dipropylthiocarbamate. 

56 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

SYNOPTIC SAMPLING

TEMPORAL SAMPLING

Linuron, Linuron, 

Lindane, water, water, Malathion, MCPA, 10 MCPB, 11 

α–HCH–d6, 9 water, dissolved dissolved water, water, water, USGS 

surrogate dissolved (μg/L) (μg/L) dissolved dissolved dissolved station 

(percent) (μg/L) (2050) 6 (2001) 6 (μg/L) (μg/L) (μg/L) number 

101 <0.004 <0.02 <0.002 <0.005 <0.17 <0.14 1647998 

115 < .004 < .02 < .002 < .005 < .17 < .14 1648004 

88 < .004 < .02 < .002 < .005 < .17 < .14 1648006 

91 < .004 < .02 < .002 < .005 < .17 < .14 1648010 

105 < .004 < .02 < .002 < .005 < .17 < .14 1648998 

85 <0.004 <0.02 <0.002 <0.025 <0.17 <0.14 1648010 

70 < .004 < .02 < .002 < .005 < .17 < .14 1648010 

98 < .004 < .02 < .002 < .005 < .17 < .14 1648010 

97 < .004 < .02 < .002 < .005 < .17 < .14 1648010 

84 < .004 < .18 < .002 .020 < .17 < .14 1648010 

79 < .004 < .02 < .002 .031 < .17 < .14 1648010 

94 < .004 < .02 < .002 < .005 < .17 < .14 1648010 

110 < .004 < .09 < .002 < .005 < .17 < .13 1648010 

108 < .004 < .09 < .002 < .005 < .17 < .13 1648010 

97 < .004 < .09 < .002 < .005 < .17 < .13 1648010 

78 < .004 < .09 < .002 .014 < .17 < .13 1648010 

79 < .004 < .09 < .002 < .005 < .17 < .13 1648010 

96 < .004 < .09 < .002 .010 E .10 < .13 1648010 

106 < .004 < .09 < .002 .274 < .17 < .13 1648010 

108 < .004 < .09 < .002 < .005 < .17 < .13 1648010 

108 < .004 < .11 < .002 .006 < .17 < .13 1648010

 9. α–1,2,3,4,5,6–Hexachlorocyclohexane–d6.

 10. 4–(4–Chloro–2–methylphenoxy)acetic acid.

 11 4–(4–Chloro–2–methylphenoxy)butanoic acid. 

Appendixes 57 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

USGS 

station 

number 

Methiocarb, 

water, 

dissolved 

(μg/L) 

Methomyl, 

water, 

dissolved 

(μg/L) 

Methylazinphos, 

water, 

dissolved 

(μg/L) 

Methylparathion, 

water, 

dissolved 

(μg/L) 

Metolachlor, 

water, 

dissolved 

(μg/L) 

Metribuzin, 

water, 

dissolved 

(μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

<0.03 

< .03 

< .03 

< .03 

< .03 

<0.64 

< .02 

< .02 

< .02 

< .39 

<0.001 

< .001 

< .001 

< .001 

< .001 

<0.006 

< .006 

< .006 

< .006 

< .006 

0.020 

.007 

< .002 

.019 

.020 

<0.004 

< .004 

< .004 

< .004 

< .004 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

<0.03 

< .03 

< .03 

< .03 

< .03 

<0.02 

< .02 

< .12 

<1.06 

<1.13 

<0.001 

< .001 

< .001 

< .019 

< .028 

<0.006 

< .006 

< .006 

< .006 

< .006 

0.018 

.013 

.014 

.032 

.058 

<0.004 

< .004 

< .004 

< .004 

< .004 

1648010 

1648010 

1648010 

1648010 

1648010 

< .03

< .03 

< .03 

< .03 

< .03 

< .40 

< .87

< .28 

<1.01 

< .02 

< .025 

< .001 

< .001 

< .001 

< .001 

< .006 

< .006 

< .006 

< .006 

< .006 

.060 

.033 

.012 

.008 

.013 

< .004 

< .004 

< .004 

< .020 

< .015 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

< .03 

< .03 

< .03 

< .03 

< .03 

< .23 

< .72 

< .62 

<1.70 

< .02 

< .16 

< .55 

< .020 

< .010 

< .001 

< .001 

< .001 

< .001 

< .006 

< .006 

< .006 

< .006 

< .006 

< .006 

.010 

.031 

.115 

.030 

.014 

.014 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

58 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

Molinate, Napropamide, Neburon, Norflurazon, Oryzalin, Oxamyl, p,p’–DDE, 12 

water, water, water, water, water, water, water, USGS 

dissolved dissolved dissolved dissolved dissolved dissolved dissolved station 

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number 

<0.004 <0.003 <0.01 <0.02 <0.31 <0.02 <0.006 1647998 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648004 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648006 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648010 

< .004 < .003 < .01 < .02 < .43 < .02 < .006 1648998 

<0.004 <0.003 <0.01 <0.02 <0.31 <0.02 <0.006 1648010 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648010 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648010 

< .004 < .003 < .01 < .02 < .31 < .02 < .006 1648010 

< .004 .033 < .16 < .02 < .31 < .59 < .006 1648010 

< .004 – < .22 < .02 < .40 < .02 < .006 1648010 

< .004 < .003 < .01 < .02 < .46 < .02 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .08 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .28 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .02 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .62 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .02 < .006 1648010 

< .004 < .003 < .10 < .04 < .31 < .34 < .006 1648010 

< .004 < .003 < .30 < .04 < .31 < .02 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .37 < .006 1648010 

< .004 < .003 < .07 < .04 < .31 < .56 < .006 1648010 

12.

 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

Appendixes 59 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

USGS 

station 

number 

Parathion, 

water, 

dissolved 

(μg/L) 

Pebulate, 

water, 

dissolved 

(μg/L) 

Pendimethalin, 

water, 

dissolved 

(μg/L) 

cis–Permethrin, 

water, 

dissolved 

(μg/L) 

Phorate, 

water, 

dissolved 

(μg/L) 

Picloram, 

water, 

dissolved 

(μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.004 

E .012 

< .004 

< .004 

< .004 

<0.005 

< .005 

< .005 

< .005 

< .005 

<0.002 

< .002 

< .002 

< .002 

< .002 

<0.05 

< .05 

< .05 

< .05 

< .05 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.004 

< .004 

< .004 

< .004 

< .004 

<0.004 

< .004 

< .004 

< .004 

< .019 

<0.005 

< .005 

< .005 

< .005 

< .005 

<0.002 

< .002 

< .002 

< .002 

< .002 

<0.05 

< .05 

< .05 

< .37 

< .18 

1648010 

1648010 

1648010 

1648010 

1648010 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004

< .004 

< .004 

< .004 

< .004 

< .018 

< .004 

< .004 

< .004 

< .004 

< .005 

< .005 

< .005 

< .005 

< .005 

< .002 

< .002 

< .002 

< .002 

< .002 

< .05 

< .05 

< .05 

< .05 

< .05 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

< .004 

.036 

< .010 

.027 

< .010 

< .004 

< .004 

< .005 

< .005 

< .005 

< .005 

< .005 

< .005 

< .002 

< .002 

< .002 

< .002 

< .002 

< .002 

< .05 

< .13 

< .05 

< .05 

< .05 

< .05 

60 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected

in June 1999 and temporal water-quality samples collected from February 18, 1999,

through September 26, 2000, in surface water in Rock Creek, Washington, D.C.

