Prepared in cooperation with the Texas Water Development Board

A Historical Perspective on Precipitation, Drought Severity, 

and Streamflow in Texas during 1951–56 and 2011

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2013–5113
Front and Back Covers: Photograph of the dry lake bed at O.C. Fisher Lake at 

San Angelo, Texas, July 15, 2011. The lake is downstream from U.S. Geological Survey 

streamflow-gaging station 08134000 North Concho River near Carlsbad, Texas.

Back Cover: Inset photographs looking upstream from U.S. Geological Survey 

streamflow-gaging station 08148500 North Llano River near Junction, Texas (left) 

October 30, 2006, and (right) July 28, 2011.
A Historical Perspective on Precipitation, 

Drought Severity, and Streamflow in 

Texas during 1951–56 and 2011

By Karl E. Winters

Prepared in cooperation with the Texas Water Development Board

Scientific Investigations Report 2013–5113

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director 

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Winters, K.E., 2013, A historical perspective on precipitation, drought severity, and streamflow in Texas during 

1951–56 and 2011: U.S. Geological Survey Scientific Investigations Report 2013–5113, 24 p., http://pubs.usgs.gov/

sir/2013/5113/.
iii

Contents

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

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

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

Previous Studies ...................................................................................................................................2

Description of the Study Area ............................................................................................................2

Methods...........................................................................................................................................................5

Precipitation...........................................................................................................................................5

Drought Severity ...................................................................................................................................5

Streamflow.............................................................................................................................................6

Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas 

during 1951–56 and 2011..................................................................................................................7

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

Drought Severity ...................................................................................................................................7

Streamflow.............................................................................................................................................9

Summary........................................................................................................................................................23

References....................................................................................................................................................24

Figures

1. Map showing locations of unregulated U.S. Geological Survey streamflow-gaging

stations in Texas with complete records during the droughts of 1951–56 and 2011 .........3

2. Maps showing average annual precipitation in Texas; total precipitation during 

the 1956 calendar year; and the 2011 water year....................................................................4

3. Graph showing magnitude and extent of the drought in Texas during October 1,

2010, to September 20, 2012 ........................................................................................................8

4. Graphs showing monthly Palmer Drought Severity Index for Texas during

1900–2012 and annual runoff for Texas during 1901–2011 .....................................................9

5. Graph showing relation between Palmer Drought Severity Index and annual 

runoff for all U.S. Geological Survey streamflow-gaging stations in Texas during 

1901–2011 .....................................................................................................................................10

6. Graphs showing annual mean streamflow at selected unregulated U.S. Geological

Survey streamflow-gaging stations in Texas during 1951–56 and 2011 ............................11

7. Graphs showing streamflow duration for selected unregulated U.S. Geological

Survey streamflow-gaging stations in Texas for 1956, 2011, and the period 

 of record.......................................................................................................................................12

8. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 07233500 Palo Duro Creek near Spearman, Texas...................................................14

9. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 07343000 North Sulphur River near Cooper, Texas ..................................................14

10. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 07346070 Little Cypress Creek near Jefferson, Texas .............................................15
iv

Figures—Continued

11. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08041500 Village Creek near Kountze, Texas ............................................................15

12. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08068500 Spring Creek near Spring, Texas ...............................................................16

13. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08070000 East Fork San Jacinto River near Cleveland, Texas ...............................16

14. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08070500 Caney Creek near Splendora, Texas .........................................................17

15. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08071000 Peach Creek at Splendora, Texas..............................................................17

16. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08134000 North Concho River near Carlsbad, Texas ...............................................18

17. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08148500 North Llano River near Junction, Texas ...................................................18

18. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08150000 Llano River near Junction, Texas...............................................................19

19. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08164000 Lavaca River near Edna, Texas ..................................................................19

20. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08166000 Johnson Creek near Ingram, Texas...........................................................20

21. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08167500 Guadalupe River near Spring Branch, Texas...........................................20

22. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08171000 Blanco River at Wimberley, Texas.............................................................21

23. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08189500 Mission River at Refugio, Texas.................................................................21

24. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08195000 Frio River at Concan, Texas ........................................................................22

25. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08198000 Sabinal River near Sabinal, Texas .............................................................22

26. Hydrograph showing streamflow duration and daily mean streamflow during

January 2010 to September 2012 for U.S. Geological Survey streamflow-gaging

station 08205500 Frio River near Derby, Texas.......................................................................23
v

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

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

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

(NAVD 88).

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

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

calendar year in which it ends.

Tables

1. Classification of drought severity by the Palmer Drought Severity Index and by 

the Drought Monitor.....................................................................................................................5

2. Unregulated U.S. Geological Survey streamflow-gaging stations in Texas with

complete record during the droughts of 1951–56 and 2011. .................................................6

3. Twelve-month statewide average precipitation for selected water years in Texas.........7

4. Monthly statewide Palmer Drought Severity Index (PDSI) during the 1951–56 and

2011 droughts in Texas.................................................................................................................8

A Historical Perspective on Precipitation, 

Drought Severity, and Streamflow in 

Texas during 1951–56 and 2011

By Karl E. Winters

Abstract

The intense drought throughout Texas during 2011 

resulted in substantial declines in streamflow. By April 2011, 

nearly all of the State was experiencing severe to extreme 

drought according to data from the University of Nebraska–

Lincoln Drought Monitor. By the end of July 2011, more than 

75 percent of the State was experiencing exceptional drought. 

The worst of the drought occurred around October 4, 2011, 

when 97 percent of Texas was suffering from extreme to 

exceptional drought. The historical drought of 1951–56 has 

long been used by water-resource managers, engineers, and 

scientists as a point of reference for water-supply planning. 

A comparison of drought conditions during the 2011 water 

year (October 1, 2010, through September 30, 2011) to the 

historical drought of 1951–56 from a hydrologic perspective 

serves as an additional reference for water-supply planning. 

A record low statewide average annual precipitation of 

11.27 inches for the period 1895–2011 was recorded during 

the 2011 water year; the prior record low statewide average 

precipitation was 13.91 inches during the 1956 water year. 

The statewide monthly Palmer Drought Severity Index (PDSI) 

declined to -7.93 during September 2011, which was larger 

in magnitude than the statewide PDSI during any droughtaffected month in the 1950s.

Annual mean streamflow and streamflow-duration curves 

for the 1951–56 and 2011 water years were assessed for 

19 unregulated U.S. Geological Survey (USGS) streamflowgaging stations. At eight of these streamflow-gaging 

stations, the annual mean streamflow was lower in 2011 

than for any year during 1951–56; many of these stations 

are located in eastern Texas. Annual mean streamflows for 

streamflow-gaging stations in the Guadalupe, Blanco, and 

upper Frio River Basins were lower in 1956 than in 2011. 

