Main-Channel Slopes of Selected 

Streams in Iowa for Estimation of 

Flood-Frequency Discharges

By David A. Eash

Iowa City, Iowa

2003

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03–4120

Prepared in cooperation with the

IOWA DEPARTMENT OF TRANSPORTATION and the 

IOWA HIGHWAY RESEARCH BOARD

(Project HR–456)
District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046

For additional information write to:

District Chief

U.S. Geological Survey, WRD

Room 269 Federal Building

P. O. Box 1230

400 South Clinton Street

Iowa City, IA 52244

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does 

not constitute endorsement by the U.S. Geological Survey.

Copies of this report can be purchased 

from:

U.S. Geological Survey

Information Services

Box 25286

Denver Federal Center

Denver, CO 80225
CONTENTS iii

CONTENTS

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

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

Purpose and Scope....................................................................................................................................................... 6

Acknowledgments ....................................................................................................................................................... 6

Main-Channel-Slope Measurement Methods ........................................................................................................................ 6

 Manual Measurements................................................................................................................................................ 7

Geographic Information System Quantifications ........................................................................................................ 8

Comparison of Manual Measurements and Geographic Information System Quantifications .................................. 9

Main-Channel-Slope Curves.................................................................................................................................................. 10

Selection of Streams and Sites..................................................................................................................................... 11

Development of Curves ............................................................................................................................................... 11

Adjustment of Curves .................................................................................................................................................. 15

Presentation of Curves................................................................................................................................................. 17

Estimation of Flood-Frequency Discharges Using Main-Channel-Slope Curves ................................................................. 18

Example 1 .................................................................................................................................................................... 18

Example 2 .................................................................................................................................................................... 19

Summary................................................................................................................................................................................ 20

References Cited.................................................................................................................................................................... 22

Supplemental Data ................................................................................................................................................................ 25

FIGURES

1–3. Maps showing:

1. Location of streams and sites in Iowa used to develop main-channel-slope curves ......................................... 3

2. Des Moines Lobe landform region and hydrologic regions in Iowa................................................................. 5

3. Topographic-map measurements for calculating main-channel slope .............................................................. 8

4. Graph showing examples of curves developed using main-channel-slope values determined from 

manual measurements, GIS quantifications, and adjusted-GIS quantifications ....................................................... 12

5. Graph showing main-channel-slope curves of selected streams in the Raccoon River Basin .................................. 13

6. Map showing main channels of selected streams in the Raccoon River Basin......................................................... 14

7–144. Graphs showing main-channel slopes for:

7. Bear Creek, beginning at mouth in Jackson County ......................................................................................... 47

8. Bear and North Bear Creeks, beginning at mouth of Bear Creek in Allamakee County.................................. 48

9. Beaver Creek, beginning at mouth in Black Hawk County .............................................................................. 49

10. Beaver Creek, beginning at mouth in Polk County........................................................................................... 50

11. Big Bear Creek, beginning at mouth in Iowa County ....................................................................................... 51

12. Big Creek, beginning at mouth in Henry County.............................................................................................. 52

13. Big Creek, beginning at mouth in Linn County ................................................................................................ 53

14. Big Muddy Creek, beginning at mouth in Clay County.................................................................................... 54

15. Black Hawk Creek, beginning at mouth in Black Hawk County...................................................................... 55

16. Boyer River, beginning at mouth in Pottawattamie County.............................................................................. 56

17. Brushy Creek, beginning at mouth in Guthrie County...................................................................................... 58

18. Buffalo and East Branch Buffalo Creeks, beginning at mouth of Buffalo Creek in Jones County................... 59

19. Buttrick Creek, beginning at mouth in Greene County..................................................................................... 60

20. Cedar Creek, beginning at mouth in Henry County.......................................................................................... 61

21. Cedar Creek, beginning at mouth in Mahaska County ..................................................................................... 62

22. Cedar River, beginning at Buchanan-Black Hawk County line ........................................................................ 63

23. Chariton River, beginning at Wayne-Lucas County line................................................................................... 65

24. Chequest Creek, beginning at mouth in Van Buren County.............................................................................. 66

25. Clanton and North Fork Clanton Creeks, beginning at mouth of Clanton Creek in Warren County................ 67

26. Clear Creek, beginning at mouth in Johnson County........................................................................................ 68
iv CONTENTS

27. Crane Creek, beginning at mouth in Black Hawk County................................................................................ 69

28. Crane Creek, beginning at mouth in Fayette County ........................................................................................ 70

29. Crooked and West Fork Crooked Creeks, beginning at mouth of Crooked Creek in Jefferson County........... 71

30. Deep Creek, beginning at mouth in Jackson County ........................................................................................ 72

31. East Boyer River, beginning at mouth in Crawford County ............................................................................. 73

32. East Branch West Nishnabotna River, beginning at mouth in Pottawattamie County...................................... 74

33. East Fork Crooked Creek, beginning at mouth in Washington County ............................................................ 75

34. East Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor County.................. 76

35. East Fork Wapsipinicon River, beginning at mouth in Bremer County............................................................ 77

36. East Nishnabotna River, beginning at mouth in Fremont County..................................................................... 78

37. East Nodaway River, beginning at mouth in Page County ............................................................................... 80

38. English Creek, beginning at mouth in Marion County ..................................................................................... 81

39. English and North English Rivers, beginning at mouth of English River in Washington County.................... 82

40. Farm Creek, beginning at mouth in Mills County ............................................................................................ 84

41. Flint Creek, beginning at mouth in Des Moines County .................................................................................. 85

42. Flood Creek, beginning at mouth in Butler County.......................................................................................... 86

43. Floyd River, beginning at mouth in Woodbury County .................................................................................... 87

44. Fourmile Creek, beginning at mouth in Polk County ....................................................................................... 89

45. Fox River, beginning at Iowa-Missouri State line in Van Buren County.......................................................... 90

46. Grand River, beginning at Iowa-Missouri State line in Ringgold County ........................................................ 91

47. Hardin Creek, beginning at mouth in Greene County....................................................................................... 92

48. Hartgrave Creek, beginning at mouth in Butler County ................................................................................... 93

49. Honey Creek, beginning at mouth in Marshall County .................................................................................... 94

50. Indian Creek, beginning at mouth in Cass County ........................................................................................... 95

51. Indian and East Indian Creeks, beginning at mouth of Indian Creek in Jasper County ................................... 96

52. Iowa River, beginning at Johnson-Iowa County line ........................................................................................ 98

53. Kanaranzi Creek, beginning at mouth in Lyon County..................................................................................... 100

54. Keg Creek, beginning at mouth in Mills County .............................................................................................. 101

55. Little Cedar River, beginning at mouth in Chickasaw County.......................................................................... 103

56. Little Maquoketa River, beginning at mouth in Dubuque County .................................................................... 104

57. Little Rock River, beginning at mouth in Lyon County.................................................................................... 105

58. Little Sioux River, beginning at mouth in Harrison County ............................................................................. 106

59. Little Turkey River, beginning at mouth in Fayette County.............................................................................. 108

60. Little Wapsipinicon River, beginning at mouth in Buchanan County............................................................... 109

61. Little Wapsipinicon River, beginning at mouth in Chickasaw County ............................................................. 110

62. Long and East Long Creeks, beginning at mouth of Long Creek in Decatur County ...................................... 111

63. Long and South Fork Long Creeks, beginning at mouth of Long Creek in Louisa County ............................. 112

64. Lost Island Outlet, Pickerel Run, and Joint drainage ditch 61, beginning at mouth of Lost Island 

Outlet in Clay County ....................................................................................................................................... 113

65. Lytle Creek, beginning at mouth in Jackson County ........................................................................................ 114

66. Maple River, beginning at mouth in Monona County....................................................................................... 115

67. Maquoketa River, beginning at mouth in Jackson County................................................................................ 117

68. Maynes Creek, beginning at mouth in Butler County....................................................................................... 119

69. Middle Nodaway River, beginning at mouth in Montgomery County.............................................................. 120

70. Middle Raccoon River, beginning at mouth in Dallas County ......................................................................... 122

71. Middle River, beginning at mouth in Warren County ....................................................................................... 124