—Continued

Prometon, Propyzamide, Propachlor, Propanil, Propargite, Propham, 

water, water, water, water, water, water, USGS 

dissolved dissolved dissolved dissolved dissolved dissolved station 

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number 

0.022 <0.003 <0.007 <0.004 <0.013 <0.11 1647998 

E .007 < .003 < .007 < .004 < .013 < .10 1648004 

< .018 < .003 < .007 < .004 < .013 < .04 1648006 

.018 < .003 < .007 < .004 < .013 < .04 1648010 

.029 < .003 < .007 < .004 < .013 < .13 1648998 

E 0.005 <0.003 <0.007 <0.004 <0.013 <0.04 1648010 

E 	 .004 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .004 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .009 < .003 < .007 < .004 < .013 < .15 1648010 

.022 < .003 < .007 < .004 < .013 < .92 1648010 

.032 < .003 < .007 < .004 < .013 < .20 1648010 

.029 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .011 < .003 < .007 < .004 < .013 < .12 1648010 

E 	 .009 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .011 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .005 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .011 < .003 < .007 < .004 < .013 < .04 1648010 

.058 < .020 < .007 < .004 < .013 < .66 1648010 

.072 < .020 < .007 < .004 < .013 < .31 1648010 

E 	 .013 < .003 < .007 < .004 < .013 < .04 1648010 

E 	 .012 < .003 < .007 < .004 < .013 < .04 1648010 

Appendixes 61 
Appendix A1. Results of analyses for dissolved pesticides for synoptic water-quality samples collected 

in June 1999, and temporal water-quality samples collected from February 18, 1999 

through September 26, 2000 in surface water in Rock Creek, Washington, D.C. 

—Continued 

USGS 

station 

number 

Propoxur, 

water, 

dissolved 

(μg/L) 

Silvex, 

water, 

dissolved 

(μg/L) 

Simazine, 

water, 

dissolved 

(μg/L) 

Tebuthiuron, 

water, 

dissolved 

(μg/L) 

Terbacil, 

water, 

dissolved 

(μg/L) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

<0.04 

< .04 

< .04 

< .04 

< .13 

<0.02 

< .02 

< .02 

< .02 

< .02 

0.038 

.007 

< .005 

.034 

.046 

<0.010 

< .010 

< .010 

< .010 

< .010 

<0.007 

< .007 

< .007 

< .007 

< .007 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

<0.11 

< .04 

< .04 

< .98 

< .55 

<0.02 

< .02 

< .02 

< .02 

< .02 

0.009 

.009 

.009 

.021 

.021 

<0.010 

E .006 

.010 

< .016 

< .010 

<0.007 

< .007 

< .007 

< .007 

< .007 

1648010 

1648010 

1648010 

1648010 

1648010 

< .04 

< .04 

< .08 

< .08 

< .08 

< .02 

< .02 

< .06 

< .06 

< .06 

.022 

.083 

.010 

< .005 

.020 

< .010 

< .010 

E .006 

< .010 

< .010 

< .007 

< .007 

< .007 

< .007 

< .007 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

< .08 

< .08 

< .29 

< .19 

< .37 

< .18 

< .06 

< .06 

< .06 

< .06 

< .06 

< .06 

.008 

.016 

.012 

.010 

.014 

.018 

< .010 

< .010 

< .010 

< .010 

E .004 

< .010 

< .007 

< .007 

< .007 

< .007 

< .007 

< .007 

62 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A1. Results of analyses for dissolved pesticides analyses for synoptic water-quality samples

in June 1999 and temporal sampling from February 18, 1999 through 

September 26, 2000 in surface water in Rock Creek Park, Washington, D.C., in

August 1999—Continued

Terbufos, Thiobencarb, Triallate, Triclopyr, Trifluralin, 

water, water, water, water, water, USGS 

dissolved dissolved dissolved dissolved dissolved station 

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) number 

<0.013 <0.002 <0.001 <0.25 <0.002 1647998 

< .013 < .002 < .001 < .25 E .003 1648004 

< .013 < .002 < .001 < .25 < .002 1648006 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648998 

<0.013 <0.002 <0.001 <0.25 <0.002 1648010 

< .013 < .002 < .001 < .25 E .002 1648010 

< .013 < .002 < .001 < .25 E .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 E .003 1648010 

< .013 < .002 < .001 < .25 E .003 1648010 

< .013 < .002 < .001 < .67 < .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 .006 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 < .25 E .002 1648010 

< .013 < .002 < .001 < .25 < .002 1648010 

< .013 < .002 < .001 .26 < .002 1648010 

< .013 < .002 < .001 E .23 < .002 1648010 

Appendixes 63 
Appendix A2. Results of analyses for nutrients, major ions, and field parameters for

 synoptic sampling in June 1999, and temporal sampling from 

February 18, 1999 through September 26, 2000 in surface water 

from Rock Creek, Washington, D.C.

 [USGS, U.S. Geological Survey; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; 

μg/L, micrograms per liter; mm, millimeters; ft

3/s, cubic feet per second; E, estimated value lower than the reporting level;

 –, missing value; “Nitrogen, ammonia plus organic nitrogen” is also known as “Kjeldahl nitrogen.”] 

USGS Instantaneous 

station USGS discharge 

number station name Date Time (ft3/s) 

SYNOPTIC SAMPLING 

1647998 Rock Creek below West Beach Drive, Washington, D.C. 06/23/1999 1800 18 

1648004 Pinehurst Branch at Oregon Avenue, Washington, D.C. 06/24/1999 1510 .07 

1648006 Rock Creek tributary at Golf Course, Washington, D.C. 06/24/1999 1010 .01 

1648010 Rock Creek at Joyce Road, Washington, D.C. 06/25/1999 0930 11 

1648998 Rock Creek Q Street, Washington, D.C. 06/23/1999 1150 21 

TEMPORAL SAMPLING 

1648010 Rock Creek at Joyce Road, Washington, D.C. 02/18/1999 1115 415 

1648010 Rock Creek at Joyce Road, Washington, D.C. 03/09/1999 1018 39 

1648010 Rock Creek at Joyce Road, Washington, D.C. 05/04/1999 1130 24 

1648010 Rock Creek at Joyce Road, Washington, D.C 05/23/1999 0045 103 

1648010 Rock Creek at Joyce Road, Washington, D.C. 05/24/1999 1100 430 

1648010 Rock Creek at Joyce Road, Washington, D.C. 05/24/1999 1145 480 

1648010 Rock Creek at Joyce Road, Washington, D.C. 07/14/1999 0920 6.1 

1648010 Rock Creek at Joyce Road, Washington, D.C. 10/13/1999 0930 35 

1648010 Rock Creek at Joyce Road, Washington, D.C. 01/10/2000 1430 276 

1648010 Rock Creek at Joyce Road, Washington, D.C. 02/09/2000 1300 32 

1648010 Rock Creek at Joyce Road, Washington, D.C. 03/21/2000 1200 402 

1648010 Rock Creek at Joyce Road, Washington, D.C. 05/16/2000 1145 24 

1648010 Rock Creek at Joyce Road, Washington, D.C. 06/22/2000 1000 149 

1648010 Rock Creek at Joyce Road, Washington, D.C. 07/26/2000 0900 124 

1648010 Rock Creek at Joyce Road, Washington, D.C. 09/11/2000 1230 13 

1648010 Rock Creek at Joyce Road, Washington, D.C. 09/26/2000 0945 364 

64 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A2. Results of analyses for nutrients, major ions, and field paramaters for

 synoptic sampling in June 1999 and temporal sampling from 

February 18, 1999 through September 26, 2000 in surface water 

in Rock Creek, Washington, D.C.