The streamflow-duration curves for many streamflow-gaging 

stations indicate a lack of (or diminished) storm runoff during 

2011. Low streamflows (those exceeded 90 to 95 percent of 

days) were lower for 1956 than for 2011 at seven streamflowgaging stations. For most of these stations, the lowest of the 

low streamflows during 1951–56 occurred in 1956. During 

March to September 2011, record daily lows were measured at 

USGS streamflow-gaging station 08041500 Village Creek near 

Kountze, Tex., which has more than 70 years of record. Many 

other USGS streamflow-gaging stations in Texas started the 

2011 water year with normal streamflow but by the end of the 

water year were flowing at near-record lows.

Introduction

In 2011, there was a severe drought in Texas, and scant 

precipitation fell throughout most of the State. Record high 

temperatures during June through August 2011 (Dallas 

Morning News, 2011) combined with the scant precipitation 

to help produce record low streamflows throughout the State. 

By August 4, 2011, the precipitation deficit was so severe that 

State Climatologist John Nielsen-Gammon declared 2011 to 

be the worst 1-year drought on record in Texas (Texas A&M 

University, 2011). A record low statewide average annual 

precipitation of 11.27 inches for the period 1895–2011 was 

recorded during the 2011 water year; the prior record low 

statewide average precipitation was 13.91 inches during the 

1956 water year. (A water year is the 12-month period from 

October 1 through September 30 designated by the calendar 

year in which it ends.)

Drought conditions prevailed in Texas from 1947 to 

1957, with the most severe years of drought occurring in the 

1950s, providing historical perspective for the 2011 drought. 

The years of 1951 through 1956 in particular have long been 

used by water-resource managers, engineers, and scientists 

as a point of reference for water-supply planning (Texas 

Water Development Board, 2013). A comparison of the 

2011 drought to the drought of 1951–56 from a hydrologic 

perspective serves as an additional reference for water-supply 

planning. Accordingly, in 2012, the U.S. Geological Survey 

(USGS), in cooperation with the Texas Water Development 

Board (TWDB), assessed the effects of the 1951–56 and 2011 

droughts from a hydrologic perspective.
2 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

Purpose and Scope

The purpose of this report is to document precipitation, 

drought severity, and streamflow in Texas during the droughts 

of 1951–56 and 2011. Isohyetal maps are presented for the 

purpose of comparing normal annual precipitation in Texas 

and total precipitation during the 1956 and 2011 water years. 

The magnitude and extent of the 2011 drought in Texas are 

described by using the Palmer Drought Severity Index (PDSI) 

(Palmer, 1965) and by using the Drought Monitor’s drought 

severity classification (University of Nebraska–Lincoln, 2012). 

For historical perspective on the 1951–56 and 2011 droughts, 

precipitation, drought severity, and statewide runoff data 

were analyzed from 1895–2011, 1900–2011, and 1901–2011, 

respectively. Annual mean streamflows for 19 unregulated 

streamflow-gaging stations in Texas are presented for the 

1951–56 and 2011 water years, and streamflow-duration 

curves are presented for these stations for 1956 and 2011. 

Comparisons are made between the 1951–56 and 2011 

droughts. Drought severity is discussed using (aggregate) 

statewide data and not with respect to climatic divisions within 

the State. This report does not discuss the effects of drought 

on lakes or groundwater levels or the effects of drought on 

agriculture, water quality, or habitat.

Previous Studies

The Texas State Climatologist reported on precipitation 

deficits during the 2011 drought (Nielsen-Gammon, 2011). 

That report details the use of a Standardized Precipitation 

Index (SPI) (U.S. Department of Commerce, National 

Climatic Data Center, 2012) and provides maps showing 

the SPI for each county in Texas during October 2010 to 

October 2011. The SPI relates precipitation recorded during a 

specific period to the historical precipitation record at a given 

location. Texas has 10 climatic divisions (U.S. Department 

of Agriculture, National Agriculture Statistics Service, 2013) 

recognized by climatologists for purposes of data aggregation 

and scientific investigations. The report by Nielsen-Gammon 

(2011) also presents PDSI values throughout Texas for 

13 drought periods during 1900–2011. 

Thomas and others (1963) reported on the effects of 

drought in central and south Texas during 1942–56 and 

noted that many streams in central Texas formerly regarded 

as perennial had ceased flowing during drought years. 

Nace and Pluhowski (1965) reported on the drought of the 

1950s in Colorado, Iowa, Kansas, Missouri, New Mexico, 

Oklahoma, and Texas. Those authors noted that Texas had the 

greatest precipitation deficiency in the United States during 

the 1951–56 drought, and that discharge on many unregulated 

streams in Texas diminished to record-breaking lows, 

including no-flow conditions. Those authors also noted that, 

as early as 1953, streamflow in the Texas Panhandle region 

returned to normal.

Asquith and others (2007) reported the occurrence of 

zero flows at USGS streamflow-gaging stations in Texas. 

Graphs of the annual percentage of zero flow through 2003 

are presented for each station. Asquith and Heitmuller (2008) 

reported trends in mean and harmonic mean streamflows for 

620 streamflow-gaging stations in Texas. Although accounting 

for changes in streamflow over time was beyond the scope 

of this report, the reports by Asquith and others (2007) and 

Asquith and Heitmuller (2008) may help to inform the reader 

as to whether streamflows at a particular streamflow-gaging 

station may have changed over time.

