U.S. Department of the Interior

U.S. Geological Survey

Data Series 738

Prepared in cooperation with the San Antonio Water System

Surface-Water Quality in the Upper San Antonio River Basin, 

Bexar County, Texas, 1992–98

§¦ ̈

§ ̈¦37

§ ̈¦

LOOP 410

£¤ San Antonio

£¤

£¤

£¤ £¤

Helotes

Martinez Creek

Leon Creek

Salado Creek

1604

90 87 35

10

16

281

WILSON

 COUNTY

BEXAR COUNTY

ATASCOSA COUNTY

COMAL COUNTY 

BANDERA COUNTY

GUADALUPE

COUNTY

KENDALL COUNTY 

MEDINA COUNTY

COUNTY

KERR 

LOOP 13

Rosillo Creek

Calaveras

Lake

Braunig 

Lake

Mitchell

Lake

Medina

Lake

Elm Creek

San Antonio River

Chupaderas Creek

Calaveras Creek

Medio Creek

San Antonio River

Medina River

Cibolo Creek

North Prong Medina River

Apach e Creek

#

#

#

#

# !

!

!

!

Dos Rios

Leon Creek

Medio Creek 

Salado Creek

08181500

08178565

08178800

08181800

08181480
Cover: Medina River upstream from U.S. Geological Survey streamflow-gaging station 08181500 Medina 

River at San Antonio, Texas, April 30, 2010. 
Surface-Water Quality in the Upper San 

Antonio River Basin, Bexar County, Texas, 

1992–98

By J. Ryan Banta, Richard N. Slattery, and Cassi L. Crow

Prepared in cooperation with the San Antonio Water System

Data Series 738

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

This and other USGS information products are available at http://store.usgs.gov/

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1-888-ASK-USGS

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U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Banta, J.R., Slattery, R.N., and Crow, C.L., 2012, Surface-water quality in the upper San Antonio River Basin, Bexar 

County, Texas, 1992–98: U.S. Geological Survey Data Series 738, 60 p., 3 apps.
iii

Contents

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

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

Purpose and Scope .............................................................................................................................1

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

Data-Collection Methods .............................................................................................................................3

Water-Quality Sample Collection ......................................................................................................5

Periodic Sample Collection .......................................................................................................5

Stormflow Sample Collection ...................................................................................................5

Laboratory Analysis .............................................................................................................................5

Streamflow Data Collection ...............................................................................................................5

Quality Assurance ................................................................................................................................7

Water-Quality Data .......................................................................................................................................7

Physical Properties ..............................................................................................................................7

Major Ions .............................................................................................................................................8

Nutrients ................................................................................................................................................8

Trace Elements .....................................................................................................................................8

Organic Compounds ..........................................................................................................................11

References ...................................................................................................................................................11

Appendixes (available at http://pubs.usgs.gov/ds/738/)

1. Water-quality data of routine samples collected during 1992–98 in the study 

area, Bexar County, Texas 

2. Water-quality data of stormflow samples collected during 1992–98 in the 

study area, Bexar County, Texas 

3. Water-quality data of quality-assurance samples collected during 1992–98 in 

the study area, Bexar County, Texas 

Figures

1. Map showing location of data-collection sites in the study area, Bexar 

County, Texas ................................................................................................................................2

2. Land-cover map and data-collection sites in the study area, Bexar County, 

Texas, 1992 ....................................................................................................................................4

3. Graphs showing daily mean streamflow at five U.S. Geological Survey 

streamflow-gaging stations during 1992–98 ...........................................................................6

4. Graphs showing water-quality data of selected nutrients in filtered periodic 

and stormflow samples in the study area, Bexar County, Texas, 1992–98 .........................9

5. Graphs showing water-quality data of selected trace elements in unfiltered 

periodic and stormflow samples in the study area, Bexar County, Texas, 1992–98 .......10

Tables

1. Data-collection sites in the study area, Bexar County, Texas ............................................13

2. Land-cover type and percentage of occurrence in the study area, Bexar County, 

Texas, 1992 ..................................................................................................................................14
iv

3. Dates of periodic and stormflow sampling events in the study area, Bexar 

County, Texas, 1992–98 .............................................................................................................15

4. Summary statistics of detected concentrations of periodic and stormflow 

samples collected from the study area, Bexar County, Texas, 1992–98 ...........................16

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 Square kilometer (km2)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

SI to Inch/Pound

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Volume

liter (L) 0.2642 gallon (gal)

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

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

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

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

25 °C). 

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

or micrograms per liter (μg/L). 
Surface-Water Quality in the Upper San Antonio River 

Basin, Bexar County, Texas, 1992–98

By J. Ryan Banta, Richard N. Slattery, and Cassi L. Crow

Abstract 

The potential effects of chemicals in rivers and 

streams on human health or the ecology have long been a 

source of concern to water managers. Chemicals in rivers 

may result from natural or anthropogenic sources (such 

as industrial or residential practices) which are commonly 

associated with urbanized watersheds. The U.S. Geological 

Survey, in cooperation with the San Antonio Water System, 

examined water-quality data collected from periodic and 

stormflow sampling events at five sites in the upper San 

Antonio River Basin during 1992–98. These water-quality 

data were compared among sites as well as between 

periodic and stormflow events. The samples were collected 

from five continuous streamflow-gaging stations in Bexar 

County, Texas. Samples were analyzed for major ions, 

nutrients, trace elements, and organic compounds, including 

selected pesticides. 

The reported concentrations for the measured constituents 

varied among sites as well as between periodic and stormflow 

samples. Patterns for some constituents, such as nutrients, 

were observed; however, consistent patterns were not always 

observed for all analytes. For example, median concentrations 

for filtered ammonia, nitrate plus nitrite, organic nitrogen, 

and phosphorus generally were greater in periodic samples 

collected from the Medina and SAR Elmendorf sites as 

compared to samples collected from the other sites. Median 

concentrations of trace elements measured in periodic 

samples were generally less than concentrations measured in 

stormflow samples. In general, most of the concentrations of 

analyzed organic compounds were less than the laboratory 

reporting levels. 

Introduction

The potential effects of chemical contributions to rivers 

and streams on human health or the ecology are a source of 

concern for water managers (U.S. Environmental Protection 

Agency, 2012a). Chemicals in rivers may result from natural 

or anthropogenic sources (such as industrial or residential 

practices) which are commonly associated with urbanized 

watersheds (U.S. Environmental Protection Agency, 2012a). 

For example, arsenic is a naturally occurring element in the 

environment; however, arsenic also can enter the environment 

as a result of glass and electronic production wastes (U.S. 

Environmental Protection Agency, 2012b). Some chemicals 

do not naturally occur in the environment, such as 

organochlorine pesticides which can enter the environment 

as a result of agricultural practices (U.S. Environmental 

Protection Agency, 2012b).

In 1990, San Antonio, Texas, covered approximately 

333 square miles (mi2) (U.S. Census Bureau, 1996); by 2000, 

San Antonio had increased to approximately 406 mi2 (U.S. 

Census Bureau, 2001a). Similarly, the population increased 

from about 0.93 million people in 1990 to more than 1.1 

million people in 2000, a 22 percent increase (U.S. Census 

Bureau, 2001b). Human activities in developed areas can 

potentially affect downstream river systems, especially during 

storm events when surface-water runoff from developed 

areas might carry chemicals with it, thereby potentially 

degrading the receiving water bodies. For example, elevated 

concentrations of some nutrients, possibly from wastewater 

treatment plants or application of fertilizers, have been 

observed in the San Antonio River (San Antonio River 

Authority, 2012). Elevated nutrient concentrations might 

result in eutrophication of the river (Dubrovsky and others, 

2010). To gain a better understanding of the concentrations 

of selected chemicals in the San Antonio River, the U.S. 

Geological Survey (USGS), in cooperation with the San 

Antonio Water System, examined water-quality data collected 

from periodic and stormflow sampling events during 1992–98. 

Purpose and Scope

The purpose of this report is to describe the chemical 

and hydrologic data collected from periodic and stormflow 

samples during 1992–98 from five continuous streamflowgaging stations in the upper San Antonio River Basin, Bexar 

County, Tex. (fig. 1). Samples were analyzed for major ions, 

nutrients, trace elements, and organic compounds, including 

selected pesticides. These water-quality data were compared 

among sites, as well as between periodic and stormflow 
Figure 1. Location of data-collection sites in the study area, Bexar County, Texas.

§¦ ̈

§ ̈¦37

LOOP 410

£¤ San Antonio

£¤

£¤

£¤

Helotes

Martin

Leon Creek

Salado Creek

1604

90 

35

16

281

98°

98°40'

99°00'

99°20'

29°40'

29°20'

WILSON

 COUNTY

ATASCOSA COUNTY

COMAL COUNTY 

BANDERA COUNTY

KENDALL COUNTY 

MEDINA COUNTY

COUNTY KERR 

LOOP 13

Rosillo Creek

Braunig 

Lake

Mitchell

Lake

MedinaLake

Elm

Creek

San A

C

Calaveras Creek

Medio Creek

San Antonio River

Medina River

Cibolo Creek

North Prong Medina River

Apach e Creek

#

#

#

#

#

!

!

!

!

Dos Rios

Leon Creek

Medio Creek 

Salado Creek

08181500

08178565

08178800

08181800

08181480

0 10 20 MILES

0 10 20 KILOMETERS

Medio Creek

!

08181480

#

Cumulative drainage area for most downstream U.S. Geological Survey (USGS) streamflow-gaging station (table 1) Leon 35 (USGS station 08181480) SAR 410 (USGS station 08178565) Salado 13 (USGS station 08178800) Medina (USGS station 08181500) SAR Elmendorf (USGS station 08181800)Study area boundaryCity boundaryUSGS streamflow-gaging station with

 USGS station number—See table 1San Antonio Water System wastewater  treatment plant with site identifier

EXPLANATION 

Base modified from U.S. Geological Survey digital data, 1:100,000Albers equal-area projectionNorth American Datum of 1983
Introduction 3

events. Results also were compared with Texas Commission 

on Environmental Quality (TCEQ) surface water standards 

(Texas Commission on Environmental Quality, 2010). In this 

report, comparisons to TCEQ surface water standards were for 

general contextual purposes only because none of the samples 

were collected for regulatory compliance purposes.

Description of Study Area

The upper San Antonio River Basin is approximately 

1,741 mi2 and is defined in this report as the cumulative 

watershed area upstream from five existing USGS streamflowgaging stations in Bexar County, Tex. (fig. 1, table 1 at end 

of report). The five USGS streamflow-gaging stations are as 

follows: 08181480 Leon Creek at Interstate Highway 35, 

San Antonio, Tex. (hereinafter referred to as the “Leon 35 

site”); 08178565 San Antonio River at Loop 410, San Antonio, 

Tex. (hereinafter referred to as the “SAR 410 site”); 08178800 

Salado Creek at Loop 13, San Antonio, Tex. (hereinafter 

referred to as the “Salado 13 site”); 08181500 Medina River 

at San Antonio, Tex. (hereinafter referred to as the “Medina 

site”); and 08181800 San Antonio River near Elmendorf, 

Tex. (hereinafter referred to as the “SAR Elmendorf site”). 

The SAR Elmendorf site is downstream from the confluence 

of the watersheds represented at the other four sites and is 

considered an integrator site for all the watersheds in the 

study area.

The sources of streamflow in the San Antonio River, 

as measured at the SAR Elmendorf site, are from springs 

discharging within the San Antonio city limits, tributaries, 

and stormflow from rainfall runoff. As the San Antonio River 

and its tributaries flow through different land-cover types, 

the types of land cover and associated human activities might 

influence the downstream water quality. For example, as a 

river passes through urbanized areas, the water quality might 

be affected by byproducts of industrial activities. Land cover 

in the drainage watersheds was categorized as “developed,” 

“undeveloped,” and “cultivated” (modified from the 1992 

National Land Cover Dataset [NLCD]) (Vogelmann and 

others, 2001) (fig. 2, table 2 at end of report). Developed 

land cover includes low intensity residential, high intensity 

residential, and commercial/industrial/transportation. 

