U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5104

Prepared in cooperation with the Oklahoma Water Resources Board

Trends in Base Flow, Total Flow, and Base-Flow Index of 

Selected Streams in and near Oklahoma through 2008
Cover: This is a downstream photograph of the streamflow-gaging station at North Fork Red River near Carter, Oklahoma, and was 

taken by Martin Schneider, U.S. Geological Survey. 
Trends in Base Flow, Total Flow, and BaseFlow Index of Selected Streams in and near 

Oklahoma through 2008

By Rachel A. Esralew and Jason M. Lewis

Prepared in cooperation with the Oklahoma Water Resources Board

Scientific Investigations Report 2010–5104

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: 2010

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

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

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1-888-ASK-USGS

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.

Suggested citation:

Esralew, R.A., and Lewis, J.M., 2010, Trends in base flow, total flow, and base-flow index of selected streams in and 

near Oklahoma through 2008: U.S. Geological Survey Scientific Investigations Report 2010–5104, 143 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Selection of Data for Analysis .....................................................................................................................3

Streamflow-Gaging Stations ..............................................................................................................3

Precipitation Data ................................................................................................................................8

Streamflow Data ..................................................................................................................................8

Groundwater-Level Data .....................................................................................................................8

Methods of Analysis......................................................................................................................................9

Computation of Base-flow volume and Base-Flow Index..............................................................9

Graphical Analysis and LOESS Trend Lines ...................................................................................10

Kendall’s Tau Test................................................................................................................................10

Kendall’s Tau Test for Streamflow Volume Adjusted for Annual Precipitation.........................12

Trends in Base Flow, Total Flow, and Base-Flow Index.........................................................................15

Precipitation Trend Analysis .............................................................................................................15

Streamflow Volume and Base-Flow Index Trend Analysis..........................................................18

Spatial Patterns in Results for Entire Study Area.................................................................25

Base Flow...........................................................................................................................25

Total Flow ...........................................................................................................................25

Base-Flow index ...............................................................................................................27

Results by Major Drainage Basin ...........................................................................................27

Red Headwaters ...............................................................................................................27

Red-Washita ......................................................................................................................29

Upper Cimarron.................................................................................................................33

Lower Cimarron.................................................................................................................33

North Canadian .................................................................................................................33

Lower Canadian ................................................................................................................34

Arkansas-Keystone ..........................................................................................................34

Neosho-Verdigris..............................................................................................................35

Lower Arkansas ................................................................................................................35

Red-Sulphur.......................................................................................................................35

Annual Peak Flow Trend Analysis....................................................................................................36

Number of Extreme Low-Flow Days Trend Analysis.....................................................................36

Groundwater Level Trend Analysis...........................................................................................................41

Evaluation of Potential Causes of Trends ................................................................................................45

Precipitation Trends ...........................................................................................................................45

Trends Adjusted for Annual or Seasonal Precipitation................................................................46

Groundwater-Level Trends ...............................................................................................................46

Water-Use and Water-Management Practices.............................................................................47

Summary........................................................................................................................................................51

Acknowledgments..............................................................................................................................53

References Cited..........................................................................................................................................53
iv

Figures ...........................................................................................................................................................55

7–47. Graphs showing:

 7. Annual precipitation and LOESS trend lines fro Kansas Climate Divisions 7–9 and 

Oklahoma Climate Division 1, water years 1896–2008. ................................................57

 8. Annual precipitation and LOESS trend lines for Oklahoma Climate Divisions 2–5, 

water years 1896–2008.. ....................................................................................................58

 9. Annual precipitation and LOESS trend lines for Oklahoma Climate Divisions 6–9, 

water years 1896–2008.. ....................................................................................................59

 11. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Arkansas River at Arkansas City, Kansas, (U.S. 

Geological Survey station identifier 07146500, station 1 from table 1), water 

years 1943–2008. ................................................................................................................60

 12. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Salt Fork Arkansas River at Tonkawa, Oklahoma, 

(U.S. Geological Survey station identifier 07151000, station 2 from table 1), water 

years 1942–2008. ................................................................................................................61

 13. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Chikaskia River near Blackwell, Oklahoma, (U.S. 

Geological Survey station identifier 07152000, station 3 from table 1), water 

years 1937–2008. ................................................................................................................62

 14. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Arkansas River at Ralston, Oklahoma, (U.S. 

Geological Survey station identifier 07152500, station 4 from table 1), water 

years 1977–2008. ................................................................................................................63

 15. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Black Bear Creek at Pawnee, Oklahoma, (U.S. 

Geological Survey station identifier 07153000, station 5 from table 1), water 

years 1968–2008. ................................................................................................................64

 16. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Cimarron River near Kenton, Oklahoma, (U.S. 

Geological Survey station identifier 07154500, station 6 from table 1), water 

years 1951–2008. ................................................................................................................65

 17. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Cimarron River near Forgan, Oklahoma, (U.S. 

Geological Survey station identifier 07156900, station 7 from table 1), water 

years 1966–2008. ................................................................................................................66

 18. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Cimarron River near Waynoka, Oklahoma, (U.S. 

Geological Survey station identifier 07158000, station 8 from table 1), water 

years 1938–2008. ................................................................................................................67

 19. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Cimarron River near Dover, Oklahoma, (U.S. 

Geological Survey station identifier 07159100, station 9 from table 1), water 

years 1974–2008. ................................................................................................................68

 20. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Cimarron River near Ripley, Oklahoma, (U.S. 

Geological Survey station identifier 07161450, station 10 from table 1), water 

years 1940–2008. ................................................................................................................69

 21. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Verdigris River near Lenapah, Oklahoma, (U.S. 

Geological Survey station identifier 07171000, station 11 from table 1), water 
v

years 1967–2008. ................................................................................................................70

22. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Caney River near Elgin, Oklahoma, (U.S. Geological 

Survey station identifier 07172000, station 12 from table 1), water years 

1965–2008. ...........................................................................................................................71

23. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Spring River near Quapaw, Oklahoma, (U.S. 

Geological Survey station identifier 07188000, station 13 from table 1), water 

years 1940–2008. ................................................................................................................72

24. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Big Cabin Creek near Big Cabin, Oklahoma, (U.S. 

Geological Survey station identifier 07191000, station 14 from table 1), water 

years 1948–2008. ................................................................................................................73

25. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Spavinaw Creek near Sycamore, Oklahoma, (U.S. 

Geological Survey station identifier 07191220, station 15 from table 1), water 

years 1962–2008. ................................................................................................................74

26. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Illinois River near Tahlequah, Oklahoma, (U.S. 

Geological Survey station identifier 07196500, station 16 from table 1), water 

years 1936–2008. ................................................................................................................75

27. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Baron Fork at Eldon, Oklahoma, (U.S. Geological 

Survey station identifier 07197000, station 17 from table 1), water years 

1949–2008. ...........................................................................................................................76

28. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Canadian River at Bridgeport, Oklahoma, (U.S. 

Geological Survey station identifier 07228500, station 18 from table 1), water 

years 1970–2008. ................................................................................................................77

29. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Little River near Sasakwa, Oklahoma, (U.S. 

Geological Survey station identifier 07231000, station 19 from table 1), water 

years 1966–2008. ................................................................................................................78

30. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Canadian River at Calvin, Oklahoma, (U.S. 

Geological Survey station identifier 07231500, station 20 from table 1), water 

years 1965–2008. ................................................................................................................79

31. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Beaver River at Beaver, Oklahoma, (U.S. Geological 

Survey station identifier 07234000, station 21 from table 1), water years 

1938–2008. ...........................................................................................................................80

32. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for North Canadian River at Sailing, Oklahoma, (U.S. 

Geological Survey station identifier 07238000, station 22 from table 1), water 

years 1947–2008. ................................................................................................................81

33. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for North Canadian River near Wetumka, Oklahoma, 

(U.S. Geological Survey station identifier 07242000, station 23 from table 1), 

water years 1938–2008......................................................................................................82

34. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Deep Fork near Beggs, Oklahoma, (U.S. Geological 
vi

Survey station identifier 07243500, station 24 from table 1), water years 

1968–2008. ...........................................................................................................................83

35. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Fourche Maline near Red Oak, Oklahoma, (U.S. 

Geological Survey station identifier 07247500, station 25 from table 1), water 

years 1966–2008. ................................................................................................................84

36. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Salt Fork Red River at Mangum, Oklahoma, (U.S. 

Geological Survey station identifier 07300500, station 26 from table 1), water 

years 1938–2008. ................................................................................................................85

37. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for North Fork Red River near Carter, Oklahoma, (U.S. 

Geological Survey station identifier 07301500, station 27 from table 1), water 

years 1938–2008. ................................................................................................................86

38. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Deep Red Creek near Randlett, Oklahoma, (U.S. 

Geological Survey station identifier 07311500, station 28 from table 1), water 

years 1970–2008. ................................................................................................................87

39. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Mud Creek near Courtney, Oklahoma, (U.S. 

Geological Survey station identifier 07315700, station 29 from table 1), water 

years 1961–2008. ................................................................................................................88

40. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Red River near Gainesville, Texas, (U.S. Geological 

Survey station identifier 07316000, station 30 from table 1), water years 

1945–2008. ...........................................................................................................................89

41. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Washita River near Cheyenne, Oklahoma, (U.S. 

Geological Survey station identifier 07316500, station 31 from table 1), water 

years 1961–2008. ................................................................................................................90

42. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Washita River near Anadarko, Oklahoma, (U.S. 

Geological Survey station identifier 07326500, station 32 from table 1), water 

years 1964–2008. ................................................................................................................91

43. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Washita River near Dickson, Oklahoma, (U.S. 

Geological Survey station identifier 07331000, station 33 from table 1), water 

years 1962–2008. ................................................................................................................92

44. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Blue River near Blue, Oklahoma, (U.S. Geological 

Survey station identifier 07332500, station 34 from table 1), water years 

1937–2008. ...........................................................................................................................93

45. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Kiamichi River near Big Cedar, Oklahoma, (U.S. 

Geological Survey station identifier 07335700, station 35 from table 1), water 

years 1966–2008. ................................................................................................................94

46. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, 

and LOESS trend lines for Kiamichi River near Antlers, Oklahoma, (U.S. 

Geological Survey station identifier 07336200, station 36 from table 1), water 

years 1984–2008. ................................................................................................................95

47. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and 

LOESS trend lines for Glover River near Glover, Oklahoma, (U.S. 

Geological Survey station identifier 07337900, station 37 from table 1), water 
vii

years 1962–2008. ................................................................................................................96

48–62. Maps showing:

48. Results of Kendall’s tau trend analyses of annual base-flow volume at selected 

streamflow-gaging stations in and near Oklahoma.....................................................97

49. Results of Kendall’s tau trend analyses of annual precipitation-adjusted baseflow volume at selected streamflow-gaging stations in and near Oklahoma. ........98

50. Results of Kendall’s tau trend analyses of winter-spring base-flow volume at 

selected streamflow-gaging stations in and near Oklahoma. ...................................99

51. Results of Kendall’s tau trend analyses of winter-spring precipitation-adjusted 

base-flow volume at selected streamflow-gaging stations in and 

near Oklahoma. ................................................................................................................100

52. Results of Kendall’s tau trend analyses of summer-autumn base-flow volume 

at selected streamflow-gaging stations in and near Oklahoma..............................101

53. Results of Kendall’s tau trend analyses of summer-autumn precipitationadjusted base-flow volume at selected streamflow-gaging stations in and near 

Oklahoma. .........................................................................................................................102

54. Results of Kendall’s tau trend analyses of annual total-flow volume at selected 

streamflow-gaging stations in and near Oklahoma...................................................103

55. Results of Kendall’s tau trend analyses of annual precipitation-adjusted totalflow volume at selected streamflow-gaging stations in and near Oklahoma. ......104

56. Results of Kendall’s tau trend analyses of winter-spring total-flow volume 

at selected streamflow-gaging stations in and near Oklahoma..............................105

57. Results of Kendall’s tau trend analyses of winter-spring precipitation-adjusted 

total-flow volume at selected streamflow-gaging stations in and near 

Oklahoma. .........................................................................................................................106

58. Results of Kendall’s tau trend analyses of summer-autumn total-flow volume 

at selected streamflow-gaging stations in and near Oklahoma..............................107

59. Results of Kendall’s tau trend analyses of summer-autumn precipitationadjusted total-flow volume at selected streamflow-gaging stations in and 

near Oklahoma. ................................................................................................................108

60. Results of Kendall’s tau trend analyses of annual base-flow index at selected 

streamflow-gaging stations in and near Oklahoma...................................................109

61. Results of Kendall’s tau trend analyses of winter-spring base-flow index 

at selected streamflow-gaging stations in and near Oklahoma..............................110

62. Results of Kendall’s tau trend analyses of summer-autumn base-flow index 

at selected streamflow-gaging stations in and near Oklahoma..............................111

65–84. Graphs showing:

65. Number of extreme low-flow days for Chickaskia River near Blackwell, 

Oklahoma, (U.S. Geological Survey station identifier 07152000, station 3 from

 table 1), water years 1937–2008. ..................................................................................112

66. Number of extreme low-flow days for Black Bear Creek at Pawnee, 

Oklahoma, (U.S. Geological Survey station identifier 07153000, station 5 from 

table 1), water years 1968–2008. ...................................................................................113

67. Number of extreme low-flow days for Cimarron River near Kenton, 

Oklahoma, (U.S. Geological Survey station identifier 07154500, station 6 from 

table 1), water years 1951–2008. ...................................................................................114

68. Number of extreme low-flow days for Cimarron River near Waynoka, Oklahoma, 

(U.S. Geological Survey station identifier 07158000, station 8 from 

table 1), water years 1938–2008. ...................................................................................115
viii

69. Number of extreme low-flow days for Caney River near Elgin, Kansas, (U.S. 

Geological Survey station identifier 07172000, station 12 from table 1), water years 

1965–2008. .........................................................................................................................116

70. Number of extreme low-flow days for Big Cabin Creek near Big Cabin, 

Oklahoma, (U.S. Geological Survey station identifier 07191000, station 14 from 

table 1), water years 1948–2008. ...................................................................................117

71. Number of extreme low-flow days for Canadian River at Bridgeport, Oklahoma, 

(U.S. Geological Survey station identifier 07228500, station 18 from table 1),

water years 1970–2008....................................................................................................118

72. Number of extreme low-flow days for Little River near Sasakwa, Oklahoma,

(U.S. Geological Survey station identifier 07231000, station 19 from table 1),

 water years 1966–2008...................................................................................................119

73. Number of extreme low-flow days for Canadian River at Calvin, Oklahoma,

 (U.S. Geological Survey station identifier 07231500, station 20 from table 1), 

water years 1965–2008....................................................................................................120

74. Number of extreme low-flow days for Beaver River at Beaver, Oklahoma, (U.S. 

Geological Survey station identifier 07234000, station 21 from table 1), water 

years 1979–2008. ..............................................................................................................121

75. Number of extreme low-flow days for North Canadian River near Seiling, 

Oklahoma, (U.S. Geological Survey station identifier 07238000, station 22 from 

table 1), water years 1979–2008. ...................................................................................122

76. Number of extreme low-flow days for Fourche Maline near Red Oak, 

Oklahoma, (U.S. Geological Survey station identifier 07247500, station 25 from 

table 1), water years 1966–2008. ...................................................................................123

77. Number of extreme low-flow days for Salt Fork Red River at Mangum , 

Oklahoma, (U.S. Geological Survey station identifier 07300500, station 26 from 

table 1), water years 1938–2008. ...................................................................................124

78. Number of extreme low-flow days for North Fork Red River near Carter , 

Oklahoma, (U.S. Geological Survey station identifier 07301500, station 27 from 

table 1), water years 1938–2008. ...................................................................................125

79. Number of extreme low-flow days for Deep Red Creek near Randlett , 

Oklahoma, (U.S. Geological Survey station identifier 07311500, station 28 from 

table 1), water years 1970–2008. ...................................................................................126

80. Number of extreme low-flow days for Mud Creek near Courtney , Oklahoma, 

(U.S. Geological Survey station identifier 07315700, station 29 from table 1), 

water years 1961–2008....................................................................................................127

81. Number of extreme low-flow days for Washita River near Cheyenne , 

Oklahoma, (U.S. Geological Survey station identifier 07316500, station 31 from 

table 1), water years 1961–2008. ...................................................................................128

82. Number of extreme low-flow days for Kiamichi River near Big Cedar , 

Oklahoma, (U.S. Geological Survey station identifier 07335700, station 35 from 

table 1), water years 1966–2008. ...................................................................................129

83. Number of extreme low-flow days for Kiamichi River near Antlers , Oklahoma, 

(U.S. Geological Survey station identifier 07336200, station 36 from table 1), 

water years 1984–2008....................................................................................................130

84. Number of extreme low-flow days for Glover River near Glover , Oklahoma, 

(U.S. Geological Survey station identifier 07337900, station 37 from table 1), 

water years 1962–2008....................................................................................................131

85–87. Maps showing:

85. Results of Kendall’s tau trend analyses of the annual number of days when 
ix

streamflow is (A) equal to zero cubic feet per second and (B) less than 1 

cubic foot per second for selected streamflow-gaging stations in and near 

Oklahoma. .........................................................................................................................132

 86. Results of Kendall’s tau trend analyses of the number of days per year during 

the period of November through May (winter-spring) when streamflow is (A) 

equal to zero cubic feet per second and (B) less than 1 cubic foot per second 

for selected streamflow-gaging stations in and near Oklahoma. ...........................133

 87. Results of Kendall’s tau trend analyses of the number of days per year during the 

period of June through October (summer-autumn) when streamflow is (A) equal 

to zero cubic feet per second and (B) less than 1 cubic foot per second 

for selected streamflow-gaging stations in and near Oklahoma. ...........................134

88–96. Graphs showing:

 88. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 1–4. .....................................................................................................................135

 89. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 5–8. .....................................................................................................................136

 90. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 9–12. ...................................................................................................................137

 91. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 13–16. .................................................................................................................138

 92. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 17–20. .................................................................................................................139

 93. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 21–24. .................................................................................................................140

 94. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 25–28. .................................................................................................................141

 95. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 29–32. .................................................................................................................142

 96. Groundwater levels and LOESS trend lines by using available periods of record 

for wells 33–35. .................................................................................................................143

Figures

1–2. Maps showing:

 . Location of streamflow-gaging stations used in trends analyses. .............................4

 2. National Weather Service Climate Divisions used in annual and seasonal 

precipitation analysis. .........................................................................................................9

3–6. Graphs showing:

 3. Procedure used to select an optimal partition length (N) for computation of 

base-flow volume by minimizing the slope change between a relation of median 

annual base-flow index and partition length for Blue River near Blue, Oklahoma, 

(USGS Station Identifier 07332500; station 34, table 1). ...............................................11

 4. Base-flow separation during sequential storms for Spring River near Quapaw, 

Oklahoma, (USGS Station Identifier 07188000; station 13, table 1). ...........................12

 5. Relation between annual base-flow volume and annual precipitation at four 

streamflow-gaging stations in Oklahoma. Station numbers are referenced on 

table 1. .................................................................................................................................13
x

6. Trends in base-flow volume at Spavinaw Creek near Sycamore, Oklahoma, 
xi

12. Results of Kendall’s tau trend analyses on the number of extreme low-flow days

for 17 selected streamflow-gaging stations in and near Oklahoma.............................40

13. Results of Kendall’s tau trend analyses of annual winter groundwater levels for

entire period of record in 35 selected ground water wells in Oklahoma.....................42

14. Estimated total freshwater withdrawals in Oklahoma by water-use category, 

1950-2005.................................................................................................................................48

Conversion Factors and Datums

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 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2) 

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3) 28.32 cubic decimeter (dm3) 

cubic foot (ft3) 0.02832 cubic meter (m3) 

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

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

Flow rate

acre-foot per day (acre-ft/d) 0.01427 cubic meter per second (m3/s)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/yr)

acre-foot per year (acre-ft/yr) 0.001233 cubic hectometer per year (hm3/yr)

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

cubic foot per second per square

mile [(ft3/s)/mi2]

 0.01093 cubic meter per second per square

kilometer [(m3/s)/km2]

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

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).

Altitude, as used in this report, refers to distance above the vertical datum.
xii
Abstract 

The U.S. Geological Survey, in cooperation with the 

Oklahoma Water Resources Board, investigated trends in base 

flow, total flow, and base-flow index of selected streams in 

Oklahoma and evaluated possible causes for trends. Thirtyseven streamflow-gaging stations that had unregulated or moderately regulated streamflow were selected for trend analysis.

Statistical evaluation of trends in annual and seasonal 

(winter-spring and summer-autumn) base flow, total flow, and 

base-flow index at 37 selected streamflow-gaging stations in 

Oklahoma was performed by using a Kendall’s tau trend test. 

This trend analysis also was performed for annual and seasonal precipitation for nine climate divisions in the study area, 

annual peak flows, the number of days where flow was zero or 

less than 1 cubic foot per second (both annually and seasonally), and annual winter groundwater levels for 35 shallow 

wells near the analyzed stations. Precipitation-adjusted trends 

using LOESS regressions and Kendall’s tau were computed 

for annual and seasonal base-flow and total-flow volumes in 

order to identify the presence of underlying trends in streamflow that are not associated with annual or seasonal variations 

in precipitation. 

In general, upward trends in precipitation were detected 

for climate divisions in north-central Oklahoma and southcentral and southeastern Kansas. More climate divisions had 

statistically significant upward trends in total precipitation for 

annual water years than in winter-spring or summer-autumn 

water years.

Significant trends in annual or seasonal base-flow volume 

were detected for 22 stations, 19 of which had trends that were 

upward in direction. Significant trends in annual or seasonal 

total-flow volume were detected for 14 stations, 9 of which 

had trends that were upward in direction. Most stations that 

had significant upward trends in annual or seasonal totalflow volume also had significant upward trends in base-flow 

volume for the same period. Precipitation adjustment changed 

the results (significant only or significance and direction) of 

significant annual or seasonal trends in unadjusted base-flow 

volume for 12 stations and in unadjusted total-flow volume for 

13 stations. 

Significant trends in annual or seasonal base-flow index 

were detected for 25 stations, 23 of which had trends that were 

upward in direction. Eighteen stations that had significant 

upward trends in annual or seasonal base-flow index also had 

significant upward trends in base-flow volume and no significant downward trends in total-flow volume during the same 

period, which indicated that upward trends in base-flow index 

were likely driven by increases in base flow at these stations. 

Trend results were highly variable throughout the State. 

However, some recurring patterns in locations of stations with 

similar trend results were detected. In general, significant 

downward trends in base-flow and total-flow volumes were 

detected for the three stations in the Oklahoma Panhandle. 

Significant upward trends in annual or seasonal base-flow volume before and after precipitation adjustment were detected 

for 12 stations in southwestern and central Oklahoma. In eastern Oklahoma, significant upward trends in annual or seasonal 

base-flow volume were only detected for 4 stations, and significant upward trends in annual or seasonal total-flow volume 

were only detected for 1 station. After precipitation adjustment 

no stations in this region had significant upward trends in 

either parameter, one station had significant downward trends 

in annual base-flow volume, and one station had significant 

downward trends in winter-spring total-flow volume.

Increases in annual and seasonal precipitation, especially 

during a substantial wet period (1980-2000), may be one of 

the factors resulting in upward trends in base-flow volume 

and total-flow volume at many of the stations analyzed in this 

report. Eleven stations with significant upward trends in precipitation-adjusted annual and winter-spring base-flow volume 

were located in or near principal aquifers where many wells 

had significant upward trends in groundwater levels. Significant upward trends in annual or seasonal base-flow index were 

detected for all of these stations. Significant upward trends in 

base-flow volume and base-flow index for these stations may 

indicate increased recharge of underlying aquifers as a result 

of increases in precipitation, artificial recharge from irrigation returns, or changes in irrigation practices in the region. 

Downward trends in base-flow volume and total-flow volume 

in the Oklahoma Panhandle likely are caused by long-term 

Trends in Base Flow, Total Flow, and Base-Flow Index of 

Selected Streams in Oklahoma through 2008

By Rachel A. Esralew and Jason M. Lewis
2 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

declines in groundwater levels and surface-water diversions 

for irrigation. 

Introduction

Comprehensive planning for water-resources management, development, and use in Oklahoma can benefit from a 

description of temporal trends in streamflow and how these 

trends might vary throughout the State. Awareness of these 

trends can be useful to water-resources management agencies 

for drought monitoring and planning, water-supply permitting and allocation of beneficial water uses, maintenance of 

adequate streamflows for the protection of aquatic ecosystems, 

wastewater operations, and maintenance of streamflows for 

water-quality management. 

Evidence indicates that the quantity of streamflow may 

be changing in the long-term for some streams in Oklahoma 

as a response to anthropogenic activities as well as changes in 

climate. For example, previous studies demonstrated that base 

flow and peak flow in some streams in the upper Beaver/North 

Canadian River Basin were decreasing as a result of depletion 

of groundwater and changes in land-use practices, especially 

since 1978 (Wahl and Tortorelli, 1997; Tortorelli and others 

2005). In contrast, Smith and Wahl (2003) determined that the 

lower North Fork Red River had significant upward trends in 

base flow. Smith and Wahl (2003) reported that these trends 

may have been caused by changes in irrigation activities near 

the station or in the drainage basin. Previous studies also 

indicated that mean annual streamflow is increasing for many 

streams in Oklahoma, as much as 6.6 percent per year in the 

Washita River Basin, which may be a result of increases in 

precipitation (Tortorelli and others, 2005). 

The most direct potential cause of long-term changes in 

streamflow is a change in precipitation, which is a function of 

variable climate conditions attributed, in part, to increasing 

global temperatures (Crawford and McManus, 2008). Previous studies have indicated that total precipitation in the United 

States has increased 10 percent during the 20th century from 

1910 to 1995, and that during that time there was a statistically significant increase in the number of annual precipitation 

events (Karl and Knight, 1998). The same analysis revealed an 

increase in the intensity of some rainfall events. Oklahoma had 

an unprecedented wet period from the early 1980s to around 

2000 (Oklahoma Water Resources Board, 2006; Garbrecht and 

Schneider, 2007). Increases in total precipitation may cause 

increases in streamflow as expressed by increases in annual 

and seasonal base-flow and total-flow volumes. 

Despite the documented increase in streamflow from 

the early 1980s to 2000 for Oklahoma, precipitation and 

streamflow were highly variable in recent years. Water year 

2006 (October 1, 2005, to September 30, 2006) was a year of 

extreme hydrologic drought and the driest year in the 2002-06 

drought in Oklahoma (Tortorelli, 2009). In contrast with that 

drought, Oklahoma experienced one of the wettest years on 

record in water year 2007 for precipitation and streamflow 

(Arndt, 2007; Blazs and others, 2007). 

Increased water demand as a result of population growth 

and development of agriculture in the State may reduce 

the variability of groundwater and surface-water resources 

through groundwater depletion and surface-water diversions 

for water supply. Depletion of groundwater and surface-water 

resources can reduce the magnitude of streamflow as well as 

extend the duration of periods of extreme low flow and periods of no streamflow, especially during dry years. In contrast, 

increases in groundwater levels and surface-water volumes 

may result from changes in land-management practices 

intended to reduce soil erosion and increase irrigation efficiency, such as no-till farming, micro-irrigation, and centerpivot irrigation (Beck and others, 1998, Luckey and Becker, 

1999, Smith and Wahl, 2003, Tortorelli and others, 2005) 

The rate and degree to which anthropogenic and climatic factors affect streamflow for drainage basins in the 

long-term can vary between drainage basins and across the 

State. Streamflow information collected at streamflow-gaging 

stations in Oklahoma can be used to statistically analyze, identify, and describe temporal trends in base flow and total flow.

Statistical trend analysis can be used to determine the 

probability that an upward or downward trend in streamflow has actually happened, and that a series of increases or 

decreases for any given set of years is not just because of 

random variability. In addition to statistical analysis, plotting results of temporal trends in streamflow can be useful 

in visualizing patterns and direction of trends. For example, 

a plot may show a change in the trend slope after a specific 

date, which statistical trend analysis might not easily convey. 

Mapping of statistical results of temporal trends in streamflow 

can help to reveal regional patterns in upward and downward 

trends across the State. 

A simple observation of changes in base flow may not 

fully describe the complex nature of the streamflow regime 

and the potential response of streamflow to climate variability 

and anthropogenic activities. Analyzing the trend in the ratio 

of base flow to total flow, referred to as the base-flow index, 

can provide information about changes in the proportion of 

total flow that is derived from base flow. For example, if there 

are downward trends in base flow and total flow but an upward 

trend in the base-flow index, this might indicate that runoff is 

being depleted at a faster rate than base flow. Runoff depletion may be a response to a decrease in the frequency of storm 

events or an increase in the rate of direct surface-water withdrawals and diversions or a combination of both factors. This 

example of upward trends in base-flow index with downward 

trends in base-flow and total-flow volumes was observed for 

many stations in the Beaver/North Canadian River Basin from 

1978 to 1994 as reported by Wahl and Tortorelli (1997). 
Selection of Data for Analysis 3

Trend analysis of additional streamflow parameters, such 

as extreme high- and low-flow characteristics, including the 

number of days where extreme low-flow or zero-flow conditions are present, and changes in peak flow also are helpful 

for comprehensive water-resources management, especially 

for flood control, water supply permitting, and wastewater 

management (R.S. Fabian, Oklahoma Water Resources Board, 

written commun., September 2009). In addition, analysis of 

these parameters may help in identification of additional characteristics of the streamflow regime that might be changing 

because of climatic or anthropogenic influences. 

Evaluation of changes in streamflow also can be 

enhanced by an analysis of possible causes of trends. Knowledge of possible causes of trends in streamflow can be useful 

for predicting whether the trend is likely to continue in the 

future. Spatial and temporal trends in annual precipitation 

and groundwater levels and an assessment of historical water 

use can be used to evaluate possible causes of increasing or 

decreasing streamflow. 

The U.S. Geological Survey, in cooperation with the 

Oklahoma Water Resources Board, investigated trends in base 

flow, total flow, and base-flow index at selected streamflowgaging stations in and near Oklahoma on an annual and 

seasonal basis. Also included are evaluation of trends in 

extreme low-flow days and peak flow to provide a comprehensive analysis of streamflow, and trends in precipitation and 

groundwater levels to evaluate potential causes of trends in 

streamflow.

Purpose and Scope

The purpose of this report is to describe trends in base 

flow, total flow, and base-flow index for selected streams 

in and near Oklahoma and to evaluate possible causes for 

observed trends. In addition, trends in annual and seasonal 

precipitation, annual peak flow, the annual and seasonal 

number of days where flow was zero or was less than 1 cubic 

foot per second (ft3/s), and winter groundwater levels were 

assessed. 