Description of the Study Area

 The study area is Texas (fig. 1). Average annual 

precipitation in Texas ranges from about 9 inches in the 

western part of the State to more than 50 inches in the 

southeastern part of the State (fig. 2A). Statewide average 

annual precipitation is 27.95 inches. Figure 1 depicts the 

location of the long-term unregulated streamflow-gaging 

stations with complete record for the 1951–56 and 2011 water 

years. These streamflow-gaging stations are generally in 

south-central and eastern Texas, with one station in the Texas 

Panhandle (fig. 1). Relatively few perennial streams exist in 

western Texas, and no USGS streamflow‐gaging stations in 

that part of the State have complete streamflow record for the 

periods 1951–56 and 2011. Streamflows at stations on the 

Colorado, Brazos, and Trinity Rivers are regulated and not 

discussed in this report. 
Introduction 3

O C Fisher Lake

TEXAS

Spearman

Cooper

Jefferson

Carlsbad

Junction

Ingram

Concan

Sabinal

Derby

Spring

Branch

Wimberley

Refugio

Edna

Kountze

San Antonio

Houston

Fort

 Worth

Dallas

Amarillo

El Paso

07233500

07343000

08134000

08148500

08150000

08166000

08205500

08198000 08167500

08171000

08189500

08041500

07346070

08164000

08195000 San Antonio River

Palo Duro Creek

North Llano 

River

Johnson

Creek

Colorado

Nueces

River

Blanco

River

River

River

Brazos

Red River

Prairie Dog Town Fork Red River

North Concho River

Llano River

Little Cypress

Creek

Sabine River

Frio River

River Sabinal

Guadalupe River

Lavaca River

Canadian River

Cypress Creek

North Sulphur River

Neches Rive r

Trinity

River

Village

Creek

Rio Grande

Mission

River Gulf of Mexico

Area enlarged

Caney Creek

Peach

Creek

San Jacinto River

Spring Creek

East Fork

San Jacinto River

Spring

Cleveland

Splendora

08068500

08070000

08071000 08070500 0 50 100 MILES

0 50 100 KILOMETERS

TEXAS

NEW 

MEXICO

OKLAHOMAARKANSAS

LOUISIANA

U.S. Geological Survey 

 streamflow-gaging 

 station and number

08195000

EXPLANATION

98 ̊ 96 ̊

102 ̊ 100 ̊

36 ̊

34 ̊

32 ̊ 106 ̊ 104 ̊

30 ̊

28 ̊

26 ̊

94 ̊

Base modified from U.S. Geological Survey 1:250,000-scale digital data

Texas Centric Mapping System, Albers Equal Area projection

North American Datum of 1983

Figure 1. Locations of unregulated U.S. Geological Survey streamflow-gaging stations in Texas with complete records

during the droughts of 1951–56 and 2011.

Figure 1. Locations of unregulated U.S. Geological Survey streamflow-gaging stations in Texas with complete records during 

the droughts of 1951–56 and 2011.
4 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

N

C. Total precipitation during 2011 water year (October 1, 2010–September 30, 2011)

B. Total precipitation during 1956 calendar year

A. Average annual precipitation

Precipitation, in inches—

 Interval varies

 0 to 5

 Greater than 5 to 10

 Greater than 10 to 20

 Greater than 20 to 30

 Greater than 30 to 40

 Greater than 40 to 50

 Greater than 50 

EXPLANATION

Figure 2. A, Average annual precipitation in Texas (National Weather Service, 2012); total

precipitation during B, the 1956 calendar year (modified from U.S. Department of Commerce,

Weather Bureau, 1957); and C, the 2011 water year (modified from National Weather Service, 2012). 

Figure 2. A, Average annual precipitation in Texas (National Weather Service, 2012); 

total precipitation during B, the 1956 calendar year (modified from U.S. Department of 

Commerce, Weather Bureau, 1957); and C, the 2011 water year (National Weather Service, 

2012).
Methods 5

Methods

Precipitation, drought severity, and streamflow were 

summarized for the droughts of 1951–56 and 2011 by using 

previously published data obtained from various sources. 

The U.S. Department of Commerce, the Drought Monitor, 

and the U.S. Geological Survey were the primary sources of 

these data. All of the sources of data are described in detail in 

the following discussions pertaining to precipitation, drought 

severity and streamflow.

Precipitation

Statewide average annual precipitation data for Texas 

were obtained from the National Climatic Data Center 

(NCDC) (U.S. Department of Commerce, National Climatic 

Data Center, 2012) for the years 1895–2011. The 12-month 

statewide averages were ranked by water year from lowest 

to highest to assess the 1951–56 and 2011 precipitation 

amounts and to compare those amounts to the average annual 

precipitation. Additionally, isohyetal maps showing lines 

of equal precipitation (Jain and Singh, 2005) are presented 

in figure 2 showing average annual precipitation in Texas 

and total precipitation during calendar year 1956 and 

water year 2011. Isohyetal maps showing average annual 

precipitation and total precipitation during the 2011 water 

year were obtained from the National Weather Service’s 

Advanced Hydrologic Prediction Service (National Weather 

Service, 2012). The isohyetal map for the 1956 calendar year 

was obtained from the Weather Bureau (now the National 

Weather Service) climatological data summary for 1956 (U.S. 

Department of Commerce, 1957).

Drought Severity

Two drought severity classifications (table 1) were used 

to assess the intensity of drought in Texas during 1951–56 and 

2011. The PDSI is a quantitative assessment of soil moisture 

based on precipitation and temperature data (Palmer, 1965). 

PDSI values greater than 0.49 corresponding to wetter than 

normal conditions are not shown in table 1. The NCDC 

calculates monthly and annual PDSI values for each State and 

for each climatic division. Texas has 10 climatic divisions 

(U.S. Department of Agriculture, National Agriculture 

Statistics Service, 2013) recognized by climatologists for 

purposes of data aggregation and scientific assessment; 

assessment of drought severity by climatic division is beyond 

the scope of this report. The Drought Monitor, a public 

service operated by the University of Nebraska–Lincoln, 

classifies drought into five qualitative categories (table 1; 

University of Nebraska–Lincoln, 2012). Areal percentages 

of Texas corresponding to the various drought categories 

at weekly intervals during 2011 were obtained from the 

Drought Monitor.

Table 1. Classification of drought severity by the Palmer Drought Severity Index and by the 

Drought Monitor.

[Each classification system is different, and the classification indexes and categories are not equivalent. Palmer 

Drought Severity Index from Palmer, 1965; Drought Monitor from University of Nebraska-Lincoln, 2012]

Palmer Drought Severity Index classifications Drought Monitor classifications

Palmer Drought 

Severity Index Class Drought category Description

0.49 to -0.49 Near normal

-0.50 to -0.99 Incipient drought D0 Abnormally dry

-1.00 to -1.99 Mild drought D1 Moderate drought

-2.00 to -2.99 Moderate drought D2 Severe drought

-3.00 to -3.99 Severe drought D3 Extreme drought

Less than -3.99 Extreme drought D4 Exceptional drought
6 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

Table 2. Unregulated U.S. Geological Survey streamflow-gaging stations in Texas with complete record 

during the droughts of 1951–56 and 2011. 

Station 

number Station name

Contributing 

drainage area 

(square miles)

 Period of record

07233500 Palo Duro Creek near Spearman, Tex. 556 1945–79, 1999–2011

07343000 North Sulphur River near Cooper, Tex. 276 1950–2011

07346070 Little Cypress Creek near Jefferson, Tex. 675 1946–2011

08041500 Village Creek near Kountze, Tex. 860 1939–2011

08068500 Spring Creek near Spring, Tex. 409 1939–2011

08070000 East Fork San Jacinto River near Cleveland, Tex. 325 1939–2011

08070500 Caney Creek near Splendora, Tex. 105 1944–2011

08071000 Peach Creek at Splendora, Tex. 117 1944–77, 1999–2011

08134000 North Concho River near Carlsbad, Tex. 1,191 1924–2011

08148500 North Llano River near Junction, Tex. 914 1916–77, 2001–2011

08150000 Llano River near Junction, Tex. 1,849 1916–93, 1998–2011

08164000 Lavaca River near Edna, Tex. 817 1938–2011

08166000 Johnson Creek near Ingram, Tex. 114 1941–59, 1962–93, 

1999–2011

08167500 Guadalupe River near Spring Branch, Tex. 1,315 1922–2011

08171000 Blanco River at Wimberley, Tex. 355 1924–26, 1928–2011

08189500 Mission River at Refugio, Tex. 690 1939–2011

08195000 Frio River at Concan, Tex. 389 1931–2011

08198000 Sabinal River near Sabinal, Tex. 206 1943–2011

08205500 Frio River near Derby, Tex. 3,429 1915–2011

Streamflow

Streamflow data for 19 unregulated USGS 

streamflow‐gaging stations (fig. 1; table 2) were used to assess 

the effects of drought during 1951–56 and 2011. These data 

include annual and daily mean streamflow obtained from 

the USGS National Water Information System (NWIS; U.S. 