Undeveloped land cover includes open water, bare rock/sand/

clay, quarries/strip mines/gravel pits, transitional, deciduous 

forest, evergreen forest, mixed forest, shrubland, grasslands/

herbaceous, and emergent herbaceous wetlands. Cultivated 

land cover includes pasture/hay, row crops, small grains, and 

urban/recreational grasses. 

The watershed with the highest percentage of developed 

land cover was the SAR 410 site (78.8 percent) (table 2). 

Because of the high percentage of developed land, the effects 

of urbanization on water-quality might be observed more 

readily at this site as compared to the other sites. Conversely, 

the watershed with the largest percentage of undeveloped land 

cover was the Medina site (76.3 percent), which also had the 

largest percentage of cultivated areas (17.8 percent), excluding 

the SAR Elmendorf site (18.3 percent). The potential effects 

of agricultural activities might be more readily observed at the 

Medina site than the other sites.

In addition to potential effects on water quality related 

to differences in land cover, there were four large wastewater 

treatment plants operating in the study area during 1992–98 

(fig. 1). The Medio Creek and Leon Creek wastewater 

treatment plants discharge into tributaries of the Medina River, 

upstream from the Medina site. The Salado Creek and Dos 

Rios wastewater treatment facilities discharge into Salado 

Creek and San Antonio River, upstream of the SAR Elmendorf 

site. The combined average annual discharge from those four 

wastewater treatment facilities was approximately 47,200 

million gallons per year (200 cubic feet per second) during 

1992–98 (Gregg Eckhardt, San Antonio Water System, written 

commun., 2012). 

Data-Collection Methods

Periodic and stormflow water-quality samples 

(hereinafter referred to as “periodic samples” and “stormflow 

samples,” respectively) were collected from five sites during 

1992–98 (fig. 1, table 1). Periodic and stormflow samples 

collected at each of the sites were analyzed for physical 

properties, major ions, nutrients, trace elements, and organic 

compounds, including selected pesticides. 
Figure 2. Land-cover map and data-collection sites in the study area, Bexar County, Texas, 1992. 

San Antonio

Base modified from U.S. Geological Survey 1:100,000-scale digital dataAlbers equal-area projectionNorth American Datum of 1983

U.S. Geological Survey N

WILSON COUNTY

ATASCOSA COUNTY

COMAL COUNTY BANDERA COUNTY

KENDALL COUNTY 

MEDIN

A COUNTY

COUNTY KERR 

29°40'

29°20'

98°40'

99°00'

99°20'

08181500

08178565

08178800

08181800

08181480#

#

#

#

#

EXPLANATION

 Shrubland Grasslands/herbaceous Pasture/hay Row crops Small grains Urban/recreational grasses Emergent herbaceous wetlandsStudy area boundaryU.S. Geological Survey (USGS)  streamflow-gaging station with USGS station number —See table 1

Land cover Open water Low intensity residential High intensity residential Commercial/industrial/ transportation Bare rock/sand/clay Quarries/strip mines/gravel pits Transitional barren Deciduous forest Evergreen forest Mixed forest

 08178628

#

0 10 20 MILES

0 10 20 KILOMETERS

9

Braunig 

Lak

Mitchell

Lake

MedinaLake

Elm Creek

San 

Calaveras Creek

Medio Creek

San Antonio River

Medina River

Cibolo Creek

North Prong Medina River

Apach e Creek

Mar

Leon Creek

Salado

Creek

Rosillo

Creek
Data-Collection Methods 5

Water-Quality Sample Collection 

Periodic Sample Collection

Periodic samples were collected approximately every 

2–3 months (fig. 3, table 3 at end of report). Periodic samples 

were not intended to represent base-flow conditions; the 

periodic samples were collected during a range of streamflow 

conditions at the sites from 1992–95. Sample preparation, 

collection, and processing techniques followed standard 

USGS protocols (Wells and others, 1990; U.S. Geological 

Survey, variously dated). Periodic samples analyzed for 

physical properties, major ions, nutrients, and trace elements 

were collected by using a depth-integrated method (Wells 

and others, 1990; U.S. Geological Survey, variously dated). 

Subsamples were collected at 10 to 20 equally spaced intervals 

across the stream by raising and lowering a narrow-mouth, 

1-liter glass bottle through the water column at a constant 

rate. The subsamples were then composited into one to two 

larger intermediate glass containers for transporting. Periodic 

samples analyzed for organic compounds were collected into 

individual bottles from the stream at the centroid of flow (U.S. 

Geological Survey, variously dated). All samples were then 

chilled and transported to the USGS South Texas Program 

Office in San Antonio, Tex., for processing. 

To process a composited periodic sample, the 

intermediate glass containers were transferred to an 8-liter 

polyethylene churn (U.S. Geological Survey, variously dated). 

A churning rate of about 9 inches per second was established 

on the composited sample and maintained while whole (raw) 

water samples were withdrawn from the churn splitter first. 

Subsamples were drawn from the churn by using a peristaltic 

pump and filtered through a 0.45 micron filter for the analysis 

of filtered constituents (U.S. Geological Survey, variously 

dated). Samples for organic compounds were kept in their 

original collection bottles. All samples were then chilled and 

sent to the USGS National Water Quality Laboratory (NWQL) 

in Denver, Colorado, for laboratory analysis. 

Stormflow Sample Collection

Stormflow samples were collected from 1993–98 during 

periods when streamflow at the sites was affected by runoff 

associated with heavy rainfall. Stormflow samples were 

collected for physical properties, major ions, nutrients, trace 

elements, and organic compounds by using a point-integrating 

sampling method (U.S. Geological Survey, variously dated). 

The sample was drawn through a fixed intake mounted in 

the stream channel using a suction-lift type automatic sampler. 

The automatic sampler was programmed to begin sampling 

when streamflow exceeded a predetermined threshold and 

then fill as many as four 4-liter bottles at fixed-time intervals 

during the stormflow event. The samples were retrieved at 

the end of each stormflow event or after all four bottles were 

filled. The samples were then chilled and transported to the 

USGS South Texas Program Office for processing. 

To process the stormflow samples, the four bottles were 

composited into a Teflon-lined stainless-steel churn, which 

represented the event mean concentration. As with the periodic 

samples, a churning rate of about 9 inches per second was 

established on the composited sample and maintained while 

whole (raw) water samples were withdrawn from the churn 

splitter first. Subsamples analyzed for filtered constituents 

were then drawn from the churn and filtered through a 0.45 

micron filter (U.S. Geological Survey, variously dated). 

Unfiltered and filtered samples were then chilled and sent to 

the NWQL for laboratory analysis.

Laboratory Analysis

Composited water-quality samples were analyzed 

for the following physical properties: dissolved oxygen, pH, 

specific conductance, biochemical oxygen demand (BOD), 

dissolved solids, suspended solids, and alkalinity. Sample 

processing was done at the USGS South Texas Program 

Office by using methods described in the USGS National 

Field Manual for the Collection of Water Quality Data (U.S. 

Geological Survey, variously dated). BOD samples were 

collected, processed, and analyzed by using methods described 

by Delzer and McKenzie (1999). Major ions, nutrients, and 

organic compounds were analyzed and reported by the NWQL 

(appendix 1). Major ion concentrations were measured by 

using methods described by Fishman and Friedman (1989) 

and Fishman (1993). Nutrient concentrations were measured 

by using methods described by Patton and Truitt (1992) and 

Fishman (1993). Trace element concentrations were measured 

by using methods described by Garbarino and Struzeski 

(1998). Organic compounds were measured by using methods 

described by Wershaw and others (1983), Fishman (1993), 

U.S. Environmental Protection Agency (1984, 1999), and 

Clesceri and others (1998). 

Quantified values reported by the NWQL represent 

measured concentrations greater than or equal to the 

laboratory reporting level, as determined by the laboratory at 

the time of analysis. Censored values reported by the NWQL 

represent measured concentrations less than the laboratory 

reporting level (“<LRL,” where LRL is the reporting level), 

as determined by the laboratory at the time of analysis. In 

some cases, the measured concentration was greater than the 

detection level but less than the reporting level. In these cases, 

the value is reported with an “E” (estimated) remark code 

(Childress and others, 1999). 

Streamflow Data Collection

Streamflow was measured at each of the five USGS 

streamflow-gaging stations by following methods described 

by Buchanan and Somers (1969) (since superseded by 

Turnipseed and Sauer [2010]) and Rantz and others (1982a, b). 

Streamflow was measured at 15-minute intervals and 

transmitted every 4 hours by a Geostationary Operational 

Environmental Satellite (GOES) to the USGS National Water 
6 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Figure 3. Daily mean streamflow at five U.S. Geological Survey streamflow-gaging stations during 1992–98 (table 1). A, Leon 35 site 

(station 08181480 Leon Creek at Interstate Highway 35, San Antonio, Tex.). B, SAR 410 site (station 08178565, San Antonio River at Loop 

410, San Antonio, Tex.). C, Salado 13 site (station 08178800, Salado Creek at Loop 13, San Antonio, Tex.). D, Medina site (station 08181500, 

Medina River at San Antonio, Tex.). E, SAR Elmendorf site (station 08181800, San Antonio River near Elmendorf, Tex.). 

A. Leon 35 site

B. SAR 410 site

C. Salado 13 site

D. Medina site

E. SAR Elmendorf site

1992 1993 1994 1995 1996 1997 1998 1999

Year

0.1

1

10

100

1,000

10,000

100,000

0.1

1

10

100

1,000

10,000

100,000

0.1

1

10

100

1,000

10,000

100,000

0.1

1

10

100

1,000

10,000

100,000

0.1

1

10

100

1,000

10,000

100,000

Daily mean streamflow, in cubic feet per second

EXPLANATION

Periodic samples collected

Stormflow samples collected

Daily mean streamflow less than

 0.1 cubic foot per second
Water-Quality Data 7

Information System (NWIS) database (U.S. Geological 

Survey, 2012). Streamflow measurements were recorded at the 

streamflow-gaging stations at the time periodic samples were 

collected. Event mean streamflow, which was the average flow 

between the start time and end time of the sample collection, 

was reported for stormflow samples. 

Quality Assurance

USGS quality-assurance procedures were followed for 

collecting and processing water-quality samples to evaluate 

the extent of contamination introduced during sampling, 

sample processing, shipping, and laboratory analysis (U.S. 

Geological Survey, variously dated). For example, the 

autosamplers and collection bottles were cleaned between 

sample collections by using a soap solution, hydrochloric acid, 

and deionized water rinses according to USGS protocols (U.S. 

Geological Survey, variously dated). Three field blank quality 

assurance samples were collected for analysis of selected 

organic compounds (organochlorine pesticides and aroclors) 

at three of the five sites (Leon 35, SAR 410, and Medina sites) 

on September 21, 1993. Field blank samples were processed 

by pumping pesticide-grade blank water, certified to contain 

undetectable concentrations of constituents to be analyzed, 

through the auto-sampler tubing and into collection bottles. 

No quantified values were reported for selected organic 

compounds in any of the field blank samples, indicating 

that contamination is likely negligible for those measured 

constituents (appendix 3). 

Water-Quality Data

The collected water-quality samples were grouped into 

two categories: periodic samples and stormflow samples. The 

periodic samples were collected during 1992–95, whereas 

the stormflow samples were collected during 1993–98. The 

subsequent discussion of the measured concentrations at the 

sites and by sample type (periodic and stormflow) was written 

with the assumption that there were not substantial changes 

in watershed characteristics that might have affected sample 

concentrations during 1992–98. For example, the effects of 

potential development increases within the watersheds were 

assumed to be constant during the study period. It was also 

assumed that there were not any notable changes within the 

watershed between 1995 and 1998, which would be reflected 

in the stormflow samples but not the periodic samples, 

because the periodic samples were not collected during 1995–

98. In addition, grouping samples into periodic and stormflow 

categories assumes that antecedent conditions, such as the 

length of time between stormflow events and the intensity of 

rainfall during stormflow events, had minimal effects on the 

measured concentrations. 

