U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2011–5224

Prepared in cooperation with the Texas Water Development Board

Base Flow (1966–2009) and Streamflow Gain and Loss (2010) 

of the Brazos River from the New Mexico–Texas State Line 

to Waco, Texas
Front cover: Looking downstream from Highway 16 and U.S. Geological Survey streamflow-gaging station 08088610 Brazos River near Graford, Texas

Back cover: Looking downstream from U.S. Geological Survey streamflow-gaging station 08091500 Paluxy River at Glen Rose, Texas, April 27, 2010
Base Flow (1966–2009) and Streamflow 

Gain and Loss (2010) of the Brazos River 

from the New Mexico–Texas State Line 

to Waco, Texas

By Stanley Baldys III and Frank E. Schalla

Prepared in cooperation with the Texas Water Development Board

Scientific Investigations Report 2011–5224

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

Suggested citation:

Baldys, Stanley, III, and Schalla, F.E., 2012, Base flow (1966–2009) and streamflow gain and loss (2010) of the 

Brazos River from the New Mexico–Texas State line to Waco, Texas: U.S. Geological Survey Scientific 

Investigations Report 2011-5224, 53 p.

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

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To learn about the USGS and its information products visit http://www.usgs.gov/

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Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

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.
iii

Acknowledgments 

The authors thank the following individuals for their assistance with data-collection 

activities throughout the study: Clint Walker, John R. Howell, Dana A. Blanchette, Gary F. Burke, 

Brandon A. Cooper, Travis T. Dowell, Nathan J. McSloy, Samuel W. Kelley, Jeffrey T. Sandlin, 

Michael D. Scheider, Phillip C. Teeters, Jason L. Taylor, and Steven T. Loesch.
iv
v

Contents

Acknowledgments .......................................................................................................................................iii

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

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

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

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

Methods.........................................................................................................................................................12

Hydrograph Separation and Trend Analysis ..................................................................................12

Data Collection....................................................................................................................................15

Streamflow Gain and Loss Computation.........................................................................................20

Quality Assurance...............................................................................................................................20

Base Flow......................................................................................................................................................20

Salt Fork and Double Mountain Fork Brazos River Basin ............................................................21

Clear Fork Brazos River Basin ..........................................................................................................21

North Bosque River Basin.................................................................................................................21

Brazos River Basin (main stem) .......................................................................................................27

Streamflow Gain and Loss Assessment ..................................................................................................33

Salt Fork Brazos River Basin.............................................................................................................33

Double Mountain Fork Brazos River Basin.....................................................................................34

Clear Fork Brazos River Basin ..........................................................................................................35

North Bosque River Basin ...............................................................................................................36

Brazos River Basin (main stem) .......................................................................................................38

Contributions of Streamflow to the Main Channels of Each of the Five Subbasins ...............41

Summary .......................................................................................................................................................41

References....................................................................................................................................................44

Appendix 1. Hydrographic Separation Results ...................................................................................46

Figures

1. Map showing upper Brazos River Basin, Texas......................................................................3

2. Map showing major-aquifer boundaries and sites where streamflow and 

specific conductance were measured, June and October 2010, upper 

Brazos River Basin, Texas...........................................................................................................4

3. Map showing minor-aquifer boundaries and sites where streamflow and 

specific conductance were measured, June and October 2010, upper 

Brazos River Basin, Texas...........................................................................................................5

4. Map showing sites where streamflow and specific conductance were 

measured in June and October 2010, Salt Fork Brazos River Basin, Texas........................7

5. Map showing sites where streamflow and specific conductance were 

measured in June and October 2010, Double Mountain Fork Brazos River 

Basin, Texas...................................................................................................................................8
vi

6. Map showing sites where streamflow and specific conductance were 

measured in June and October 2010, Clear Fork Brazos River Basin, Texas .....................9

7. Map showing sites where streamflow and specific conductance were 

measured in June and October 2010, North Bosque River Basin, Texas..........................10

8. Map showing sites where streamflow and specific conductance were 

measured in June and October 2010, main stem of the Brazos River and 

tributaries to the main stem, Texas .........................................................................................11

9. Graph showing hydrograph separation of streamflow for U.S. Geological 

Survey streamflow-gaging station 08089000 Brazos River near Palo Pinto, 

Texas, 1978 water year...............................................................................................................14

10. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08082000 Salt Fork Brazos River near 

Aspermont, Texas, 1966–2009...................................................................................................22

11. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08080500 Double Mountain Fork Brazos River 

near Aspermont, Texas, 1966–2009..........................................................................................22

12. Graphs showing A, Time series of annual base-flow index and B, Relation 

between annual base-flow index for U.S. Geological Survey streamflowgaging stations 08080500 Double Mountain Fork Brazos River near 

Aspermont, Texas, and 08082000 Salt Fork Brazos River near Aspermont, 

Tex., 1966–2009............................................................................................................................23

13. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08084000 Clear Fork Brazos River at Nugent, 

Texas, 1966–2009.........................................................................................................................24

14. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08085500 Clear Fork Brazos River at Fort Griffin, 

Texas, 1966–2009.........................................................................................................................24

15. Graphs showing A, Time series of annual base-flow index and B, Relation 

between annual base-flow index for U.S. Geological Survey streamflowgaging station 08084000 Clear Fork Brazos River near Nugent, Texas, and 

U.S. Geological Survey streamflow-gaging station 08085500 Clear Fork 

Brazos River at Fort Griffin, Tex., 1966–2009...........................................................................25

16. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08095000 North Bosque River near Clifton, 

Texas, 1966–2009.........................................................................................................................26

17. Graph showing annual base-flow index at U.S. Geological Survey 

streamflow-gaging station 08082500 Brazos River at Seymour, 

Texas, 1967–2009.........................................................................................................................28

18. Graph showing annual base-flow index at U.S. Geological Survey 

streamflow-gaging station 08088000 Brazos River near South Bend, 

Texas, 1966–2009.........................................................................................................................28
vii

19. Graphs showing A, Time series of annual base-flow index and B, Relation 

between annual base-flow index for U.S. Geological Survey streamflowgaging station 08082500 Brazos River at Seymour, Texas, and U.S. Geological 

Survey streamflow-gaging station 0808800 Brazos River near South Bend, 

Tex., 1967–2009............................................................................................................................29

20. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08089000 Brazos River near Palo Pinto, 

Texas, 1966–2009.........................................................................................................................30

21. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08090800 Brazos River near Dennis, 

Texas, 1969–2009.........................................................................................................................30

22. Graphs showing A, Time series of annual base-flow index and B, Relation 

between annual base-flow index for U.S. Geological Survey streamflowgaging station 08089000 Brazos River near Palo Pinto, Texas, 1966–2009, 

and U.S. Geological Survey streamflow-gaging station 08090800 Brazos 

River near Dennis, Tex., 1969–2009..........................................................................................31

23. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08091000 Brazos River near Glen Rose, 

Texas, 1966–2009.........................................................................................................................32

24. Graph showing annual base-flow index for U.S. Geological Survey 

streamflow-gaging station 08091500 Paluxy River at Glen Rose, 

Texas, 1966–2009.........................................................................................................................32

25. Graph showing instantaneous streamflow measured during June 2010 at 

U.S. Geological Survey streamflow-gaging stations in the five subbasins of 

the upper Brazos River Basin, Texas (Salt Fork Brazos River, Double 

Mountain Fork Brazos River, Clear Fork Brazos River, North Bosque River, 

and the main stem of Brazos River and its tributaries) ........................................................42

26. Graph showing instantaneous streamflow measured during October 2010 at 

U.S. Geological Survey streamflow-gaging stations in the five subbasins of 

the upper Brazos River Basin, Texas (Salt Fork Brazos River, Double 

Mountain Fork Brazos River, Clear Fork Brazos River, North Bosque River, and 

the main stem of Brazos River and its tributaries)................................................................42

Tables

1. U.S. Geological Survey streamflow-gaging stations in the upper Brazos 

River Basin that provided data for hydrographic separation, water years 

1966–2009 (October 1965 through September 2009) .............................................................13

2. Streamflow and specific-conductance values measured during June and 

October 2010 in the upper Brazos River Basin, Texas..........................................................16
viii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.4047 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3)

acre-foot (acre-ft) 0.001233 cubic hectometer (hm3) 

Flow rate

foot per day (ft/d) 0.3048 meter per day (m/d)

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

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).

A water year is the 12-month period October 1 through September 30 designated by the 

calendar year in which it ends.
Base Flow (1966–2009) and Streamflow Gain and 

Loss (2010) of the Brazos River from the New Mexico–

Texas State Line to Waco, Texas

By Stanley Baldys III and Frank E. Schalla

Abstract 

During 2010–11, the U.S. Geological Survey (USGS), 

in cooperation with the Texas Water Development Board, 

used hydrograph separation to quantify historical base flow 

at 11 USGS streamflow-gaging stations between water 

years 1966–2009 and streamflow gains and losses from two 

sets of synoptic measurements of streamflow and specific 

conductance (the first in June 2010, followed by another set 

in October 2010) in the upper Brazos River Basin from the 

New Mexico–Texas State line to Waco, Texas. The following 

subbasins compose the study area: Salt Fork Brazos River 

Basin, Double Mountain Fork Brazos River Basin, Clear 

Fork Brazos River Basin, North Bosque River Basin, and the 

Brazos River Basin (main stem) (including its tributaries). 

Base-flow analysis was done using historical streamflow 

data from 11 USGS streamflow-gaging stations in the upper 

Brazos River Basin to compute yearly base-flow indexes 

(base flow divided by total streamflow) for each station. The 

base-flow index was used to indicate the fraction of flow 

consisting of base flow on an annual basis for the period of 

record evaluated at each streamflow-gaging station. At nine 

stations there were long-term streamflow data from water 

years 1966–2009 (October 1965 through September 2009); 

at two stations slightly shorter periods of record (water years 

1967–2009 and 1969–2009) were available. The median baseflow indexes were 0.16 and 0.15 at USGS streamflow-gaging 

stations 08082000 Salt Fork Brazos River near Aspermont, 

Tex., and 08080500 Double Mountain Fork Brazos River 

near Aspermont, Tex., respectively. The amount of the total 

streamflow consisting of base flow was larger at sites in the 

Clear Fork Brazos River Basin compared to sites in the Salt 

Fork Brazos River Basin or Double Mountain Fork Brazos 

River Basin; at USGS streamflow-gaging stations 08084000 

Clear Fork Brazos River at Nugent, Tex., and at 08085500 

Clear Fork Brazos River at Fort Griffin, Tex., the median 

base-flow indexes were 0.28 and 0.23, respectively. The 

largest median base-flow index for any station was 0.35 at 

USGS streamflow-gaging station 08091500 Paluxy River 

at Glen Rose, Tex. The second largest base-flow index was 

0.30 at USGS streamflow-gaging station 08095000 North 

Bosque River near Clifton, Tex. Median base-flow indexes 

on the main stem of the Brazos River upstream from Possum 

Kingdom Lake were 0.22 at USGS streamflow-gaging 

station 08082500 Brazos River at Seymour, Tex., and 0.24 

at USGS streamflow-gaging station 08088000 Brazos River 

near South Bend, Tex. The base-flow indexes for stations 

between Possum Kingdom Lake and Lake Granbury were 

0.19 and 0.27 at USGS streamflow-gaging stations 08089000 

Brazos River near Palo Pinto, Tex., and 08090800 Brazos 

River near Dennis, Tex., respectively. A median base-flow 

index of 0.19 was also measured at USGS streamflow-gaging 

station 08091000 Brazos River near Glen Rose, Tex., located 

between Lake Granbury and Lake Whitney. A Mann-Kendall 

trend analysis test was performed on annual base-flow index 

values from each of the 11 streamflow records that were 

analyzed. Upward trends in base-flow index values indicating 

increasing flows during the study period were found for USGS 

streamflow-gaging stations 08080500 Double Mountain 

Fork Brazos River near Aspermont, Tex., 08089000 Brazos 

River near Palo Pinto, Tex., and 08090800 Brazos River near 

Dennis, Tex. Flows at these three streamflow-gaging stations 

are regulated by reservoir releases, and additional analyses are 

needed before these streamflow trends can be characterized as 

indicative of changes in base flow over time. 

Streamflow was measured at 66 sites from June 6–9, 

2010, and at 68 sites from October 16–19, 2010, to identify 

reaches in the upper Brazos River Basin that were gaining or 

losing streamflow. Gaining reaches were identified in each 

of the five subbasins. The gaining reach in the Salt Fork 

Brazos River Basin began at USGS streamflow-gaging station 

08080940 Salt Fork Brazos River at State Highway 208 near 

Clairemont, Tex. (site SF–6), upstream from where Duck 

Creek flows into the Salt Fork Brazos River and continued 

downstream past USGS streamflow-gaging station 08082000 

Salt Fork Brazos River near Aspermont, Tex. (site SF–9), to 

the outlet of the basin. In the Double Mountain Fork Brazos 

River Basin, a gaining reach from near Post, Tex., downstream 

to the outlet of the basin was identified. Two gaining reaches 

were identified in the Clear Fork Brazos River Basin—one 
2 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

from near Roby, Tex., downstream to near Noodle, Tex., 

and second from Hawley, Tex., downstream to Nugent, Tex. 

Most of the North Bosque River was characterized as gaining 

streamflow. Streamflow gains were identified in the main stem 

of the Brazos River from where the Brazos River main stem 

forms at the confluence of the Salt Fork Brazos River and 

Double Mountain Fork Brazos River near Knox City, Tex., 

downstream to near Seymour, Tex. 

Introduction

The Brazos River is the longest river in Texas and the 

11th longest river in the United States. The Brazos River 

system extends about 1,280 miles (mi) from its source at the 

head of Blackwater Draw in eastern New Mexico to its mouth 

at the Gulf of Mexico near Freeport, Tex. (Kammerer, 1990) 

(fig. 1). Blackwater Draw crosses the New Mexico–Texas 

border about 186 mi west of the confluence of Salt Fork 

Brazos River and Double Mountain Fork Brazos River, where 

the Brazos River main stem begins west of Lubbock, Tex., 

at river mile 923.2 from the mouth on the Gulf of Mexico 

(U.S. Geological Survey, 2001). The Brazos River continues 

in an easterly direction towards the Dallas–Fort Worth, Tex., 

metropolitan area. The Brazos River then turns south for about 

90 mi towards Waco in McLennan County, Tex., where it is 

joined by outflows of the North Bosque River from Waco Lake 

4.6 mi from the North Bosque mouth on the Brazos River 

upstream from Waco at river mile 404.9 (fig. 1). The Brazos 

River is an important resource to agricultural, municipal, 

and industrial users of water in the Brazos River Basin in 

Texas. Ashworth and Hopkins (1995) classified the major and 

minor aquifers of Texas, and described the major and minor 

aquifers in the upper Brazos River Basin that are hydraulically 

connected to the Brazos River. The major aquifers are the 

Seymour, Ogallala, Edwards-Trinity (Plateau), and Trinity. 

Minor aquifers are the Brazos River Alluvium, Woodbine, 

Edwards-Trinity (High Plains), Dockum, and Blaine 

(figs. 2 and 3). Some of the State’s largest declines in 

groundwater altitudes (350 to more than 1,000 feet [ft]), 

have occurred in an area extending from approximately 

Waco, Tex., to the northern Dallas-Fort Worth, Tex., 

metropolitan area (Texas Water Development Board, 2007b).

Surface-water and groundwater interactions in the upper 

Brazos River Basin upstream from Waco, Tex., to near the 

New Mexico–Texas State line are poorly understood, and base 

flows in the upper basin have not been adequately quantified. 

Slade and others (2002, p. 3) noted “relatively few studies 

have been done involving reaches that intersect the outcrops 

of ...the Ogallala aquifer and none involving the Seymour 

aquifer,” both of which underlie parts of the upper Brazos 

River Basin. A better quantification of base flow in the upper 

Brazos River Basin and the exchange of water between the 

upper Brazos River and the underlying aquifers could assist 

water managers and planners responsible for the long-term 

sustainability of surface-water and groundwater resources in 

this part of the basin.

The Texas Water Development Board (TWDB) is a 

State agency whose goal is to “provide leadership, 

planning, financial assistance, information, and education for 

the conservation and responsible development of water for 

Texas” (Texas Water Development Board, 2010, p. 1). 

The population of Texas exceeded 25 million in 2010, a 

20.6 percent increase from 2000 and the fastest growth 

rate in the United States (U.S. Census Bureau, 2011). In an 

October 2011 newsletter published by Texas A&M University, 

Texas State Climatologist John Nielsen-Gammon notes 

Texas has experienced droughts lasting several years, and 

currently (2011) about 95 percent of Texas is in either a 

severe or exceptional drought status; the past year has been 

the worst one-year drought in the state’s history (Texas A&M 

University, 2011). The population of Texas continues to grow 

rapidly, and with the continual threat of severe drought, the 

need for the TWDB to accomplish its goals in an effective 

and efficient manner intensifies (Texas Water Development 

Board, 2010). To provide information regarding flow 

characteristics of the upper Brazos River Basin to water 

managers, the USGS, in cooperation with the TWDB, 

quantified base flows in the upper Brazos River Basin using 

the results of base-flow analysis (hydrograph separation) 

from the New Mexico–Texas State line downstream to near 

Waco, Tex., and synoptic measurements of streamflow and 

specific conductance. Synoptic measurements are described 

by Beck and Wilson (2006, p. 1) as “those done concurrently 

over a broad area at a set time to give a “snap shot” of 

hydrologic conditions.” This study complements previous 

work that quantified base flows in part of the lower Brazos 

River Basin from near Waco downstream to near Freeport, 

Tex., using base-flow analysis and synoptic streamflow 

measurements (Turco and others, 2007).

Purpose and Scope

This report describes the results of base-flow analysis of 

historical streamflow data at 11 long-term USGS streamflowgaging stations for water years 1966–2009 (October 1965 

through September 2009) and two synoptic streamflow gain 

loss surveys during June and October 2010 in the upper 

Brazos River Basin from the New Mexico–Texas State line 

downstream to near Waco, Tex. For each of the 11 long-term 

USGS streamflow-gaging stations, base-flow indexes were 

determined and statistically tested to assess if they changed 

over time. Streamflow gains and losses based on streamflow 

data collected from 66 measurement sites (June 2010) and 68 

measurement sites (October 2010) on the Brazos River and 

selected tributaries are presented, and the respective gaining 

and losing reaches are identified. Contributions of streamflow 

to the main channels of each of the five subbasins composing 

the upper Brazos River Basin are described.
Introduction 3 Figure 1. Upper Brazos River Basin, Texas.

Blackwater

Draw

Draw

Yellow House

DoubleMountainFork

Brazos River

Salt

Fork

Brazos

River

Brazos

River

Brazos

River

Clear

Fork

Brazos

River

Clear

Fork

Brazos

River

North

BosqueRiver

North Fork Double Mountain Fork Brazos River

South Fork Double Mountain Fork Brazos River

Running Water

Draw

White

River

Lake

Palo

Pinto

Lake

Stamford 

Hubbard Creek

Reservoir

Aquilla Reservoir

Tradinghouse Creek Reservoir

Lake

Whitney

Lake

Granbury

Possum

Kingdom Lake

Lake

Graham

Waco

Lake

Lake Fort

Panthom Hill

White River

Reservoir

SWISHER

COUNTY BRISCOE COUNTY

CASTRO

COUNTY

PARMER COUNTY

MOTLEY

COUNTY

COTTLE

COUNTY

FLOYD 

COUNTY

E COUNTY LAH

B MAL

COUNTY

Y COUNTY ELI AB

FOARD

COUNTY

CLAY

COUNTY

KING

COUNTY KNOX COUNTY

ARCHER COUNTY

DICKENS

COUNTY CROSBY

COUNTY

ROLYAB

COUNTY

LUBBOCK 

COUNTY

COCHRAN 

COUNTY

HOCKLEY

COUNTY

E COUNTY SI W

KENT

COUNTY

AZRAG

COUNTYTHROCKMORTON COUNTY

YOUNG

COUNTY

HASKELL 

COUNTY

LYNN COUNTY YOAKUM COUNTY TERRY COUNTY

PALO

PINTO

COUNTY

PARKER

COUNTY

T NARRAT

COUNTY

SCURRY

COUNTY

FISHER

COUNTY

BORDEN

COUNTY

DAWSON

COUNTY JONES

COUNTY SHACKELFORD

COUNTY

STEPHENS 

COUNTY HOOD

COUNTY JOHNSON COUNTY

ELLIS

COUNTY

MITCHELL

COUNTY

NOLAN COUNTY TAYLOR COUNTY

DNALTS AE

COUNTY

ERATH

COUNTY

CALLAHAN

COUNTY

NAVARRO

COUNTY

SOMERVELL 

COUNTY

H LI L

COUNTY

BOSQUE COUNTY

COKE

COUNTY

COLEMAN

COUNTY RUNNELS COUNTY

BROWN

COUNTY

HAMILTON 

COUNTY

MCLENNAN

COUNTY

LIMESTONE

COUNTY

CORYELL

COUNTY

FALLS COUNTY

BELL 

COUNTY

COMANCHE

COUNTY

STONEWALL 

COUNTY

JACK

COUNTY

TEXAS

NEW MEXICO

Lake Alan

Henry

100°30'

97°30'

99°00'

102°00'

103°30'

34°30'

33°45'

33°00'

32°15'

31°30'

TEXAS

Study area

NEW

MEXICO

Brazos 

River

Basin

Gulf of

Mexico

Freeport

Dallas

Fort

Worth

LOCATION MAP

Waco

Base from U.S. Geological Survey digital data,Water amd boundary features from The NationalAtlas of the United States digital data 1:2,000,000,Hydrologic Unit Code digital data 1:250,000,Texas Centric Mapping System–Albers EqualArea Projection, North American Datum of 1983

EXPLANATION

River basinSalt Fork Brazos RiverBrazos RiverDouble Mountain Fork Brazos RiverClear Fork Brazos RiverNorth Bosque RiverRiver basin boundaryEphemeral streamPerennial streamMain stem

0 50 100 MILES 25 750 50 100 KILOMETERS 25 75
4 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Figure 2. Major-aquifer boundaries and sites where streamflow and specific conductance were measured, June and October 2010, upper Brazos River Basin, Texas.