Geological Survey, 2012a). Only stations with complete 

record during 1951–56 and 2011 were used in this study. 

Additionally, stations flagged as “regulated” in the NWIS 

peak-flow file (http://nwis.waterdata.usgs.gov/tx/nwis/

peak) were not included in the analyses. As described by 

Asquith (2001), two commonly used simple classification 

schemes consider regulated stations as (1) those where at 

least 10 percent of the drainage area of the basin is affected 

or controlled by reservoirs, or (2) regulated to the degree 

that annual peak streamflows are likely to be affected. USGS 

hydrologists assign a numeric code of “6” in the peak-flow file 

to designate peak streamflows affected by regulation.

USGS station 07233500 Palo Duro Creek near Spearman, 

Tex. (hereinafter the Palo Duro gage), has a small diversion 

upstream for irrigation. Data for this station are included in 

this report because no other unregulated station is available 

in the Texas Panhandle with complete record during 1951–56 

and 2011. In this report, USGS streamflow-gaging stations 

are frequently referred to by their station number followed by 

their station name (table 2).

Annual runoff, in inches (computed as the average flow 

per unit area for streamflow-gaging stations in Texas), for the 

State of Texas for the period 1901–2011 was obtained from 

the USGS WaterWatch Web page (U.S. Geological Survey, 

2012b). This runoff is based on the entire network of USGS 

streamflow-gaging stations in Texas, including streams 

that are affected by regulation. Compared to annual runoff 

values computed since about 1925, annual runoff values 

computed from about 1901 to about 1924 are likely to be 

much less accurate because few stations were in operation 

before 1924. An assessment of the effect of the number of 

streamflow-gaging stations on the accuracy of statewide runoff 

computations is beyond the scope of this report.

Streamflow-duration curves (Searcy, 1959) describe 

the percentage of time that a given streamflow was equaled 

or exceeded at a site. The median streamflow is exceeded 

50 percent of the time. Streamflow values exceeded only 

5 or 10 percent of the time usually represent storm runoff, 

and a steeply-sloped curve indicates a greater magnitude and 

frequency of storm flows. On the drier end of the spectrum, 

streamflows exceeded 95 percent of the time typically are 
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 7

indicative of low flows that occur in Texas during August and 

September. Streamflow-duration curves were computed for the 

19 unregulated USGS streamflow-gaging stations (table 2), 

for water years 1956 and 2011, and (for comparison) for the 

period of record (1956 was selected to represent the 1951–56 

drought for the streamflow-duration assessment). Streamflowduration curves were based on daily mean streamflow data 

obtained from NWIS and computed by using the USGS 

Automated Data Processing System (U.S. Geological Survey, 

2008). Computations included daily mean streamflows that 

were equaled or exceeded 5, 10, 25, 50, 75, 90, and 95 percent 

of the time.

Additionally, daily streamflow-duration data for the 

period of record for each of the 19 unregulated USGS 

streamflow-gaging stations in table 2 were obtained from 

USGS WaterWatch (U.S. Geological Survey, 2012b). These 

data indicate the percentage of time that a given streamflow 

was not exceeded for a specific date (for example, during all 

of the August 15ths in the period of record). 

Historical Perspective on Precipitation, 

Drought Severity, and Streamflow in 

Texas during 1951–56 and 2011

The magnitude of the 2011 drought in Texas is best 

understood by comparing selected metrics of drought from 

1951–56 with those measured in 2011. Precipitation, drought 

severity, and streamflow are the metrics used to gain a 

historical perspective on the 2011 severe drought compared to 

drought conditions during 1951–56.

Precipitation

Statewide average annual precipitation is 27.95 inches. 

Statewide average precipitation for the 1951–56 and 2011 

water years is shown in table 3. Also shown is the ranking 

(lowest to highest) for each of those years relative to the 

period 1895–2011. Prior to 2011, the driest 1-year period 

was the 1956 water year, when Texas received only about 

50 percent of its normal annual precipitation. During the 2011 

water year, Texas received only about 40 percent of its normal 

annual precipitation.

Isohyetal maps of total precipitation in Texas during 

1956 and 2011 are shown in figures 2B and 2C, respectively. 

Figure 2C highlights the extent of the 2011 drought 

when large parts of Texas received less than 10 inches of 

precipitation during the year. During 2011, few storms in 

Texas generated more than about an inch of precipitation 

(National Weather Service, 2012); thus, a larger fraction 

of the precipitation evaporated or entered the ground as 

infiltration rather than contributing to streamflow. Asquith and 

Roussel (2007) reported the initial abstraction (the amount of 

precipitation that infiltrates before any runoff is generated) 

for 92 watersheds in Texas. The median initial abstraction for 

41 undeveloped watersheds was 1.1 inches, which indicates 

storms producing 1.1 inches or less rainfall likely do not 

generate runoff. Because the analysis by Asquith and Roussel 

(2007) was performed only for storms that generated runoff, 

larger amounts of initial abstraction may have occurred but 

not detected during periods of extreme soil moisture deficits 

such as the 2011 drought (William Asquith, U.S. Geological 

Survey, written commun., 2012).

Drought Severity

Figure 3 depicts the magnitude and extent of drought in 

Texas during the 2011 water year by using data obtained from 

the Drought Monitor (University of Nebraska–Lincoln, 2012) 

from October 1, 2010, to September 20, 2012. On October 1, 

2010, parts of Texas were abnormally dry, but none of Texas 

was classified as being in a drought. By April 2011, nearly 

all of Texas was in a severe to extreme drought, and by the 

end of July 2011, more than 75 percent was in an exceptional 

drought. Figure 3 depicts the widespread extent of drought in 

Texas during the 2011 water year in contrast to water years of 

2010 and 2012 when drought conditions were less prevalent. 

The greatest areal extent of the drought occurred a few days 

after the end of the 2011 water year, around October 4, 2011, 

when 97 percent of Texas was characterized as in an extreme 

to exceptional drought.

Statewide monthly values of the PDSI during the 

droughts of 1951–56 and 2011 are listed in table 4 (U.S. 