 [USGS, U.S. Geological Survey; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; deg C., degrees in Centigrade;

μg/L, micrograms per liter; mm, millimeters; ft

3/s, cubic feet per second; E, estimated value lower than the reporting level;

 –, missing value]

SYNOPTIC SAMPLING

TEMPORAL SAMPLING

Oxygen, pH, Specific Air Water USGS 

dissolved field conductance temperature temperature station 

(mg/L) (standard units) (μS/cm) ( ° C) ( ° C) number 

7.2 7.9 367 23.5 21.7 1647998 

4.3 7.5 503 22.7 19.6 1648004 

8.3 7.3 92 18.9 15.7 1648006 

7.3 7.8 381 23.7 20.9 1648010 

8.3 7.8 289 26.0 20.4 1648998 

10.7 7.5 268 5.5 7.4 1648010 

12.4 7.0 380 -3.0 2.6 1648010 

9.8 8.1 402 17.5 13.9 1648010 

9.2 6.9 382 17.0 19.5 1648010 

6.8 7.0 207 21.0 19.1 1648010 

5.5 7.0 232 21.0 19.6 1648010 

8.4 7.6 481 19.0 20.9 1648010 

10.3 7.8 227 10.5 14.3 1648010 

11.6 6.1 197 9.0 6.8 1648010 

15.6 7.7 1,380 12.5 0.1 1648010 

12.2 7.4 247 5.5 7.3 1648010 

9.3 7.9 340 21.0 17.3 1648010 

6.1 7.2 118 24.4 23.3 1648010 

– 7.4 229 22.7 20.5 1648010 

8.9 7.9 292 25.5 28.8 1648010 

9.2 7.2 115 11.0 14.2 1648010 

Appendixes 65 
Appendix A2. Results of analyses for nutrients, major ions, and field parameters for

 synoptic sampling in June 1999, and temporal sampling from 

February 18, 1999 through September 26, 2000 in surface water 

from Rock Creek, Washington, D.C.—Continued 

USGS 

station 

number 

Calcium, 

dissolved 

(mg/L 

as Ca) 

Magnesium, 

dissolved 

(mg/L 

as Mg) 

Potassium, 

dissolved 

(mg/L 

as K) 

Sodium, 

dissolved 

(mg/L 

as Na) 

Chloride, 

dissolved 

(mg/L 

as Cl) 

Fluoride, 

dissolved 

(mg/L 

as F) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

28.3 

45.8 

7.98 

29.4 

24.7 

9.58 

15.2 

2.36 

10.1 

7.57 

3.3 

4.3 

1.7 

3.4 

3.7 

24.8 

22.5 

5.1 

24.6 

16.4 

56.3 

62.5 

4.2 

57.2 

33.8 

0.2 

0.1 

<0.1 

0.3 

0.2 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

66 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A2. Results of analyses for nutrients, major ions, and field paramaters for

 synoptic sampling in June 1999 and temporal sampling from

February 18, 1999 through September 26, 2000 in surface water

in Rock Creek, Washington, D.C.—Continued

SYNOPTIC SAMPLING—Continued

TEMPORAL SAMPLING—Continued

Nitrogen, Nitrogen, 

Silica, Sulfate, ammonia ammonia Nitrogen, 

dissolved dissolved plus organic plus organic ammonia, USGS 

(mg/L (mg/L nitrogen, dissolved nitrogen, total dissolved station 

as SiO2 ) as SO4 ) (mg/L as N) (mg/L as N) (mg/L as N) number 

10.2 18.4 0.38 0.39 0.066 1647998 

23.4 32.9 .28 .32 .044 1648004 

16.6 2.7 E .10 .11 < .020 1648006 

10.7 18.4 .37 .35 .053 1648010 

8.4 16.9 .28 .33 .037 1648998 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

Appendixes 67 
Appendix A2. Results of analyses for nutrients, major ions, and field parameters for

 synoptic sampling in June 1999, and temporal sampling from 

February 18, 1999 through September 26, 2000 in surface water 

from Rock Creek, Washington, D.C.—Continued 

USGS 

station 

number 

Nitrogen, 

nitrate plus 

nitrite, 

dissolved 

(mg/L as N) 

Nitrogen, 

nitrite, 

dissolved 

(mg/L 

as N) 

Phosphorus, 

dissolved 

(mg/L 

as P) 

Phosphorus, 

phosphate, 

ortho, dissolved 

(mg/L 

as P) 

Phosphorus, 

total, 

(mg/L 

as P) 

SYNOPTIC SAMPLING—Continued 

1647998 

1648004 

1648006 

1648010 

1648998 

0.611 

.584 

1.54 

.633 

.531 

0.022 

.014 

< .010 

.022 

.016 

0.025 

.085 

.021 

.020 

.031 

0.023 

.064 

.023 

.021 

.025 

0.058 

.100 

.024 

.047 

.044 

TEMPORAL SAMPLING—Continued 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

1648010 

1648010 

1648010 

1648010 

1648010 

1648010 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

– 

68 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A2. Results of analyses for nutrients, major ions, and field paramaters for

 synoptic sampling in June 1999 and temporal sampling from

February 18, 1999 through September 26, 2000 in surface water

in Rock Creek, Washington, D.C.—Continued

SYNOPTIC SAMPLING—Continued

TEMPORAL SAMPLING—Continued

Residue, 

180 degrees Iron, Manganese, Sediment, 

Celsius, dissolved dissolved Sediment, suspended, USGS 

dissolved (μg/L (μg/L suspended percent finer station 

(mg/L) as Fe) as Mn) (mg/L) than .062 mm number 

258 180 104 – – 1647998 

312 10 56 – – 1648004 

103 20 E 2 – – 1648006 

235 70 104 – – 1648010 

193 130 53 – – 1648998 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – – – 1648010 

– – – 15 – 1648010 

– – – 6 – 1648010 

– – – 149 76 1648010 

– – – 6 – 1648010 

– – – 305 – 1648010 

– – – 17 – 1648010 

– – – 128 – 1648010 

– – – 38 – 1648010 

– – – 15 – 1648010 

– – – 314 77 1648010 

Appendixes 69 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment 

collected from Rock Creek, Washington, D.C., August 1999 

[All samples are bottom material, whole sediment sieved to less than 2 millimeters, dry weight. Recoveries of surrogate

 compounds (given by percent) from the analyses are included in the results; g/kg, grams per kilogram; μg/kg, micrograms per

 kilogram; <, less than; E, estimated value less than the method reporting level; M, presence of material verified but not 

quantified; α, alpha; β, beta] 

Station 

number Station name Date Time 

Carbon, organic 

plus inorganic 

(g/kg as C) 

01647997 Portal Branch at North Portal Drive,

 Washington, D.C. 

08/19/1999 1130 5.7 

01648000 Rock Creek at Sherrill Drive, 

Washington, D.C. 

08/18/1999 1400 24 

01648998 Rock Creek Q Street,

 Washington, D.C. 