Periodic samples were collected from all five sites during 

the same sampling event. Collecting the samples from all five 

sites during the sampling event reduced the potential biasing 

effects of temporal differences when making comparisons 

among watersheds. For example, if the Leon 35 site was 

sampled 5 times and the SAR 410 site was sampled 10 times, 

then potential differences in water-quality data among the sites 

might be related to physical differences among the watersheds, 

such as land-cover types, or might be because the samples 

were collected during different times. Ten periodic samples 

were typically analyzed for the full suite of analytes (field 

properties, major ions, nutrients, and organic compounds); 

however, in a few instances, sampling or analytical issues 

prevented measurements. Nine additional periodic waterquality samples were collected at all five sites during the study 

period for a subset of analytes. These data were included in 

the dataset when the analyzed suite matched the analyzed suite 

of periodic samples (for example, major ions and nutrients); 

therefore, appendix 1 includes all samples, which vary in 

number by analyte. 

Stormflow samples were collected at up to five sites 

during the same rainfall event. Because of instrumentation 

issues, however, only two rainfall events were sampled at 

all five sites (table 3). As a result of sampling different 

rainfall events at different sites, stormflow sample data from 

each site might be temporally biased. Several rainfall events 

were sampled at three or more of the sites, and thus the 

datasets grouped by watershed were assumed to represent 

similar conditions, so that comparisons among sites could 

be made. It is possible, however, that differences also were 

a result of different hydrologic conditions during the time 

of sampling. The stormflow sample data are presented in 

appendix 2.

To help water managers assess the general health of water 

bodies, the TCEQ established surface water quality standards 

for human health protection (water and fish), hereinafter 

referred to as “TCEQ standards” (Texas Commission on 

Environmental Quality, 2010). Comparisons of median 

concentrations to TCEQ standards in this report are for general 

contextual purposes only, because none of the samples was 

collected for regulatory compliance purposes. The following 

summary descriptions of median concentrations represent 

the median of measurement detections at or greater than the 

reporting level.

Physical Properties

Values of physical properties (dissolved oxygen, 

pH, specific conductance, BOD, total dissolved solids, 

suspended solids, and alkalinity) varied among sites and 

between periodic and stormflow samples (table 4 at end of 

report). Median dissolved oxygen concentrations measured 

in periodic samples ranged from 6.2 milligrams per liter 

(mg/L) (Leon 35 site) to 10 mg/L (SAR 410 site). The 

median pH concentrations ranged from 7.4 standard units 

(SAR Elmendorf site, stormflow samples) to 8.0 standard 

units (SAR 410, Medina, and SAR Elmendorf sites, periodic 

samples). The median specific conductance concentrations 
8 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

ranged from 326 microsiemens per centimeter (μS/cm) (Leon 

35 site, stormflow samples) to 955 μS/cm (Salado 13 site, 

periodic samples). The median BOD concentrations ranged 

from 0.9 mg/L (Leon 35 site, periodic samples) to 10.5 

mg/L (SAR 410 site, stormflow samples). Median dissolved 

solid concentrations ranged from 182 mg/L (SAR 410 site, 

stormflow samples) to 558 mg/L (Salado 13 site, periodic 

samples). The median suspended solid concentrations ranged 

from 8 mg/L (SAR 410 site, periodic samples) to 828 mg/L 

(Medina site, stormflow samples). The median alkalinity 

concentrations ranged from 84 mg/L (SAR 410 site, stormflow 

samples) to 280 mg/L (Salado 13 site, periodic samples). 

Major Ions

The median concentrations of selected major ions 

(calcium, magnesium, potassium, sodium, chloride, and 

sulfate) were generally greater in periodic samples as 

compared to stormflow samples. The exceptions were for 

potassium concentrations measured in samples collected from 

the Salado 13 and Medina sites. The median concentrations 

of major ions varied among sites in periodic and stormflow 

samples; however, stormflow samples at the SAR Elmendorf 

site were generally greater as compared to the other sites. 

The median calcium concentrations ranged from 35.0 mg/L 

(SAR 410 site, stormflow samples) to 110 mg/L (Salado 

13 site, periodic samples). Median magnesium concentrations 

ranged from 4.19 mg/L (Leon 35 site, stormflow samples) 

to 14.0 mg/L (Leon 35 site, periodic samples). Median 

potassium concentrations ranged from 2.10 mg/L (SAR 410 

site, periodic samples) to 6.70 mg/L (SAR Elmendorf site, 

periodic samples). Median sodium concentrations ranged 

from 13.2 mg/L (SAR 410 site, stormflow samples) to 

74.0 mg/L (Salado 13, periodic samples). Median chloride 

concentrations ranged from 16.0 mg/L (Leon 35 site, 

stormflow samples) to 92.0 mg/L (SAR Elmendorf site, 

periodic samples). Median sulfate concentrations ranged from 

25.0 mg/L (SAR 410 site, stormflow samples) to 92.0 mg/L 

(Leon 35 site, periodic samples).

Nutrients

Median concentrations of nutrients were compared 

among sites, as well as between periodic and stormflow 

samples. Nutrient concentrations of filtered nitrogen and 

phosphorus constituents were measured in as many as 19 of 

the periodic samples and 13 of the stormflow samples. Median 

concentrations for filtered ammonia, nitrate plus nitrite, 

organic nitrogen, and phosphorus generally were greater 

in periodic samples collected from the Medina and SAR 

Elmendorf sites as compared to samples collected from the 

other sites (fig. 4, table 4). The same pattern of greater median 

concentrations at the Medina and SAR Elmendorf sites is 

also present in the stormflow samples, with the exception of 

organic nitrogen. 

Median concentrations of ammonia in periodic 

samples at each site were slightly less than the associated 

median concentrations in stormflow samples, with the 

exception of the Medina site. The spread in the ammonia 

concentrations at the Medina site during periodic sampling 

is notably greater than the other the sites. Conversely, 

median concentrations of nitrate plus nitrite at each site were 

greater in the periodic samples as compared to the stormflow 

samples (fig. 4). A consistent pattern for organic nitrogen 

and phosphorus between periodic and stormflow samples was 

not present. 

Trace Elements

Median concentrations of unfiltered trace elements 

varied among the sites and between periodic and stormflow 

samples (fig. 5, table 4). For example, median concentrations 

of chromium were greater in stormflow samples collected 

from the Leon 35 site and lesser in samples collected from the 

Salado 13 site. Median concentrations of lead in stormflow 

samples, however, were greater at the SAR 410 site and 

lesser in stormflow samples from the Medina site. Median 

concentrations of arsenic were generally similar in stormflow 

samples collected at each of the five sites (fig. 5).

Median trace element concentrations measured in 

periodic samples were generally less than concentrations 

measured in stormflow samples (figs. 2 and 5, tables 2 and 4). 

For example, the SAR 410 site (with the largest percentage of 

developed land cover) and the Medina site (with the largest 

percentage of undeveloped land cover) both exhibited greater 

median concentrations in the stormflow samples as compared 

to the respective periodic samples. 

Comparing trace element concentrations to TCEQ 

standards indicated that all measured values were less than 

the TCEQ standards, with the exception of arsenic in one 

stormflow sample at the Leon 35 site, and lead in both 

periodic and stormflow samples at several sites (fig. 5, table 4; 

Texas Commission on Environmental Quality, 2010). The 

concentrations reported here represent unfiltered samples, 

whereas the TCEQ standards for some constituents represent 

concentrations for filtered samples. Some trace elements 

were likely bound to particulates in the water column. 

Although trace element concentrations were detected by 

using the analytical methods described in this report, these 

trace elements might or might not be available to biological 

species and subsequent food webs (commonly referred to as 

“bioavailability”). Surface water that is extracted from a river 

typically undergoes several steps of filtration, sedimentation, 

and treatment before it is considered acceptable for drinking 

water purposes. Thus, comparisons of unfiltered sample 

concentrations to TCEQ standards were for contextual 

purposes only. 
Water-Quality Data 9

Figure 4. Water-quality data of selected nutrients in filtered periodic and stormflow samples in the study area, Bexar County, Texas, 

1992–98 (table 1). A, Ammonia, as nitrogen. B, Nitrate plus nitrite, as nitrogen. C, Organic nitrogen. D, Phosphorus, as phosphorus.

Site Site

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Concentration, in milligrams per liter Concentration, in milligrams per liter

0

0.5

1

0

5

10

15

0

0.5

1

0

0.5

1

1.5

2

2.5

3

3.5

Periodic Stormflow Periodic Stormflow

Periodic Stormflow Periodic Stormflow

EXPLANATION

Value less than the laboratory reporting level

Value equal to or greater than the laboratory reporting level

 Leon 35 site (USGS station 08181480)—Leon Creek at Interstate Highway 35, San Antonio, Tex.

 SAR 410 site (USGS station 08178565)—San Antonio River at Loop 410, San Antonio, Tex.

 Salado 13 site (USGS station 08178800)—Salado Creek at Loop 13, San Antonio, Tex.

 Medina site (USGS station 08181500)—Medina River at San Antonio, Tex.

 SAR Elmendorf site (USGS station 08181800)—San Antonio River near Elmendorf, Tex.

USGS, U.S. Geological Survey

A. Ammonia, filtered, as nitrogen B. Nitrate plus nitrite, filtered, as nitrogen

C. Organic nitrogen, filtered D. Phosphorus, filtered, as phosphorus
10 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Figure 5. Water-quality data of selected trace elements in unfiltered periodic and stormflow samples in the study area, Bexar County, 

Texas, 1992–98 (table 1). A, Cadmium. B, Chromium. C, Copper. D, Lead. E, Mercury. F, Arsenic. 

Site Site

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Leon 35

SAR 410

Salado 13

Medina

SAR Elmendorf

Concentration, in micrograms per liter (μg/L)

0

10

20

30

40

50

0

1

2

3

4

5

6

7

8

9

10

0

10

20

30

40

0

10

20

30

40

50

60

70

80

90

100

110

0

0.5

1

1.5

2

0

2

4

6

8

10

12

14

16

Periodic Stormflow Periodic Stormflow

Periodic Stormflow Periodic Stormflow

Periodic Stormflow Periodic Stormflow

Stormflow

EXPLANATION

Value less than the laboratory reporting level

Value equal to or greater than the laboratory reporting level

 Leon 35 site (USGS station 08181480)—Leon Creek at Interstate Highway 35, San Antonio, Tex.

 SAR 410 site (USGS station 08178565)—San Antonio River at Loop 410, San Antonio, Tex.

 Salado 13 site (USGS station 08178800)—Salado Creek at Loop 13, San Antonio, Tex.

 Medina site (USGS station 08181500)—Medina River at San Antonio, Tex.

 SAR Elmendorf site (USGS station 08181800)—San Antonio River near Elmendorf, Tex.

USGS, U.S. Geological Survey

TCEQ standards are Texas Commission on Environmental Quality surface water standards (Texas Commission on Environmental Quality, 2010),

in micrograms per liter (μg/L) 

E. Mercury, unfiltered F. Arsenic, unfiltered, TCEQ standard = 10 μg/L

A. Cadmium, unfiltered, TCEQ standard = 5 μg/L B. Chromium, unfiltered

C. Copper, unfiltered D. Lead, unfiltered, TCEQ standard = 1.15 μg/L 
References 11

Organic Compounds

Organic compounds were measured in the periodic and 

stormflow samples. Most of the concentrations of analyzed 

organic compounds were less than the laboratory reporting 

levels (appendixes 1 and 2). Of the organic compounds 

greater than the laboratory reporting level, a few of the 

measured concentrations were different among sites and 

between periodic and stormflow samples. For example, 

bromodichloromethane was less than the laboratory reporting 

level in the periodic or stormflow samples collected from 

the Leon 35, SAR 410, and Salado 13 sites but was equal 

to or greater than the laboratory reporting level in some the 

periodic and stormflow samples collected from the Medina 

site and all of the samples collected from the SAR Elmendorf. 