Department of Commerce, National Climatic Data Center, 

2012). Between August 1951 and November 1952, 14 of 

16 monthly statewide PDSI values indicated extreme drought 

(PDSI less than -3.99; table 1), and extreme drought also 

occurred during the entire 1955 and 1956 water years. The 

lowest statewide PDSI indicating the most severe drought 

conditions during the period 1951–56 was -7.8, which 

occurred September 1956.

Table 3. Twelve-month statewide average precipitation for 

selected water years in Texas.

[Data source: U.S. Department of Commerce, National Climatic Data Center, 

2012]

Period Precipitation

(inches)

Rank 

(1895–2011)

October 1950–September 1951 18.98 6

October 1951–September 1952 19.88 9

October 1952–September 1953 22.67 20

October 1953–September 1954 19.59 8

October 1954–September 1955 24.89 37

October 1955–September 1956 13.91 2

October 2010–September 2011 11.27 1
8 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

10/1/2010 10/1/2011 9/30/2012

Date

0

20

40

60

80

100

Percentage of State of Texas

affected by drought

Drought severity classification

 D0—Abnormally dry

 D1—Moderate drought

 D2—Severe drought

 D3—Extreme drought

 D4—Exceptional drought

Figure 3. Magnitude and extent of the drought in Texas during October 1, 2010, to September 30, 2012. Data

courtesy of the Drought Monitor (University of Nebraska-Lincoln, 2012). 

EXPLANATION

Figure 3. Magnitude and extent of the drought in Texas during October 1, 

2010, to September 20, 2012. Data courtesy of the Drought Monitor (University 

of Nebraska–Lincoln, 2012).

Table 4. Monthly statewide Palmer Drought Severity Index (PDSI) during the 1951–56 

and 2011 droughts in Texas.

[Data source: U.S. Department of Commerce, National Climatic Data Center, 2012]

Month

Water year

1951 1952 1953 1954 1955 1956 2011

October -0.95 -4.24 -5.75 -2.98 -5.30 -4.31 -0.71

November -1.64 -4.28 -4.46 -2.95 -5.21 -4.55 -1.17

December -2.38 -4.60 -3.70 -2.69 -5.42 -4.82 -1.75

January -2.81 -5.14 -3.88 -2.87 -5.26 -4.90 -1.84

February -3.04 -5.25 -3.71 -3.66 -4.88 -4.76 -2.35

March -2.70 -4.87 -3.55 -4.02 -4.97 -5.01 -3.19

April -3.05 -3.93 -3.17 -3.88 -5.27 -5.19 -4.19

May -3.10 -3.62 -3.05 -3.44 -5.01 -5.72 -5.08

June -3.27 -4.53 -3.86 -4.09 -5.08 -6.54 -6.24

July -3.89 -4.69 -4.02 -4.89 -4.92 -7.05 -7.08

August -4.49 -5.55 -3.29 -5.23 -4.43 -7.30 -7.72

September -4.01 -5.42 -3.74 -5.91 -4.25 -7.80 -7.93

The statewide monthly PDSI declined to -7.93 during 

September 2011, which was larger in magnitude than the PDSI 

values recorded for any drought-affected month during the 

1950s. Also noteworthy is that it only took 12 months from 

the onset of the 2011 drought for the statewide PDSI to drop 

below -7; whereas, it took about 6 years from the onset of 

the 1950s drought until the statewide monthly PDSI values 

dropped below -7.

For a historical perspective, monthly statewide PDSI 

data for the period 1900–2012 are shown in figure 4A. The 

data show both the severity and duration of droughts in Texas. 

Prolonged periods of drought occurred during 1909–11, 

1917–18, 1951–56, and 1963–64. Cleaveland and others 

(2011) used dendrochronology and other methods to evaluate 

drought in several parts of Texas. According to Cleaveland and 

others (2011, p. 54) “this and previous studies indicate that 

severe decadal-scale droughts have occurred in Texas at least 

once a century since the 1500s.” 
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 9

Streamflow

The USGS WaterWatch Web page (U.S. Geological 

Survey, 2012b) displays annual mean runoff, in inches, for 

each State. Annual runoff for Texas during 1901–2011 is 

shown in figure 4B. The lowest 4 years and the respective 

runoff depths are 1917 (0.61 inches), 1918 (0.66 inches), 1956 

(0.71 inches), and 2011 (0.49 inches). These values represent 

annual runoff from gaged basins only. Prior to 1924, fewer 

than 40 streamflow-gaging stations were operated in Texas; 

therefore, statewide runoff computed for those years may not 

be representative of the actual statewide runoff. Comparison 

of figures 4A and 4B shows the effect of drought on runoff. 

Annual statewide values of PDSI were computed as the 

average of the monthly (October to September) PDSI values; 

the relation between the annual PDSI and annual runoff for 

Texas is shown in figure 5. The annual PDSI values for water 

years 1956 and 2011 were -5.66 and -4.10, respectively; 

however, statewide runoff in 2011 was less than during 1956.

Year

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

10

8

6

4

2

0

-2

-4

-6

-8

-10

10

9

8

7

6

5

4

3

2

1

0

Annual runoff, in inches Palmer Drought Severity Index

B

A

Figure 4. A, Monthly Palmer Drought Severity Index for Texas during 1900–2012 (U.S. Department

of Commerce, National Climatic Data Center, 2012) and B, annual runoff for all U.S. Geological Survey

streamflow-gaging stations in Texas during 1901–2011 (U.S. Geological Survey, 2012b). 

Figure 4. A, Monthly Palmer Drought Severity Index for Texas during 1900–2012 (U.S. 

Department of Commerce, National Climatic Data Center, 2012) and B, annual runoff for Texas 

during 1901–2011 (U.S. Geological Survey, 2012b).
10 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

Palmer Drought Severity Index

-8 -4-6 -2 0 2 4 6 8

8

7

6

5

4

3

2

1

0

Annual runoff, in inches

1956

2011

Figure 5. Relation between Palmer Drought Severity Index

(U.S. Department of Commerce, National Climatic Data

Center, 2012) and annual runoff for all U.S. Geological Survey

streamflow-gaging stations in Texas during 1901–2011

(U.S. Geological Survey, 2012b). 

Figure 5. Relation between Palmer Drought Severity 

Index (U.S. Department of Commerce, National Climatic 

Data Center, 2012) and annual runoff for all U.S. 

Geological Survey streamflow-gaging stations in Texas 

during 1901–2011 (U.S. Geological Survey, 2012).