08/17/1999 1115 27 

Station 

number 

2,2 ́–Biquinoline 

(μg/kg) 

3,5–Xylenol 

(μg/kg) 

4–Bromophenyl 

phenyl ether 

(μg/kg) 

4–Chlorophenyl 

phenyl ether 

(μg/kg) 

01647997 <50 <50 <50 <50 

01648000 <50 <50 <50 <50 

01648998 <100 <100 <100 <100 

Station 4,5–Methylenephenanthrene Anthraquinone 1–Methyl–9H–fluorene Fluorene 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 E 20 100 <50 M 

01648000 130 380 <50 E 30 

01648998 120 280 <100 E 40 

70 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A3. Results of analyses for organic compounds measured in samples of 

bed sediment collected from Rock Creek, Washington, D.C., August 1999

 [All samples are bottom material, whole sediment, less than 2 millimeters, distilled water recovered. Recoveries of surrogate

 compounds (given by percent) from the analyses are included in the results; g/kg, grams per kilogram; μg/kg, micrograms per

 kilogram; <, less than; E, estimated value less than the method reporting level; M, presence of material verified but not

quantified; α, alpha; β, beta]

Acenaphthene 

(μg/kg) 

<50 

Acenaphthylene 

(μg/kg) 

E 40 

Acridine 

(μg/kg) 

<50 

Aldrin 

(μg/kg) 

<1 

Station 

number 

01647997 

E 10 70 60 <1 01648000 

E 30 E 60 E 40 <1 01648998 

α−HCH–d6 

(surrogate, α–HCH 2–Methylanthracene Anthracene Station 

percent) (μg/kg) (μg/kg) (μg/kg) number 

74 <1 E 10 60 01647997 

57 <1 E 20 160 01648000 

57 <1 E 20 190 01648998 

Azobenzene Benz(a)anthracene 1,2,4–Trichlorobenzene Hexachlorobenzene Station 

(μg/kg) (μg/kg) (μg/kg) (μg/kg) number 

<50 210 <50 <1 01647997 

<50 690 <50 <1 01648000 

<100 660 <100 <1 01648998 

Appendixes 71 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment 

collected from Rock Creek, Washington, D.C., August 1999—Continued 

Nitrobenzene–d5 

Station m–Dichlorobenzene Nitrobenzene (surrogate, o–Dichlorobenzene 

number (μg/kg) (μg/kg) percent) (μg/kg) 

01647997 <50 <50 43 <50 

01648000 <50 <50 67 <50 

01648998 <100 <100 51 <100 

Station p–Dichlorobenzene Pentachloronitrobenzene Benzo[a]pyrene Benzo[b]fluoranthene 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 <50 <50 240 270 

01648000 <50 <50 880 1,300 

01648998 <100 <100 810 1,200 

Station Benzo[ghi]perylene Benzo[k]fluoranthene Benzo[c]cinnoline β–HCH 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 140 160 <50 <1 

01648000 640 820 <50 <1 

01648998 420 880 <50 <1 

72 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment

collected from Rock Creek, Washington, D.C., August 1999—Continued

2–Fluorobiphenyl 

(surrogate, 

percent) 

Bis(2–chloroethyl)ether 

(μg/kg) 

Carbazole 

(μg/kg) 

Chloroneb 

(μg/kg) 

Station 

number 

51 <50 E 10 <5 01647997 

67 <50 130 <5 01648000 

52 <100 110 <5 01648998 

Chrysene 

(μg/kg) 

cis–Chlordane 

(μg/kg) 

cis–Nonachlor 

(μg/kg) 

cis–Permethrin 

(μg/kg) 

Station 

number

 260 2 <1 <5 01647997 

1,200 7 2 <5 01648000 

1,000 7 2 <5 01648998 

Dacthal Dibenz[ah]anthracene Dieldrin N–Nitrosodi-n-propylamine Station 

(μg/kg) (μg/kg) (μg/kg) (μg/kg) number 

<5 E 40 2 <50 01647997 

<5 140 3 <50 01648000 

<5 210 3 <100 01648998 

Appendixes 73 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment 

collected from Rock Creek, Washington, D.C., August 1999—Continued 

Station N–Nitrosodiphenylamine Endosulfan Endrin Fluoranthene 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 <50 <1 <2 500 

01648000 <50 <1 <2 2,000 

01648998 <100 <1 <2 1,600 

Station Heptachlor epoxide Heptachlor Indeno[1,2,3–cd]pyrene Isodrin 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 <1 <1 180 <1 

01648000 2 <1 750 <1 

01648998 2 <1 550 <1 

Station 

number 

Isophorone 

(μg/kg) 

Isoquinoline 

(μg/kg) 

Lindane 

(μg/kg) 

4–Chloro–3–methylphenol 

(μg/kg) 

01647997 <50 <50 <1 <50 

01648000 <50 <50 <1 <50 

01648998 <100 <100 <1 <100 

74 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment

collected from Rock Creek, Washington, D.C., August 1999—Continued

Bis(2–chloroethoxy) 

methane 

(μg/kg) 

o,p ́–Methoxychlor 

(μg/kg) 

p,p ́–Methoxychlor 

(μg/kg) 

Mirex 

(μg/kg) 

Station 

number 

<50 <5 <5 <1 01647997 

<50 <6 <5 <1 01648000 

<100 <5 <5 <1 01648998 

1,2–Dimethylnaphthalene 

(μg/kg) 

1,6–Dimethylnaphthalene 

(μg/kg) 

2,3,6–Trimethylnaphthalene 

(μg/kg) 

2,6–Dimethylnaphthalene 

(μg/kg) 

Station 

number 

<50 <50 <50 <50 01647997 

<50 <50 <50 E 30 01648000 

<100 <100 <100 E 40 01648998 

2–Chloronaphthalene 2–Ethylnaphthalene Naphthalene o,p ́–DDD 1 Station 

(μg/kg) (μg/kg) (μg/kg) (μg/kg) number 

<50 <50 <50 <1 01647997 

<50 <50 E 40 3 01648000 

<100 <100 <100 <1 01648998 

1. 1,1–Dichloro–2–(o-chlorophenyl)–2–(p–chlorophenyl)ethane. 

Appendixes 75 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment 

collected from Rock Creek, Washington, D.C., August 1999—Continued 

Station 

number 

o,p ́–DDE 2 

(μg/kg) 

o,p ́–DDT 3 

(μg/kg) 

Oxychlordane 

(μg/kg) 

p,p ́–DDD 4 

(μg/kg) 

01647997 <1 <2 <1 E 2 

01648000 <1 <2 2 4 

01648998 <1 <2 2 E 6 

Station 

number 

p,p ́–DDE 5 

(μg/kg) 

p,p ́–DDT 6 

(μg/kg) 

Polychlorinated 

biphenyls 

(PCBs) 

(μg/kg) 

p–Cresol 

(μg/kg) 

01647997 2 7 <50 <50 

01648000 4 4 80 80 

01648998 7 8 50 400 

Station Pentachloroanisole 1–Methylphenanthrene Phenanthrene Phenanthridine 

number (μg/kg) (μg/kg) (μg/kg) (μg/kg) 

01647997 <1 <50 240 <50 

01648000 <1 E 30 930 E 10 

01648998 <1 E 30 830 <100 

Station 

number 

C8–Alkylphenol 

(μg/kg) 

2–Chlorophenol 

(μg/kg) 

Phenol 

(μg/kg) 

Bis(2–ethylhexyl)ester 

(μg/kg) 

01647997 <50 <50 <50 420 

01648000 <50 <50 E 30 2,200 

01648998 <100 <100 E 40 2,100 

2. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethylene. 5. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

3. 1,1,1–Trichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethane. 6. 1,1,1–Trichloro–2,2–bis(p–chlorophenyl)ethane. 

4. 1,1–(Dichloro–2,2–bis(p–chlorophenyl)ethane. 