This compound was historically used as a solvent and fire 

retardant and is associated with chlorinated water treatment 

processes (National Institute of Health, 2011). Conversely, 

tetrachloroethene (PCE), which is commonly associated with 

industrial practices such as commercial dry-cleaning, metal 

cleaning, and chemical intermediates (National Institute of 

Health, 2011), was detected in 8 out of the 10 of the periodic 

samples and in 1 out of the 5 stormflow samples at the Leon 

35 site but was not detected in samples collected from any 

of the other sites (table 4). Diazinon, a pesticide, was most 

frequently detected in periodic samples at the Salado 13 

site (6 out of 14) and in stormflow samples at the SAR 410 

and Salado 13 sites (3 out of 4 and 3 out of 6, respectively). 

Note that the SAR 410 and Salado 13 sites had the lowest 

cultivated land-cover percentages of the watersheds in this 

study (table 2). Oil and grease were detected more often in the 

stormflow samples as compared to periodic samples at all of 

the sites. 

All of the organic compound concentrations were less 

than the respective TCEQ standards, with the exception of 

chlordane, which was measured in 4 out of 12 stormflow 

samples collected from the SAR 410 site, and bis(2-

ethylhexyl) phthalate, which was measured in 1 out of 5 

stormflow samples collected at the Leon 35 site (table 4; 

Texas Commission on Environmental Quality, 2010). 

References

Buchanan, T.J., and Somers, W.P., 1969, Discharge 

measurements at gaging stations: U.S. Geological Survey 

Techniques of Water Resource Investigation, book 3, chap. 

A8, 65 p. (Also available at http://pubs.usgs.gov/twri/

twri3a8/.)

Childress, C.J.O., Forman, W.T., Connor, B.F., and Maloney, 

T.J., 1999, New reporting procedures based on long-term 

method detection levels and some considerations for 

interpretations of waterquality data provided by the U.S. 

Geological Survey National Water Quality Laboratory: 

U.S. Geological Survey Open-File Report 99–193, 19 p.

Clesceri, L.S., Greenberg, A.E., and Eaton, A.D., eds., 

1998, Standard methods for the examination of water and 

wastewater (20th ed.): Washington, D.C., American Public 

Health Association [variously paged].

Delzer, G.C., and McKenzie, S.W., 1999, Five-day 

biochemical oxygen demand: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chap. A7, section 7.0. (Also available at http://water.usgs.

gov/owq/FieldManual/chap7.2.pdf.)

Dubrovsky, N.M., Burow, K.R., Clark, G.M., Gronberg, J.M., 

Hamilton, P.A., Hitt, K.J., Mueller, D.K., Munn, M.D., 

Nolan, B.T., Puckett, L.J., Rupert, M.G., Short, T.M., Spahr, 

N.E., Sprague, L.A., and Wilber, W.G., 2010, The quality of 

our Nation’s waters—Nutrients in the Nation’s streams and 

groundwater, 1992–2004: U.S. Geological Survey Circular 

1350, 174 p.

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 OpenFile Report 93–125, p. 27–45. 

Fishman, M.J., and Friedman, L.C., eds., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 545 p.

Garbarino, J.R., and Struzeski, T.M., 1998, Methods of 

analysis by the U.S. Geological Survey National Water 

Quality Laboratory—Determination of elements in wholewater digests using inductively coupled plasma-optical 

emission spectrometry and inductively coupled plasmamass spectrometry: U.S. Geological Survey Open-File 

Report 98–165, 101 p. 

National Institute of Health, 2011, 12th Report on carcinogens: 

U.S. Department of Health and Human Services, 507 p., 

accessed on August 10, 2012, at http://ntp.niehs.nih.gov/ntp/

roc/twelfth/roc12.pdf. 

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 OpenFile Report 92–146, 39 p. 

Rantz, S.E., and others, 1982a, Measurement and computation 

of streamflow—Volume 1. Measurement of stage and 

discharge: U.S. Geological Survey Water-Supply Paper 

2175, 284 p., accessed March 17, 2011, at http://pubs.usgs.

gov/wsp/wsp2175/pdf/WSP2175_vol1a.pdf.

Rantz, S.E., and others, 1982b, Measurement and computation 

of streamflow—Volume 2. Computation of discharge: 

U.S. Geological survey Water-Supply Paper 2175, 631 p., 

accessed March 17, 2011, at http://pubs.usgs.gov/wsp/

wsp2175/pdf/WSP2175_vol2a.pdf.
12 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

San Antonio River Authority, 2012, San Antonio River Basin 

Clean Rivers Program: San Antonio River Authority, 

accessed on July 9, 2012, at http://www.sara-tx.org/

public_resources/library/documents/water_quality_

monitoring/2012_Watershed_Characterization__Reportfinal.pdf.

Texas Commission on Environmental Quality, 2010, Texas 

Surface Water Quality Standards: accessed August 30, 

2012, at http://info.sos.state.tx.us/pls/pub/readtac$ext.

TacPage?sl=R&app=9&p_dir=&p_rloc=&p_tloc=&p_

ploc=&pg=1&p_tac=&ti=30&pt=1&ch=307&rl=6.

Turnipseed, D.P., and Sauer, V.B., 2010, Discharge 

measurements at gaging stations: U.S. Geological Survey 

Techniques and Methods, book 3, chap. A8, 87 p. (Also 

available at http://pubs.usgs.gov/tm/tm3-a8/.)

U.S. Census Bureau, 1996, Land, area, population, and density 

for places in Texas—1990: U.S. Census Bureau, accessed 

August 10, 2012, at http://www.census.gov/population/

www/censusdata/files/places/48tx.txt.

U.S. Census Bureau, 2001a, County and City Data Book: 

2000, Table C-1: U.S. Census Bureau, accessed 

November 29, 2012, at http://www.census.gov/statab/ccdb/

cit1010r.txt.

U.S. Census Bureau, 2001b, Population change and 

distribution 1990 to 2000: U.S. Census Bureau, accessed 

August 10, 2012, at http://www.census.gov/prod/2001pubs/

c2kbr01-2.pdf.

U.S. Environmental Protection Agency, 1984, Method 608: 

Code of Federal Regulations, v. 49, no. 209, p. 89–104.

U.S. Environmental Protection Agency, 1999, Method 1664, 

Revision A, n-Hexane extractable material (HEM; oil 

and grease) and silica gel treated n-hexane extractable 

material (SGT-HEM; non-polar material) by extraction 

and gravimetry: Washington, D.C., Office of Water, EPA821-R-98-002, 23 p.

U.S. Environmental Protection Agency, 2012a, Summary 

of the Clean Water Act: U.S. Environmental Protection 

Agency, accessed July 9, 2012, at http://www.epa.gov/

lawsregs/laws/cwa.html.

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Water Contaminants—National Primary Drinking Water 

Regulations: U.S. Environmental Protection Agency, 

accessed July 9, 2012, at http://water.epa.gov/drink/

contaminants/index.cfm.

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National Water Information System, accessed October 15, 

2012, at http://waterdata.usgs.gov/tx/nwis/nwis.

U.S. Geological Survey, variously dated, National field manual 

for the collection of water-quality data: U.S. Geological 

Survey Techniques of Water-Resources Investigations, 

book 9, chaps. A1–A9.

Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., 

Wylie, B.K., and Van Driel, J.N., 2001, Completion of the 

1990s National Land Cover Data Set for the conterminous 

United States: Photogrammetric Engineering and Remote 

Sensing, v. 67, p. 650–662.

Wells, F.C, Gibbons, W.J., and Dorsey, M.E., 1990, Guidelines 

for collection and field analysis of water-quality samples 

from streams in Texas: U.S. Geological Survey Open-File 

Report 90–127, 79 p.

Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., 

1983, Methods for the determination of organic substances 

in water and fluvial sediments, in U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 5, 

chap. A3: U.S. Geological Survey Open-File Report 

82–1004, 173 p.
Table 1 13

Table 1. Data-collection sites in the study area, Bexar County, Texas.

[dd, degrees; mm, minutes; ss, seconds; cfs, cubic feet per second]

U.S. 

Geological 

Survey 

station 

number

Site 

identifier

U.S. Geological Survey 

station name

Latitude

(dd mm ss)

Longitude

(dd mm ss)

Drainage 

area

(square 

miles)

Daily mean 

streamflow, 

1992–98

(cfs)

08181480 Leon 35 Leon Creek at Interstate Highway 35, San Antonio, Tex. 29°19’47” 98°35’02” 207 48

08178565 SAR 410 San Antonio River at Loop 410, San Antonio, Tex. 29°19’19” 98°27’00” 115 142

08178800 Salado 13 Salado Creek at Loop 13, San Antonio, Tex. 29°21’25” 98°24’45” 185 64

08181500 Medina Medina River at San Antonio, Tex. 29°15’50” 98°29’26” 1,300 376

08181800 SAR Elmendorf San Antonio River near Elmendorf, Tex. 29°13’19” 98°21’20” 1,741 671

Table 1
14 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 2. Land-cover type and percentage of occurrence in the study area, Bexar County, Texas, 1992.

[dd, degrees; mm, minutes; ss, seconds; --, not applicable; %, percent]

U.S. Geological 

Survey station 

number

Site 

identifier

1992 Land cover category (percent)1

Developed

Low intensity 

residential

High intensity 

residential

Commercial/industrial/

transportation

08181480 Leon 35 8.7% 6.4% 7.0%

08178565 SAR 410 16.5% 41.4% 20.9%

08178800 Salado 13 10.9% 12.6% 10.3%

08181500 Medina 2.5% 1.6% 1.7%

08181800 SAR Elmendorf 4.4% 5.8% 4.3%

U.S. Geological 

Survey station 

number

Site 

identifier

1992 Land cover category (percent)1

Undeveloped

Open 

water

Bare 

rock/

sand/

clay

Quarries/

strip 

mines/

gravel 

pits

TransitionalDeciduous 

forest

Evergreen 

forest

Mixed 

forest

ShrublandGrasslands/

herbaceous

Emergent 

herbaceous 

wetlands

08181480 Leon 35 0.2% 0.4% 0.7% 0.1% 10.8% 38.6% -- 7.4% 7.4% 0.0%

08178565 SAR 410 0.2% 0.1% 0.9% -- 3.4% 4.7% -- 2.7% 0.6% 0.0%

08178800 Salado 13 0.3% 0.1% 1.2% -- 9.0% 36.6% -- 4.6% 6.7% 0.0%

08181500 Medina 1.0% 0.6% 0.3% 0.0% 7.5% 41.8% 0.0% 15.0% 10.1% 0.0%

08181800 SAR Elmendorf 1.0% 0.5% 0.4% 0.0% 7.4% 35.7% 0.0% 13.3% 8.6% 0.1%

U.S. Geological 

Survey station 

number

Site identifier

1992 Land cover category (percent)1 Summary

Culitvated 1992 Land cover category (percent)1

Pasture/

hay

Row 

crops

Small 

grains

Urban/

recreational 

grasses

Total

developed

Total

undeveloped

Total

cultivated

08181480 Leon 35 3.8% 1.0% 4.4% 3.1% 22.1% 65.6% 12.3%

08178565 SAR 410 2.2% 0.0% 0.2% 6.1% 78.8% 12.6% 8.6%

08178800 Salado 13 2.7% 0.0% 0.5% 4.4% 33.8% 58.5% 7.7%

08181500 Medina 9.2% 5.4% 2.4% 0.7% 5.9% 76.3% 17.8%

08181800 SAR Elmendorf 10.0% 4.9% 1.9% 1.6% 14.5% 67.1% 18.3%

1

Land cover categories modified from National Land Cover Dataset, 1992. 