DENTON

DALLAS

FORT WORTH

MIDLAND Base from U.S. Geological Survey digital data,

Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Major aquifer boundaries fromAshworth and Hopkins, 1995, Texas Centric Mapping System–Albers Equal Area Projection, Unit in Meters, North American Datum of 1983

Salt Fork Brazos River Basin

Double Mountain ForkBrazos River Basin

Brazos River Basin

Clear Fork BrazosRiver Basin

North Bosque

River Basin

CF-9

BMS-2

DMF-8

NB-1

SF-9

0 70 140 MILES0 70 140 KILOMETERS

'

'

'

102° 00

100° 00 '

34° 00

32° 00

98° 00 '

EXPLAN

ATION

River basin boundaryEphemeral streamPerennial streamMeasurement site and site identifier–See table 2River basin Brazos River main stem Brazos River main stem tributary Clear Fork Brazos River Double Mountain Fork Brazos River North Bosque River Salt Fork Brazos River

Major aquifer 

Seymour aquifer Ogallala aquifer Edwards-Trinity (Plateau) aquiferTrinity aquifer outcropTrinity aquifer downdip SF-1

SF-2

SF-3

SF-4

SF-5

SF-6

SF-7 SF-8

SF-9

DMF-1

DMF-2

DMF-3

DMF-4

DMF-5

DMF-6 DMF-7

DMF-8

CF-1

CF-2

CF-3

CF-5

CF-6 CF-8

CF-10

CF-11

CF-12

CF-13

CF-14

CF-15

CF-18

NB-1

NB-2

NB-8

BMS-1

BMS-2

BMS-3

BMS-5 BMS-6

BMST-1

BMST-2 BMST-3

BMST-4

BMST-5

BMST-7

BMST-8

BMST-9

BMST-10

BMST-13

BMST-14

CF-4 CF-7 CF-16

CF-17

CF-19

NB-3 NB-4

NB-5

NB-6

NB-7

NB-9 NB-10

BMS-4

BMS-7

BMS-8

BMST-6

BMST-1

B

1

MST-12

TEXAS

NEW MEXICO

CF-9

BMST-7
Introduction 

5

TEXAS

NEW MEXICO

Salt Fork Brazos River Basin

Double Mountain ForkBrazos River Basin

Brazos River Basin

Clear Fork Brazos River Basin

North Bosque

River Basin

SF-1

SF-2

SF-3

SF-4

SF-5

SF-6

SF-7 SF-8

SF-9

DMF-1

DMF-2

DMF-3

DMF-4

DMF-5

DMF-6 DMF-7

DMF-8

CF-1

CF-2

CF-3

CF-5

CF-6

CF-8

CF-10

CF-11

CF-12

CF-13

CF-14

CF-15

CF-18

NB-1

NB-2

NB-8

BMS-1

BMS-2

BMS-3

BMS-5 BMS-6

BMST-1

BMST-2 BMST-3

BMST-4

BMST-5

BMST-7

BMST-8

BMST-9

BMST-10

BMST-13

BMST-14

CF-4 CF-7 CF-16

CF-17

CF-19

NB-3 NB-4NB-5

NB-6

NB-7

NB-9

NB-10

BMS-4

BMS-7

BMS-8

BMST-6

BMST-1

B

1

MST-12

CF-9

0 70 140 MILES0 70 140 KILOMETERS

102°00'

100°00'

34°00'

32°00'

98°00'

EXPLANATION

Minor aquifer

Brazos River Alluvium Woodbine aquifer outcropWoodbine aquifer downdipEdwards-Trinity (High Plains) aquifer Dockum aquifer outcropDockum aquifer downdipBlaine aquifer outcropBlaine aquifer downdip

CF-9

BMS-2

BMST-5

DMF-8

NB-1

SF-9

River basin boundaryEphemeral streamPerennial streamMeasurement site and site identifier–See table 2River basin Brazos River main stem Brazos River main stem tributary Clear Fork Brazos River Double Mountain Fork Brazos River North Bosque River Salt Fork Brazos River

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Minor Aquifer boundaries fromAshworth and Hopkins 1995, Texas Centric Mapping System–Albers Equal Area Projection,Unit in Meters, North American Datum of 1983

Figure 3. Minor-aquifer boundaries and sites where streamflow and specific conductance were measured, June and October 2010, upper Brazos River Basin, Texas.
6 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Description of Study Area

The study area is the part of the upper Brazos River 

Basin in Texas from the Texas-New Mexico State line 

boundary in Bailey, Cochran, and Parmer Counties, Tex., 

downstream to near Waco Tex., in McLennan County, Tex. 

(fig. 1). The following subbasins compose the study area: 

Salt Fork Brazos River Basin, Double Mountain Fork 

Brazos River Basin, Clear Fork Brazos River Basin, North 

Bosque River Basin, and the Brazos River Basin (main stem) 

(including its tributaries) (figs. 4–8, respectively).

The headwaters of Salt Fork Brazos River (hereinafter 

Salt Fork) and the Double Mountain Fork Brazos River 

(hereinafter Double Mountain Fork) are small ephemeral 

streams such as Running Water Draw and Blackwater Draw, 

which drain relatively large amounts of land but do not 

produce much streamflow (U.S. Geological Survey, 2009). 

Running Water Draw flows into the White River in Floyd 

County, Tex., and the White River in turn combines with other 

small ephemeral streams to form the Salt Fork in Crosby 

County, Tex. The main reservoir in the Salt Fork Basin is the 

White River Reservoir on the White River east of Lubbock 

(fig. 4). Lubbock is in the Double Mountain Fork Basin 

(fig. 5); it has an average annual rainfall of 18 inches (in.) 

(National Weather Service, 2009). Blackwater Draw 

combines with Yellow House Draw in Lubbock County, Tex., 

to form the North Fork Double Mountain Fork Brazos River 

(fig.1). The main reservoir in the Double Mountain Fork Basin 

is Lake Alan Henry southeast of Lubbock on the South Fork 

Double Mountain Fork Brazos River (fig. 5).The Double 

Mountain Fork begins in Kent County at the confluence of the 

North and South Forks of the Double Mountain Fork Brazos 

River. The contributing drainage areas of the Salt Fork and 

Double Mountain Fork Basins are estimated as 2,496 square 

miles (mi2) and 1,864 mi2,respectively (U.S. Geological 

Survey, 2009). 

The Seymour, Ogallala, Edwards-Trinity (High Plains), 

Dockum, and Blaine aquifers underlie parts of the Salt Fork 

and Double Mountain Fork Basins, with the Ogallala the 

most widespread aquifer underlying these basins (fig. 2). The 

dissolved-solids concentration in the Ogallala aquifer are 

generally less than 500 milligrams per liter (mg/L) in the Salt 

Fork and Double Mountain Fork Basins; in some areas of 

Texas concentrations of dissolved-solids concentrations in the 

Ogallala aquifer exceed 1,000 mg/L but are generally 

less than 3,000 mg/L (Ryder, 1996). The Edwards-Trinity 

(High Plains) aquifer is hydrologically connected to the 

overlying Ogallala aquifer and flows in a general southeast 

direction (Ashworth and Hopkins, 1995). Water from the 

Edwards-Trinity (High Plains) aquifer usually is slightly 

to moderately saline (dissolved-solids concentrations are 

3,000 to 10,000 mg/L), but the chemical quality is suitable 

for irrigation and secondary oil recovery (Ryder, 1996). 

The chemical quality of the groundwater from the Seymour 

aquifer is extremely variable. Concentrations of dissolved 

solids range from 300 to 3,000 mg/L; most values are between 

400 and 1,000 mg/L (Ryder, 1996).The Dockum aquifer 

underlies parts of the Ogallala aquifer in the Salt Fork Basin, 

and dissolved-solids concentration of the water ranges from 

less than 100 to more than 4,000 mg/L (Ryder, 1996). Water 

in the Blaine aquifer is primarily found in numerous solution 

channels formed by dissolved evaporite deposits of anhydrite 

and halite. As water recharged to the aquifer moves along 

solution channels, dissolved solids from the evaporite deposits 

increase the salinity, resulting in relatively saline groundwater. 

Dissolved-solids concentrations in the Blaine increase with 

depth of the aquifer and in natural discharge areas along 

surface drainages and are as high as almost 10,000 mg/L. 

The primary use of groundwater from the Blaine aquifer is 

irrigation of highly salt-tolerant crops (Ashworth and 

Hopkins, 1995).

The headwaters of the Clear Fork Brazos River 

(hereinafter Clear Fork) are in Scurry County, Tex. The 

Clear Fork Basin has three large reservoirs: Lake Fort 

Phantom Hill, Lake Stamford, and Hubbard Creek Reservoir 

(fig. 6). Abilene, Tex., near Lake Fort Phantom, has an average 

annual rainfall of 24 in. (National Weather Service, 2009). The 

Clear Fork flows into the Brazos River in Young County, Tex. 

The estimated contributing drainage area of the Clear Fork 

Basin is 5,697 mi2 (U.S. Geological Survey, 2009). 

The Clear Fork Basin overlies parts of the Seymour and 

Blaine aquifers (figs. 2–3). The Seymour aquifer is composed 

of discontinuous beds of poorly sorted alluvial material 

(Ashworth and Hopkins, 1995) and underlies the Clear Fork 

Basin in Fisher, Jones, Knox, and Haskell Counties. The 

chemical quality of water in this alluvial aquifer ranges from 

fresh to slightly saline. In some areas, the water is hard and 

unsuitable for some uses because it contains dissolved-solids 

concentrations in excess of 2,500 mg/L (Ryder, 1996). The 

part of the Seymour aquifer in Haskell and Knox Counties, 

Tex., is the largest continuous part of the aquifer and the most 

intensively developed. Dissolved-solids concentrations range 

from about 300 to 3,000 mg/L in the Seymour aquifer; most 

values are between 400 and 1,000 mg/L (Ryder, 1996). Water 

from the Blaine aquifer in the Clear Fork Basin is generally 

not suitable for public supply or for many industrial uses 

because of its mineral content. Concentrations of dissolved 

solids measured in water from the Blaine aquifer are generally 

between 2,000 and 6,000 mg/L (Ryder, 1996). 

The headwaters of the North Bosque River are in Erath 

County, Tex. The North Bosque River flows into the Brazos 

River in McLennan County, Tex. (figs. 1, 8). The North 

Bosque Basin has an estimated contributing drainage area of 

1,146 mi2 (U.S. Geological Survey, 2009). 

The Trinity aquifer underlies the entire North Bosque 

Brazos River Basin (figs 2–3). Dissolved-solids concentrations 

in water from the Trinity aquifer typically range from 500 

to 1,500 mg/L (Ryder, 1996). The average annual rainfall of 

Stephenville, Tex. (near the headwaters of the North Bosque 

River), is 30 in., and the average annual rainfall of Waco (near 

the outlet of the North Bosque River basin) is 36 in. (National 

Weather Service, 2009). The North Bosque River flows into 

the western end of Waco Lake (fig. 7).
Introduction 

7

Figure 4. Sites where streamflow and specific conductance were measured in June and October 2010, Salt Fork Brazos River Basin, Texas.

SF-1

SF-2

SF-3

SF-4

SF-5

SF-6

SF-7 SF-9

SF-8

White River

Reservoir

Running Catfish Draw

Water

Draw

White River

Salt

Fork

Duck

Creek

Croton

Creek Short Creek

Brazos

River

TEXAS

NEW

MEXICO

70

207

208

70

70

214

86

70

194

27

27

83

70

385

60

380 380

60

RR 261

FM 784

FM 2284

82

FM 2320

Petersburg

Lorenzo Ralls

Crosbyton

Hale 

Center

Hart

Lockney

Dimmitt

Plainview

Edmonson

Olton

Floydada

Sandhill

Dickens

Spur

Clairemont

Jayton

Aspermont

100°30'

101°00'

101°30'

102°00'

102°30' 103°00'

103°30'

34°30'

34°00'

33°30'

33°00'

EXPLANATION

River basin boundaryGaining reachEphemeral streamPerrenial streamMeasurement site and site identifier—See table 2Salt Fork Brazos River SF-4

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Texas Centric Mapping System–Albers Equal Area Projection, Unitin Meters, North American Datum of 1983

0 40 80 MILES0 40 80 KILOMETERS

Brazos River

Double Mountain 

Fork Brazos River

Salt Fork 

Brazos River

Clear Fork 

Brazos River

North Bosque 

River

LOCATION MAP
8 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Figure 5. Sites where streamflow and specific conductance were measured in June and October 2010, Double Mountain Fork Brazos River Basin, Texas.

Rough

Creek

Yellow 

Blackwater

Draw

Draw

Double Mountain 

Fork Brazos River

North Fork Double

Mountain Fork Brazos River

South Fork Double 

Mountain Fork Brazos River

House

Lake Alan

Henry

DMF-1

DMF-2

DMF-3

DMF-4

DMF-5 DMF-6

DMF-7

DMF-8

Lubbock

Justiceburg

Post

Aspermont

Rotan

Rule

Abernathy

Shallowater

TEXAS

NEW MEXICO

FM 179

FM 1294

FM 400

100°00'

101°00'

102°00'

103°00'

34°00'

33°00'

Treated-effluent inflows from upstream wastewater treatment plant

84

84

60

84

62

87

84

380 380

70

385

62

380

83

207

27

193

208

114

114

92

214

70

287

Brazos River

Double Mountain 

Fork Brazos River

Salt Fork 

Brazos River

Clear Fork 

Brazos River

North Bosque 

River LOCATION MAP

EXPLANATION

Municipal groundwater inflowsRiver basin boundaryEphemeral streamPerrenial streamGaining reachLosing reachMeasurement site and site identifier—See table 2Double Mountain Fork Brazos RiverWastewater-treatment plant

DMF-1

0 40 80 MILES0 40 80 KILOMETERS

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Texas Centric Mapping System–Albers Equal Area Projection, Unitin Meters, North American Datum of 1983
Introduction 

9

Figure 6. Sites where streamflow and specific conductance were measured in June and October 2010, Clear Fork Brazos River Basin, Texas.

FM 1812

CR 509

FM 578

Haskell

Stamford

Hamlin

Anson

Lueders

Roby Albany

Sweetwater Merkel

Baird Cisco

Abilene

Roscoe

Rotan

Breckenridge

Noodle

Nugent

Hawley

Fort Griffin

Eliasville

Crystal

Falls

Foyle Creek

Lake

Stamford 

Lake

Fort 

Phantom

Hill 

Hubbard

Creek Reservoir

nu G

l o

s

su

keer C

Clear

Fork

Brazos

River

Battle

Creek

Sandy

Creek Creek

Deep

Hubbard

Creek

Salt Prong

Hubbard Creek

Mulberry 

Elm Creek

Deadman

Creek Creek Bitter

Sweetwater

Creek Cottonwood

Creek Clear

Fork Brazos River

California

Thompson Creek

Creek

Paint Creek

Creek

6

6

6

67

70

6

70

92

283

351

20

20

20

277

380

83

84

180

83

183

277

277

283

180

83

183

180

83

283

84

Paint Creek

Brazos River

Double Mountain 

Fork Brazos River

Salt Fork 

Brazos River

Clear Fork 

Brazos River

North Bosque 

River

LOCATION MAP

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Texas Centric Mapping System–Albers Equal Area Projection, Unitin Meters, North American Datum of 1983

99°00'

100°00'

33°00'

32°30'

0 40 MILES0 40 KILOMETERS 20

20

EXPLANATION

River basin boundaryEphemeral streamPerrenial streamGaining reachLosing reachMeasurement site and site identifier—See table 2Clear Fork Brazos RiverWastewater-treatment plants

CF-19
10 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Figure 7. Sites where streamflow and specific conductance were measured in June and October 2010, North Bosque River Basin, Texas.

NB-2

NB-1

NB-4

NB-3

NB-7

NB-8

NB-10

NB-6

NB-9

NB-5

North

Bosque

River

North Fork

North Bosque River 

Middle

East Bosque

River 

Meridian 

Neils 

Hog

Creek

Spring

Creek

Creek

Creek

River

Bosque

Stephenville

Dublin

Hico

Meridian

Clifton

Crawford

McGregor

Valley Mills China Springs

Iredell

Walnut

Springs

317

22

220

108

6

6

6

281

281

67

67

FM 927 32°00'

31°30'

97°30'

98°00'

Brazos River

Double Mountain 

Fork Brazos River

Salt Fork 

Brazos River

Clear Fork 

Brazos River

North Bosque 

River

LOCATION MAP

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Texas Centric Mapping System–Albers Equal Area Projection, Unitin Meters, North American Datum of 1983

84

EXPLANATION

River basin boundaryEphemeral streamPerrenial streamGaining reachMeasurement site and site identifier—See table 2North Bosque RiverWastewater-treatment plant

NB-6

Waco Waco Lake

0 40 MILES0 40 KILOMETERS

20

20
Introduction 11 Figure 8. Sites where streamflow and specific conductance were measured in June and October 2010, main stem of the Brazos River and tributaries to the main stem, Texas. 

97°00'

98°00'

99°00'

100°00'

33°00'

FM 2284

FM 3028

FM 2940

FM 1858

!

BMS-1

BMS-2

BMST-2

BMS-3

BMST-3

BMST-4

BMS-4

BMS-5

BMST-5

BMS-6

BMST-7

BMS-7

BMST-9

BMST-8 BMST-10

BMST-13

BMST-14

BMST-6

BMST-12

BMS-8

BMST-1

BMST-11

Graham

Mineral

Wells

Ranger Granbury

Hillsboro

West

Ross

Munday

Knox

City

Benjamin

Newcastle

Olney

Seymour

South

Bend

Palo

Pinto

Dennis

Glen

Rose

Aquilla

Cleburne

Blum

Sturdivant

New 

Salem

Brock Junction

FM 129

Lake Graham

North

Croton

Creek

Lake

Creek

Miller

Creek

Boogy

Creek

North

Elm

Creek

Brazos River

Salt Creek

Possum 

Kingdom

Lake

Cedar

Creek

Creek

Palo

Pinto Caddo Creek

Creek

West ForkKeechi Creek

Rock

Creek

Grindstone 

Creek

Lake

Palo

Pinto

South Fork

Palo Pinto 

Creek Barton

Creek

Paluxy River

Squaw Creek

KickapooCreek

Brazos

River

LakeAquilla

Lake

Childress

Creek

Whitney

Steel

Creek

Nolan River

Aquilla 

Hackberry

Creek 

Tehu

Creek

Creek

TradinghouseCreek Reservoir

Lake

Granbury

acana

Brazos

Fork

Mountain

Double

River

Salt

Brazos

Fork

River

Brazos

Fork

River

Clear

Ioni

Brazos

River

Waco

Lake

River

North

Bosque

Squaw

Creek

Lake

Graford

83

84

183

277

377

277

380

377

80

183

283

35

281 67

171

114

337

108

144

174

251

252

533

16

174

171

16

31

22

67

281 ¤

20

Brazos River

Double Mountain 

Fork Brazos River

Salt Fork 

Brazos River

Clear Fork 

Brazos River

North Bosque 

River

LOCATION MAP

EXPLANATION

River basin boundaryEphemeral streamPerrenial streamGaining reachDiversion pipelineMeasurement site and site identifier—See table 2Upper Brazos River main stemUpper Brazos River main stem tributaryWastewater-treatment plant

BMST-2

BMS-4

0 40 80 MILES0 40 80 KILOMETERS

340

Base from U.S. Geological Survey digital data,Water, road, and boundary features from TheNational Atlas of the United States digital data 1:2,000,000, Hydrologic Unit Code digital data 1:250,000, Texas Centric Mapping System–Albers Equal Area Projection, North American Datum of 1983

Waco

32°00'
12 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

The Brazos River main stem is formed by the confluence 

of the Salt Fork and Double Mountain Fork in Stonewall 

County, Tex. Major reservoirs in the watershed in downstream 

order are Possum Kingdom Lake, Lake Palo Pinto, Lake 

Granbury, Lake Aquilla, and Waco Lake. There are three 

major reservoirs on the Brazos River main-stem north of 

Waco: Possum Kingdom Lake near Graford, Tex., Lake 

Granbury near Granbury, Tex., and Lake Whitney. There 

are several smaller reservoirs on tributaries to the Brazos. 

Four streamflow-gaging stations are located in this reach on 

the main stem of the Brazos River (fig. 1, table 1) for which 

long-term data exist. The Brazos River Basin (main stem) has 

an estimated contributing drainage area of 20,007 mi2 plus an 

additional 9,566 mi2 that is noncontributing (U.S. Geological 

Survey, 2009). 

The Trinity and Woodbine aquifers (figs. 2–3) underlie 

the Brazos River Basin (main stem) approximately from 

Glen Rose, Tex., downstream to Waco. The Trinity aquifer is 

mostly composed of alluvium (sand and gravel) and marine 

carbonate limestone (Ashworth and Hopkins, 1995). 

Although the outcrop regions of the Trinity aquifer are 

favorable for the infiltration of precipitation, groundwatermovement rates are typically no more than a few feet per year 

(Cronin and others, 1963). The concentration of dissolved 

solids in water from the Trinity aquifer typically ranges from 

500 to 1,500 mg/L (Ryder, 1996). The Trinity aquifer is one 

of the most areally extensive and highly used aquifers in 

Texas. Its primary use is to supply water for municipalities, 

but the aquifer also is used for irrigation, livestock, and 

other rural domestic purposes. Water from the Woodbine 

aquifer in the outcrop area has an average dissolved-solids 

concentration of about 550 mg/L; the concentration increases 

downdip to more than 3,000 mg/L (Ryder, 1996). A small part 

of the study area receives groundwater from the Brazos River 

alluvium aquifer, which is present in the main channel of the 

Brazos River from Waco north to Lake Whitney (Texas Water 

Development Board, 2007a). 

Methods

Streamflow was measured using methods approved by 

the USGS (Turnipseed and Sauer, 2010). Specific-conductance 

values were measured using methods approved by the USGS 

(U.S. Geological Survey, variously dated). Base flow was 

estimated by applying hydrograph separation techniques 

(Sloto and Crouse, 1996) to historical data from 11 long-term 

streamflow-gaging sites in the study area (table 1). At most 

sites where streamflow was measured, specific-conductance 

values were determined from grab samples collected from the 

centroid of flow or measured by placing a hand-held meter 

in the centroid of flow. Meters used to measure specificconductance values were calibrated following established 

guidelines (U.S. Geological Survey, variously dated). 

Specific-conductance data collected in conjunction with 

streamflow measurements in 2010 are used to help understand 

observed changes in flow in gaining and losing reaches. 

Analyses of streamflow gains and losses were done for each 

of the five subbasins composing the upper Brazos River 

Basin. The basin designated as the main stem of the Brazos 

River was subdivided into four reaches separated by three 

reservoirs: upstream from Possum Kingdom Reservoir, from 

the outflow of Possum Kingdom Reservoir to the headwaters 

of Lake Granbury, from the outflow of Lake Granbury to 

the headwaters of Lake Whitney, and from the outflow from 

Lake Whitney to the mouth of the North Bosque River on 

the Brazos River north of Waco, Tex. Synoptic-streamflow 

measurements were used to estimate streamflow gains 

and losses in the five subbasins. The specific-conductance 

data collected concurrently with synoptic-streamflow 

measurements were used in the analyses of streamflow 

gains and losses; specific conductance is an indicator of the 

concentration of dissolved solids in the water, so changes in 

specific conductance can help identify the reasons for gains or 

losses in streamflow. 