72. Mill Creek, beginning at mouth in Cherokee County ....................................................................................... 126

73. Minerva Creek, beginning at mouth in Marshall County.................................................................................. 127

74. Mosquito Creek, beginning at mouth in Dallas County.................................................................................... 128

75. Mosquito Creek, beginning at mouth in Pottawattamie County ....................................................................... 129

76. Mud Creek, beginning at mouth in Lyon County ............................................................................................. 131

77. Mud Creek, beginning at mouth in Muscatine County ..................................................................................... 132

78. Mud Creek, beginning at mouth in Scott County ............................................................................................. 133

79. Nishnabotna and West Nishnabotna Rivers, beginning at Iowa-Missouri State line in Fremont County......... 134
CONTENTS v

80. Nodaway and West Nodaway Rivers, beginning at Iowa-Missouri State line in Page County ........................ 136

81. North Cedar Creek, beginning at mouth in Marion County ............................................................................. 138

82. North Fork Black Hawk Creek, beginning at mouth in Grundy County .......................................................... 139

83. North Fork Maquoketa River, beginning at mouth in Jackson County ............................................................ 140

84. North River, beginning at mouth in Polk County ............................................................................................. 142

85. North Skunk River, beginning at mouth in Keokuk County............................................................................. 144

86. Ocheyedan River, beginning at mouth in Clay County .................................................................................... 146

87. Old Mans Creek, beginning at mouth in Johnson County................................................................................ 147

88. Otter Creek, beginning at mouth in Buchanan County..................................................................................... 148

89. Otter Creek, beginning at mouth in Lyon County ............................................................................................ 149

90. Otter Creek, beginning at mouth in Warren County ......................................................................................... 150

91. Pigeon Creek, beginning at mouth in Pottawattamie County ........................................................................... 151

92. Platte River, beginning at Iowa-Missouri State line in Taylor County ............................................................. 152

93. Prairie Creek, beginning at mouth in Linn County........................................................................................... 153

94. Raccoon and North Raccoon Rivers, beginning at mouth of Raccoon River in Polk County.......................... 154

95. Roberts Creek, beginning at mouth in Clayton County.................................................................................... 156

96. Rock River, beginning at mouth in Sioux County ............................................................................................ 157

97. Salt Creek, beginning at mouth in Benton County ........................................................................................... 158

98. Sevenmile Creek, beginning at mouth in Montgomery County ....................................................................... 159

99. Shell Rock River, beginning at mouth in Black Hawk County ........................................................................ 160

100. Silver Creek, beginning at mouth in Mills County........................................................................................... 162

101. Sixmile Creek, beginning at mouth in Sioux County ....................................................................................... 163

102. Skunk and South Skunk Rivers, beginning at mouth of Skunk River at Lee-Des Moines County line ........... 164

103. Soap Creek, beginning at mouth in Wapello County........................................................................................ 166

104. Soldier River, beginning at mouth in Harrison County .................................................................................... 167

105. South Beaver Creek, beginning at mouth in Butler County ............................................................................. 168

106. South English River, beginning at mouth in Washington County .................................................................... 169

107. South Fork Chariton River, beginning at Appanoose-Wayne County line ....................................................... 170

108. South Fork Iowa River, beginning at mouth in Hardin County ........................................................................ 171

109. South Raccoon River, beginning at mouth in Dallas County ........................................................................... 172

110. South River, beginning at mouth in Warren County......................................................................................... 174

111. Squaw Creek, beginning at mouth in Story County ......................................................................................... 175

112. Squaw Creek, beginning at mouth in Warren County ...................................................................................... 176

113. Sugar Creek, beginning at mouth in Muscatine County................................................................................... 177

114. Sugar Creek, tributary to the Des Moines River, beginning at mouth in Lee County ...................................... 178

115. Sugar Creek, tributary to the Mississippi River, beginning at mouth in Lee County ....................................... 179

116. Tarkio River, beginning at Iowa-Missouri State line in Page County............................................................... 180

117. Thompson River, beginning at Iowa-Missouri State line in Decatur County................................................... 181

118. Timber and South Timber Creeks, beginning at mouth of Timber Creek in Marshall County ........................ 183

119. Troublesome Creek, beginning at mouth in Cass County ................................................................................ 184

120. Turkey Creek, beginning at mouth in Cass County .......................................................................................... 185

121. Turkey River, beginning at mouth in Clayton County...................................................................................... 186

122. Upper Iowa River, beginning at mouth in Allamakee County.......................................................................... 188

123. Volga River, beginning at mouth in Clayton County ........................................................................................ 190

124. Walnut Creek, beginning at mouth in Fremont County.................................................................................... 191

125. Walnut and Middle Walnut Creeks, beginning at mouth of Walnut Creek in Jefferson County ...................... 192

126. Wapsinonoc and West Branch Wapsinonoc Creeks, beginning at mouth of Wapsinonoc Creek in 

Muscatine County ............................................................................................................................................. 193

127. Wapsipinicon River, beginning at mouth at Scott-Clinton County line............................................................ 194

128. Waterman Creek, beginning at mouth in O’Brien County ............................................................................... 197

129. Weldon River, beginning at Iowa-Missouri State line in Decatur County........................................................ 198

130. West Branch Floyd River, beginning at mouth in Plymouth County................................................................ 199

131. West Branch One Hundred and Two River, beginning at mouth in Taylor County.......................................... 200

132. West Fork Cedar River, beginning at mouth in Black Hawk County ............................................................... 201
vi CONTENTS

133. West Fork Ditch and West Fork Little Sioux River, beginning at Monona-Woodbury County line................. 202

134. West Fork Middle Nodaway River, beginning at mouth in Adair County........................................................ 204

135. West Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor County................. 205

136. West Fork West Nishnabotna River, beginning at mouth in Shelby County..................................................... 206

137. White Breast Creek, beginning at mouth in Marion County ............................................................................ 207

138. Whitewater Creek, beginning at mouth in Jones County.................................................................................. 209

139. Willow Creek, beginning at mouth in Guthrie County ..................................................................................... 210

140. Willow Creek, beginning at mouth in Harrison County.................................................................................... 211

141. Willow Creek, beginning at mouth in Plymouth County.................................................................................. 212

142. Winnebago River, beginning at mouth in Floyd County................................................................................... 213

143. Wolf Creek, beginning at mouth in Black Hawk County.................................................................................. 214

144. Yellow River, beginning at mouth in Allamakee County.................................................................................. 215

TABLES

1. Flood-frequency estimation equations for Region 1............................................................................................... 4

2. Flood-frequency estimation equations for Region 2............................................................................................... 4

3. Flood-frequency estimation equations for Region 3............................................................................................... 4

4. Statistical summary of percentage differences between flood-frequency discharge estimates for 

selected streamflow-gaging stations in Regions 2 and 3 calculated using manual measurements and 

GIS quantifications of main-channel slope ............................................................................................................. 15

5. Statistical summary of percentage differences between flood-frequency discharge estimates for selected 

streamflow-gaging stations in Regions 2 and 3 calculated using manual measurements and adjusted-GIS 

quantifications of main-channel slope..................................................................................................................... 16

6. Comparison of manual measurements and GIS quantifications of main-channel slope for selected 

streamflow-gaging stations in Region 2.................................................................................................................. 27

7. Comparison of manual measurements and GIS quantifications of main-channel slope for selected 

streamflow-gaging stations in Region 3.................................................................................................................. 31

8. Comparison of manual measurements and GIS quantifications of main-channel slope using 1:24,000-scale 

topographic data for selected streamflow-gaging stations in Iowa ......................................................................... 32

9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa 

using a geographic information system technique and 1:24,000-scale topographic data and used to develop 

unadjusted main-channel-slope curves for figures 7–144....................................................................................... 33

CONVERSION FACTORS, ABBREVIATIONS, AND VERTICAL DATUM

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD29).

Multiply By To obtain

inch 25.4 millimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

square mile (mi2) 2.590 square kilometer 

foot per mile (ft/mi) 0.1894 meter per kilometer

cubic foot per second (ft3/s) 0.02832 cubic meter per second 
Abstract 1

Main-Channel Slopes of Selected Streams in Iowa 

for Estimation of Flood-Frequency Discharges

By David A. Eash

Abstract

This report describes a statewide study 

conducted to develop main-channel slope (MCS) 

curves for 138 selected streams in Iowa with 

drainage areas greater than 100 square miles. 