This report includes (1) a summary of data selected for 

trend analysis from streamflow-gaging stations with long-term 

streamflow record and the streamflow parameters that were 

analyzed; (2) a summary of the methods used to compute 

base-flow volume and evaluate trends; (3) documentation of 

whether statistically significant trends exist in annual and seasonal base-flow volume, total flow volume, base-flow index, 

annual peak flow, and the number of days where streamflow 

was zero or was less than 1 ft3/s; and (4) an evaluation of possible causes of streamflow trends, including analysis of trends 

in precipitation and in streamflow adjusted for precipitation, 

in groundwater levels, and discussion of historic water-use 

activities and water-management practices that may affect 

observed streamflow trends. 

Selection of Data for Analysis

Streamflow-Gaging Stations 

The primary objectives of this report are to (1) determine 

if statistically significant trends in streamflow were observed 

for streamflow-gaging stations with long-term periods of 

record where base flow and total flow were not substantially 

affected by streamflow regulation (fig. 1) and (2) determine 

if spatial patterns for stations with significant trends were 

observable. Successful regional streamflow trend analysis in 

a large geographic area requires a large number of stations 

with a long period of record (Tortorelli, 2005). An attempt was 

made to select stations with a minimum length of continuous 

daily-mean streamflow record of at least 40 years that had 

streamflow data through water year 2008 without substantial 

record gaps and to select stations that had unregulated periods 

of record. For this report, streamflow at a station was considered regulated if 20 percent or more of the drainage basin 

upstream from the station was upstream from water-supply 

reservoirs or floodwater retarding (FWR) structures, which 

was the criterion for regulation used in previous studies in 

Oklahoma (Tortorelli, 2002; Lewis and Esralew, 2009). 

Only 17 stations in the State met these criteria for unregulated conditions and record length, hence additional stations 

were selected to cover areas of the State that would not have 

been adequately represented. In addition, because so many 

streams in Oklahoma are regulated, inclusion of regulated 

streams in the analysis was needed. However, only the regulated period of record was used in the trend analysis to eliminate the start date of regulation as a possible cause of streamflow trends. For all stations in which streamflow was affected 

by regulation, the year of construction of the flow controlling 

structure that resulted in 20 percent of the drainage-basin area 

of the station being affected by regulation marked the beginning of the regulated period of record. 

Thirty-seven stations were selected for trend analysis. 

Two stations with an unregulated streamflow record of at 

least 34 years were selected. Fourteen stations selected for the 

analysis were regulated by water-supply reservoirs (table 1). 

For these stations, the regulating reservoirs were far upstream 

from the station (40 river miles or greater) or were not on the 

main stem of the river. Therefore, an assumption was made 

that the regulation was moderate, and those stations were considered acceptable for use in the trend analysis. 

Eight stations in which streamflow was regulated by 

floodwater-retarding (FWR) structures also were evaluated 

for this report. Streamflow at four of the eight stations also 
4 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 36

2

16

14

13 11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5025 MILES0 50 KILOMETERS

36°

97°

34°

94° 103° 100°

R iver

Neosho R iver

R iver

R ed

Beaver

R iver

C imarron

R iver

Fork

Salt

R

iver

Arkansa

R iver

s

R iver Verdigris

River

North

Canadian

Canadian

R iver

Washita

Baron

Fork Fork

R ed

R iver

Caney

15

COLORADO

State border

Streamflow gaging station andnumber from table 1

#

14

Streams

Albers Equal-Area Conic Projection.

North American Datum 1983.

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Sulphur

Red

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

Canton Lake

C hikask ia

R iver

Black Bear

C

reek

River

Illinois

Big Cabi n

Creek

Spring

River

River

Little

R iver

Kiamichi

r R ev lo G er iv Blue River

Deep Red

Creek

Deep

Sal t

R

ed

F ork

River

River

North

Fork

R

ed

Mud

Creek

Blue

Beggs

Dover

Eldon

Ripley

Pawnee

Quapaw

Glover

Calvin Mangum

Kenton

Carter

Forgan

Beaver Waynoka

Sasak

Antlers

Ralston

Lenapah

Red Oak

Tonkawa

Wetumka

Seiling

Dickson

Cheyenne

Courtney

Sycamore

Randlett

Anadarko

Big Cedar

Big

Cabin

Tahlequah

Bridgeport

21

22

-wa

Blackwell Arkansas City

Elgin

Gainesville

Town

Red-Washita

EXPLANATION

Location of streamflow-gaging stations used in trends analyses. Figure 1.
Selection of Data for Analysis 

5

Table 1. Summary of streamflow period of record for selected continuous-record streamflow-gaging stations used in study. —Continued [no., number; USGS station ID, U.S. Geological Survey station identifier; nr, near; Ck, Creek; Climate Division, the climate division in which the gage is located, codes are defined in table 2; mi2, square miles; I, irrigation; U, unregulated; R, regulated; dms, degrees, minutes, seconds; WS, water-supply reservoir; FWR, Natural Resources Conservation Service floodwater-retarding structure; WY, water year; --, none]

Station 

no. 

(fig. 1)

USGS 

station 

ID

Station name Climate division Drainage area (mi2) Latitude (dms) Longitude (dms) Type of record Type of regu- lation1 Continu- ous period of record (WY) Was period used for sta- tistical trend analysis?

1 07146500 Arkansas River nr Arkansas City, Kans. KS-8 36,106 370323 0970332 U -- 1922-1942 No

R WS 1943-2008 Yes

2 07151000 Salt Fork Arkansas River at Tonkawa, Okla.2 OK-2 4,520 364019 0971833 U -- 1936-1940 No

R WS 1942-2008 Yes

3 07152000 Chikaskia River nr Blackwell, Okla. OK-2 1,859 364841 0971637 U -- 1937-2008 Yes4 07152500 Arkansas River at Ralston, Okla.2 OK-3 54,465 363015 0964341 U -- 1926-1975 No

R WS 1977-2008 Yes

5 07153000 Black Bear Ck at Pawnee, Okla.2 OK-3 576 362037 0964757 U -- 1945-1962 No

R FWR 1968-2008 Yes

6 07154500 Cimarron River nr Kenton, Okla. OK-1 1,038 365536 1025731 U -- 1951-2008 Yes7 07156900 Cimarron River nr Forgan, Okla.2 KS-7 4,220 370040 1002929 U -- 1966-2008 Yes8 07158000 Cimarron River nr Waynoka, Okla. OK-2 8,504 363102 0985245 U -- 1938-2008 Yes9 07159100 Cimarron River nr Dover, Okla. OK-5 10,787 355706 0975451 U -- 1974-2008 Yes

10 07161450 Cimarron River nr Ripley, Okla.4 OK-5 13,053 355909 0965443 U -- 1940-2008 Yes

11 07171000 Verdigris River nr Lenapah, Okla.2 OK-3 3,639 365104 0953509 U -- 1939-1959 No

R WS 1967-2008 Yes

12 07172000 Caney River nr Elgin, Kans. KS-9 445 370014 0961859 U -- 1940-1964 No

R FWR 1965-2008 Yes
6 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 Table 1. Summary of streamflow period of record for selected continuous-record streamflow-gaging stations used in study. —Continued [no., number; USGS station ID, U.S. Geological Survey station identifier; nr, near; Ck, Creek; Climate Division, the climate division in which the gage is located, codes are defined in table 2; mi2, square miles; I, irrigation; U, unregulated; R, regulated; dms, degrees, minutes, seconds; WS, water-supply reservoir; FWR, Natural Resources Conservation Service floodwater-retarding structure; WY, water year; --, none] Continu- Was period Station USGS Type of Climate Drainage Latitude Longitude Type of ous period used for sta- no. station Station name regu- division area (mi2) (dms) (dms) record of record tistical trend (fig. 1) ID lation1 (WY) analysis? 13 07188000 Spring River nr Quapaw, Okla. OK-3 2,510 365604 0944446 U -- 1940-2008 Yes 14 07191000 Big Cabin Ck. nr Big Cabin, Okla. OK-3 450 363406 0950907 U -- 1948-2008 Yes 15 07191220 Spavinaw Ck. nr Sycamore, Okla. OK-3 133 362007 0943827 U -- 1962-2008 Yes 16 07196500 Illinois River nr Tahlequah, Okla. OK-6 635 360748 0943419 U -- 1936-2008 Yes 17 07197000 Baron Fork at Eldon, Okla. OK-6 304 355516 0945018 U -- 1949-2008 Yes 18 07228500 Canadian River at Bridgeport, Okla.2 OK-7 20,475 353237 0981903 U -- 1945-1964 No R WS 1970-2008 Yes 19 07231000 Little River nr Sasakwa, Okla.2 OK-5 884 345755 0963044 U -- 1943-1961 No R WS/FWR 1966-2008 Yes 20 07231500 Canadian River at Calvin, Okla.5 OK-6 23,151 345840 0961436 U -- 1939-1964 No R WS 1965-2008 Yes 21 07234000 Beaver River at Beaver, Okla. 6 OK-1 3,685 364920 1003108 U -- 1938-1971 No IR WS 1979-2008 Yes 22 07238000 North Canadian River nr Seiling, Okla.7 OK-2 7,414 361100 0985515 U -- 1947-1971 No IR WS 1979-2008 Yes 23 07242000 North Canadian River nr Wetumka, Okla. OK-6 9,391 351556 0961221 R WS 1938-2008 Yes 24 07243500 Deep Fork nr Beggs, Okla. OK-6 2,018 354026 0960406 U -- 1939-1967 No R WS/FWR 1968-2008 Yes 25 07247500 Fourche Maline nr Red Oak, Okla. 2,7 OK-9 122 345445 0950920 U -- 1939-1963 Yes R FWR 1966-2008 No

26 07300500 Salt Fork Red River at Mangum, Okla. OK-7 1,357 345130 0993030 U -- 1938-2008 Yes27 07301500 North Fork Red River nr Carter, Okla.8 OK-4 1,938 351005 0993025 U -- 1938-2008 Yes28 07311500 Deep Red Ck nr Randlett, Okla. OK-7 617 341315 0982710 U -- 1970-2008 Yes29 07315700 Mud Creek nr Courtney, Okla. OK-8 572 340015 0973400 U -- 1961-2008 Yes
Selection of Data for Analysis

7

Table 1. Summary of streamflow period of record for selected continuous-record streamflow-gaging stations used in study. —Continued [no., number; USGS station ID, U.S. Geological Survey station identifier; nr, near; Ck, Creek; Climate Division, the climate division in which the gage is located, codes are defined in table 2; mi2, 

square miles; I, irrigation; U, unregulated; R, regulated; dms, degrees, minutes, seconds; WS, water-supply reservoir; FWR, Natural Resources Conservation Service floodwater-retarding structure; WY, water year; --, none]

Continu- Was period Station USGS Type of Climate Drainage Latitude Longitude Type of ous period used for sta- no. station Station name regu- division area (mi2) (dms) (dms) record of record tistical trend (fig. 1) ID lation1 (WY) analysis?

30 07316000 Red River nr Gainesville, Tex.2 OK-8 24,846 334340 0970935 U -- 1937-1943 No

R 1945-2008 Yes

31 07316500 Washita River nr Cheyenne, Okla. OK-4 794 353735 0994005 U -- 1938-1960 No

R FWR 1961-2008 Yes

32 07326500 Washita River at Anadarko, Okla. OK-7 3,635 350503 0981435 R WS/FWR 1964-2008 Yes33 07331000 Washita River nr Dickson, Okla.2 OK-8 7,202 341400 0965832 U -- 1929-1960 No

R WS/FWR 1962-2008 Yes

34 07332500 Blue River nr Blue, Okla. OK-8 476 335949 0961427 U -- 1937-2008 Yes35 07335700 Kiamichi River nr Big Cedar, Okla. OK-9 40 343818 0943645 U -- 1966-2008 Yes36 07336200 Kiamichi River nr Antlers, Okla.2 OK-9 1,138 341455 0953618 U -- 1973-1982 No

R WS 1984-2008 Yes

37 07337900 Glover River nr Glover, Okla. OK-9 315 340551 0945407 U -- 1962-2008 Yes

1 Streamflow at stations is considered substantially affected by regulation when at least 20 percent of the drainage-area is upstream from water-supply reservoirs or floodwater retarding structures 

(Lewis and Esralew, 2009).

2 Streamflow record period is omitted during transition between unregulated and regulated periods when reservoir (s) under construction.3 Streamflow data not available for water year 19874 Includes streamflow record 1940-89 from nearby station 07161000, Cimarron River at Perkins, Okla.5 Streamflow data not available for water years 1943-19446 Pre- and post-irrigation development as defined in Wahl and Tortorelli (1997). Through water year 1971 is unregulated, water year 1972-78 are transition years to full irrigation development and 

regulated by reservoir.

7 Streamflow data not available for water year 19918 Streamflow data not available for water years 1963-1964
8 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

were regulated by water-supply reservoirs. Many of the FWR 

structures were constructed in the late 1950s and 1960s by 

the Soil Conservation Service, now the Natural Resources 

Conservation Service (NRCS) (Smith and Esralew, 2010). 

With the exception of a few areas in southwestern and eastern 

Oklahoma, most FWR structures are concentrated in floodprone regional areas such as the Washita River Basin (fig. 

1) and north-central Oklahoma (Smith and Esralew, 2009). 

The effects of regulation of streamflow by FWR structures 

on base flow and total flow may be regional because of the 

large number of these structures in Oklahoma. Analysis of 

streamflow data in basins affected by FWR structures gives 

a representation of potential trends for streams in and around 

these regions, and therefore can be useful for water resources 

management in the State. 

An irrigation period of record was defined for stations in 

the Beaver/North Canadian River Basin above Canton Lake 

(fig. 1), which have been substantially affected by irrigation 

development since 1978 as described in Wahl and Tortorelli 

(1997). Stations where the irrigated period previously was 

defined by using trend analysis include the Beaver River near 

Beaver (station 21, fig. 1), and North Canadian River near 

Seiling (station 22, fig. 1). For this report, the more recent 

irrigated period after 1978 was used in the trend analysis for 

consistency in order to reflect the most recent conditions in the 

Beaver/North Canadian River Basin. Streamflow at some other 

stations, including those in the Upper Cimarron Basin River 

(fig. 1), likely has been affected by groundwater development and surface-water withdrawals for irrigation (Lewis and 

Esralew, 2009), but trends have not been previously calculated 

to document the period of record most likely to be affected by 

these activities. The entire period of record for all stations with 

long-term record through water year 2008 in the Upper Cimarron River Basin was included in the trend analysis.

Precipitation Data 

Trends in annual and seasonal precipitation were calculated to evaluate potential sources of streamflow trends caused 

by changes in climate over the study period. Precipitation 

rates and amounts are highly variable temporally and spatially. 

Areal averages likely are better indicators of the amounts of 

precipitation that may appear as runoff at a station than are the 

precipitation amounts measured at individual stations (Tortorelli and others, 2005). Dating back to 1895, monthly and 

annual precipitation data are available for National Weather 

Service Climate Divisions, which summarize areal averages 

of precipitation data collected from individual stations into 

climate divisions (National Oceanic and Atmospheric Administration, 2009). Stations used in this analysis are located in 

nine climate divisions in Oklahoma and three climate divisions 

in southern Kansas (table 1, fig. 2). 

For precipitation, trend analysis was done by analyses 

of data from annual and seasonal water years. An annual 

water year is defined as the 12-month period of October 1 

through September 30. Seasonal water years are divided into 

winter-spring months and summer-autumn months to correlate to regulatory periods of the Oklahoma Water Resources 

Board. For this report, a winter-spring water year is defined 

as the 6-month period of November 1 through May 30, and a 

summer-autumn water year is defined as the 6-month period of 

June 1 to October 30. The winter-spring and summer-autumn 

water years are designated by the annual water year for which 

the seasonal water year starts. For example, a winter-spring 

water year starting in November of 2007 and a summerautumn water year starting in June of 2008 would be designated as winter-spring water year 2008 and summer-autumn 

water year 2008, respectively. 

For purposes of this report, all annual and seasonal analysis periods are defined by the water years used for analysis 

followed by the streamflow parameter. For example, annual 

precipitation computed for the entire annual water year is 

referred to as “annual precipitation”; whereas, seasonal precipitation computed for just winter-spring or summer-autumn 

water years is referred to as “winter-spring precipitation” and 

“summer-autumn precipitation”, respectively.

Streamflow Data 

Trends were calculated for annual and seasonal time 

periods for base-flow and total-flow volumes, base-flow index, 

and the number of days with streamflow less than 1 ft3/s and 

days with streamflow equal to zero ft3/s. For purposes of this 

report, the number of days with streamflow less than 1 ft3/s 

and days with streamflow equal to zero ft3/s also are referred 

to as “extreme low-flow days”. Trends also were calculated for 

annual instantaneous peak flow trends only for annual water 

years.

For this report, notation for annual and seasonal streamflow is similar to the notation for precipitation. For example, 

annual base-flow volume computed for an entire water year 

is referred to as “annual base-flow volume”; whereas, annual 

base-flow volume analyzed for just winter-spring or summerautumn water years is referred to as “winter-spring base-flow 

volume” and “summer-autumn base-flow volume”, respectively. Base-flow and total-flow volumes, base-flow index, and 

the number of extreme low-flow days were computed only for 

annual and seasonal water years that had complete water years 

of record in the analysis periods from table 1. Annual instantaneous peak flow values were only analyzed for periods with 

continuous daily mean streamflow record selected for analysis 

(table 1).

Groundwater-Level Data

Trends in winter groundwater levels were calculated to 

evaluate potential sources of streamflow trends arising from 

changes in groundwater storage and local and regional groundwater use for irrigation and public supply. Trends in winter 

groundwater levels were calculated for 35 wells in Oklahoma. 
Methods of Analysis 9

Data from 33 wells were obtained from the Oklahoma Water 

Resources Board annual mass measurement program (Oklahoma Water Resources Board, 2008). Data from 2 wells were 

obtained from the USGS National Water Information System 

(http://waterdata.usgs.gov/nwis).

Most of the winter groundwater level data were from 

shallow wells completed in major aquifers (groundwater 

levels less than 100 feet below land surface). Water-level data 

from several deep wells (groundwater levels greater than 100 

feet below land surface), such as those in the High Plains 

aquifer, also were analyzed. All groundwater level data were 

from groundwater sources that were likely to be hydraulically 

connected to local streams. Winter water-level measurements 

were used for the trend analysis because those measurements 

are least affected by seasonal transpiration and localized 

irrigation pumping. If data were unavailable for the period of 

late December through the end of March, groundwater levels 

collected during the year were omitted from analysis. Early 

January measurements were used when available, and when 

unavailable, the closest measurements made in late December, 

late January, February, or March were substituted. Trends in 

winter groundwater levels were calculated for the entire period 

of record for each well. 

Methods of Analysis

Computation of Base-Flow volume and BaseFlow Index

A base-flow separation method was used to determine 

the base-flow component of streamflow. Base-flow separation 

partitions the streamflow hydrograph into the components of 

direct runoff and base flow. Historically, hydrologists computed base-flow separation by hand, but different analysts 

given the same data would arrive at different base flows. A 

computerized method of base-flow separation was used for 

consistency and to handle large amounts of data. A FORTRAN 

program called Base Flow Index (BFI) was used for this report 

(Wahl, 1988; Wahl and Wahl, 1995). BFI implements a procedure developed by the Institute of Hydrology (1980a, 1980b) 

OK-4

OK-5

OK-6

OK-7

CENTRAL

SOUTHWEST

EAST

CENTRAL

WEST

CENTRAL

OKLAHOMA

A

N

S

A

S

OK-8 OK-9

SOUTHEAST

SOUTH

CENTRAL A

R

K

0 100 KILOMETERS

0 10050 MILES

KS-2 KS-3

KS-4

KS-7

KS-8 KS-9

OK-1

KS-1

OK-2 OK-3

KS-5 KS-6

CENTRAL

SOUTHWEST

SOUTHEAST

NORTHEAST

SOUTH CENTRAL

PANHANDLE

NORTHWEST

EAST CENTRAL

NORTH CENTRAL NORTHEAST

WEST CENTRAL

NORTH CENTRAL

KANSAS

TEXAS

COLORADO

MIS

S

O

U

RI

NEW

MEXICO

 

 

O K -9

SOUTHEAST

E X PL ANAT IO N

Climate Divisions not used in report

Climate Divisions in this report

State boundary

County boundary

Climate Division code and name

(National Oceanic and Atmospheric

Administration, 2009)

Figure 2. National Weather Service Climate Divisions used in annual and seasonal precipitation analysis.
10 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

that divides the water year into n-day increments, identifying 

the minimum streamflow during each n-day period. The BFI 

program defaults the n-day period to 5 days. Minimum streamflows then are compared to adjacent minimums to determine 

turning points on a base-flow hydrograph. Straight lines drawn 

between turning points define the base-flow hydrograph; the 

area beneath the hydrograph is an estimate of the volume 

of base flow. The ratio of the base-flow volume to the total 

volume of streamflow for the period is defined as the baseflow index. Although these procedures may not always yield 

the true base-flow volume of the stream, tests in Great Britain 

(Institute of Hydrology, 1980b), Canada (Swan and Condie, 

1983), and the United States (Wahl and Wahl, 1988) indicate 

that the results of this base-flow separation procedure were 

consistent and indicative of the true base-flow volume.

The default partition length of 5-day increments was not 

appropriate for certain stations. The defaults on the BFI program were modified for each station by varying the partition 

length (n-day, or N) periods. To determine an appropriate N for 

each station, the base-flow index values were all computed for 

N values ranging from 0 to 10 days. A graph for each station 

of base-flow index compared to N was constructed to visually 

identify a slope change. The number of days where the slope 

no longer substantially changed indicated an appropriate value 

for N (Wahl and Wahl, 1995). Substantial changes in slope 

were determined by using visual judgment. Figure 3 shows an 

example of the procedure used to select the optimal value for 

N. For the Blue River near Blue, Oklahoma, (station 34, table 

1), a substantial slope change occurs at N=2 days. 

The default value of the turning point parameter (f) 0.9 

was accepted at all stations. The BFI method has not proven to 

be highly sensitive to variations of f (Wahl and Wahl, 1995). In 

addition, careful considerations need to be made when using 

this program for regulated stations. For all stations in which 

streamflow was affected by regulation, the BFI output was 

examined to ensure that base-flow volume was appropriately 

computed. For stations in which streamflow was affected by 

regulation, computations of base-flow and total-flow volumes 

reflect a combination of unregulated streamflow and reservoir 

releases.

Graphical Analysis and LOESS Trend Lines

Prior to trend analysis, graphs were developed to visually 

identify potential trends in streamflow. Bar charts of base-flow 

volume, total-flow volume, base-flow index, annual peak flow, 

and annual precipitation were made for the analysis period 

for each station. Bar charts for the above parameters were 

developed only for the annual analysis periods. Bar charts 

also were developed for the number of extreme low-flow days 

(on an annual and seasonal basis) if at least 10 percent of the 

water years in one of the three analysis period types (annual, 

winter-spring, or summer-autumn) had at least 1 day where 

streamflow was zero or less than 1 ft3/s.

In addition to bar charts, LOESS trend lines also were 

made to aid in visual analysis of trends. LOESS or LOcally 

EStimated Scatterplot Smoothing (also referred to as LOWESS in other publications or LOcally WEighted Scatterplot 

Smoothing) (Cleveland and Devlin, 1988, Helsel and Hirsch, 

2002) is a nonparametric regression procedure that reduces 

the influence of outliers and displays a smooth or trend line 

for the entire range of data. A LOESS trend line is derived 

from a LOESS regression (Helsel and Hirsch, 2002). All bar 

charts and LOESS trend lines were produced in the statistical 

computer program S-Plus (Insightful Corporation, 2007). The 

LOESS lines were used for trend visualization purposes only 

and were not used to determine the statistical significance of 

trends.

LOESS plots were developed on an annual basis for 

base-flow volume, total-flow volume, base-flow index, peak 

streamflow, and precipitation and are shown on bar charts. For 

the number of extreme low-flow days, many stations did not 

have a substantial number of days where streamflow was zero 

or less than 1 ft3/s, which may result in a large number of zeros 

in the LOESS plots. An excessive number of zeros (greater 

than 70 percent, for example) in the data used for LOESS 

plots may result in trend lines that are highly variable because 

the lines are more susceptible to influence from periodic dry 

years, making visual analysis of trends difficult. For this 

report, LOESS trend lines were developed only when at least 

30 percent of the years during the analysis period (annual or 

seasonal) for each station had at least 1 day where streamflow 

was equal to zero or was less than 1 ft3/s. 

Kendall’s Tau Test

Kendall’s tau trend analysis was completed for annual 

and seasonal (winter-spring and summer-autumn) base-flow 

volume, total-flow volume and base-flow index. Kendall’s 

tau also was calculated for annual and seasonal precipitation, 

the number of days where streamflow was zero or less than 1 

ft3

/s, annual peak flow, and annual winter groundwater levels. 

The Kendall’s tau test was conducted by using the statistical 

computer program S-Plus contained in the U.S. Geological 

Survey library (Insightful Corporation, 2007; David Lorenz, 

U.S. Geological Survey, written commun., January 2009). 

Kendall’s tau (Kendall and Gibbons, 1990), which served 

as the statistical test for significant trends, is a nonparametric 

statistical test that can be used to indicate the likelihood of 

an upward or downward trend with time. The Kendall’s tau 

test is effective for identifying trends in streamflow because 

extremely high or low data outliers and skewness in the 

dataset have little effect on the outcome of the test (Helsel and 

Hirsch, 2002). Using the Kendall’s tau test, the rank of each 

data observation is compared to the rank of the data observations following it in a ranked annual series. If the data observations in the series are consistently higher than the first observation, the tau coefficient is positive. If the data observations 

in the series are consistently lower than the first observation, 
Methods of Analysis 11

the tau coefficient is negative. Tau coefficients range from -1.0 

to 1.0, where -1.0 indicates that every data observation has 

decreased with time, and 1.0 indicates that every data observation has increased with time. An equal number of negative and 

positive changes in data observations indicates that a trend 

does not exist, and the tau coefficient would be equal to zero.

For this report, a trend was considered to be statistically 

significant if the probability value (p-value, which is the probability that a true null hypothesis of no trend is erroneously 

rejected) was less than or equal to 0.05. This p-value represents a 95-percent confidence level in the correctness of the 

calculated trend. 

A trend slope is a measure of the magnitude of a trend 

and was computed by using the Sen Slope Estimator (Sen, 

1968; Helsel and Hirsch, 2002). The Sen slope is estimated 

by computing the median slope of all possible slopes between 

each possible two-point data pair in the time series, and like 

the Kendall’s tau estimate, is considered insensitive to extreme 

outliers (Dietz, 1989; Helsel and Hirsch, 2002, p. 267). 

Kendall’s tau analysis for the number of extreme lowflow days poses complications because streamflow for some 

stations for many years never are equal to zero or go below 

1 ft3

/s. These deficiencies in extreme low-flow days result in 

a potential for a high number of zeros in the dataset, which 

creates a lower limit on the dataset. However, the Kendall’s 

tau analysis is still possible because all years that have a 

lower limit (zero days) are computed as tied values (Helsel 

and Hirsch, 2002, p. 353). Similar to the LOESS trend line, 

Kendall’s tau was only calculated for datasets for which at 

least 30 percent of the years during the analysis period (annual 

or seasonal) had at least 1 day where streamflow was equal 

to zero or less than 1 ft3

/s. Although the sign of the estimated 

0

0.2

0.4

0.6

0.8

1

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10

ME D IAN ANNU AL BAS E -F L O W IND E X , IN AC R E -

F O O T P E R AC R E -F O O T

N-Day selected where 

slope change is minimized

Change in slope

PARTION LENGTH (N) IN DAYS

CHNAGE IN SLOPE, IN ACRE-FOOT PER

PARTITION LENGTH DAY

Figure 3. Procedure used to select an optimal partition length (N) for computation of baseflow volume by minimizing the slope change between a relation of median annual base-flow 

index and partition length for Blue River near Blue, Oklahoma, (USGS Station Identifier 

07332500; station 34, table 1).
12 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Sen slope is more accurate for data with a lower limit, the 

magnitude of the slope estimate is likely to be in error (Helsel 

and Hirsch, 2002, p. 353). For this reason, a Sen slope was not 

computed for the number of extreme low-flow days.

Streamflow data were first transformed into natural 

logarithms prior to the Kendall’s tau analysis to express the 

Sen slope roughly as a percent per year. The slope of a trend 

line fitted to the natural log of the data is equal to the average 

percentage growth in the original series because changes in the 

natural logarithm are roughly equivalent to percentage change 

in a data series (Helsel and Hirsch, 2002, p. 346). Transformations were not needed for base-flow index and the number of 

extreme low-flow days because base-flow index was already 

expressed as a percent, and the Sen slope for the number of 

days of extreme low flow was not computed.

Kendall’s Tau Test for Streamflow Volume 

Adjusted for Annual Precipitation

In the application of Kendall’s tau method used in this 

report, the only influence on streamflow being analyzed is 

time. However, variables other than time can have considerable influence on streamflow. Unfortunately, a strong correlation between annual precipitation and streamflow may obscure 

underlying trends in streamflow, such as downward trends that 

are caused by other factors such as surface-water diversions 

or groundwater withdrawals from the drainage basin. These 

“exogenous” variables can be precipitation, temperature, or 

other factors. By removing the annual and seasonal variation in streamflow caused by precipitation, the background 

underlying trends in streamflow can be more clearly observed 

(Helsel and Hirsch, 2002, p. 329). For this report, the procedure of removing the effects of annual precipitation from 

streamflow trends is referred to as “precipitation-adjusted” 

trend analysis. For the remainder of this report, base-flow and 

total-flow volumes are referred to collectively as “streamflow 

volume”. Precipitation-adjusted trends were calculated for 

annual and seasonal streamflow volumes to identify the presence of underlying trends in streamflow that are not associated 

with annual or seasonal variations in precipitation.

The influence of annual variability of precipitation on 

total-flow volume trends is intuitive. However, annual variability of precipitation also can influence annual base-flow 

volume. Precipitation from sequential storms can yield an 

elevated base-flow volume if the hydrograph from the first 

storm has not yet receded to prestorm levels prior to the start 

of another runoff event (fig. 4). Localized recharge from 

previous rainfall events also can lead to an elevated base-flow 

volume depending on the initial soil saturation at the start of 

a precipitation event (which affects the volume of overland 

and subsurface flow), the lag time between events occurring 

in the upper part of the watershed and the time when streamflow reaches the streamflow-gaging station, and the recharge 

rate and recharge potential of the aquifers that supply flow to 

a stream. These factors may result in a significant correlation 

between annual base-flow volume and annual precipitation, 

which can increase the likelihood that an upward trend in 

base-flow volume is because of an increase in precipitation 

(fig. 5). 