Hydrograph Separation and Trend Analysis

Hydrograph separation is the method of separating 

measured streamflow into components resulting from direct 

surface runoff or from groundwater discharge (base flow). 

Hydrograph separation was done using the USGS computer 

program Hydrograph Separation and Analysis (HYSEP) 

(Sloto and Crouse, 1996). HYSEP provides three methods of 

hydrograph separation that are referred to in literature as the 

fixed-interval, sliding-interval, and local-minimum methods 

(Sloto and Crouse, 1996). The local-minimum method was 

selected for this analysis. The local-minimum method is 

an algorithm that systematically draws connecting lines 

between the low points of the streamflow hydrograph; an 

example of the hydrograph separation for USGS streamflowgaging station 08089000 Brazos River near Palo Pinto, Tex. 

(hereinafter the Brazos Palo Pinto gage), for the 1978 water 

year is provided (fig. 9). 

The data used in HYSEP were historical (water years 

1966–2009) streamflow from 11 USGS streamflow-gaging 

stations in the upper Brazos River Basin (table 1) with the 

exception of data from USGS streamflow-gaging stations 

08082500 Brazos River at Seymour, Tex. (1967–2009), and 

08090800 Brazos River near Dennis, Tex. (1969–2009). The 

HYSEP program makes the hydrograph separation process 

more precise by removing inconsistencies inherent in manual 

methods. The input to the HYSEP program consisted of the 

daily mean streamflow values measured at each streamflowgaging station. Output from the program includes the two 

components of the annual mean streamflow—annual mean 

surface runoff and annual mean base flow. Additionally, 

HYSEP provides the base-flow index (BFI), which is the 
Methods 13

Table 1. U.S. Geological Survey streamflow-gaging stations in the upper Brazos River Basin that provided data for hydrographic 

separation, water years 1966–2009 (October 1965 through September 2009).

[P-value considered statistically significant if <0.05; mi2, square miles; <, less than]

Station 

number Station name County

Contributing 

drainage 

area (mi2)

Begin and end year1

Period 

of record 

used

Mann Kendall 

upward trend 

analysis (gaining)

First 

unregulated

First 

regulated

Last 

year2 p-value

Statistically 

significant

08082000

Salt Fork Brazos 

River near 

Aspermont, Tex.

Stonewall 2,500 1940 1964 2009 1966–2009 0.26 No

08080500

Double Mountain 

Fork Brazos 

River near 

Aspermont, Tex.

Stonewall 1,860 1925 -- 2009 1966–2009 <0.01 Yes

08084000

Clear Fork 

Brazos River at 

Nugent, Tex.

Jones 2,200 1925 1940 2009 1966–2009 0.81 No

08085500

Clear Fork Brazos 

River at Fort 

Griffin, Tex.

Shackelford 3,990 1925 1940 2009 1966–2009 0.68 No

08095000

North Bosque 

River near 

Clifton, Tex.

Bosque 968 1924 1968 2009 1966–2009 0.69 No

08082500 Brazos River at 

Seymour, Tex. Baylor 5,970 1925 1974 2009 1967–2009 0.10 No

08088000

Brazos River 

near South 

Bend, Tex.

Young 13,100 1939 1962 2009 1966–2009 0.34 No

08089000

Brazos River 

near Palo 

Pinto, Tex.

Palo Pinto 14,200 1925 1941 2009 1966–2009 <0.01 Yes

08090800 Brazos River near 

Dennis, Tex. Parker 15,700 -- 1969 2009 1969–2009 <0.01 Yes

08091000 Brazos River near 

Glen Rose, Tex. Somervell 16,300 1924 1941 2009 1966–2009 0.74 No

08091500 Paluxy River at 

Glen Rose, Tex. Somervell 410 1925 1982 2009 1966–2009 0.26 No

1

 Record might not be continuous from begin year to end year. Partial-record data exist for some stations outside period of record indicated. 

2

 Inventory includes data through 2009 water year. Most stations with end year of 2009 are still in operation.
14 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

1

10

100

1,000

10,000

100,000

Measured flowEstimated base flow

d

n

o

c

e

s

r

e

p

t

e

e

f

c

i

b

u

c

n

i

,

e

g

r

a

h

c

s

i

D

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

1977 1978

Date

Figure 9. Hydrograph separation of streamflow for U.S. Geological Survey streamflow-gaging station 08089000 Brazos River near Palo Pinto, Texas, 1978 water year.
Methods 15

ratio of the annual mean base flow to the annual mean 

streamflow. The BFI was used to graphically compare four 

pairings of streamflow data (hydrographs) from eight Brazos 

River streamflow-gaging stations, where each pair of stations 

were on the same stream reach with no reservoirs between 

them, or paired in adjacent basins with similar hydrologic 

characteristics. The graphical comparisons for the stations 

on the same reach indicate whether the reach between two 

stations is gaining or losing flow. The graphical comparisons 

for stations in adjacent basins of similar hydrologic 

characteristics indicate which basin has a larger contribution 

of the total flow as base flow measured at the site.

Wahl and Wahl (1995) state that caution is needed when 

applying hydrograph separation to streamflow resulting from 

short-duration storms or to streamflow affected by upstream 

regulation, such as reservoir releases, and there are large 

number of reservoirs regulating streamflow in the study area. 

Reservoir releases in the study area are often made in response 

to storm runoff, so from the perspective of the HYSEP model, 

a reservoir release differing from base flow is categorized as 

storm runoff. After HYSEP was used to make hydrograph 

separation computations, the results were analyzed and 

judgments made in an attempt to determine whether upward 

trends in flow over time were a result of increases in reservoir 

releases rather than increases in base flow. When judged 

necessary, HYSEP program input can be adjusted by varying 

the runoff-timing and rerunning the program. This iterative 

process was continued until periods of reservoir releases were 

categorized by HYSEP as storm runoff and not as base flow. In 

some cases where the flow in a reach is regulated by reservoir 

releases, additional analyses beyond the scope of this study 

would be required before apparent streamflow trends can be 

characterized as indicative of changes in base flow over time. 

Results of the HYSEP analysis were further tested for 

trends in BFI values by using the Mann-Kendall trend analysis 

test. The Mann-Kendall trend test is a nonparametric test 

used to analyze for changes in the median BFI for each site 

over time (Helsel and Hirsch, 2002). When the p-value for 

the Mann-Kendall test was less than 0.05, the identified trend 

(gaining or losing) was considered statistically significant.

Data Collection

To compute streamflow gains and losses, synoptic 

streamflow measurements were made in the spring and fall of 

2010. The measurement sites consisted of long-term USGS 

streamflow-gaging stations (identified with 8-digit station 

numbers) and temporary measurement stations (identified with 

15-digit station numbers). Specific-conductance values were 

measured at most sites where streamflow was measured 

(table 2). The first set of synoptic measurements were made 

during June 6–9, 2010 (the June survey), and the second in 

October 16–19, 2010 (the October survey). Early June (spring) 

and mid October (fall) were selected as the data-collection 

periods because they were representative of low-flow 

conditions in different seasons. Hydrologic conditions in the 

spring and fall typically are different; spring is usually wetter 

than fall in the study area (Texas State Climatologist, 2010). 

Prior to the June survey, precipitation during the first 5 months 

of 2010 varied in the upper Brazos River Basin. Precipitation 

measured at Abilene, Tex. (3.6 in.), was 127 percent of normal 

for May; however, precipitation measured at Waco, Tex., 

(0.89 in.) was only 20 percent of the average for May (Texas 

State Climatologist, 2010). Several days without measureable 

rainfall occurred throughout the study area before the June 

survey. For example, the last time recorded rainfall of more 

than a trace occurred in the study area was on May 17, 2010, 

at Abilene (0.16 in.), and on May 21, 2010, at Waco (0.82 in). 

The month preceding the October survey is usually hotter 

and drier compared to the month preceding the June survey, 

and demand on water resources (pumpage from the river, the 

alluvial aquifer, and the underlying major and minor aquifers) 

is relatively high. Precipitation measured in September 2010 at 

Abilene (2.44 in.) was 84 percent of normal, however, 

9.49 in. was recorded at Waco, which was 330 percent of 

normal (Texas State Climatologist, 2010). Most precipitation 

in September 2010 occurred during the first 8 days of the 

month (National Climatic Data Center, 2010). Prior to the 

October survey, the last substantial rainfall (more than a trace) 

was recorded on September 25, 2010 (0.71 in. at Abilene 

and 0.12 in. at Waco) (National Climatic Data Center, 2010), 

which allowed for 11 to 14 days for streams to return to base 

flow before measurements of streamflow were made. 

In the June survey, streamflow was measured at 58 sites 

that were not on the main stem of the Brazos River (including 

15 observations of no flow), and at 8 on the main stem of the 

Brazos River (table 2). During the October survey, streamflow 

measurements were made at 60 sites that were not on the 

main stem of the Brazos River (including 13 observations of 

no flow), and at 8 sites on the main stem of the Brazos River 

(table 2). Replicate streamflow measurements were made at 

five randomly selected sites for the June survey and at seven 

randomly selected sites for the October survey (table 2). 

Substantial changes in specific-conductance values between 

sites measured during the same set of synoptic measurements 

might indicate inputs to streamflow of water from discharging 

aquifer systems. Hem (1985) states that generally there is a 

strong relation between dissolved solids concentration and 

specific-conductance values as expressed by the equation:

KA = S (1)

where 

 K is specific conductance, in microsiemens 

per centimeter at 25 degrees Celsius,

 S is dissolved solids in milligrams per liter, 

and

 A is a constant ranging from 0.55 and 0.75. 
16 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Table 2. Streamflow and specific-conductance values measured during June and October 2010 in the upper Brazos River 

Basin, Texas.

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; FM, Farm Road; SF, Salt Fork 

Brazos River Basin; no flow, discharge equal to zero; -, no data collected; est., estimated; RR, Ranch Road; SH, State Highway; /, replicate measurement 

except as noted; DMF, Double Mountain Fork Brazos River Basin; Hwy, Highway; CF, Clear Fork Brazos River Basin; CR, County Road; SR, State Route; 

NB, North Bosque River Basin; BMS, Brazos River Main Stem; BMST, Brazos River Main Stem Tributary]

USGS station name

USGS station 

number

Site 

identifier 

(figs. 4–8) Latitude Longitude

Discharge (ft3/s)

Specific

 conductance 

(μS/cm)

June 6-9, 

2010

October 

16-19, 2010

June 6-9, 

2010

October 

16-19, 

2010

Running Water Draw at 

FM 2884 near 

Edmonson, Tex.

341643102013700 SF-1 34°16’44” 102°1’37” no flow no flow - -

Running Water Draw at 

Plainview, Tex.

08080700 SF-2 34°10’44” 101°42’08” no flow no flow - -

Running Water Draw at 

FM 784 at Sandhill, Tex.

335939101293500 SF-3 33°59’40” 101°29’36” no flow no flow - -

White River below falls near 

Crosbyton, Tex.

08080900 SF-4 33°39’58” 101°9’37” 0.06 0.07 (est.) 9,590 1,060

White River at RR 261 near 

Spur, Tex.

332426101030700 SF-5 33°24’26” 101°03’08” no flow 0.05 no flow 2,640

Salt Fork Brazos River at 

SH 208 near Clairemont, Tex.

08080940 SF-6 33°12’26” 100°44’47” 1.06/0.85 2.86 34,450 22,940

Duck Creek at FM 2320 near 

Jayton, Tex.

331608100420100 SF-7 33°16’09” 100°42’02” 1.56 1.75 3,640 3,630

Croton Creek below Short 

Creek near Jayton, Tex.

08081100 SF-8 33°18’23” 100°31’55” - 0.1 - 35,600

Salt Fork Brazos River near 

Aspermont, Tex.

1

08082000 SF-9 33°20’02” 100°14’16” 9.41 10.9/11.5 53,000 48,670

Blackwater Draw at FM 179 

near Abernathy, Tex.

335325101593700 DMF-1 33°53’25” 101°59’38” no flow no flow - -

Yellow House Draw at FM 1294 

at Shallowater, Tex.

334137102005900 DMF-2 33°41’38” 102°00’59” no flow no flow - -

North Fork Double Mountain 

Fork Brazos River at FM 400 

near Lubbock, Tex.

333047101393300 DMF-3 33°30’48” 101°39’34” 22.83/6.90 2.28/7.86 2,000 2,030

North Fork Double Mountain 

Fork Brazos River at FM 207 

near Post, Tex.

331909101232900 DMF-4 33°19’10” 101°23’30” 2.78 3.17 - 1,110

Double Mountain Fork Brazos 

River at Justiceburg, Tex.

08079600 DMF-5 33°02’18” 101°11’50” no flow 0.20 - 14,190

Double Mountain Fork Brazos 

River near Rotan, Tex.

08080000 DMF-6 32°55’50” 100°29’17” 36.8 22.8/23.5 5,690 7,950

Double Mountain Fork Brazos 

River near Aspermont, Tex.

1

08080500 DMF-7 33°00’29” 100°10’49” 43.3/41.8 27.3 5,670 7,790

Double Mountain Fork Brazos 

River at Hwy 380 near 

Rule, Tex.

331116099573600 DMF-8 33°11’17” 99°57’36” 52.5 36.5 4,400 7,070
Methods 17

Clear Fork Brazos River near 

Roby, Tex.

08083100 CF-1 32°47’15” 100°23’18” 0.77 1.04 11,200 10,530

Sweetwater Creek at FM 1812 

near Noodle, Tex.

323720100071200 CF-2 32°37’20” 100°07’13” 0.85 1.46 5,000 4,750

Clear Fork Brazos River near 

Noodle, Tex.

08083230 CF-3 32°40’28” 100°04’20” 5.15 6.75 9,030 6,060

Clear Fork Brazos River at 

CR 509 at Hawley, Tex.

323635099495800 CF-4 32°36’36” 99°49’58” 4.39 10.8 7,160 5,470

Mulberry Creek near 

Hawley, Tex.

08083245 CF-5 32°34’03” 99°47’35” no flow no flow - -

Clear Fork Brazos River at 

Nugent, Tex.

1

08084000 CF-6 32°41’24” 99°40’09” 5.64 14.6 5,740 4,590

Deadman Creek near 

Nugent, Tex.

08084100 CF-7 32°40’36” 99°37’04” 19.8 14.1 1,630 1,520

Clear Fork Brazos River at 

Hwy 6 at Lueders, Tex.

324701099362000 CF-8 32°47’41” 99°36’20” 19.8 26.5 2,830 2,690

Clear Fork Brazos River near 

Lueders, Tex.

325732099273200 CF-9 32°57’32” 99°27’33” 20.3 27.1 2,120 2,160

California Creek near 

Stamford, Tex.

08084800 CF-10 32°55’51” 99°38’32” 3.61 4.70 7,200 639

Paint Creek below Lake 

Stamford near Haskell, Tex.

330433099333300 CF-11 33°04’33” 99°33’34” 5.15 5.45 4,500 3,000

Clear Fork Brazos River at 

Fort Griffin, Tex.

1

08085500 CF-12 32°56’04” 99°13’27” 26.1 32.4 2,300 710

Hubbard Creek at Hwy 283 

near Baird, Tex.

322606099230400 CF-13 32°26’07” 99°23’05” no flow no flow - -

Hubbard Creek near 

Albany, Tex.

08086100 CF-14 32°43’58” 99°08’25” no flow no flow - -

Sandy Creek at Hwy 6 at 

Cisco, Tex.

322424098591200 CF-15 32°26’17” 98°58’51” 0.06 no flow 533 -

Big Sandy Creek near 

Breckenridge, Tex.

08086300 CF-16 32°39’54” 99°00’01” 0.88 no flow 685 -

Hubbard Creek at FM 578 at 

Crystal Falls, Tex.

325310098543200 CF-17 32°53’11” 98°54’32” no flow no flow - -

Gonzales Creek near 

Breckenridge, Tex.

324812098535800 CF-18 32°48’12” 98°53’59” no flow 0.24 - 2,540

Table 2. Streamflow and specific-conductance values measured during June and October 2010 in the upper Brazos River 

Basin, Texas.—Continued

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; FM, Farm Road; SF, Salt Fork 

Brazos River Basin; no flow, discharge equal to zero; -, no data collected; est., estimated; RR, Ranch Road; SH, State Highway; /, replicate measurement 

except as noted; DMF, Double Mountain Fork Brazos River Basin; Hwy, Highway; CF, Clear Fork Brazos River Basin; CR, County Road; SR, State Route; 

NB, North Bosque River Basin; BMS, Brazos River Main Stem; BMST, Brazos River Main Stem Tributary]

USGS station name

USGS station 

number

Site 

identifier 

(figs. 4–8) Latitude Longitude

Discharge (ft3/s)

Specific

 conductance 

(μS/cm)

June 6-9, 

2010

October 

16-19, 2010

June 6-9, 

2010

October 

16-19, 

2010
18 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Clear Fork Brazos River at 

FM 578 at Crystal Falls, Tex.

325406098535700 CF-19 32°54’07” 98°53’57” 26.3 29.9/31.3 1,980 653

North Fork North Bosque 

River at State Route 108 

near Stephenville, Tex. 

321513098133100 NB-1 32°15’14” 98°13’31” no flow no flow - -

North Bosque River at Hico, 

Tex.

08094800 NB-2 31°58’35” 98°01’57” 11.7 4.16 414 522

North Bosque River at Hwy 6 

near Iredell, Tex.

315839097534200 NB-3 31°58’40” 97°53’43” 14.2 4.85 292 429

East Bosque River at FM 927 

near Walnut Springs, Tex.

320106097465700 NB-4 32°01’06” 97°46’58” 0.87 0.26 - 495

North Bosque River at Hwy 22 

at Meridian, Tex.

315510097394300 NB-5 31°55’10” 97°39’43” 26.1 7.60/7.59 - 459

Meridian Creek at Hwy 6 near 

Clifton, Tex.

314842097364100 NB-6 31°48’42” 97°36’42” 10.3/8.37 3.70/3.52 407 433

North Bosque River near 

Clifton, Tex.

1

08095000 NB-7 31°47’09” 97°34’04” 47.9 17.6 522 510

Neils Creek at Hwy 6 near 

Valley Mills, Tex.

314136097320700 NB-8 31°41’37” 97°32’07” 18.2 6.84 486 464

North Bosque River at Valley 

Mills, Tex.

08095200 NB-9 31°40’10” 97°28’09” 86.7 39.1 514 539

North Bosque River near China 

Springs, Tex.

313830097220100 NB-10 31°38’30” 97°22’01” 103/107 41.4 464 511

Brazos River at Hwy 143/222 

near Knox City, Tex.

332533099544100 BMS-1 33°25’33” 99°54’41” 86.2 61.9 15,070 17,550

Brazos River at Seymour, Tex. 108082500 BMS-2 33°34’51” 99°16’02” 142 93.7 16,630 14,680

Brazos River near South 

Bend, Tex.

1

08088000 BMS-3 33°01’27” 98°38’37” 163 127 8,940 8,600

Brazos River near Graford, Tex. 08088610 BMS-4 32°51’29” 98°24’41” 105 156 2,510 3,080

Brazos River near Palo 

Pinto, Tex.

1

08089000 BMS-5 32°51’45” 98°18’08” 138/132 164 2,410 3,090

Brazos River near Dennis, Tex. 108090800 BMS-6 32°36’56” 97°55’32” 192 172 - 2,970

Brazos River near Glen 

Rose, Tex.

1

08091000 BMS-7 32°15’30” 97°42’10” 99 62.4 - 2,260

Brazos River near Aquilla, Tex. 08093100 BMS-8 31°48’46” 97°17’52” 252 252 998 2,380

Lake Creek at FM 2070 near 

Seymour, Tex.

333323099263000 BMST-1 33°33’23” 99°26’30” - 0.33 - 3,950

Table 2. Streamflow and specific-conductance values measured during June and October 2010 in the upper Brazos River 

Basin, Texas.—Continued

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; FM, Farm Road; SF, Salt Fork 

Brazos River Basin; no flow, discharge equal to zero; -, no data collected; est., estimated; RR, Ranch Road; SH, State Highway; /, replicate measurement 

except as noted; DMF, Double Mountain Fork Brazos River Basin; Hwy, Highway; CF, Clear Fork Brazos River Basin; CR, County Road; SR, State Route; 

NB, North Bosque River Basin; BMS, Brazos River Main Stem; BMST, Brazos River Main Stem Tributary]

USGS station name

USGS station 

number

Site 

identifier 

(figs. 4–8) Latitude Longitude

Discharge (ft3/s)

Specific

 conductance 

(μS/cm)

June 6-9, 

2010

October 

16-19, 2010

June 6-9, 

2010

October 

16-19, 

2010
Methods 19

Millers Creek at Hwy 183/283 

near Seymour, Tex.

332744099144300 BMST-2 33°27’45” 99°14’44” no flow no flow - -

Salt Creek at Olney, Tex. 08088100 BMST-3 33°22’14” 98°44’41” 0.06 0.05 14,240 7,870

Salt Creek at Hwy 380 near 

Newcastle, Tex.

331140098390300 BMST-4 33°11’41” 98°39’04” 12.8 2.16 523 393

Palo Pinto Creek at FM 129 

near New Salem, Tex.

323932098072300 BMST-5 32°39’33” 98°07’23” 4.56 2.20/3.19 578 450

Rock Creek at FM 3028 near 

Sturdivant, Tex.

324456098025900 BMST-6 32°44’56” 98°02’59” 2.28 1.10 - 464

Grindstone Creek at I-20 near 

Brock Junction, Tex.

324151097581900 BMST-7 32°41’51” 97°58’20” 0.05 0.06 - 1,160

Paluxy River at Glen Rose, Tex. 108091500 BMST-8 32°13’53” 97°46’37” 35.4 9.84 - 508

Squaw Creek near Glen 

Rose, Tex.

08091750 BMST-9 32°16’12” 97°47’12” 15.6 4.45 - 4,470

Nolan River at Blum, Tex. 08092000 BMST-10 32°09’02” 97°43’56” 6.63 8.76 - 812

Childress Creek at FM 2490 

near Waco, Tex.

314220097174100 BMST-11 31°42’21” 97°17’41” 3.54 4.33/5.02 313 310

Aquilla Creek above 

Aquilla, Tex.