MCS values determined from the curves can be 

used in regression equations for estimating floodfrequency discharges. Multivariable regression 

equations previously developed for two of the 

three hydrologic regions defined for Iowa require 

the measurement of MCS. Main-channel slope is 

a difficult measurement to obtain for large streams 

using 1:24,000-scale topographic maps. The 

curves developed in this report provide a simplified method for determining MCS values for sites 

located along large streams in Iowa within hydrologic Regions 2 and 3. 

The curves were developed using MCS 

values quantified for 2,058 selected sites along 

138 selected streams in Iowa. A geographic

information system (GIS) technique and 

1:24,000-scale topographic data were used to 

quantify MCS values for the stream sites. The 

sites were selected at about 5-mile intervals along 

the streams. River miles were quantified for each 

stream site using a GIS program. Data points for 

river-mile and MCS values were plotted and a 

best-fit curve was developed for each stream. 

An adjustment was applied to all 138 

curves to compensate for differences in MCS 

values between manual measurements and GIS 

quantifications. The multivariable equations for 

Regions 2 and 3 were developed using manual 

measurements of MCS. A comparison of manual 

measurements and GIS quantifications of MCS 

indicates that manual measurements typically 

produce greater values of MCS compared to GIS 

quantifications. Median differences between 

manual measurements and GIS quantifications of 

MCS are 14.8 and 17.7 percent for Regions 2 and 

3, respectively. Comparisons of percentage differences between flood-frequency discharges calculated using MCS values of manual measurements 

and GIS quantifications indicate that use of GIS 

values of MCS for Region 3 substantially underestimate flood discharges. Mean and median 

percentage differences for 2- to 500-year recurrence-interval flood discharges ranged from 

5.0 to 5.3 and 4.3 to 4.5 percent, respectively, for 

Region 2 and ranged from 18.3 to 27.1 and 

12.3 to 17.3 percent for Region 3.

The MCS curves developed from GIS 

quantifications were adjusted by 14.8 percent for 

streams located in Region 2 and by 17.7 percent 

for streams located in Region 3. Comparisons of 

percentage differences between flood discharges 

calculated using MCS values of manual measurements and adjusted-GIS quantifications for 

Regions 2 and 3 indicate that the flood-discharge 

estimates are comparable. For Region 2, mean 

percentage differences for 2- to 500-year recurrence-interval flood discharges ranged between 

0.6 and 0.8 percent and median differences were 

0.0 percent. For Region 3, mean and median 

differences ranged between 5.4 to 8.4 and 0.0 to 

0.3 percent, respectively.

A list of selected stream sites presented 

with each curve provides information about the 

sites including river miles, drainage areas, the 

location of U.S. Geological Survey streamflowgaging stations, and the location of streams 
2 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

crossing hydrologic region boundaries or the Des 

Moines Lobe landform region boundary. Two 

examples are presented for determining river-mile 

and MCS values, and two techniques are 

presented for computing flood-frequency 

discharges.

 INTRODUCTION

Reliable estimates of flood-frequency 

discharges are essential for the economical planning 

and safe design of bridges, dams, levees, and other 

structures located along rivers and streams and for the 

effective management of flood plains. Techniques that 

are as accurate as possible, while being relatively easy 

to apply, are needed to estimate flood-frequency 

discharges at ungaged stream sites in Iowa. Regression 

analyses performed on data collected at streamflowgaging stations are used to develop equations to estimate flood-frequency discharges at ungaged sites. The 

equations are developed by relating flood-frequency 

discharges to significant basin characteristics for 

selected gaging stations. 

Regression equations for estimating floodfrequency discharges for streams in Iowa were previously developed for three hydrologic regions defined 

for the State (Eash, 2001). Figure 1 shows the three 

hydrologic regions. In Eash (2001), one-variable equations that include drainage area (DA) as the explanatory variable were developed for each of the three 

regions. Three-variable equations were developed for 

Region 2 that include DA, main-channel slope (MCS), 

and the ratio of basin area within the Des Moines Lobe 

landform region to total area of the basin (DML); twovariable equations were developed for Region 3 that 

include DA and MCS. Two sets of flood-frequency 

estimation equations were published for Regions 2 and 

3 because one-variable equations are considered easy 

for users to apply and the predictive accuracies of 

multivariable equations are greater. Standard error of 

prediction for the one-variable equations ranges from 

about 34 to 45 percent and for the multivariable equations from about 31 to 42 percent. 

Tables 1–3 list the equations with the greatest 

predictive accuracies for each of the three hydrologic 

regions in Iowa (Eash, 2001). Depending on which 

region a stream site is located within, these equations 

require the measurement of one to three basin characteristics for the estimation of flood-frequency 

discharges. Measurements of DA can be determined 

for many stream sites directly or interpolated indirectly from Larimer (1957). Drainage area also can be 

determined by planimetering or digitizing basin 

boundaries from topographic maps. Figure 2 shows 

the location of the Des Moines Lobe landform region. 

Measurements of DML can be obtained for stream 

sites located within Region 2 by delineating the basin 

boundary for the stream site in figure 2 and determining the ratio of basin area within the Des Moines 

Lobe landform region (shaded area shown in figure 2) 

to total area of the basin. 

The USGS has compiled all of the current (as of 

2002) regression equations for estimating floodfrequency discharges for rural, unregulated watersheds 

in all the States, the Commonwealth of Puerto Rico, 

and the island of Tutuilla, America Samoa (from 

52 flood-frequency estimation reports) into a computer 

program titled the National Flood Frequency (NFF) 

Program (Ries and Crouse, 2002). The two most prevalent watershed/climatic characteristics included in the 

regression equations in the NFF program were DA and 

MCS. Drainage area was included in all 52 floodfrequency reports and MCS was included in 27 of the 

reports. Main-channel slope is a significant characteristic in the estimation of flood-frequency discharges 

nationwide, and in particular in the upper Midwest, 

where MCS is a significant characteristic in the estimation of flood discharges in Iowa and all adjacent 

States (Alexander and Wilson, 1995; Eash, 2001; Krug 

and others, 1992; Lorenz and others, 1997; Sando, 

1998; Soenksen and others, 1999; and David Soong, 

U.S. Geological Survey, Illinois District, written 

commun., December 2002). 

Measurements of MCS can be made for stream 

sites in Iowa located within Regions 2 or 3 by 

following the technique for manual, topographic-map 

measurements presented in the “Manual Measurements” section of this report. Measurements of MCS 

are determined using 1:24,000-scale topographic data 

(Office of Water Data Coordination, 1978) because 

this scale provides more accurate measurements of 

MCS than smaller scale data, such as 1:100,000 or 

1:250,000. MCS is a difficult manual measurement to 

obtain for large streams using 1:24,000-scale topographic maps. A simplified method for determining 

MCS values for sites located on large streams is 

needed to facilitate the application of the multivariable 

equations. 
INTRODUCTION 3

! !

! !