The error residuals from a regression between the streamflow parameter and annual precipitation can be computed, 

and a trend developed between the error residuals and time. 

This procedure results in a removal of the effect of annual or 

seasonal precipitation (Helsel and Hirsch, 2002, p. 331-335). 

Error residuals (R) were computed as:

R = Y –Ŷ (1) 

where,

 Y is observed annual or seasonal streamflow 

volume, and 

 Ŷ is the fitted value from a linear regression 

using annual precipitation to estimate 

annual streamflow volume.

Kendall’s tau was used to test for a time trend in error 

residuals (R) from the LOESS regression between annual and 

seasonal precipitation and annual and seasonal streamflow volume. This precipitation-adjusted streamflow trend, if significant, can be viewed as a trend that may be a result of factors 

other than the variation of annual or seasonal precipitation, 

such as withdrawals, diversions, and irrigation returns. 

For this report, a nonparametric approach (Helsel and 

Hirsch, 2002, p. 334) was selected because of the high likelihood of a skewed distribution of annual or seasonal streamflow and the possibility of a skewed or nonlinear relation 

between annual or seasonal precipitation and streamflow. 

LOESS was used to describe the relation between annual or 

100

1,000

10,000

100,000

3/30/2006

4/14/20064/29/20065/14/20065/29/2006

6/13/20066/28/2006

Base flow

Runoff Total flow

Separate Runoff Events

ST R E A MF L O W, IN C U BIC F E E T PE R 

SE C O ND

DA TE

Figure 4. Base-flow separation during sequential storms 

for Spring River near Quapaw, Oklahoma, (USGS Station 

Identifier 07188000; station 13, table 1).
Methods of Analysis 13

seasonal precipitation and annual and seasonal streamflow 

volume (Helsel and Hirsch, 2002, p. 336). 

When developing the LOESS regression, even though the 

technique allows for a curved relation, if the error residuals 

are not normally distributed or there are extreme outliers in 

the relation, the regression line may be biased towards those 

outliers that will affect the magnitude of the residuals and 

may result in a biased trend (Helsel and Hirsch, 2002, p. 332; 

David K. Mueller, U.S. Geological Survey, oral and written 

commun., March 2009). For this report, the LOESS regression 

was calculated on the natural logarithms of annual or seasonal 

precipitation and annual and seasonal streamflow volume. 

An example of the precipitation adjustment trend procedure is presented in figure 6 for Spavinaw Creek near Sycamore (station 15) (fig. 1). No trend in annual base-flow volume 

existed with a simple trend with time (fig. 6A). An increase 

in precipitation was observed during the analysis period (fig. 

6B). There is a statistically significant correlation between precipitation and base-flow volume (fig. 6C). A trend of the error 

residuals with time indicates further support for this observation because there is a statistically significant downward trend. 

The downward trend (fig. 6D) in residuals indicates that when 

precipitation is not considered in the trend, base-flow volume 

is decreasing. Another interpretation of this result is that with 

time, the same amount of precipitation in a given year is yielding a lesser volume of base flow than in previous years. 

The LOESS regression was developed for the natural 

logarithms of annual and seasonal base-flow volume, totalflow volume, and the natural logarithms of annual or seasonal 

precipitation. A partial t-test from a linear regression, which is 

a test to determine if the correlation between parameters is statistically significant (Ott and Longnecker, 1995, p. 590–597; 

Helsel and Hirsch, 2002, p. 311-312), was used to evaluate the 

correlation between the natural logarithms of annual and seasonal base-flow volume and total-flow volume, and the natural 

logarithms of annual, winter-spring, and summer-autumn precipitation. The relation with the highest correlation coefficient 

and t-value was selected as the precipitation parameter used in 

the LOESS regression. If there was no statistically significant 

correlation between streamflow volume (a t-value between 

-2.0 and 2.0) and any of the precipitation parameters, precipitation adjustment was not justified and was not calculated.

Canadian River at Bridgeport (station 18)

3.0 3.2 3.4 3.6 3.8 4.0 4.2

10

11

12

13

2.8 3.0 3.2 3.4 3.6 3.8

9

10

11

12

2.65 2.90 3.15 3.40 3.65 3.90 4.15

9

10

11

12

3.0 3.2 3.4 3.6 3.8 4.0

7

8

9

10

11

12

13

Best-fit line

Blue River near Blue (station 34) Illinois River near Tahlequah 

(station 16)

Little River near Sasakwa (station 19)

13

13.5

13.5

ANNUAL PRECIPITATION, IN NATURAL LOG OF INCHES

ANNUAL BASE-FLOW VOLUME, IN NATURAL LOG OF ACRE-FEET

Figure 5. Relation between annual base-flow volume and annual precipitation at four streamflow-gaging stations in Oklahoma. 

Station numbers are referenced on table 1.
14 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

B

Kendall tau: +0.09P-Value: 0.369

1960 1970 1980 1990 2000 2010

9.59.0

11.511.010.510.0

-0.5

-1.0

0.5

3.2 3.4 3.6 3.8 4.0 4.2

9.59.0

11.511.010. 510. 0

Error residual Error residual

LOESS Trend Line

Kendall tau: -0.22P-Value: 0.038

A

C

D

8 0

6 05 04 03 02 0

0.0

1960 1970 1980 1990 2000 2010

LOESS Trend Line

Kendall’ s tau trend line

Kendall’s tau trend line

1960 1970 1980 1990 2000 2010

ANNUAL WATER YEAR ANNUAL WATER YEAR

ANNUAL PRECIPITATION IN LOG OF INCHES ANNUAL WATER YEAR

ANNUAL BASE-FLOW VOLUME, IN

NATURAL LOG OF ACRE-FEET

ANNUAL BASE-FLOW VOLUME, IN

NATURAL LOG OF ACRE-FEET

ERROR RESIDUALS, IN NATURAL LOG OF

ACRE-FEET

ANNUAL PRECIPITATION, IN INCHES

howing (A) not significant 

base 

Trends in base-flow volume at Spavinaw Creek near Sycamore, Oklahoma, (USGS Station Identifier 07191220; station 15, table 1), s

s tau base-flow trend line over time, (B) annual precipitation over time, (C) LOESS relation between annual precipitation and 

s tau precipitation adjusted base-flow trend line over time in error residuals for the LOESS relation between annual base 

Figure 6.(p-value less than or equal to 0.5) Kendall’flow with error residuals, and (D) significant Kendall’flow and annual precipitation.
Trends in Base Flow, Total Flow, and Base-Flow Index 15

Several limitations of this approach exist for evaluation 

of trends in precipitation-adjusted streamflow volume. Even if 

streamflow volume and precipitation are significantly correlated, the result of precipitation-adjusted trend analysis may 

not be different than the result of simple trend analysis if the 

correlation is weak (the correlation has a low t-value or low 

R2, for example), because the residuals are substantially large 

in magnitude with a weak correlation. A weak correlation may 

indicate that streamflow is not dependent on the annual or 

seasonal precipitation but is more affected by other variables. 

For this report, results of precipitation adjustment are not presented for base-flow index. Precipitation adjustment could not 

be calculated for the annual or seasonal base-flow index for 29 

of 37 stations because base-flow index was not significantly 

correlated to precipitation. For the remainder of stations that 

did have a significant correlation between annual or seasonal 

base-flow index and precipitation, the average absolute t-test 

score was relatively low (less than 4.5). Such a low t-test score 

indicates that the correlation between variables is statistically 

significant (at the 95th percent confidence level) but weak. 

Precipitation and base-flow index were uncorrelated or weakly 

correlated probably because increases in precipitation result 

in an increase to base flow and total flow, which may affect 

the ratio between these two parameters. Most significant correlations were negative (increases in precipitation resulted in 

decreases in base-flow index).

In addition, trend analysis of precipitation-adjusted 

streamflow may be subject to serial auto-correlation. Serial 

auto-correlation is the correlation between a data point and the 

adjacent points in a time series (Helsel and Hirsch, 2002, p. 

251-252). Procedures used to compute trends in precipitationadjusted streamflow volume incorporate same-year data pairs 

of precipitation and streamflow in the LOESS relation. A 

drainage basin, which is fed by groundwater and not prone 

to flash floods, may result in base-flow volumes that also are 

correlated to precipitation amounts from previous years as a 

result of long-term aquifer recharge to an aquifer with substantial storage capacity after a series of years with above-average 

precipitation. In this example, trend analysis of precipitationadjusted streamflow, which incorporated a LOESS relation 

between same-year data pairs of precipitation and streamflow, 

would be biased toward upward trends for drainage basins that 

exhibit these characteristics because the correlation of base 

flow to precipitation from previous years was not accounted 

for. Whereas, this bias may be a limitation of the method, 

trends in precipitation-adjusted streamflow volume, which are 

subject to serial auto-correlation, may help to highlight those 

stations where streamflow volume may be affected by longterm recharge of underlying aquifers. This information can 

be beneficial for water-resources planning. Further analysis 

is warranted into the relation of streamflow to precipitation 

of previous years, or use of additional exogenous variables, 

to better evaluate how climate and recharge affect base-flow 

volume trends (David K. Mueller, U.S. Geological Survey, 

oral and written commun., May 2009).

The precipitation-adjusted methods used in this report 

only test for a change in the intercept in the relation between 

streamflow volume and precipitation. If there is a change in 

slope in this relation, the results of the trend analysis by using 

these procedures may or may not reflect those changes. Additional analysis into the changes in the relation between these 

two parameters would help to further investigate the causes of 

a change in slope (Helsel and Hirsch, 2002, p. 336). 

Trends in Base Flow, Total Flow, and 

Base-Flow Index

In this section, results of trend analysis for precipitation 

are presented for the 12 climate divisions, because precipitation change is the most direct potential cause of streamflow 

change. Next, results of trend analysis for base flow, total flow, 

and base-flow index are presented by station, for the study 

area, and then by major drainage basin. In subsequent sections, 

trends for peak flow, number of extreme low-flow days, and 

groundwater levels are described.

Precipitation Trend Analysis

Bar charts and LOESS plots of annual precipitation 

for all 12 climate divisions (fig. 2) analyzed in this report 

are presented in figures 7–9 (back of report). Results of the 

Kendall’s tau test for trends in annual and seasonal precipitation are presented in table 2 and figure 10. All 12 climate 

divisions had upward trends in annual and seasonal precipitation, but trends in many climate divisions were not statistically 

significant (fig. 2, table 2). These trends are similar to those 

reported by Tortorelli and others (2005) that summarized 

annual precipitation trends for climate divisions through 2003. 

All climate divisions that were analyzed in both this report and 

Tortorelli (2005) had upward trends in annual precipitation, 

some of which were not significant. More climate divisions 

indicated statistically significant upward trends in the analysis 

presented in this report than in Tortorelli (2005). This difference may have occurred because water years 2007 and 2008 

were considered wet years for many climate divisions in the 

state (National Climatic Data Center, National Oceanic and 

Atmospheric Administration, 2009).

In general, significant upward trends in precipitation 

were detected in central Oklahoma and central and southeastern Kansas (fig. 10). More climate divisions had statistically 

significant upward trends in total precipitation for annual 

water years (fig. 10) than in winter-spring or summer-autumn 

water years (fig. 10). Significant upward trends in annual 

precipitation were detected in western and central Oklahoma, 

and in south-central and southeast Kansas (fig. 10). Significant 

upward trends in winter-spring precipitation were detected for 

south-central and southeast Kansas and west-central Oklahoma (fig. 10). Significant upward trends in summer-autumn 
16 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 2. Results of Kendall’s tau trend analyses of total annual and seasonal precipitation in Oklahoma and portions of Kansas, water years 1895-20081.[shading indicates statistically significant upwards trend at 95-percent confidence level (probability value less than or equal to 0.05), no downwards trends were observed; yr, year]

Climate division 

number - region 

descriptor1

Climate 

division 

code

Total precipitation trends

Annual Winter-spring2 Summer-autumn2

Median 

precipitation 

(inches)

Kendall’s 

tau

Probability value

Trend slope Median 

precipitation 

(inches)

Kendall’s 

tau

Probability 

value

Trend slope Median 

precipitation 

(inches)

Kendall’s 

tau

Probability value

Trend slope

(inch/

year)

(percent) (inch/ year) (per- cent) (inch/ year) (per- cent)

Kansas

 7 - Southwest KS-7 18.770 0.091 0.152 0.017 0.093 7.560 0.033 0.611 0.004 0.048 11.060 0.052 0.419 0.008 0.069 8 - South Central KS-8 26.750 0.162 0.029 0.066 0.245 11.730 0.148 0.046 0.035 0.300 19.400 0.146 0.050 0.051 0.261 9 - Southeast KS-9 38.030 0.152 0.041 0.082 0.215 17.780 0.190 0.011 0.055 0.310 19.980 0.072 0.334 0.026 0.132

Oklahoma

 1 - Panhandle OK-1 19.620 0.096 0.133 0.021 0.108 8.100 0.065 0.313 0.010 0.118 11.270 0.076 0.234 0.013 0.112 2 - North Central OK-2 28.750 0.162 0.011 0.047 0.164 13.300 0.112 0.079 0.022 0.166 14.260 0.134 0.036 0.032 0.221 3 - Northeast OK-3 39.020 0.080 0.211 0.027 0.068 20.460 0.105 0.101 0.028 0.135 18.860 0.044 0.493 0.011 0.059 4 - West Central OK-4 26.520 0.172 0.007 0.047 0.176 12.470 0.129 0.043 0.027 0.213 13.170 0.115 0.072 0.025 0.187 5 - Central OK-5 33.640 0.142 0.026 0.050 0.149 17.320 0.112 0.079 0.024 0.136 16.370 0.118 0.063 0.027 0.168 6 - East Central OK-6 42.850 0.103 0.107 0.039 0.090 23.100 0.102 0.111 0.025 0.109 18.980 0.032 0.618 0.008 0.040 7 - Southwest OK-7 27.640 0.117 0.067 0.035 0.127 13.400 0.088 0.168 0.017 0.126 13.180 0.117 0.066 0.025 0.191 8 - South Central OK-8 37.040 0.086 0.177 0.032 0.087 20.350 0.050 0.439 0.012 0.058 16.310 0.092 0.150 0.021 0.131 9 - Southeast OK-9 48.430 0.115 0.072 0.048 0.099 28.670 0.052 0.413 0.016 0.057 18.540 0.108 0.089 0.028 0.152

Oklahoma Statewide

ST34 33.505 0.178 0.017 0.068 0.204 17.375 0.159 0.032 0.039 0.226 16.115 0.112 0.131 0.028 0.173

1From http://www.ncdc.noaa.gov/oa/climate/onlineprod/drought/ftppage.html2Winter-spring precipitation indicates that annual precipitation data used in the trend analysis were only from the months of November through May, and Summer-autumn indicates that annual precipitation data used in the trend analysis were only from the months of June through October. Water years (defined as the period from October 1 of the preceding calendar year through September 30 of the 

current calendar year) analyzed for the summer-autumn period also include October precipitation from the proceeding water year.
Trends in Base Flow, Total Flow, and Base-Flow Index 17

9

SOUTHEAST

E X PL ANAT IO N

0 100 KILOMETERS0 10050 MILES

CENTRAL

SOUTHWEST

NORTHEAST

SOUTH 

CENTRAL 

PANHANDLE

SOUTHWEST

SOUTHEAST SOUTH CENTRAL

NORTH CENTRAL

EAST

CENTRAL

WEST 

CENTRAL

KANSAS

TE XAS

ODAR OL OC

I R U OSSI M SASNAK RA SOUTHEAST KS-7 KS-8 OK-1 OK-2 OK-3 OK-4 OK-5 OK-6 OK-7 OK-8 OK-9 KS-9

O KLAHO MA

Annual Precipitation Winter-Spring Precipitation (November - May)

Summer-Autumn Precipitation (June - October)

CENTRAL

SOUTHWEST

NORTHEAST

SOUTH 

CENTRAL 

PANHANDLE

SOUTHWEST

SOUTHEAST SOUTH CENTRAL

NORTH CENTRAL

EAST

CENTRAL

WEST 

CENTRAL

KANSAS

TE XAS

ODAR OL OC

I R U OSSI M SASNAK RA SOUTHEAST 

O KLAHO MA

KS-7 KS-8

OK-1 OK-2 OK-3

OK-4

OK-5 OK-6

OK-7 OK-8 OK-9

KS-9

CENTRAL

SOUTHWEST

NORTHEAST

SOUTH 

CENTRAL 

PANHANDLE

SOUTHWEST

NORTH CENTRAL

EAST

CENTRAL

WEST 

CENTRAL

KANSAS

TE XAS

ODAR OL OC

I R U OSSI M SASNAK RA SOUTHEAST 

O KLAHO MA

SOUTH 

CENTRAL SOUTH- EAST

KS-7 KS-8

OK-1 OK-2 OK-3

OK-4

OK-5 OK-6

OK-7 OK-8 OK-9

KS-9

Significant upward

Upward trend in precipitation, not significant

State boundary

C limate D ivision Boundary

trend in precipitation

Climate Division number and name

eather Service Climate Divisions (National Oceanic and au trend analysis of annual precipitation data from National W Results of Kendall’s T Figure 10.

Atmospheric Administration, 2009).
18 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

precipitation were only detected for north-central Oklahoma 

and south-central Kansas (fig. 10). 

Streamflow Volume and Base-Flow Index Trend 

Analysis

Graphs showing LOESS plots for annual base-flow 

volume, total-flow volume, and base-flow index are shown 

in figures 11–47 (back of report). LOESS plots for Beaver 

River at Beaver, Oklahoma, (station 21) and North Canadian 

River near Seiling, Oklahoma, (station 22) were created for 

the entire period of record, and not just the period used for 

statistical analysis (table 1), for visual comparison of streamflow during the unregulated period and irrigated period. 

Results of trend analysis of unadjusted and precipitationadjusted base-flow volume, total-flow volume, and base-flow 

index for annual and seasonal water years are presented in 

tables 3–9. Maps were developed to display spatial patterns 

in trend results for annual and seasonal streamflow volume 

and base-flow index (figs. 48–62, back of report). Maps show 

the direction of the trend and whether the trend was statistically significant. Maps showing results from trends in unadjusted and precipitation-adjusted base-flow and total-flow 

volumes are presented for visual comparison (figs. 48–62). 

The significance and direction of a trend in precipitation–

adjusted streamflow volume in which streamflow volume 

was not significantly correlated to precipitation would be the 

same as a trend in unadjusted streamflow volume. For ease of 

comparison between maps, if trends in precipitation-adjusted 

streamflow volume were not calculated, the results from trend 

analysis of unadjusted streamflow volume also were displayed 

on the map with trends in precipitation-adjusted streamflow 

volume.

Significant trends in base-flow volume were detected 

at most stations, most of which were upward in direction. 

Significant trends in annual or seasonal base-flow volume 

were detected at 22 of 37 stations analyzed. All stations with 

significant trends (upward or downward) in winter-spring 

or summer-autumn base-flow volume (21 and 17 stations, 

respectively) also had significant trends in annual base-flow 

volume in the same direction (tables 3 through 5). Significant upward trends in annual or seasonal base-flow volume 

were detected for 19 stations (19 stations the annual period, 

18 stations for the winter-spring period, and 14 stations for 

the summer-autumn period). Significant downward trends in 

annual and seasonal base-flow volume were detected for 3 

stations: Cimarron River near Kenton and Forgan, Oklahoma, 

and Beaver River at Beaver, Oklahoma, (stations 6, 7, and 21, 

respectively).

Precipitation-adjustment changed the results (significance only or significance and direction) of annual or seasonal 

base-flow trends for 12 stations (9 stations for the annual 

period, 6 stations for the winter-spring period, and 5 stations 

for the summer-autumn period). Precipitation adjustment 

did not change the results (significance only or significance 

and direction) of most significant trends in unadjusted baseflow volume (tables 3–5). However, precipitation adjustment 

reduced the magnitude of most of the significant upward 

base-flow trends. Significant trends in precipitation-adjusted 

base-flow volume that were in the same direction as significant 

trends in unadjusted base-flow volume for each respective 

season were detected for 13 stations for the annual period, 

14 stations for the winter-spring period, and 10 stations for 

the summer-autumn period. For the annual period, significant 

downward trends in precipitation-adjusted base-flow volume 

that were not significant prior to precipitation adjustment were 

detected for two stations: Arkansas River near Arkansas City, 

Kansas, and Spavinaw Creek near Sycamore, Oklahoma, (stations 1 and 15, respectively). Only station 1 had a significant 

downward trend in winter-spring base-flow volume that was 

not significant prior to precipitation adjustment (table 4).

Fewer stations had significant trends in total-flow volume 

than stations that had significant trends in base-flow volume, 

and most of the significant trends in annual and winter-spring 

total-flow volume were upward (tables 6–8). Many stations 

that had significant upward trends in total-flow volume had 

significant upward trends in base-flow volume for the same 

period with the exception of station 14, which had a significant 

upward trend in winter-spring total-flow volume but no significant trend in base-flow volume. Significant trends in annual or 

seasonal total-flow volume were detected for 14 stations, 9 of 

which had significant upward trends (8 stations for the annual 

period, 9 stations for the winter-spring period, and 4 stations 

for the summer-autumn period). Significant downward trends 

in total-flow volume were detected for four stations for the 

annual period, three stations for the winter-spring period, and 

five stations for the summer-autumn period.

Precipitation adjustment changed the trend results 

(significance only or significance and direction) of annual or 

seasonal total-flow volume for 13 stations (8 stations for the 

annual period, 7 stations for the winter-spring period, and 5 

stations for the summer-autumn period). No significant trends 

in precipitation-adjusted total-flow volume were detected 

where significant trends were detected for unadjusted totalflow volume for five stations for the annual period, and four 

stations for the winter-spring period and summer-autumn 

period (table 7). Significant upward trends in precipitationadjusted total-flow volume that were in the same direction as 

significant upward trends for unadjusted total-flow volume for 

each respective station were detected for three stations for the 

annual period, five stations for the winter-spring period, and 

no stations for the summer-autumn period. Significant downward trends in precipitation-adjusted annual total-flow volume 

that were not significant prior to precipitation adjustment were 

detected for three stations: North Canadian River near Seiling, 

Oklahoma, Salt Fork Red River at Mangum, Oklahoma, and 

North Fork Red River near Carter, Oklahoma, (stations 22, 26, 

and 27, respectively) (table 6). Significant downward trends 

in precipitation-adjusted winter-spring total-flow volume that 

were not significant prior to precipitation adjustment were 

detected for three stations: Cimarron River near Waynoka, 
Trends in Base Flow, Total Flow, and Base-Flow Index 19

Table 3. Results of trend analysis for annual base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; 

the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange 

shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS 

station ID

Median 

base-flow 

volume 

(acre-feet)

Annual base-flow trends Annual adjusted base-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation 

parameter1

T-test 

score

Trend 

slope 

(percent/

year)2

Tau2 p-value2

1 07146500 725,800 -0.15 -0.03 0.690 A 6.73 -0.45 -0.18 0.031

2 07151000 208,700 1.72 0.27 0.001 A 9.29 0.88 0.19 0.027

3 07152000 96,760 1.85 0.38 <0.001 A 7.48 1.00 0.30 0.000

4 07152500 2,035,000 1.58 0.17 0.168 A 6.31 0.34 0.03 0.808

5 07153000 22,210 3.78 0.28 0.010 WS 7.44 2.25 0.33 0.002

6 07154500 768 -3.95 -0.36 <0.001 WS 1.02 -- -- --

7 07156900 25,130 -1.75 -0.74 <0.001 A 0.34 -- -- --

8 07158000 40,480 1.11 0.18 0.025 A 6.18 0.47 0.11 0.190

9 07159100 201,700 1.22 0.14 0.256 A 3.41 0.46 0.07 0.570

10 07161450 327,100 2.25 0.38 <0.001 A 7.29 1.70 0.39 0.000

11 07171000 501,100 1.45 0.13 0.242 WS 8.65 -0.37 -0.05 0.665

12 07172000 44,740 1.95 0.17 0.108 WS 8.17 -0.25 -0.02 0.832

13 07188000 588,200 0.83 0.19 0.020 A 8.77 0.44 0.12 0.157

14 07191000 29,380 0.92 0.14 0.104 A 7.87 0.09 0.02 0.867

15 07191220 42,100 0.48 0.09 0.369 A 5.74 -0.61 -0.22 0.038

16 07196500 288,300 0.60 0.19 0.020 A 9.47 0.26 0.12 0.136

17 07197000 88,230 1.00 0.21 0.016 A 10.31 0.30 0.11 0.214

18 07228500 95,340 3.72 0.42 <0.001 WS 2.66 3.48 0.44 0.000

19 07231000 52,890 3.04 0.20 0.057 A 7.94 0.07 0.01 0.967

20 07231500 336,000 3.60 0.33 0.002 A 6.39 2.04 0.28 0.007

21 07234000 53,840 -3.17 -0.38 <0.001 WS 2.01 -3.88 -0.44 <0.001

22 07238000 49,120 1.06 0.14 0.107 A 6.17 0.48 0.07 0.409

23 07242000 224,700 1.48 0.25 0.002 A 8.17 0.92 0.26 0.002

24 07243500 123,200 1.13 0.11 0.318 WS 7.69 0.86 0.14 0.204

25 07247500 15,050 0.26 0.02 0.884 A 6.83 -0.41 -0.07 0.537

26 07300500 9,509 2.31 0.35 <0.001 A 5.01 1.56 0.29 0.000

27 07301500 28,330 2.33 0.35 <0.001 A 5.52 1.48 0.24 0.004

28 07311500 4,476 1.87 0.10 0.371 A 5.79 0.18 0.02 0.885

29 07315700 6,332 4.00 0.26 0.010 A 8.13 1.76 0.18 0.071

30 07316000 454,800 1.12 0.21 0.016 A 6.52 0.42 0.13 0.143
20 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 3. Results of trend analysis for annual base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; 

the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange 

shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS 

station ID

Median 

base-flow 

volume 

(acre-feet)

Annual base-flow trends Annual adjusted base-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation 

parameter1

T-test 

score

Trend 

slope 

(percent/

year)2

Tau2 p-value2

31 07316500 5,635 3.96 0.43 <0.001 A 3.82 3.29 0.36 0.000

32 07326500 116,100 3.34 0.37 <0.001 A 4.40 2.69 0.33 0.002

33 07331000 377,900 3.51 0.37 <0.001 A 5.23 2.20 0.35 0.001

34 07332500 65,340 0.40 0.09 0.254 A 11.01 0.04 0.02 0.850

35 07335700 14,200 1.01 0.24 0.025 A 5.57 0.76 0.19 0.076

36 07336200 221,000 -1.53 -0.17 0.234 A 7.22 -0.46 -0.05 0.726

37 07337900 65,680 0.76 0.10 0.322 A 7.19 -0.03 -0.02 0.883

1

 Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summerautumn indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October.

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.

Table 4. Results of trend analysis for winter-spring base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed] 

Station 

no.

(fig. 1)

USGS station ID

Median 

winterspring 

base-flow 

volume 

(acre-feet)

Winter-spring base-flow trends Winter-spring adjusted base-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation 

parameter1

T-test 

score

Trend slope 

(percent/

year)2

Tau2 p-value2

1 07146500 413,200 -0.14 -0.03 0.690 WS 4.89 -0.52 -0.17 0.049

2 07151000 118,700 1.82 0.27 0.001 WS 6.79 1.03 0.18 0.035

3 07152000 66,070 1.91 0.37 <0.001 A 5.05 1.36 0.35 <0.001

4 07152500 1,171,000 1.28 0.13 0.323 WS 4.89 1.12 0.15 0.237

5 07153000 15,040 3.57 0.22 0.044 WS 7.66 2.29 0.25 0.021

6 07154500 419 -3.18 -0.28 0.002 WS 1.73 -- -- --

7 07156900 16,660 -1.66 -0.72 <0.001 WS 0.73 -- -- --

8 07158000 29,940 1.23 0.21 0.011 A 5.07 0.67 0.14 0.092

9 07159100 119,400 1.00 0.08 0.495 WS 3.16 1.14 0.15 0.201

10 07161450 178,300 2.41 0.40 <0.001 A 5.68 2.01 0.39 <0.001
Trends in Base Flow, Total Flow, and Base-Flow Index 21

Table 4. Results of trend analysis for winter-spring base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed] 

Station 

no.

(fig. 1)

USGS station ID

Median 

winterspring 

base-flow 

volume 

(acre-feet)

Winter-spring base-flow trends

Trend 

slope Tau p-value (percent/

year)

Precipitation 

parameter1

Winter-spring adjusted base-flow trends

Trend slope T-test (percent/ Tau2

score year)2

p-value2

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

07171000

07172000

07188000

07191000

07191220

07196500

07197000

07228500

07231000

07231500

07234000

07238000

07242000

07243500

07247500

07300500

07301500

07311500

07315700

07316000

07316500

07326500

07331000

07332500

07335700

07336200

07337900

288,900

34,400

381,100

21,210

31,990

207,600

67,300

67,930

32,060

235,000

38,650

35,410

119,000

92,350

12,890

7,572

20,510

3,179

3,585

248,400

5,016

77,240

256,700

43,410

12,870

207,100

56,230

0.89

1.44

1.04

0.95

0.42

0.66

0.98

3.57

2.70

3.42

-2.90

1.14

1.74

0.92

0.26

2.49

2.51

2.09

4.47

1.21

3.80

3.08

3.07

0.56

0.97

-2.00

0.65

0.06

0.12

0.21

0.12

0.07

0.19

0.23

0.40

0.18

0.30

-0.30

0.17

0.27

0.07

0.03

0.38

0.37

0.11

0.22

0.20

0.40

0.41

0.34

0.10

0.20

-0.23

0.10

0.573

0.270

0.010

0.165

0.486

0.017

0.011

<0.001

0.090

0.004

<0.001

0.062

0.001

0.508

0.762

<0.001

<0.001

0.333

0.027

0.018

<0.001

<0.001

0.001

0.200

0.054

0.118

0.340

WS

WS

WS

WS

A

A

A

WS

WS

A

WS

A

A

WS

WS

A

A

A

A

WS

WS

A

WS

A

A

A

A

7.55

6.32

7.94

6.50

5.04

8.57

9.28

2.62

6.06

5.74

2.11

5.23

6.66

7.81

6.21

3.40

4.70

4.75

6.12

6.44

3.17

3.02

4.91

8.84

5.71

5.63

6.84

-0.58

-0.73

0.45

-0.61

-0.74

0.31

0.35

3.54

1.44

2.04

-3.74

0.68

1.17

0.52

-0.72

1.83

1.71

0.18

1.64

0.90

3.68

2.50

1.97

0.20

0.72

-0.77

0.02

-0.06

-0.07

0.11

-0.09

-0.20

0.11

0.11

0.41

0.14

0.28

-0.42

0.15

0.27

0.07

-0.16

0.26

0.25

0.02

0.15

0.20

0.35

0.33

0.31

0.06

0.20

-0.08

0.00

0.588

0.485

0.190

0.287

0.051

0.187

0.223

<0.001

0.180

0.007

<0.001

0.099

0.001

0.522

0.147

0.001

0.002

0.885

0.138

0.019

0.001

0.002

0.003

0.457

0.063

0.591

0.971

1

Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summerautumn indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October. 