Annual mean streamflow during 1951–56 and 2011 is 

shown in figure 6 for 19 unregulated USGS streamflow‐gaging 

stations (fig. 1, table 2). Also, the mean streamflow for the 

period of record is shown for each station for reference. For 

most of these stations, annual mean streamflow during these 

drought years was well below the mean for the period of 

record. One exception is the Palo Duro gage in the northern 

part of the Texas Panhandle (fig. 1). The annual mean 

streamflow depicted for the Palo Duro gage (07233500, 

fig. 6) is consistent with the finding reported by Nace and 

Pluhowski (1965) that as early as 1953, streamflow in the 

Texas Panhandle region returned to normal. The annual mean 

streamflow for the Palo Duro gage was 0.0 cubic feet per 

second (ft3/s) (zero flow) during 2011, and the daily mean 

streamflow for each day in 2011 also was zero flow. Asquith 

and others (2007) showed an increasing occurrence of zero 

flow for the Palo Duro gage (07233500) for parts of each 

year during 1945–2003, but prior to 2011, an entire year of 

zero flow had never previously been recorded. The mean 

annual streamflow for the Palo Duro gage during 2000–10 

was 3.05 ft3/s. It is not known to what extent the diminishing 

streamflows on Palo Duro Creek are caused by local diversion 

for agriculture or by declining water levels in the High Plains 

aquifer. McGuire (2011) indicates that between about 1950 

and 2007, water levels in the High Plains aquifer declined by 

50 to 100 feet in the northern part of the Texas Panhandle near 

Palo Duro Creek.

Other USGS streamflow-gaging stations for which the 

annual mean streamflow was lower in 2011 than for any year 

during 1951–56 include 07343000 North Sulphur River near 

Cooper, Tex., 07346070 Little Cypress Creek near Jefferson, 

Tex., 08041500 Village Creek near Kountze, Tex., 08070000 

East Fork San Jacinto River near Cleveland, Tex., 08070500 

Caney Creek near Splendora, Tex., 08134000 North Concho 

River near Carlsbad, Tex., and 08205500 Frio River near 

Derby, Tex.; many of these stations are located in eastern 

Texas. Upstream from Derby, Tex., in the upper Frio River 

Basin, annual mean streamflows for USGS streamflow-gaging 

stations 08195000 Frio River at Concan, Tex., and 08198000 

Sabinal River near Sabinal, Tex., were lower in 1956 than in 

2011. Annual mean streamflows for stations in the Guadalupe 

River Basin (08167500 Guadalupe River near Spring Branch, 

Tex.) and Blanco River Basin (08171000 Blanco River at 

Wimberley, Tex.) also were lower in 1956 than in 2011.

Streamflow-duration curves showing the percentage of 

time that a given streamflow was equaled or exceeded during 

1956 and 2011 at 19 unregulated USGS streamflow-gaging 

stations are shown in figure 7. Additionally, streamflow 

duration for the period of record is shown in figure 7 for 

reference. For sites that occasionally go to zero flow, curves 

were extended to approximate the location of 0.1 ft3/s, the 

minimum flow plotted for the logarithmic scale. At stations 

07346070 Little Cypress Creek near Jefferson, Tex., 08041500 

Village Creek near Kountze, Tex., 08070000 East Fork San 

Jacinto River near Cleveland, Tex., and 08070500 Caney 

Creek near Splendora, Tex., streamflows during 2011 were 

lower than for any year during 1951–56 for all computed 

exceedance percentages. For many of the streamflow-gaging 

stations, the 2011 streamflow-duration curves lack the 

typical upward bend near the 5- and 10-percent exceedance 

percentages found in years with near-normal amounts of 

precipitation; the patterns of the streamflow-duration curves 

in figure 7 are consistent with a lack of storm runoff during 

2011. The right-hand side of the curves represents lower 

streamflows typically maintained by inflows of local nearsurface groundwater. 
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 11

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

1951

19521953

1954

19551956

2011

Water year

1951

19521953

1954

19551956

2011

Water year

0

100

200

300

400

500

0

10

20

30

40

50

0

5

10

15

20

25

30

0

25

50

75

100

125

150

0

10

20

30

40

50

Annual mean streamflow, in cubic feet per second

0

100

200

300

400

500

0

100

200

300

400

500

0

20

40

60

80

0

100

200

300

400

0

20

40

60

80

0

200

400

600

800

1,000

1,200

0

40

80

120

160

0

50

100

150

200

250

0

40

80

120

160

0

40

80

120

160

0

500

1,000

1,500

2,000

2,500

0

50

100

150

200

250

0

100

200

300

400

0

20

40

60

80

100

120

140

07346070 08041500 

08068500 08070500 08071000 

08134000 

08150000 08164000 

08166000 08171000 08189500 

08195000 

07233500 

08205500 

07343000 

08070000 

08148500 

08167500 

08198000 

No flow

(0.67)

Annual mean streamflow—

 Value, too small to see as

 a bar, shown in parenthesis

Mean streamflow for period

 of record

U.S. Geological Survey 

 streamflow-gaging

 station number—Table 2 

EXPLANATION

08205500

Figure 6. Annual mean streamflow at selected unregulated U.S. Geological Survey streamflow-gaging stations

in Texas during 1951–56 and 2011. 

Figure 6. Annual mean streamflow at selected unregulated U.S. Geological Survey streamflow-gaging 

stations in Texas during 1951–56 and 2011.
12 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100

Percentage of time the indicated value was equaled or exceeded

Percentage of time the indicated

value was equaled or exceeded

Daily mean streamflow, in cubic feet per second (ft3/s)

0.1

1

10

100

10

100

1,000

10,000

1

10

100

1,000

0.1

1

10

100

1,000

1

10

100

0.1

1

10

100

1,000

0.1

1

10

100

1,000

0.1

1

10

100

1,000

10,000

1

10

100

1,000

10,000

1

10

100

1,000

1

10

100

1,000

0.1

1

10

100

1,000

10,000

0.1

1

10

100

1,000

0.1

1

10

100

1,000

0.1

1

10

100

1,000

10,000

1

10

100

1,000

10,000

0.1

1

10

100

1,000

0.1

1

10

100

1,000

10,000

1

10

100

1,000

No flow at streamflow-gaging

station during 2011

 water year

07233500

08041500

08070500

08148500

07343000 07346070

08068500 08070000

08071000 08134000

08150000 08164000

08166000 08167500 08171000

08189500 08195000

08198000 08205500

Daily mean streamflow—Point

 represents value equaled or

 exceeded 5, 10, 25, 50, 75, 90,

 or 95 percent of the time. 

 Dash indicates approximate

 extension to zero-flow value

 based on an interpolated

 location of 0.1 ft3

/s, the

 minimum flow plotted for

 the logarithmic scale

 1956 water year

 2011 water year

 Period of record

U.S. Geological Survey 

 streamflow-gaging

 station number—Table 2 

EXPLANATION

08205500

Figure 7. Streamflow duration for selected unregulated U.S. Geological Survey streamflow-gaging stations

in Texas for water years 1956, 2011, and the period of record. 