08093360 BMST-12 31°53’43” 97°12’10” 2.26 14.0 - 491

Cobb Creek near Aquilla, Tex. 315300097114200 BMST-13 31°53’01” 97°11’43” no flow no flow - -

Aquilla Creek at FM 1858 

near Ross, Tex.

08093560 BMST-14 31°43’33” 97°12’39” 15.5 22.1 967 446

1

 Data used on Hydrograph Separation and Analyses (HYSEP) (Sloto and Crouse, 1996) to calculate base flow index values.

Table 2. Streamflow and specific-conductance values measured during June and October 2010 in the upper Brazos River 

Basin, Texas.—Continued

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; FM, Farm Road; SF, Salt Fork 

Brazos River Basin; no flow, discharge equal to zero; -, no data collected; est., estimated; RR, Ranch Road; SH, State Highway; /, replicate measurement 

except as noted; DMF, Double Mountain Fork Brazos River Basin; Hwy, Highway; CF, Clear Fork Brazos River Basin; CR, County Road; SR, State Route; 

NB, North Bosque River Basin; BMS, Brazos River Main Stem; BMST, Brazos River Main Stem Tributary]

USGS station name

USGS station 

number

Site 

identifier 

(figs. 4–8) Latitude Longitude

Discharge (ft3/s)

Specific

 conductance 

(μS/cm)

June 6-9, 

2010

October 

16-19, 2010

June 6-9, 

2010

October 

16-19, 

2010
20 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Streamflow Gain and Loss Computation

The amount of streamflow that varies from the upstream 

end to the downstream end of a reach can be categorized as 

gain, loss, or no change in base flow for that particular reach. 

This amount is computed by using the following equation:

Qu + Qt + Qr = Qd + Qw + Qe + Qg (2)

where

 Qu is streamflow in at upstream end of reach,

 Qt is streamflow from tributaries into reach,

 Qr is return flows to reach,

 Qd is streamflow out at downstream end of 

reach,

 Qwis withdrawals from reach,

 Qe is evapotranspiration from reach, and

 Qg is gain (positive) or loss (negative) in 

reach.

Thus,

Qg = Qu +Qt + Qr – Qd –Qw –Qe (3) 

The study area was divided into the five subbasins 

described in the Description of Study Area section for the 

purpose of measuring streamflow gains or losses, and each 

subbasin has a main-stem stream. Any tributary inflows 

to the main stem in each subbasin were measured (many 

tributaries were dry streambeds). However, return flows (Qr), 

withdrawals (Qw), and evapotranspiration (Qe) generally were 

not measured, and those components were excluded from 

equation 3.The error in Qg associated with these exclusions 

is believed to be minor when compared to potential errors 

associated with the flow measurements. Return flows of 

treated effluent (wastewater) from the following cities in the 

study area were included in the analysis: Abilene, Lubbock, 

Breckenridge, Graham, Stephenville, and Meridian, Tex. 

Quality Assurance

For this report, a stream reach is characterized as 

verifiably gaining or losing only when the difference between 

streamflow at the upstream and downstream measuring 

sites that define the reach is greater than the potential error 

associated with the streamflow measurements. Measurement 

error is based on the rating of the streamflow measurement 

(excellent, good, fair, or poor) by the streamgager (Turnipseed 

and Sauer, 2010). The rating is based on factors such as 

orientation of cross section relative to the channel, number 

of depth and velocity observations, cross-section uniformity, 

velocity homogeneity, streambed conditions, and other 

factors that might affect the accuracy of the measurement. 

Measurements were assigned a rating based on USGS 

guidelines (Turnipseed and Sauer, 2010) of excellent, within 

2 percent of the actual flow; good, within 5 percent; fair, 

within 8 percent; and poor, differs from the actual flow by 

more than 8 percent. The potential errors associated with each 

pair (upstream and downstream) of streamflow measurements 

for a given reach were summed to obtain the potential 

composite error for each measurement. USGS guidelines 

(Turnipseed and Sauer, 2010) for operation and maintenance 

of streamflow measuring equipment and techniques of making 

streamflow measurements were followed. Because most 

streamflow measurements were rated as fair or better, reaches 

were identified as gaining or losing if the measured differences 

were more than 8 percent. 

Replicate streamflow measurements were made at 

randomly selected sites during the June and October surveys 

(table 2). Replicate streamflow measurements during 

June 6–9, 2010, were made at USGS stations 08080940 Salt 

Fork Brazos River at State Highway 208 near Clairemont, 

Tex., 314842097364100 Meridian Creek at Highway 6 near 

Clifton, Tex., 313830097220100 North Bosque River near 

China Springs, Tex., 08080500 Double Mountain Fork Brazos 

River near Aspermont, Tex., and 08089000 Brazos River 

near Palo Pinto, Tex. Replicate streamflow measurements 

during October 16–19, 2010, were made at the following 

USGS stations: 08082000 Salt Fork Brazos River near 

Aspermont, Tex., 08080500 Double Mountain Fork Brazos 

River near Rotan, 325406098535700 Clear Fork Brazos River 

at Farm Road 578 at Crystal Falls, Tex., 315510097394300 

North Bosque River at Highway 22 at Meridian, Tex., 

314842097364100 Meridian Creek at Highway 6 near Clifton, 

Tex., 323932098072300 Palo Pinto Creek at Farm Road 129 

near New Salem, Tex., and 314220097174100 Childress 

Creek at Farm Road 2490 near Waco, Tex. Two streamflow 

measurements were made in June and October 2010 at USGS 

station 333047101393300 North Fork Double Mountain Fork 

Brazos River at Farm Road 400 near Lubbock, Tex. (site 

DMF–3) to measure differences in streamflow resulting from 

changes in treated-effluent inflows; the Lubbock wastewatertreatment plant discharges effluent upstream from site 

DMF–3 (fig. 5). Consecutive streamflow measurements 

were made upstream and downstream from Farm Road 400 

at site DMF–3.

Base Flow

Analysis of base flow as an index of streamflow (BFI), 

determined by dividing the amount of base flow by the 

total amount of flow each water year, was done at 11 USGS 

streamflow-gaging stations in the upper Brazos River Basin 

for which there were long-term data from water years 1966–

2009 at 9 stations and slightly shorter periods of record at 2 

stations (1967–2009 and 1969–2009) (table 1). The number 
Base Flow 21

of USGS streamflow-gaging stations in each subbasin were as 

follows: one in each the Salt Fork and Double Mountain Fork 

basins, two in the Clear Fork basin, one in the North Bosque 

River basin, and six in the Brazos River Basin (main stem) 

(table 1; appendix 1). 

Salt Fork and Double Mountain Fork Brazos 

River Basin

In the Salt Fork Basin, the BFI was calculated using 

data from USGS streamflow-gaging station 08082000 Salt 

Fork Brazos River near Aspermont, Tex. (hereinafter Salt 

Fork Aspermont gage, site SF-9), which is 27.3 mi upstream 

from the confluence with the Double Mountain Fork north 

of Aspermont (U.S. Geological Survey, 2009). The annual 

BFI for the Salt Fork Aspermont gage ranged from a 

minimum of 0.03 in 2000 to a maximum of 0.46 in 1973 

(fig. 10) with a median BFI value of 0.16. The drainage area 

for this part of the upper Brazos River Basin overlies parts 

of the Seymour and Ogallala major aquifers (fig. 2), as well 

as the Edwards-Trinity (High Plains), Dockum, and Blaine 

minor aquifers (fig. 3). 

In the Double Mountain Fork Basin, the BFI was 

calculated using data from USGS streamflow-gaging 

station 08080500 Double Mountain Fork Brazos River 

near Aspermont, Tex. (hereinafter Double Mountain Fork 

Aspermont gage, site DMF-7) (fig. 11), which is 34.5 mi 

upstream from the confluence of Double Mountain Fork 

Brazos River with the Salt Fork north of Aspermont in 

Stonewall County, Tex. (U.S. Geological Survey, 2009). The 

annual BFI for the Double Mountain Fork Aspermont gage 

ranged from a minimum of 0.01 in 1995 to a maximum of 0.62 

in 2001, and the median BFI was 0.15. This part of the upper 

Brazos River Basin is similar to the Salt Fork Basin in that 

part of the basin overlies sections of the Seymour and Ogallala 

major aquifers (fig. 2) and the Edwards-Trinity (High Plains), 

Dockum, and Blaine minor aquifers (fig. 3). 

The Salt Fork and Double Mountain Fork Basins were 

compared because they are adjacent to each other with similar 

east-west orientations and similar climatic conditions. A 

comparison of corresponding BFI values (fig. 12) indicates 

that small differences exist between the two stations. 

Corresponding BFI values for the Double Mountain Fork gage 

are larger than BFI values for the Salt Fork gage 52 percent 

of the time during the study period (fig. 12A). BFI values for 

each station plotted in relation to each other (fig. 12B) indicate 

that neither station is substantially different from the other 

with about the same distribution on either side of the equal 

BFI line. About water year 2000, the Double Mountain Fork 

appears to gain in base flow while base flow in the Salt Fork 

remains constant (figs. 12A and 12B).

Clear Fork Brazos River Basin

BFIs were calculated using data from two streamflowgaging stations in the Clear Fork Brazos River Basin, USGS 

streamflow-gaging station 08084000 Clear Fork Brazos River 

at Nugent, Tex., (hereinafter the Clear Fork Nugent gage, site 

CF–6) and USGS streamflow-gaging station 08085500 Clear 

Fork Brazos River at Fort Griffin, Tex., (hereinafter the Clear 

Fork Fort Griffin gage, site CF–12) (fig. 6; table 2). The Clear 

Fork Nugent gage and Clear Fork Fort Griffin gage are 93.2 

river miles apart. The BFI for the Clear Fork Nugent gage 

ranged from 0.02 in 2000 to 0.79 in 1998, and the median BFI 

was 0.28 (fig. 13). The BFI at the Clear Fork Fort Griffin gage 

ranged from 0.02 in 1978 to 0.55 in 1983 with a median BFI 

of 0.23 (fig. 14). The plot of the BFI values for both sites by 

year (fig. 15A) shows the BFIs for Clear Fork Nugent were 

greater than for Clear Fork Fort Griffin about 50 percent of 

the time. When the BFI for Clear Fork Fort Griffin is greater 

than that for Clear Fork Nugent, the difference is generally 

small (less than 0.08 (fig. 15B). The Clear Fork Nugent gage 

(site CF–6) is relatively near the areal extents of the Seymour, 

Edwards-Trinity (Plateau), and Blaine aquifers in the Clear 

Fork Basin and the stream at site CF–7 probably receives 

larger amounts of base flow from these aquifers compared to 

the stream at the Clear Fork Fort Griffin gage (site CF–12); the 

reach between the Clear Fork Nugent gage and the Clear Fork 

Fort Griffin gage is not close to any major or minor aquifers.

North Bosque River Basin

USGS streamflow-gaging station 08095000 North 

Bosque River near Clifton, Tex., (hereinafter North Bosque 

Clifton gage, site NB–7) is 42 mi upstream from the mouth 

of the North Bosque River near Waco (fig. 16). The cities of 

Meridian, Stephenville, and Clifton discharge treated effluent 

into the river upstream from this station (fig. 7). 

The annual BFI for the North Bosque Clifton gage 

ranged from 0.07 in 1986 to 0.57 in 1978 with a median BFI 

of 0.30 (fig. 16). The northern part of the North Bosque River 

drainage basin overlies the Trinity aquifer (fig. 2). The median 

BFI at the North Bosque Clifton gage, while not as large as 

the median BFI of 0.35 at USGS streamflow-gaging station 

08091500 Paluxy River at Glen Rose, Tex. (hereinafter the 

Paluxy gage), is larger than median BFIs determined for all 

of the other long-term streamflow records evaluated in this 

study. This finding indicates that a substantial amount of the 

total flow in the North Bosque River Basin might come from 

groundwater, treated effluent from the Meridian, Stephenville, 

and Clifton wastewater-treatment plants, or a combination of 

groundwater and treated effluent. The North Bosque River is 

impounded by Waco Lake; regulated releases from Waco Lake 

provide flow to the main stem of the Brazos River north of 

Waco (fig. 1).
22 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni low f- esa B

Date

08082000 Salt Fork Brazos River near Aspermont, TexasMedian

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

index low f- esa B

Date

08080500 Double Mountain Fork Brazos River near Aspermont, TexasMedian

Figure 10. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08082000 Salt Fork Brazos River near Aspermont, Texas, 1966–2009.Figure 11. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08080500 Double Mountain Fork Brazos River near Aspermont, Texas, 1966–2009.
Base Flow 23

A

B

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedniwofl-esaB

Date

0

0.80.70.60.50.40.30.20.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

08082500 Double Mountain Fork Brazos River near Aspermont, Texas08082000 Salt Fork Brazos River near Aspermont, Texas

Equal Base Flow Index Line

Base-flow index for 08080500 Double Mountain Fork Brazos

River near Aspermont, Texas

Base-flow index for 08082000 Salt Fork 

Brazos River near Aspermont, Texas

Figure 12. A, Time series of annual base-flow index and B, Relation between annual base-flow index for U.S. Geological Survey streamflow-gaging stations 08080500 Double Mountain Fork Brazos River near Aspermont, Texas, and 08082000 Salt Fork Brazos River near Aspermont, Tex., 1966–2009.
24 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08084000 Clear Fork of the Brazos River at Nugent, TexasMedian

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08085500 Clear Fork of the Brazos River at Fort Griffin, TexasMedian

Figure 13. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08084000 Clear Fork Brazos River at Nugent, Texas, 1966–2009.Figure 14. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08085500 Clear Fork Brazos River at Fort Griffin, Texas, 1966–2009.
Base Flow 25

A

B

0

0.800.700.600.500.400.300.200.10

1966 1976 1986 1996 2006

xedni w olf-esaB

Date

0

0.80.70.60.50.40.30.20.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

08084000 Clear Fork of the Brazos River at Nugent, Texas08088550 Clear Fork of the Brazos River at Fort Griffin, Texas

Equal Base Flow Index Line

Base-flow index for 08084000 Clear Fork of the Brazos

River at Nugent, Texas

Base-flow index for 08085500 Clear Fork of the 

Brazos River at Fort Griffin, Texas

Figure 15. A, Time series of annual base-flow index and B, Relation between annual base-flow index for U.S. Geological Survey streamflow-gaging station 08084000 Clear Fork Brazos River near Nugent, Texas and U.S. Geological Survey streamflow-gaging station 08085500 Clear Fork Brazos River at Fort Griffin, Tex., 1966–2009.
26 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08095000 North Bosque River near Clifton, TexasMedian

Figure 16. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08095000 North Bosque River near Clifton, Texas, 1966–2009. 
Base Flow 27

Brazos River Basin (main stem)

Long-term streamflow records were analyzed for six 

USGS streamflow-gaging stations in the Brazos River Basin 

(main stem) (table 1; fig. 8):

• 08082500 Brazos River at Seymour, Tex. 

(hereinafter the Brazos Seymour gage, site BMS–2) 

• 08088000 Brazos River near South Bend, Tex. 

(hereinafter Brazos South Bend gage, site BMS–3) 

• 08089000 Brazos River near Palo Pinto, Tex. 

(hereinafter Brazos Palo Pinto gage, site BMS–5) 

• 08090800 Brazos River near Dennis, Tex. 

(hereinafter Brazos Dennis gage, site BMS–6)

• 08091000 Brazos River near Glen Rose, Tex. 

(hereinafter Brazos Glen Rose gage, site BMS–7)

• 08091500 Paluxy River at Glen Rose, Tex., 

(hereinafter Paluxy gage, site BMST–8)

The Paluxy gage (site BMST–8) is on a major tributary to 

main stem of the Brazos River (fig. 8, table 2). There are other 

sites in the upper Brazos River Basin present with sufficient 

data for long-term analysis, however, they were not chosen 

for analysis because of various reasons such as unstable rating 

curves or instrument problems. 

The Brazos Seymour gage (site BMS–2) and Brazos 

South Bend gage (site BMS–3) are 89.2 river miles apart on 

the main stem of the Brazos River in the upper reaches of the 

drainage basin (table 2; fig. 8). The Brazos Seymour gage 

is 847.4 river miles upstream from the mouth of the Brazos 

River, and is the farthest upstream site where BFI values were 

determined. The BFI values at The Brazos Seymour gage 

(fig. 17) ranged from 0.04 in 1974 to 0.47 in 2009 with the 

median BFI of 0.22 for the period of record. The BFI values 

at the Brazos South Bend gage ranged from 0.03 in 1978 to 

0.56 in 1993 with the median BFI of 0.24 for the period of 

record used (1966–2009) (fig. 18). An analysis of the plot 

of the BFI values for these two stations by year (fig. 19A) 

indicates that for the same year, the BFI at the Brazos South 

Bend gage was larger than the BFI at the Brazos Seymour 

gage 74 percent of the time (BFI values mostly plot to the 

left of the equal BFI line) (fig. 19B), a pattern that indicates 

base flow composes a larger amount of total streamflow at the 

Brazos South Bend gage than at the Brazos Seymour gage. 

The Brazos South Bend gage is downstream from a part of the 

main-stem basin that overlies the Seymour aquifer (fig. 2). 

Possum Kingdom Lake, formed by Morris Sheppard 

Dam at river mile 687.5 upstream from the mouth of the 

Brazos River, is the farthest upstream major reservoir on the 

main stem of the Brazos River, and impounds the Brazos 

River between the Brazos South Bend gage (site BMS–3) and 

the Brazos Palo Pinto gage (site BMS–5) (fig. 8). Constructed 

in 1941, the conservation pool storage of Possum Kingdom 

Lake is 556,220 acre-ft (U.S. Geological Survey, 2001). Water 

stored in Possum Kingdom Lake is used for power generation, 

irrigation, municipal, industrial, and recreational purposes, 

and releases from Possum Kingdom Lake for these purposes 

contribute to the base flow of the Brazos River upstream 

from Lake Granbury. BFI values were computed for the two 

long-term USGS streamflow-gaging stations on this reach of 

the river, the Brazos Palo Pinto gage (fig. 20), and the Brazos 

Dennis gage (fig. 21).

The Brazos Palo Pinto gage (site BMS–5) is at river mile 

667.3 upstream from the mouth, 20.0 mi downstream from 

Possum Kingdom Lake outflows. The Brazos Dennis gage 

(site BMS–6) is at river mile 589.8; 77.5 river miles separate 

the two gages (U.S. Geological Survey, 2001) (fig. 8). The 

annual BFI for the Brazos Palo Pinto gage (fig. 20) ranged 

from 0.04 in 1978 to 0.61 in 2009 with a median BFI of 0.19. 

The annual BFI for the Brazos Dennis gage (fig. 21) ranged 

from 0.06 in 1978 to 0.50 in 2009 with a median BFI of 0.27, 

indicating base flow composed a larger percentage of the total 

flow at the Brazos Dennis gage than at the Brazos Palo Pinto 

gage. About 90 percent of the time, the BFI at the Brazos 

Dennis gage is greater compared to the BFI at the Brazos Palo 

Pinto gage (fig. 22A) and plots to the left of the equal BFI 

line on fig. 22B. There does not appear to be an appreciable 

contribution to flow from aquifers in the drainage basin to the 

main stem of the Brazos River between the Brazos Palo Pinto 

gage and the Brazos Dennis gage (site BMS–6) (figs. 2 and 3). 

Because streamflow data collection at the Brazos Dennis gage 

began in May 1968, annual base-flow index data from the two 

gages could not be compared for 1966 through 1968. 

Downstream from the Brazos Dennis gage (site BMS–6) 

is a reach of the Brazos River (extending from Lake 

Granbury at river mile 542.5; U.S. Geological Survey, 2009) 

downstream to Lake Whitney (formed by Whitney Dam at 

river mile 442.4; U.S. Geological Survey, 2009) (fig. 8). 

The annual base-flow indexes for two long-term USGS 

streamflow-gaging stations used to measure flows in this 

reach—one on the main stem of the Brazos River, the Brazos 

Glen Rose gage (site BMS–7; fig. 8, table 2) and one on 

tributary to the main stem, the Paluxy gage (site BMST–8 

fig. 8, table 2)—are shown in figures 23 and 24, respectively.

The Paluxy River, which enters the Brazos River 

downstream from the Brazos Glen Rose gage, contributes to 

the base flow in this reach of the Brazos River. BFI values at 

the Brazos Glen Rose gage ranged from 0.04 in 1984 to 

0.37 in 1972, with a median BFI of 0.19 (fig. 23). BFI values 

at the Paluxy gage were higher than those at the Brazos Glen 

Rose gage, ranging from 0.11 in 1989 to 0.75 in 1983 with 

a median BFI of 0.35 (fig. 24), indicating a larger amount 

of the streamflow at the Paluxy gage consisted of base flow 

compared to streamflow at the Brazos Glen Rose gage. 
28 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esaB

Date

08082500 Brazos River at Seymour, TexasMedian

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08088000 Brazos River near South Bend, TexasMedian

Figure 17. Annual base-flow index at U.S. Geological Survey streamflow-gaging station 08082500 Brazos River at Seymour, Texas, 1967–2009.Figure 18. Annual base-flow index at U.S. Geological Survey streamflow-gaging station 08088000 Brazos River near South Bend, Texas, 1966–2009.
Base Flow 29

A

B

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf-esaB

Date

0

0.80.70.60.50.40.30.20.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

08082500 Brazos River at Seymour, Texas08088000 Brazos River near South Bend, Texas

Equal Base Flow Index Line

Base-flow index for 08082500 Brazos River at Seymour, Texas

Base-flow index for 08088000 Brazos River 

near South Bend, Texas

Figure 19. A, Time series of annual base-flow index and B, Relation between annual base-flow index for U.S. Geological Survey streamflow-gaging station 08082500 Brazos River at Seymour, Texas, and U.S. Geological Survey streamflow-gaging station 0808800 Brazos River near South Bend, Tex., 1967–2009.
30 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08089000 Brazos River near Palo Pinto, TexasMedian

0

0.800.700.600.500.400.300.200.10

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08090800 Brazos River near Dennis, TexasMedian

Figure 20. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08089000 Brazos River near Palo Pinto, Texas, 1966–2009.