Table 2
Table 3 15

Table 3. Dates of periodic and stormflow sampling events in the study area, Bexar County, Texas, 1992–98.

[PS, periodic sample; SF, stormflow sample; green shading indicates periodic sample collected; grey shading indicates stormflow sample collected]

Sampling 

date

U.S. Geological 

Survey station 

number 08181480

Leon Creek at 

Interstate Highway 35, 

San Antonio, Tex.

(Leon 35)

U.S. Geological 

Survey station 

number 08178565

San Antonio River at 

Loop 410, 

San Antonio, Tex.

(SAR 410)

U.S. Geological 

Survey station 

number 08178800

Salado Creek at 

Loop 13, 

San Antonio, Tex.

(Salado 13)

U.S. Geological 

Survey station 

number 08181500

Medina River at 

San Antonio, Tex.

(Medina)

U.S. Geological 

Survey station 

number 08181800

San Antonio River near 

Elmendorf, Tex.

(SAR Elmendorf)

12/2–12/3/1992 PS PS PS PS PS

2/22–2/24/1993 PS PS PS PS PS

4/12–4/14/1993 PS PS PS PS PS

5/5/1993 SF

5/11–5/13/1993 PS PS PS PS PS

8/2–8/6/1993 PS PS PS PS PS

8/16–8/17/1993 PS PS PS PS PS

9/20–9/21/1993 PS PS PS PS PS

10/5–10/7/1993 PS PS PS PS PS

10/20/1993 SF

11/15–11/18/93 PS PS PS PS PS

12/20–12/22/1993 PS PS PS PS PS

2/2–2/4/1994 PS PS PS PS PS

2/14–2/16/1994 PS PS PS PS PS

3/15/1994 SF SF

4/28–4/29/1994 SF SF SF

5/13–5/14/1994 SF SF

5/31–6/3/1994 PS PS PS PS PS

7/20–7/22/1994 PS PS PS PS PS

9/6–9/14/1994 PS PS PS PS PS

9/8/1994 SF SF

10/18/1994 SF SF

11/1–11/9/1994 PS PS PS PS PS

12/5–12/7/1995 PS PS PS PS PS

12/28/1994 SF SF SF

2/13–2/22/1995 PS PS PS PS PS

5/30/1995 SF SF

6/11/1995 SF SF SF SF SF

8/15–8/18/95 PS PS PS PS PS

7/26/1996 SF

9/15/1996 SF SF SF

11/24/1996 SF SF

2/12/1997 SF SF SF

3/11/1997 SF

4/1–4/3/1997 SF SF SF SF SF

4/26/1997 SF SF SF

10/10/1997 SF SF

12/20/1997 SF SF

1/6/1998 SF

3/16/1998 SF

9/11/1998 SF SF

Number of periodic 

sampling events 19 19 19 19 19

Number of stormflow 

sampling events 9 12 11 7 10

Table 3
16 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Streamflow, cubic feet per second 19/19 0.47 40 11 10/10 119 802 311

Physical properties

Dissolved oxygen, water, unfiltered, 

milligrams per liter

19/19 3.7 12.5 6.2 0/0 -- -- --

Dissolved oxygen, water, unfiltered, percent 

of saturation

19/19 39 137 74 0/0 -- -- --

pH, water, unfiltered, laboratory, standard 

units

19/19 7.5 8.3 7.9 10/10 7.4 8.0 7.6

Specific conductance, water, unfiltered, 

laboratory, microsiemens per centimeter 

at 25 degrees Celsius

19/19 736 911 785 10/10 210 448 326

Temperature, water, degrees Celsius 19/19 13.0 28.0 22.0 0/0 -- -- --

Biochemical oxygen demand, water, 

unfiltered, 5 days at 20 degrees Celsius, 

milligrams per liter

18/18 0.2 7.7 0.9 8/8 3.9 28.0 5.2

Chemical oxygen demand, high level, 

water, unfiltered, milligrams per liter

4/10 10 20 20 10/10 30 80 50

Dissolved solids dried at 180 degrees 

Celsius, water, filtered, milligrams per 

liter

10/10 447 549 491 10/10 112 265 189

Suspended solids, water, unfiltered, 

milligrams per liter

17/19 1 56 9 10/10 123 1,560 692

Alkalinity, water, filtered, fixed endpoint 

(pH 4.5) titration, field, milligrams per 

liter as calcium carbonate

19/19 210 280 240 10/10 62 130 91

Major ions

Calcium, water, filtered, milligrams per liter 19/19 65.0 110 85.0 10/10 25.0 51.0 35.5

Magnesium, water, filtered, milligrams per 

liter

19/19 11.0 18.0 14.0 10/10 2.20 6.00 4.19

Potassium, water, filtered, milligrams per 

liter

19/19 2.80 5.90 3.20 10/10 3.05 4.80 3.65

Sodium, water, filtered, milligrams per liter 19/19 45.0 85.0 65.0 10/10 7.30 29.0 15.9

Chloride, water, filtered, milligrams per liter 19/19 39.0 83.0 47.0 10/10 6.70 26.8 16.0

Sulfate, water, filtered, milligrams per liter 19/19 75.0 130 92.0 10/10 9.10 46.0 27.5

Nutrients

Ammonia, water, filtered, milligrams per 

liter as nitrogen

16/18 0.020 0.180 0.040 8/9 0.030 0.110 0.060

Nitrate plus nitrite, water, filtered, 

milligrams per liter as nitrogen

17/18 0.51 2.30 1.50 9/9 0.40 0.79 0.52

Organic nitrogen, water, unfiltered, 

milligrams per liter

7/9 0.16 0.55 0.22 8/9 0.27 3.6 1.1

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.

[n, number; median values represent median of detected values]

Table 4
Table 4 17

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Phosphorus, water, filtered, milligrams per 

liter as phosphorus

18/19 0.03 0.78 0.08 9/9 0.07 0.95 0.12

Total nitrogen, water, unfiltered, milligrams 

per liter

7/9 1.5 2.5 2.3 9/9 0.72 4.5 1.6

Trace elements

Beryllium, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Cadmium, water, unfiltered, micrograms 

per liter

4/10 1.0 2.0 1.5 10/10 1.0 4.0 2.0

Chromium, water, unfiltered, recoverable, 

micrograms per liter

8/10 1.1 17.0 2.4 10/10 11.0 42.5 20.5

Copper, water, unfiltered, recoverable, 

micrograms per liter

10/10 1.0 6.0 2.0 10/10 8.0 29.2 14.0

Lead, water, unfiltered, recoverable, 

micrograms per liter

7/10 1.0 2.0 1.0 10/10 11.0 64.0 30.5

Mercury, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.1 0.1 0.1 3/10 0.1 0.2 0.1

Nickel, water, unfiltered, recoverable, 

micrograms per liter

10/10 2.0 33.0 13.0 10/10 5.8 46.7 13.6

Silver, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 4/10 1.0 2.8 1.8

Thallium, water, unfiltered, micrograms per 

liter

0/10 -- -- -- 0/6 -- -- --

Zinc, water, unfiltered, recoverable, 

micrograms per liter

8/10 10 30 15 9/10 40 230 100

Antimony, water, unfiltered, EPA contract, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

Arsenic, water, unfiltered, micrograms per 

liter

7/10 1 2 2 10/10 2 15 5

Cyanide, water, unfiltered, milligrams per 

liter

0/10 -- -- -- 0/10 -- -- --

Selenium, water, unfiltered, micrograms 

per liter

0/10 -- -- -- 0/10 -- -- --

Organic compounds

1,2,3-Trichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dibromo-3-chloropropane, water, 

unfiltered, recoverable, micrograms per 

liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dibromoethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
18 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

1,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,3-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,4-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

2,4,6-Trichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2,4-Dichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2,4-Dimethylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2-Methyl-4,6-dinitrophenol, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

4-Chloro-3-methylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

4-Nitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Acrylonitrile, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Aldrin, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

alpha-Endosulfan, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

alpha-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

beta-Endosulfan, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

beta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Bromomethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chlordane (technical), water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

cis-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

cis-Chlordane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

delta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Diazinon, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 1/4 0.20 0.20 0.20
Table 4 19

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Dieldrin, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 1/8 0.02 0.02 0.02

Endosulfan sulfate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Endrin aldehyde, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Endrin, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Heptachlor epoxide, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Heptachlor, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Hexachlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Lindane, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

p,p’-DDD, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

p,p’-DDE, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

p,p’-DDT, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Pentachlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Toxaphene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

trans-1,3-Dichloropropene, water, 

unfiltered, recoverable, micrograms per 

liter

0/10 -- -- -- 0/5 -- -- --

trans-Chlordane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1016, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1221, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1232, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1242, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1248, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

Aroclor 1254, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --
20 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Aroclor 1260, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/8 -- -- --

1,1,1,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1,1-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

1/10 0.2 0.2 0.2 0/5 -- -- --

1,1,2,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1,2-Trichloro-1,2,2-trifluoroethane, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

1,1,2-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2,3-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2,4-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

1,2,4-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 1/5 0.2 0.2 0.2

1,2-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

1,2-Diphenylhydrazine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

1,3,5-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,3-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

2,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

2,4-Dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2,4-Dinitrotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2,6-Dinitrotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2-Chloroethyl vinyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
Table 4 21

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

2-Chloronaphthalene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2-Chlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

2-Chlorotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

2-Nitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

3,3’-Dichlorobenzidine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

4-Bromophenyl phenyl ether, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

4-Chlorophenyl phenyl ether, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

4-Chlorotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

4-Isopropyltoluene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

9H-Fluorene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Acenaphthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Acenaphthylene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Acrolein, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Anthracene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Benzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Benzo[a]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Benzo[a]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Benzo[b]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Benzo[ghi]perylene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Benzo[k]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --
22 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Benzyl n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Bis(2-chloroethoxy)methane, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

Bis(2-chloroethyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Bis(2-chloroisopropyl) ether, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

Bis(2-ethylhexyl) phthalate, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 1/5 10 10 10

Bromobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Bromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Bromodichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chrysene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

cis-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

5/10 0.4 0.5 0.4 2/5 0.2 0.5 0.4

Dibenzo[a,h]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Dibromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dibromomethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dichlorodifluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Diethyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Dimethyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --
Table 4 23

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Di-n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Di-n-octyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Ethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Fluoranthene, water, unfiltered, recoverable, 

micrograms per liter

1/9 6.00 6.00 6.00 0/5 -- -- --

Hexachlorobutadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

Hexachlorocyclopentadiene, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

Hexachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Indeno[1,2,3-cd]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Isophorone, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Isopropylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Methyl tert-butyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Naphthalene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/6 -- -- --

n-Butylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Nitrobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

N-Nitrosodimethylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

N-Nitrosodi-n-propylamine, water, 

unfiltered, recoverable, micrograms per 

liter

0/9 -- -- -- 0/5 -- -- --

N-Nitrosodiphenylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

n-Propylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Oil and grease, water, unfiltered, freon 

extraction, gravimetric, recoverable, 

milligrams per liter

0/10 -- -- -- 1/9 1 1 1

Organic carbon, water, unfiltered, 

milligrams per liter

18/19 0.3 4.1 2.8 10/10 9.6 30.0 18.5
24 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181480

Leon Creek at Interstate Highway 35, San Antonio, Tex.