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.
22 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 5. Results of trend analysis for summer-autumn base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station ID; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; Adjusted 

trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; SA, summer-autumn total precipitation; the shaded values 

are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median 

summer-autumn baseflow volume 

(acre-feet)

Summer-autumn base-flow trends

Trend 

slope Tau p-value (percent/

year)

Summer-autumn adjusted base-flow trends

Precipi- Trend slope tation T-test (percent/ Tau2 p-value2

param- score year)2

eter1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

07146500

07151000

07152000

07152500

07153000

07154500

07156900

07158000

07159100

07161450

07171000

07172000

07188000

07191000

07191220

07196500

07197000

07228500

07231000

07231500

07234000

07238000

07242000

07243500

07247500

07300500

07301500

07311500

07315700

07316000

280,400

54,170

29,380

769,100

5,153

107

8,734

6,662

52,860

105,000

99,580

6,712

164,100

3,520

10,170

73,320

17,950

12,010

10,020

68,500

6,733

13,190

75,190

30,560

1,550

1,367

4,680

1,461

1,161

172,400

0.18

1.98

1.94

3.01

4.71

-6.34

-2.04

0.83

0.77

1.94

2.12

2.41

0.28

0.97

0.94

0.63

0.92

4.89

2.99

3.90

-5.33

1.65

1.20

0.44

-1.19

2.11

2.13

0.39

2.37

0.63

0.03

0.23

0.30

0.17

0.26

-0.37

-0.67

0.07

0.05

0.28

0.13

0.18

0.06

0.08

0.11

0.17

0.18

0.36

0.14

0.26

-0.34

0.13

0.18

0.02

-0.10

0.18

0.20

0.04

0.16

0.11

0.690

0.007

<0.001

0.189

0.018

<0.001

<0.001

0.361

0.712

0.001

0.242

0.087

0.484

0.360

0.279

0.034

0.043

0.001

0.180

0.013

<0.001

0.131

0.024

0.831

0.375

0.027

0.017

0.753

0.116

0.196

A

A

A

A

A

SA

SA

A

A

A

A

A

A

A

A

A

A

A

A

A

A 

A

A

A

A

A

A

A

A

A

13.48

13.53

12.57

5.87

6.29

1.98

0.85

7.88

5.25

9.13

5.47

7.63

8.38

8.99

6.99

10.57

9.24

4.44

8.91

6.12

3.17

7.19

9.11

6.25

3.97

6.55

8.97

6.74

6.93

6.92

-0.37

0.51

0.91

0.59

2.51

--

--

-0.81

-0.36

1.28

1.47

1.21

0.18

-0.30

-0.28

0.25

0.40

3.64

-0.11

2.09

-5.82

-0.05

0.79

0.35

-1.19

1.47

0.38

0.20

1.05

0.16

-0.14

0.12

0.25

0.06

0.23

--

--

-0.11

-0.06

0.30

0.12

0.15

0.05

-0.05

-0.05

0.11

0.12

0.38

-0.01

0.21

-0.41

-0.01

0.19

0.03

-0.11

0.13

0.04

0.02

0.09

0.04

0.109

0.147

0.002

0.662

0.038

--

--

0.190

0.629

<0.001

0.251

0.143

0.538

0.546

0.647

0.169

0.178

0.001

0.917

0.051

<0.001

0.952

0.022

0.796

0.318

<0.001

0.645

0.847

0.369

0.664
Trends in Base Flow, Total Flow, and Base-Flow Index 23

Oklahoma, Salt Fork Red River at Mangum, Oklahoma, and 

Kiamichi River near Big Cedar, Oklahoma, (stations 8, 26, and 

35) (table 7). A significant downward trend in precipitationadjusted summer-autumn total-flow volume that was not 

significant prior to precipitation adjustment was only detected 

for one station, North Canadian River near Seiling, Oklahoma, 

(station 22) (table 8). 

Significant trends in base-flow index were detected for a 

majority of stations, and most of these trends were upward in 

direction (table 9). Significant trends in base-flow index for 

the annual or seasonal period were detected for 25 stations. 

Significant upward trends in base-flow index were detected for 

22 stations for the annual period, 18 stations for the winterspring period, and 16 stations for the summer-autumn period. 

A significant downward trend in winter-spring base-flow index 

was detected for only one station, Arkansas River near Arkansas City, Kansas, (station 1). A significant downward trend in 

summer-autumn base-flow index was detected for only one 

station, Cimarron River near Kenton, Oklahoma, (station 6). 

Many stations that had significant upward trends in 

annual or seasonal base-flow index also had significant upward 

trends in annual or seasonal base-flow volume. Significant 

upward trends in both base-flow index and base-flow volume, 

accompanied by no significant downward trends in total-flow 

volume, were detected for 18 stations annually or seasonally 

(17 for the annual period, 12 stations for the winter-spring 

period, and 10 stations for the summer-autumn period). These 

results indicate that significant upward trends in annual or 

seasonal base-flow index at these stations likely were driven 

by increases in base flow as opposed to decreases in runoff. 

Significant upward trends in base-flow index followed by 

significant downward trends in annual and seasonal base-flow 

volume and total-flow volume were detected for 2 stations: 

Cimarron River near Forgan, Oklahoma, and Beaver River 

at Beaver, Oklahoma, (stations 7 and 21, respectively). 

Even though streamflow volume was decreasing, base-flow 

decreased at a slower rate than runoff decreased at these stations, which is the likely cause of significant upward trends 

in base-flow index. Only one station, Cimarron River near 

Waynoka, Oklahoma, (station 8) had an upward trend in 

summer-autumn base-flow index, a downward trend in totalflow volume, and no significant trend in base-flow volume 

for the same period. Upward trends in base-flow index at this 

station likely are driven by decreases in runoff as opposed to 

increases in base-flow volume. Only one station, Cimarron 

River near Kenton, Oklahoma, (station 6), had a downward 

trend in summer-autumn base-flow index, base-flow volume, 

and total-flow volume. Downward trends in summer-autumn 

base-flow index at this station are likely driven by faster 

decreases in runoff than in base-flow volume.

Table 5. Results of trend analysis for summer-autumn base-flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station ID; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; Adjusted 

trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; SA, summer-autumn total precipitation; the shaded values 

are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median 

summer-autumn baseflow volume 

(acre-feet)

Summer-autumn base-flow trends Summer-autumn adjusted base-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation

parameter1

T-test 

score

Trend slope 

(percent/

year)2

Tau2 p-value2

31 07316500 755 7.71 0.42 <0.001 A 6.09 4.62 0.34 0.001

32 07326500 45,280 3.42 0.29 0.005 A 7.16 2.20 0.28 0.007

33 07331000 121,600 3.91 0.33 0.001 A 6.36 2.40 0.31 0.003

34 07332500 20,180 -0.16 -0.04 0.670 A 12.99 -0.43 -0.14 0.079

35 07335700 1,116 1.65 0.12 0.250 SA 4.49 1.86 0.20 0.071

36 07336200 15,280 -6.27 -0.26 0.072 SA 4.63 -1.16 -0.07 0.624

37 07337900 6,022 1.49 0.16 0.107 SA 5.57 1.86 0.20 0.059

1

Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summerautumn indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October.

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.
24 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 6. Results of trend analysis for annual total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median 

total-flow 

volume 

(acre-feet)

Annual total-flow trends Annual adjusted total-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation

parameter1

T-test 

score

Trend slope 

(percent/year)2 Tau2 p-value2

1 07146500 1,452,000 0.08 0.01 0.894 A 6.73 -0.30 -0.16 0.0614

2 07151000 588,600 1.32 0.20 0.019 A 9.29 0.31 0.08 0.3354

3 07152000 359,800 1.45 0.24 0.003 A 7.48 0.34 0.13 .119

4 07152500 4,055,000 2.13 0.24 0.058 A 6.31 0.64 0.09 0.4856

5 07153000 142,600 2.68 0.18 0.103 A 7.44 0.66 0.10 0.3749

6 07154500 6,235 -3.42 -0.37 <0.001 SA 1.35 -- -- --

7 07156900 29,660 -2.61 -0.74 <0.001 SA -0.62 -- -- --

8 07158000 167,000 -1.14 -0.20 0.016 A 6.18 -1.61 -0.39 <0.001

9 07159100 562,900 0.24 0.02 0.865 A 3.41 -0.41 -0.05 0.6701

10 07161450 976,700 1.31 0.23 0.005 A 7.29 0.78 0.22 0.0079

11 07171000 1,862,000 0.90 0.11 0.298 A 8.65 -0.08 -0.01 0.9482

12 07172000 201,100 1.68 0.18 0.091 WS 8.17 -0.01 0.00 0.9919

13 07188000 1,454,000 0.59 0.12 0.132 A 8.77 0.12 0.04 0.6374

14 07191000 235,300 0.52 0.09 0.299 A 7.87 -0.35 -0.11 0.2297

15 07191220 70,850 0.83 0.12 0.233 A 5.74 -0.54 -0.16 0.119

16 07196500 665,500 0.32 0.09 0.271 A 9.47 -0.05 -0.02 0.786

17 07197000 236,300 0.65 0.14 0.115 A 10.31 0.05 0.02 0.8234

18 07228500 198,100 1.62 0.18 0.100 A 3.72 0.80 0.14 0.2084

19 07231000 230,700 1.60 0.14 0.202 A 7.94 -0.95 -0.18 0.0823

20 07231500 998,500 2.11 0.23 0.031 A 6.39 0.56 0.12 0.2531

21 07234000 228,000 -5.71 -0.60 <0.001 WS 1.58 -- -- --

22 07238000 107,800 -0.23 -0.04 0.688 A 6.17 -1.12 -0.23 0.009

23 07242000 505,500 1.01 0.17 0.038 A 8.17 0.44 0.14 0.0756

24 07243500 560,900 0.64 0.07 0.552 A 7.69 -0.32 -0.06 0.5976

25 07247500 105,800 0.06 0.01 0.955 A 6.83 -0.26 -0.09 0.4383

26 07300500 51,020 -0.63 -0.12 0.156 A 5.01 -1.12 -0.24 0.0027

27 07301500 79,660 -0.07 -0.01 0.881 A 5.52 -0.75 -0.18 0.0256

28 07311500 80,800 0.63 0.05 0.681 A 5.79 -0.90 -0.13 0.2358

29 07315700 89,690 1.85 0.15 0.147 A 8.13 -0.36 -0.05 0.6124

30 07316000 1,835,000 0.39 0.06 0.455 A 6.52 -0.16 -0.04 0.6061
Trends in Base Flow, Total Flow, and Base-Flow Index 25

Spatial Patterns in Results for Entire Study Area

Maps were used to evaluate spatial patterns in stations 

with significant trends. Trend results were highly variable 

throughout the State. However, some recurring patterns in 

locations of stations with similar trend results were detected 

(figs. 48–62). 

Base Flow

Significant downward trends in annual and seasonal 

base-flow volume were detected for stations 6, 7, and 21 in the 

Oklahoma Panhandle. In contrast, upward trends in annual and 

seasonal base-flow volume were detected for many stations 

in central, southwestern, and south-central Oklahoma. For 

many stations in southwestern and south-central Oklahoma, 

precipitation adjustment did not change the results (direction 

or significance) of the trends in unadjusted base-flow volume. 

A recurring spatial pattern in the locations of stations with 

precipitation-adjusted base-flow trends (fig. 63) was observed 

for a grouping of 12 stations in central and north-central Oklahoma (stations 2, 3, 5, 10, 20, 23), and a grouping of stations 

in southwestern and south-central Oklahoma (stations 18, 26, 

27, 31, 32, and 33) (fig. 63). Significant upward annual and 

winter-spring base-flow trends even after precipitation adjustment were detected for stations in these groupings. For the 

summer-autumn period, upward trends in unadjusted summerautumn base-flow volume also were detected for the grouping of stations in southwestern and south-central Oklahoma 

(fig. 52), but there was no clear spatial pattern in the locations 

of stations with significant precipitation-adjusted base-flow 

trends (fig. 53). Prior to precipitation adjustment, significant 

upward trends in annual or seasonal base-flow volume were 

detected for four stations in eastern Oklahoma—defined as stations located in Neosho-Verdigris, Lower Arkansas, and RedSulphur Basins (figs. 48, 50, and 52). However, after precipitation adjustment, significant upward trends in base-flow volume 

were not detected for any stations in eastern Oklahoma and a 

significant downward trend in precipitation-adjusted annual 

base-flow volume was detected for one station, Spavinaw 

Creek near Sycamore, Oklahoma, (station 15) (figs. 49, 51, 

and 53). 

Total Flow

Similar to base flow, significant downward trends in 

total-flow volume were detected for stations in the Oklahoma 

Panhandle. No definitive regional patterns were detected for 

unadjusted or adjusted total-flow volume trends for stations 

in west-central Oklahoma (stations 8, 22, 26–28, and 31). 

For the annual and winter-spring period, a spatial pattern in 

the locations of stations with significant upward unadjusted 

Table 6. Results of trend analysis for annual total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; P-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median 

total-flow 

volume 

(acre-feet)

Annual total-flow trends

Trend 

slope Tau p-value (percent/

year)

Precipitation

parameter1

Annual adjusted total-flow trends

T-test Trend slope Tau2

score (percent/year)2 p-value2

31

32

33

34

35

36

37

07316500

07326500

07331000

07332500

07335700

07336200

07337900

11,560

271,500

1,054,000

184,100

64,540

1,214,000

348,200

2.63

2.84

2.86

0.17

0.37

-1.86

0.92

0.29

0.31

0.32

0.03

0.08

-0.13

0.16

0.004

0.003

0.002

0.728

0.464

0.388

0.111

A

A

A

A

A

A

A

4.83

4.40

5.23

11.01

5.57

7.22

7.19

1.17

1.78

1.47

-0.17

-0.12

-0.34

0.04

0.19

0.30

0.27

-0.05

-0.06

-0.07

0.01

0.0614

0.0042

0.007

0.506

0.6008

0.6238

0.9269

1

 Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summerautumn indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October.

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.
26 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 7. Results of trend analysis for winter-spring total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median winterspring totalflow volume 

(acre-feet)

Winter-spring total-flow trends Winter-spring adjusted total-flow trends

Trend 

slope 

(percent/

year)

Tau p-value

Precipitation

parameter1

T-test 

score

Trend slope 

(percent/

year)2

Tau2 p-value2

1 07146500 786,200 0.22 0.04 0.650 WS 4.89 -0.41 -0.13 0.119

2 07151000 324,800 1.41 0.17 0.039 WS 6.79 0.42 0.08 0.341

3 07152000 227,000 1.64 0.25 0.002 WS 10.55 0.54 0.15 0.071

4 07152500 2,578,000 1.40 0.17 0.178 WS 4.89 1.05 0.15 0.237

5 07153000 88,920 1.88 0.13 0.221 WS 7.66 0.52 0.06 0.567

6 07154500 930 -3.41 -0.26 0.005 WS 2.12 -3.52 -0.27 0.003

7 07156900 19,800 -2.17 -0.75 <0.001 SA -1.17 -- -- --

8 07158000 83,060 -0.64 -0.11 0.168 WS 5.07 -1.01 -0.26 0.002

9 07159100 309,600 -0.48 -0.05 0.670 WS 3.16 -0.11 -0.02 0.865

10 07161450 543,400 1.79 0.26 0.002 WS 9.50 1.29 0.27 0.001

11 07171000 1,277,000 0.33 0.04 0.729 WS 7.55 -0.56 -0.07 0.544

12 07172000 166,600 1.51 0.15 0.166 WS 6.32 -0.58 -0.08 0.473

13 07188000 877,200 0.90 0.15 0.062 WS 7.94 0.01 0.00 0.988

14 07191000 151,000 1.52 0.19 0.028 WS 6.50 -0.52 -0.11 0.216

15 07191220 56,450 0.63 0.10 0.340 WS 5.04 -0.97 -0.16 0.111

16 07196500 489,300 0.26 0.06 0.426 WS 8.57 -0.05 -0.01 0.868

17 07197000 172,400 0.67 0.16 0.077 A 9.28 0.01 0.00 0.975

18 07228500 125,500 1.20 0.15 0.183 WS 4.25 0.91 0.17 0.134

19 07231000 165,400 1.32 0.13 0.241 WS 6.06 -0.26 -0.03 0.786

20 07231500 590,100 2.27 0.21 0.044 WS 5.74 0.86 0.14 0.199

21 07234000 87,280 -4.65 -0.48 <0.001 WS 2.67 -4.67 -0.52 <0.001

22 07238000 56,380 0.33 0.05 0.562 WS 5.23 -0.27 -0.06 0.496

23 07242000 274,900 1.19 0.19 0.019 WS 6.66 0.89 0.25 0.003

24 07243500 388,200 0.86 0.07 0.552 WS 7.81 0.11 0.01 0.920

25 07247500 87,110 0.07 0.01 0.937 WS 6.21 -0.43 -0.14 0.213

26 07300500 26,240 -0.05 -0.01 0.945 WS 6.10 -0.67 -0.17 0.041

27 07301500 44,350 0.26 0.06 0.478 WS 4.70 -0.05 -0.01 0.889

28 07311500 43,350 1.10 0.06 0.595 WS 4.75 0.16 0.02 0.885

29 07315700 56,240 2.08 0.15 0.138 WS 6.12 -0.26 -0.05 0.650

30 07316000 788,800 0.47 0.07 0.414 WS 6.44 0.15 0.02 0.794
Trends in Base Flow, Total Flow, and Base-Flow Index 27

total-flow volume trends was observed for most stations in the 

grouping of stations in central and north-central Oklahoma 

(fig. 63) and stations along the Washita River, but there was no 

clear spatial pattern in the locations of stations with significant 

trends in precipitation-adjusted total-flow volume. For most 

stations with significant upward trends in total-flow volume, 

precipitation adjustment changed these trends to not significant upward or downward trends, except for three stations 

in central and south-central Oklahoma, Cimarron River near 

Ripley, Oklahoma, Washita River at Anadarko, Oklahoma, and 

Washita River near Dickson, Oklahoma, (stations 10, 32, and 

33, respectively). Precipitation adjustment did not change the 

significance or direction of upward trends in annual or winterspring total-flow volume for these stations. In eastern Oklahoma, with the exception of Kiamichi River near Big Cedar, 

Oklahoma, (station 35), where a downward trend in precipitation-adjusted winter-spring total-flow volume was detected, 

and Big Cabin Creek near Big Cabin, Oklahoma, (station 14), 

where an upward trend in unadjusted winter-spring base-flow 

volume was detected, no stations had significant total-flow 

volume trends before or after precipitation adjustment. 

Base-Flow index

Similar to base flow, significant upward trends in annual 

and seasonal base-flow index were detected for many stations 

in central and western Oklahoma. A significant downward 

trend in winter-spring base-flow index was detected for one 

station near north-central Oklahoma, Arkansas River near 

Arkansas City, Kansas, (station 1). The westernmost station 

in the study area, Cimarron River near Kenton, Oklahoma, 

(station 6), was the only station in western Oklahoma with a 

significant downward trend in base-flow index, and the trend 

was detected only for the summer-autumn period (table 9). 

Significant upward trends in annual or seasonal base-flow 

index were detected only for three stations in eastern Oklahoma (stations 13, 16, and 35) (figs. 60–62).

Results by Major Drainage Basin

Red Headwaters

Stations in the Red Headwaters Basin include Salt Fork 

Red River at Mangum, Oklahoma, (station 26) and North Fork 

Red River near Carter, Oklahoma, (station 27) (figs. 36, 37, 

and 48). Whereas, trends at these stations were highly variable between the annual and seasonal periods and between 

unadjusted and precipitation-adjusted streamflow volume, 

most significant trends in base-flow volume and base-flow 

index were upward in direction, and most significant trends 

in total-flow volume were downward in direction. In general, 

Table 7. Results of trend analysis for winter-spring total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; ac-ft, acre-feet; 

Adjusted trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; WS, winter-spring total precipitation; the 

shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards trend, orange shade 

indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

(fig. 1)

USGS

station

ID

Median winterspring totalflow volume 

(acre-feet)

Winter-spring total-flow trends

Trend 

slope Tau p-value (percent/

year)

Winter-spring adjusted total-flow trends

Precipi- Trend slope tation T-test (percent/ Tau2 p-value2

param- score year)2

eter1

31

32

33

34

35

36

37

07316500

07326500

07331000

07332500

07335700

07336200

07337900

7,333

142,600

591,000

134,800

53,450

1,076,000

295,800

2.38

3.04

2.83

0.29

0.32

-1.23

0.68

0.29

0.32

0.32

0.05

0.04

-0.13

0.13

0.004

0.002

0.002

0.538

0.691

0.362

0.193

WS

WS

WS

WS

WS

A

WS

4.41

4.58

4.91

8.84

5.71

5.63

6.84

2.02

1.89

1.53

0.11

-0.43

-0.35

-0.20

0.28

0.28

0.27

0.03

-0.25

-0.07

-0.09

0.006

0.007

0.008

0.721

0.019

0.624

0.379

1

Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summerAutumn indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October.

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.
28 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 8. Results of trend analysis for summer-autumn total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; ac-ft, acre-feet; Adjusted 

trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; SA, summer-autumn total precipitation; WS, winter-spring 

total precipitation; the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards 

trend, orange shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no.

 (fig. 1)

USGS station ID

Median summerautumn totalflow volume 

(acre-feet)

Summer-autumn total-flow trends Summer-autumn adjusted total-flow trends

Trend slope 

(percent/

year)

Tau p-value

Precipitation

parameter1

T-test 

score

Trend slope 

(percent/

year)2

Tau2 p-value2

1 07146500 632,500 0.19 0.04 0.682 A 13.48 -0.49 -0.15 0.071

2 07151000 207,300 1.25 0.14 0.107 A 13.53 -0.24 -0.05 0.530

3 07152000 162,900 1.31 0.20 0.013 A 12.57 0.48 0.10 0.212

4 07152500 1,814,000 2.90 0.21 0.089 A 5.87 1.25 0.16 0.200

5 07153000 41,680 2.24 0.11 0.296 A 6.29 1.08 0.10 0.387

6 07154500 4,548 -3.71 -0.36 <0.001 SA 1.86 -- -- --

7 07156900 9,880 -2.92 -0.67 <0.001 WS -0.56 -- -- --

8 07158000 68,740 -1.91 -0.23 0.005 SA 7.88 -2.33 -0.34 <0.001

9 07159100 223,600 1.16 0.09 0.443 A 5.25 0.06 0.01 0.977

10 07161450 418,800 0.85 0.13 0.129 A 9.13 0.44 0.11 0.188

11 07171000 558,600 0.65 0.05 0.681 A 5.47 0.30 0.04 0.745

12 07172000 41,030 2.06 0.15 0.160 SA 7.63 0.94 0.10 0.368

13 07188000 395,000 -0.21 -0.03 0.698 A 8.38 -0.39 -0.08 0.318

14 07191000 42,010 -0.40 -0.03 0.714 SA 8.99 -0.88 -0.13 0.137

15 07191220 13,780 0.52 0.06 0.533 A 6.99 -0.83 -0.12 0.219

16 07196500 137,700 0.49 0.10 0.236 A 10.57 0.00 0.00 0.996

17 07197000 40,970 0.87 0.11 0.209 A 9.24 0.07 0.01 0.883

18 07228500 49,960 1.95 0.13 0.246 SA 4.44 1.69 0.17 0.128

19 07231000 53,220 1.28 0.07 0.503 A 8.91 -0.57 -0.07 0.530

20 07231500 308,000 1.77 0.14 0.179 A 6.12 0.74 0.11 0.298

21 07234000 124,300 -8.13 -0.58 <0.001 SA 1.09 -- -- --

22 07238000 38,800 -1.11 -0.11 0.214 A 7.19 -2.10 -0.31 <0.001

23 07242000 187,000 0.58 0.08 0.307 A 9.11 0.33 0.08 0.356

24 07243500 200,700 0.35 0.03 0.814 A 6.25 0.06 0.01 0.937

25 07247500 14,700 -0.25 -0.03 0.762 SA 3.97 0.72 0.07 0.522

26 07300500 19,550 -1.40 -0.19 0.020 SA 5.02 -1.76 -0.26 0.001

27 07301500 23,850 -0.58 -0.06 0.434 SA 8.97 -1.02 -0.15 0.068

28 07311500 36,990 -1.20 -0.07 0.545 SA 6.74 -1.08 -0.10 0.358

29 07315700 23,270 0.86 0.06 0.552 SA 6.93 0.66 0.08 0.450

30 07316000 691,900 0.23 0.03 0.750 A 6.92 -0.19 -0.03 0.698
Trends in Base Flow, Total Flow, and Base-Flow Index 29

there was a shift from runoff-dominated streamflow to base 

flow-dominated streamflow at those two stations.

Significant upward trends in annual and seasonal baseflow volume were detected at both stations (figs. 48, 50, 

and 52). After precipitation adjustment, the upward trends 

remained significant (figs. 49, 51, and 53), except for station 

27 for the summer-autumn period.

Some significant downward trends in total-flow volume 

were detected for stations in this basin both before and after 

precipitation adjustment (figs. 54–59). Prior to precipitation 

adjustment, no significant trends in annual or winter-spring 

total-flow volume were detected at either station (figs. 54 and 

56). A significant downward trend in summer-autumn totalflow volume was observed, however, for station 26 (fig. 58). 

After precipitation adjustment, however, significant downward trends in annual total-flow volume at both stations were 

detected (fig. 55); whereas, the downward trend in winterspring total-flow volume at station 26 became significant (fig. 

57). Precipitation adjustment did not change the direction or 

significance of summer-autumn total-flow volume trends at 

either station (fig. 59).

Significant upward trends in base-flow index were 

detected at both stations both annually and seasonally (figs. 

60–62). Upward trends in base-flow index for both stations 

appear to be a result of either upward trends in base-flow 

volume, downward trends in total-flow volume, or both. This 

observation indicates that base flow has likely increased; 

whereas, runoff has likely decreased at these stations. 

Red-Washita

Stations in the Red-Washita Basin include Washita River 

stations—the Washita River near Cheyenne, at Anadarko, and 

near Dickson, Oklahoma, (stations 31, 32, and 33, respectively); Red River stations that include tributaries to the Red 

River — Deep Red Creek near Randlett, Oklahoma, (station 28), and Mud Creek near Courtney, Oklahoma, (station 

29); and one main-stem Red River station— Red River near 

Gainesville, Texas, (station 30) (figs. 31–33, 48). Trends generally differed between the Washita River and the Red River 

stations. All trends that were significant in this basin were also 

upward in direction.

Significant upward trends in base-flow volume were 

detected both annually and seasonally for all Washita River 

stations, even after precipitation adjustment, but not for all 

Red River stations (figs. 48–53). Significant upward trends 

in annual and winter-spring base-flow volume were detected 

for stations 29 and 30 prior to precipitation adjustment. Most 

of the base-flow trends (either annual or seasonal) were not 

significant after precipitation-adjustment, with the exception of Red River near Gainesville, Texas (station 30) for the 

winter-spring period that had an upward base-flow trend that 

remained significant (fig. 51). Station 28 did not have any 

annual or seasonal base-flow trends before or after precipitation adjustment.

Significant upward trends in total-flow volume were 

detected for all three Washita River stations, annually and 

Table 8. Results of trend analysis for summer-autumn total flow volume for 37 selected streamflow-gaging stations in and near 

Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; ac-ft, acre-feet; Adjusted 

trend, trend adjusted for changes in annual or seasonal precipitation; A, annual total precipitation; SA, summer-autumn total precipitation; WS, winter-spring 

total precipitation; the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant upwards 

trend, orange shade indicates a statistically significant downwards trend; --, trend test not performed]

Station 

no. 

 (fig. 1)

USGS station ID

Median summerautumn totalflow volume 

(acre-feet)

Summer-autumn total-flow trends

Trend slope 

(percent/ Tau p-value

year)

Summer-autumn adjusted total-flow trends

Precipi- Trend slope tation T-test (percent/ Tau2 p-value2 param- score year)2 eter1

31

32

33

34

35

36

37

07316500

07326500

07331000

07332500

07335700

07336200

07337900

3,034

111,800

431,600

46,910

9,918

176,300

50,010

3.78

2.74

2.35

-0.27

0.58

-4.93

1.22

0.25

0.25

0.21

-0.04

0.05

-0.27

0.13

0.011

0.016

0.037

0.599

0.660

0.065

0.206

A

A

A

A

SA

SA

SA

6.09

7.16

6.36

12.99

4.49

4.63

5.57

1.45

1.30

1.29

-0.46

0.55

-0.70

1.16

0.13

0.20

0.20

-0.10

0.08

-0.10

0.16

0.198

0.054

0.052

0.226

0.464

0.498

0.107

1

Winter-spring indicates that year precipitation totals used in trend adjustment were only from the months of November through May and summer-autumn 

indicates that yearly precipitation totals used in trend adjustment were only from the months of June through October.

