WEST

FORK TRINITY

RIVER

ELMFORK TRINITY

R.

TRINITY

RIVER

EAST FORK

 TRINITY

 RIVER

EAGLE

 MOUNTAIN

 LAKE

LAKE

 WORTH

BENBROOK

 LAKE JOE POOL

 LAKE

MOUNTAIN

 CREEK

 LAKE

GRAPEVINE

 LAKE

LAKE

 RAY

 HUBBARD

 LAKE

ARLINGTON

TARRANT

 COUNTY

DENTON

 COUNTY

COLLIN

 COUNTY

DALLAS

 COUNTY

32o52'30"

97o

30'

97o

15' 97o

96o30'

96o

45'

32o

37'30"

0 5 10 15 MILES

Industrial

Residential

Highway

Commercial

Residential

Commercial

Industrial

Highway

Mixed

Undeveloped

REACTIVATED

SITES

DISCONTINUED

SITES

NEW SITES

1

3

4

5

16

17

19

20

31

35

EXPLANATION

PREDOMINANT LAND USE

FORT

 WORTH

ARLINGTON

IRVING DALLAS

PLANO

GARLAND

MESQUITE

8

I–820

I–820

I–35W

State 121

State 

121

I–20

I–35W

I–35E

I–635

Loop 12

I–20 US 75

US 75

Loop 12

I–30

I–35E

I–30

US 183

I-635

1

2

10

14

3

6 7

12

4

9

11

5

13

15

16

18

24

25

27

29

30 19

21 22

23

26

20

17

28

31

32

33

34

36

37

35

Texas Department of Transportation (TxDOT) Districts in the 

Dallas-Fort Worth (DFW) area to meet the regulatory requirements of the application phase for the National Pollutant Discharge Elimination System (NPDES) stormwater permit. The 

Phase I permit requirements applied to cities with populations 

of 100,000 or greater and to TxDOT districts with population centers of 100,000 or greater (U.S. Environmental Protection Agency, 

1990). The following cities and districts in the DFW area met 

the population criteria: Arlington, Dallas, Fort Worth, Garland, 

Beginning in 1997, the approved stormwater disch

were issued to the seven cities and two TxDOT distri

required a permit-compliance phase with additional s

a 5-year period. In 1997, the USGS began a study in 

with the NCTCOG to collect stormwater samples and 

stormwater runoff for the seven cities and two TxDOT 

the period 1997–2001. At the end of the 5-year permit

phase, the EPA will transfer the stormwater discharge 

to the Texas Natural Resource Conservation Commis

U.S. Department of the Interior

U.S. Geological Survey

USGS Fa

Digital base from U.S. Geological Survey

Scale 1:2,000,000

Albers equal-area projection based on

Standard parallels 45.5 and 29.5 degrees

Figure 1. Location of study area and stormwater monitoring sites.

TEX

Study are

LOCATION 

Site numbers 

referenced in ta
2

renewal. The USGS, during an ongoing study, will analyze the 

data collected during the permit-compliance phase and recommend possible changes to the network design and sampling 

schedule. This fact sheet describes the monitoring network and 

sampling schedule during the permit-application phase and the 

5-year permit-compliance phase (1997–2001) and summarizes the 

sampling during February 1997–February 2000.

Description of Study Area

The DFW area is located in north-central Texas (fig. 1), and 

the 1,700-square-mile area lies within Collin, Dallas, Denton, and 

Tarrant Counties. The DFW area is in the upper Trinity River 

Basin with three major tributaries of the Trinity River draining the 

area—West Fork Trinity River, Elm Fork Trinity River, and East 

Fork Trinity River. Mean annual precipitation in the study area 

varies from about 31 inches in Tarrant County to 36 inches in Dallas County, with the months of April and May typically the wettest 

and the months of July and August the driest (Ramos, 1999).