76 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A3. Results of analyses for organic compounds measured in samples of bed sediment

collected from Rock Creek, Washington, D.C., August 1999—Continued

Butylbenzyl phthalate 

(μg/kg) 

Dimethyl phthalate 

(μg/kg) 

Di–n–butyl phthalate 

(μg/kg) 

Diethyl phthalate 

(μg/kg) 

Station 

number 

1,300 <50 E 30 E 10 01647997 

150 <50 90 E 20 01648000 

120 <100 E 50 <100 01648998 

Di–n–octyl phthalate 1–Methylpyrene Pyrene Quinoline Station 

(μg/kg) (μg/kg) (μg/kg) (μg/kg) number 

60 E 20 410 <50 01647997 

<50 50 1,600 <50 01648000 

180 E 40 1,200 <100 01648998 

Terphenyl–d14 

(surrogate, Dibenzothiophene 2,4–Dinitrotoluene 2,6–Dinitrotoluene Station 

percent) (μg/kg) (μg/kg) (μg/kg) number 

83 E 20 <50 <50 01647997 

76 60 <50 <50 01648000 

62 E 50 <100 <100 01648998 

Toxaphene 

(μg/kg) 

trans–Chlordane 

(μg/kg) 

trans–Nonachlor 

(μg/kg) 

trans–Permethrin 

(μg/kg) 

Station 

number 

<200 2 1 <5 01647997 

<200 6 5 <6 01648000 

<200 6 4 17 01648998 

Appendixes 77 
Appendix A4. Results of analyses for trace elements, major elements, and inorganic and 

organic carbon measured in samples of bed sediment collected from 

Rock Creek, Washington, D.C., August 1999

 [All samples are bottom material, whole sediment sieved to less than 2 millimeters, dry weight. Recoveries of surrogate compounds (given by percent) from the analyses are included in the results; μg/g, micrograms per gram; <, less than] 

Station Calcium 

number Station name Date Time (percent as Ca) 

01647997 Portal Branch at North Portal Drive, Washington, D.C. 08/19/1999 1135 0.75 

01648000 Rock Creek at Sherrill Drive, Washington, D.C. 08/18/1999 1405 1.4 

01648998 Rock Creek Q Street, Washington, D.C. 08/17/1999 1120 1.4 

Station Magnesium Potassium Sodium Sulfur 

number (percent as Mg) (percent as K) (percent as Na) (percent as S) 

01647997 0.86 1.7 0.31 0.14 

01648000 1.4 1.4 .34 .17 

01648998 1.5 1.3 .36 .25 

Carbon, Carbon, organic Carbon, 

Station Phosphorus inorganic, plus inorganic, organic, 

number (percent as P) (percent as C) (percent as C) (percent as C) 

01647997 0.12 0.11 2.8 2.7 

01648000 .14 .09 4.4 4.3 

01648998 .17 .13 5.8 5.7 

78 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A4. Results of analyses for trace elements, major elements, inorganic and 

organic carbon measured in samples of bed sediment collected from

Rock Creek, Washington, D.C., August 1999

[All samples are bottom material, whole sediment, field. Recovieries of surrogate compounds (given by percent) from the

 analyses are included in the results; mg/kg, millgram per kilogram]

Aluminum Antimony Arsenic Barium Station 

(percent as Al) (μg/g as Sb) (μg/g as As) (μg/g as Ba) number 

9.0 2.3 5.7 590 01647997 

8.4 2.7 6.9 510 01648000 

8.1 3.3 7.4 500 01648998 

Beryllium Bismuth Cadmium Cerium Station 

(μg/g as Be) (μg/g as Bi) (μg/g as Cd) (μg/g as Ce) number 

4.5 <1 1.3 180 01647997 

4.2 <1 1.2 140 01648000 

3.6 <1 1.5 120 01648998 

Chromium Cobalt Copper Europium Station 

(μg/g as Cr) (μg/g as Co) (μg/g as Cu) (μg/g as Eu) number 

110 25 150 3 01647997 

150 30 130 3 01648000 

160 32 170 2 01648998 

Appendixes 79 
Appendix A4. Results of analyses for trace elements, major elements, and inorganic and 

organic carbon measured in samples of bed sediment collected from 

Rock Creek, Washington, D.C., August 1999—Continued 

Station Gallium Gold Holmium Iron 

number (μg/g as Ga) (μg/g as Au) (μg/g as Ho) (percent as Fe) 

01647997 23 <1 3 5.4 

01648000 21 <1 2 5.6 

01648998 20 <1 2 5.6 

Station Lanthanum Lead Lithium Manganese 

number (μg/g as La) (μg/g as Pb) (μg/g as Li) (μg/g as Mn) 

01647997 97 110 46 790 

01648000 74 98 34 1,700 

01648998 64 150 32 1,900 

Station 

number 

Mercury 

(μg/g as Hg) 

Molybdenum 

(μg/g as Mo) 

Neodymium 

(μg/g as Nd) 

Nickel 

(μg/g as Ni) 

01647997 0.21 12 85 70 

01648000 1.4 9.0 64 94 

01648998 .32 7.7 55 99 

80 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix A4. Results of analyses for trace elements, major elements, inorganic and 

organic carbon measured in samples of bed sediment collected from

Rock Creek, Washington, D.C., August 1999—Continued

Niobium Scandium Selenium Silver Strontium Station 

(μg/g as Nb) (μg/g as Sc) (μg/g as Se) (μg/g as Ag) (μg/g as Sr) number 

13 16 0.8 0.5 100 01647997 

11 23 .9 .6 110 01648000 

10 22 1.0 .5 110 01648998 

Tantalum Thallium Tin Titanium Vanadium Station 

(μg/g as Ta) (μg/g as Tl) (μg/g as Sn) (percent as Ti) (μg/g as V) number 

3 <1 7 0.54 120 01647997 

2 <1 7 .52 140 01648000 

2 <1 8 .43 140 01648998 

Ytterbium Yttrium Zinc Thorium Uranium Station 

(μg/g as Yb) (μg/g as Y) (μg/g as Zn) (μg/g as Th) (μg/g as U) number 

7 72 410 20 5.0 01647997 

5 54 370 14 3.6 01648000 

4 47 450 12 3.3 01648998 

Appendixes 81 
Appendix B1. Laboratory code constituents and parameters for schedule 2001, 

 dissolved pesticides in water, from the U.S. Geological Survey

 National Water-Quality Laboratory (NWQL) in Denver, Colorado, 2001

 —Continued 

Appendix B1. Laboratory code constituents and parameters for schedule 2001, 

dissolved pesticides in water, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; 

μg/L, micrograms per liter; –, no data available] 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

2,6–Diethylaniline 82660 579-66-8 0.0017 μg/L 

Acetochlor 49260 34256-82-1 .0041 μg/L 

Alachlor 46342 15972-60-8 .0024 μg/L 

α–HCH 1 34253 319-84-6 .0046 μg/L 

α–HCH–d6 (surrogate) 2 91065 – .1 percent 

2,6–Diethylaniline 82660 579-66-8 .0017 μg/L 

Atrazine 39632 1912-24-9 .007 μg/L 

Azinphos-methyl 82686 86-50-0 .05 μg/L 

Benfluralin 82673 1861-40-1 .01 μg/L 

Butylate 04028 2008-41-5 .002 μg/L 

Carbaryl 82680 63-25-2 .041 μg/L 

Carbofuran 82674 1563-66-2 .02 μg/L 

Chlorpyrifos 38933 2921-88-2 .005 μg/L 

cis–Permethrin 82687 54774-45-7 .006 μg/L 

Cyanazine 04041 21725-46-2 .018 μg/L 

Dacthal 82682 1861-32-1 .003 μg/L 

Deethylatrazine 04040 6190-65-4 .006 μg/L 

Diazinon 39572 333-41-5 .005 μg/L 

Diazinon–d10 (surrogate) 91063 100155-47-3 .1 percent 

Dieldrin 39381 60-57-1 .0048 μg/L 

Disulfoton 82677 298-04-4 .021 μg/L 

EPTC 3 82668 759-94-4 .002 μg/L 

Ethalfluralin 82663 55283-68-6 .009 μg/L 

Ethoprophos 82672 13194-48-4 .005 μg/L 

Fonofos 04095 944-22-9 .0027 μg/L 

Lindane 39341 58-89-9 .004 μg/L 

Linuron 82666 330-55-2 .035 μg/L 

Malathion 39532 121-75-5 .027 μg/L 

Metolachlor 39415 51218-45-2 .013 μg/L 

Metribuzin 82630 21087-64-9 .006 μg/L 

Molinate 82671 2212-67-1 .0016 μg/L 

Napropamide 82684 15299-99-7 .007 μg/L 

p,p’–DDE 4 34653 72-55-9 .0025 μg/L 

Parathion 39542 56-38-2 .007 μg/L 

Parathion-methyl 82667 298-00-0 .006 μg/L 

Pebulate 82669 1114-71-2 .0016 μg/L 

Pendimethalin 82683 40487-42-1 .01 μg/L 

Phorate 82664 298-02-2 .011 μg/L 

Prometon 04037 1610-18-0 .015 μg/L 

Propachlor 04024 1918-16-7 .01 μg/L 

Propanil 82679 709-98-8 .011 μg/L 

82 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix B1. Laboratory code constituents and parameters for schedule 2001, 