2

If the t-test score for correlation with the precipitation parameter was between -2.0 and 2.0, then trend adjustment was not performed.
30 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 Table 9. Results of trend analysis for annual, winter-spring, and summer-autumn base-flow index for 37 selected streamflow-gaging stations in and near Oklahoma. —Continued [no., number; USGS station ID, U.S. Geological Survey station identifier; fraction, ratio of base-flow volume to total-flow volume; Tau, Kendall’s tau; p-Value, probability level; <, less than; ac-ft, acre-feet; the shaded values are statistically significant at the 95 percent confidence interval, green shade indicates a statistically significant upwards trend, orange shade indicates a statistically significant downwards trend] Station no. (fig. 1) USGS station ID Annual base p-value-flow index trends Winter-spring base-flow index trends1 Summer-autumn base-flow index trends1 Median base- flow index (frac- tion) Trend Slope (fraction/ year) Tau p-value Media base- flow index (frac- tion) Trend Slope (fraction/ year) Tau p-value Median base- flow index (frac- tion) Trend Slope (fraction/ year) Tau p-value

1 07146500 0.48 -0.001 -0.15 0.078 0.59 -0.002 -0.18 0.036 0.46 -0.000 -0.04 0.6582 07151000 0.33 0.002 0.23 0.006 0.44 0.000 0.09 0.279 0.34 0.002 0.17 0.0383 07152000 0.26 0.001 0.19 0.018 0.34 0.001 0.06 0.487 0.19 0.001 0.18 0.0224 07152500 0.49 -0.002 -0.17 0.168 0.49 -0.000 -0.01 0.935 0.49 -0.004 -0.17 0.1685 07153000 0.16 0.002 0.29 0.008 0.17 0.002 0.22 0.042 0.13 0.002 0.26 0.0166 07154500 0.09 -0.000 -0.07 0.437 0.45 -0.001 -0.07 0.461 0.03 -0.001 -0.25 0.0057 07156900 0.82 0.007 0.59 <0.001 0.84 0.005 0.51 <0.001 0.79 0.007 0.52 <0.0018 07158000 0.27 0.006 0.60 <0.001 0.43 0.007 0.45 <0.001 0.11 0.003 0.43 <0.0019 07159100 0.35 0.003 0.22 0.069 0.39 0.007 0.31 0.010 0.33 -0.002 -0.08 0.495

10 07161450 0.34 0.003 0.42 <0.001 0.41 0.002 0.17 0.036 0.32 0.002 0.28 0.001

11 07171000 0.25 0.002 0.17 0.119 0.26 0.001 0.09 0.386 0.19 0.003 0.19 0.079

12 07172000 0.20 0.000 0.02 0.848 0.24 0.000 0.03 0.769 0.16 0.000 0.02 0.86413 07188000 0.40 0.001 0.25 0.003 0.43 0.001 0.10 0.220 0.37 0.002 0.17 0.03414 07191000 0.11 0.000 0.11 0.202 0.13 -0.000 -0.03 0.780 0.08 0.001 0.16 0.07615 07191220 0.56 -0.000 -0.00 1.000 0.55 -0.001 -0.05 0.608 0.59 0.001 0.06 0.53316 07196500 0.46 0.001 0.22 0.006 0.44 0.002 0.22 0.005 0.55 0.001 0.06 0.42617 07197000 0.38 0.001 0.16 0.077 0.38 0.001 0.15 0.084 0.48 0.001 0.03 0.76418 07228500 0.35 0.009 0.40 <0.001 0.51 0.009 0.38 0.001 0.26 0.005 0.26 0.01919 07231000 0.26 0.004 0.28 0.008 0.26 0.004 0.30 0.005 0.25 0.001 0.09 0.39120 07231500 0.31 0.005 0.44 <0.001 0.32 0.005 0.36 0.001 0.25 0.004 0.25 0.020
Trends in Base Flow, Total Flow, and Base-Flow Index

31

Table 9. Results of trend analysis for annual, winter-spring, and summer-autumn base-flow index for 37 selected streamflow-gaging stations in and near Oklahoma. —Continued[no., number; USGS station ID, U.S. Geological Survey station identifier; fraction, ratio of base-flow volume to total-flow volume; Tau, Kendall’s tau; p-Value, probability level; <, less than; ac-ft, acre-feet; the shaded values are statistically significant at the 95 percent confidence interval, green shade indicates a statistically significant upwards trend, orange shade indicates a statistically significant downwards trend]

Annual base p-value-flow index trends Winter-spring base-flow index trends1 Summer-autumn base-flow index trends1

Median Media Median 

Station USGS base- Trend base- Trend base- Trend 

no. station flow Slope flow Slope flow Slope Tau p-value Tau p-value Tau p-value (fig. 1) ID index (fraction/ index (fraction/ index (fraction/

(frac- year) (frac- year) (frac- year)

tion) tion) tion)

21 07234000 0.19 0.007 0.43 <0.001 0.44 0.007 0.32 <0.001 0.10 0.004 0.35 <0.00122 07238000 0.53 0.008 0.52 <0.001 0.61 0.007 0.45 <0.001 0.35 0.008 0.43 <0.00123 07242000 0.40 0.002 0.32 <0.001 0.44 0.002 0.20 0.014 0.41 0.002 0.17 0.03224 07243500 0.26 0.001 0.13 0.221 0.26 0.000 0.05 0.678 0.21 -0.000 -0.02 0.88425 07247500 0.15 0.000 0.01 0.937 0.16 0.000 0.03 0.796 0.11 -0.000 -0.06 0.59826 07300500 0.19 0.006 0.52 <0.001 0.32 0.007 0.47 <0.001 0.08 0.003 0.46 <0.00127 07301500 0.36 0.008 0.58 <0.001 0.46 0.009 0.53 <0.001 0.18 0.004 0.42 <0.00128 07311500 0.05 0.001 0.14 0.217 0.08 -0.000 -0.02 0.866 0.03 0.000 0.13 0.25629 07315700 0.08 0.001 0.31 0.002 0.09 0.002 0.27 0.007 0.06 0.001 0.15 0.12430 07316000 0.27 0.002 0.35 <0.001 0.33 0.002 0.25 0.003 0.27 0.002 0.16 0.06531 07316500 0.54 0.007 0.37 <0.001 0.65 0.006 0.38 <0.001 0.23 0.007 0.38 <0.00132 07326500 0.48 0.004 0.26 0.013 0.58 0.002 0.11 0.278 0.42 0.004 0.20 0.05933 07331000 0.38 0.003 0.31 0.003 0.42 0.002 0.12 0.219 0.33 0.004 0.24 0.01634 07332500 0.36 0.001 0.11 0.175 0.35 0.001 0.14 0.078 0.44 0.000 0.01 0.88035 07335700 0.24 0.002 0.21 0.047 0.26 0.002 0.22 0.038 0.16 0.001 0.12 0.27636 07336200 0.18 -0.000 -0.01 0.944 0.20 -0.001 -0.07 0.657 0.11 0.002 0.09 0.55937 07337900 0.17 0.000 0.01 0.927 0.19 0.000 0.06 0.545 0.12 0.000 0.04 0.728

1Winter-spring indicates that annual BFI fractions used in trend adjustment were only from the months of November through May and summer-autumn indicates that annual BFI 

fractions used in trend analysis were only from the months of June through October.
32 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

34

20

19

37

35

33

32

31

30

29

28

27

26 25

24

23

22

21

18

17

1

12

KANSAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarron

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

Red-W ashita

!

#

#

!

#

!

!

!

!

#

!

!

!

!

!

!!

#

!

#

!

!

#

!

!

#

#

!

!

!

#

#

#

!

!

!

!

State border

Streams

Area containing streamflow -

gaging stations with significantupwards trends in annual orseasonal precipitation-adjustedbase flow

#

Numbers correspond to tabl e 1

Albers Equal-Area Conic Projection.

North American Datum 1983.

31

!

22 Other streamflow gaging stations

used in trend

TEXAS

EXPLANATION

analysis

KILOMETERS

Areas where streamflow-gaging stations had significant upward trends in annual or seasonal precipitation-adjusted base-flow volume. Figure 63.
Trends in Base Flow, Total Flow, and Base-Flow Index 33

seasonally, but no significant annual or seasonal trends in 

total-flow value were detected for the Red River stations 

(even after precipitation adjustment) (figs. 54–59). Upward 

trends at all three Washita River stations were still upward in 

direction after precipitation adjustment, but the significance of 

many annual or seasonal trends changed. Station 31, the most 

upstream station in the basin, did not have significant trends 

in precipitation-adjusted annual or summer-autumn totalflow volume (figs. 55 and 59); whereas, trends in total-flow 

volume after precipitation adjustment remained significant and 

upward for the two downstream stations. This observation was 

the same for the winter-spring period except that the upward 

trend in total-flow volume at the upstream station 31 remained 

significant after precipitation adjustment (fig. 57). For the 

summer-autumn period, precipitation adjustment resulted in 

no trends at all three Washita River stations (fig. 59). 

Significant upward trends in annual base-flow index were 

found at all three stations along the Washita River and two of 

three Red River stations (fig. 60). At these stations, upward 

trends in winter-spring and summer-autumn base-flow index 

also were detected, but not all trends were significant (figs. 

61 and 62). Station 31, the upstream station, had significant 

upward trends for both seasons, station 32 did not have significant trends, and station 33 had significant upward trends 

during the summer-autumn period only. Significant upward 

trends in annual and winter-spring base-flow index were 

detected at stations 29 and 30, but significant trends for the 

summer-autumn base-index were not observed. No significant 

base-flow index trends were detected at station 28.

Upper Cimarron

Stations in this basin include Cimarron River near Kenton 

and Forgan, Oklahoma, (stations 6 and 7, respectively) (figs. 

16, 17, and 48). Significant downward trends in streamflow 

volume were detected for these two stations both annually 

and seasonally (figs. 48–59). Trends in precipitation-adjusted 

streamflow volume were not calculated for either station annually or seasonally because these parameters were not significantly correlated to precipitation. 

Base-flow index trends were not significant for the annual 

and winter-spring periods for station 6 (figs. 60 and 61), but 

a significant downward trend was observed for the summerautumn period (fig. 62). However, a significant upward trend 

in annual and seasonal base-flow index was observed for station 7. A possible reason for the difference in results between 

the two stations may be that base flow was a much lesser component of total flow at station 6 than station 7, and therefore, 

decreasing total flow at station 6 played a greater role in the 

observed base-flow index trends than at station 7 (figs. 16 and 

17). Base flow generally is higher at station 7 than at station 6, 

and is decreasing at a slower rate than total flow, which would 

result in upward trends in base-flow index. 

Lower Cimarron

Stations in the Lower Cimarron Basin include Cimarron 

River near Waynoka, Dover, and Ripley, Oklahoma, (stations 

8, 9, and 10, respectively) (figs. 18–20, 48). In general, trend 

results for stations in the Lower Cimarron Basin were different from the Upper Cimarron Basin. Although trend results 

were highly variable for stations in this basin, upward trends 

in streamflow volume annually and seasonally were detected 

even after precipitation adjustment (figs. 48-–59). In general, 

significant downward trends in streamflow volume in the 

Upper Cimarron River transition to significant upward trends 

in a downstream direction. 

Station 8, which is the most upstream station in the basin, 

showed a significant upward trend in annual and winterspring base-flow volume but did not show a significant trend 

in summer-autumn base-flow volume or annual and seasonal 

precipitation-adjusted base-flow volume (figs. 48–52). No significant trends in base-flow volume were detected for station 9. 

Station 10, which is the most downstream station in the basin, 

showed significant upward trends in annual and seasonal baseflow volume even after precipitation adjustment. 

Results of trends remained generally unchanged for 

annual total-flow volume for all three stations after precipitation adjustment. An exception to this pattern was found for 

the winter-spring period, for which precipitation adjustment 

resulted in a significant downward trend in total-flow volume 

for station 8 (fig. 57). A notable observation is that streamflow at station 9, which is between stations 8 and 10, did not 

have any significant trends in streamflow volume, even after 

precipitation adjustment. 

Significant upward trends in annual and seasonal baseflow index were detected for stations 8 and 10 (figs. 60–62). 

All three stations had significant upward trends in winterspring base-flow index (fig. 61).

North Canadian

Stations in the North Canadian Basin include Beaver 

River at Beaver, which also is the North Canadian River 

(station 21), North Canadian near Seiling and Wetumka, 

Oklahoma, (stations 22 and 23), and Deep Fork near Beggs, 

Oklahoma, (station 24). In general, moving downstream along 

the North Canadian River, downward trends in streamflow 

volume transitioned to upward trends (figs. 31–34, 48). 

In the upper part of the North Canadian Basin, station 

21 had significant downward trends in annual and seasonal 

base-flow volume (figs. 48, 50, and 52). Precipitation adjustment was not calculated for this station because streamflow 

volume and precipitation were not significantly correlated for 

any season. No significant trends in base-flow volume were 

detected for the next station downstream (station 22) even 

after precipitation adjustment. However, moving downstream 

to station 23, a significant upward trend in base-flow volume 

was detected during the annual and seasonal periods; this trend 

result did not change after precipitation adjustment. Deep Fork 

near Beggs (station 24), a tributary to the North Canadian 
34 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

River, did not have any significant unadjusted or adjusted 

base-flow trends.

Similar to base-flow volume, a significant downward 

trend in total-flow volume was observed at station 21 annually 

and seasonally. No significant trends in unadjusted total-flow 

volume were detected for station 22, however, after precipitation adjustment, significant downward trends were detected 

for the annual and summer-autumn period only. No significant 

trends in winter-spring total-flow volume were detected for 

this station even after precipitation adjustment. Significant 

upward trends in total-flow volume were detected for station 

23 during the annual and winter-spring periods only (figs. 54 

and 56), but after precipitation adjustment, the annual totalflow volume trend was not significant; whereas, the winterspring upward trend remained significant (figs. 55 and 57). 

Similar to base-flow volume, no significant trends in total-flow 

volume were detected for station 24.

All three main-stem North Canadian River stations had 

significant upward trends in base-flow index (figs. 60–62). 

Similar to base flow and total flow, no significant base-flow 

index trends were detected for station 24. Station 21 had 

similar results to station 7 in the Upper Cimarron. At both stations, significant downward trends in streamflow volume were 

detected for all periods (annual and seasonal), and upward 

trends in base-flow index also were detected. This observation 

indicated that total flow was decreasing at a faster rate than 

base flow. Station 22 did not have significant trends in baseflow volume, but had significant downward trends in annual 

and summer-autumn total-flow volume. This observation indicated that, similar to station 21, the upward trends in base-flow 

index were likely caused by decreases in runoff rather than 

increases in base flow.

Lower Canadian

Stations in the Lower Canadian Basin include the Canadian River at Brideport, Oklahoma, and at Calvin, Oklahoma 

(stations 18 and 20, respectively), and Little River near 

Sasakwa, Oklahoma, (station 19) which enters the Canadian River upstream from station 20 (figs. 28–30, 48). Trend 

results for these stations were variable between the annual and 

seasonal periods and for unadjusted and precipitation-adjusted 

streamflow volume, but all trends that were significant were 

upward in direction.

Most of the base-flow trends for stations along the mainstem of the Canadian River were upward and significant (figs. 

48–53). A significant upward trend in base-flow volume was 

observed for station 18 both annually and seasonally, even 

after precipitation adjustment. Moving downstream to station 

20, the results were the same as station 18, except that the 

summer-autumn base-flow trends became insignificant after 

precipitation adjustment. However, no significant trends in 

base-flow volume were detected for station 19 before or after 

precipitation adjustment. 

Upward trends in total-flow volume (annually or seasonally) were detected for some stations on the Canadian River 

prior to precipitation adjustment (figs. 54–59). No significant 

trends in total-flow volume were detected for station 18, but 

significant upward trends in annual and winter-spring totalflow volume were detected downstream. No significant trends 

in precipitation-adjusted total-flow volume were detected for 

any station in the basin. No significant trends in total-flow 

volume were detected for station 19 before or after precipitation adjustment.

All three stations had significant upward trends in baseflow index for the annual and winter-spring periods (figs. 

60–62). The mainstem Canadian stations also had upward 

trends in the summer-autumn base-flow index, but the upward 

trend at station 19 was not significant. Because significant 

upward trends in total-flow volume were detected prior to and 

after precipitation adjustment, upward trends in base-flow 

index are likely caused by increases in base-flow volume as 

opposed to decreases in runoff.

Arkansas-Keystone

Stations in the Arkansas-Keystone Basin include the 

tributaries to the Arkansas River: Salt Fork Arkansas River at 

Tonkawa, Oklahoma, Chikaskia River near Blackwell, Oklahoma, and Black Bear Creek at Pawnee, Oklahoma, (station 

2, 3, and 5, respectively), and one main-stem Arkansas River 

station, Arkansas River at Ralston, Oklahoma, (station 4) 

(figs. 12–15, 48). Another main-stem Arkansas River station, 

Arkansas River near Arkansas City, Kansas, (station 1) is not 

in the Arkansas-Keystone Basin, but is upstream from and in 

close proximity to the basin boundary and was included in the 

discussion of this basin.

Trends in the Arkansas-Keystone Basin were highly 

variable, but similarities were detected in streamflow volume 

trends for tributaries to the Arkansas River, whereas few similarities in trends were detected at the two main-stem Arkansas 

River stations. Most trends in streamflow volume that were 

significant were also upward in direction.

Significant upward trends in base-flow volume were 

detected for all three tributaries to the Arkansas River for the 

annual and winter-spring periods (figs. 48–53). After precipitation adjustment, however, results for these stations generally 

remained the same except for the summer-autumn period 

where the upward precipitation-adjusted base-flow trend at 

station 2 was not significant. No significant upward trends in 

annual or seasonal base-flow volume were detected for either 

of the main-stem Arkansas River stations. After precipitation 

adjustment, the annual and winter-spring base-flow trends 

at station 1, the upstream station, were downward and significant, whereas the trend in annual and seasonal base-flow 

volume at station 4 downstream did not change in significance. 

Precipitation adjustment did not change the results of baseflow trends on the main-stem Arkansas River stations for the 

summer-autumn period.

Some significant upward total-flow trends were detected 

for the tributaries to the Arkansas River (stations 2 and 3 for 

the annual and winter-spring period and only station 3 for 
Trends in Base Flow, Total Flow, and Base-Flow Index 35

the summer-autumn period) (figs. 54–59). After precipitation 

adjustment, however, no significant trends in annual or seasonal total-flow volume were detected at any of these stations. 

No significant trends in total-flow volume were detected at 

either Arkansas River main-stem station even after precipitation adjustment. 

Significant upward trends in base-flow index were 

detected for the tributary stations during the annual and 

summer-autumn periods (figs. 60–62). Only station 5 had a 

significant upward trend in winter-spring base-flow index. 

Most significant base-flow trends found at these three stations 

were upward in direction; whereas, total-flow trends generally were not significant. This observation indicates that the 

increases in base-flow index were likely caused by increases in 

base-flow volume rather than decreases in runoff. Results were 

different along the main-stem Arkansas River stations and 

the Arkansas River tributary stations. No significant trends in 

base-flow index were detected for either station for the annual 

and summer-autumn period, but a significant downward trend 

was observed at the upstream station (station 1) for the winterspring period. Because downward trends in winter-spring 

base-flow volume were detected for station 1 (which were significant only for precipitation-adjusted base-flow volume) but 

no significant trends in total-flow volume were detected, the 

significant downward trend in base-flow index is likely caused 

by decreases in base flow rather than decreases in runoff at 

this station.

Neosho-Verdigris

The Neosho-Verdigris Basin includes three stations that 

are tributaries to the Neosho River: Spring River near Quapaw, Oklahoma, (station 13), Big Cabin Creek near Big Cabin, 

Oklahoma, (station 14), and Spavinaw Creek near Sycamore, 

Oklahoma, (station 15) (figs. 23–25, 48). This basin also 

includes Verdigris River stations, including Verdigris River 

near Lenapah (station 11) and Caney River near Elgin, Kansas, 

(station 12) (fig. 48). Most stations in this basin did not have 

significant streamflow volume or base-flow index trends. 

Only station 13, the easternmost station in the basin, had 

a significant upward trend in base-flow volume but only for 

the annual and winter-spring periods (figs. 48–53). After precipitation adjustment, however, trends at station 13 were not 

significant, and a significant downward trend in precipitationadjusted base-flow volume was observed at station 15 for the 

annual period.

No significant trends in total-flow volume were detected 

for most stations in this basin (figs. 54–59) except for station 

14, which had an upward trend in total-flow volume only for 

the winter-spring period (fig. 56). No significant trends in 

total-flow volume were detected after precipitation adjustment.

No base-flow index trends were significant for stations 

in this basin except for station 13, where significant upward 

trends were detected during the annual and summer-autumn 

periods (figs. 60–62). Based on the observation of upward 

base-flow trends prior to precipitation adjustment for this 

station with no trends in total-flow volume, the increase in 

base-flow index likely corresponds to increases in base flow 

rather than decreases in runoff.

Lower Arkansas

Stations in the Lower Arkansas Basin include two stations in the Illinois River Basin, Illinois River near Tahlequah, 

Oklahoma, (station 16) and Baron Fork at Eldon, Oklahoma, 

(station 17) (figs. 26–27, 48), and Fourche Maline near Red 

Oak, Oklahoma, (station 25) which is located farther south 

than the two Illinois River stations. Most stations in the Lower 

Arkansas Basin did not have significant trends, even after 

precipitation adjustment.

Significant upward trends in base-flow volume were 

found at stations 16 and 17 prior to precipitation adjustment, 

but after adjustment no significant base-flow trends were 

detected for these stations (figs. 48–53). Station 25 did not 

have any annual or seasonal base-flow trends before or after 

precipitation adjustment. No significant trends in annual or 

seasonal total-flow volume were detected for any of the three 

stations even after precipitation adjustment (figs. 54–59).

Significant upward trends in base-flow index were 

detected for station 16 for the annual and winter-spring periods 

only (figs. 60–62). Otherwise, no station in the basin had significant base-flow index trends. The upward trend in base-flow 

index likely corresponds to increases in base flow rather than 

decreases in runoff.

Red-Sulphur

Stations in the Red-Sulphur Basin include four stations 

on three rivers that are tributaries to the Red River: Blue River 

near Blue, Oklahoma, (station 34), Kiamichi River near Big 

Cedar, Oklahoma, (station 35), Kiamichi River near Antlers, 

Oklahoma, (station 36), and Glover River near Glover, Oklahoma, (station 37) (figs. 44–48). Like the other easternmost 

basins in the study area (Neosho-Verdigris and Lower Arkansas Basins), stations in this basin had few significant trends in 

streamflow volume or base-flow index. 

A significant trend in base-flow volume was detected only 

for station 35, in which an upward trend was observed during 

the annual period only (fig. 48). After precipitation adjustment, 

no stations in the basin had significant base-flow trends (figs. 

49, 51, and 53). 

Similar to base flow, a significant upward trend in totalflow volume was detected only for station 35. However, 

station 35 had a downward trend in total-flow volume during 

the winter-spring period after precipitation adjustment (figs. 

54–59). 

Similar to base flow and total flow, a significant upward 

trend in base-flow index was detected only for station 35 

for the annual and winter-spring periods only (figs. 60–62). 

Increases in base flow rather than decreases in runoff probably caused the significance of the base-flow index trend at 

this station. However, the results of the winter-spring streamflow volume trend analysis indicate that the upward trend 
36 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

in winter-spring base-flow index is more likely caused by a 

decrease in runoff.

Annual Peak Flow Trend Analysis

Graphs showing bar charts and LOESS plots of annual 

peak flow are presented with plots of annual base-flow volume, total-flow volume, and base-flow index (figs. 11–47). 

Results of peak flow trend analysis are presented in table 10. 

A map was developed to show trends in annual peak flow (fig. 

64). 

The Kendall’s tau analysis of annual peak flow indicated 

that less than one-third of stations had significant trends. Only 

three stations (stations 4, 5, and 32), all in central Oklahoma, 

had significant upward trends. For the most part, upward 

trends in streamflow volume did not correspond to upward 

trends in peak flow with the exception of station 32 ,which 

also had upward trends in total-flow volume after precipitation adjustment, annually and seasonally. Significant trends in 

total-flow volume were not detected for stations 4 and 5. 

Significant downward trends in peak flow were detected 

at eight stations in or near western Oklahoma (near the Texas 

Panhandle or the Oklahoma Panhandle). Downward trends in 

peak flow did not always correspond to trends in total-flow 

volume. Only four stations with downward trends in peak 

flow (6, 7, 8, and 21) also had downward trends in total-flow 

volume, annually or seasonally.

Washita River near Cheyenne, Oklahoma, (station 31) 

was the only station that had a significant downward trend in 

peak flow but had a significant upward trend in total-flow volume annually and seasonally and an upward trend in total-flow 

volume after precipitation adjustment for winter-spring water 

years. However, this station had a high base-flow index (with 

a median over 0.50) and significant upward base-flow index 

trends as well as significant upward base-flow trends (even 

after precipitation adjustment). This observation indicated 

that upward trends in base-flow volume, a large component of 

total-flow volume at this station, probably contributed to the 

upward trend in total flow; whereas, runoff and peak flow may 

have decreased with time.

Number of Extreme Low-Flow Days Trend 

Analysis

Bar charts showing the number of days where streamflow was zero or less than 1 ft3

/s were created for 20 stations 

where 10 percent or more of the years in the analysis period 

for annual or seasonal water years had at least 1 or more days 

that met this criterion (table 11, figs. 65–84, back of report). 

A LOESS plot also was shown with bar charts if at least 30 

percent of the years during the analysis period (annual or 

seasonal) had at least 1 or more days where streamflow was 

zero or less than 1 ft3/s. Table 11 lists the percent of years in 

the analysis period for each station where annual or seasonal 

number of extreme low-flow days were equal to at least 1 

day. Table 11 also lists the percent of extreme low-flow days 

in the analysis (annually and seasonally). Fewer than half of 

the stations analyzed in this report had enough days that met 

this streamflow criterion for LOESS lines to be developed or 

trends to be calculated. 

Results of trend analysis of the number of extreme lowflow days are presented in table 12 and figures 85–87 (back of 

report). In table 12, a negative tau denotes a negative trend in 

the number of days of extreme low flow and indicates that low 

flow may be increasing, whereas a positive tau indicates that 

low flow may be decreasing. A majority of stations could not 

be analyzed for trends because they did not have a substantial 

number of days where streamflow met these criteria. For trend 

analysis of the number of zero-flow days, 12 stations were 

analyzed for annual water years, 5 stations were analyzed for 

winter-spring water years, and 11 stations were analyzed for 

summer-autumn water years. For trend analysis of the number 

of days where streamflow was less than 1 ft3/s, 17 stations 

were analyzed for annual water years, 8 stations were analyzed 

for winter-spring water years, and 15 stations were analyzed 

for summer-autumn water years (table 12).

Significant trends in the number of extreme low-flow 

days were downward in direction for most stations. Where 

analyzed, most stations that had significant trends in the number of days where streamflow was less than 1 ft3

/s also had 

significant trends in the number of zero-flow days that were 

in the same direction. Of 17 stations analyzed for the annual 

period, 7 stations had significant downward trends in the 

number of days less than 1 ft3/s (5 of which also had significant downward trends in the number of zero-flow days and 2 

of which could not be analyzed for the number of zero-flow 

days). Of eight stations analyzed for the winter-spring period, 

four stations had significant downward trends in the number 

of days less than 1 ft3/s (three of which also had significant 

downward trends and one of which did not have significant 

trends in the number of zero-flow days, and one of which 

could not be analyzed for the number of zero-flow days). Of 

15 stations analyzed for the summer-autumn period, 6 stations 

had significant downward trends in the number of days less 

than 1 ft3/s (4 of which also had significant downward trends 

in the number of zero-flow days and two of which could not 

be analyzed for the number of zero-flow days). Cimarron 

River near Kenton, Oklahoma, (station 6) had a significant 

upward trend in extreme low-flow days (except for the number of zero-flow days for the winter-spring period where no 

significant trends were detected); Kiamichi River near Antlers, 

Oklahoma, (station 36) had a significant upward trend for the 

number of days where streamflow was less than 1 ft3/s for the 

annual period only. Caution needs to be taken with interpretation of the trends at station 36 because the start of the analysis 

period was during the wet period, 1980–2000, which may 

have resulted in the significant upward trend in the number of 

days where streamflow was less than 1 ft3/s.

Stations with significant upward or downward trends in 

the number of extreme low-flow days might be expected to 

have significant downward or upward trends in streamflow 
Trends in Base Flow, Total Flow, and Base-Flow Index 37 Results of Kendall’s tau trend analyses of annual peak flow at selected streamflow-gaging stations in and near Oklahoma. Figure 64. 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarron

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level )

State border

#

32

Streams

ANNUAL PEAK-FLOW TRENDS

Albers Equal-Area Conic Projection.

North American Datum 1983.

Downward trend, not significant

36

#

Upward trend, not significant

#

24

Numbers correspond to tabl e 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

Significant downward trend(95-percent confidence level )

21

#
38 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 10. Results of trend analyses of annual peak flows for 37 selected streamflow-gaging stations in and near Oklahoma. —

Continued

[USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability level; ft3/s, cubic feet per second; the shaded values are 

statistically significant at the 0.05 level, green shade indicates a statistically significant upward trend, orange shade indicates a statistically significant downward trend]

Station number 

(fig. 1) USGS station ID Median annual peak flow (ft3/s)

Trend slope 

([ft3/s]/year)

Trend slope 

(percent of 

median)

Kendall’s tau p-value

1 07146500 25,550 121 0.47 0.093 0.273

2 07151000 15,500 115 0.74 0.143 0.088

3 07152000 22,550 113 0.50 0.111 0.170

4 07152500 52,750 1134 2.15 0.25 0.046

5 07153000 5,870 100 1.70 0.242 0.027

6 07154500 4,020 -105 -2.61 -0.322 <0.001

7 07156900 686 -37 -5.40 -0.405 <0.001

8 07158000 14,100 -333 -2.36 -0.411 <0.001

9 07159100 25,900 -336 -1.30 -0.118 0.327

10 07161450 41,900 113 0.27 0.054 0.514

11 07171000 31,650 137 0.43 0.080 0.461

12 07172000 17,900 129 0.72 0.125 0.237

13 07188000 36,100 68.4 0.19 0.047 0.576

14 07191000 13,600 42.5 0.31 0.062 0.482

15 07191220 3,900 26.7 0.68 0.068 0.509

16 07196500 19,800 2.6 0.01 0.001 0.992

17 07197000 15,650 83.8 0.54 0.084 0.345

18 07228500 15,500 -97 -0.63 -0.063 0.578

19 07231000 7,470 -2 -0.03 -0.007 0.958

20 07231500 47,900 -2 -0.00 -0.001 1.000

21 07234000 3,320 -153 -4.61 -0.666 <0.001

22 07238000 2,880 -67 -2.33 -0.378 <0.001

23 07242000 11,400 0.0 0.00 0.000 1.000

24 07243500 8,350 -1 -0.01 -0.001 1.000

25 07247500 3,430 -48 -1.38 -0.191 0.074

26 07300500 10,200 -207 -2.03 -0.388 <0.001

27 07301500 6,140 -100 -1.63 -0.292 <0.001

28 07311500 8,500 -34 -0.40 -0.036 0.753

29 07315700 5,115 70.6 1.38 0.129 0.198

30 07316000 47,300 -92 -0.19 -0.037 0.668

31 07316500 580 -17 -3.01 -0.231 0.021

32 07326500 4,700 69.2 1.47 0.213 0.040
Trends in Base Flow, Total Flow, and Base-Flow Index 39

Table 10. Results of trend analyses of annual peak flows for 37 selected streamflow-gaging stations in and near Oklahoma. —

Continued

[USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability level; ft3/s, cubic feet per second; the shaded values are 

statistically significant at the 0.05 level, green shade indicates a statistically significant upward trend, orange shade indicates a statistically significant downward trend]

Station number 

(fig. 1) USGS station ID Median annual peak flow (ft3/s)

Trend slope 

([ft3/s]/year)

Trend slope 

(percent of 

median)

Kendall’s tau p-value

33 07331000 30,000 145 0.48 0.088 0.389

34 07332500 8,650 20.0 0.23 0.049 0.547

35 07335700 9,260 35.0 0.38 0.040 0.714

36 07336200 27,300 -267 -0.98 -0.093 0.528

37 07337900 26,400 23.5 0.09 0.011 0.920

Table 11. Percent of period of record with extreme low-flow days for 37 selected streamflow-gaging stations. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; % Years, the percent of years for the specified water-year type where at least one day 

is greater than zero; % Days, the percent of days for the specified water-year type that are greater than zero]

Station 

no.