Monitoring Sites

During the permit-application phase, 30 monitoring sites were 

established during 1992–93 in small (160 acres or less) drainage 

basins, each categorized by a single predominant land use (11 residential, 9 industrial, 6 commercial, and 4 highway). Five sites 

each were located in the cities of Dallas and Fort Worth, four in 

Arlington, three each in Garland, Irving, Mesquite, and Plano, and 

two sites each in TxDOT Dallas and TxDOT Fort Worth. Fifteen 

of the original 30 monitoring sites (1–15, table 1) were reactivated 

in 1997 for the permit-compliance phase, including 4 residential, 

4 industrial, 4 commercial, and 3 highway. Three sites each are 

located in Dallas and Fort Worth, two sites each in Arlington and 

TxDOT Dallas, and one site each in Garland, Irving, Mesquite, 

Plano, and TxDOT Fort Worth. The remaining 15 sites were discontinued (16–30, table 1). Seven new sites (31–37, table 1) were 

established during 1997–98 for the permit-compliance phase. One 

site is located in each of the seven cities; no new TxDOT sites 

were established. Six of the new sites are located in drainage 

basins with mixed land use, and one site is located in an undeveloped drainage basin. Three of the six sites with mixed land use are 

located at outfalls with drainage areas less than 500 acres, and the 

remaining three sites are located instream with drainage areas of 

at least 2,500 acres (table 1). Most of the monitoring sites are 

located at storm sewer outfalls or concrete-lined open channels. 

Two sites are located at natural channels.

Each site houses the monitoring equipment in a shelter (photo 

A). A rain gage and solar panel are attached to the shelter. Inside 

the shelter (photo B) are an automatic sampler, a peristaltic pump, 

a datalogger, and a gas bubbler system. The stage of the water in a 

culvert or open channel is measured using a pressure transducer 

and a gas bubbler system that regulates the periodic release of a 

bubble of carbon dioxide through an orifice line below the water 

surface. The pressure transducer measures the pressure required to 

force the bubble out of the orifice line and converts the pressure to 

the stage of the water, in feet. The stage then is used to compute 

the instantaneous discharge using a different equation specific 

for a flume, open channel, or weir. The datalogger computes discharge, accumulates the volume of runoff, and stores information, 

such as date, time, precipitation, stage, discharge, volume, and 

number of samples collected. The equipment is powered by a 

12-volt battery maintained by the solar panel. A telephone line 

and a modem are installed at each site to provide telemetry to 

communicate with each site remotely to monitor a storm event, 

download data, modify program parameters, enable or disable the 

automatic sampler, and notify personnel of a storm event. 

Sample Collection and Analysis

Two conditions are required for sample collection: (1) Antecedent dry weather conditions (no more than 0.1 inch of precipitation in a 24-hour period) should occur for the 72 hours prior to the 

storm event to allow for accumulation of possible contaminants. 

rain gage

solar panel

shelter

A. Equipment shelter and solar panel for undeveloped site in 

Plano, Tex.; the rain gage is mounted just above the solar panel.

B. Inside an equipment shelter.

grab sample bottles datalogger

automatic 

peristaltic pump

gas bubbler system

pressure transducer

sampler
3

(2) The total storm precipitation should range between 0.2 and 

1.5 inches (Baldys and others, 1998).

During the permit-application phase, seven samples were collected at each of the 30 sites and analyzed for 188 selected properties and constituents (Baldys and others, 1997). During the 5-year 

permit-compliance phase, the 13 samples scheduled for the 15 

reactivated sites and the 24 samples scheduled for the 7 new sites 

will be analyzed for a reduced list of 23 required properties and 

constituents. The permit-compliance sampling schedule is divided 

into 6-month periods (September–February and March–August), 

during which a predetermined number of samples are to be collected. For the reactivated sites, five samples were scheduled in 

the first year (two samples in the first 6-month period and three 

samples in the next period) and two samples per year (one in each 

6-month period) for the following 4 years. For the new sites, six 

samples per year (three in each 6-month period) are scheduled for 

the last 4 years of the 5-year period. Table 1 lists the number of 

samples scheduled for the permit-compliance period and the number of samples actually collected during February 1997–February 

2000. Some samples were not collected as scheduled because of 

extended periods of little or no precipitation.

Two types of samples are collected for analysis of waterquality properties and constituents. Grab samples are collected 

manually, and composite samples are collected by the automatic 

sampler. The samples are analyzed for selected properties and 

constituents in accordance with guidelines set by EPA (U.S. Environmental Protection Agency, 1992). Figure 2 shows an example 

of the accumulated precipitation, the discharge, and the times of 

the grab and composite aliquot samples for a storm sampled on 

May 15, 1997, at site 08056390 Bastille Street Outfall at La 

Reunion Parkway, Dallas, Texas.