dissolved pesticides in water, from the U.S. Geological Survey

 National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 —Continued 

Parameter 

name 

USGS 

parameter 

code 

CAS 

number 

Reporting 

limit 

Reporting 

unit 

Propargite 

Propyzamide 

Simazine 

82685 

82676 

04035 

2312-35-8 

23950-58-5 

122-34-9 

0.023 

.0041 

.011 

μg/L 

μg/L 

μg/L 

Tebuthiuron 

Terbacil 

Terbufos 

Terbuthylazine 

Thiobencarb 

82670 

82665 

82675 

04022 

82681 

34014-18-1 

5902-51-2 

13071-79-9 

5915-41-3 

28249-77-6 

.016 

.034 

.017 

.1 

.0048 

μg/L 

μg/L 

μg/L 

μg/L 

μg/L 

Triallate 

Trifluralin 

82678 

82661 

2303-17-5 

1582-09-8 

.0023 

.009 

μg/L 

μg/L 

1. α–1,2,3,4,5,6–Hexachlorocyclohexane. 

2. α–1,2,3,4,5,6–Hexachlorocyclohexane–d6. 

3. s–Ethyl dipropylthiocarbamate. 

4. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

Appendixes 83 
Appendix B2. Laboratory code constituents and parameters for schedule 2050, 

dissolved pesticides in water, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; μg/L, micrograms per liter] 

Parameter USGS CAS Reporting Reporting 

name parameter code number limit unit 

2,4,5–T 1 39742 93-76-5 0.04 μg/L 

2,4–D 2 39732 94-75-7 .11 μg/L 

2,4–DB 3 38746 94-82-6 .1 μg/L 

3–Hydroxycarbofuran 49308 16655-82-6 .11 μg/L 

BDMC (surrogate) 4 99835 672-99-1 .1 percent 

Acifluorfen 49315 50594-66-6 .05 μg/L 

Aldicarb 49312 116-06-3 .21 μg/L 

Aldicarb sulfone 49313 1646-88-4 .2 μg/L 

Aldicarb sulfoxide 49314 1646-87-3 .02 μg/L 

Bentazon 38711 25057-89-0 .035 μg/L 

Bromacil 04029 314-40-9 .09 μg/L 

Bromoxynil 49311 1689-84-5 .07 μg/L 

Carbaryl 49310 63-25-2 .024 μg/L 

Carbofuran 49309 1563-66-2 .29 μg/L 

Chloramben, methyl ester 61188 7286-84-2 .14 μg/L 

Chlorothalonil 49306 1897-45-6 .13 μg/L 

Clopyralid 49305 1702-17-6 .42 μg/L 

Dacthal monoacid 49304 887-54-7 .07 μg/L 

Dicamba 38442 1918-00-9 .043 μg/L 

Dichlobenil 49303 1194-65-6 .049 μg/L 

Dichlorprop 49302 120-36-5 .05 μg/L 

Dinoseb 49301 88-85-7 .09 μg/L 

Diuron 49300 330-54-1 .056 μg/L 

DNOC 7 49299 534-52-1 .42 μg/L 

Fenuron 49297 101-42-8 .07 μg/L 

Fluometuron 38811 2164-17-2 .06 μg/L 

Linuron 38478 330-55-2 .021 μg/L 

MCPA 5 38482 94-74-6 .08 μg/L 

MCPB 6 38487 94-81-5 .13 μg/L 

Methiocarb 38501 2032-65-7 .07 μg/L 

Methomyl 49296 16752-77-5 .02 μg/L 

Neburon 49294 555-37-3 .017 μg/L 

Norflurazon 49293 27314-13-2 .042 μg/L 

Oryzalin 49292 19044-88-3 .28 μg/L 

Oxamyl 38866 23135-22-0 .02 μg/L 

Picloram 49291 1918-02-1 .09 μg/L 

Propham 49236 122-42-9 .09 μg/L 

Propoxur 38538 114-26-1 .12 μg/L 

Silvex 39762 93-72-1 .025 μg/L 

Triclopyr 49235 55335-06-3 .07 μg/L 

1. 2,4,5–Trichlorophenoxyacetic acid. 5. 4–(4–Chloro–2–methylphenoxy)acetic acid. 

2. (2,4–Dichlorophenoxy)acetic acid. 6. 4–(4–Chloro–2–methylphenoxy)butanoic acid. 

3. 4–(2,4–Dichlorophenoxy)butyric acid. 7. 4,6–Dinitro–o–cresol. 

4. 4–Bromo–3,5–dimethylphenyl–n–methylcarbamate. 

84 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix B3. Laboratory code constituents and parameters for schedule 2420,

 trace elements in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001— 

Continued 

Appendix B3. Laboratory code constituents and parameters for schedule 2420,

 trace elements in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; 

μg/g, micrograms per gram; –, no data available] 

Parameter 

name 

USGS 

parameter 

code 

CAS 

number 

Reporting 

limit 

Reporting 

unit 

Aluminum 

Antimony 

Arsenic 

Barium 

Beryllium 

34790 

34795 

34800 

34805 

34810 

7429-90-5 

7440-36-0 

7440-38-2 

7440-39-3 

7440-41-7 

0.005 

.1 

.1 

1 

.1 

percent 

μg/g 

μg/g 

μg/g 

μg/g 

Bismuth 

Cadmium 

Calcium 

Cerium 

Chromium 

34816 

34825 

34830 

34835 

34840 

7440-69-9 

7440-43-9 

7440-70-2 

7440-45-1 

7440-47-3 

1 

.1 

.005 

1 

1 

μg/g 

μg/g 

percent 

μg/g 

μg/g 

Cobalt 

Copper 

Europium 

Gallium 

Gold 

34845 

34850 

34855 

34860 

34870 

7440-48-4 

7440-50-8 

7440-53-1 

7440-55-3 

7440-57-5 

1 

1 

1 

1 

1 

μg/g 

μg/g 

μg/g 

μg/g 

μg/g 

Holmium 

Inorganic carbon 

Iron 

Lanthanum 

Lead 

34875 

49269 

34880 

34885 

34890 

7440-60-0 

– 

7439-89-6 

7439-91-0 

7439-92-1 

1 

.01 

.005 

1 

1 

μg/g 

percent 

percent 

μg/g 

μg/g 

Lithium 

Magnesium 

Manganese 

Mercury 

Molybdenum 

34895 

34900 

34905 

34910 

34915 

7439-93-2 

7439-95-4 

7439-96-5 

7439-97-6 

7439-98-7 

1 

.005 

4 

.02 

.5 

μg/g 

percent 

μg/g 

μg/g 

μg/g 

Neodymium 

Nickel 

Niobium 

Organic carbon 

Phosphorus 

34920 

34925 

34930 

49266 

34935 

7440-00-8 

7440-02-0 

7440-03-01 

– 

7723-14-0 

1 

2 

4 

.01 

.005 

μg/g 

μg/g 

μg/g 

percent 

percent 

Potassium 

Scandium 

Selenium 

Silver 

Sodium 

34940 

34945 

34950 

34955 

34960 

7440-09-7 

7440-20-2 

7782-49-2 

7440-22-4 

7440-23-5 

.005 

2 

.1 

.1 

.005 

percent 

μg/g 

μg/g 

μg/g 

percent 

Strontium 

Sulfur 

Tantalum 

Thallium 

Thorium 

34965 

34970 

34975 

04064 

34980 

7440-24-6 

7704-34-9 

7440-25-7 

7440-28-0 

7440-29-1 

2 

.05 

1 

1 

1 

μg/g 

percent 

μg/g 

μg/g 

μg/g 

Appendixes 85 
Appendix B3. Laboratory code constituents and parameters for schedule 2420,