Figure 7. Streamflow duration for selected unregulated U.S. Geological Survey streamflow-gaging 

stations in Texas for 1956, 2011, and the period of record.
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 13

Comparing the low flows of the 1951–56 and 2011 

droughts from a historical perspective by considering data 

from the periods of record at individual streamflow-gaging 

stations is informative. For example, streamflows at station 

07233500 Palo Duro Creek near Spearman, Tex., were 

frequently higher during 1951–55 than for the period of record 

(fig. 6). Low flows at station 07346070 Little Cypress Creek 

near Jefferson, Tex., during 1953 were higher than for the 

period of record. At station 08166000 Johnson Creek near 

Ingram, Tex., a lack of storm runoff during 2011 is apparent, 

but for median and lower streamflows, streamflows in 2011 

were greater than those for the period of record (fig. 7). 

Streamflows exceeded 90 or 95 percent of the time were 

lower for water year 1956 than for water year 2011 at stations 

08068500 Spring Creek near Spring, Tex., 08071000 Peach 

Creek at Splendora, Tex., 8150000 Llano River near Junction, 

Tex., 08164000 Lavaca River near Edna, Tex., 08166000 

Johnson Creek near Ingram, Tex., 08167500 Guadalupe 

River near Spring Branch, Tex., and 08171000 Blanco River 

at Wimberley, Tex. (fig. 7). For most of these stations, the 

minimum of the low streamflows during 1951–56 occurred in 

1956 (fig. 6). 

The USGS WaterWatch Web page (U.S. Geological 

Survey, 2012b) displays current and recent streamflow 

conditions with respect to daily streamflow duration. The 

effects of the 2011 drought on streamflow for 19 unregulated 

USGS streamflow-gaging stations (table 2) are shown in 

figures 8–26. Parts of the 2010 and 2012 water years are 

included for comparison to 2011. Station 07233500 Palo 

Duro Creek near Spearman, Tex., was dry throughout 2011, 

but recorded storm runoff during 2010 and 2012 (fig. 8). 

Streamflow at station 07343000 North Sulphur River near 

Cooper, Tex., was below normal (for this section of this 

report, normal indicates daily streamflow between the 

25th and 75th percentile of recorded streamflows) during 

parts of March and April 2011, and during July through 

September 2011 (fig. 9). Streamflow at station 07346070 Little 

Cypress Creek near Jefferson, Tex., was well below normal 

from February through September 2011 (fig. 10). During 

March to September 2011, record daily lows were measured 

at USGS streamflow‐gaging station 08041500 Village Creek 

near Kountze, Tex., which has more than 70 years of record 

(fig. 11), and station 08070000 East Fork San Jacinto River 

near Cleveland, Tex., was at or near record daily lows during 

March to September 2011 (fig. 13).

 Many USGS streamflow-gaging stations in Texas 

started the 2011 water year with normal streamflow but by 

the end of the 2011 water year were flowing at near-record 

lows. Streamflows at USGS streamflow-gaging station 

08068500 Spring Creek near Spring, Tex., were below normal 

during February through June 2011, but normal during July 

through September 2011 (fig. 12). Stations 08070500 Caney 

Creek near Splendora, Tex., and 08071000 Peach Creek 

near Splendora, Tex., (figs. 14 and 15, respectively) were at 

or near record daily lows during May to September 2011. 

Station 08134000 North Concho River near Carlsbad, Tex., 

frequently goes dry during summer months; streamflows 

on the North Concho River were at or below normal during 

all of 2011, except for a brief period of storm runoff in 

August 2011 (fig. 16). Streamflows at stations 08148500 

North Llano River near Junction, Tex., and 08150000 Llano 

River near Junction, Tex., (figs. 17 and 18, respectively) 

were near normal during October 2010 to February 2011, but 

below normal during March to September 2011. Streamflows 

at station 08166000 Johnson Creek near Ingram, Tex., were 

near normal during the 2011 water year (fig. 20). Stations 

08164000 Lavaca River near Edna, Tex., (fig. 19) and 

08189500 Mission River at Refugio, Tex. (fig. 23), recorded 

storm runoff during January 2011 but by September 2011 

were flowing at near‐record lows. Streamflows at stations 

08167500 Guadalupe River near Spring Branch, Tex., and 

08171000 Blanco River near Wimberley, Tex., (figs. 21 and 

22, respectively) were at or near normal from October 2010 

through February 2011, but then remained below normal 

through September 2011. Streamflows at stations 08195000 

Frio River at Concan, Tex., and 08198000 Sabinal River near 

Sabinal, Tex., (figs. 24 and 25, respectively) fell below normal 

in October 2010, and remained there through September 2011. 

Station 08205500 Frio River near Derby, Tex., which typically 

records zero flow about 30 percent of the time, recorded zero 

flow for 9 months during the 2011 water year (fig. 26).
14 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

20,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 8. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 07233500 Palo Duro Creek near Spearman, Texas (modified

from U.S. Geological Survey, 2012b).

Figure 8. Streamflow duration and daily mean streamflow during January 2010 to September 2012 

for U.S. Geological Survey streamflow-gaging station 07233500 Palo Duro Creek near Spearman, Texas

(modified from U.S. Geological Survey, 2012b). 

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

50,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 9. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 07343000 North Sulphur River near Cooper, Texas (modified 

from U.S. Geological Survey, 2012b). 

Figure 9. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 07343000 North Sulphur River near Cooper, Texas (modified 

from U.S. Geological Survey, 2012b).
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 15

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

40,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 10. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 07346070 Little Cypress Creek near Jefferson, Texas (modified 

from U.S. Geological Survey, 2012b). 

Figure 10. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 07346070 Little Cypress Creek near Jefferson, Texas (modified 

from U.S. Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

10

100

1,000

10,000

70,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 11. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08041500 Village Creek near Kountze, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 11. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08041500 Village Creek near Kountze, Texas (modified from U.S. 

Geological Survey, 2012b).
16 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

10

100

1,000

10,000

60,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 12. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08068500 Spring Creek near Spring, Texas (modified 

from U.S. Geological Survey, 2012b). 

Figure 12. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08068500 Spring Creek near Spring, Texas (modified from U.S. 

Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

10

100

1,000

10,000

50,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 13. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08070000 East Fork San Jacinto River near Cleveland, Texas 

(modified from U.S. Geological Survey, 2012b). 

Figure 13. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08070000 East Fork San Jacinto River near Cleveland, Texas

(modified from U.S. Geological Survey, 2012b).
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 17

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

10

100

1,000

10,000

20,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 14. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08070500 Caney Creek near Splendora, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 14. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08070500 Caney Creek near Splendora, Texas (modified from 

U.S. Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

10

100

1,000

10,000

20,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 15. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08071000 Peach Creek at Splendora, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 15. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for 

U.S. Geological Survey streamflow-gaging station 08071000 Peach Creek at Splendora, Texas (modified 

from U.S. Geological Survey, 2012b).
18 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

70,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 16. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08134000 North Concho River near Carlsbad, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 16. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08134000 North Concho River near Carlsbad, Texas (modified 

from U.S. Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

50,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 17. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08148500 North Llano River near Junction, Texas (modified 

from U.S. Geological Survey, 2012b). 