(Leon 35)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum

value

Median 

value

Phenanthrene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Phenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Phenolic compounds, water, unfiltered, 

recoverable, micrograms per liter

5/9 1 5 2 4/10 1 6 2

Pyrene, water, unfiltered, recoverable, 

micrograms per liter

1/9 5.00 5.00 5.00 0/5 -- -- --

sec-Butylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Styrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

tert-Butylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Tetrachloroethene, water, unfiltered, 

recoverable, micrograms per liter

8/10 0.2 0.6 0.3 1/5 0.5 0.5 0.5

Tetrachloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Toluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

trans-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Tribromomethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trichloroethene, water, unfiltered, 

recoverable, micrograms per liter

9/10 0.2 0.6 0.4 1/5 0.6 0.6 0.6

Trichlorofluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 1/5 0.6 0.6 0.6

Trichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trihalomethanes, water, unfiltered, 

maximum summation, micrograms per 

liter

0/10 -- -- -- 0/5 -- -- --

Vinyl chloride, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Xylene (all isomers), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
Table 4 25

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Streamflow, cubic feet per second 19/19 11 266 57 13/13 417 3,650 1,160

Physical properties

Dissolved oxygen, water, unfiltered, milligrams 

per liter

19/19 7.6 17.6 10.0 0/0 -- -- --

Dissolved oxygen, water, unfiltered, percent of 

saturation

19/19 88 175 126 0/0 -- -- --

pH, water, unfiltered, laboratory, standard units 19/19 7.7 8.2 8.0 13/13 6.9 7.9 7.5

Specific conductance, water, unfiltered, 

laboratory, microsiemens per centimeter at 25 

degrees Celsius

19/19 460 643 552 13/13 191 459 345

Temperature, water, degrees Celsius 19/19 14.0 32.0 22.5 0/0 -- -- --

Biochemical oxygen demand, water, unfiltered, 5 

days at 20 degrees Celsius, milligrams per liter

18/18 0.5 2.1 1.1 12/12 7.7 25.0 10.5

Chemical oxygen demand, high level, water, 

unfiltered, milligrams per liter

4/10 10 20 20 12/13 20 160 70

Dissolved solids dried at 180 degrees Celsius, 

water, filtered, milligrams per liter

10/10 262 367 306 13/13 100 252 182

Suspended solids, water, unfiltered, milligrams 

per liter

10/10 1 28 8 13/13 82 1,100 560

Alkalinity, water, filtered, fixed endpoint (pH 4.5) 

titration, field, milligrams per liter as calcium 

carbonate

19/19 120 240 190 13/13 59 110 84

Major ions

Calcium, water, filtered, milligrams per liter 19/19 48.0 76.0 67.0 13/13 22.1 42.2 35.0

Magnesium, water, filtered, milligrams per liter 19/19 12.0 20.0 17.0 13/13 1.97 9.30 5.40

Potassium, water, filtered, milligrams per liter 19/19 1.20 3.60 2.10 13/13 2.10 4.70 3.43

Sodium, water, filtered, milligrams per liter 19/19 17.0 47.0 26.0 13/13 4.72 27.0 13.2

Chloride, water, filtered, milligrams per liter 18/18 24.0 62.0 35.5 13/13 5.58 38.0 17.0

Sulfate, water, filtered, milligrams per liter 18/18 28.0 67.0 42.5 13/13 8.95 53.0 25.0

Nutrients

Ammonia, water, filtered, milligrams per liter as 

nitrogen

16/18 0.010 0.060 0.030 7/13 0.070 0.160 0.100

Nitrate plus nitrite, water, filtered, milligrams per 

liter as nitrogen

17/18 0.48 1.90 1.60 13/13 0.06 1.20 0.59

Organic nitrogen, water, unfiltered, milligrams 

per liter

6/10 0.15 0.34 0.25 7/13 0.63 4.3 2.1

Phosphorus, water, filtered, milligrams per liter 

as phosphorus

7/19 0.010 0.040 0.02 12/13 0.050 0.110 0.065

Total nitrogen, water, unfiltered, milligrams per 

liter

6/10 0.99 2.0 1.7 13/13 1.4 4.9 2.7
26 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Trace elements

Beryllium, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/13 -- -- --

Cadmium, water, unfiltered, micrograms per liter 0/10 -- -- -- 1/13 1.0 1.0 1.0

Chromium, water, unfiltered, recoverable, 

micrograms per liter

9/10 2.0 14.0 3.0 12/13 3.7 25.0 11.7

Copper, water, unfiltered, recoverable, 

micrograms per liter

7/10 1.0 4.0 1.0 13/13 8.7 32.0 16.6

Lead, water, unfiltered, recoverable, micrograms 

per liter

6/10 1.0 2.0 1.0 13/13 10.0 97.0 61.0

Mercury, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/13 0.1 0.1 0.1

Nickel, water, unfiltered, recoverable, 

micrograms per liter

7/10 1.0 4.0 2.0 13/13 3.4 19.0 8.6

Silver, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/13 -- -- --

Thallium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/4 -- -- --

Zinc, water, unfiltered, recoverable, micrograms 

per liter

4/10 10 30 15 13/13 40 280 170

Antimony, water, unfiltered, EPA contract, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Arsenic, water, unfiltered, micrograms per liter 5/10 1 2 1 13/13 2 8 4

Cyanide, water, unfiltered, milligrams per liter 0/10 -- -- -- 0/13 -- -- --

Selenium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/13 -- -- --

Organic compounds

1,2,3-Trichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromo-3-chloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromoethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,4-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4,6-Trichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 27

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

2,4-Dichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dimethylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Methyl-4,6-dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chloro-3-methylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acrylonitrile, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Aldrin, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

alpha-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

alpha-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

beta-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

beta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Bromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chlordane (technical), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 4/12 0.1 0.1 0.1

cis-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

cis-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

delta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Diazinon, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 3/4 0.10 0.30 0.20

Dieldrin, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/12 0.03 0.03 0.03

Endosulfan sulfate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Endrin aldehyde, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Endrin, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --
28 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Heptachlor epoxide, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Heptachlor, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Hexachlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Lindane, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.05 0.05 0.05 0/12 -- -- --

p,p’-DDD, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

p,p’-DDE, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/12 0.05 0.05 0.05

p,p’-DDT, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Pentachlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Toxaphene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

trans-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

trans-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1016, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1221, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1232, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1242, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1248, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1254, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Aroclor 1260, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

1,1,1,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,1-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,2,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 29

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

1,1,2-Trichloro-1,2,2-trifluoroethane, water, 

unfiltered, recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,2-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,3-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Diphenylhydrazine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3,5-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dinitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,6-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chloroethyl vinyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chloronaphthalene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --
30 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

3,3’-Dichlorobenzidine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Bromophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chlorophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Isopropyltoluene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

9H-Fluorene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acenaphthene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acenaphthylene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acrolein, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Anthracene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[a]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[a]pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[b]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[ghi]perylene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[k]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzyl n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroethoxy)methane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroethyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroisopropyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-ethylhexyl) phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 31

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Bromobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bromodichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chlorobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chrysene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

cis-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibenzo[a,h]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichlorodifluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Diethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dimethyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Di-n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Di-n-octyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Ethylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Fluoranthene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Hexachlorobutadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Hexachlorocyclopentadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
32 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Hexachloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Indeno[1,2,3-cd]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Isophorone, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Isopropylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Methyl tert-butyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Naphthalene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

n-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Nitrobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodimethylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodi-n-propylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodiphenylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

n-Propylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Oil and grease, water, unfiltered, freon extraction, 

gravimetric, recoverable, milligrams per liter

1/10 1 1 1 4/10 2 5 3

Organic carbon, water, unfiltered, milligrams per 

liter

10/10 1.2 7.8 2.2 13/13 9.4 96.0 23.0

Phenanthrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Phenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Phenolic compounds, water, unfiltered, 

recoverable, micrograms per liter

5/10 1 2 1 4/13 1 6 3

Pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

sec-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Styrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

tert-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 33

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar County, 

Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178565

San Antonio River at Loop 410, San Antonio, Tex.

(SAR 410)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Tetrachloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tetrachloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Toluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

trans-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tribromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichlorofluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trihalomethanes, water, unfiltered, maximum 

summation, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Vinyl chloride, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Xylene (all isomers), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
34 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Streamflow, cubic feet per second 19/19 4.3 48 11 12/12 190 1,520 552

Physical properties

Dissolved oxygen, water, unfiltered, milligrams 

per liter

19/19 3.3 10.6 7.1 0/0 -- -- --

Dissolved oxygen, water, unfiltered, percent of 

saturation

19/19 43 106 82 0/0 -- -- --

pH, water, unfiltered, laboratory, standard units 19/19 7.4 8.4 7.9 12/12 7.4 7.9 7.5

Specific conductance, water, unfiltered, 

laboratory, microsiemens per centimeter at 25 

degrees Celsius

19/19 339 1,190 955 12/12 267 689 382

Temperature, water, degrees Celsius 19/19 11.0 28.5 21.0 0/0 -- -- --

Biochemical oxygen demand, water, unfiltered, 

5 days at 20 degrees Celsius, milligrams per 

liter

17/17 0.5 8.0 1.0 11/11 4.0 27.0 6.4

Chemical oxygen demand, high level, water, 

unfiltered, milligrams per liter

7/10 10 30 20 12/12 10 80 50

Dissolved solids dried at 180 degrees Celsius, 

water, filtered, milligrams per liter

10/10 201 680 558 12/12 145 403 209

Suspended solids, water, unfiltered, milligrams 

per liter

17/19 5 87 11 12/12 122 1,040 410

Alkalinity, water, filtered, fixed endpoint (pH 

4.5) titration, field, milligrams per liter as 

calcium carbonate

19/19 110 320 280 12/12 76 210 120

Major ions

Calcium, water, filtered, milligrams per liter 19/19 41.0 120 110 12/12 30.0 73.0 45.8

Magnesium, water, filtered, milligrams per liter 19/19 4.30 23.0 16.0 12/12 2.90 13.0 5.95

Potassium, water, filtered, milligrams per liter 19/19 2.30 7.60 3.90 12/12 2.76 5.00 3.96

Sodium, water, filtered, milligrams per liter 19/19 19.0 110 74.0 12/12 7.60 48.0 20.3

Chloride, water, filtered, milligrams per liter 19/19 20.0 150 90.0 12/12 8.20 57.0 23.0

Sulfate, water, filtered, milligrams per liter 19/19 22.0 150 89.0 12/12 15.1 59.0 30.0

Nutrients

Ammonia, water, filtered, milligrams per liter 

as nitrogen

15/18 0.030 0.080 0.040 10/11 0.020 0.230 0.070

Nitrate plus nitrite, water, filtered, milligrams 

per liter as nitrogen

17/18 0.27 1.60 1.00 11/11 0.30 1.40 0.48

Organic nitrogen, water, unfiltered, milligrams 

per liter

6/10 0.16 0.45 0.26 10/11 0.33 2.3 1.4

Phosphorus, water, filtered, milligrams per liter 

as phosphorus

16/19 0.01 0.07 0.025 11/11 0.06 0.16 0.07

Total nitrogen, water, unfiltered, milligrams per 

liter

7/10 0.54 2.0 1.1 11/11 0.82 3.9 2.0
Table 4 35

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Trace elements

Beryllium, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Cadmium, water, unfiltered, micrograms per 

liter

0/10 -- -- -- 1/12 1.8 1.8 1.8

Chromium, water, unfiltered, recoverable, 

micrograms per liter

4/10 1.0 15.0 3.6 12/12 2.5 16.0 6.3

Copper, water, unfiltered, recoverable, 

micrograms per liter

7/10 1.0 9.0 1.0 12/12 3.7 16.9 9.5

Lead, water, unfiltered, recoverable, 

micrograms per liter

5/10 2.0 6.0 5.0 12/12 6.2 62.0 21.5

Mercury, water, unfiltered, recoverable, 

micrograms per liter

1/10 1.2 1.2 1.2 1/12 0.4 0.4 0.4

Nickel, water, unfiltered, recoverable, 

micrograms per liter

9/10 1.0 4.0 2.0 12/12 3.1 16.0 6.8

Silver, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/12 -- -- --

Thallium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/6 -- -- --

Zinc, water, unfiltered, recoverable, micrograms 

per liter

5/10 10 20 20 12/12 20 150 65

Antimony, water, unfiltered, EPA contract, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