Figure 21. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08090800 Brazos River near Dennis, Texas, 1969–2009.
Base Flow 31

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf-esaB

Date

0

0.80.70.60.50.40.30.20.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

A

B

08089000 Brazos River near Palo Pinto, Texas08090800 Brazos River near Dennis, Texas

Equal Base Flow Index Line

Base-flow index for 08089000 Brazos River near 

Palo Pinto, Texas

Base-flow index for 08090800 Brazos River near 

Dennis, Texas

Figure 22. A, Time series of annual base-flow index and B, Relation between annual base-flow index for U.S. Geological Survey streamflow-gaging station 08089000 Brazos River near Palo Pinto, Texas, 1966–2009, and U.S. Geological Survey streamflow-gaging station 08090800 Brazos River near Dennis, Tex., 1969–2009.
32 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

xedni w olf- esa B

Date

08091000 Brazos River near Glen Rose, TexasMedian

0

0.80.70.60.50.40.30.20.1

1966 1976 1986 1996 2006

ase-flow index B

Date

08091500 Paluxy River at Glen Rose, TexasMedian

Figure 23. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08091000 Brazos River near Glen Rose, Texas, 1966–2009.Figure 24. Annual base-flow index for U.S. Geological Survey streamflow-gaging station 08091500 Paluxy River at Glen Rose, Texas, 1966–2009.
Streamflow Gain and Loss Assessment 33

Mann-Kendall trend analysis is a nonparametric test 

used for non-normally distributed data to analyze the changes 

in the median over time (Helsel and Hirsch, 2002). The 

Mann-Kendall trend analysis test was performed on annual 

BFI values (one value per year for the study period) for each 

long-term streamflow-gaging station, and a p-value of less 

than or equal to 0.05 (p < 0.05) was used to assign statistical 

significance to temporal trends in the BFI values. Upward 

(increasing) trends in BFI values were found at three USGS 

streamflow-gaging stations: the Double Mountain Fork 

Aspermont gage (p<0.01), the Brazos River Palo Pinto gage 

(p<0.01), and the Brazos River Dennis gage at each gage 

(p<0.01). Lake Alan Henry is upstream from the Double 

Mountain Fork Aspermont gage. Possum Kingdom Lake is 

upstream from the Brazos River Palo Pinto and Brazos River 

Dennis gages and Lake Granbury is downstream from the 

Brazos River Palo Pinto and Brazos River Dennis gages. 

As stated in the Hydrograph Separation and Trend Analysis 

section, judgment is needed to determine if upward trends in 

flow over time are caused by changes in reservoir releases or 

by increases in base flow. Flows at the Double Mountain Fork 

Aspermont, Brazos River Palo Pinto, and Brazos River Dennis 

gages are all regulated by reservoir releases, and additional 

analyses are needed before these streamflow trends can be 

characterized as indicative of changes in base flow over time. 

For example, releases from Lake Alan Henry, which was 

impounded in October 1993 (U.S. Geological Survey, 2001), 

might be increasing flow in the Double Mountain Fork at 

certain times of the year, giving the perception of increasing 

base flow in this stream.

Streamflow Gain and Loss Assessment

Streamflow gain and loss amounts were determined for 

each of the five subbasins of the upper Brazos River Basin 

(figs. 4-8). Streamflow gain and loss amounts were determined 

during the June and October surveys (June 6–9, 2010, and 

October 16–19, 2010) when no substantial rainfall (more than 

0.10 in.) occurred and base-flow conditions were stable.

Salt Fork Brazos River Basin

Streamflow in the Salt Fork Brazos River Basin (fig. 4) 

was measured at eight sites during June 6–9, 2010, and nine 

sites during October 16–19, 2010. The USGS station names 

and corresponding site identifiers where streamflow was 

measured in the Salt Fork River Basin in June and October 

2010 are as follows:

• 341643102013700 Running Water Draw at Farm Road 

2884 near Edmonson, Tex. (site SF–1; fig. 4, table 2)

• 08080700 Running Water Draw at Plainview, Tex. 

(site SF–2; fig. 4, table 2)

• 335939101293500 Running Water Draw at Farm 

Road 784 at Sandhill, Tex. (site SF–3; fig. 4, table 2)

• 08080900 White River below falls near Crosbyton, Tex. 

(site SF–4; fig. 4, table 2)

• 332426101030700 White River at Ranch Road 261 near 

Spur, Tex. (site SF–5; fig. 4, table 2)

• 08080940 Salt Fork Brazos River at State Highway 208 

near Clairemont, Tex. (site SF–6; fig. 4, table 2)

• 331608100420100 Duck Creek at Farm Road 2320 near 

Jayton, Tex. (site SF–7; fig. 4, table 2)

• 08082000 Salt Fork Aspermont gage (site SF–9; 

fig. 4 table 2)

In June 2010, no flow was observed at sites SF–1 through 

SF–3 or at site SF–5, and scant flow (0.06 ft3/s) was measured at 

site SF–4.At site SF–6, flow of 1.06 ft3/s was measured; this site 

is downstream from the White River Reservoir. The replicate 

streamflow measurement at site SF–6 was 0.85 ft3/s. Flows of 

1.56 ft3/s were added to the main stem of the Salt Fork Brazos 

River from Duck Creek (as measured at site SF–7). Upstream 

from the confluence of the Salt Fork and Double Mountain 

Fork, 9.41 ft3/s was measured on the Salt Fork at site SF–9. The 

specific-conductance value for the flow measured at SF–9 was 

53,000 microsiemens per centimeter at 25 degrees Celsius (μS/

cm), the largest specific-conductance value measured at any site 

during the study. The Salt Fork watershed is underlain by the 

Seymour and Ogallala major aquifers (fig. 2) and by 

the Edwards-Trinity (High Plains), Dockum, and Blaine 

minor aquifers (fig. 3).

Streamflow was measured during October 16–19, 2010, 

at the same eight sites on the Salt Fork Brazos River Basin 

measured during June 6–9, 2010, and one new site (USGS 

streamflow-gaging station 08081100 Croton Creek below Short 

Creek near Jayton, Tex. [site SF-8; fig. 4, table 2]). As in the 

June survey, no flow was again measured at the three farthest 

upstream sites, SF–1 through SF–3, and less than 0.10 ft3/s was 

measured at site SF–4 upstream from White River Reservoir 

and at site SF–5 downstream from White River Reservoir. 

The specific-conductance value at site SF–4 was 1,060 μS/cm 

compared to 2,640 μS/cm at site SF–5. Streamflow of 2.86 ft3/s 

and specific conductance of 22,940 μS/cm were measured at 

site SF–6 (upstream from the confluence of the Salt Fork with 

Duck Creek). On Duck Creek at site SF–7, streamflow of 1.75 

ft3/s and specific conductance of 3,630 μS/cm were measured. 

Streamflow at site SF–9 on the Salt Fork upstream from its 

confluence with Double Mountain Fork was 10.9 ft3/s (the 

replicate measurement 

was 11.5 ft3/s), and specific conductance was measured as 

48,670 μS/cm. Small amounts of inflows with relatively 

high specific-conductance values (more than 20,000 μS/cm) 

occurred in the reach downstream from sites SF–7 and SF–8. 

The streamflow at site SF–8 was 0.10 ft3/s and the specific 
34 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

conductance was 35,600 μS/cm. Croton Creek is a tributary to 

the reach of the Salt Fork between sites SF–6 and SF–9. From 

the data collected in the June and October surveys, a gaining 

reach in the Salt Fork Brazos River Basin began upstream 

from where Duck Creek flows into the Salt Fork Brazos 

River at site SF–6 and continued downstream past site SF–9 

to the outlet of the basin. The Dockum, Blaine, and Seymour 

aquifers underlie the basin between sites SF–6 and SF–9 

(figs. 2 and 3) and might contribute to the additional base 

flow measured downstream from site SF–6 to site SF–9.

Double Mountain Fork Brazos River Basin

Streamflow in the Double Mountain Fork Brazos River 

Basin was measured at eight sites during June 6–9, 2010, and

again during October 16-19, 2010. The USGS station names 

and corresponding site identifiers where streamflow was 

measured in the Double Mountain Fork Brazos River Basin 

are as follows:

• 335325101593700 Blackwater Draw at Farm Road 179 

near Abernathy, Tex. (site DMF-1; fig. 5, table 2)

• 334137102005900 Yellow House Draw at Farm Road 

1294 at Shallowater, Tex. (site DMF–2; fig. 5, table 2)

• 333047101393300 North Fork Double Mountain Fork 

Brazos River at Farm Road 400 near Lubbock, Tex. 

(site DMF–3; fig. 5, table 2)

• 331909101232900 North Fork Double Mountain 

Fork Brazos River at Farm Road 207 near Post, Tex. 

(site DMF–4; fig. 5, table 2)

• 08079600 Double Mountain Fork Brazos River at 

Justiceburg, Tex. (site DMF-5, fig. 5, table 2)

• 08080000 Double Mountain Fork Brazos River near 

Rotan, Tex. (site DMF-6, fig. 5, table 2)

• 08080500 Double Mountain Fork Aspermont gage 

(site DMF-7, fig. 5, table 2)

• 331116099573600 Double Mountain Fork Brazos 

River at Highway 380 near Rule, Tex. (site DMF-8, 

fig. 5, table 2)

The two sites west of Lubbock (DMF–1 and 2) had no 

measurable streamflow during the June survey; these are 

the two farthest upstream sites on the North Fork Double 

Mountain Fork. Consecutive streamflow measurements on 

June 7, 2010, at site DMF–3, on the North Fork Double 

Mountain Fork Brazos River (hereinafter North Fork Double 

Mountain Fork) measured the flow as 2.83 ft3/s (upstream 

from Farm Road 400) and 6.90 ft3/s (downstream from Farm 

Road 400). The City of Lubbock discharges groundwater to 

the North Fork Double Mountain Fork for municipal 

purposes upstream from site DMF–3; these discharges from 

the City of Lubbock’s well field (fig. 5) were consistently 

3.1 ft3/s in the reach downstream from the City of Lubbock 

wastewater-treatment plant and upstream from Farm Road 400 

(Aubrey A. Spear, Lubbock Director of Water Resources, oral 

commun., January 24, 2011), and account for the measured 

streamflow of 2.83 ft3/s on June 7 upstream from Farm 

Road 400 because the stream is normally dry upstream from 

these municipal discharges. Discharges of treated effluent 

from the Lubbock wastewater-treatment plant occur at Farm 

Road 400 (fig. 5), and range from 0 to 14 ft3/s; as much as 

10.8 ft3/s of this effluent might be diverted before being 

discharged at Farm Road 400 for use in a nearby powerplant 

(Aubrey A. Spear, Lubbock Director of Water Resources, oral 

commun., January 24, 2011). Discharges of treated effluent 

at site DMF–3 account for the additional 4.17 ft3/s measured 

downstream from Farm Road 400 at site DMF–3 on June 7, 

2010. Streamflow measured at site DMF–4 north of Post, Tex., 

was 2.78 ft3/s, indicating a losing reach between sites DMF–3 

and DMF–4. During the June survey, no flow was measured 

at site DMF–5, near Justiceburg, on the South Fork Double 

Mountain Fork Brazos River (South Fork). The flow during 

the June survey at site DMF–6 was 36.8 ft3/s. Site DMF–6 is 

on the Double Mountain Fork near Rotan, downstream from 

the confluence of the North and South Forks of the Double 

Mountain Fork, and downstream from the mapped areal 

extent of the Dockum aquifer (fig. 3). The flow at site 

DMF–6 represents a substantial gain compared to the 

2.78 ft3/s measured at the closest upstream site, DMF–4. 

Flow continued to increase downstream from site DMF–6; 

the flow at site DMF–7 was 43.3 ft3/s (replicate measurement 

was 41.8 ft3/s). Specific-conductance values of 5,690 and 

5,670 μS/cm were measured at sites DMF–6 and DMF–7, 

respectively, representing a large increase compared to the 

2,000 μS/cm measured at upstream site DMF–3, possibly 

because of contributions of relatively saline groundwater to 

the base flow at sites DMF–6 and DMF–7. Although measured 

flow increased at least 5 ft3/s from the 36.8 ft3/s at site DMF–6 

to the 41.8 and 43.3 ft3/s measured at site DMF–7, specificconductance values were essentially the same at sites DMF–6 

and DMF–7, indicating the same likely source of water to the 

stream as the one accounting for the increase in streamflow 

between sites DMF–4 and DMF–6. Measured flow increased 

approximately 10 ft3/s during the June survey between site 

DMF–7 and site DMF–8 near Rule, Tex., upstream from the 

confluence of the Double Mountain Fork and the Salt Fork; 

specific-conductance values decreased from 5,670 μS/cm to 

4,400 μS/cm, indicating additional base flow consisting of 

somewhat less saline water was added to the Double Mountain 

Fork between sites DMF–7 and DMF–8. 

The eight sites in the Double Mountain Fork Basin 

measured during June 6–9, 2010, were measured again during 

October 16-19, 2010 (table 2). No-flow conditions were 

once again observed at the two farthest upstream sites on the 

North Fork Double Mountain Fork west of Lubbock, sites 

DMF–1 and 2. Streamflow entering site DMF–3 was 2.28 ft3/s 
Streamflow Gain and Loss Assessment 35

and leaving site DMF–3 was 7.86 ft3/s with a mean specific 

conductance of 2,030 μS/cm. Streamflow on the North Fork 

Double Mountain Fork at site DMF–4 was 3.17 ft3/s, with a 

specific conductance of 1,110 μS/cm, corroborating the 

losing reach observed between sites DMF–3 and DMF–4 

during the June survey. A gaining reach in the North Fork 

Double Mountain Fork from site DMF–4 near Post, Tex., 

downstream to site DMF–8 near the outlet of the basin 

was identified from the June and October survey results. A 

small amount of streamflow, 0.20 ft3/s, was measured at site 

DMF–5 during the October survey on the South Fork Double 

Mountain Fork upstream from its confluence with the North 

Fork Double Mountain Fork (specific conductance of 

14,190 μS/cm), indicating the increase in streamflow from 

the 3.17 ft3/s measured at site DMF–4 to the 22.8 ft3/s 

measured at site DMF–6 (with a replicate measurement 

of 23.5 ft3/s) might consist of inputs from the Dockum 

aquifer, which underlies part of this reach. Specific 

conductance at site DMF–6 during the October survey was 

7,950 μS/cm. Streamflow continued to increase downstream 

from site DMF–6 to site DMF–7 (27.3 ft3/s) and site DMF–8 

(36.5 ft3/s). Specific conductance remained in a range from 

7,000 to 8,000 μS/cm at sites DMF–7 and DMF–8. Similar 

to the June survey results, these results indicate that the 

increase in base flow observed beginning at site DMF–6 

downstream through site DMF–8 might originate from the 

same source, possibly the Blaine aquifer which underlies this 

reach. In addition to the Blaine aquifer, the Double Mountain 

Fork watershed also is underlain by the Seymour, Ogallala, 

Edwards-Trinity (High Plains), and Dockum aquifers 

(figs. 2–3), and combinations of waters from these aquifers 

might contribute to the gains in streamflow observed in the 

June and October surveys in the Double Mountain Fork Basin.

Clear Fork Brazos River Basin

Nineteen sites (CF–1–19) were measured in the Clear 

Fork Brazos River Basin (fig. 6) during June 6–9, 2010 

(table 2). The USGS station names and corresponding site 

identifiers where streamflow was measured in the Clear Fork 

Brazos River Basin are as follows:

• 08083100 Clear Fork Brazos River near Roby, Tex. 

(site CF-1, fig. 6, table 2)

• 323720100071200 Sweetwater Creek at Farm Road 

1812 near Noodle, Tex. (site CF-2, fig. 6, table 2)

• 08083230 Clear Fork Brazos River near Noodle, Tex. 

(CF-3, fig. 6, table 2)

• 323635099495800 Clear Fork Brazos River at County 

Road 509 at Hawley, Tex. (site CF-4, fig. 6, table 2)

• 08083245 Mulberry Creek near Hawley, Tex. 

(site CF-5, fig. 6, table 2)

• 08084000 Clear Fork Brazos River at Nugent, Tex. 

(site CF-6, fig. 6, table 2)

• 08084100 Deadman Creek near Nugent, Tex. 

(site CF-7, fig. 6, table 2)

• 324701099362000 Clear Fork Brazos River at 

Highway 6 at Lueders, Tex. (site CF-8, fig. 6, table 2)

• 325732099273200 Clear Fork Brazos River near 

Lueders, Tex. (site CF-9, fig. 6, table 2)

• 08084800 California Creek near Stamford, Tex. 

(site CF-10, fig. 6, table 2)

• 330433099333300 Paint Creek below Lake Stamford 

near Haskell, Tex. (site CF-11, fig. 6, table 2)

• 08085500 Clear Fork Brazos River at Fort Griffin, Tex. 

(site CF-12, fig. 6, table 2)

• 322606099230400 Hubbard Creek at Highway 283 

near Baird, Tex. (site CF-13, fig. 6, table 2)

• 08086100 Hubbard Creek near Albany, Tex. 

(site CF-14, fig. 6, table 2)

• 322424098591200 Sandy Creek at Highway 6 at 

Cisco, Tex. (site CF-15, fig. 6, table 2)

• 08086300 Big Sandy Creek near Breckenridge, Tex. 

(site CF-16, fig. 6, table 2)

• 325310098543200 Hubbard Creek at Farm Road 578 

at Crystal Falls, Tex. (site CF-17, fig. 6, table 2

• 324812098535800 Gonzales Creek near Breckenridge, 

Tex. (site CF-18, fig. 6, table 2)

• 325406098535700 Clear Fork Brazos River at 

Farm Road 578 at Crystal Falls, Tex. (site CF-19, 

fig. 6, table 2)

During the June survey, streamflow at the westernmost 

and farthest upstream site in the Clear Fork Basin, site 

CF–1, was 0.77 ft3/s, and the specific conductance was 

11,200 μS/cm. Streamflow in Sweetwater Creek at Farm 

Road 1812 near Noodle (site CF–2), just upstream from 

the confluence of Sweetwater Creek and Clear Fork, was 

0.85 ft3/s and the specific conductance was 5,000 μS/cm. 

Streamflow of 5.15 ft3/s was measured at site CF–3 (specific 

conductance at site CF–3 was 9,030 μS/cm, an intermediate 

value compared to the larger and smaller specific-conductance 

values measured at sites CF–1 and CF–2, respectively). 

During the June survey, streamflow increased between sites 

CF–1 and CF–3; groundwater inflows from the Seymour 

aquifer or other groundwater sources might account for this 

gain in streamflow (fig. 3). No gain in streamflow was realized 

between sites CF–3 (5.15 ft3/s) and CF–4 (4.39 ft3/s), and there 

were no measureable inflows to the Clear Fork from Mulberry 
36 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Creek (as measured at site CF–5). Streamflow at site CF–6, 

Clear Fork Brazos at Nugent (composed of streamflow from 

site CF–5 and releases from Lake Fort Phantom Hill) was 

5.64 ft3/s, representing a small gain of 1.25 ft3/s compared to 

streamflow at upstream site CF–4. Streamflow measured at 

site CF–7 on Deadman Creek was 19.8 ft3/s, with a specific 

conductance of 1,630 μS/cm. Streamflow in Deadman Creek 

consists primarily of treated effluent from the City of Abilene; 

during the June survey, average daily releases ranged from a 

minimum of 10.5 ft3/s on June 7 to a maximum of 17.2 ft3/s 

on June 8 (Mickey Chaney, Wastewater Superintendent, 

City of Abilene, written commun., February 22, 2011). 

Despite receiving flow of 5.64 ft3/s from site CF–6 and 19.8 

ft3/s from site CF–7, flow at site CF–8 was the same as the 

flow at site CF–7 (19.8 ft3/s), indicating losing reaches from 

site CF–8 to these upstream sites (fig. 6). The reach of the 

Clear Fork Brazos River Basin from sites CF–4 through 

CF–8 is probably more affected by discharges of treated 

effluent from Abilene, Tex., and less by contributions from 

the Seymour aquifer (fig. 2). 

Sites CF–10 on California Creek, a tributary to Paint 

Creek, and CF–11, Paint Creek downstream from Lake 

Stamford, measure the flows that combine to form Clear 

Fork Brazos River upstream from site CF–9. Streamflow 

at site CF–10 was 3.61 ft3/s, and streamflow at site CF–11, 

downstream from Lake Stamford, was 5.15 ft3/s. Streamflow 

at site CF–9 was 20.3 ft3/s with a specific conductance of 

2,120 μS/cm, which similar to the streamflow and specificconductance measured at CF–8, except specific conductance 

at site CF–8 was 710 μS/cm higher compared to site CF–9. 

Streamflow measured at site CF–12 was 26.1 ft3/s, reflecting 

inflows from Paint Creek (8.76 ft3/s, which is the combined 

flow from sites CF-10, 3.61 ft3/s, and CF-11, 5.15 ft3/s) and 

Clear Fork Brazos River at site CF–9 (20.3 ft3/s); comparing 

the combined flows measured at sites CF–11 and CF–9 with 

the flow measured at site CF–12, there was not any substantial 

increase or decrease in the flow of the Clear Fork Brazos River 

from groundwater inputs. The reach of the Clear Fork Brazos 

River between CF-8 to the confluence with the Brazos River 

near South Bend does not overlie any of the major or minor 

aquifers (figs. 2 and 3). Specific conductance at site CF–12 

was 2,300 μS/cm. There were no substantial measured inflows 

to Clear Fork Brazos River between sites CF–12 (26.1 ft3/s, 

2,300 μS/cm) and CF–19 (26.3 ft3/s, 1,980 μS/cm), which is 

upstream from the confluence of Clear Fork Brazos River 

with Hubbard Creek.

The Hubbard Creek drainage basin makes up the eastern 

third of the Clear Fork Brazos River drainage, joining the 

Clear Fork Brazos River north of Breckenridge, Tex., and sites 

CF–13 through CF–18 are within its boundaries. Sites CF–13 

and CF–14, on Hubbard Creek upstream from Hubbard Creek 

Reservoir, had no flow. Sites CF–15 and CF–16, on Sandy 

Creek and Big Sandy Creek, respectively, had less than 1 ft3/s. 

Site CF–18, which sometimes carries treated effluent from the 

City of Breckenridge, and site CF–17, just upstream from the 

confluence of Hubbard Creek with Clear Fork Brazos River, 

had no flow, indicating streamflow in Clear Fork Brazos River 

upstream from its confluence with the main stem of the Brazos 

River are mostly from the western part of the drainage basin.

The same 19 sites measured in the Clear Fork Brazos 

River Basin (fig. 6) during June 2010 (sites CF–1 through 

CF–19) (table 2) were measured again in October 2010. 