Table 1. NPDES municipal stormwater sites in the Dallas-Fort Worth area and summary of sampling, February 1997–February 2000 

[Sites 1–15 established 1992–93 during permit-application phase; sites 16–30 established 1992–93 during permit-application phase and discontinued 1997–98 during permit-compliance phase; 

sites 31–37 established 1997–98 during permit-compliance phase. USGS, U.S. Geological Survey; TxDOT, Texas Department of Transportation] 

Site

no.

(fig. 1)

USGS

station

no.

Station name City or 

TxDOT district

Predominant land

use

Drainage

area 

(acres)

No. of samples

Collected

1992–94

Scheduled

1997–2001

Collected

Feb. 1997–

Feb. 2000

Reactivated sites

1 08048505 Pylon Street Outfall at Meacham Rd. Fort Worth Industrial 151 7 13 10

2 08048545 Dry Branch Outfall at 33d St. Fort Worth Industrial 73.7 7 13 10

3 08048700 Eastern Hills High School Outfall at Weiler Dr. Fort Worth Residential 151 7 13 9

4 08048920 Deer Creek Outfall at I–35W TxDOT Fort Worth Highway 63.1 7 13 10

5 08049220 The Parks Mall Outfall at I–20W Arlington Commercial 38.8 7 13 10

6 08049320 River Legacy Park Outfall at Green Oaks Blvd. Arlington Residential 160 7 13 9

7 08049590 Bear Creek Outfall at Shady Grove Rd. Irving Residential 65.3 7 13 10

8 08049860 Mountain Creek Outfall at I–20 TxDOT Dallas Highway 115 7 13 9

9 08055690 Bachman Branch Outfall at I–635 TxDOT Dallas Highway 12 7 13 3

10 08056390 Bastille Street Outfall at La Reunion Pkwy. Dallas Industrial 49.5 7 13 10

11 08057135 White Rock Creek Outfall at Preston Rd. Dallas Commercial 59.1 7 13 9

12 08057441 Newton Creek Outfall at Tioga St. Dallas Residential 38.9 7 13 9

13 08061525 Spring Creek Outfall at Park Blvd. Plano Commercial 22.7 7 13 10

14 08061635 Tributary to Duck Creek Outfall at Hightower Rd. Garland Industrial 33.9 7 13 10

15 08061910 South Mesquite Creek Outfall at I–635 Mesquite Commercial 45.9 7 13 8

Discontinued sites

16 08047100 Clear Fork Trinity River Outfall at Oak Hill Cr. Fort Worth Residential 61.7 7 -- --

17 08048510 West Fork Trinity River Outfall at Highway 121 Fort Worth Commercial 136 7 -- --

18 08049360 Tributary to West Fork Trinity River Outfall at Baird’s Farm Rd. Arlington Residential 77.0 7 -- --

19 08049470 Tributary to Johnson Creek Outfall at I–30 East Arlington Industrial 85.5 7 -- --

20 08049950 Fish Creek Outfall at I–20 TxDOT Fort Worth Highway 40.9 7 -- --

21 08055570 Hereford Rd. Outfall at Walnut Hill Ln. Irving Industrial 43.4 7 -- --

22 08055590 Joe’s Creek Outfall at Denton Dr. Dallas Industrial 9.0 7 -- --

23 08056100 Tributary to Elm Fork Trinity River Outfall at Cascade St. Irving Industrial 43.9 7 -- --

24 08057310 Ash Creek Outfall at Whittier St. Dallas Residential 71.3 7 -- --

25 08061510 Rowlett Creek Outfall at Willow Creek Park Plano Residential 51.4 7 -- --

26 08061530 Spring Creek Outfall at Avenue F Plano Industrial 49.0 7 -- --

27 08061660 Sleepy Hollow St. Outfall at Northwest Highway Garland Residential 67.3 7 -- --

28 08061690 I–635 Outfall at Centerville Rd. Garland Commercial 36.2 7 -- --

29 08061915 South Mesquite Creek Outfall at South Parkway Mesquite Residential 45.4 7 -- --

30 08061940 South Mesquite Creek Outfall at Bruton Rd. Mesquite Residential 46.2 7 -- --