 trace elements in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001— 

Continued 

Parameter 

name 

USGS 

parameter 

code 

CAS 

number 

Reporting 

limit 

Reporting 

unit 

Tin 

Titanium 

Total carbon 

Uranium 

Vanadium 

34985 

49274 

49267 

35000 

35005 

7440-31-5 

7440-32-6 

– 

7440-61-1 

7440-62-2 

1 

.005 

.01 

.1 

2 

μg/g 

percent 

percent 

μg/g 

μg/g 

Ytterbium 

Yttrium 

Zinc 

35015 

35010 

35020 

7440-64-4 

7440-65-5 

7440-66-6 

1 

1 

2 

μg/g 

μg/g 

μg/g 

86 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix B4. Laboratory code constituents and parameters for schedule 2500, 

 organic compounds in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001—Continued 

boratory c d parame

ganic com U.S. Geological Surve

Quality Laboratory ( )

Appendix B4. La ode constituents an ters for schedule 2500, 

or pounds in bed sediment, from the y 

National Water- NWQL , Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; μg/kg, micrograms per kilogram; g, gram;

 g/kg, grams per kilogram; α, alpha; β, beta; –, no data available; N/A, not applicable] 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

1,2,4–Trichlorobenzene 49438 120-82-1 50 μg/kg 

1,2–Dichlorobenzene 49439 95-50-1 50 μg/kg 

1,2–Dimethylnaphthalene 49403 573-98-8 50 μg/kg 

1,3–Dichlorobenzene 49441 541-73-1 50 μg/kg 

1,4–Dichlorobenzene 49442 106-46-7 50 μg/kg 

1,6–Dimethylnaphthalene 49404 575-43-9 50 μg/kg 

1–Methyl–9H–fluorene 49398 1730-37-6 50 μg/kg 

1–Methylphenanthrene 49410 832-69-9 50 μg/kg 

1–Methylpyrene 49388 2381-21-7 50 μg/kg 

2,2’,3,3’,4,4’,5,6,6’–Nonachlorobiphenyl (PCB 207, surrogate) N/A 52663-79-3 .1 percent 

2,2’,3,4,4’,5,6,6’–Octachlorobiphenyl (surrogate) 49276 74472-52-9 .1 percent 

2,2’–Biquinoline 49391 119-91-5 50 μg/kg 

2,3,5,6–Tetramethylphenol 49414 527-35-5 50 μg/kg 

2,3,6–Trimethylnaphthalene 49405 829-26-5 50 μg/kg 

2,4,6–Trichlorophenol 49415 88-06-2 50 μg/kg 

2,4,6–Trimethylphenol 49416 527-60-6 50 μg/kg 

2,4–Dichlorophenol 49417 120-83-2 50 μg/kg 

2,4–Dinitrophenol 49418 51-28-5 50 μg/kg 

2,4–Dinitrotoluene 49395 121-14-2 50 μg/kg 

2,6–Dimethylnaphthalene 49406 581-42-0 50 μg/kg 

2,6–Dinitrotoluene 49396 606-20-2 50 μg/kg 

2–Chloronaphthalene 49407 91-58-7 50 μg/kg 

2–Chlorophenol 49467 95-57-8 50 μg/kg 

2–Ethylnaphthalene 49948 939-27-5 50 μg/kg 

2–Fluorobiphenyl (surrogate) 49279 321-60-8 .1 percent 

2–Methylanthracene 49435 613-12-7 50 μg/kg 

2–Nitrophenol 49420 88-75-5 50 μg/kg 

3,5–Dichlorobiphenyl (surrogate) 49277 34883-41-5 .1 percent 

3,5–Dimethylphenol 49421 108-68-9 50 μg/kg 

4,6–Dinitro–2–methylphenol 49419 534-52-1 50 μg/kg 

4–Bromophenylphenylether 49454 101-55-3 50 μg/kg 

4–Chloro–3–methylphenol 49422 59-50-7 50 μg/kg 

4–Chlorophenyl phenyl ether 49455 7005-72-3 50 μg/kg 

4–Nitrophenol 49423 100-02-7 50 μg/kg 

4,5–Methylenephenanthrene 49411 203-64-5 50 μg/kg 

Acenaphthene 49429 83-32-9 50 μg/kg 

Acenaphthylene 49428 208-96-8 50 μg/kg 

Acridine 49430 260-94-6 50 μg/kg 

Aldrin 49319 309-00-2 1 μg/kg 

α–Endosulfan 49332 959-98-8 1 μg/kg 

Appendixes 87 
Appendix B4. Laboratory code constituents and parameters for schedule 2500, 

 organic compounds in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001—Continued 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

α–HCH 1 49338 319-84-6 1 μg/kg 

α–HCH–d6 (surrogate) 2 49275 – .1 percent 

Anthracene 49434 120-12-7 50 μg/kg 

Anthraquinone 49437 84-65-1 50 μg/kg 

Azobenzene 49443 103-33-3 50 μg/kg 

Benz[a]anthracene 49436 56-55-3 50 μg/kg 

Benzo[a]pyrene 49389 50-32-8 50 μg/kg 

Benzo[b]fluoranthene 49458 205-99-2 50 μg/kg 

Benzo[c]cinnoline 49468 230-17-1 50 μg/kg 

Benzo[ghi]perylene 49408 191-24-2 50 μg/kg 

Benzo[k]fluoranthene 49397 207-08-9 50 μg/kg 

β–HCH 3 49339 319-85-7 1 μg/kg 

Bis(2–chloroethoxy)methane 49401 111-91-1 50 μg/kg 

Bis(2–chloroethyl)ether 49456 111-44-4 50 μg/kg 

Bis(2–chloroisopropyl)ether 49457 108-60-1 50 μg/kg 

Bis(2–ethylhexyl)phthalate 49426 117-81-7 50 μg/kg 

Butylbenzyl phthalate 49427 85-68-7 50 μg/kg 

C8–Alkylphenol 49424 – 50 μg/kg 

Carbazole 49449 86-74-8 50 μg/kg 

Chloroneb 49322 2675-77-6 5 μg/kg 

Chrysene 49450 218-01-9 50 μg/kg 

cis–Chlordane 49320 5103-71-9 1 μg/kg 

cis–Nonachlor 49316 5103-73-1 1 μg/kg 

cis–Permethrin 49349 54774-45-7 5 μg/kg 

Dacthal 49324 1861-32-1 5 μg/kg 

Di–n–butyl phthalate 49381 84-74-2 50 μg/kg 

Di–n–octyl phthalate 49382 117-84-0 50 μg/kg 

Dibenz[ah]anthracene 49461 53-70-3 50 μg/kg 

Dibenzothiophene 49452 132-65-0 50 μg/kg 

Dieldrin 49331 60-57-1 1 μg/kg 

Diethyl phthalate 49383 84-66-2 50 μg/kg 

Dimethyl phthalate 49384 131-11-3 50 μg/kg 

Endrin 49335 72-20-8 2 μg/kg 

Fluoranthene 49466 206-44-0 50 μg/kg 

Fluorene 49399 86-73-7 50 μg/kg 

Heptachlor 49341 76-44-8 1 μg/kg 

Heptachlor epoxide 49342 1024-57-3 1 μg/kg 

Hexachlorobenzene 49343 118-74-1 1 μg/kg 

Hexachlorobutadiene 49448 87-68-3 50 μg/kg 

1. α–1,2,3,4,5,6–Hexachlorocyclohexane. 