(fig. 1)

USGS

station

ID

Number of zero-flow days Number of days where flow is less than 1 cubic foot per 

second

Annual water 

years

Winter-spring 

water years1

Summerautumn water 

years1

Annual water 

years

Winter-spring 

water years1

Summerautumn water 

years1

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

% 

Days

1 07146500 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

2 07151000 3.0 0.2 0.0 0.0 1.5 0.4 4.5 0.3 0.0 0.0 3.0 0.8

3 07152000 2.8 0.1 0.0 0.0 2.8 0.2 13.9 0.7 4.2 0.2 9.7 1.5

4 07152500 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

5 07153000 26.8 1.4 9.8 0.4 20.0 2.7 53.7 6.4 20.0 3.1 39.0 10.9

6 07154500 94.8 25.1 74.1 14.6 84.5 39.9 100.0 55.4 100.0 51.4 100.0 61.4

7 07156900 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

8 07158000 71.8 7.6 21.1 1.1 67.6 16.6 85.9 10.4 31.0 1.9 77.5 22.2

9 07159100 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

10 07161450 0.0 0.0 0.0 0.0 0.0 0.0 2.5 0.0 1.2 0.0 0.0 0.0

11 07171000 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

12 07172000 48.9 4.3 13.3 2.2 37.8 7.1 73.3 11.0 26.7 6.9 64.4 16.6

13 07188000 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

14 07191000 0.0 0.0 0.0 0.0 0.0 0.0 59.0 4.0 16.4 1.2 59.0 7.9

15 07191220 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

16 07196500 0.0 0.0 0.0 0.0 0.0 0.0 1.4 0.0 0.0 0.0 1.4 0.1

17 07197000 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

18 07228500 12.8 0.9 0.0 0.0 12.8 2.2 15.4 1.2 0.0 0.0 15.4 2.8
40 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Table 11. Percent of period of record with extreme low-flow days for 37 selected streamflow-gaging stations. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; % Years, the percent of years for the specified water-year type where at least one day 

is greater than zero; % Days, the percent of days for the specified water-year type that are greater than zero]

Station 

no.

(fig. 1)

USGS

station

ID

Number of zero-flow days Number of days where flow is less than 1 cubic foot per 

second

Annual water 

years

Winter-spring 

water years1

Summerautumn water 

years1

Annual water 

years

Winter-spring 

water years1

Summerautumn water 

years1

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

%

Days

% 

Years

% 

Days

19 07231000 32.6 2.9 7.0 0.7 25.6 5.9 51.2 7.9 14.0 3.2 44.2 14.2

20 07231500 13.6 0.8 2.3 0.0 11.4 1.9 27.3 1.4 4.5 0.2 22.7 3.1

21 07234000 70.0 19.7 36.7 9.6 66.7 33.3 100.0 54.1 80.0 43.7 96.7 68.5

22 07238000 16.7 0.5 0.0 0.0 16.7 1.3 43.3 2.1 0.0 0.0 26.7 5.0

23 07242000 5.6 0.4 5.6 0.0 5.6 1.0 5.6 0.4 5.6 0.0 2.8 1.0

24 07243500 0.0 0.0 0.0 0.0 0.0 0.0 2.4 0.0 0.0 0.0 2.4 0.0

25 07247500 39.0 2.3 7.3 0.6 36.6 4.7 90.2 11.8 26.8 3.9 75.6 22.1

26 07300500 84.5 20.9 47.9 9.8 81.7 36.2 93.0 24.8 56.3 11.8 88.7 42.6

27 07301500 82.6 19.3 30.4 9.5 73.9 32.5 88.2 21.6 31.9 10.6 81.2 36.6

28 07311500 69.5 11.3 28.8 5.9 67.8 18.9 83.1 24.9 47.5 19.4 78.0 32.8

29 07315700 66.7 10.7 22.9 4.9 60.4 18.7 89.6 26.5 58.3 19.5 93.8 36.3

30 07316000 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

31 07316500 83.3 18.4 31.3 5.5 72.9 36.2 91.7 23.9 47.9 8.9 81.3 44.7

32 07326500 2.2 0.0 0.0 0.0 2.2 0.0 4.4 0.0 0.0 0.0 4.4 0.1

33 07331000 2.1 0.0 0.0 0.0 0.0 0.0 2.1 0.1 0.0 0.0 2.1 0.2

34 07332500 2.8 0.1 0.0 0.0 1.4 0.3 5.6 0.3 0.0 0.0 4.2 0.8

35 07335700 81.4 9.8 14.0 1.3 69.8 21.6 95.3 18.4 23.3 2.8 95.3 40.1

36 07336200 20.0 2.6 4.0 0.9 16.0 5.0 36.0 4.0 4.0 1.5 28.0 7.4

37 07337900 27.7 1.8 2.1 0.1 25.5 4.0 57.4 4.6 8.5 0.8 55.3 9.8

1

Winter-spring water years indicate that record used in analysis was only from the months of November through May and summer-autumn water years 

indicates that record used in analysis was only from the months of June through October.

Table 12. Results of Kendall’s tau trend analyses on the number of extreme low-flow days for 17 selected streamflow-gaging 

stations in and near Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; --, trend analysis 

was not performed; the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant downward trend, orange shade indicates a statistically significant upward trend; --, trend test not performed]

Station 

no. 

(fig. 1)

USGS

station

ID

Numer of zero-flow days Number of days where flow is less than 1 cubic foot 

per second

Annual water 

years

Winter-spring 

water years1

Summerautumn water 

years1

Annual water 

years

Winter-spring 

water years1

Summer-autumn 

water years1

Tau p-value Tau p-value Tau p-value Tau p-value Tau p-value Tau p-value

5 07153000 -- -- -- -- -- -- -0.26 0.010 -- -- -0.22 0.019
Groundwater Level Trend Analysis 41

volume, respectively. However, stations with significant 

trends in the number of extreme low-flow days did not always 

correspond to trends in streamflow volume. Little River near 

Sasakwa, Oklahoma, Deep Creek near Randlett, Oklahoma, 

and Kiamichi River near Antlers, Oklahoma, (stations 19, 

28, and 36, respectively; stations 19 and 36 are regulated by 

water-supply reservoirs) had significant downward trends in 

the number of extreme low-flow days annually or seasonally 

but did not have any significant upward trends in streamflow 

volume. However, most stations that had downward trends 

in the number of days where streamflow met these criteria 

also had upward trends in base-flow index, although not all 

of those base-flow volume or base-flow index trends were 

significant. 

Groundwater Level Trend Analysis

Graphs showing LOESS plots of winter groundwater 

levels for 35 wells that were analyzed for trends are presented 

in figures 88–96 (back of report). Results of trend analyses 

for winter groundwater levels are presented in table 13. A 

map was developed to display spatial patterns in trend results 

for winter groundwater levels (fig. 97). The groundwater 

levels used represent the depth below ground surface of the 

water table. Therefore, a negative Kendall’s tau represents an 

increase in the groundwater-level elevation (closer to surface). 

Figure 97 uses upward arrows to indicate an upward trend in 

groundwater level (a negative Kendall’s tau), and a downward 

arrow to indicate a downward trend in groundwater level 

(positive Kendall’s tau).

Groundwater levels in 25 of the 35 groundwater wells 

used in the water-level trend analysis had significant trends, 

18 of which were significant upward trends. Results of this 

analysis were very similar to those reported by Tortorelli and 

others (2005). Significant downward trends in groundwater 

levels were detected for seven wells. Five of these seven 

wells were mostly located in the Oklahoma Panhandle. The 

remaining two wells with significant downward trends in 

groundwater levels included one well in the Edwards-Trinity 

Table 12. Results of Kendall’s tau trend analyses on the number of extreme low-flow days for 17 selected streamflow-gaging 

stations in and near Oklahoma. —Continued

[no., number; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; --, trend analysis 

was not performed; the shaded values are statistically significant at the 95 percent confidence level, green shade indicates a statistically significant downward trend, orange shade indicates a statistically significant upward trend; --, trend test not performed]

Station 

no. 

(fig. 1)

USGS

station

ID

Numer of zero-flow days Number of days where flow is less than 1 cubic foot 

per second

Summer- Annual water Winter-spring autumn water years water years1

years1

Annual water Winter-spring Summer-autumn 

years water years1 water years1

Tau p-value Tau p-value Tau p-value Tau p-value Tau p-value Tau p-value

6 07154500 0.27 0.003 0.03 0.715 0.28 0.002 0.36 <0.001 0.30 0.001 0.32 <0.001

8 07158000 0.06 0.485 -- -- 0.07 0.396 0.01 0.909 -0.08 0.251 0.05 0.500

12 07172000 -0.12 0.221 -- -- -0.16 0.087 -0.09 0.386 -- -- -0.15 0.154

14 07191000 -- -- -- -- -- -- 0.05 0.574 -- -- 0.05 0.531

19 07231000 -0.19 0.034 -- -- -- -- -0.32 0.002 -- -- -0.30 0.002

21 07234000 -0.05 0.717 -0.12 0.290 -0.05 0.729 0.03 0.830 -0.04 0.774 0.17 0.205

22 07238000 -- -- -- -- -- -- -0.23 0.048 -- -- -- 0.084

25 07247500 0.05 0.635 -- -- 0.10 0.290 0.02 0.866 -- -- 0.04 0.700

26 07300500 -0.32 <0.001 -0.38 <0.001 -0.25 0.002 -0.28 0.001 -0.39 <0.001 -0.18 0.024

27 07301500 -0.37 <0.001 -0.29 <0.001 -0.33 <0.001 -0.36 <0.001 -0.30 <0.001 -0.32 <0.001

28 07311500 -0.26 0.003 -- -- -0.26 0.003 -0.20 0.029 -0.19 0.024 -0.17 0.049

29 07315700 -0.08 0.399 -- -- -0.13 0.183 -0.19 0.062 -0.12 0.209 -0.18 0.068

31 07316500 -0.44 <0.001 -0.24 0.004 -0.42 <0.001 -0.44 <0.001 -0.26 0.005 -0.40 <0.001

35 07335700 0.14 0.175 -- -- 0.15 0.145 0.07 0.523 -- -- 0.08 0.464

36 07336200 -- -- -- -- -- -- 0.29 0.020 -- -- -- 0.097

37 07337900 -- -- -- -- -- -- -0.14 0.166 -- -- -0.16 0.108

1

Winter-Spring water years indicate that record used in analysis was only from the months of November through May and summer-autumn water years 

indicates that record used in analysis was only from the months of June through October.
42 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 Table 13. Results of Kendall’s tau trend analyses of annual winter groundwater levels for entire period of record in 35 selected ground water wells in Oklahoma. —Continued [no., number; OWRB, Oklahoma Water Resources Board; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; WY, water year; feet/yr, feet below land surface per year; A&T, Alluvial and Terrace Deposits; shading indicates trend significance at 95-percent confidence level (probability value less than or equal to 0.05), green shade indicates a statistically significant downward trend in depth of water below land surface, orange shade indicates a statistically significant upward trend in depth of water below land surface, Principal aquifer or geologic unit data from USGS National Water Information System, http://waterdata.usgs.gov/nwis] Well no. (fig 97) OWRB well number USGS station ID County Principal aquifer or geologic unit in which well is completed Use Start-end WY Number of miss- ing years Kend- all’s tau p-value Trend slope (feet/yr)

1 2300 364620102282001 Cimarron High Plains1 Irrigation 1967-2008 2 0.764 <0.001 1.322 2074 363110102064001 Cimarron High Plains1 Irrigation 1967-2008 2 0.883 <0.001 1.113 9695 363405101390401 Texas High Plains1 Irrigation 1966-2008 1 0.995 <0.001 1.384 1362 365028101215901 Texas High Plains1 Irrigation 1966-2008 1 0.986 <0.001 2.765 572 365141100542101 Beaver High Plains1 Irrigation 1968-2008 2 0.741 <0.001 0.526 9031 363600100144701 Beaver High Plains1 Irrigation 1967-2007 3 -0.568 <0.001 -0.687 9436 344630099370201 Greer Blaine1 Irrigation 1951-2008 10 -0.358 <0.001 -0.388 -- 361714099315101 Woodward High Plains1 Observation 1958-2008 7 -0.568 <0.001 -0.199 9497 343913099313901 Jackson Blaine1 Irrigation 1954-2008 9 -0.293 0.004 -0.18

10 9818 342628099082401 Tillman A&T North Fork Red River1 Irrigation 1945-2008 7 -0.313 0.001 -0.16

11 9871 361610099070901 Woodward A&T North Canadian River1 Domestic 1977-2008 5 -0.356 0.01 -0.20

12 9857 363658098502601 Woods A&T Cimarron River1 Irrigation 1975-2008 9 -0.727 <0.001 -0.3313 9842 351308098395701 Washita Rush Springs1 Irrigation 1975-2008 6 -0.952 <0.001 -1.5214 9587 362716098243001 Major A&T Cimarron Terrace1 Observation 1974-2008 5 -0.271 0.037 -0.0615 9006 364837098205501 Alfalfa A&T Salt Fork Arkansas River1 Irrigation 1975-2008 9 -0.483 0.001 -0.2016 9522 360052097564801 Kingfisher A&T Cimarron River1 Domestic 1951-2007 6 -0.442 <0.001 -0.1717 9419 362650097562301 Garfield A&T Enid Isolated1 Domestic 1975-2008 6 -0.698 <0.001 -0.7818 9509 365824097272901 Kay Quaternary Alluvium2 Irrigation 1975-2008 10 -0.185 0.215 -0.0319 9608 352637097253701 Oklahoma Central Oklahoma1 Water Supply 1976-2008 7 -0.154 0.280 -0.7620 9262 350430097175501 Cleveland Central Oklahoma1 Domestic 1983-2008 5 0.371 0.020 0.3821 9424 344844096575701 Garvin Gerty Sand1 Irrigation 1975-2008 4 -0.435 0.001 -0.2322 9504 341243096534501 Johnston Edwards Trinity1 Domestic 1977-2007 4 -0.345 0.012 -0.2323 9558 352907096411001 Lincoln Ada Vamoosa1 Irrigation 1980-2008 6 -0.779 <0.001 -0.5824 -- 343457096404501 Potontoc A&T North Canadian River1 Observation 1960-2008 2 -0.149 0.142 -0.1425 9588 335621096380301 Marshall Edwards Trinity1 Domestic 1978-2007 4 0.908 <0.001 1.27
Groundwater Level Trend Analysis

43

Table 13. Results of Kendall’s tau trend analyses of annual winter groundwater levels for entire period of record in 35 selected ground water wells in Oklahoma. —Continued[no., number; OWRB, Oklahoma Water Resources Board; USGS station ID, U.S. Geological Survey station identifier; Tau, Kendall’s tau; p-value, probability value; <, less than; WY, water year; feet/yr, feet below land surface per year; A&T, Alluvial and Terrace Deposits; shading indicates trend significance at 95-percent confidence level (probability value less than or equal to 0.05), green shade indicates a statistically significant downward trend in depth of water below land surface, orange shade indicates a statistically significant upward trend in depth of water below land surface, Principal aquifer or geologic unit data from USGS National Water Information System, http://waterdata.usgs.gov/nwis]

Well OWRB Number Trend 

no. Principal aquifer or geologic Start-end Kend- well USGS station ID County Use of miss- p-value slope (fig unit in which well is completed WY all’s tau number ing years (feet/yr) 97)

26 9626 361526096084201 Osage Chanute Formation2 Domestic 1979-2008 4 -0.080 0.582 -0.16

27 9131 340135096013601 Bryan Edwards Trinity1 Domestic 1977-2008 4 -0.786 <0.001 -1.1528 9840 364919095523101 Washington Dewey Limestone2 Irrigation 1977-2008 4 -0.103 0.453 -0.0329 9841 365557095521501 Washington Wann Formation2 Domestic 1979-2008 5 -0.323 0.025 -0.1230 9602 365439095270101 Nowata Oologah Limestone2 Domestic 1979-2007 5 -0.196 0.189 -0.0731 9278 363220095132701 Craig Savanna Sandstone2 Domestic 1979-2008 5 -0.133 0.362 -0.0332 9172 355920095111001 Cherokee Roubidoux2 Domestic 1979-2008 5 -0.190 0.191 -0.0833 9672 353117095065201 Sequoyah A&T Arkansas River1 Observation 1977-2008 4 -0.492 <0.001 -0.2634 9627 365745094580101 Ottawa Boone2 Domestic 1979-2008 4 -0.062 0.675 -0.0235 9000 355742094331201 Adair Pitkin Limestone2 Domestic 1979-2008 5 -0.167 0.253 -0.17

1 Principal aquifer2 Geologic unit
44 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

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Significant upward trend(95-percent confidence level)

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31

EXPLANATION

Principal Aquifer

Edwards-TrinityArbuckle-SimpsonBlaineCentral OklahomaHigh PlainsOzarkRush SpringsAda-VamoosaAlluvium and terrace

Well numbers correspond to table 13

Albers Equal-Area Conic Projection.

North American Datum 1983.

Aquifers from Oklahoma WaterResources Board (2010)

14

s tau trend analyses of annual winter Locations of groundwater wells used in trend analyses with principal aquifer boundaries and results of Kendall’ Figure 97.

groundwater levels for entire period of record in 35 selected groundwater wells in Oklahoma.
Evaluation of Potential Causes of Trends 45

(also referred to as the Antlers) aquifer (well 25, table 13) 

and one well in the Central Oklahoma (also referred to as the 

Garber-Wellington) aquifer (well 20). Both wells were located 

in central Oklahoma. Wells with significant upward trends 

in groundwater levels were generally located in western and 

central Oklahoma with the exception of one domestic well 

in northeastern Oklahoma (well 29) and one well in eastern 

Oklahoma in the alluvial terrace aquifer of the Arkansas River 

(well 33) (fig. 97, table 13).

Evaluation of Potential Causes of 

Trends

This section includes evaluation of potential causes of 

streamflow trends, including results of trend analysis for 

precipitation, precipitation-adjusted streamflow, groundwater levels, and a summary of historic water use and watermanagement practices that may have an effect on streamflow 

trends.

Precipitation Trends

The most direct potential cause of an upward trend in 

streamflow volume with time is an increase in the amount 

of precipitation. Results of the trend analysis for annual and 

seasonal precipitation indicated that all climate divisions had 

upward trends in annual precipitation since 1895 (table 2), and 

many climate divisions had statistically significant upward 

trends annually and seasonally (fig. 10). Increased precipitation likely caused higher streamflow volume, higher annual 

peak flow, and fewer number of extreme low-flow days. 

Many stations with significant upward trends in streamflow volume are located in climate divisions that had significant upward trends in annual precipitation, which indicates 

that increases in precipitation may have been the primary 

cause of upward trends in total-flow volume at these stations. 

Upward trends in annual and winter-spring total-flow volume 

also were detected at the downstream Washita River stations 

(stations 32 and 33), North Canadian River near Wetumka, 

Oklahoma, (station 23), and Canadian River at Calvin, 

Oklahoma, (station 20), but the stations are located in climate 

divisions in which significant upward trends in annual precipitation were not detected. However, these stations have large 

drainage-basin areas that partially contain climate divisions 

that had significant upward trends in total precipitation either 

annually or seasonally.

Upward trends in base-flow volume and base-flow index, 

as well as upward trends in the number of days where flow 

was zero or less than 1 ft3/s, were most commonly observed at 

stations throughout central Oklahoma, including south-central 

and west-central Oklahoma. Whereas, upward trends in baseflow index were detected in all climate divisions, significant 

upward trends in annual and seasonal precipitation were 

more commonly found in north-central Oklahoma and southcentral Kansas. These trends generally support a conclusion 

that increases in total annual or seasonal precipitation during 

the last part of the 20th century (1980-2000) contributed to 

increases in streamflow volume, increases in precipitation may 

not be the only cause of the upward trends in these streamflow 

parameters. 

LOESS plots of total annual precipitation for climate 

divisions indicate that most increases in annual precipitation 

started during the last 20 years of the 20th century. Graphs 

showing streamflow volume with time and LOESS trend 

lines indicate that, like annual precipitation (figs. 7–9, back 

of report), there was an increase in annual streamflow volume 

and base-flow index for many stations starting in the early 

1980s and extending through the year 2000 (figs. 11–47, back 

of report). Graphical trends in annual streamflow volume 

and base-flow index were detected in one, two, or all three of 

these parameters for about one-third of the stations analyzed. 

Upward trends in streamflow starting in the early 1980s also 

were reported by Tortorelli and others (2005) for many stations throughout the study area and by Garbrecht and others 

(2004) for 10 long-term stations in the Great Plains of Oklahoma (located in the central and western part of the State). 

Increases in annual precipitation starting around 1980 may 

have caused many of the significant upward trends in streamflow volume, as well as annual peak flows, and decreases in 

the number of extreme low-flow days. 

Increases in total annual or seasonal precipitation are 

not necessarily indicators of increases or decreases in rainfall 

intensity. Increases in rainfall intensity and duration could 

cause higher runoff from individual rainfall events, which 

would likely affect peak flow and may affect total flow. Karl 

and Knight (1998) reported that the number of storms and 

the amount of rainfall during intense precipitation increased 

significantly during the period 1910-1996 in the regions containing Kansas, Oklahoma, and Nebraska. However, no stations with upward trends in annual peak flow were located in 

climate divisions that had upward trends in annual or seasonal 

precipitation. Three stations that had upward trends in annual 

peak flow that were not located in a climate division that had 

an upward trend in annual or seasonal precipitation (stations 

4, 5, and 32) had drainage areas that crossed the boundaries of 

climate divisions with significant upward trends in annual or 

seasonal precipitation. 

No significant downward precipitation trends in climate 

divisions were found in western Kansas, Oklahoma, and 

Texas, where many stations had significant downward trends 

in streamflow volume and annual peak flow. This inconsistency between trends in precipitation and streamflow volume 

indicated that downward trends in streamflow and annual peak 

flow may be attributed to factors other than total precipitation 

(Tortorelli and others, 2005).
46 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Trends Adjusted for Annual or Seasonal 

Precipitation

In the previous section, upward trends in annual precipitation, especially during the wet period from 1980–2000, 

were described as a likely cause of significant upward trends 

in streamflow volume and base-flow index for many stations. 

The results from the trend analysis of precipitation-adjusted 

streamflow volume were used to analyze whether the annual 

or seasonal variation in precipitation is the likely cause of 

trends in streamflow volume. 

For example, LOESS plots for Mud Creek near Courtney, Oklahoma, (station 29, fig. 39) indicate an increase in 

streamflow volume during the wet period (1980-2000), but a 

return to lesser streamflow volumes after that time, which may 

have been the cause of significant upward trends in base-flow 

volume during the annual and winter-spring periods. When 

precipitation adjustment was calculated, no significant trends 

for these parameters were detected. This observation indicated 

that changes in annual or winter-spring precipitation were the 

likely cause of the significant upward trends. 

LOESS plots for Washita River near Cheyenne (station 

31, fig. 41) indicate that although annual streamflow volume 

started to increase after 1980, increases in these parameters 

remained evident after the end of the wet period (the year 

2000). As expected, although precipitation adjustment generally reduced the slope of trends in streamflow volume, precipitation adjustment did not change the direction or significance 

of most trends in streamflow volume at this station. 

Whereas, LOESS plots supported the statistical results 

for station 29, stations with plots in which LOESS lines 

increased around the period of 1980 and decreased on or after 

the year 2000 did not consistently correspond to statistically 

significant trends in unadjusted base-flow or total-flow volumes that became insignificant after precipitation adjustment. 

This inconsistency may indicate a poor or complex relation 

between annual precipitation and annual streamflow volume 

that is not accounted for by a simple LOESS relation, or indicate that other factors in addition to the increase in precipitation from 1980–2000 may have caused significant upward 

trends in streamflow volume.

For the summer-autumn period, all stations that had 

significant upward trends in total-flow volume did not have 

significant trends after precipitation adjustment was calculated. This result indicated that significant upward trends in 

total-flow volume during the summer-autumn period most 

likely are caused by changes in precipitation.

Factors other than changes in annual or seasonal precipitation may have caused significant upward trends in precipitation-adjusted streamflow volume. Significant upward trends 

in precipitation-adjusted streamflow volume may be related 

to long-term changes in climate. For example, recharge of 

aquifers that contribute to surface-water flow in the drainage 

basin as a result of increases in precipitation over a long-term 

period may result in upward trends in precipitation-adjusted 

streamflow volume (see section titled “Kendall’s Tau Test 

for Streamflow Volume Adjusted for Annual Precipitation”). 

Several anthropogenic factors that may cause upward trends 

in precipitation-adjusted streamflow volume include recharge 

as a result of return flows from irrigation or other changes in 

water management practices (see section titled “Water-Use 

and Water Management Practices” for further discussion). Further evaluation of groundwater-level trends and water-management practices in these basins may reveal if upward trends 

were caused by anthropogenic or climate-related factors.

Several stations had downward trends in precipitationadjusted streamflow volume where significant trends in unadjusted streamflow volume were not observed. Two stations, 

Arkansas River near Arkansas City, Kansas, and Spavinaw 

Creek near Sycamore, Oklahoma, (stations 1 and 15, respectively) had significant downward trends in annual base-flow 

volume after precipitation adjustment. Four stations—North 

Canadian River near Seiling, Oklahoma, Salt Fork Red River 

near Mangum, Oklahoma, North Fork Red River near Carter, 

Oklahoma and Kiamichi River near Big Cedar, Oklahoma; 

stations 22, 26, 27, and 35, respectively)—had significant 

downward trends in total-flow volume (annually or seasonally) that were not significant prior to precipitation adjustment. 

Downward trends in precipitation-adjusted streamflow volume 

are likely caused by local or regional-scale anthropogenic 

alteration such as changes in water use, water-management 

practices, and in urban or agricultural development. 

Groundwater-Level Trends 

In general, wells with significant trends in groundwater levels corresponded to trends in streamflow volume at 

many stations in the Oklahoma Panhandle and western and 

south-central Oklahoma. Water-level trends cannot easily 

be compared to trends in streamflow volume because winter 

groundwater data do not reflect seasonal changes in groundwater levels and the period of record for many wells was short 

(less than 40 years).

Downward trends in groundwater levels were detected at 

7 of 35 wells analyzed (table 13, fig. 97). Five of these (wells 

1–5) completed in the High Plains aquifer were located in the 

Oklahoma Panhandle region near stations that had downward 

trends in streamflow volume (fig. 97). Declining groundwater 

levels are likely contributing to downward trends in streamflow in the Oklahoma Panhandle. The two other wells with 

significant downward trends (well 20 completed in the Lower 

Canadian Basin and Central Oklahoma aquifer and well 25 

completed in the Red-Washita Basin and Edwards Trinity 

aquifer) were not located near any stations with significant 

downward trends in streamflow volume. These wells may be 

in areas with isolated declining groundwater levels that are 

not well connected to surface-water sources (Shana Mashburn 

and Marvin Abbott, U.S. Geological Survey, oral and written 

commun., June 2009). 

Upward trends in groundwater levels were detected for 

18 of the 35 wells analyzed (table 13, fig. 97) These wells 
Evaluation of Potential Causes of Trends 47

were mostly located in south-central and western Oklahoma 

(excluding the Oklahoma Panhandle), which is the same 

region where many surface-water stations also had significant 

upward trends in base-flow volume and base-flow index (figs. 

48–53 and 60–62). Most LOESS plots for these wells indicate 

that the start of the rising groundwater levels corresponded 

to the start of the wet period, around 1980 (figs. 89–96). 

This observation indicates that increases in precipitation are 

a likely cause of upward trends in groundwater levels (from 

either short-term or long-term recharge) and upward trends in 

streamflow volume for many stations near those wells. 

Many stations with significant upward trends in baseflow volume after precipitation adjustment were located in 

or near principal aquifers where wells had significant upward 

trends in groundwater levels. Thirteen stations had significant 

upward trends in precipitation-adjusted base-flow volume for 

annual or seasonal water years (all of which also had significant upward trends in base-flow index annually or seasonally). 

Eleven of these stations (stations 2, 10, 18, 20, 23, 26, 27, 30, 

31, 32, and 33) were located on or near principal aquifers—

alluvial and terrace aquifers along the Salt Fork Arkansas, 

Cimarron, Canadian, North Canadian, North Fork Red, and 

Washita Rivers; Central Oklahoma; Blaine; Edwards-Trinity; 

Rush Springs; and Arbuckle-Simpson (fig. 98). All four stations (stations 10, 23, 32, and 33) that had significant upward 

trends in annual or seasonal precipitation-adjusted total-flow 

volume were located near aquifer boundaries (alluvial and terrace aquifers for the Cimarron, North Canadian, and Washita 

Rivers, and Blaine and Arbuckle-Simpson aquifers) and were 

not near wells with significant downward trends. Most wells 

in these aquifers had significant upward trends in groundwater 

levels, with the exception of one well in the Edwards-Trinity 

aquifer and one well in the Central Oklahoma aquifer (the two 

wells with significant downward trends that were not located 

near any stations with significant upward trends in streamflow 

volume). This observation indicates that long-term recharge of 

principle aquifers, as a result of natural recharge from precipitation or artificial recharge from irrigation activities or other 

water-management practices, may have caused significant 

upward trends in streamflow volume, especially base-flow 

volume, after precipitation adjustment. More detailed analysis 

of local groundwater and surface-water interaction would be 

helpful in determining if the rate and magnitude of recharge of 

principle aquifers has affected streamflow.