SOUTH

MINNESOTA

MISSOURI

W

DAKOTA

NEBRASKA

Pocahontas

Kossuth Lyon Osceola Dickinson Emmet Winnebago Worth Mitchell

Humboldt

Palo Alto

Calhoun

Webster

Wright

Howard Winneshiek Allamakee

Sioux O'Brien Clay Hancock Cerro Gordo Floyd Chickasaw

Fayette Clayton

Plymouth Cherokee Buena Vista Franklin Butler Bremer

Woodbury Black Hawk Buchanan Delaware Dub

Hamilton Hardin Grundy Ida Sac

Monona Crawford Carroll Greene Boone Story Marshall

Tama Benton Linn Jones 

Harrison Shelby Audubon Guthrie Dallas Polk Jasper Poweshiek Iowa Johnson

Cedar

Pottawattamie Cass Adair Madison Warren Marion Mahaska Keokuk Washington

Muscatine

Mills Montgomery Adams Union Clarke Lucas Monroe Wapello Jefferson Henry

Louisa

Fremont Page Taylor Ringgold Decatur Wayne Appanoose Davis Van Buren

Lee

Des Moine

1

2

3

Boyer

Keg

Silver

Soldier

Platte

River

Willow

Winnebago River

River

North English

Clear

Turkey Creek

Minerva Creek

Indian

Sugar Creek

Fork Iowa River

Big Creek

Creek

Bear 

Sugar

Creek

Mud Creek

Bear

 Creek North

 Bear

Creek

Black

Hawk

Beaver Creek

South

Beaver

Beaver

Creek

Big Bear

Creek

Big

Creek

River

Brushy

Creek

East Branch

Buffalo

Buttrick

Creek

Creek

Cedar

Creek

North

Cedar

Creek

Cedar

Cedar

River

Cedar

River

Little Cedar

River

Upper

Iowa

River

Yellow

Roberts Creek

Turkey

River

Turkey River

Volga

River

Little

Turkey

River

Crane

Creek

Crane Creek

River

Wapsipinicon

Maquoketa

L

North Fork

Otter

Creek

M

Sugar

Prairie

Creek

Flood

Creek

West Fork Cedar River

Hartgrave

Creek

Maynes Creek

River

Rock

Shell

Wolf

Creek

Timber South

 Creek

 Timber

Honey

Creek

Iowa

River

Salt

Iowa

River

Wapsinonoc

 Creek

West

 Branch

River

English

River

South English River

Creek

Creek

Flint

Skunk River

Long

South Fork

West Fork

Creek

Crooked

North

River

Skunk

Walnut

 Creek

Middle

 Walnut

Skunk

River

River

South

Skunk

East IndianCreek

Wapsipinicon River Little

East Fork Wapsip ni ci on River

Little

Wapsipinicon River

North Fork

South

East

Fork

Creek

Soap

Creek

Chequest Creek

Fox

River

South Fork Chariton River

Chariton

River

English

Creek

Creek

White

Breast Weldon River

North

River

Middle

River

ClantonCreek North Fork

Otter Creek

Squaw

Creek

South

River

Fourmile

Creek

Raccoon

River

Long

 Creek

East Long

 Creek

Thompson

River

River

Grand River

EastFork One Hundr ed

and Two River

West Fork One Hundred and

TwoRiver

West Branch

East Nodaway

River

Nodaway

Middle

River

West Fork

Se v enmile Cr eek

West Nodaway

River

Nodaway

 River

Tarkio

South

Raccoon

River

Nishnabotna

River

Creek West

Nishnabotna

River

Walnut Creek

Farm Creek

Creek

Indian

East

Nishnabotna

River

TroublesomeCreek

Creek

Mosquito

Creek

Pigeon

Creek

Willow Creek

Mosquito Creek

Middle

Raccoon River

Creek

East

Boyer

River

Maple

River

Little

Sioux

River

West Fork

 Ditch

West ForkLittle Sioux River

Raccoon

River

North

Hardin Creek

Otter

Creek

Little

Rock

River

Rock

River

Kanaranzi

 Creek

Sixmile C reek

Floyd

River

West Branch Floyd River

Willow

Mill

Creek

Waterman Creek

Ocheyedan River

Little Sioux

River Big Muddy Creek Lost

 IslandPickerel

 Run D.D.

 61

East

Branch

Old

Mans

Creek

Creek

West Fork

Squaw

Creek

Creek

41°

42°

9

95° 94° 93° 92° 96°

43°

Creek

0 20 40 60 MILES

EXPLANATION 0 20 40 60 KILOMETERS

Site used for GIS quantification of main-channel slope

2 Hydrologic region boundary and number Stream included in main-channel-slope study

Base from U.S. Geological Survey digital data,1:24,000,Universal Transverse Mercator projection,Zone 15, horizontal datum North American Datum of 1927

Figure 1. Location of streams and sites in Iowa used to develop main-channel-slope curves.
4 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

Table 1. Flood-frequency estimation equations for Region 1

[Data from Eash (2001, table 3). SEE, standard error of estimate; SEP, average standard error of prediction; EYR, equivalent years of record; Q, peak 

discharge, in cubic feet per second for recurrence interval, in years, indicated as subscript; DA, drainage area, in square miles]

Estimation equation SEE

(percent)

SEP

(percent)

EYR

(years)

(One-variable equations; number of streamflow-gaging stations = 26)

Q2 = 33.8 DA.656 35.3 41.4 4.2

Q5 = 60.8 DA.658 32.0 39.4 5.8

Q10 = 80.1 DA.660 31.1 39.0 7.7

Q25 = 105 DA.663 31.3 39.2 10.1

Q50 = 123 DA.666 32.0 39.8 11.5

Q100 = 141 DA.669 33.1 40.5 12.5

Q200 = 159 DA.672 34.5 41.4 13.2

Q500 = 183 DA.676 36.5 42.7 13.7

Table 2. Flood-frequency estimation equations for Region 2

[Data from Eash (2001, table 4). SEE, standard error of estimate; SEP, average standard error of prediction; EYR, equivalent years of record; Q, peak 

discharge, in cubic feet per second for recurrence interval, in years, indicated as subscript; DA, drainage area, in square miles; MCS, main-channel 

slope, in feet per mile; DML, Des Moines Lobe, ratio of basin area within Des Moines Lobe landform region to total area of basin]

Estimation equation SEE

(percent)

SEP

(percent)

EYR

(years)

(Three-variable equations; number of streamflow-gaging stations = 188)

Q2 = 52.2 DA.677 MCS.316 (DML+1)–.753 37.3 41.7 4.6

Q5 = 144 DA.616 MCS.305 (DML+1)–.653 25.4 34.5 11.3

Q10 = 225 DA.590 MCS.306 (DML+1)–.601 21.6 32.0 19.9

Q25 = 337 DA.567 MCS.309 (DML+1)–.567 20.4 31.3 29.5

Q50 = 430 DA.554 MCS.311 (DML+1)–.555 21.2 31.9 33.2

Q100 = 531 DA.542 MCS.313 (DML+1)–.549 22.6 32.9 34.3

Q200 = 641 DA.532 MCS.316 (DML+1)–.545 24.6 34.4 33.7

Q500 = 800 DA.519 MCS.320 (DML+1)–.542 27.8 36.5 31.7

Table 3. Flood-frequency estimation equations for Region 3

[Data from Eash (2001, table 5). SEE, standard error of estimate; SEP, average standard error of prediction; EYR, equivalent years of record; Q, peak 

discharge, in cubic feet per second for recurrence interval, in years, indicated as subscript; DA, drainage area, in square miles; MCS, main-channel 

slope, in feet per mile]

Estimation equation SEE

(percent)

SEP

(percent)

EYR

(years)

(Two-variable equations; number of streamflow-gaging stations = 27)

Q2 = 7.75 DA.888 MCS.977 29.4 38.0 5.2

Q5 = 22.6 DA.805 MCS.939 22.2 33.3 11.5

Q10 = 40.0 DA.761 MCS.910 19.6 31.6 18.9

Q25 = 72.3 DA.715 MCS.875 18.0 30.8 29.2

Q50 = 108 DA.683 MCS.845 17.8 30.9 35.2

Q100 = 158 DA.652 MCS.809 18.6 31.6 38.5

Q200 = 232 DA.621 MCS.769 19.9 32.8 39.2

Q500 = 382 DA.580 MCS.709 22.4 34.8 37.4
INTRODUCTION 5

Pocahontas

Kossuth Lyon

Rock

Pipestone

Lincoln

Nobles

Murray

Lyon

Jackson

Cottonwood

Redwood

Martin Faribault Freeborn Mower Fillmore

Osceola Dickinson Emmet Winnebago Worth Mitchell

Humboldt

Palo Alto

Calhoun

Webster

Wright

Howard

Sioux O'Brien Clay Hancock Cerro Gordo Floyd Chickasaw

Plymouth Cherokee Buena Vista Franklin Butler Bremer

Woodbury

Black Hawk

Hamilton Hardin Grundy Ida Sac

Monona Crawford Carroll Greene Boone Story Marshall

Tama Benton

Harrison Shelby Audubon Guthrie Dallas Polk Jasper Poweshiek Iowa

Pottawattamie Cass Adair Madison Warren Marion Mahaska Keokuk

Mills Montgomery Adams Union Clarke Lucas Monroe Wapello Jefferson

96° 95°

94° 93° 92°

43°

44°

42°

EXPLANATION

Des Moines Lobe landform region

Des Moines Lobe landform region boundary within Iowa (Tim Kemmis, Iowa 

Geological Survey Bureau, written commun., November 1998) 