Figure 17. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08148500 North Llano River near Junction, Texas (modified from 

U.S. Geological Survey, 2012b).
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 19

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

10

1

100

1,000

10,000

100,000

200,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 18. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08150000 Llano River near Junction, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 18. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08150000 Llano River near Junction, Texas (modified from U.S. 

Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

10

1

0.1

100

1,000

10,000

100,000

200,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 19. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08164000 Lavaca River near Edna, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 19. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08164000 Lavaca River near Edna, Texas (modified from U.S. 

Geological Survey, 2012b).
20 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

0.1

10

100

1,000

10,000

20,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 20. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08166000 Johnson Creek near Ingram, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 20. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08166000 Johnson Creek near Ingram, Texas (modified from 

U.S. Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

80,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 21. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08167500 Guadalupe River near Spring Branch, Texas 

(modified from U.S. Geological Survey, 2012b). 

Figure 21. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08167500 Guadalupe River near Spring Branch, Texas (modified 

from U.S. Geological Survey, 2012b).
Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 21

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

40,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 22. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08171000 Blanco River at Wimberley, Texas (modified 

from U.S. Geological Survey, 2012b). 

Figure 22. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for 

U.S. Geological Survey streamflow-gaging station 08171000 Blanco River at Wimberley, Texas (modified 

from U.S. Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

70,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 23. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08189500 Mission River at Refugio, Texas (modified from

U.S. Geological Survey, 2012b). 

Figure 23. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08189500 Mission River at Refugio, Texas (modified from U.S. 

Geological Survey, 2012b).
22 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

0.1

1

10

100

1,000

10,000

60,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 24. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08195000 Frio River at Concan, Texas (modified from

U.S. Geological Survey, 2012b). 

Figure 24. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for 

U.S. Geological Survey streamflow-gaging station 08195000 Frio River at Concan, Texas (modified from U.S. 

Geological Survey, 2012b).

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

1

0.1

10

100

1,000

10,000

20,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 25. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08198000 Sabinal River near Sabinal, Texas (modified

from U.S. Geological Survey, 2012b). 

Figure 25. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08198000 Sabinal River near Sabinal, Texas (modified from U.S. 

Geological Survey, 2012b).
Summary 23

2011 water year

(October 1, 2010–September 30, 2011)

2010 2011 2012

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Daily mean streamflow, in cubic feet per second

10

1

0.1

100

1,000

10,000

100,000

200,000

EXPLANATION

Percentile class, for 

 period of record 

 Greater than 90 to 100 

 Greater than 75 to 90 

 25 to 75 

 10 to less than 25 

 0 to less than 10 

Daily mean streamflow

Figure 26. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for

U.S. Geological Survey streamflow-gaging station 08205500 Frio River near Derby, Texas (modified

from U.S. Geological Survey, 2012b). 

Figue 26. Streamflow duration and daily mean streamflow during January 2010 to September 2012 for U.S. 

Geological Survey streamflow-gaging station 08205500 Frio River near Derby, Texas (modified from U.S. 

Geological Survey, 2012b).

Summary

The intense drought that occurred throughout Texas 

during 2011 resulted in large precipitation deficits throughout 

the State, large drought severity indexes (Drought Monitor 

and Palmer Drought Severity Indexes), and substantial 

declines in streamflow. A record low statewide average annual 

precipitation of 11.27 inches for the period 1895–2011 was 

recorded during the 2011 water year; the prior record low 

statewide average precipitation was 13.91 inches during the 

1956 water year. The statewide average annual precipitation 

during each of the years 1951–56 was less than the normal 

statewide average annual precipitation of 27.95 inches. 

The historical drought of 1951–56 has long been used by 

water-resource managers, engineers, and scientists as a 

point of reference for water‐supply planning. A comparison 

of the 2011 drought to the drought of 1951–56 provides an 

additional reference for water-supply planning. In 2012, the 

U.S. Geological Survey (USGS), in cooperation with the 

Texas Water Development Board, assessed the effects of the 

1951–56 and 2011 droughts from a hydrologic perspective. 

Between August 1951 and November 1952, 14 of 16 monthly 

Palmer Drought Severity Index (PDSI) values indicated 

extreme drought. The 2011 water year began October 1, 

2010, with parts of Texas being abnormally dry, but none of 

Texas was classified as in drought, according to data from the 

Drought Monitor. By April 2011, nearly all of the State was 

experiencing severe to extreme drought, and by the end of 

July 2011, more than 75 percent of the State was experiencing 

exceptional drought. Statewide PDSI values also indicated 

extreme drought during the entire 1955 and 1956 water years. 

The lowest statewide PDSI during the period 1951–56 was 

-7.8, occurring September 1956. The statewide monthly PDSI 

declined to -7.93 during September 2011 and was larger in 

magnitude (larger negative value) than the monthly PDSI for 

any drought-affected month during the 1950s.

Annual mean streamflow during 1951–56 and 2011 

was assessed for 19 unregulated USGS streamflow-gaging 

stations. For most of these sites, annual mean streamflows 

were well below the mean for the period of record. At eight of 

these streamflow-gaging stations, the annual mean streamflow 

was lower in 2011 than for any year during 1951–56; many 

of these stations are located in eastern Texas. Annual mean 

streamflow for streamflow-gaging stations in the Guadalupe, 

Blanco, and upper Frio River Basins were lower in 1956 than 

in 2011.

Streamflow-duration curves for 1956, 2011, and the 

period of record for the 19 unregulated USGS streamflowgaging stations show streamflows exceeded 90 to 95 percent 

of days were lower during 2011 than during 1956 at seven 

of the streamflow-gaging stations. The streamflow-duration 

curves for many streamflow-gaging stations indicate a lack of 

(or diminished) storm runoff during 2011. During March to 

September 2011, record daily lows were measured at USGS 

streamflow-gaging station 08041500 Village Creek near 

Kountze, Tex., which has more than 70 years of record. Many 

other USGS streamflow-gaging stations in Texas started the 

2011 water year (October 1, 2010) with normal streamflow 

but by the end of the 2011 water year (September 2011) were 

flowing at near-record lows.
24 A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011

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Lafayette and Tacoma Publishing Service Centers

Information regarding water resources in Texas is available at

http://tx.usgs.gov/
Winters— A Historical Perspective on Precipitation, Drought Severity, and Streamflow in Texas during 1951–56 and 2011 —Scientific Investigations Report 2013–5113