Water-Use and Water-Management Practices

Water use could not be treated directly as a variable 

in the analysis because of a lack of reliable historic records 

(Tortorelli and others, 2005). Estimates of total freshwater 

withdrawals in Oklahoma available on a 5-year basis from 

calendar year 1950 through 2005 are shown in table 14. 

Estimated total freshwater withdrawals increased by about 400 

percent from 1950 through 1975 and then decreased by about 

25 percent from 1975 to 2005 (Tortorelli, 2009). Surface-water 

sources of withdrawal (mainly for public supply) were more 

dominant in the eastern half of Oklahoma and groundwater 

sources of withdrawal (mainly for irrigation) were more dominant in the western half of Oklahoma, including the Oklahoma 

Panhandle (Tortorelli, 2009). 

Withdrawals for irrigation increased by about 500 percent 

from 1950 through 1975 and then decreased by about 55 

percent from 1975 to 2005. The same pattern can be observed 

in the groundwater-source category (where irrigation is the 

largest percentage of groundwater use in Oklahoma), which 

increased from 1950 to 1975 by about 650 percent and then 

decreased by about 55 percent from 1975 to 2005. The 

decrease in irrigation withdrawals on a statewide basis since 

1975 may have been caused by adoption of more efficient 

irrigation practices such as sprinkler irrigation systems and 

less reliance on surface or flood application to irrigated land 

(Tortorelli, 2009). Decreases in groundwater withdrawal and 

irrigation water use may explain some upward trends in baseflow volume and base-flow index in many stations in western Oklahoma, excluding the Oklahoma Panhandle, where 

downward trends in streamflow volume for stations are not 

explained by this water-use trend. 

A likely cause of downward trends in streamflow is from 

long-term declines in groundwater levels from groundwater 

use (Sophocleous, 1998). Large declines in groundwater levels 

because of irrigation in the Oklahoma Panhandle (Upper 

Cimarron RiverBasin and upper part of the North Canadian 

River Basin) probably have contributed to decreases in streamflow in this area. Decreases in streamflows in the Beaver/

North Canadian River Basin (the upper part of the North 

Canadian River Basin) have been attributed to depletion of 

groundwater in the High Plains aquifer (Wahl and Tortorelli, 

1997; McGuire, 2009). Increases in streambed infiltration may 

have developed as a result of declines in groundwater levels, 

which cause the regional water table to decline below the 

streambed (Angelo, 1994; Wahl and Tortorelli, 1997), and may 

reduce base flow and total flow. 

The Upper Cimarron Basin has the highest percentage 

of surface-water use for irrigation (Tortorelli, 2009). Surfacewater diversions for irrigation also have been noted in the historic station record for stations in the Upper Cimarron Basin, 

at Cimarron River near Kenton and Cimarron River near 

Forgan (stations 6 and 7) (Lewis and Esralew, 2009). Direct 

surface-water diversions can reduce base flow, total flow, and 

peak flows, and possibly increase the number of extreme lowflow days as determined by the time of year when these occur. 

Downward annual and seasonal trends in these parameters 

were detected for these two stations in the Upper Cimarron 

Basin. A significant downward trend in annual base-flow index 

was observed at station 6, which indicated that total flow was 

decreasing more rapidly than base flow, and streamflow may 

have been more affected by surface-water diversions than 

groundwater withdrawals.

Water use for irrigation can affect base flow and runoff 

characteristics and in turn, affect streamflow trends depending 

upon how irrigation is applied. Irrigation returns in the river 
48 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 Table 14. Estimated total freshwater withdrawals in Oklahoma by water-use category, 1950-2005. Water-use category Estimated total freshwater withdrawals (million gallons per day)1,2 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Total withdrawal 422 890 778 1,225 1,473 2,108 1,719 1,268 1,418 1,775 1,769 1,589 Public supply 140 185 206 224 262 340 306 520 515 567 675 646 Rural domestic and livestock 70 50 59 72 81 99 93 31 171 176 193 187 Irrigation 180 225 274 364 819 1,160 870 445 601 864 717 495 Industrial, commercial 3 32 430 239 565 311 509 450 272 131 168 184 75 Source of water Ground 165 280 299 380 859 1,234 954 561 659 954 771 570 Surface 257 610 479 845 614 874 765 707 760 821 997 1,019

1 Estimates of total freshwater withdrawals from Tortorelli and others (2005).2 2005 estimates of total freshwater withdrawals from Tortorelli (2009).3 Includes thermoelectric power except 1950.
Evaluation of Potential Causes of Trends 49

basin can increase recharge and result in upward trends in 

streamflow (Luckey and Becker, 1999). Irrigation diversions 

and reduction in groundwater supply can reduce streamflow 

volume and potentially reduce the magnitude of peak flows in 

the basin (Wahl and Tortorelli, 1997; Tortorelli, 2005). 

Surface-flow characteristics for stations in the Red Headwaters Basin, which supplies water to Lugert-Altus Irrigation 

District, has shifted from streamflow dominated by runoff to 

streamflow dominated by base flow (annual base-flow index 

over 0.5). This shift is indicated by the upward trends in baseflow volume, base-flow index, and the number of extreme 

low-flow days, and by the downward trends in total-flow 

volume after precipitation adjustment and peak flow. Irrigation makes up 83 percent of all surface-water use in this basin 

(Tortorelli, 2009). The observed shift in surface-flow characteristics may be a result of increases in application of irrigation 

water from surface-water sources, which can reduce total-flow 

volume and peak flow but increase base-flow volume because 

of an increase in artificial recharge from irrigation returns 

(Luckey and Becker, 1999).

A similar observation also can be noted at station 31, 

Washita River near Cheyenne, which is located in the RedWashita Basin, but has a large percentage of drainage area 

overlying the High Plains aquifer (fig. 1) and is dominated by 

base flow (fig. 41). This station had upward trends in baseflow index and streamflow volume (base flow increased faster 

than total flow), an upward trend in extreme low flow, and a 

downward trend in peak flow. The primary source of irrigation water in the High Plains aquifer is from groundwater (and 

groundwater is the dominant source for irrigation water use), 

although recent data indicate that groundwater withdrawals 

for irrigation may have declined from this aquifer since 1995 

(Tortorelli, 2009, p. 26). Local groundwater levels mostly 

have remained stable or risen in this aquifer upgradient from 

this station since before 1950 (McGuire, 2009). Increases in 

total flow and greater percentages of base flow as a part of 

total flow (increases in base-flow index) at this station may 

be attributed to an increase in efficient agricultural practices 

that tend to artificially enhance recharge from precipitation 

and irrigation returns, and decrease the amount of withdrawals required for irrigation (Luckey and Becker, 1999; Smith 

and Wahl, 2003; Tortorelli, 2009). Artificial recharge from 

irrigation returns and a reduction in the rate of groundwater 

withdrawal also may contribute to an upward trend in baseflow volume and base-flow index at this station.

Surface-water supply for livestock may affect streamflow trends because livestock water supply serves to reduce 

surface runoff and reduces peak flows (Wahl and Tortorelli, 

1997), and may induce recharge and increase base flow and 

base-flow index (Luckey and Becker, 1999; Smith and Wahl, 

2003). Water use for livestock has been steadily increasing 

throughout Oklahoma since 1950 (table 14). The Red-Washita 

Basin has the largest total withdrawals for livestock operations and the largest increase in the amount of withdrawal for 

livestock (from 1990–2005) for any major river basin in the 

State (Tortorelli, 2009). Upward trends in base-flow volume 

and base-flow index were detected for many stations in this 

basin. For the upper part of the North Canadian River Basin 

(located in the Oklahoma Panhandle), documentation has been 

made of increases in the number of livestock ponds (Wahl 

and Tortorelli, 1997), which may be one of several factors 

that resulted in reduced streamflow and downward trends in 

streamflow volume and peak flow for station 31. 

Surface-water sources for public supply (including commercial and industrial uses) are less likely to affect long-term 

trends in streamflow because these sources mostly are reservoirs in which releases are managed. Most surface-water 

withdrawals for public supply have increased, especially in 

river basins in central and eastern Oklahoma, which may correspond to an increase in population in Oklahoma (Tortorelli, 

2009). No substantial correlation could be identified between 

significant trends in streamflow and trends in surface-water 

withdrawals for public supply.

Other types of water-management practices may have an 

effect on streamflow trends. Many stations used in this report 

were affected by floodwater retarding (FWR) structures. FWR 

structures tend to have the most substantial effect on streamflow by reducing flood peak discharge (Tortorelli, 1997). 

Similar to livestock ponds, these structures may have an effect 

on low flow as infiltration is increased as runoff is held behind 

the retention dam. This retention and infiltration may result in 

artificial recharge, which can augment base flow for stations 

affected by these conditions (Tortorelli and Bergman, 1985; 

R.L. Tortorelli, oral and written commun., August 2009). 

Increases in recharge from long-term increases in precipitation 

during the wet period (1980–2000) artificially enhanced by the 

presence of FWR structures may explain some upward trends 

in streamflow volume that are still significant after adjustment 

for annual or seasonal precipitation, and may explain some 

significant upward trends in base-flow index.

A spatial correlation was observed between the location of stations in southwestern and central Oklahoma that 

had significant upward trends in annual and winter-spring 

base-flow volume (before and after precipitation adjustment) 

and the location of floodwater retarding structures. Figure 98 

highlights 8-digit hydrologic units (HU) where more than 10 

percent of the drainage area was affected by FWR structures. 

This highlighted region is similar to the spatial pattern in stations with significant upward precipitation-adjusted base-flow 

trends observed for central and southwestern Oklahoma (fig. 

63), especially in the Red-Washita Basin. Streamflow at some 

stations with large drainage basins that were not substantially 

affected by FWR structures (as a total percent of the drainage area) may be influenced by FWR structures that are near 

the station (fig. 98). These stations included Cimarron River 

near Ripley, Oklahoma, (station 10), North Canadian River 

near Wetumka, Oklahoma, (station 23), and Canadian River 

at Calvin, Oklahoma, (station 20). Significant upward trends 

in base-flow index and upward trends in annual or seasonal 

precipitation-adjusted streamflow volume were detected at all 

three stations. 
50 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008 Albers Equal-Area Conic Projectio n North American Datum 1983 KANSAS TEXAS

ARKANSAS

MISSOURI COLORADO

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EXPLANATION

Eight-digit Hydrologic Unit (HU)Eight-digit HU where 10 percent or more of the drainage-area isupstream from FWR structures

State boundaryStream

! FWR structures (U.S. Geological

Survey , 2009; Smith andEsralew, 2010)

2

10

5

3

20

33

32

31

2726

23

18

# Streamflow gaging-station and

number with significant upward precipitation-adjusted trend inbase flow for either annual orseasonal water years

20

!

Locations of floodwater retarding (FWR) structures relative to eight-digit hydrologic unit boundaries and streamflow-gaging stations with significant upeard Figure 98.

trends in precipitation-adjusted base-flow volume.
Summary 51

Even though a spatial correlation was observed between 

areas affected by FWR structures and regions where many 

stations had significant upward trends in base-flow index and 

streamflow volume, significant upward trends in annual or 

seasonal precipitation-adjusted base-flow volume were only 

detected for four out of eight stations that were regulated 

by FWR structures (table 1): Black Bear Creek at Pawnee, 

Oklahoma, (station 5), and Washita River near Cheyenne, at 

Anadarko, and near Dickson, Oklahoma, (stations 31, 32, 

and 33 respectively). Significant upward trends in annual or 

seasonal base-flow index also were detected for these stations 

in addition to Little River near Sasakwa, Oklahoma, (station 19). No significant upward trends in annual or seasonal 

precipitation-adjusted base-flow volume were detected for 4 

stations substantially affected by FWR structures: Caney River 

near Elgin, Oklahoma, (station 12), Little River near Sasakwa, 

Oklahoma, (station 19), Deep Fork near Beggs, Oklahoma 

(station 24), and Fourche Maline near Red Oak, Oklahoma, 

(station 25). No significant base-flow index trends were 

detected for stations 12, 24, and 25. Streamflow at station 24 

is moderately regulated by a water-supply reservoir (table 1), 

which also may affect base-flow index trends.

The inconsistency in the results of the trend analysis for 

stations substantially affected by FWR structures indicates that 

FWR structures may not be the dominant or an important factor contributing to significant trends in precipitation-adjusted 

streamflow volume. Rates of artificial recharge as a result of 

FWR structures also may be affected by infiltration capacity, 

soil permeability, and other local geologic characteristics of 

the drainage basins. Further investigation into the effects of 

FWR structures and other regulation on base flow and baseflow index for stations with different drainage-basin characteristics may help to identify potential sources of natural and 

artificial recharge, but was beyond the scope of this report.

Summary

The U.S. Geological Survey, in cooperation with the 

Oklahoma Water Resources Board, investigated trends in base 

flow, total flow, and base-flow index at selected streams in 

and near Oklahoma on an annual and seasonal (winter-spring, 

and summer-autumn) basis. Also included in the statistical 

evaluation were trends in annual and seasonal precipitation for 

12 climate divisions in the study area, annual peak flow for 

selected stations, the number of days where streamflow was 

zero or less than one 1 cubic foot per second, both annually 

and seasonally, and annual winter groundwater levels for wells 

throughout the study area. These parameters were selected 

because these parameters are useful for comprehensive waterresources management, especially for flood control, low-flow 

permitting, and wastewater management.

Thirty-seven stations were selected for trend analysis. 

Streamflow at most stations was unregulated or was affected 

by moderate regulation. Most stations had a minimum length 

of continuous daily-mean streamflow record of at least 40 

years through water year 2008 without substantial record gaps. 

For stations with moderately regulated streamflow, the regulated period of record was analyzed.

To assist with visual identification of potential trends, bar 

charts and LOESS lines were developed for annual base-flow 

volume, total-flow volume, base-flow index, annual and seasonal precipitation, annual peak flow, and winter groundwater 

levels. Bar charts and LOESS lines also were developed for 

the number of days where streamflow was zero or less than 1 

cubic foot per second for selected stations. 

Kendall’s tau trend analysis was used to evaluate statistical trends in precipitation, streamflow, and groundwater levels. 

Precipitation-adjusted trends using LOESS regressions and 

Kendall’s tau were calculated for annual and seasonal baseflow and total-flow volumes to identify the presence of underlying trends in streamflow volume that were not associated 

with annual or seasonal variations in precipitation. Kendall’s 

tau was used to test trends on error residuals from LOESS 

regressions of annual or seasonal precipitation and streamflow 

volume. Significant trends in precipitation-adjusted streamflow 

volume may be caused by withdrawals and diversions, irrigation returns, or long-term recharge from underlying aquifers.

In general, climate divisions with significant upward 

trends in precipitation (either annually or seasonally) were 

detected in central Oklahoma and central and southeastern 

Kansas. More climate divisions had statistically significant 

upward trends in total precipitation for annual water years than 

in winter-spring or summer-autumn water years.

Significant trends in annual or seasonal base-flow volume 

were detected for 22 stations, 19 of which had upward trends. 

Significant trends in annual or seasonal total-flow volume 

were detected for 14 stations, 9 of which had upward tends. 

Many stations that had significant upward trends in annual or 

seasonal total-flow volume also had significant upward trends 

in base-flow volume for the same period. Precipitation adjustment changed the results (significance only or significance and 

direction) of annual or seasonal trends in unadjusted base-flow 

volume for 12 stations and in unadjusted total-flow volume for 

13 stations. 

Significant trends in annual or seasonal base-flow index 

were detected for 25 stations, 23 of which had upward trends. 

Eighteen stations that had significant upward trends in annual 

or seasonal base-flow index also had significant upward trends 

in base-flow volume and no significant downward trends in 

total-flow volume during the same period, which indicated 

that upward trends in base-flow index were likely driven by 

increases in base-flow volume at these stations. 

Maps were used to evaluate spatial patterns in stations 

with significant trends. Trend results were highly variable 

throughout the State. However, some recurring patterns in 

locations of stations with similar trend results were detected. 

In general, significant downward trends in base-flow and 

total-flow volume were detected for the three stations in the 

Oklahoma Panhandle (including stations in the Upper Cimarron River Basin and upper part of the North Canadian River 
52 Trends in Base Flow, Total Flow, and Base-Flow Index of Selected Streams in Oklahoma through 2008

Basin). Significant upward trends in annual or seasonal baseflow volume before and after precipitation adjustment were 

detected for 12 stations in central, southwestern, and southcentral Oklahoma (including stations in the Red Headwaters, Red-Washita, Lower Canadian, lower part of the North 

Canadian, and Arkansas-Keystone Basins). No clear regional 

patterns were detected for stations with trends in unadjusted or 

precipitation-adjusted total-flow volume in central and western 

Oklahoma (excluding the Oklahoma Panhandle). 

Prior to precipitation adjustment, significant upward 

trends in annual or seasonal base-flow volume were detected 

for four stations in the eastern half of Oklahoma (including 

stations in the Neosho-Verdigris, Lower Arkansas, and RedSulphur Basins) and a significant upward trend in total-flow 

volume was detected for one station for the winter-spring 

period. After precipitation adjustment, no stations in this 

region had significant upward trends in base-flow or total-flow 

volume, one station had significant downward trends in annual 

base-flow volume, and one station had significant downward 

trends in winter-spring total-flow volume. Significant upward 

trends in annual or seasonal base-flow index were detected for 

three stations in this region.

The Kendall’s tau analysis of annual peak flow indicated 

that less than one-third of stations evaluated in this report had 

significant trends. Significant downward trends in annual peak 

flow were detected for eight stations in or near western Oklahoma (near the Texas Panhandle or the Oklahoma Panhandle). 

Direction of significant trends in annual peak flow did not 

consistently correspond to trends in total-flow volume. 

Most stations that had significant trends in the number of 

days where streamflow was zero or less than 1 cubic foot per 

second were downward in direction, which indicated increases 

in extreme low flow. A majority of stations could not be analyzed for trends because these stations did not have a significant number of days where streamflow stamet these criteria. 

Where analyzed, most stations that had significant trends in 

the number of zero-flow days also had significant trends in the 

number of days that were less than 1 cubinc foot per second 

for the same period. However, stations with significant trends 

in the number of days where streamflow was zero or less than 

1 cubic foot per second did not always correspond to trends in 

streamflow volume.

Winter groundwater levels in 25 of 35 groundwater 

wells had significant trends. Eighteen groundwater wells with 

significant upward trends in groundwater levels were located 

in western and central Oklahoma. Five of seven wells with 

significant downward trends were located in the Oklahoma 

Panhandle. Two wells with significant downward trends in 

groundwater levels were located in central Oklahoma.

Increases in annual and seasonal precipitation, especially 

for the period of 1980–2000, may have caused significant 

upward trends in annual or seasonal base-flow and total-flow 

volumes at stations where precipitation-adjustment removed 

the significant upward trends in these parameters. Factors that 

may cause upward trends in precipitation-adjusted streamflow 

volume include anthropogenic factors such as return flows 

from irrigation or changes in water-management practices, 

and climate-related factors such as recharge of aquifers that 

contribute to surface-water flow in the drainage basin (as a 

result of increases in precipitation over a long-term period). 

Downward trends in unadjusted and precipitation-adjusted 

streamflow volume are likely caused by local or regionalscale anthropogenic alteration such as water use or watermanagement practices or increases in urban or agricultural 

development. 

In general, trends in annual groundwater levels corresponded to trends in streamflow volume at many stations in 

the Oklahoma Panhandle and western and south-central Oklahoma. Two wells in central Oklahoma with significant downward trends were not located near any stations with significant 

downward trends in streamflow volume. These wells may be 

in areas with isolated declining groundwater levels that are 

not well-connected to surface-water sources. Eleven stations with significant upward trends in precipitation-adjusted 

annual and winter-spring base-flow volume were located in 

or near principal aquifers where many wells had significant 

upward trends in groundwater levels, indicating that increased 

recharge of underlying aquifers may have caused significant 

upward trends in base-flow volume and base-flow index at 

these stations.

A likely cause of downward trends in streamflow volume 

for many stations in the Oklahoma Panhandle is from longterm declines in groundwater levels from groundwater use. 

Surface-water diversions for irrigation also have been noted 

in the Upper Cimarron River Basin and likely contributed 

to significant downward trends in streamflow volume and 

annual peak flow for stations in this basin. A shift in streamflow characteristics from rivers dominated by runoff to rivers 

dominated by base flow has been observed for stations in 

the Red Headwaters Basin, possibly because of increases in 

artificial recharge from irrigation activities that can contribute 

to an upward trend in base-flow volume and base-flow index. 

Upward trends in base-flow volume, total-flow volume, and 

base-flow index for a station in the upper part of the Red 

Washita Basin may be attributed to more efficient agricultural 

practices, which can serve to reduce groundwater withdrawals 

upgradient from the drainage basin, or also may be attributed 

to an increase in irrigation returns.

Many stations used in this report were affected by floodwater-retarding structures, which may artificially recharge 

underlying aquifers and possibly augment base flow for stations affected by these conditions. A spatial correlation was 

observed between the location of stations in southwestern and 

central Oklahoma that had significant upward trends in annual 

and winter-spring base-flow volume (before and after precipitation adjustment) and the location of floodwater retarding 

structures, which indicated that these structures may be a contributing factor to recharge. However, only five stations that 

were substantially regulated by floodwater retarding structures 

also had significant upward trends in either annual or seasonal 

base-flow volume, total-flow volume, or base-flow index, 

which indicated that the local geology may influence recharge 
References Cited 53

characteristics for drainage basins affected by floodwaterretarding structures.

Acknowledgments

The authors would like to thank Robert Tortorelli, U.S. 

Geological Survey, for providing knowledge and expertise 

regarding streamflow statistics, gaging-station history, and 

water-use information. The authors would like to thank all 

U.S. Geological Survey Hydrologic Technicians, past and 

present, who have collected and processed streamflow data. 

The authors would like to thank Shana Mashburn and Marvin 

Abbott, U.S. Geological Survey, for providing their knowledge and expertise to the interpretation of groundwater data 

analyzed in this report. Finally, the authors would like to thank 

David K. Mueller, U.S. Geological Survey, for providing his 

knowledge and expertise toward selection of the methods used 

in the trend analysis. 

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Figures 55

Figures
56 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008
Figures 57

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

5

353025201510

Annual PrecipitationLOESS Trend Line

Kansas Climate Division 7

Southwest 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

5040302010

Annual PrecipitationLOESS Trend Line

Kansas Climate Division 8

South Central 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

706050403020

Annual PrecipitationLOESS Trend Line

Kansas Climate Division 9

Southeast 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

0

40302010

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 1

Panhandle 1896-2008

PR E C IPIT A T IO N, IN INC H E S

WATER YEAR

Figure 7. Annual precipitation and LOESS trend lines fro Kansas Climate Divisions 7–9 and Oklahoma Climate Division 1, water years 1896–2008 (National Oceanic and Atmospheric Administration, 2009).
58 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 605040302010 Annual Precipitation LOESS Trend Line Oklahoma Climate Division 2 North Central 1896-2008

PR E C IPIT A T IO N, IN INC H E S 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

706050403020

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 3

Northeast 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

5040302010

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 4

West Central 1896-2008

WATER YEAR

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

70605040302010

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 5

Central 1896-2008

Figure 8. Annual precipitation and LOESS trend lines for Oklahoma Climate Divisions 2–5, water years 1896–2008 (National Oceanic and Atmospheric Administration, 2009).
Figures 59

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

80706050403020

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 6

East Central 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

605040302010

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 7

Southwest 1896-2008

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

8070605040302010

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 8

South Central 1896-2008

WATER YEAR

1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005

9080706050403020

Annual PrecipitationLOESS Trend Line

Oklahoma Climate Division 9

Southeast 1896-2008

PR E C IPIT A T IO N, IN INC H E S

Figure 9. Annual precipitation and LOESS trend lines for Oklahoma Climate Divisions 6–9, water years 1896–2008 (National Oceanic and Atmospheric Administration, 2009).
60 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

120,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Arkansas River at Arkansas City, Kans.

Regulated 1943-2008

Station 1

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 11. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Arkansas River at Arkansas City, Kansas, (U.S. Geological Survey station identifier 07146500, station 1 from 

table 1), water years 1943–2008.
Figures 61

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Salt Fork Arkansas River at Tonkawa, Okla.

Regulated 1942-2008

Station 2

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 12. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Salt Fork Arkansas River at Tonkawa, Oklahoma, (U.S. Geological Survey station identifier 07151000, station 2 from 

table 1), water years 1942–2008.
62 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

250,000

500,000

750,000

1,000,000

1,250,000

1,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Chikaskia River near Blackwell, Okla.

Unregulated 1937-2008

Station 3

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 13. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Chikaskia River near Blackwell, Oklahoma, (U.S. Geological Survey station identifier 07152000, station 3 from table 1), 

water years 1937–2008.
Figures 63

1975 1980 1985 1990 1995 2000 2005 2010

0

40,000

80,000

120,000

160,000

200,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1975 1980 1985 1990 1995 2000 2005 2010

0

2,500,000

5,000,000

7,500,000

10,000,000

12,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Arkansas River at Ralston, Okla.

Regulated 1977-2008

Site 4

1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 14. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Arkansas River at Ralston, Oklahoma, (U.S. Geological Survey station identifier 07152500, station 4 from table 1), 

water years 1977–2008.
64 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

5,000

10,000

15,000

20,000

25,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000 Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Regulated 1968-2008

Station 5

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Black Bear Creek at Pawnee, Okla.

Figure 15. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Black Bear Creek at Pawnee, Oklahoma, (U.S. Geological Survey station identifier 07153000, station 5 from 

table 1), water years 1968–2008.
Figures 65

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1951-2008

Station 6

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Cimarron River near Kenton, Okla.

Figure 16. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Cimarron River near Kenton, Oklahoma, (U.S. Geological Survey station identifier 07154500, station 6 from 

table 1), water years 1951–2008.
66 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

5,000

10,000

15,000

20,000

25,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

120,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1966-2008

Station 7

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Cimarron River near Forgan, Okla.

Figure 17. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for Cimarron River near Forgan, Oklahoma, (U.S. Geological Survey station identifier 07156900, station 7 

from table 1), water years 1966–2008.
Figures 67

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

200,000

400,000

600,000

800,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Station 8

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Unregulated 1938-2008

Cimarron River near Waynoka, Okla.

Figure 18. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for Cimarron River near Waynoka, Oklahoma, (U.S. Geological Survey station identifier 07158000, station 8 

from table 1), water years 1938–2008.
68 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1970 1975 1980 1985 1990 1995 2000 2005 2010

0

25,000

50,000

75,000

100,000

125,000

150,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1970 1975 1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1974-2008

Station 9

1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Cimarron River near Dover, Okla.

Figure 19. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Cimarron River near Dover, Oklahoma, (U.S. Geological Survey station identifier 07159100, station 9 from 

table 1), water years 1974–2008.
Figures 69

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

30,000

60,000

90,000

120,000

150,000

180,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1940-2008

Station 10

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Cimarron River near Ripley, Okla.

Figure 20. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Cimarron River near Ripley, Oklahoma, (U.S. Geological Survey station identifier 07161450, station 10 from 

table 1), water years 1940–2008.
70 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

Figure 21. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Verdigris River near Lenapah, Oklahoma, (U.S. Geological Survey station identifier 07171000, station 11 from table 

1), water years 1967–2008.

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50,000

100,000

150,000

200,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

Regulated 1967-2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

Verdigris River near Lenapah, Okla.

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

Annua lTotal Flow

Annual Base Flow

LOESS Trend Line Total Flow LOESS Trend Line Base Flow 

Station 11

A NNU A L ST R E A MF L O W V O L U ME ,

IN A C R E -F E E T
Figures 71

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

120,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

150,000

300,000

450,000

600,000

750,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Regulated 1965-2008

Station 12

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Caney River near Elgin, Kans.

Figure 22. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Caney River near Elgin, Oklahoma, (U.S. Geological Survey station identifier 07172000, station 12 from table 

1), water years 1965–2008.
72 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

40,000

80,000

120,000

160,000

200,000

240,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1940-2008

Site 13

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Spring River near Quapaw, Okla.

Figure 23. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Spring River near Quapaw, Oklahoma, (U.S. Geological Survey station identifier 07188000, station 13 from 

table 1), water years 1940–2008.
Figures 73

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

200,000

400,000

600,000

800,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1948-2008

Station 14

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Big Cabin Creek near Big Cabin, Okla.

Figure 24. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for Big Cabin Creek near Big Cabin, Oklahoma, (U.S. Geological Survey station identifier 07191000, 

station 14 from table 1), water years 1948–2008.
74 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50,000

100,000

150,000

200,000

250,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1962-2008

Station 15

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Spavinaw Creek near Sycamore, Okla.

Figure 25. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for Spavinaw Creek near Sycamore, Oklahoma, (U.S. Geological Survey station identifier 07191220, 

station 15 from table 1), water years 1962–2008.
Figures 75

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

25,000

50,000

75,000

100,000

125,000

150,000

175,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

250,000

500,000

750,000

1,000,000

1,250,000

1,500,000

1,750,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1936-2008

Station 16

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Illinois River near Tahlequah, Okla.

Figure 26. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Illinois River near Tahlequah, Oklahoma, (U.S. Geological Survey station identifier 07196500, station 16 from table 1), 

water years 1936–2008.
76 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

100,000

200,000

300,000

400,000

500,000

600,000 Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Unregulated 1949-2008

Station 17

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Baron Fork at Eldon, Okla.

Figure 27. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Baron Fork at Eldon, Oklahoma, (U.S. Geological Survey station identifier 07197000, station 17 from table 1), water 

years 1949–2008.
Figures 77

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

200,000

400,000

600,000

800,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Canadian River at Bridgeport, Okla.

 Regulated 1970-2008

Station 18

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 28. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for Canadian River at Bridgeport, Oklahoma, (U.S. Geological Survey station identifier 07228500, station 

18 from table 1), water years 1970–2008.
78 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

2,500

5,000

7,500

10,000

12,500

15,000

17,500

20,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

200,000

400,000

600,000

800,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Little River near Sasakwa, Okla.

Regulated 1966-2008

Station 19

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 29. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Little River near Sasakwa, Oklahoma, (U.S. Geological Survey station identifier 07231000, station 19 from table 

1), water years 1966–2008.
Figures 79

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Canadian River at Calvin, Okla.

Regulated 1965-2008

Station 20

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 30. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Canadian River at Calvin, Oklahoma, (U.S. Geological Survey station identifier 07231500, station 20 from table 

1), water years 1965–2008.
80 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Beaver River at Beaver , Okla.