Similar patterns in streamflow amounts were observed, with 

generally larger amounts of streamflow measured during the 

October survey compared to the June survey. From the June 

and October surveys, a gaining reach was identified in the 

Clear Fork Brazos River from near Roby, Tex., downstream to 

near Noodle, Tex. (flows of 0.77 and 1.04 ft3/s were measured 

at site CF–1 in the June and October surveys, respectively, and 

flows of 5.15 and 6.75 ft3/s were measured at site CF–3 in the 

June and October surveys, respectively). Between sites CF–3 

and CF–4, an increase of 4.05 ft3/s was measured 

during October 2010 (about a 60 percent increase in flow) 

compared to a decrease of 0.76 ft3/s during the June survey 

for the same stream reach (about a 15 percent decrease in 

flow). Upstream from site CF–7, streamflow in Deadman 

Creek was composed of treated effluent from the City of 

Abilene ranging from 11.1 ft3/s to 13.0 ft3/s during October 

16–19, 2010 (Mickey Chaney, Wastewater Superintendent, 

City of Abilene, written commun., Feb. 22, 2011). A second 

gaining reach was observed in the Clear Fork Brazos River 

from Hawley, Tex., downstream to Nugent, Tex. As during 

the June survey, larger flows were measured at downstream 

site CF–6 compared to upstream site CF–4 (flows of 4.39 and 

10.8 ft3/s were measured at site CF–4 in June and October 

respectively, and flows of 5.64 and 14.6 ft3/s were measured 

at site CF–6 in the June and October surveys, respectively). 

In the October survey, a larger amount of streamflow was 

measured at site CF–8 compared to site CF–6, but the 

combined flows from sites CF–6 (14.6 ft3/s) and CF–7 

(14.1 ft3/s) of 28.7 ft3/s in the October survey were slightly 

more than the streamflow measured at site CF–8 (26.5 ft3/s)—

indicating that the stream reaches between sites CF–6 and 

CF–8 and between sites CF–7 and CF–8 were losing reaches. 

At site CF–9, 27.1 ft3/s was measured in the October survey, 

compared to 20.3 ft3/s measured at this site in the June survey. 

At site CF–19, the farthest downstream site in the basin, 

29.9 ft3/s was measured during the October synoptic 

measurements (a replicate measurement of 31.3 ft3/s was 

within 5 percent), compared to 26.3 ft3/s measured during the 

June survey. Specific-conductance values measured during 

June at site CF–9 were essentially the same as those measured 

during October (2,120 μS/cm in June, and 2,160 μS/cm in 

October) and were much higher at site CF–19 in June 

(1,980 μS/cm) compared to October (653 μS/cm).

North Bosque River Basin 

Ten sites (NB–1–10) were measured in the North Bosque 

River Basin (fig. 7) during June 6–9, 2010 (table 2). The 

USGS station names and corresponding site identifiers where 

streamflow was measured in the North Bosque River Basin are 

as follows:
Streamflow Gain and Loss Assessment 37

• 321513098133100 North Fork North Bosque River at 

State Route 108 near Stephenville, Tex. (site NB-1, 

fig. 7, table 2)

• 08094800 North Bosque River at Hico, Tex. 

(site NB–2, fig. 7, table 2)

• 315839097534200 North Bosque River at Highway 6 

near Iredell, Tex. (site NB-3, fig. 7, table 2

• 320106097465700 East Bosque River at Farm 

Road 927 near Walnut Springs, Tex. (site NB–4, 

fig. 7, table 2)

• 315510097394300 North Bosque River at Highway 22 

at Meridian, Tex. (site NB–5, fig. 7, table 2)

• 314842097364100 Meridian Creek at Highway 6 near 

Clifton, Tex. (site NB–6, fig. 7, table 2)

• 08095000 North Bosque River near Clifton, Tex. 

(site NB-7, fig. 7, table 2)

• 314136097320700 Neils Creek at Highway 6 near 

Valley Mills, Tex. (site NB-8, fig. 7, table 2)

• 08095200 North Bosque River at Valley Mills, Tex. 

(site NB-9, fig. 7, table 2)

• 313830097220100 North Bosque River near China 

Springs, Tex. (site NB-10, fig. 7, table 2)

No flow was measured during the June survey at the 

most upstream site on the North Fork North Bosque River, site 

NB–1, north of Stephenville, Tex. Streamflow at site NB–2, 

just upstream from Hico, Tex., was 11.7 ft3/s and the specific 

conductance was 414 μS/cm. The basin from site NB–1 to 

site NB–2 overlies the Trinity aquifer (fig. 2), which might 

be a source of some of the base flow to this reach; treated 

effluent from Stephenville also is added to the North Bosque 

River upstream from site NB–2. The Stephenville wastewatertreatment plant has a capacity of 3 million gallons per day 

(4.64 ft3/s) but typically processes 1.5 million gallons per 

day (2.32 ft3/s) (City of Stephenville, 2009). The streamflow 

at site NB–3, North Bosque River near Iredell, Tex., was 

14.2 ft3/s and the specific conductance was 292 μS/cm. 

Streamflow increased to 26.1 ft3/s at the next site downstream 

on the main stem of North Bosque River, site NB–5 (specific 

conductance was not measured at site NB–5 during the June 

survey). At site NB–4 on the East Bosque River, the largest 

tributary to the North Bosque River in the reach between 

Iredell and Meridian, measured streamflow was less than 

1 ft3/s, indicating groundwater from the underlying Trinity 

aquifer and not inflow from East Bosque River was likely 

the main source of streamflow to the main channel of the 

North Bosque River. Gains in streamflow in the downstream 

direction on the main channel to NB–5 were probably from a 

combination of groundwater sources and a small amount of 

treated effluent (less than 0.70 ft3/s) from Meridian, Tex. (City 

of Meridian, 2010). Streamflow at site NB–7 on the main stem 

of the North Bosque was 47.9 ft3/s. Flow at site NB–7includes 

the 10.3 ft3/s (8.37 ft3/s replicate measurement) of tributary 

inflow from Meridian Creek (measured at site NB–6) and 

treated effluent from the Clifton wastewater-treatment plant. 

The Clifton wastewater-treatment plant has a capacity of 

650,000 gallons per day (1.01 ft3/s) but typically processes 

about 261,000 gallons per day (0.40 ft3/s); batches of treated 

effluent are released about every 2 hours when holding tanks 

reach capacity (Robin Harvey, Public Works Director, City 

of Clifton, written commun., December 6, 2011). An inflow 

of 18.2 ft3/s was measured at site NB–8 on the tributary 

Neils Creek, which, when added to the 47.9 ft3/s measured 

at site NB–7, yields 66.1 ft3/s —an amount that is almost 

20 ft3/s less than the measured streamflow at downstream 

site NB–9 at Valley Mills (86.7 ft3/s). Downstream from site 

NB–9, streamflow increased from 86.7 to 103 ft3/s at site 

NB–10 (107 ft3/s replicate measurement), upstream from any 

possible backwater from Waco Lake. The difference between 

the combined flows from sites NB–7 and NB–8 compared 

to the flow at site NB–9, and the increase in flow from site 

NB–9 to NB–10 indicate a gaining reach, and the gains in 

streamflow are likely caused by groundwater inflows. Specificconductance values decreased slightly from 514 μS/cm at site 

NB–9 to 464 μS/cm at site NB–10. 

The same 10 sites measured in the North Bosque River 

Basin in June 2010 were measured in October 2010 (NB–1 

through NB–10) (table 2). Streamflow amounts generally were 

much less during the October survey but still followed the 

patterns observed in the June survey. As in June, no flow was 

observed at site NB–1 in October. Streamflow at site NB–2 

during October was 4.16 ft3/s, compared to 11.7 ft3/s during 

June. Streamflow at site NB–7 (near Clifton) during October 

was 17.6 ft3/s compared to 47.9 ft3/s in June. Streamflow at 

site NB–10 was 41.4 ft3/s in October compared to 103 ft3/s 

in June. Flow in the tributaries to the North Bosque showed 

similar patterns of more flow in June compared to October 

at sites on the main stem, with streamflow at site NB–8 

on Neils Creek decreasing from 18.2 ft3/s (June survey) to 

6.84 ft3/s (October survey). Although the downstream gains 

were smaller in October compared to June, the pattern of 

increasing flow in the downstream direction was similar in 

each survey. Specific-conductance values measured at sites 

NB–2 and NB–3 increased by about 100 μS/cm at each site 

in October compared to June, possibly because dissolved 

solids were more concentrated in the smaller streamflow 

amounts measured in October compared to June. However, 

specific-conductance values in the lower North Bosque reach 

(measured at sites NB–6 through NB–10) did not differ 

appreciably between the June and October surveys, with 

specific-conductance values generally in the 400–550 μS/cm 

range during both June and October. Specific conductance for 

North Bosque River Basin ranged from 292–522 μS/cm for 

June and 429–539 μS/cm for October, indicating there was 

likely no change in the source of the additional streamflow. 

Based on the June and October survey results, most of the 

North Bosque River was characterized as gaining streamflow, 

beginning with no flow north of Stephenville, Tex., increasing 
38 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

downstream to more than 100 ft3/s and 41.4 ft3/s near China 

Springs, Tex., in the June and October surveys, respectively 

(flow during the June survey at site NB–10 was 103 ft3/s 

[replicate measurement was 107 ft3/s ] and the flow at site 

NB–10 was 41.4 ft3/s during the October survey).

Brazos River Basin (main stem)

Streamflow in Brazos River Basin from west of Knox 

City, Tex., to north of Waco (fig. 8) was measured at 8 sites on 

the main stem of the Brazos River and 14 sites on tributaries 

to the main stem of the Brazos River. The USGS station names 

and corresponding site identifiers where streamflow was 

measured in the Brazos River Basin are as follows:

• 332533099544100 Brazos River at Highway 143/222 

near Knox City, Tex. (site BMS-1; fig. 8, table 2)

• 08082500 Brazos River at Seymour, Tex. 

(site BMS-2; fig. 8, table 2)

• 08088000 Brazos River near South Bend, Tex. 

(site BMS-3; fig. 8, table 2)

• 08088610 Brazos River near Graford, Tex. 

(site BMS-4; fig. 8, table 2)

• 08089000 Brazos River near Palo Pinto, Tex. 

(site BMS-5; fig. 8, table 2

• 08090800 Brazos River near Dennis, Tex. 

(site BMS-6; fig. 8, table 2)

• 08091000 Brazos River near Glen Rose, Tex. 

(site BMS-7; fig. 8, table 2)

• 08093100 Brazos River near Aquilla, Tex. 

(site BMS-8; fig. 8, table 2)

• 333323099263000 Lake Creek at Farm Road 2070 

near Seymour, Tex. (site BMST-1; fig. 8, table 2)

• 332744099144300 Millers Creek at Highway 183/283 

near Seymour, Tex. (site BMST-2; fig. 8, table 2)

• 08088100 Salt Creek at Olney, Tex. (site BMST-3; 

fig. 8, table 2)

• 331140098390300 Salt Creek at Highway 380 near 

Newcastle, Tex. (site BMST-4; fig. 8, table 2)

• 323932098072300 Palo Pinto Creek at Farm Road 129 

near New Salem, Tex. (site BMST-5; fig. 8, table 2)

• 324456098025900 Rock Creek at Farm Road 3028 

near Sturdivant, Tex. (site BMST-6; fig. 8, table 2)

• 324151097581900 Grindstone Creek at I-20 near 

Brock Junction, Tex. (site BMST-7; fig. 8, table 2)

• 08091500 Paluxy River at Glen Rose, Tex. 

(site BMST-8; fig. 8, table 2)

• 08091750 Squaw Creek near Glen Rose, Tex. 

(site BMST-9; fig. 8, table 2)

• 08092000 Nolan River at Blum, Tex. 

(site BMST-10; fig. 8, table 2)

• 314220097174100 Childress Creek at Farm Road 2490 

near Waco, Tex. (site BMST-11; fig. 8, table 2)

• 08093360 Aquilla Creek above Aquilla, Tex. 

(site BMST-12; fig. 8, table 2)

• 315300097114200 Cobb Creek near Aquilla, Tex. 

(site BMST-13; fig. 8, table 2)

• 08093560 Aquilla Creek at Farm Road 1858 near 

Ross, Tex. (site BMST-14; fig. 8, table 2)

With the exception of site BMST–1, streamflow was 

measured at all of the main-stem Brazos River Basin sites 

in June and October 2010. Streamflow was measured during 

the October survey at site BMST–1 but not during the June 

survey. Specific conductance was measured at all main-stem 

Brazos River Basin sites with measurable flow in June and 

October with the following exceptions: sites BMS–6 and 

BMS–7 (October only), BMST–1 (October only), BMST–2 

(no measurements), BMST–6 through BMST-10 (October 

only), BMST-12 (October only), and BMST- 13 

(no measurements).

Because of the number of reservoirs in this part of the 

Brazos River Basin, flow in individual reaches of the Brazos 

River separated by Possum Kingdom Lake, Lake Granbury, 

and Lake Whitney is described. Streamflow in the reach from 

the confluence of the Salt and Double Mountain Forks to 

upstream from Possum Kingdom Lake, including streamflow 

from the Clear Fork Brazos River, which enters the Brazos 

River near South Bend, was quantified from data collected 

at sites BMS–1 through BMS–3 and sites BMST–1 through 

BMST–4. Streamflow at site BMS–1 in the June survey was 

86.2 ft3/s; this site is downstream from the confluence of the 

Salt Fork and the Double Mountain Fork. The flow at site 

BMS–1 during the June survey was 39 percent larger than the 

combined flows measured at sites SF–9 and DMF–8 during 

the same survey (61.91 ft3/s). This increase in streamflow 

might be from groundwater inflows from the Seymour (fig. 2) 

and Blaine (fig. 3) aquifers. Streamflow continued to increase 

between sites BMS–1 (near Knox City, Tex.) and BMS–2 

(at Seymour, Tex.); flow of 142 ft3/s was measured at 

site BMS–2. Millers Creek provided no tributary inflow 

to the Brazos River (there was no flow at site BMST–2). 

Specific-conductance values measured at sites BMS–1 and 

BMS–2 (15,070 and 16,630 μS/cm, respectively) were 

fairly consistent, indicating there was likely no change in 

the source of the additional streamflow, just an increase in 
Streamflow Gain and Loss Assessment 39

quantity. Streamflow at site BMS–3 was 163 ft3/s; this site is 

upstream from Possum Kingdom Lake and downstream from 

the confluence of the Clear Fork and the main stem Brazos 

River. The flow at site BMS–3 was 3 percent smaller than 

the combined flows measured at sites BMS–2 and CF–19, 

indicating that an appreciable loss or gain of streamflow 

did not occur between sites BMS–2 and BMS–3. Specific 

conductance of the streamflow at site BMS–3 was 8,940 μS/

cm, a large decrease from site BMS–2 reflecting the addition 

of water with lower specific conductance at site CF–19 on the 

Clear Fork (1,980 μS/cm) to the streamflow in the main stem. 

Sites BMST–3 and BMST–4 are on Salt Creek, upstream 

from Lake Graham (fig. 8). Flows of 0.06 and 12.8 ft3/s 

were measured at sites BMST–3 and BMST–4, respectively, 

indicating a gaining reach. Streamflow from Salt Creek is 

usually stored in Lake Graham; releases downstream to the 

Brazos River from Lake Graham only occur during rare 

periods of abundant runoff. Downstream from Lake Graham, 

some of the flow in Salt Creek is treated effluent from 

Graham, Tex., which operates a wastewater-treatment plant 

that is permitted to treat as much as 3.2 ft3/s (City of Graham, 

2011). Flow in Salt Creek downstream from Lake Graham to 

Possum Kingdom Lake was not measured.

Analysis of data collected during the October gain-loss 

measurements showed similar results although at lower levels 

of streamflow. Streamflow was 61.9 ft3/s during the October 

survey at site BMS–1, which was 28 percent less than the 

streamflow of 86.2 ft3/s measured at this site in June. From 

site BMS–1, streamflow during the October survey increased 

in the downstream direction to 93.7 ft3/s at site BMS–2 and 

to 127 ft3/s at site BMS–3. Streamflows during the October 

survey at site BMS–2 (142 ft3/s) and site BMS–3 (163 ft3/s) 

were 34 and 22 percent less, respectively, compared to the 

streamflows measured at these sites during the June survey. 

In the October survey, specific-conductance values measured 

at the three main-stem sites (BMS–1, BMS-2, and BMS–3), 

were 17,550, 14,680, and 8,600 μS/cm, respectively, and 

follow the same pattern of generally decreasing in the 

downstream direction observed during the June survey. 

Groundwater inflows (possibly from the underlying Seymour 

aquifer) likely cause specific conductance to generally 

decrease in the downstream direction in the reach from site 

BMS–1 to BMS–3. 

Streamflow in the second reach of the main stem, Brazos 

River from Possum Kingdom Reservoir to Lake Granbury, 

was characterized by using data collected at the following 

sites: BMS–4, which measures releases from Possum 

Kingdom Dam, BMS–5, which is upstream from Palo Pinto 

Creek, and BMS–6, which is downstream from Palo Pinto 

Creek and upstream from Lake Granbury (fig. 8). All three 

of these sites are continuous streamflow-gaging stations 

operated by the USGS. Inflows to the Brazos River from Palo 

Pinto Creek are measured at site BMST–5, and flow past this 

site consists mostly of releases from Lake Palo Pinto. Data 

collected at measurement sites on tributaries, sites BMST–5 

through BMST-7, also were used for this reach. During the 

June survey, the streamflow was 105 ft3/s at site BMS–4 

and the specific conductance was 2,510 μS/cm; water was 

being released from Possum Kingdom Dam at the time this 

measurement was made. The specific conductance at site 

BMS–4 of 2,510 μS/cm was markedly lower compared to 

the specific conductance of 8,940 μS/cm measured during 

the same set of synoptic measurements at site BMS–3 

upstream from Possum Kingdom Lake, indicating that water 

being released from Possum Kingdom Dam was of different 

quality compared to inflow to Possum Kingdom Lake during 

this time, as measured at site BMS–3. The reason for this 

difference might be that the reservoir has impounded large 

amounts of storm runoff over time with much lower levels of 

specific conductance compared to the specific conductance 

measured in typical base flow. Streamflow measured at 

BMS–5 during the June survey was 138 ft3/s (verified with 

a replicate measurement of 132 ft3/s), indicating an increase 

of 33 ft3/s or 31 percent from flows also measured in June 

at site BMS–4. Gage height is continuously recorded at this 

site and varied less than 0.1 ft throughout the June survey. 

There was scant variation in specific conductance from site 

BMS–4 to site BMS–5 in June 2010 (2,510 and 2,410 μS/

cm, respectively), indicating the same quality water, likely 

from the same source, was flowing past both sites. Specificconductance values for site BMS–6 were not measured. 

Tributary inflows measured at sites BMST–5, BMST–6, and 

BMST–7 totaled 6.89 ft3/s, amounts that were much less than 

the 54 ft3/s increase in flow measured in June 2010 at site 

BMS–6 compared to the flow at site BMS–5 (192 ft3/s were 

measured at site BMS–6 in June 2010). The gage height 

record at site BMS–6 showed a continual decrease of about 

0.10 ft/d during June 6–9, 2010, indicating that flow in the 

reach was still receding from a May 29, 2010, storm 

(Texas State Climatologist, 2010). Evaluating the reach 

between sites BMS–5 and BMS–6 as a gaining reach on the 

basis of the June survey might be erroneous because of the 

ongoing runoff in this reach from the May 2010 storm 

(Texas State Climatologist, 2010).

The October 2010 survey was done during a period 

when mean daily gage height at the three study sites 

(BMS-4 through BMS-6) was nearly constant, varying less 

than 0.05 ft among the sites for all of the days in the survey. 

Streamflow being released from Possum Kingdom Dam 

(measured at site BMS–4) was 156 ft3/s and increased to 

164 ft3/s at site BMS–5 and then to 172 ft3/s at site BMS–6. 

No substantial streamflow from tributaries was identified 

between sites BMS–4 and BMS–5. Tributary inflow between 

sites BMS–5 and BMS–6 totaled 3.36 ft3/s from the following 

sites: BMST–5 on Palo Pinto Creek, 2.20 ft3/s (replicate 

measurement 3.19 ft3/s), BMST–6 on Rock Creek, 1.10 ft3/s, 

and BMST–7 on Grindstone Creek, 0.06 ft3/s. Streamflow 

at site BMS–6 was 172 ft3/s, only 4.64 ft3/s greater than the 

combined streamflow measured at site BMS–5 plus inflows 

from the tributaries, well within a measurement error of 
40 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

8 percent (Turnipseed and Sauer, 2010); therefore, this reach 

does not appear to be gaining or losing if more emphasis 

is given to the streamflow measurements made during the 

October survey than to streamflow measurements made 

during the June survey. The reach from site BMS–4 through 

site BMS–6 does not overlie any major (fig. 2) or minor 

(fig. 3) aquifers. Specific-conductance values measured at the 

main-stem study sites ranged from 2,970 μS/cm at site 

BMS–6 to 3,080 μS/cm at site BMS–4 during the October 

survey. Specific-conductance values were not measured 

during the June survey at sites BMS–6 or BMS–7.

Streamflow in the Brazos River reach between Lake 

Granbury and Lake Whitney (fig. 8) was characterized from 

data collected at site BMS–7 near Glen Rose, Tex., and sites 

on tributaries on the Paluxy River at Glen Rose (BMST–8), 

Squaw Creek near Glen Rose (BMST–9), and Nolan River 

at Blum (BMST–10). Base flows in this reach are dominated 

by tributary inflows from the Paluxy River and Squaw Creek. 

Much of the flow in Squaw Creek consists of regulated 

releases from Squaw Creek Lake, which is sustained in part 

by diversions from Lake Granbury. The Nolan River, which 

flows directly into Lake Whitney, is another noteworthy 

tributary to this part of the basin. Streamflow measured during 

then June survey at site BMS–7 was 99 ft3/s, and tributary 

inflows to the Brazos main stem downstream from site 

BMS–7 from Paluxy River and Squaw Creek totaled 51.0 ft3/s. 

In June, streamflow at site BMST–10 on the Nolan River was 

6.63 ft3/s. No specific-conductance values were obtained for 

sites BMST–8 through BMST-10 during the June synoptic 

measurements. Streamflow measured in October at mainstem site BMS–7 was 62.4 ft3

/s, with tributary flow from the 

Paluxy River and Squaw Creek contributing 14.29 ft3/s. The 

streamflow measured at site BMST–10 on the Nolan River 

in October was 8.76 ft3/s, and the specific conductance was 

812 μS/cm. Specific conductance in October at site BMS–7 

was 2,260 μS/cm, a reduction of 710 μS/cm compared to 

the specific-conductance value of 2,970 μS/cm measured 

during October at site BMS–6, further indicating that releases 

from reservoirs can appreciably affect water quality in the 

upper Brazos River Basin. This reach of the main stem of the 

Brazos River could not be characterized as gaining or losing 

because there was only one measurement site on the Brazos 

River in this reach. Flow in the main stem increased from 

tributary inflows from the Paluxy River and Squaw Creek, 

and the Brazos might receive groundwater inflows from the 

Trinity aquifer in this reach as well. Additional measurements 

(upstream and downstream sites on this reach) are necessary 

to confirm if this reach is a gaining reach.