Des Moines Lobe landform region boundary within Minnesota [western boundary

modified from MLRA-103 Stratigraphic/Geomorphic Field Investigation map (1995)

provided by Deb Quade, Iowa Geological Survey Bureau, written commun.,

November 1998; eastern boundary modified from Soller and Packard (1998)]

Hydrologic region boundary and number 

0 40 20 60 80 MILES

0 40 20 60 80 KILOMETERS

41°

NEBRASKA

Rock

River

Floyd

River

Little

R

Maple

River

Soldier

R

Boyer

River

West

Nishnabotna

River

East

Nishnabotna

River

Middle

North

South

Middle Nodaway River

Thompson

Silver

Creek

Mosquito

Creek

Little Rock River

West

Branch

Sioux

Little

Fork West

Creek

River

Mill

Sioux

Sioux

River

3

River

Raccoon R

Moines

River

River

North

Skunk

River

River

River

Cedar

Cedar Cr

Creek

Breast

White

South

River

Creek

Iowa

Wapsipinicon

River

Cedar

River

Shell

Rock

River

West

Fork

Cedar

River

Cedar

River

Upper Iowa

Turkey

River

River

Little

Cedar

Cr

Wolf

Creek

MINNESOTA

1

2

Winnebago

Iowa

River

East

Fork

Des

Des

Moines

Boone

River

North

Raccoon

River

Middle

Raccoon

South

Skunk

Des

Moines

River

River

River

South

Fork

Beaver

Creek

Creek

Indian

Little

2

River

Black

River

River

H awk

Ocheyedan

Raccoon

Base from U.S. Geological Survey digital data,

1:2,000,000, 1979

Universal Transverse Mercator projection,

Zone 15, horizontal datum

North American Datum of 1927

Figure 2. Des Moines Lobe landform region and hydrologic regions in Iowa (from Eash, 2001, figure 12).
6 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

In response to the need to provide users with a 

simplified method for determining MCS values for 

sites located along large streams in Iowa within 

Regions 2 and 3, the U.S. Geological Survey (USGS), 

in cooperation with the Iowa Department of Transportation and the Iowa Highway Research Board, initiated 

a statewide study in 2001 to develop curves for determining MCS values for sites along large, unregulated 

streams in Iowa within Regions 2 and 3.

Purpose and Scope

The purposes of this report are to: (1) present 

the results of geographic information system (GIS) 

techniques using 1:24,000-scale digital topographic 

data to quantify MCS at selected sites along large, 

unregulated streams in Iowa with drainage areas 

greater than 100 mi2 that are located in hydrologic 

Regions 2 and 3; (2) present best-fit curves developed 

for selected streams showing relations between GIS 

quantifications of MCS and river miles, and river-mile 

information for selected stream sites; and (3) present 

comparisons of manual measurements of MCS used to 

develop regression equations and GIS quantifications 

of MCS to determine whether adjustment factors are 

needed for applying the GIS quantifications of MCS to 

the regression equations. This report provides users 

with a simplified method for determining MCS values 

for sites located along large streams in Iowa within 

Regions 2 and 3. If a stream site within Region 2 or 3 

is not located along one of the streams selected for 

inclusion in this report or is located upstream from one 

of the MCS curves developed in this report, a manual 

measurement of MCS using 1:24,000-scale topographic data will be needed (see the five measurement 

steps listed in the section “Manual Measurements”).

Acknowledgments

The author gratefully acknowledges Todd Noah, 

Assistant GIS Coordinator, Iowa Department of Transportation, for providing a GIS data layer of roads in 

Iowa used for determining “911” street names; and the 

following USGS personnel: Ed Fischer, for his work to 

develop computer programs to compile and format 

data for the main-channel slope graphs and lists of 

sites; Mark Delperdang, for his work to digitize 

1:24,000-scale main channels, quantify MCS values 

for stream sites using GIS software, compile data for 

the MCS graphs and lists, and prepare maps for this 

report; Gina Renzi, for her work to digitize 1:24,000-

scale main channels, compile data for the tables, MCS 

graphs and lists, and prepare tables for this report; 

Andy Fish and Brian Lanning, for their work to digitize 1:24,000-scale main channels and quantify MCS 

values for stream sites using GIS software; Dan Christiansen, for his work to digitize 1:24,000-scale main 

channels and compile data for the tables; and Kymm 

Barnes, for her work to develop a GIS program to 

select main channels and determine river miles for 

each selected stream site. 

MAIN-CHANNEL-SLOPE MEASUREMENT 

METHODS

 Two different methods have been used to 

measure MCS for streamflow-gaging stations in Iowa. 

Manual measurements using topographic maps have 

traditionally been used to measure MCS. These 

measurements can be tedious and time-consuming to 

obtain, especially for larger streams, and different 

methods have been used over the years to measure 

main-channel length (MCL). Improvements in 

computer technology and the availability of digital 

topographic data in the last decade have enabled the 

use of GIS technology to automate the quantification 

of MCS. A geographic information system provides an 

efficient and consistent method of quantifying MCS. 

Information in this section describes both manual 

measurements and GIS quantifications and compares 

MCS values determined using the methods.

The equation for calculating main-channel slope 

(MCS) is:

MCS = (E85 – E10) / (0.75 MCL), (1)

where

MCS = an index of the slope, in feet per mile, of the 

main channel;

E85 = the streambed elevation, in feet, at 85 percent 

of the main-channel length upstream from 

the stream site;

E10 = the streambed elevation, in feet, at 10 percent 

of the main-channel length upstream from 

the stream site;
MAIN-CHANNEL-SLOPE MEASUREMENT METHODS 7

MCL = main-channel length, in miles, measured 

along the main channel from the stream 

site to where the main-channel extension 

meets the basin divide.

 Manual Measurements

Main-channel slope measurements were identified as significant basin characteristics in the development of flood-frequency estimation equations by 

Benson (1959, 1962). In his 1959 paper, Benson correlated different measurements of channel slope to 

flood-frequency-discharge data for streamflow-gaging 

stations in New England. Benson determined that the 

slope between 10 and 85 percent of the total length of 

the main channel provided the best correlation with the 

flood-frequency discharges.

Manual measurements of MCS for 178 streamflow-gaging stations in Iowa began in the early 1960’s 

by Schwob (1966). Early measurements of MCS were 

determined by a combination of methods. For large 

streams, 0.25-mi chords on 1:250,000-scale topographic maps were used to measure MCL. Schwob 

(1966) noted that for small streams, larger scale topographic maps (1:24,000 or 1:62,500) or soil maps were 

used, and that streambed elevations for calculating 

MCS were determined from topographic maps whenever possible. For streams with drainage areas less 

than 100 mi2, elevations were obtained by rough 

leveling if large-scale topographic maps were not 

available. Schwob (1966) presented MCS curves for 

27 large rivers in Iowa (rivers with drainage areas 

greater than 700 mi2

). 

Manual measurements of MCL from 1:24,000-

scale topographic maps were initially determined for 

streamflow-gaging stations in Iowa using dividers 

graduated at 0.1-mi units (Burmeister, 1970). Dividermethod measurements of MCL are listed in table 6 (in 

the “Supplemental Data” section) under the map-scale 

column as “24k.” Beginning in the late 1980’s, graph 

paper overlain on 1:24,000-scale topographic maps on 

a light table was used to measure MCL by aligning the 

ruling on the graph paper along the main channel. The 

graph-paper method produces a greater value for MCL 

compared to the divider method because the majority 

of the sinuosity of the channel is included in the graphpaper-method measurement. Graph-paper-method 

measurements of MCL are listed in tables 6 and 7 

under the map-scale column as “24kg.” As part of the 

most recent flood-frequency estimation study (Eash, 

2001), manual measurements of MCS (using the 

graph-paper method) were obtained for gaging stations 

that had not previously been measured. The MCS data 

set used to develop the multivariable regression equations for Regions 2 and 3 (tables 2 and 3) included 

manual measurements of MCS that were determined 

during the early 1960’s to 1998.