Unregulated 1938-1971

Regulated Irrigated 1979-2008

Station 21

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

Unregulated Period

Unregulated Period

Unregulated Period

Regulated Irrigation Period

Regulated Irrigation Period

Regulated Irrigation Period

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 31. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Beaver River at Beaver, Oklahoma, (U.S. Geological Survey station identifier 07234000, station 21 from table 1), 

water years 1938–2008.
Figures 81

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Base Flow

North Canadian River near Seiling, Okla.

Unregulated 1947-1971

Regulated Irrigated 1979-2008

Station 22

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

Unregulated Period

Unregulated Period Regulated Irrigation Period

Unregulated Period

Regulated Irrigation Period

Regulated Irrigation Period

LOESS Trend Line Total Flow

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Annual Base-Flow Index

Figure 32. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for North Canadian River at Sailing, Oklahoma, (U.S. Geological Survey station identifier 07238000, station 22 

from table 1), water years 1947–2008.
82 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

210,000

420,000

630,000

840,000

1,050,000

1,260,000

1,470,000

1,680,000 Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

North Canadian River near Wetumka, Okla.

Regulated 1938-2008

Station 23

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 33. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

North Canadian River near Wetumka, Oklahoma, (U.S. Geological Survey station identifier 07242000, station 23 from 

table 1), water years 1938–2008.
Figures 83

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Deep Fork near Beggs, Okla.

Regulated 1968-2008

Station 24

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 34. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Deep Fork near Beggs, Oklahoma, (U.S. Geological Survey station identifier 07243500, station 24 from table 1), water 

years 1968–2008.
84 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

5,000

10,000

15,000

20,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

40,000

80,000

120,000

160,000

200,000

240,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Fourche Maline near Red Oak, Okla.

Regulated 1966-2008

Station 25

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 35. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Fourche Maline near Red Oak, Oklahoma, (U.S. Geological Survey station identifier 07247500, station 25 from 

table 1), water years 1966–2008.
Figures 85

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

40,000

80,000

120,000

160,000

200,000

240,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Salt Fork Red River at Mangum, Okla.

Unregulated 1938-2008

Station 26

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 36. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Salt Fork Red River at Mangum, Oklahoma, (U.S. Geological Survey station identifier 07300500, station 26 from table 

1), water years 1938–2008.
86 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

15,000

30,000

45,000

60,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50,000

100,000

150,000

200,000

250,000

300,000

Annual Total Flow

Annual Base flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

North Fork Red River near Carter , Okla.

Unregulated 1938-1962, 1965-2008

Station 27

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

Missing record

Missing record

Missing record

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 37. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend 

lines for North Fork Red River near Carter, Oklahoma, (U.S. Geological Survey station identifier 07301500, 

station 27 from table 1), water years 1938–2008.
Figures 87

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Deep Red Creek near Randlett, Okla.

Unregulated 1970-2008

Station 28

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 38. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Deep Red Creek near Randlett, Oklahoma, (U.S. Geological Survey station identifier 07311500, station 28 from 

table 1), water years 1970–2008.
88 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

100,000

200,000

300,000

400,000

500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Mud Creek near Courtney , Okla.

Unregulated 1961-2008

Station 29

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 39. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Mud Creek near Courtney, Oklahoma, (U.S. Geological Survey station identifier 07315700, station 29 from table 

1), water years 1961–2008.
Figures 89

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50,000

100,000

150,000

200,000

250,000

300,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Red River near Gainesville, Texas

Regulated 1945-2008

Station 30

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 40. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Red River near Gainesville, Texas, (U.S. Geological Survey station identifier 07316000, station 30 from table 1), water 

years 1945–2008.
90 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000 Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Washita River near Cheyenne, Okla.

Regulated 1961-2008

Station 31

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 41. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Washita River near Cheyenne, Oklahoma, (U.S. Geological Survey station identifier 07316500, station 31 from 

table 1), water years 1961–2008.
Figures 91

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

10,000

20,000

30,000

40,000

50,000

60,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

300,000

600,000

900,000

1,200,000

1,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Washita River near Anadarko, Okla.

Regulated 1964-2008

Station 32

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 42. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Washita River near Anadarko, Oklahoma, (U.S. Geological Survey station identifier 07326500, station 32 from table 1), 

water years 1964–2008.
92 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

30,000

60,000

90,000

120,000

150,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Washita River near Dickson, Okla.

Regulated 1962-2008

Station 33

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 43. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Washita River near Dickson, Oklahoma, (U.S. Geological Survey station identifier 07331000, station 33 from table 1), 

water years 1962–2008.
Figures 93

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

15,000

30,000

45,000

60,000

75,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

150,000

300,000

450,000

600,000

750,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Blue River near Blue, Okla.

Unregulated 1937-2008

Station 34

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 44. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Blue River near Blue, Oklahoma, (U.S. Geological Survey station identifier 07332500, station 34 from table 1), 

water years 1937–2008.
94 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

6,000

12,000

18,000

24,000

30,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

25,000

50,000

75,000

100,000

125,000 Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Kiamichi River near Big Cedar , Okla.

Unregulated 1966-2008

Station 35

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 45. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Kiamichi River near Big Cedar, Oklahoma, (U.S. Geological Survey station identifier 07335700, station 35 from 

table 1), water years 1966–2008.
Figures 95

1980 1985 1990 1995 2000 2005 2010

0

15,000

30,000

45,000

60,000

75,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Kiamichi River near Antlers, Okla.

Regulated 1984-2008

Station 36

1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 46. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines for 

Kiamichi River near Antlers, Oklahoma, (U.S. Geological Survey station identifier 07336200, station 36 from table 1), 

water years 1984–2008.
96 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20,000

40,000

60,000

80,000

100,000

Annual Peak Flow

LOESS Trend Line

WATER YEAR

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Annual Total Flow

Annual Base Flow

LOESS Trend Line Total Flow

LOESS Trend Line Base Flow

Glover River near Glover , Okla.

Unregulated 1962-2008

Station 37

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0.0

0.2

0.4

0.6

0.8

1.0

Annual Base-Flow Index

LOESS Trend Line

A NNU A L PE A K F L O W, IN

C U BIC F E E T PE R SE C O ND

A NNU A L BA SE -F L O W IND E X

R AT IO (BA SE F L O W/TO TA L F L O W)

A NNU A L ST R E A MF L O W V O L U ME , 

IN A C R E -F E E T

Figure 47. Annual base-flow volume, total-flow volume, base-flow index, and peak flow, and LOESS trend lines 

for Glover River near Glover, Oklahoma, (U.S. Geological Survey station identifier 07337900, station 37 from table 1), 

water years 1962–2008.
Figures 97

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

35

37

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

Significant upward trend(95-percent confidence level)

State border

#

32

Streams

ANNUAL BASE-FLOW TRENDS#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

15

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

EXPLANATION

Results of Kendall’s tau trend analyses of annual base-flow volume at selected streamflow-gaging stations in and near Oklahoma. Figure 48.
98 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

ANNUAL PRECIPITATIONADJUSTED BASE-FLOW TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983l.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

28

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

a. Results of Kendall’s tau trend analyses of annual precipitation-adjusted base-flow volume at selected streamflow-gaging stations in and near Oklahom Figure 49.
Figures 99

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

WINTER-SPRING BASE-FLOW

TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent downward level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

15

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-spring base-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of winter Results of Kendall’ Figure 50.
100 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

WINTER-SPRING PRECIPITATIONADJUSTED BASE-FLOW TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

28

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-spring precipitation-adjusted base-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of winter Results of Kendall’ Figure 51.
Figures

101

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho

River

Rive r Red

Beaver

Rive r Cimarro n

River

Fork Salt

River

Arkansas

River River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

SUMMER-AUTUMN BASE-FLOW

TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant #

15

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

# #

#

# #

#

# #

#

#

##

#

# #

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-autumn base-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of summer Results of Kendall’ Figure 52.
102 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

SUMMER-AUTUMN PRECIPITATIONADJUSTED BASE-FLOW TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

28

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-autumn precipitation-adjusted base-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of summer Results of Kendall’ Figure 53.
Figures 103

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

ANNUAL TOTAL-FLOW TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

28

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

Results of Kendall’s tau trend analyses of annual total-flow volume at selected streamflow-gaging stations in and near Oklahoma. Figure 54.
104 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

32

Streams

ANNUAL PRECIPITATIONADJUSTED TOTAL-FLOW TRENDS

#

Albers Equal-Area Conic Projection. 

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

28

#

Upward trend, not significant

#

18

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

ahoma. Results of Kendall’s tau trend analyses of annual precipitation-adjusted total-flow volume at selected streamflow-gaging stations in and near Okl Figure 55.
Figures 105

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

WINTER-SPRING TOTAL-FLOW

TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

18

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-spring total-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of winter Results of Kendall’ Figure 56.
106 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

WINTER-SPRING PRECIPITATIONTOTOAL-FLOW TRENDS ADJUSTED

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

18

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-spring precipitation-adjusted total-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of winter Results of Kendall’ Figure 57.
Figures 107

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

River

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

SUMMER-AUTUMN TOTAL-FLOW

TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

36

#

Upward trend, not significant

#

18

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-autumn total-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of summer Results of Kendall’ Figure 58.
108 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

State border

Streams

SUMMER-AUTUMN PRECIPITATION

ADJUSTED TOTAL-FLOW TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

21

Downward trend, not significant

28

#

Upward trend, not significant

#

18

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

##

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-autumn precipitation-adjusted total-flow volume at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of summer Results of Kendall’ Figure 59.
Figures 109

36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

ANNUAL BASE-FLOW INDEX

TRENDS

Albers Equal-Area Conic Projection.

North American Datum 1983.

Downward trend, not significant

36

#

Upward trend, not significant

#

24

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

Results of Kendall’s tau trend analyses of annual base-flow index at selected streamflow-gaging stations in and near Oklahoma. Figure 60.
110 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 36

2

16

14

13

11

10 9

8

7

6

5

4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r

Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

WINTER-SPRING BASE-FLOW

INDEX TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trend(95-percent confidence level)

1

Downward trend, not significant

28

#

Upward trend, not significant

#

32

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-spring base-flow index at selected streamflow-gaging stations in and near Oklahoma s tau trend analyses of winter Results of Kendall’ Figure 61. .
Figures 111

36

2

16

14

13

11

10 9

8

7

6

5 4

3

20

34

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1

12

KANSAS

TEXAS

ARKANSAS

MISSOURI

0 5 025 MILES0 5 0 K ILOMETERS

36°

97°

34°

94° 103° 100°

River

Neosho River

Rive r Red

Beaver

Rive r

Cimarro n

River

Fork

Salt

River

Arkansas

River

River Ve rdigris

River

North

Canadian

Canadian

River

Washita

Deep Fork

Red

Rive r

Caneyney

15

COLORADO

EXPLANATION

Significant upward trend(95-percent confidence level)

State border

#

31

Streams

SUMMER-AUTUMN BASE-FLOW

INDEX TRENDS

#

Albers Equal-Area Conic Projection.

North American Datum 1983.

Significant downward trent(95-percent confidence level)

6

Downward trend, not significant

36

#

Upward trend, not significant

#

15

Numbers correspond to table 1

Four-digit hydrologic unit boundary

Arkansas-Keystone

NeoshoVerdigris

North

Canadian

Lower

Cimarron

Red-Washita

Red-Sulphur

Re d

Headwaters

Lower

Canadian

Lower

Arkansas

North

Canadian

Upper

Cimarron

Lower

Canadian

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

-autumn base-flow index at selected streamflow-gaging stations in and near Oklahoma. s tau trend analyses of summer Results of Kendall’ Figure 62.
112 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

20

40

60

80

100

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20

40

60

80

100

Station 3

Chikaskia River near Blackwell, Okla.

Unregulated 1937-2008

Number of days with flow less than 1 ft3/s

Number of zero flow days

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

20

40

60

80

100

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Figure 65. Number of extreme low-flow days for Chickaskia River near Blackwell, Oklahoma, (U.S. Geological 

Survey station identifier 07152000, station 3 from table 1), water years 1937–2008. (ft3

/s, cubic foot per second).
Figures 113

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

30

60

90

120

150

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

30

60

90

120

150

Number of days with flow less than 1 ft3/s

Number of zero flow days

Less than or equal to 1 LOESS Trend Line

Station 5

Black Bear Creek at Pawnee, Okla.

Regulated 1968-2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

30

60

90

120

150

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Figure 66. Number of extreme low-flow days for Black Bear Creek at Pawnee, Oklahoma, (U.S. Geological 

Survey station identifier 07153000, station 5 from table 1), water years 1968–2008. (ft3

/s, cubic foot per second).
114 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

350

400

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

350

400

Station 6

Cimarron River near Kenton, Okla.

Unregulated 1951-2008

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

350

400

Number of days with flow less than 1 ft3/s

Number of zero flow days

Zero flow days LOESS Trend Line

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Less than or equal to 1 LOESS Trend Line

Figure 67. Number of extreme low-flow days for Cimarron River near Kenton, Oklahoma, (U.S. Geological 

Survey station identifier 07154500, station 6 from table 1), water years 1951–2008. (ft3

/s, cubic foot per second).
Figures 115

Figure 68. Number of extreme low-flow days for Cimarron River near Waynoka, Oklahoma, (U.S. Geological 

Survey station identifier 07158000, station 8 from table 1), water years 1938–2008. (ft3

/s, cubic foot per second).

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

20

40

60

80

100

120

140

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20

40

60

80

100

120

140

Station 8

Cimarron River near Waynoka, Okla. 

Unregulated 1938-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

20

40

60

80

100

120

140

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S
116 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

Station 12

Caney River near Elgin, Kans. 

Regulated 1965-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Figure 69. Number of extreme flow-flow days for Caney River near Elgin, Kansas, (U.S. Geological Survey 

station identifier 07172000, station 12 from table 1), water years 1965–2008. (ft3

/s, cubic foot per second).
Figures 117

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

20

40

60

80

100

120

140

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20

40

60

80

100

120

140

Number of days with flow less than 1 ft3/s

Less than or equal to 1 LOESS Trend Line

Station 14

Big Cabin Creek near Big Cabin, Okla.

Unregulated 1948-2008

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

20

40

60

80

100

120

140

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Figure 70. Number of extreme low-flow days for Big Cabin Creek near Big Cabin, Oklahoma, (U.S. Geological 

Survey station identifier 07191000, station 14 from table 1), water years 1948–2008. (ft3

/s, cubic foot per second).
118 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

30

60

90

120

150

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

30

60

90

120

150

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Station 18

Canadian River at Bridgeport, Okla.

Regulated 1970-2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

30

60

90

120

150

COMPLETE WATER YEAR

YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

Figure 71. Number of extreme low-flow days for Canadian River at Bridgeport, Oklahoma, (U.S. Geological 

Survey station identifier 07228500, station 18 from table 1), water years 1970–2008. (ft3

/s, cubic foot per 

second).
Figures 119

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

25

50

75

100

125

150

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

25

50

75

100

125

150

Station 19

Little River near Sasakwa, Okla. 

Regulated 1966-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

25

50

75

100

125

150

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 72. Number of extreme low-flow days for Little River near Sasakwa, Oklahoma, (U.S. Geological 

Survey station identifier 07231000, station 19 from table 1), water years 1966–2008. (ft3

/s, cubic foot per 

second).
120 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

20

40

60

80

100

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

20

40

60

80

100

Station 20

Canadian River at Calvin, Okla.

Regulated 1965-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

20

40

60

80

100

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 73. Number of extreme low-flow days for Canadian River at Calvin, Oklahoma, (U.S. Geological 

Survey station identifier 07231500, station 20 from table 1), water years 1965–2008. (ft3

/s, cubic foot per 

second).
Figures 121

1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

350

400

1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

350

400

Station 21

Beaver River at Beaver , Okla.

Unregulated Irrigated 1979-2008

1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

350

400

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 74. Number of extreme low-flow days for Beaver River at Beaver, Oklahoma, (U.S. Geological Survey 

station identifier 07234000, station 21 from table 1), water years 1979–2008. (ft3

/s, cubic foot per second).
122 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

Station 22

North Canadian River near Seiling, Okla.

Unregulated Irrigated 1979-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 75. Number of extreme low-flow days for North Canadian River near Seiling, Oklahoma, (U.S. 

Geological Survey station identifier 07238000, station 22 from table 1), water years 1979–2008. (ft3

/s, cubic foot 

per second).
Figures 123

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

25

50

75

100

125

150

175

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

25

50

75

100

125

150

175

Station 25

Fourche Maline near Red Oak, Okla.

Regulated 1966-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

25

50

75

100

125

150

175

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 76. Number of extreme low-flow days for Fourche Maline near Red Oak, Oklahoma, (U.S. Geological 

Survey station identifier 07247500, station 25 from table 1), water years 1966–2008. (ft3

/s, cubic foot per 

second).
124 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

350

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

350

Site 26

Salt Fork Red River at Mangum, Okla.

07300500 Unregulated 1938-2008

Number of days with flow less than 1 ft3/s

Number of zero flow days

Less than or equal to 1 LOESS Trend Line

Zero flow days LOESS Trend Line

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

350

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 77. Number of extreme low-flow days for Salt Fork Red River at Mangum , Oklahoma, (U.S. Geological 

Survey station identifier 07300500, station 26 from table 1), water years 1938–2008. (ft3

/s, cubic foot per 

second).
Figures 125

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING(NOVEMBER - MAY)

0

50

100

150

200

250

300

350

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

350

Station 27

North Fork Red River near Carter, Okla. 

Unregulated 1938-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

350

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 78. Number of extreme low-flow days for North Fork Red River near Carter , Oklahoma, (U.S. 

Geological Survey station identifier 07301500, station 27 from table 1), water years 1938–2008. (ft3

/s, cubic 

foot per second).
126 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

Station 28

Deep Red Creek near Randlett, Okla.

07311500 Unregulated 1970-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 79. Number of extreme low-flow days for Deep Red Creek near Randlett , Oklahoma, (U.S. 

Geological Survey station identifier 07311500, station 28 from table 1), water years 1970–2008. (ft3

/s, cubic 

foot per second).
Figures 127

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

350

400

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

350

400

Station 29

Mud Creek near Courtney, Okla.

Unregulated 1961-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

350

400

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 80. Number of extreme low-flow days for Mud Creek near Courtney , Oklahoma, (U.S. Geological 

Survey station identifier 07315700, station 29 from table 1), water years 1961–2008. (ft3

/s, cubic foot per 

second).
128 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

Station 31

Washita River near Cheyenne, Okla.

Regulated 1961-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 81. Number of extreme low-flow days for Washita River near Cheyenne , Oklahoma, (U.S. 

Geological Survey station identifier 07316500, station 31 from table 1), water years 1961–2008. (ft3

/s, cubic 

foot per second).
Figures 129

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

Station 35

Kiamichi River near Big Cedar, Okla. 

Unregulated 1966-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

Zero-flow days LOESS Trend Line

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 82. Number of extreme low-flow days for Kiamichi River near Big Cedar , Oklahoma, (U.S. Geological 

Survey station identifier 07335700, station 35 from table 1), water years 1966–2008. (ft3

/s, cubic foot per 

second).
130 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

50

100

150

200

250

300

1980 1985 1990 1995 2000 2005 2010

0

50

100

150

200

250

300

Station 36

Kiamichi River ner Antlers, Okla.

Regulated 1984-2008

Number of days with flow less than 1 ft3/s

Number of zero-flow days

Less than or equal to 1 LOESS Trend Line

1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

50

100

150

200

250

300

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 83. Number of extreme low-flow days for Kiamichi River near Antlers , Oklahoma, (U.S. Geological 

Survey station identifier 07336200, station 36 from table 1), water years 1984–2008. (ft3

/s, cubic foot per 

second).
Figures 131

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

WINTER - SPRING (NOVEMBER - MAY)

0

30

60

90

120

150

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

0

30

60

90

120

150

Station 37

Glover River near Glover , Okla.

Unregulated 1962-2008

Number of days with flow less than 1 ft3/s

Number of zero flow days

Less than or equal to 1 LOESS Trend Line

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

SUMMER - AUTUMN (JUNE - OCTOBER)

0

30

60

90

120

150

COMPLETE WATER YEAR

NU MBE R O F D AY S NU MBE R O F D AY S NU MBE R O F D AY S

YEAR

Figure 84. Number of extreme low-flow days for Glover River near Glover , Oklahoma, (U.S. Geological 

Survey station identifier 07337900, station 37 from table 1), water years 1962–2008. (ft3

/s, cubic foot per 

second).
132 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

36

2

16

14

13

11

9 10

8

7

5

4

3

34

20

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

0 5025 MILES

0 50 KILOMETERS

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

EXPLANATION

State border Streams

Numbers correspond to table 1

Significant upward trend # (95-percent confidence level)

36

Significant downward trend

(95-percent confidence level)

31

# # Downward trend, not significant

37

# Upward trend, not significant

14 Streamflow-gaging station 

where trend analysis was not 

performed

34

!

TRENDS IN ANNUAL NUMBER OF DAYS 

36

2

16

14

13

11

9 10

8

7

6

5

4

3

34

20

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

#

#

#

#

#

# #

#

#

#

#

#

!

!

!

!

!

!

! !

! !

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

#

# !

#

! !

!

# !

#

!

!!

!

#!

#

#

!

!

# #

#

#

#

!

#

!

!

!

#

#

#

6

A

B

Figure 85. Results of Kendall’s tau trend analyses of the annual number of days when streamflow is (A) equal to zero cubic 

feet per second and (B) less than 1 cubic foot per second for selected streamflow-gaging stations in and near Oklahoma.
Figures 133

36

2

16

14

13

11

9 10

8

7

5

4

3

34

20

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

0 5025 MILES

0 50 KILOMETERS

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

EXPLANATION

State border Streams

Numbers correspond to table 1

Significant upward trend # (95-percent confidence level)

 6

Significant downward trend

(95-percent confidence level)

31

# # Downward trend, not significant

12

# Upward trend, not significant

25 Streamflow-gaging station 

where trend analysis was not 

performed

34

!

TRENDS IN ANNUAL NUMBER OF DAYS (NOVEMBER THROUGH MAY) 

36

2

16

14

13

11

9 10

8

7

6

5

4

3

34

20

19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

6

!

!

!

!

!

# !

!

! !

!

! !

!

!

!!

!

! !

#

!

!

!

! #

#

!

!

#

!

!

!

!

!

!

!

!

!

!

!

# !

#

! !

!

# !

!

!

!!

!

! !

#

!

!

!

# #

#

#

#

!

#

!

!

!

!

!

!

A

B

!

Figure 86. Results of Kendall’s tau trend analyses of the number of days per year during the period of November through 

May (winter-spring) when streamflow is (A) equal to zero cubic feet per second and (B) less than 1 cubic foot per second for 

selected streamflow-gaging stations in and near Oklahoma.
134 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008

36

2

16

14

13

11

9 10

8

7

5

4

3

34

20 19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

0 5025 MILES

0 50 KILOMETERS

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

EXPLANATION

State border Streams

Numbers correspond to table 1

Significant upward trend # (95-percent confidence level)

 6

Significant downward trend

(95-percent confidence level)

31

# # Downward trend, not significant

12

# Upward trend, not significant

25 Streamflow-gaging station 

where trend analysis was not 

performed

34

!

TRENDS IN ANNUAL NUMBER OF DAYS (JUNE THROUGH OCTOBER) 

36

2

16

14

13

11

9 10

8

7

6

5

4

3

34

20 19

37

35

33

32

31

30

29

28

27

26

25

24

23

22

21

18

17

1 12

KANSAS

TEXAS

A R K A NS A S MIS S O U R I

36° 

97° 

34° 

94° 

100°

R iver R ed

Caney

15

COLORADO

TEXAS

103°

6

!

!

!

!

#

# !

#

! !

!

# !

#

!

!!

!

#!

#

#

!

!

# #

#

#

#

!

#

!

!

!

#

#

#

!

!

!

!

!

# !

#

! !

!

# !

!

!

!!

!

!

#

!

!

!

# #

#

#

#

!

#

!

!

!

#

!

!

A

B

!

Figure 87. Results of Kendall’s tau trend analyses of the number of days per year during the period of June through October 

(summer-autumn) when streamflow is (A) equal to zero cubic feet per second and (B) less than 1 cubic foot per second for 

selected streamflow-gaging stations in and near Oklahoma.
Figures

135

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

120140160180200220240260

Water LevelLOESS Trend Line

Well 2300 Site 1

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

250260270280290300310320330340350

Water LevelLOESS Trend Line

Well 2074 Cimarron County Site 2

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

140150160170180190200210220230240

Water LevelLOESS Trend Line

Well 9695 Texas County Site 3

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

100120140160180200220240

80

Water LevelLOESS Trend Line

Well 1362 Texas County Site 4

D EPTH TO WA TER , IN FEET

WATER YEAR

Cimarron County

Groundwater levels and LOESS trend lines by using available periods of record for wells 1–4. Figure 88.
136 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 100 110 120 130 140 150 160 Water Level LOESS Trend Line Well 572 Beaver County Site 5 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 100 110 120 130 140 150 160 Water Level LOESS Trend Line Well 9031 Beaver County Site 6

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

102030405060

Water LevelLOESS Trend Line

Well 9436 Greer County Site 7

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

1020304050

Water LevelLOESS Trend Line

Sharon Well Woodward County Site 8

361714099315101

WATER YEAR

D EPTH TO WA TER , IN FEET

0 0

Groundwater levels and LOESS trend lines by using available periods of record for wells 5–8. Figure 89.
Figures

137

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

102030405060

Water LevelLOESS Trend Line

Well 9497 Jackson County Site 9

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

10152025303540

5

Water LevelLOESS Trend Line

Well 9818 Tillman County Site 10

1975 1980 1985 1990 1995 2000 2005 2010

1020304050

Water LevelLOESS Trend Line

Well 9871 Woodward County Site 11

1970 1975 1980 1985 1990 1995 2000 2005 2010

15202530354045

Water LevelLOESS Trend Line

Well 9857 Woods County Site 12

WATER YEAR

D EPTH TO WA TER , IN FEET

00

0

Groundwater levels and LOESS trend lines by using available periods of record for wells 9–12. Figure 90.
138 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 1970 1975 1980 1985 1990 1995 2000 2005 2010 100 12020406080 Water Level LOESS Trend Line Well 9842 Washita County Site 13 1970 1975 1980 1985 1990 1995 2000 2005 2010 1012

2468

Water LevelLOESS Trend Line

Well 9587 Major County Site 14

1970 1975 1980 1985 1990 1995 2000 2005 2010

10121416

2468

Water LevelLOESS Trend Line

Well 9006 Alfalfa County Site 15

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

10203040

Water LevelLOESS Trend Line

Well 9522 Kingfisher County Site 16

0

WATER YEAR

D EPTH TO WA TER , IN FEET

0

0

Groundwater levels and LOESS trend lines by using available periods of record for wells 13–16. Figure 91.
Figures

139

1970 1975 1980 1985 1990 1995 2000 2005 2010

102030405060

Water LevelLOESS Trend Line

Well 9419 Garfield County Site 17

1970 1975 1980 1985 1990 1995 2000 2005 2010

2428323640

Water LevelLOESS Trend Line

Well 9509 Kay County Site 18

1975 1980 1985 1990 1995 2000 2005 2010

100120140160180200220240260280

Water LevelLOESS Trend Line

Well 9608 Oklahoma County Site 19

1980 1985 1990 1995 2000 2005 2010

203040506070

Water LevelLOESS Trend Line

Well 9262 Cleveland County Site 20

WATER YEAR

D EPTH TO WA TER , IN FEET

Groundwater levels and LOESS trend lines by using available periods of record for wells 17–20. Figure 92.
140 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 1970 1975 1980 1985 1990 1995 2000 2005 2010 50556065707580 Water Level LOESS Trend Line Well 9424 Garvin County Site 21 1975 1980 1985 1990 1995 2000 2005 2010 12162024283236

8

Water LevelLOESS Trend Line

Well 9504 Johnston County Site 22

1975 1980 1985 1990 1995 2000 2005 2010

404550556065707580

Water LevelLOESS Trend Line

Well 9558 Lincoln County Site 23

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

100110120130140

60708090

Water LevelLOESS Trend Line

Fittstown Well Pontotoc County Site 24

343457096404501

D EPTH TO WA TER , IN FEET

WATER YEAR

Groundwater levels and LOESS trend lines by using available periods of record for wells 21–24. Figure 93.
Figures

141

1975 1980 1985 1990 1995 2000 2005 2010

100110120130140150160

Water LevelLOESS Trend Line

Well 9588 Marshall County Site 25

1975 1980 1985 1990 1995 2000 2005 2010

1020304050

Water LevelLOESS Trend Line

Well 9626 Osage County Site 26

1975 1980 1985 1990 1995 2000 2005 2010

120130140150160170180

Water LevelLOESS Trend Line

Well 9131 Site 27 Bryan County

1975 1980 1985 1990 1995 2000 2005 2010

101214161820

468 Water Level

LOESS Trend Line

Well 9840 Washington County Site 28

D EPTH TO WA TER , IN FEET

WATER YEAR

0

Groundwater levels and LOESS trend lines by using available periods of record for wells 25–28. Figure 94.
142 Trends in Base flow, Total Flow, and Base-flow index of Selected Streams in Oklahoma through 2008 1975 1980 1985 1990 1995 2000 2005 2010 10152025

5

Water LevelLOESS Trend Line

Well 9841 Washington County Site 29

1975 1980 1985 1990 1995 2000 2005 2010

10

2468

Water LevelLOESS Trend Line

Well 9602 Nowata County Site 30

1975 1980 1985 1990 1995 2000 2005 2010

1012

2468

Water LevelLOESS Trend Line

Well 9278 Craig County

Site 31

1975 1980 1985 1990 1995 2000 2005 2010

10152025

5 Water Level LOESS Trend Line

Well 9172 Cherokee County Site 32

D EPTH TO WA TER , IN FEET

WATER YEAR

0

0 0

Groundwater levels and LOESS trend lines by using available periods of record for wells 29–32. Figure 95.
Figures

143

1975 1980 1985 1990 1995 2000 2005 2010

1215182124

369

Water LevelLOESS Trend Line

Well 9672 Sequoyah County Site 33

1975 1980 1985 1990 1995 2000 2005 2010

121620

48 Water Level

LOESS Trend Line

Well 9627 Ottawa County

Site 34

1975 1980 1985 1990 1995 2000 2005 2010

303540455055606570

Water LevelLOESS Trend Line

Well 9000 Adair County Site 35

D EPTH TO WA TER , IN FEET

WATER YEAR

0 0

Groundwater levels and LOESS trend lines by using available periods of record for wells 33–35. Figure 96.