The Brazos River reach between Lake Whitney and the 

mouth of the North Bosque River north of Waco contained 

one main-stem measurement site near the outflow from Lake 

Whitney, BMS–8. Tributary inflow was measured at sites 

BMST–12 and 14 on Aquilla Creek and site BMST–13 Cobb 

Creek which enters Aquilla Creek between sites BMST–12 

and 14 and at site BMST–11 on Childress Creek. By 

coincidence, flows of 252 ft3/s were measured at site BMS–8 

during the June and October surveys (flow at site BMS–8 

typically varies from 200 to 2,000 ft3/s most days because of 

large changes in the amount of water released from the dam 

impounding Lake Whitney [U.S. Geological Survey, 2009]). 

Substantial increases in streamflow were measured in June 

from site BMST–12 (outlet of Aquilla Lake) of 2.26 ft3/s to 

site BMST–14 of 15.5 ft3/s with no additional streamflow 

added from Cobb Creek (BMST–13, no flow). Childress 

Creek (site BMST–11) added 3.54 ft3/s to the main stem. 

Streamflow measured in October in Aquilla Creek followed 

similar patterns, with 14 ft3/s (BMST–12) being released 

from Aquilla Lake and Childress Creek (site BMST–11) 

contributing 4.33 ft3/s (replicate measurement of 5.02 ft3/s). 

The Woodbine aquifer underlies part of the Aquilla Creek 

Basin. The reach of the main stem of the Brazos River from 

Lake Whitney to Waco increased in flow from tributary 

inflows and groundwater inputs. This reach of the main stem 

of the Brazos River could not be characterized as gaining 

or losing because there was only one measurement site on 

the Brazos River in this reach. Additional measurements 

(upstream and downstream sites on this reach) are necessary 

to confirm if this reach is a gaining reach.

Based on the results of the June and October surveys, 

streamflow gains were identified in the reach of the main 

stem of the Brazos River from where the Brazos River main 

stem forms at the confluence of the Salt Fork Brazos River and 

Double Mountain Fork Brazos River near Knox City, Tex., 

downstream to near Seymour, Tex. Increases in flow were 

observed in the main stem downstream from Lake Granbury 

to Lake Whitney, and downstream from Lake Whitney to 

the confluence of the Brazos River and Childress Creek, 

but because there was only one main-stem measurement 

site in each of these reaches, there was insufficient data to 

characterize these reaches as gaining reaches. Flow in the 

Brazos River increased from 86.2 ft3/s near Knox City to 

142 ft3/s near Seymour during the June survey, and from 

61.9 ft3/s to 93.7 ft3/s during the October survey. The flows 

near Knox City and Seymour were measured at USGS 

stations 332533099544100 Brazos River at Highway 143/222 

near Knox City, Tex. (site BMS–1), and 08082500 Brazos 

River near Seymour, Tex. (site BMS–2), respectively. Flow 

was measured at one site on the main stem of the Brazos 

River in the Lake Granbury to Lake Whitney reach, at 

USGS streamflow-gaging station 08091000 Brazos River 

near Glen Rose, Tex. (site BMS–7). Substantial tributary 

flows to the Brazos River from the Paluxy River, Nolan River, 

and Squaw Creek increased flow in this reach. Inflows of 

35.4 ft3/s (June) and 9.84 ft3/s (October) were measured at 

USGS streamflow-gaging station 08091500 Paluxy River at 

Glen Rose, Tex. (site BMST–8). Inflows from Nolan River 

of 6.63 ft3/s (June) and 8.76 ft3/s (October) were measured at 

USGS streamflow-gaging station 08092000 Nolan River at 

Blum, Tex. (site BMST–10), which flows directly into Lake 

Whitney. Inflows of 15.6 ft3/s (June) and 4.45 ft3/s (October) 

from Squaw Creek to the Brazos River were measured at 

USGS streamflow-gaging station 08091750 Squaw Creek 
Summary 41

near Glen Rose, Tex. (site BMST–9). The inflows from the 

Paluxy River, Nolan River, and Squaw Creek are downstream 

from the 99 ft3/s (June) and 62.4 ft3/s (October) measured at 

site BMS–7. Downstream from site BMS–7, flow in the main 

stem increased to 252 ft3/s at USGS streamflow-gaging station 

08093100 Brazos River near Aquilla, Tex. (site BMS–8), 

during both the June and October surveys. 

Contributions of Streamflow to the Main 

Channels of Each of the Five Subbasins 

Contributions of streamflow to the main channels of each 

of the five subbasins during the June survey ranged from less 

than 15 ft3/s in the Salt Fork Brazos River Basin to more than 

100 ft3/s for the North Bosque Brazos River Basin (fig. 25). 

While an overall increase in streamflow was measured from 

the headwaters of the Clear Fork Brazos River Basin to the 

outlet, a large part of 26.3 to 29.9 ft3/s measured at the most 

downstream site in the basin was likely treated effluent from 

the Abilene, Tex., wastewater-treatment plant. Releases from 

the three main-stem reservoirs in the upper Brazos River 

Basin—Possum Kingdom Lake, Lake Granbury, and Lake 

Whitney—dominated the quantity of flows in the Brazos 

main-stem reach downstream from Possum Kingdom Lake. 

Contributions of streamflow to the main channels of 

each designated basin (fig. 26) measured in the October 

survey were less than those measured in June, and varied 

from less than 12 ft3/s for the Salt Fork Brazos River Basin to 

41.4 ft3/s for the North Bosque River Basin. BFI values for the 

Double Mountain Fork near Aspermont gage (site DMF–7) 

indicated an upward trend from 1966–2009 in the baseflow component of the total streamflow amount. BFI values 

for the Brazos River near Palo Pinto (site BMS–5) and the 

Brazos River near Dennis (site BMS–6) indicated statistically 

significant upward trends in the base-flow components for 

these two sites located in the stream reach between Possum 

Kingdom Lake and Lake Granbury, indicating that releases 

from Possum Kingdom Lake and Lake Palo Pinto Reservoir 

are comprising an increasingly large part of flows in this part 

of the main stem of the Brazos River.

Summary 

During 2010–11, the U.S. Geological Survey (USGS), 

in cooperation with the Texas Water Development Board, 

used hydrograph separation to quantify historical base flow 

at 11 USGS streamflow-gaging stations between water years 

1966–2009 and used two sets of synoptic measurements 

of streamflow and specific conductance (the first in June 

2010, followed by another set in October 2010) to quantify 

streamflow gains and losses in the upper Brazos River Basin 

from the New Mexico–Texas State line to Waco, Texas. This 

study complements previous work that quantified base flows in 

part of the lower Brazos River Basin downstream from Waco 

to near Freeport, Tex., using base-flow analysis and 

synoptic streamflow measurements. The following subbasins 

compose the study area: Salt Fork Brazos River Basin, 

Double Mountain Fork Brazos River Basin, Clear Fork Brazos 

River Basin, North Bosque River Basin, and the Brazos 

River Basin (main stem) (including its tributaries). Several 

underlying major and minor aquifers are in the upper Brazos 

River Basin that are hydraulically connected to the Brazos 

River might add streamflow in the upper Brazos River Basin. 

Major aquifers are the Seymour, Ogallala, Edwards-Trinity 

(Plateau), and Trinity, and minor aquifers are the Brazos 

River Alluvium, Woodbine, Edwards-Trinity (High Plains), 

Dockum, and Blaine. 

Base-flow analysis was done using historical streamflow 

data from 11 USGS streamflow-gaging stations in the upper 

Brazos River Basin (5 on the main stem of the Brazos River 

and 6 on tributaries to the Brazos River) to compute yearly 

base-flow indexes (base flow divided by total streamflow) for 

each station. The base-flow index was used to indicate the 

fraction of flow consisting of base flow on an annual basis 

for the period of record evaluated at each streamflow-gaging 

station. At nine stations there were long-term streamflow 

data from water years 1966–2009 (October 1965 through 

September 2009); at two stations slightly shorter periods 

of record (water years 1967–2009 and 1969–2009) were 

available. Hydrograph separation was done to calculate 

base-flow indexes for each year of streamflow record using 

the USGS computer program Hydrograph Separation and 

Analysis. The median base-flow indexes were 0.16 and 0.15 

at USGS streamflow-gaging stations 08082000 Salt Fork 

Brazos River near Aspermont, Tex., and 08080500 Double 

Mountain Fork Brazos River near Aspermont, Tex., 

respectively. At USGS streamflow-gaging stations 08084000 

Clear Fork Brazos River at Nugent, Tex., and 08085500 

Clear Fork Brazos River at Fort Griffin, Tex., the median 

baseflow-indexes were 0.28 and 0.23, respectively, indicating 

the amount of streamflow consisting of base flow was larger 

in the Clear Fork Brazos River Basin compared to the Salt 

Fork Brazos River Basin or Double Mountain Fork Brazos 

River Basin.

 The largest median base-flow index for any station was 

0.35 at USGS streamflow-gaging station 08091500 Paluxy 

River at Glen Rose, Tex. The second largest base-flow index 

was 0.30 at USGS streamflow-gaging station 08095000 

North Bosque River near Clifton, Tex. Median base-flow 

indexes on the main stem of the Brazos River upstream from 

Possum Kingdom Lake were 0.22 at USGS streamflow-gaging 

station 08082500 Brazos River at Seymour, Tex., and 0.24 at 

USGS streamflow-gaging station 08088000 Brazos River at 

South Bend, Tex. The base-flow indexes for stations between 

Possum Kingdom Lake and Lake Granbury were 0.19 and 

0.27 at USGS streamflow-gaging stations 08089000 Brazos 

River near Palo Pinto, Tex., and 08090800 Brazos River 

near Dennis, Tex., respectively. A median base-flow index of 

0.19 was also measured at USGS streamflow-gaging station 

08091000 Brazos River near Glen Rose, Tex., located between 
42 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

0

50

100

150

200

250

300

1,200 1,100 1,000 900 800 700 600 500 400

EXPLANATION

River Basin

Possum

Kingdom Lake

Lake

Granbury

Lake

Whitney

Salt Fork

Double Mountain Fork

Clear Fork

North Bosque River

Brazos Main stem

Distance upstream from mouth of Brazos River, in miles

Streamflow, in cubic feet per second

0

50

100

150

200

250

300

1,200 1,100 1,000 900 800 700 600 500 400

EXPLANATION

River Basin

Possum

Kingdom Lake

Lake

Granbury

Lake

Whitney

Salt Fork

Double Mountain Fork

Clear Fork

North Bosque River

Brazos Main stem

Distance upstream from mouth of Brazos River, in miles

Streamflow, in cubic feet per second

Figure 25. Instantaneous streamflow measured during June 2010 at U.S. Geological Survey streamflow-gaging stations in the five 

subbasins of the upper Brazos River Basin, Texas (Salt Fork Brazos River, Double Mountain Fork Brazos River, Clear Fork Brazos River, 

North Bosque River, and the main stem of Brazos River and its tributaries). 

Figure 26. Instantaneous streamflow measured during October 2010 at U.S. Geological Survey streamflow-gaging stations in the five 

subbasins of the upper Brazos River Basin, Texas (Salt Fork Brazos River, Double Mountain Fork Brazos River, Clear Fork Brazos River, 

North Bosque River, and the main stem of Brazos River and its tributaries).
Summary 43

Lake Granbury and Lake Whitney. A Mann-Kendall trend 

analysis test was performed on annual base-flow index 

values (one value per year for the study period) for each of 

the 11 streamflow records that were analyzed, and a p-value 

of 0.05 used to assign statistical significance for the 

occurrence of a trend in the base-flow index data set for 

each historical period of record analyzed. Upward trends in 

base-flow index values indicating increasing flows during 

the study period were found for USGS streamflow-gaging 

stations 08080500 Double Mountain Fork Brazos River near 

Aspermont, Tex., 08089000 Brazos River near Palo Pinto, 

Tex., and 08090800 Brazos River near Dennis, Tex. Flows 

at these three streamflow-gaging stations are regulated by 

reservoir releases, and additional analyses are needed before 

these streamflow trends can be characterized as indicative of 

changes in base flow over time. 

Streamflow gains and losses were characterized in each 

of the five subbasins composing the upper Brazos River 

Basin using data from two synoptic measurements (surveys) 

of streamflow and specific conductance in 2010. Data were 

collected from 66 sites during June 6–9, 2010 (June survey) 

and from 68 sites during October 16–19, 2010 (October 

survey). Gaining reaches were characterized in the Salt Fork 

Brazos River Basin and Double Mountain Fork Brazos River 

Basin during both surveys. The gaining reach in the Salt Fork 

Brazos River Basin began at USGS streamflow-gaging station 

08080940 Salt Fork Brazos River at State Highway 208 near 

Clairemont, Tex. (site SF–6), upstream from where Duck 

Creek flows into the Salt Fork Brazos River and continued 

downstream past USGS streamflow-gaging station 08082000 

Salt Fork Brazos River near Aspermont, Tex. (site SF–9), to 

the outlet of the basin. The streamflows of 1.06 and 2.86 ft3/s 

were measured in the June and October surveys, respectively, 

at site SF–6. At downstream site SF–9, streamflows of 9.41 

and 10.9 ft3/s were measured during the June and October 

surveys, respectively. In the Double Mountain Fork Brazos 

River Basin, a gaining reach from near Post, Tex., downstream 

to the outlet of the basin was identified. Flow increased 

from about 3 ft3/s during the June (2.78 ft3/s) and October 

(3.17 ft3/s) surveys at USGS station 331909101232900 North 

Fork Double Mountain Fork Brazos River at Farm Road 

207 near Post, Tex. (site DMF–4), to about 36–53 ft3/s near 

the outlet of the Double Mountain Fork Brazos River Basin 

during the June (36.5 ft3/s) and October (52.5 ft3/s) surveys 

at USGS station 331116099573600 Double Mountain Fork 

Brazos River at Highway 380 near Rule, Tex. (site DMF–8). 

A gaining reach was identified in the Clear Fork Brazos River 

from near Roby, Tex., downstream to near Noodle, Tex. (flows 

of 0.77 and 1.04 ft3/s were measured at USGS streamflowgaging 08083100 Clear Fork Brazos River near Roby, Tex. 

[site CF–1], in the June and October surveys, respectively, 

and flows of 5.15 and 6.75 ft3/s were measured at USGS 

streamflow-gaging 08083230 Clear Fork Brazos River near 

Noodle, Tex. [site CF–3], in the June and October surveys, 

respectively). A second gaining reach was observed in the 

Clear Fork Brazos River from Hawley, Tex., downstream to 

Nugent, Tex. (flows of 4.39 and 10.8 ft3/s were measured at 

USGS station 323635099495800 Clear Fork Brazos River at 

County Road 509 at Hawley, Tex. [site CF–4], in June and 

October respectively, and flows of 5.64 and 14.6 ft3/s were 

measured at USGS streamflow-gaging 08084000 Clear Fork 

Brazos River at Nugent, Tex. [site CF–6], in the June and 

October surveys, respectively). Most of the North Bosque 

River was characterized as gaining streamflow, beginning 

with no flow north of Stephenville, Tex., increasing 

downstream to more than 100 ft3/s and 41.4 ft3/s near 

China Springs, Tex., in the June and October surveys, 

respectively (flow during the June survey at USGS station 

313830097220100 North Bosque River near China Springs, 

Tex. [site NB–10], was 103 ft3/s [replicate measurement was 

107 ft3/s] and the flow at site NB–10 was 41.4 ft3/s during 

the October survey). 

Based on the results of the June and October surveys, 

streamflow gains were identified in the reach of the main stem 

of the Brazos River from where the Brazos River main stem 

forms at the confluence of the Salt Fork Brazos River and 

Double Mountain Fork Brazos River near Knox City, Tex., 

downstream to near Seymour, Tex. Increases in flow were 

observed in the main stem downstream from Lake Granbury 

to Lake Whitney, and downstream from Lake Whitney to 

the confluence of the Brazos River and Childress Creek, 

but because there was only one main-stem measurement 

site in each of these reaches, there was insufficient data to 

characterize these reaches as gaining reaches. Flow in the 

Brazos River increased from 86.2 ft3/s near Knox City to 

142 ft3/s near Seymour during the June survey, and from 

61.9 ft3/s to 93.7 ft3/s during the October survey. The flows 

near Knox City and Seymour were measured at USGS 

stations 332533099544100 Brazos River at Highway 

143/222 near Knox City, Tex. (site BMS–1), and 08082500 

Brazos River near Seymour, Tex. (site BMS–2), respectively. 

Flow was measured at one site on the main stem of the 

Brazos River in the Lake Granbury to Lake Whitney reach, 

at USGS streamflow-gaging station 08091000 Brazos River 

near Glen Rose, Tex. (site BMS–7). Substantial tributary 

flows to the Brazos River from the Paluxy River, Nolan River, 

and Squaw Creek increased flow in this reach. Inflows of 

35.4 ft3/s (June) and 9.84 ft3/s (October) were measured at 

USGS streamflow-gaging station 08091500 Paluxy River at 

Glen Rose, Tex. (site BMST–8). Inflows from Nolan River 

of 6.63 ft3/s (June) and 8.76 ft3/s (October) were measured at 

USGS streamflow-gaging station 08092000 Nolan River at 

Blum, Tex. (site BMST–10), which flows directly into Lake 

Whitney. Inflows of 15.6 ft3/s (June) and 4.45 ft3/s (October) 

from Squaw Creek to the Brazos River were measured at 

USGS streamflow-gaging station 08091750 Squaw Creek 

near Glen Rose, Tex. (site BMST–9). The inflows from the 

Paluxy River, Nolan River, and Squaw Creek are downstream 

from the 99 ft3/s (June) and 62.4 ft3/s (October) measured at 

site BMS–7. Downstream from site BMS–7, flow in the main 

stem increased to 252 ft3/s at USGS streamflow-gaging station 

08093100 Brazos River near Aquilla, Tex. (site BMS–8), 

during both the June and October surveys. 
44 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

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Texas Water Development Board, 2007a, TWDB Mapping 

Website—Major aquifers, minor aquifers: accessed 

September 6, 2007, at http://www.twdb.state.tx.us/

mapping/. 

Texas Water Development Board, 2007b, Trinity aquifer: 

accessed April 4, 2011, at http://www.twdb.state.tx.us/

GwRD/GMA/PDF/TrinityAquifer.pdf.

Texas Water Development Board, 2010, Texas Water 

Development Board Home Page: Texas Water 

Development Board, accessed July 19, 2010, at 

http://www.twdb.state.tx.us/.

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Volume 23, Number 5, 6, 9, 10, accessed April 4, 2011, at 

http://atmo.tamu.edu/osc/tx/OctBull10.pdf.

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.

Turco, M.J., East, J.W., and Milburn, M.S., 2007, Base flow 

(1966–2005) and streamflow gain and loss (2006) of the 

Brazos River, McLennan County to Fort Bend County, 

Texas: U.S. Geological Survey Scientific Investigations 

Report 2007–5286, 27 p.

U.S. Census Bureau, 2011, United States census 2010: 

accessed September 13, 2011, at http://2010.census.

gov/2010census/data/.

U.S. Geological Survey, 2001, Water resources data, Texas, 

water year 2000—Volume 3: U.S. Geological Survey WaterData Report TX-00-3, 490 p.
References 45

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, accessed March 10, 

2011, at http://pubs.water.usgs.gov/twri9A.

U.S. Geological Survey, 2009, National Water Information 

System: accessed in May 2009 at http://waterdata.usgs.gov/

tx/nwis/.

Wahl, K.L., and Wahl, T.L, 1995, Determining the flow 

of Comal Springs at New Braunfels, Texas, in Texas 

Water ‘95, San Antonio, Texas, August 16-17, 1995, 

Proceedings: American Society of Civil Engineers, Texas 

Section, p. 77–86.
46 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Appendix 1. Hydrographic Separation Results

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]

Water year

USGS station 08082000 Salt Fork 

Brazos River near Aspermont, Tex.

USGS station 08080500 DMF Brazos 

River near Aspermont, Tex.