2. α–1,2,3,4,5,6–Hexachlorocyclohexane–d6 

3. β–1,2,3,4,5,6–Hexachlorocyclohexane. 

88 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix B4. Laboratory code constituents and parameters for schedule 2500, 

 organic compounds in bed sediment, from the U.S. Geological Survey 

National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001—Continued 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

Hexachlorocyclopentadiene 49489 77-47-4 50 μg/kg 

Hexachloroethane 49453 67-72-1 50 μg/kg 

Indeno[1,2,3–cd]pyrene 49390 193-39-5 50 μg/kg 

Isodrin 49344 465-73-6 1 μg/kg 

Isophorone 49400 78-59-1 50 μg/kg 

Isoquinoline 49394 119-65-3 50 μg/kg 

Lindane 49345 58-89-9 1 μg/kg 

Mirex 49348 2385-85-5 1 μg/kg 

N–Nitrosodi–n–propylamine 49431 621-64-7 50 μg/kg 

N–Nitrosodiphenylamine 49433 86-30-6 50 μg/kg 

Naphthalene 49402 91-20-3 50 μg/kg 

Nitrobenzene 49444 98-95-3 50 μg/kg 

Nitrobenzene–d5 (surrogate) 49280 4165-60-0 .1 percent 

o,p’–DDD 4 49325 53-19-0 1 μg/kg 

o,p’–DDE 5 49327 3424-82-6 1 μg/kg 

o,p’–DDT 6 49329 789-02-6 2 μg/kg 

o,p’–Methoxychlor 49347 30667-99-3 5 μg/kg 

Oxychlordane 49318 27304-13-8 1 μg/kg 

p,p’–DDD 7 49326 72-54-8 1 μg/kg 

p,p’–DDE 8 49328 72-55-9 1 μg/kg 

p,p’–DDT 9 49330 50-29-3 2 μg/kg 

p,p’–Methoxychlor 49346 72-43-5 5 μg/kg 

p–Cresol 49451 106-44-5 50 μg/kg 

Pentachloroanisole 49460 1825-21-4 1 μg/kg 

Pentachloronitrobenzene 49446 82-68-8 50 μg/kg 

Pentachlorophenol 49425 87-86-5 50 μg/kg 

Phenanthrene 49409 85-01-8 50 μg/kg 

Phenanthridine 49393 229-87-8 50 μg/kg 

Phenol 49413 108-95-2 50 μg/kg 

Polychlorinated biphenyls 49459 1336-36-3 50 μg/kg 

Pyrene 49387 129-00-0 50 μg/kg 

Quinoline 49392 91-22-5 50 μg/kg 

Terphenyl–d14 (surrogate) 49278 1718-51-0 .1 percent 

Total carbon 49272 – .1 g/kg 

Toxaphene 49351 8001-35-2 200 μg/kg 

trans–Chlordane 49321 5103-74-2 1 μg/kg 

trans–Nonachlor 49317 39765-80-5 1 μg/kg 

trans–Permethrin 49350 51877-74-8 5 μg/kg 

4. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethane. 7. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethane. 

5. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethylene. 8. 1,1–Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

6. 1,1,1–Trichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethane. 9. 1,1,1–Trichloro–2,2–bis(p–chlorophenyl)ethane. 

Appendixes 89 
Appendix B5. Laboratory code constituents and parameters for schedule 2701,

 major ions in water, from the U.S. Geological Survey 

 National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; 

mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microsiemens per centimeter; 

 –, no data available] 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

Calcium (dissolved) 00915 7440-70-2 0.011 mg/L 

Chloride (dissolved) 00940 16887-00-6 .08 mg/L 

Fluoride (dissolved) 00950 16984-48-8 .16 mg/L 

Iron (dissolved) 01046 7439-89-6 10 μg/L 

Magnesium (dissolved) 00925 7439-95-4 .008 mg/L 

Manganese (dissolved) 01056 7439-96-5 3.2 μg/L 

pH, laboratory 00403 – .1 standard units 

Potassium (dissolved) 00935 7440-09-7 .09 mg/L 

Residue, 180 degrees Celsius 70300 – 10 mg/L 

Silica (dissolved) 00955 7631-86-9 .09 mg/L 

Sodium (dissolved) 00930 7440-23-5 .06 mg/L 

Specific conductance, laboratory 90095 – 2.6 μS/cm 

Sulfate (dissolved) 00945 14808-79-8 .11 mg/L 

Appendix B6. Laboratory code constituents and parameters for schedule 2702,

 nutrients in water, from the U.S. Geological Survey

 National Water-Quality Laboratory (NWQL), Denver, Colorado, 2001

 [USGS, U.S. Geological Survey; CAS, Chemical Abstracts Service registry numbers; 

mg/L, milligrams per liter; –, no data available] 

USGS 

Parameter parameter CAS Reporting Reporting 

name code number limit unit 

Nitrogen, ammonia (dissolved as N) 00608 7664-41-7 0.041 mg/L 

Nitrogen, ammonia plus organic nitrogen (dissolved as N) 00623 17778-88-0 .1 mg/L 

Nitrogen, ammonia plus organic nitrogen (total as N) 00625 17778-88-0 .08 mg/L 

Nitrogen, nitrite (dissolved as N) 00613 14797-65-0 .006 mg/L 

Nitrogen, nitrite plus nitrate (dissolved as N) 00631 – .047 mg/L 

Phosphorus (dissolved as P) 00666 7723-14-0 .006 mg/L 

Phosphorus (total as P) 00665 7723-14-0 .0037 mg/L 

Phosphorus, phosphate, ortho (dissolved as P) 00671 14265-44-2 .018 mg/L 

90 Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999–2000 
Appendix C. Selected transformation products from pesticides discussed in this report 

[Part of the suite of pesticides and organic compounds that was measured in Rock Creek during 1999–2000] 

Transformation product	 Parent compound 

Aldicarb sulfone Aldicarb 

Aldicarb sulfoxide Aldicarb 

Dacthal, monoacid Dacthal 

Dieldrin Aldrin (Dieldrin was also applied as a pesticide) 

2,6–Diethylanaline Alachlor 

α–HCH 1 Lindane 2 

3–Hydroxycarbofuran Carbofuran 

o,p’–DDD 3 and p,p’–DDD 4 DDT 5 

o,p’–DDE 6 and p,p’–DDE 7 DDT 5 

Desethylatrazine Atrazine 

Heptachlor epoxide Heptachlor 

1. α–1,2,3,4,5,6–Hexachlorocyclohexane. 

2.	 Lindane is a technical mixture consisting primarily of γ–HCH (gamma–1,2,3,4,5,6–hexachlorocyclohexane),

 but may also contain α–HCH . 

3. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethane. 

4. 1,1–(Dichloro–2,2–bis(p–chlorophenyl)ethane. 

5. 1,1,1–Trichloro–2,2–bis(p–chlorophenyl)ethane. 

6. 1,1–Dichloro–2–(o–chlorophenyl)–2–(p–chlorophenyl)ethylene. 

7. 1,1–(Dichloro–2,2–bis(p–chlorophenyl)ethylene. 

Appendixes 91