Figure 3 illustrates the technique for manual, 

topographic-map measurement of MCS for the Rapid 

Creek tributary near Iowa City streamflow-gaging 

station (station number 05453950). The manual 

measurement of MCS involves five steps:

1. Using 1:24,000-scale topographic maps, identify 

the location of the stream site for which the 

flood-frequency estimate is to be made. Determine the main channel of the stream network 

from the stream site upstream to the basin divide. 

At each stream fork, follow the fork that contributes the greater drainage area. At the upstream 

end, extend the main channel of the stream to the 

basin divide. Figure 3 shows the main channel 

and the main-channel extension highlighted for 

the example basin. 

2. Measure the total length of the main channel, in 

miles, from stream site to basin divide. Figure 3 

shows that the MCL for the example basin is 

4.0 mi. 

3. Locate two points on the main channel, one that is 

10 percent of the total length of the main channel 

(0.10 MCL) upstream from the stream site, and 

the other that is 85 percent of the total length 

(0.85 MCL), or 15 percent of the total length 

downstream from where the main channel meets 

the basin divide. Figure 3 shows the location of 

the 0.10-MCL and 0.85-MCL points on the main 

channel. 

4. For both of the 0.10- and 0.85-MCL points, locate 

the nearest elevation-contour lines on the topographic 

map that cross the main channel upstream and downstream from each point.Usingthe elevations determined for these contour lines, interpolate an elevation 

for each of the 0.10-MCL and 0.85-MCL points. 

Figure 3 shows that the 700-ft and 690-ft contours are 

the nearest contour lines crossing the main channel 

upstream and downstream from the 0.10 MCL point, 

and an elevation (E10) of 696 ft was interpolated for 

the 0.10 MCL point. Likewise, 790-ft and 780-ft 
8 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

contours are the nearest contour lines upstream and 

downstream from the 0.85 MCL point, and an elevation (E85) of 786 ft was interpolated for the 0.85 MCL 

point.

5. For the example basin shown in figure 3, the manual 

measurement of MCS from 1:24,000-scale topographic maps is calculated using equation 1:

MCS = (E85 – E10) / (0.75 MCL)

MCS = (786 – 696) / (0.75 × 4.0)

MCS = 90/3.0 = 30.0 ft/mi

Geographic Information System 

Quantifications

 Geographic information system quantifications 

of MCS for 164 streamflow-gaging stations in Iowa 

began in the early 1990’s (Eash, 1993) with the use of 

Basinsoft, a computer program developed by the 

USGS to quantify selected drainage-basin characteristics (Majure and Soenksen, 1991; Eash, 1994). Early 

GIS quantifications of MCS were determined using 

two scales of digital data. Main-channel length quantifications were determined using 1:100,000-scale 

digital line graph (DLG) hydrography or streamnetwork data and elevations E10 and E85 were determined using hypsography or elevation-contour data 

created from 1:250,000-scale digital elevation model 

(DEM) data. 

Following the redevelopment of Basinsoft in 

1994 (Harvey and Eash, 1996), elevations E10 and E85 

Main-channel extension

to basin divide 

Main channel of basin

main-channel length

(MCL) = 4.0 miles

Main-channel slope (MCS) calculation

MCS = (E - E ) / (0.75 MCL) 85 10

790-foot

elevation

contour

780-foot

elevation

contour

690-foot

elevation

contour

700-foot

elevation

contour

Stream site (station number 05453950)

Stream

Elevation contour, NGVD of 1929

Drainage divide

EXPLANATION

Base from U.S. Geological Survey digital data,

1:24,000, 1993

Universal Transverse Mercator projection

Zone 15, horizontal datum

North American Datum of 1927

0 0.2 0.4 0.6 MILE

0 0.2 0.4 0.6 KILOMETER

41°40'45"

41°42'15"

91°26'

91°28'45"

0.10 MCL

E = 696 feet 10

0.85 MCL

E = 786 feet 85

Figure 3. Topographic-map measurements for calculating main-channel slope (from Eash, 2001, figure 17).
MAIN-CHANNEL-SLOPE MEASUREMENT METHODS 9

were determined using DEM (raster) data instead of 

hypsography (vector) data. As part of the 2001 floodfrequency estimation study (Eash, 2001), GIS quantifications of MCS were determined for 291 streamflowgaging stations in Iowa and adjacent States by using 

Basinsoft. The MCL values were quantified using 

1:100,000-scale DLG hydrography data. Elevations 

E10 and E85 were quantified using DEM data created 

from 1:100,000-scale DLG hypsography and hydrography data.

For this report, GIS quantifications of MCS 

were determined using Basinsoft for 2,058 selected 

stream sites in Iowa (fig. 1). These sites include 

126 continuous-record and high-flow, partial-record 

(crest-stage) streamflow-gaging stations (tables 6–7 in 

the “Supplemental Data” section). MCL values were 

quantified using main channels digitized from 

1:24,000-scale digital raster graphic (DRG) data. 

Elevations E10 and E85 were determined using 30-

meter (1:24,000-scale) DEM data. In this report, GIS 

quantifications of MCS were determined using a larger 

scale of data (1:24,000) than was used in previous 

studies (1:250,000 and 1:100,000; Eash, 1993, 2001).

A GIS quantification of MCS using Basinsoft 

requires the generation of four source-data layers—

three coverages representing the drainage-divide, 

hydrography, and hypsography, and one lattice-elevation model of a drainage basin. The blue lines shown 

in figure 3 compose the hydrography data layer for the 

basin, the brown lines compose the hypsography data 

layer, and the black dashed line composes the 

drainage-divide data layer. Not shown in figure 3 is the 

lattice-elevation-model data layer, which is a grid of 

elevations generated from 30-meter DEM data. 

A Basinsoft quantification of MCS involves four 

user-interactive steps. Each step launches an automated process:

1. The arc segments of the hydrography data layer 

(blue lines in fig. 3) are oriented in a downstream 

direction by selecting the location of the stream 

site within the stream network (black triangle in 

fig. 3).

2. The main channel is extended to the basin divide by 

digitizing an arc from the basin divide to the 

upstream end of the main channel. This mainchannel extension arc is shown as a dashed blue 

line in figure 3.

3. All arc segments representing the main channel are 

assigned a code within the hydrography data 

layer by selecting the upstream and downstream 

ends of the main channel. The arc segments 

coded as main-channel segments by Basinsoft are 

highlighted in figure 3.

4. A route system is developed based on the arc 

segments coded as the main channel by initiating 

the main Basinsoft program. The lengths of these 

arc segments are added to quantify MCL. The 10 

and 85 percent distances from the downstream 

end of the main channel are computed and nodes 

are placed at those positions along the route (red 

dots in fig. 3). The nodes are converted to points 

and elevations (E10 and E85) are quantified for 

each point from the lattice-elevation-model data 

layer.

For the example basin shown in figure 3, the 

GIS quantification of MCS from 1:24,000-scale digital 

topographic data is calculated using equation 1:

MCS = (E85 – E10) / (0.75 MCL)

MCS = (778.4 – 692.5) / (0.75 × 4.20)

MCS = 85.9/3.15 = 27.3 ft/mi

Comparison of Manual Measurements and 

Geographic Information System 

Quantifications

Manual measurements of MCS have been investigated for use in regression analyses for four floodfrequency estimation studies conducted for Iowa by 

Schwob (1966), Lara (1973, 1987), and Eash (2001). 

GIS quantifications of MCS have been investigated for 

use in two studies conducted for Iowa by Eash (1993, 

2001). In the 2001 study, both manual measurements 

and GIS quantifications (1:100,000 scale) of MCS 

were investigated for use in regression analyses; the 

manual measurements of MCS were better correlated 

with flood-frequency discharges and they were used to 

develop the regression equations for Regions 2 and 3 

(tables 2 and 3). 