USGS station 08084000 Clear Fork 

Brazos River at Nugent, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

1966 164.1 13.5 150.6 0.08 138.4 8.6 129.7 0.06 87.3 6.2 81.1 0.07

1967 54.3 8.7 45.7 0.16 195.5 8.7 186.8 0.04 22.7 4.1 18.6 0.18

1968 66.6 10.1 56.4 0.15 86.8 11.0 75.8 0.13 53.7 15.7 38.0 0.29

1969 53.2 4.3 49.0 0.08 163.8 15.2 148.6 0.09 99.7 15.0 84.6 0.15

1970 42.1 9.3 32.8 0.22 76.9 9.1 67.8 0.12 36.6 23.1 13.5 0.63

1971 72.1 9.5 62.6 0.13 211.2 11.9 199.3 0.06 103.7 10.1 93.7 0.10

1972 130.6 26.9 103.7 0.21 312.7 27.5 285.2 0.09 55.4 29.6 25.8 0.53

1973 47.8 22.1 25.7 0.46 81.3 28.0 53.3 0.34 54.5 24.3 30.2 0.45

1974 52.4 2.2 50.2 0.04 51.8 8.9 42.9 0.17 61.4 12.1 49.3 0.20

1975 64.9 9.3 55.6 0.14 129.6 15.7 113.9 0.12 183.4 60.3 123.1 0.33

1976 39.9 6.6 33.3 0.17 53.7 7.3 46.4 0.14 31.3 16.3 15.0 0.52

1977 65.5 17.1 48.3 0.26 58.0 9.7 48.3 0.17 50.8 20.0 30.8 0.39

1978 26.7 1.9 24.8 0.07 51.0 4.0 46.9 0.08 24.7 6.7 18.0 0.27

1979 35.4 5.8 29.6 0.16 102.5 17.4 85.2 0.17 28.7 9.3 19.5 0.32

1980 48.0 3.1 44.9 0.06 167.8 3.0 164.8 0.02 47.0 3.6 43.4 0.08

1981 26.2 6.1 20.2 0.23 86.8 21.4 65.3 0.25 127.4 44.6 82.8 0.35

1982 120.2 11.6 108.7 0.10 219.7 41.6 178.1 0.19 155.3 35.9 119.4 0.23

1983 21.1 4.4 16.7 0.21 58.3 6.3 52.0 0.11 24.5 15.2 9.3 0.62

1984 89.1 12.0 77.2 0.13 91.2 9.2 82.0 0.10 15.1 5.8 9.3 0.38

1985 54.8 4.4 50.4 0.08 176.5 33.4 143.1 0.19 39.4 14.6 24.7 0.37

1986 117.9 21.1 96.8 0.18 224.1 52.6 171.5 0.23 59.0 9.8 49.2 0.17

1987 212.2 39.7 172.6 0.19 226.9 53.7 173.2 0.24 317.4 100.5 216.9 0.32

1988 13.8 2.4 11.4 0.17 45.9 6.0 39.9 0.13 40.5 17.3 23.3 0.43

1989 26.8 2.9 23.9 0.11 53.7 5.2 48.5 0.10 25.1 9.9 15.2 0.40

1990 121.2 6.2 115.0 0.05 157.5 17.2 140.3 0.11 99.0 9.5 89.4 0.10

1991 139.1 7.1 132.0 0.05 146.1 14.6 131.4 0.10 115.8 16.8 98.9 0.15

1992 175.1 68.1 107.0 0.39 284.9 65.5 219.4 0.23 324.7 99.4 225.3 0.31

1993 21.6 9.6 12.0 0.44 31.6 8.7 23.0 0.27 40.5 24.0 16.5 0.59

1994 23.2 3.0 20.2 0.13 16.6 0.8 15.8 0.05 49.7 11.6 38.1 0.23

1995 51.8 7.0 44.8 0.14 60.2 0.6 59.6 0.01 48.4 8.4 40.0 0.17

1996 55.2 12.2 43.0 0.22 32.5 1.7 30.8 0.05 24.2 8.4 15.8 0.35

1997 73.3 14.0 59.4 0.19 85.9 20.4 65.5 0.24 74.1 28.8 45.3 0.39

1998 11.7 2.7 9.0 0.23 7.5 2.2 5.4 0.29 6.5 5.1 1.4 0.79
Appendix 1. Hydrographic Separation Results 47

1999 56.0 5.6 50.4 0.10 128.9 5.6 123.4 0.04 8.8 1.3 7.5 0.14

2000 29.8 0.9 28.9 0.03 86.5 5.3 81.2 0.06 17.9 0.3 17.6 0.02

2001 22.4 4.5 17.8 0.20 60.7 37.3 23.4 0.62 23.9 3.9 20.1 0.16

2002 17.0 1.3 15.7 0.08 28.9 7.3 21.6 0.25 18.9 1.7 17.2 0.09

2003 28.7 2.0 26.7 0.07 43.1 9.1 34.0 0.21 14.7 3.4 11.4 0.23

2004 74.7 9.0 65.7 0.12 76.6 21.0 55.6 0.27 11.2 1.3 9.9 0.12

2005 87.4 35.6 51.8 0.41 237.1 37.3 199.9 0.16 20.7 5.2 15.5 0.25

2006 22.6 3.5 19.1 0.16 48.0 11.8 36.2 0.25 20.1 3.2 17.0 0.16

2007 81.9 23.0 58.9 0.28 155.6 64.2 91.4 0.41 135.7 11.8 123.9 0.09

2008 41.5 8.3 33.2 0.20 76.6 16.3 60.3 0.21 33.8 16.3 17.4 0.48

2009 37.3 7.3 30.0 0.20 57.2 30.7 26.5 0.54 10.7 4.5 6.1 0.42

Mean 64.0 11.0 53.0 0.17 111.1 18.0 93.0 0.17 64.6 17.6 47.0 0.30

Median 52.8 7.2 45.3 0.16 86.2 11.4 66.7 0.15 40.5 10.8 24.0 0.28

Minimum 11.7 0.9 9.0 0.03 7.5 0.6 5.4 0.01 6.5 0.3 1.4 0.02

Maximum 212.2 68.1 172.6 0.46 312.7 65.5 285.2 0.62 324.7 100.5 225.3 0.79

Water year

USGS station 08082000 Salt Fork 

Brazos River near Aspermont, Tex.

USGS station 08080500 DMF Brazos 

River near Aspermont, Tex.

USGS station 08084000 Clear Fork 

Brazos River at Nugent, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]
48 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]

Water year

USGS station 08085500 Clear Fork 

Brazos River at Fort Griffin, Tex.

USGS station 08095000 North Bosque 

River near Clifton, Tex.

USGS station 08082500 Brazos 

River at Seymour, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

1966 179.6 16.4 163.2 0.09 163.7 39.9 123.8 0.24 - - - -

1967 29.3 6.7 22.6 0.23 29.9 10.0 19.9 0.34 350.3 57.8 292.5 0.17

1968 139.3 39.7 99.6 0.29 557.6 148.0 409.5 0.27 230.7 50.7 179.9 0.22

1969 226.0 36.2 189.9 0.16 165.4 52.4 113.0 0.32 258.0 30.9 227.2 0.12

1970 69.6 36.4 33.2 0.52 302.2 137.6 164.6 0.46 148.0 37.5 110.4 0.25

1971 274.8 23.5 251.2 0.09 32.8 13.0 19.9 0.40 311.1 22.4 288.7 0.07

1972 106.1 53.4 52.6 0.50 264.9 77.8 187.2 0.29 527.2 135.9 391.3 0.26

1973 174.5 56.8 117.7 0.33 189.7 69.5 120.2 0.37 304.3 99.8 204.5 0.33

1974 106.3 9.2 97.1 0.09 45.7 17.3 28.4 0.38 112.4 4.7 107.6 0.04

1975 311.1 88.2 222.9 0.28 212.7 72.4 140.2 0.34 296.4 58.1 238.3 0.20

1976 46.7 19.2 27.5 0.41 60.0 15.1 45.0 0.25 106.8 31.3 75.5 0.29

1977 116.2 29.1 87.1 0.25 403.5 102.8 300.8 0.25 202.4 53.5 148.9 0.26

1978 544.6 12.2 532.4 0.02 15.6 8.9 6.7 0.57 167.2 9.0 158.2 0.05

1979 102.6 33.8 68.9 0.33 187.3 44.0 143.3 0.24 161.3 42.9 118.4 0.27

1980 159.7 10.1 149.7 0.06 32.1 13.6 18.6 0.42 295.4 31.2 264.2 0.11

1981 355.1 70.2 284.9 0.20 64.3 11.8 52.5 0.18 161.9 35.9 126.0 0.22

1982 446.5 115.7 330.8 0.26 124.5 38.4 86.1 0.31 606.8 187.9 418.9 0.31

1983 61.6 34.0 27.5 0.55 14.7 5.5 9.3 0.37 113.7 35.2 78.5 0.31

1984 24.2 12.5 11.8 0.51 11.7 1.7 10.1 0.14 278.9 53.4 225.5 0.19

1985 202.4 53.9 148.5 0.27 64.9 15.2 49.7 0.23 340.8 85.3 255.5 0.25

1986 127.2 20.4 106.8 0.16 187.7 13.1 174.6 0.07 434.0 98.4 335.6 0.23

1987 620.6 206.5 414.1 0.33 284.9 131.1 153.8 0.46 742.3 201.5 540.8 0.27

1988 80.5 34.2 46.3 0.43 88.3 13.3 75.0 0.15 104.3 25.2 79.0 0.24

1989 68.7 27.2 41.5 0.40 362.6 52.4 310.2 0.14 212.2 32.4 179.8 0.15

1990 385.7 55.2 330.5 0.14 375.1 116.9 258.2 0.31 537.2 80.5 456.7 0.15

1991 339.6 50.0 289.6 0.15 102.4 31.1 71.3 0.30 461.2 64.4 396.8 0.14

1992 951.0 263.5 687.5 0.28 1366.2 273.9 1092.3 0.20 702.7 287.3 415.4 0.41

1993 99.4 54.0 45.4 0.54 197.4 96.4 101.0 0.49 133.7 59.8 73.9 0.45

1994 132.4 27.3 105.1 0.21 243.7 42.6 201.2 0.17 103.1 18.6 84.5 0.18

1995 146.6 27.1 119.5 0.19 602.1 183.4 418.7 0.30 255.0 39.2 215.8 0.15

1996 52.9 24.6 28.3 0.47 103.6 27.4 76.2 0.26 178.5 22.4 156.1 0.13

1997 175.3 60.4 114.9 0.34 747.2 278.3 468.9 0.37 259.6 67.9 191.7 0.26

1998 33.2 17.8 15.4 0.54 328.0 71.4 256.7 0.22 61.1 20.0 41.1 0.33

1999 42.0 8.4 33.6 0.20 32.8 17.9 14.9 0.55 260.2 43.2 217.0 0.17

2000 31.2 2.6 28.6 0.08 39.1 3.0 36.1 0.08 154.0 17.9 136.2 0.12

2001 71.7 15.2 56.6 0.21 219.8 64.6 155.1 0.29 175.6 47.8 127.7 0.27

2002 119.2 13.6 105.6 0.11 175.0 53.5 121.5 0.31 134.0 19.3 114.6 0.14

2003 76.8 9.0 67.8 0.12 67.6 26.8 40.9 0.40 117.3 20.0 97.3 0.17

2004 56.5 9.4 47.1 0.17 332.6 66.6 266.0 0.20 268.6 37.1 231.6 0.14
Appendix 1. Hydrographic Separation Results 49

2005 340.0 42.3 297.7 0.12 364.9 184.9 180.0 0.51 516.6 95.1 421.5 0.18

2006 42.0 8.4 33.5 0.20 23.5 6.3 17.2 0.27 106.2 37.8 68.5 0.36

2007 382.7 55.4 327.3 0.14 879.8 266.8 612.9 0.30 404.3 109.7 294.6 0.27

2008 106.2 41.9 64.3 0.39 100.3 43.3 57.0 0.43 98.3 43.3 55.1 0.44

2009 34.6 7.7 26.9 0.22 24.6 5.5 19.2 0.22 99.6 46.6 53.0 0.47

Mean 186.2 41.8 144.4 0.26 231.7 67.4 164.3 0.30 267.3 60.4 206.8 0.23

Median 117.7 28.2 98.3 0.23 170.2 42.9 116.6 0.30 230.7 43.2 179.9 0.22

Minimum 24.2 2.6 11.8 0.02 11.7 1.7 6.7 0.07 61.1 4.7 41.1 0.04

Maximum 951.0 263.5 687.5 0.55 1366.2 278.3 1092.3 0.57 742.3 287.3 540.8 0.47

Water year

USGS station 08085500 Clear Fork 

Brazos River at Fort Griffin, Tex.

USGS station 08095000 North Bosque 

River near Clifton, Tex.

USGS station 08082500 Brazos 

River at Seymour, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]
50 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]

Water year

USGS station 08088000 Brazos 

River near South Bend, Tex.

USGS station 08089000 Brazos 

River near Palo Pinto, Tex.

USGS station 08090800 Brazos 

River near Dennis, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

1966 1103.1 170.9 932.2 0.15 1275.1 228.0 1047.1 0.18 - - - -

1967 517.9 121.5 396.4 0.23 522.6 71.8 450.8 0.14 - - - -

1968 680.2 161.6 518.6 0.24 1015.9 139.0 876.9 0.14 - - - -

1969 889.2 138.5 750.7 0.16 1173.2 303.9 869.3 0.26 1556.8 333.8 1223.0 0.21

1970 404.9 163.1 241.8 0.40 568.4 83.0 485.4 0.15 1073.5 226.6 846.9 0.21

1971 744.9 88.6 656.2 0.12 362.3 23.6 338.8 0.07 365.8 50.0 315.7 0.14

1972 744.3 242.3 501.9 0.33 664.6 128.7 535.9 0.19 776.4 246.4 530.0 0.32

1973 613.2 231.2 381.9 0.38 794.5 111.5 683.0 0.14 958.7 248.4 710.3 0.26

1974 298.5 30.5 268.0 0.10 202.2 27.4 174.8 0.14 271.7 45.2 226.6 0.17

1975 859.3 240.2 619.1 0.28 1177.9 255.9 922.1 0.22 1566.4 405.4 1161.0 0.26

1976 203.6 80.2 123.5 0.39 213.2 38.7 174.6 0.18 283.9 73.2 210.7 0.26

1977 424.8 123.1 301.7 0.29 588.1 138.3 449.8 0.24 903.3 242.9 660.4 0.27

1978 900.9 29.5 871.5 0.03 765.3 28.9 736.4 0.04 794.3 48.9 745.4 0.06

1979 355.2 108.7 246.6 0.31 417.7 114.0 303.6 0.27 567.8 223.6 344.3 0.39

1980 383.6 62.1 321.5 0.16 317.4 48.7 268.8 0.15 361.1 117.3 243.8 0.32

1981 804.8 177.7 627.1 0.22 966.9 103.3 863.6 0.11 948.1 208.6 739.5 0.22

1982 2188.6 649.4 1539.3 0.30 2889.3 271.9 2617.4 0.09 4139.2 309.6 3829.6 0.07

1983 225.9 114.7 111.2 0.51 287.5 56.1 231.4 0.20 437.0 102.7 334.4 0.23

1984 262.8 83.9 178.9 0.32 213.2 48.2 165.0 0.23 258.1 81.9 176.3 0.32

1985 803.0 268.8 534.1 0.33 741.3 97.3 644.1 0.13 1001.0 222.0 779.0 0.22

1986 650.0 114.5 535.5 0.18 527.4 77.6 449.8 0.15 630.3 133.1 497.2 0.21

1987 1479.8 534.8 945.0 0.36 2100.1 455.5 1644.6 0.22 2166.0 598.5 1567.5 0.28

1988 206.6 67.1 139.5 0.32 98.5 24.6 73.9 0.25 120.0 32.0 88.0 0.27

1989 467.1 73.5 393.6 0.16 577.6 76.4 501.2 0.13 1183.1 261.2 921.9 0.22

1990 1712.7 243.2 1469.5 0.14 2176.8 250.1 1926.7 0.11 2949.0 715.7 2233.3 0.24

1991 925.3 192.1 733.2 0.21 1256.4 210.6 1045.9 0.17 1142.9 432.6 710.3 0.38

1992 2965.7 879.3 2086.4 0.30 3339.4 844.2 2495.2 0.25 4054.4 1122.7 2931.7 0.28

1993 378.0 210.8 167.2 0.56 455.7 136.8 318.9 0.30 529.2 230.5 298.7 0.44

1994 314.5 72.0 242.5 0.23 353.3 65.0 288.4 0.18 577.2 130.5 446.7 0.23

1995 482.1 129.8 352.2 0.27 632.2 184.1 448.1 0.29 899.7 276.6 623.1 0.31

1996 296.7 68.3 228.4 0.23 415.4 74.1 341.4 0.18 512.6 100.7 411.9 0.20

1997 929.1 216.3 712.8 0.23 1380.2 234.6 1145.6 0.17 2231.5 573.5 1658.0 0.26

1998 188.7 49.6 139.1 0.26 367.3 76.8 290.5 0.21 432.3 127.9 304.4 0.30

1999 278.9 50.7 228.2 0.18 201.4 53.7 147.7 0.27 246.5 91.0 155.5 0.37

2000 174.5 25.3 149.2 0.14 113.7 56.1 57.6 0.49 134.5 56.2 78.3 0.42

2001 405.3 107.3 298.1 0.26 535.0 117.5 417.5 0.22 792.4 215.5 576.9 0.27

2002 307.4 57.0 250.4 0.19 239.7 55.8 184.0 0.23 288.5 103.7 184.7 0.36

2003 214.7 40.5 174.3 0.19 222.0 76.9 145.1 0.35 231.8 96.4 135.3 0.42

2004 514.9 122.0 392.9 0.24 281.0 67.6 213.4 0.24 354.8 98.9 255.9 0.28
Appendix 1. Hydrographic Separation Results 51

2005 1278.2 244.8 1033.4 0.19 1137.9 204.7 933.2 0.18 1006.4 270.6 735.7 0.27

2006 203.8 74.4 129.4 0.37 261.6 89.8 171.8 0.34 250.4 114.5 135.9 0.46

2007 1376.9 305.0 1071.9 0.22 1736.9 218.7 1518.3 0.13 2497.2 432.3 2064.9 0.17

2008 264.4 93.3 171.1 0.35 293.2 92.6 200.6 0.32 444.7 126.6 318.1 0.28

2009 160.7 68.4 92.3 0.43 141.3 86.2 55.0 0.61 177.7 88.5 89.2 0.50

Mean 672.4 166.5 505.9 0.26 772.8 139.7 633.0 0.21 978.4 234.5 743.9 0.28

Median 474.6 118.1 367.1 0.24 531.2 91.2 449.0 0.19 630.3 208.6 497.2 0.27

Minimum 160.7 25.3 92.3 0.03 98.5 23.6 55.0 0.04 120.0 32.0 78.3 0.06

Maximum 2965.7 879.3 2086.4 0.56 3339.4 844.2 2617.4 0.61 4139.2 1122.7 3829.6 0.50

Water year

USGS station 08088000 Brazos 

River near South Bend, Tex.

USGS station 08089000 Brazos 

River near Palo Pinto, Tex.

USGS station 08090800 Brazos 

River near Dennis, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts measured at selected U.S. Geological 

Survey (USGS) streamflow-gaging stations in the upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, runoff; BFI, base-flow index (defined as BF/Q);

 -, no data available]
52 Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts 

measured at selected U.S. Geological Survey (USGS) streamflow-gaging stations in the 

upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, 

runoff; BFI, base-flow index (defined as BF/Q); -, no data available]

Water year

USGS station 08091000 Brazos 

River near Glen Rose, Tex.

USGS station 08091500 Paluxy 

River at Glen Rose, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

1966 1870.1 360.7 1509.3 0.19 49.7 12.4 37.3 0.25

1967 677.7 189.7 488.0 0.28 23.2 7.3 15.9 0.31

1968 1743.5 461.5 1282.0 0.26 195.0 57.7 137.4 0.30

1969 1606.0 335.3 1270.7 0.21 121.7 59.4 62.3 0.49

1970 888.8 94.0 794.9 0.11 109.9 57.1 52.8 0.52

1971 330.4 84.6 245.8 0.26 28.5 11.0 17.4 0.39

1972 936.7 346.5 590.2 0.37 74.4 21.9 52.5 0.29

1973 1222.0 312.7 909.3 0.26 123.9 32.6 91.4 0.26

1974 277.4 88.8 188.6 0.32 17.4 10.5 6.9 0.60

1975 1921.5 422.9 1498.6 0.22 69.1 30.8 38.3 0.45

1976 342.0 64.2 277.7 0.19 39.1 8.1 31.0 0.21

1977 915.8 230.4 685.4 0.25 94.9 33.3 61.6 0.35

1978 676.5 57.6 618.9 0.09 8.8 5.1 3.7 0.58

1979 769.1 146.7 622.4 0.19 103.7 21.9 81.8 0.21

1980 284.7 56.5 228.2 0.20 14.7 6.4 8.3 0.44

1981 942.9 187.4 755.5 0.20 8.7 2.9 5.7 0.34

1982 4384.0 240.7 4143.3 0.05 98.3 29.2 69.1 0.30

1983 374.5 31.4 343.1 0.08 10.1 7.6 2.5 0.75

1984 262.5 11.8 250.7 0.04 6.2 2.3 4.0 0.36

1985 1076.4 139.7 936.7 0.13 37.3 10.4 26.9 0.28

1986 736.2 84.7 651.5 0.12 76.2 9.4 66.9 0.12

1987 2365.0 607.1 1757.9 0.26 75.8 30.1 45.7 0.40

1988 115.2 33.0 82.2 0.29 17.1 5.5 11.6 0.32

1989 1424.2 77.6 1346.6 0.05 203.0 22.5 180.5 0.11

1990 3252.1 960.0 2292.1 0.30 193.8 60.8 133.0 0.31

1991 1277.4 114.2 1163.2 0.09 29.0 17.8 11.3 0.61

1992 4605.1 749.3 3855.9 0.16 361.3 121.5 239.9 0.34

1993 551.3 180.1 371.2 0.33 78.0 54.0 24.0 0.69

1994 643.2 90.4 552.7 0.14 56.1 18.9 37.2 0.34

1995 1033.8 143.1 890.7 0.14 235.0 60.3 174.7 0.26

1996 486.0 48.1 437.8 0.10 34.2 18.7 15.5 0.55

1997 2774.5 677.0 2097.5 0.24 244.4 96.0 148.4 0.39

1998 656.0 82.1 573.9 0.13 99.1 33.8 65.4 0.34

1999 196.3 55.2 141.1 0.28 19.5 10.5 9.0 0.54

2000 122.8 25.8 97.0 0.21 17.3 5.8 11.5 0.33

2001 1074.6 310.8 763.8 0.29 106.0 48.2 57.8 0.45

2002 326.3 54.1 272.2 0.17 58.1 24.4 33.6 0.42

2003 169.8 36.9 132.9 0.22 29.0 16.9 12.1 0.58

2004 473.6 44.4 429.3 0.09 67.2 18.2 49.0 0.27
Appendix 1. Hydrographic Separation Results 53

2005 983.3 192.3 791.0 0.20 59.3 39.4 19.9 0.66

2006 218.4 27.3 191.1 0.13 23.1 3.4 19.7 0.15

2007 2910.3 556.4 2353.8 0.19 263.6 55.9 207.8 0.21

2008 406.5 77.7 328.8 0.19 43.5 18.3 25.3 0.42

2009 73.8 27.6 46.2 0.37 11.3 4.5 6.8 0.40

Mean 1099.5 207.2 892.3 0.19 82.6 27.8 54.8 0.38

Median 752.7 104.1 620.7 0.19 58.7 18.8 35.4 0.35

Minimum 73.8 11.8 46.2 0.04 6.2 2.3 2.5 0.11

Maximum 4605.1 960.0 4143.3 0.37 361.3 121.5 239.9 0.75

Water year

USGS station 08091000 Brazos 

River near Glen Rose, Tex.

USGS station 08091500 Paluxy 

River at Glen Rose, Tex.

Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI Q (ft3/s) BF (ft3/s) RO (ft3/s) BFI

Publishing support provided by

the Lafayette Publishing Service Center

Appendix 1. Hydrographic separation results for long-term annual streamflow amounts 

measured at selected U.S. Geological Survey (USGS) streamflow-gaging stations in the 

upper Brazos River Basin, Texas.—Continued

[DMF, Double Mountain Fork; Q, annual mean streamflow; ft3/s, cubic feet per second; BF, base flow; RO, 

runoff; BFI, base-flow index (defined as BF/Q); -, no data available]

Baldys, S., and Schalla, F.—Base Flow (1966–2009) and Streamflow Gain and Loss (2010) of the Brazos River from the New Mexico–

Texas State Line to Waco, Texas—SIR 2011–5224

Printed on recycled paper

ISBN 978-1-4113-3318-5

9 7 81411 3331 8 5