Arsenic, water, unfiltered, micrograms per liter 9/10 1 3 1 12/12 2 8 4

Cyanide, water, unfiltered, milligrams per liter 0/10 -- -- -- 0/12 -- -- --

Selenium, water, unfiltered, micrograms per 

liter

0/10 -- -- -- 0/12 -- -- --

Organic compounds

1,2,3-Trichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dibromo-3-chloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dibromoethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,3-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,4-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --
36 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

2,4,6-Trichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2,4-Dichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2,4-Dimethylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2-Methyl-4,6-dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

4-Chloro-3-methylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

4-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Acrylonitrile, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Aldrin, water, unfiltered, recoverable, 

micrograms per liter

0/14 -- -- -- 0/11 -- -- --

alpha-Endosulfan, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/11 -- -- --

alpha-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

beta-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

beta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Bromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chlordane (technical), water, unfiltered, 

recoverable, micrograms per liter

0/14 -- -- -- 0/11 -- -- --

cis-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

cis-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

delta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Diazinon, water, unfiltered, recoverable, 

micrograms per liter

6/14 0.01 0.60 0.12 3/6 0.20 0.20 0.20

Dieldrin, water, unfiltered, recoverable, 

micrograms per liter

1/14 0.02 0.02 0.02 1/11 0.02 0.02 0.02

Endosulfan sulfate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Endrin aldehyde, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --
Table 4 37

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Endrin, water, unfiltered, recoverable, 

micrograms per liter

0/14 -- -- -- 0/11 -- -- --

Heptachlor epoxide, water, unfiltered, 

recoverable, micrograms per liter

0/14 -- -- -- 0/11 -- -- --

Heptachlor, water, unfiltered, recoverable, 

micrograms per liter

0/14 -- -- -- 0/11 -- -- --

Hexachlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Lindane, water, unfiltered, recoverable, 

micrograms per liter

0/14 -- -- -- 0/11 -- -- --

p,p’-DDD, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

p,p’-DDE, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

p,p’-DDT, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Pentachlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Toxaphene, water, unfiltered, recoverable, 

micrograms per liter

0/14 -- -- -- 0/11 -- -- --

trans-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

trans-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1016, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1221, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1232, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1242, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1248, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1254, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

Aroclor 1260, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/11 -- -- --

1,1,1,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1,1-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
38 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

1,1,2,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1,2-Trichloro-1,2,2-trifluoroethane, water, 

unfiltered, recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

1,1,2-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,1-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2,3-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2,4-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

1,2,4-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,2-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

1,2-Diphenylhydrazine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

1,3,5-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

1,3-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --

2,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

2,4-Dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2,4-Dinitrotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2,6-Dinitrotoluene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2-Chloroethyl vinyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

2-Chloronaphthalene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2-Chlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

2-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --
Table 4 39

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

2-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

3,3’-Dichlorobenzidine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

4-Bromophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

4-Chlorophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

4-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

4-Isopropyltoluene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

9H-Fluorene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Acenaphthene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Acenaphthylene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Acrolein, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Anthracene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Benzo[a]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzo[a]pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzo[b]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzo[ghi]perylene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzo[k]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Benzyl n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Bis(2-chloroethoxy)methane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Bis(2-chloroethyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Bis(2-chloroisopropyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --
40 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Bis(2-ethylhexyl) phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Bromobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Bromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/5 -- -- --

Bromodichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chlorobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Chrysene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

cis-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dibenzo[a,h]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Dibromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dibromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dichlorodifluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Dichloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Diethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Dimethyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Di-n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Di-n-octyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Ethylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Fluoranthene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Hexachlorobutadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/6 -- -- --
Table 4 41

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Hexachlorocyclopentadiene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Hexachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Indeno[1,2,3-cd]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Isophorone, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Isopropylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Methyl tert-butyl ether, water, unfiltered, 

recoverable, micrograms per liter

1/9 0.4 0.4 0.4 0/5 -- -- --

Naphthalene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/6 -- -- --

n-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Nitrobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

N-Nitrosodimethylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

N-Nitrosodi-n-propylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

N-Nitrosodiphenylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/6 -- -- --

n-Propylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Oil and grease, water, unfiltered, freon 

extraction, gravimetric, recoverable, 

milligrams per liter

0/10 -- -- -- 3/11 1 2 1

Organic carbon, water, unfiltered, milligrams 

per liter

18/19 2.4 8.1 4.2 12/12 8.3 30.0 16.0

Phenanthrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Phenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

Phenolic compounds, water, unfiltered, 

recoverable, micrograms per liter

6/10 1 3 2 2/12 1 3 2

Pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/6 -- -- --

sec-Butylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
42 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08178800

Salado Creek at Loop 13, San Antonio, Tex.

(Salado 13)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Styrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

tert-Butylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Tetrachloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Tetrachloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Toluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

trans-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Tribromomethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trichlorofluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trichloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Trihalomethanes, water, unfiltered, maximum 

summation, micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Vinyl chloride, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/5 -- -- --

Xylene (all isomers), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/5 -- -- --
Table 4 43

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Streamflow, cubic feet per second 19/19 64 435 117 7/7 123 1,990 788

Physical properties

Dissolved oxygen, water, unfiltered, milligrams 

per liter

19/19 6.4 10.6 7.5 0/0 -- -- --

Dissolved oxygen, water, unfiltered, percent of 

saturation

19/19 75 114 91 0/0 -- -- --

pH, water, unfiltered, laboratory, standard units 19/19 7.9 8.2 8.0 7/7 7.4 7.9 7.7

Specific conductance, water, unfiltered, 

laboratory, microsiemens per centimeter at 25 

degrees Celsius

19/19 751 992 912 7/7 417 979 600

Temperature, water, degrees Celsius 19/19 12.5 30.0 21.5 1/1 17.5 17.5 17.5

Biochemical oxygen demand, water, unfiltered, 5 

days at 20 degrees Celsius, milligrams per liter

18/18 0.7 6.2 1.3 6/6 5.6 9.3 6.4

Chemical oxygen demand, high level, water, 

unfiltered, milligrams per liter

8/10 10 30 20 6/7 30 150 50

Dissolved solids dried at 180 degrees Celsius, 

water, filtered, milligrams per liter

10/10 420 603 545 7/7 230 588 334

Suspended solids, water, unfiltered, milligrams 

per liter

10/10 1 73 30 7/7 62 2,710 828

Alkalinity, water, filtered, fixed endpoint (pH 4.5) 

titration, field, milligrams per liter as calcium 

carbonate

19/19 200 240 230 7/7 93 220 150

Major ions

Calcium, water, filtered, milligrams per liter 19/19 84.0 100 93.0 7/7 36.0 87.0 58.9

Magnesium, water, filtered, milligrams per liter 19/19 17.0 22.0 20.0 7/7 5.60 19.0 10.4

Potassium, water, filtered, milligrams per liter 19/19 3.60 18.0 5.50 7/7 4.60 6.80 5.50

Sodium, water, filtered, milligrams per liter 19/19 44.0 78.0 67.0 7/7 27.0 80.0 36.0

Chloride, water, filtered, milligrams per liter 19/19 54.0 99.0 81.0 7/7 32.0 99.0 45.0

Sulfate, water, filtered, milligrams per liter 19/19 64.0 110 90.0 7/7 35.0 98.0 59.0

Nutrients

Ammonia, water, filtered, milligrams per liter as 

nitrogen

18/18 0.020 0.770 0.145 7/7 0.030 0.354 0.130

Nitrate plus nitrite, water, filtered, milligrams per 

liter as nitrogen

18/18 2.80 10.0 7.80 7/7 1.70 8.80 2.60

Organic nitrogen, water, unfiltered, milligrams 

per liter

10/10 0.28 0.67 0.525 7/7 0.47 2.5 1.8

Phosphorus, water, filtered, milligrams per liter as 

phosphorus

19/19 0.38 1.7 0.65 7/7 0.16 1.4 0.3

Total nitrogen, water, unfiltered, milligrams per 

liter

10/10 4.8 11 8.2 7/7 2.3 9.5 4.5
44 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Trace elements

Beryllium, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Cadmium, water, unfiltered, micrograms per liter 0/10 -- -- -- 1/7 1.0 1.0 1.0

Chromium, water, unfiltered, recoverable, 

micrograms per liter

5/10 1.0 25.0 1.0 7/7 1.4 31.0 13.0

Copper, water, unfiltered, recoverable, 

micrograms per liter

10/10 1.0 3.0 2.0 7/7 3.0 19.0 12.0

Lead, water, unfiltered, recoverable, micrograms 

per liter

4/10 1.0 3.0 1.5 7/7 2.0 41.0 15.2

Mercury, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.2 0.2 0.2 0/7 -- -- --

Nickel, water, unfiltered, recoverable, micrograms 

per liter

9/10 2.0 11.0 3.0 7/7 3.0 31.0 10.8

Silver, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/7 -- -- --

Thallium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/4 -- -- --

Zinc, water, unfiltered, recoverable, micrograms 

per liter

10/10 10 40 20 7/7 50 110 60

Antimony, water, unfiltered, EPA contract, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Arsenic, water, unfiltered, micrograms per liter 4/10 1 5 2 6/7 3 9 6

Cyanide, water, unfiltered, milligrams per liter 0/10 -- -- -- 0/7 -- -- --

Selenium, water, unfiltered, micrograms per liter 1/10 1 1 1 0/7 -- -- --

Organic compounds

1,2,3-Trichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromo-3-chloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromoethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,4-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4,6-Trichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 45

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

2,4-Dichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dimethylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Methyl-4,6-dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chloro-3-methylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acrylonitrile, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Aldrin, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/7 -- -- --

alpha-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

alpha-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

beta-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

beta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Bromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chlordane (technical), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/7 -- -- --

cis-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

cis-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

delta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Diazinon, water, unfiltered, recoverable, 

micrograms per liter

2/10 0.10 0.20 0.15 2/4 0.10 0.20 0.15

Dieldrin, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Endosulfan sulfate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Endrin aldehyde, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Endrin, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/7 -- -- --
46 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Heptachlor epoxide, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Heptachlor, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Hexachlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Lindane, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.03 0.03 0.03 0/7 -- -- --

p,p’-DDD, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

p,p’-DDE, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

p,p’-DDT, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Pentachlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Toxaphene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

trans-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

trans-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1016, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1221, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1232, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1242, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1248, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1254, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

Aroclor 1260, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/7 -- -- --

1,1,1,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,1-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,2,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 47

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

1,1,2-Trichloro-1,2,2-trifluoroethane, water, 

unfiltered, recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

1,1,2-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,3-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Diphenylhydrazine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3,5-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dinitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,6-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chloroethyl vinyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chloronaphthalene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --
48 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

3,3’-Dichlorobenzidine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Bromophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chlorophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Isopropyltoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

9H-Fluorene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acenaphthene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acenaphthylene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Acrolein, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Anthracene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[a]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[a]pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[b]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[ghi]perylene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[k]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzyl n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroethoxy)methane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroethyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-chloroisopropyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bis(2-ethylhexyl) phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 49

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Bromobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Bromodichloromethane, water, unfiltered, 

recoverable, micrograms per liter

5/10 0.2 2.8 1.2 4/4 0.2 0.6 0.4

Chlorobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chrysene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

cis-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibenzo[a,h]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

4/10 0.5 1.8 1.2 2/4 0.3 0.4 0.4

Dibromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichlorodifluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Diethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dimethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Di-n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Di-n-octyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Ethylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Fluoranthene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Hexachlorobutadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Hexachlorocyclopentadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
50 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Hexachloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Indeno[1,2,3-cd]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Isophorone, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Isopropylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Methyl tert-butyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Naphthalene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

n-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Nitrobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodimethylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodi-n-propylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

N-Nitrosodiphenylamine, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

n-Propylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Oil and grease, water, unfiltered, freon extraction, 

gravimetric, recoverable, milligrams per liter

1/10 1 1 1 1/6 1 1 1

Organic carbon, water, unfiltered, milligrams per 

liter

10/10 3.0 12.0 3.7 7/7 6.1 57.0 20.0

Phenanthrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Phenol, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Phenolic compounds, water, unfiltered, 

recoverable, micrograms per liter

6/10 1 9 2 2/7 2 3 3

Pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

sec-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Styrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

tert-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --
Table 4 51

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181500

Medina River at San Antonio, Tex.