Tables 6 and 7 (in the “Supplemental Data” 

section at the end of the report) compare manual 

measurements and GIS quantifications of MCS, MCL, 

and E85–E10 for selected streamflow-gaging stations 

in Regions 2 and 3, respectively. GIS quantifications 

of MCS listed in tables 6 and 7 were determined as 

part of this report. The MCS values listed in table 6 
10 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

were compiled for 99 gaging stations in Iowa of the 

188 total gaging stations used to develop the regression equations for Region 2 (table 2). Table 7 lists 

MCS values for all 27 gaging stations used to develop 

the regression equations for Region 3 (table 3). 

Tables 6 and 7 indicate that manual measurements typically produce greater values of MCS 

compared to GIS quantifications. Percentage differences between manual measurements and GIS quantifications of MCS, MCL, and E85–E10 are listed in 

tables 6 and 7. Summary statistics for the mean, 

median, minimum, and maximum percentage differences are listed at the end of each table. Mean 

percentage differences between manual measurements and GIS quantifications of MCS are 19.7 and 

27.9 percent (tables 6 and 7, respectively), and median 

differences are 14.8 and 17.7 percent. A comparison of 

mean and median differences for MCL and E85–E10

indicate that differences in the values of MCL explain 

the majority of the differences between manual and 

GIS values of MCS. Differences between values of 

E85–E10 are relatively low compared to differences 

between values of MCL.

Tables 6 and 7 also list the map scale, if known, 

that was used for manual measurements of MCS. 

While all the GIS quantifications of MCS listed in 

tables 6 and 7 were determined in this report using the 

same scale of topographic data and the same quantification method (Basinsoft), manual measurements of 

MCS listed in tables 6 and 7 were determined using 

various scales of topographic maps and different 

methods of measuring MCL.

Differences in MCS values between manual 

measurements or GIS quantifications depend primarily 

on two factors involving MCL. The first factor is the 

scale of topographic data used for the determination of 

MCL. Because MCL is a map-scale dependent 

measurement, the value of MCL is affected substantially by the scale of the topographic data used in the 

measurement. MCL is longer when measured using 

larger scale maps. The second factor is the method 

used to determine MCL. Given the same scale of 

main-channel line work, differences in MCL values 

are due to the amount of sinuosity that is included in 

the measurement. Different values of MCL may be 

obtained depending on whether dividers, graph paper, 

or GIS methods of measurement are used. The divider 

method of measuring MCL does not attempt to include 

all of the sinuosity of the main channel, and MCL 

values measured using dividers are typically less than 

values obtained using graph-paper or GIS methods of 

measurement. Because MCL is in the denominator of 

the MCS calculation (equation 1), the lesser the value 

determined for MCL, the greater the value calculated 

for MCS.

The graph-paper method of measuring MCL 

attempts to include the majority of the sinuosity of the 

main channel. The GIS technique for quantifying 

MCL includes all of the sinuosity of the main channel 

represented at the scale of the topographic data. 

Table 8 (in the “Supplemental Data” section at the end 

of the report) compares manual measurements and 

GIS quantifications of MCS using 1:24,000-scale 

topographic data for 23 streamflow-gaging stations in 

Iowa for which manual measurements of MCL were 

made using the graph-paper method. Mean and 

median percentage differences listed at the end of table 

8 between manual measurements and GIS quantifications of MCS are 0.6 and 1.3 percent, respectively. 

Mean and median differences between manual 

measurements and GIS quantifications of MCL are 

–0.3 and –1.2 percent, respectively. 

The Wilcoxon signed-rank test was computed 

(S-PLUS software; MathSoft, Inc., 1997) to determine 

the statistical difference between median manual 

measurements of MCS and median GIS quantifications of MCS for the 23 streamflow-gaging stations 

listed in table 8. The test indicates that there is not a 

significant difference between manual measurements 

and GIS quantifications of MCS for the gaging 

stations listed in table 8. Using a 95-percent level of 

significance for the two-tailed Wilcoxon signed-rank 

test, the p-value is 0.3303 (a p-value greater than 0.05 

generally indicates there is not a significant difference). This test indicates that manual measurements 

and GIS quantifications of MCS are comparable if 

made using the same scale of topographic data and if 

the graph-paper method is used to manually measure 

MCL.

MAIN-CHANNEL-SLOPE CURVES

 In response to the need to provide users with a 

simplified method for determining MCS values for 

sites located along large streams in Iowa in Regions 2 

and 3, MCS curves were developed for selected 

streams. GIS quantifications of MCS for selected sites 

along these streams were used to develop best-fit 

curves. The curve developed for each selected stream 
MAIN-CHANNEL-SLOPE CURVES 11

provides users with a simplified method for determining MCS values. 

Selection of Streams and Sites

Unregulated, large streams located in hydrologic 

Regions 2 and 3 with drainage areas greater than 100 

mi2

 were selected for inclusion in this report. Streams 

located within Region 1 were not included in this 

report because MCS is not included in the regression 

equations for Region 1 (table 1). Regulated stream 

reaches were not included in this report because the 

regression equations (tables 1–3) are not applicable for 

regulated streams. Streams overlying Regions 1 and 2 

were included for the reach within Region 2, if the 

reach length within Region 2 is longer than 5 mi. 

Figure 1 shows the location of the 138 streams 

selected for inclusion in this report. 

Main channels selected for streams in this report 

begin at the mouth for 123 of the streams. Main channels begin at the Iowa-Missouri State line for 10 of the 

streams that flow from Iowa to Missouri. Main channels begin at a county line for four of the streams 

(Chariton, Iowa, and South Fork Chariton Rivers, and 

West Fork Ditch; figs. 23, 52, 107, and 133, respectively) because of streamflow regulation downstream. 

The main channel of the Cedar River also begins at a 

county line. The Cedar River (fig. 22) downstream 

from the Buchanan-Black Hawk County line was not 

included in this report because drainage areas for this 

reach exceed the maximum value used to develop the 

regression equations for Region 2 (Eash, 2001). The 

Des Moines River was not included in this report 

because the reach within Region 2 is regulated.

Main-channel length was quantified for each 

selected stream from the beginning of the main 

channel to the basin divide. At each stream fork, the 

fork that contributes the greater drainage area was 

selected. Different stream names were encountered for 

different reaches of 17 of the main channels, and 

therefore, 17 of the MCS curves are labeled with more 

than one stream name.

Sites were selected along each of the 138 

selected streams for GIS quantifications of MCS. Sites 

were selected at all primary highways and county lines 

crossing the selected stream, and at all USGS streamflow-gaging stations located on the stream. Additional 

stream sites, located primarily at road crossings, also 

were selected to obtain points along the stream at 

about 5-mi intervals. For some streams with few road 

crossings, points are spaced at greater than 5-mi intervals; and for some streams where primary highway or 

county-line crossings, or gaging stations are located 

near each other, points are spaced at less than 

5-mi intervals. Figure 1 shows the location of the 

2,058 stream sites selected for inclusion in this report 

for the quantification of MCS.

Sites along the selected streams were selected 

for MCS quantifications if their drainage areas were 

greater than approximately 20–30 mi2

. Although 

MCL’s were quantified to basin divides, MCS values 

were not quantified for stream reaches with drainage 

areas less than approximately 20–30 mi2

. Stream sites 

used for MCS quantifications (shown as red dots in 

fig. 1) do not extend to the basin divides (upstream end 

of blue lines in fig. 1).

Development of Curves

Main-channel slope values were quantified 

using GIS at each of the selected sites along each of 

the selected streams. River miles were quantified from 

the beginning point of each stream to each site selected 

along the stream by use of a GIS program. River-mile 

and MCS values were plotted and a best-fit curve was 

developed for each stream. Figure 4 illustrates the 

development of a MCS curve for the Thompson River 

in south-central Iowa (fig. 117). The black dots show 

the river-mile and MCS values quantified using GIS 

for this report. The black line shows the best-fit MCS 

curve that was developed for this data set. 

Best-fit MCS curves were developed for all 138 

streams using a cubic smoothing spline (S-PLUS software; MathSoft, Inc., 1997). For one stream (North 

Fork Black Hawk Creek, fig. 82), a hand-drawn 

French curve was used in addition to the splined curve 

to the develop the best-fit curve. 