New sites

31 08048542 Sycamore Creek at Scott Ave. Fort Worth Mixed 21,760 -- 24 12

32 08049240 Rush Creek at Woodland Park Blvd. Arlington Mixed 17,024 -- 24 10

33 08055550 Cottonwood Branch Tributary Outfall at Sky Cir. Irving Mixed 127.7 -- 24 6

34 08056450 Knights Branch Tributary at Cedar Springs Rd. Dallas Mixed 486.4 -- 24 12

35 08061515 Beck Branch Outfall at Wyngate Blvd. Plano Undeveloped 70.4 -- 24 9

36 08061545 Mills Branch Tributary at N. Fifth St. Garland Mixed 268.8 -- 24 13

37 08061850 North Mesquite Creek at Beltline Rd. Mesquite Mixed 2,500 -- 24 9
4

The grab sample typically is collected during the first 2 hours 

of a storm to catch the first flush of the basin—the initial stormwater runoff that often contains accumulations of possible 

contaminants. The grab sample is analyzed for fecal coliform 

bacteria, fecal streptococcus bacteria, oil and grease, phenols 

(TxDOT Dallas only), and field properties. The field properties—

specific conductance, pH, and water temperature—are measured 

at the time of sample collection.

The composite sample is a combination of discharge-weighted 

sample aliquots collected throughout a storm by the automatic 

sampler programmed to collect discrete samples after a sitespecific pre-specified volume of discharge has passed the site. 

The composite sample is analyzed for biochemical oxygen 

demand, chemical oxygen demand, suspended solids, dissolved 

solids, ammonia plus organic nitrogen, nitrite plus nitrate nitrogen, total phosphorous, dissolved phosphorous, arsenic, cadmium, 

chromium, copper, lead, nickel (TxDOT Dallas only), zinc, and 

diazinon.

Data Analysis and Use

The concentration data compiled by the monitoring program are used primarily for permit compliance to characterize 

the stormwater runoff in the DFW area. The event-mean 

concentration data can be used to (1) characterize stormwater runoff, both for individual land uses and for the entire DFW area; 

(2) estimate storm loads and mean annual loads for selected constituents to receiving waters; and (3) provide policy makers with 

information to develop effective management practices. These 

data also are useful for comparison and analysis in other parts of 

the state and country.

References

Baldys, Stanley, III, Raines, T.H., Mansfield, B.L., and Sandlin, 

J.T., 1997, Hydrologic data for the urban stormwater studies 

in the Dallas-Fort Worth area, Texas, 1992–94: U.S. Geological Survey Open-File Report 96–482, 256 p.

______1998, Urban stormwater quality, event-mean concentrations, and estimates of stormwater pollutant loads, DallasFort Worth area, Texas, 1992–93: U.S. Geological Survey 

Water-Resources Investigations Report 98–4158, 51 p.

Ramos, M.G., ed., 1999, 2000–2001 Texas almanac: The Dallas 

Morning News, 672 p.

U.S. Environmental Protection Agency, 1990, National Pollutant 

Discharge Elimination System permit application regulations 

for stormwater discharges—Final rule: U.S. Federal Register, 

v. 55, no. 222, p. 47,989–48,091.

_____1992, National Pollutant Discharge Elimination System 

stormwater sampling guidance document: U.S. Environmental Protection Agency, 121 p.

—Stephanie J. Moore, Timothy H. Raines, and Stanley Baldys III

Any use of trade, product, or firm names is for descriptive 

purposes only and does not imply endorsement by the 

U.S. Government.

Information on technical reports and hydrologic data related 

to this study can be obtained from:

Fort Worth Subdistrict Chief Phone: (817) 263–9545

U.S. Geological Survey FAX: (817) 361–0459

Fort Worth Field Headquarters World Wide Web: 

2775 Alta Mesa Blvd. http://tx.usgs.gov/

Fort Worth, TX 76133

Figure 2. Hydrograph showing accumulated precipitation, discharge, and times of composite- and grab-sample collection at 08056390 

Bastille Street Outfall at La Reunion Parkway, Dallas, Texas, May 15, 1997.

1015 1030 1045 1100 1115 1130 1145 1200 1215 1230 1245 1300 1315 1330

15

May 1997

0

0.9

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

ACCUMULATED PRECIPITATION, IN INCHES

0

100

10

20

30

40

50

60

70

80

90

DISCHARGE, IN CUBIC FEET PER SECOND

Accumulated precipitation

Discharge

Composite sample 

Grab sample