(Medina)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Tetrachloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tetrachloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Toluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/4 0.2 0.2 0.2

trans-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tribromomethane, water, unfiltered, recoverable, 

micrograms per liter

3/10 0.2 0.4 0.2 0/4 -- -- --

Trichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichlorofluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichloromethane, water, unfiltered, recoverable, 

micrograms per liter

8/10 0.2 5.4 0.7 4/4 0.3 1.3 0.8

Trihalomethanes, water, unfiltered, maximum 

summation, micrograms per liter

3/10 3.6 10.0 7.0 0/4 -- -- --

Vinyl chloride, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Xylene (all isomers), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
52 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Streamflow, cubic feet per second 19/19 138 2,680 320 10/10 920 2,260 1,940

Physical properties

Dissolved oxygen, water, unfiltered, milligrams 

per liter

19/19 6.4 10.3 7.7 0/0 -- -- --

Dissolved oxygen, water, unfiltered, percent of 

saturation

19/19 85 107 92 0/0 -- -- --

pH, water, unfiltered, laboratory, standard units 19/19 8.0 8.2 8.0 10/10 7.3 7.9 7.4

Specific conductance, water, unfiltered, 

laboratory, microsiemens per centimeter at 25 

degrees Celsius

19/19 764 995 921 10/10 427 666 585

Temperature, water, degrees Celsius 19/19 15.8 29.0 23.8 0/0 -- -- --

Biochemical oxygen demand, water, unfiltered, 5 

days at 20 degrees Celsius, milligrams per liter

18/18 0.6 2.4 1.2 9/9 0.8 15.0 7.7

Chemical oxygen demand, high level, water, 

unfiltered, milligrams per liter

9/10 10 20 10 10/10 30 120 60

Dissolved solids dried at 180 degrees Celsius, 

water, filtered, milligrams per liter

10/10 436 587 543 10/10 240 394 342

Suspended solids, water, unfiltered, milligrams 

per liter

10/10 7 111 20 10/10 200 1,350 739

Alkalinity, water, filtered, fixed endpoint (pH 4.5) 

titration, field, milligrams per liter as calcium 

carbonate

19/19 180 250 220 10/10 100 150 140

Major ions

Calcium, water, filtered, milligrams per liter 19/19 82.0 96.0 87.0 10/10 41.0 61.0 54.5

Magnesium, water, filtered, milligrams per liter 19/19 13.0 20.0 18.0 10/10 7.00 12.0 10.3

Potassium, water, filtered, milligrams per liter 19/19 3.20 9.00 6.70 10/10 4.74 6.50 5.50

Sodium, water, filtered, milligrams per liter 19/19 46.0 84.0 73.0 10/10 28.0 52.0 41.8

Chloride, water, filtered, milligrams per liter 19/19 45.0 110 92.0 10/10 34.0 68.0 52.0

Sulfate, water, filtered, milligrams per liter 19/19 60.0 85.0 74.0 10/10 32.0 55.0 45.0

Nutrients

Ammonia, water, filtered, milligrams per liter as 

nitrogen

17/18 0.030 0.270 0.070 10/10 0.020 0.178 0.090

Nitrate plus nitrite, water, filtered, milligrams per 

liter as nitrogen

17/18 0.87 14.0 9.80 10/10 2.94 5.60 4.40

Organic nitrogen, water, unfiltered, milligrams 

per liter

9/9 0.33 0.57 0.45 10/10 0.22 3.1 1.2

Phosphorus, water, filtered, milligrams per liter as 

phosphorus

18/19 0.50 3.1 1.3 10/10 0.39 0.9 0.6

Total nitrogen, water, unfiltered, milligrams per 

liter

9/9 1.3 15 9.9 10/10 3.4 8.8 5.7
Table 4 53

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Trace elements

Beryllium, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Cadmium, water, unfiltered, micrograms per liter 0/10 -- -- -- 2/10 1.0 2.0 1.5

Chromium, water, unfiltered, recoverable, 

micrograms per liter

7/10 1.0 13.0 1.9 10/10 5.8 21.0 13.3

Copper, water, unfiltered, recoverable, 

micrograms per liter

10/10 2.0 3.0 2.0 10/10 8.0 27.6 15.5

Lead, water, unfiltered, recoverable, micrograms 

per liter

3/10 1.0 3.0 1.0 10/10 16.0 91.0 53.0

Mercury, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.1 0.1 0.1

Nickel, water, unfiltered, recoverable, micrograms 

per liter

10/10 2.0 8.0 3.0 10/10 5.0 18.8 13.2

Silver, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/10 -- -- --

Thallium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/4 -- -- --

Zinc, water, unfiltered, recoverable, micrograms 

per liter

9/10 20 30 20 10/10 50 210 130

Antimony, water, unfiltered, EPA contract, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Arsenic, water, unfiltered, micrograms per liter 3/10 1 2 1 10/10 2 6 5

Cyanide, water, unfiltered, milligrams per liter 0/10 -- -- -- 0/10 -- -- --

Selenium, water, unfiltered, micrograms per liter 0/10 -- -- -- 0/10 -- -- --

Organic compounds

1,2,3-Trichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromo-3-chloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dibromoethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,4-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4,6-Trichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --
54 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

2,4-Dichlorophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2,4-Dimethylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2-Methyl-4,6-dinitrophenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

4-Chloro-3-methylphenol, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

4-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Acrylonitrile, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Aldrin, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/10 -- -- --

alpha-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

alpha-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

beta-Endosulfan, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

beta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Bromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chlordane (technical), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/10 -- -- --

cis-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

cis-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

delta-HCH, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Diazinon, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.20 0.20 0.20 2/4 0.10 0.10 0.10

Dieldrin, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.02 0.02 0.02

Endosulfan sulfate, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Endrin aldehyde, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Endrin, water, unfiltered, recoverable, micrograms 

per liter

0/10 -- -- -- 0/10 -- -- --
Table 4 55

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Heptachlor epoxide, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Heptachlor, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Hexachlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Lindane, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.03 0.03 0.03 0/10 -- -- --

p,p’-DDD, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.1 0.1 0.1

p,p’-DDE, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.08 0.08 0.08

p,p’-DDT, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.2 0.2 0.2

Pentachlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Toxaphene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

trans-1,3-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

trans-Chlordane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1016, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1221, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1232, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1242, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1248, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/10 -- -- --

Aroclor 1254, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.1 0.1 0.1

Aroclor 1260, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/10 0.1 0.1 0.1

1,1,1,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,1-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

1/10 0.4 0.4 0.4 0/4 -- -- --

1,1,2,2-Tetrachloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --
56 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

1,1,2-Trichloro-1,2,2-trifluoroethane, water, 

unfiltered, recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1,2-Trichloroethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,1-Dichloropropene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,3-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2,4-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,2-Diphenylhydrazine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

1,3,5-Trimethylbenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

1,3-Dichlorobenzene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,2-Dichloropropane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2,4-Dinitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2,4-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2,6-Dinitrotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2-Chloroethyl vinyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Chloronaphthalene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2-Chlorophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

2-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

2-Nitrophenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --
Table 4 57

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

3,3’-Dichlorobenzidine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

4-Bromophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

4-Chlorophenyl phenyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

4-Chlorotoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

4-Isopropyltoluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

9H-Fluorene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Acenaphthene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Acenaphthylene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Acrolein, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Anthracene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Benzo[a]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzo[a]pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzo[b]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzo[ghi]perylene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzo[k]fluoranthene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Benzyl n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Bis(2-chloroethoxy)methane, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Bis(2-chloroethyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Bis(2-chloroisopropyl) ether, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Bis(2-ethylhexyl) phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --
58 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Bromobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Bromodichloromethane, water, unfiltered, 

recoverable, micrograms per liter

10/10 1.1 3.1 1.7 4/4 0.6 2.4 1.4

Chlorobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chloromethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Chrysene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

cis-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dibenzo[a,h]anthracene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Dibromochloromethane, water, unfiltered, 

recoverable, micrograms per liter

10/10 0.9 2.7 1.2 4/4 0.5 1.7 1.1

Dibromomethane, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichlorodifluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Dichloromethane, water, unfiltered, recoverable, 

micrograms per liter

1/10 0.2 0.2 0.2 2/4 0.2 0.3 0.3

Diethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Dimethyl phthalate, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Di-n-butyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Di-n-octyl phthalate, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Ethylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Fluoranthene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Hexachlorobutadiene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Hexachlorocyclopentadiene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --
Table 4 59

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Hexachloroethane, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Indeno[1,2,3-cd]pyrene, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Isophorone, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Isopropylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Methyl tert-butyl ether, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 1/4 0.2 0.2 0.2

Naphthalene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

n-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Nitrobenzene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

N-Nitrosodimethylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

N-Nitrosodi-n-propylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

N-Nitrosodiphenylamine, water, unfiltered, 

recoverable, micrograms per liter

0/9 -- -- -- 0/4 -- -- --

n-Propylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Oil and grease, water, unfiltered, freon extraction, 

gravimetric, recoverable, milligrams per liter

1/10 1 1 1 3/7 1 3 2

Organic carbon, water, unfiltered, milligrams per 

liter

10/10 2.9 5.5 3.9 10/10 14.0 47.0 27.0

Phenanthrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Phenol, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

Phenolic compounds, water, unfiltered, 

recoverable, micrograms per liter

3/9 2 3 2 2/10 2 2 2

Pyrene, water, unfiltered, recoverable, 

micrograms per liter

0/9 -- -- -- 0/4 -- -- --

sec-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Styrene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

tert-Butylbenzene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --
60 Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98

Table 4. Summary statistics of detected concentrations of periodic and stormflow samples collected from the study area, Bexar 

County, Texas, 1992–98.—Continued

[n, number; median values represent median of detected values]

U.S. Geological Survey station number 08181800

San Antonio River near Elmendorf, Tex.

(SAR Elmendorf)

Periodic samples Stormflow samples

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

n 

(detects/

samples)

Minimum

value

Maximum 

value

Median 

value

Tetrachloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tetrachloromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Toluene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 1/4 0.3 0.3 0.3

trans-1,2-Dichloroethene, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Tribromomethane, water, unfiltered, recoverable, 

micrograms per liter

7/10 0.2 0.4 0.2 2/4 0.3 0.3 0.3

Trichloroethene, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichlorofluoromethane, water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Trichloromethane, water, unfiltered, recoverable, 

micrograms per liter

10/10 0.8 4.1 2.3 4/4 1.1 3.1 2.1

Trihalomethanes, water, unfiltered, maximum 

summation, micrograms per liter

7/10 3.0 9.0 5.0 2/4 5.7 7.5 6.6

Vinyl chloride, water, unfiltered, recoverable, 

micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Xylene (all isomers), water, unfiltered, 

recoverable, micrograms per liter

0/10 -- -- -- 0/4 -- -- --

Publishing support provided by

Lafayette Publishing Service Center

Information regarding water resources in Texas is available at 

http://tx.usgs.gov/
 
Banta and others—Surface-Water Quality in the Upper San Antonio River Basin, Bexar County, Texas, 1992–98—DS 738

Printed on recycled paper

I SBN 978- 1- 4113-3532- 5

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