Best-fit curves were visually evaluated for each 

stream and modified as necessary by adjusting the 

degrees of freedom used in the spline. Best-fit curves 

were evaluated by (1) selecting the point or GIS value 

of MCS plotting the furthest from the curve, (2) determining a MCS value from the curve for the same river 

mile as the point, and (3) calculating a 100-year recurrence-interval discharge for both MCS values and their 

percentage difference. Upon evaluation of the fit of a 

curve, if the percentage difference between the 

100-year flood estimates was considered too large, the 
12 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

degrees of freedom were adjusted and the curve was 

replotted. 

For example, (1) the black dot shown in figure 4 

at river mile 105.94 plots the furthest away from the 

curve (black line) with an MCS value of 13.47 ft/mi; 

(2) the MCS value determined from the curve for the 

same river mile is 13.11 ft/mi; and (3) using a drainage 

area of 33.4 mi2 for this site and the regression equation for Region 2 for the 100-year recurrence-interval 

flood (table 2), the MCS value of the GIS quantification produces an estimate of 8,030 ft3/s and the MCS 

value of the curve produces an estimate of 7,960 ft3

/s. 

The difference between these two estimates is 0.9 

percent, which is considered acceptable accuracy for 

this report. 

A balance between smooth-looking curves and 

low-percentage differences was sought in the development of each curve. Absolute values of percentage 

differences between 100-year flood estimates determined using GIS values plotting the furthest from the 

curves and values from the curves were calculated for 

each of the 138 curves. The mean and median of the 

absolute values of percentage differences calculated 

for the 138 curves are both 1.1 percent. The minimum 

and maximum percentage differences are 0.0 and 

2.9 percent, respectively. These statistics indicate that 

100-year flood estimates calculated using MCS values 

determined from the best-fit curves should produce 

estimates similar to those calculated using MCS values 

quantified by GIS. 

For comparison purposes, the blue line in figure 

4 shows the MCS curve presented for the Thompson 

River by Schwob (1966) and Lara (1973). The blue 

dots show the river-mile and MCS values that were 

measured from 1:250,000-scale topographic maps. 

River miles measured using 1:250,000-scale data are 

listed across the top of figure 4 because they differ 

from river miles measured using 1:24,000-scale data. 

The MCS values determined for the Thompson River 

at Davis City streamflow-gaging station 

GIS quantification of main-channel slope using 1:24,000-scale 

digital topographic data

Curve fit to GIS quantifications

Curve fit to manual measurements [published in Schwob (1966) 

and Lara (1973)]

Curve fit to adjusted-GIS quantifications, adjustment factor 

+17.7 percent (figure 117)

Manual measurements of main-channel slope using 1:250,00-scale 

topographic maps

Thompson River at

Davis City gaging station

(06898000)

DISTANCE UPSTREAM FROM IOWA–MISSOURI STATE LINE, 

IN MILES, USING 1:24,000–SCALE DATA

DISTANCE UPSTREAM FROM IOWA–MISSOURI STATE LINE, 

IN MILES, USING 1:250,000–SCALE DATA

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

10 20 30 40 50 60 70 80 90

0 10 20 30 40 50 60 70 80 90

100 110

Figure 4. Examples of curves developed using main-channel-slope values determined from manual 

measurements, GIS quantifications, and adjusted-GIS quantifications.
MAIN-CHANNEL-SLOPE CURVES 13

(station number 06898000, fig. 117) are shown in the 

lower left-hand corner of figure 4 and are listed in 

table 7. 

The MCS curves developed for three of the 

streams (Middle Nodaway, South Raccoon, and West 

Fork Cedar Rivers; figs. 69, 109, and 132, respectively) are discontinuous because different main channels were used for different reaches with the same 

stream name. Figures 5 and 6 illustrate a discontinuous 

curve for the South Raccoon River in west-central 

Iowa. Figure 5 shows MCS curves and figure 6 shows 

main channels of selected streams in the Raccoon 

River Basin. The red, dark blue, and orange lines 

shown in figures 5 and 6 represent data for the South 

Raccoon River. The main channel of the South 

Raccoon River begins at river mile 30.46 and it is 

shown as the red line in figures 5 and 6. The main 

channel of the Middle Raccoon River begins at river 

mile 48.18 and it is shown as the pink line in figures 5 

and 6. Because the drainage area of the Middle 

Raccoon River (609 mi2) is greater than that for the 

South Raccoon River (377 mi2

) at their confluence, 

the main channel of the South Raccoon River downstream from the mouth of the Middle Raccoon River 

(red line in fig. 6) includes the Middle Raccoon River 

(pink line in figure 6). The red curve shown in figure 5 

for the South Raccoon River includes MCL and E85–

E10 quantifications for the Middle Raccoon River and 

this is the reason that the red and pink curves shown in 

figure 5 are continuous, and the red and dark blue 

curves are discontinuous. The main channel of Brushy 

Creek begins at river mile 73.49 and it is shown as 

the light blue line in figures 5 and 6. Because the 

drainage area of Brushy Creek (142 mi2

) is greater 

than that for the South Raccoon River at their confluence (122 mi2), the main channel of the South 

Raccoon River between the confluences with the 

Middle Raccoon River and Brushy Creek (dark blue 

line in fig. 6) includes Brushy Creek (light blue line in 

fig. 6). The dark blue curve in figure 5 includes MCL 

and E85–E10 quantifications for Brushy Creek and this 

is the reason the dark blue and light blue curves shown 

in figure 5 are continuous and the dark blue and orange 

curves are discontinuous.

DISTANCE UPSTREAM FROM MOUTH OF RACCOON RIVER, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

Raccoon and North Raccoon Rivers 

(figure 94)

Buttrick Creek (figure 19), tributary to 

North Raccoon River

Hardin Creek (figure 47), tributary to 

North Raccoon River

South Raccoon River (figure 109), reach 

downstream from confluence with 

Middle Raccoon River

Middle Raccoon River (figure 70)

Mosquito Creek (figure 74), tributary to 

Middle Raccoon River

Willow Creek (figure 139), tributary to 

Middle Raccoon River

South Raccoon River (figure 109), reach 

between confluences with Middle Raccoon 

River and Brushy Creek

Brushy Creek (figure 17)

South Raccoon River (figure 109), 

reach upstream from confluence 

with Brushy Creek

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

0 25 50 75 100 125 150 175 200 225

Figure 5. Main-channel-slope curves of selected streams in the Raccoon River Basin.
14 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

Base from U.S. Geological Survey digital data,

 1:24,000, 

Universal Transverse Mercator Projection,

 Zone 15, horizontal datum

North American Datum of 1927

94°45'

42°45'

41°45'

93°45'

Hardin Creek

Buttrick Creek

Raccoon

River

Raccoon River

Raccoon

South

Mosquito Creek

Willow Creek

Brushy Creek

Middle

Raccoon

River

North

River

0 10 20 MILES

0 10 20 KILOMETERS

3

1

2

Raccoon

 River Basin

IOWA

EXPLANATION

Drainage-basin boundary

Hydrologic region boundary

 and number

2

1

2

Des Moines Lobe landform

 region boundary

Figure 6. Main channels of selected streams in the Raccoon River Basin.
MAIN-CHANNEL-SLOPE CURVES 15

Figure 6 shows the boundary between hydrologic Regions 1 and 2 as a solid black line. The main 

channels of Hardin and Buttrick Creeks, which are 

both tributaries to the North Raccoon River, are shown 

as dashed green lines in figure 6. Figure 5 shows that 

MCS curves for these two creeks (dashed green lines) 

were only developed for the reaches located within 

Region 2 even though their main channels are in 

Regions 1 and 2. Likewise, MCS curves for other 

streams in Regions 1 and 2 were only developed for 

the reaches located in Region 2. Figure 1 shows 

several streams overlying Regions 1 and 2.

Figure 6 shows the boundary of the Des Moines 

Lobe landform region as a dashed black line. Main 

channels of the North Raccoon River and tributaries 

(green lines in fig. 6) are within the Des Moines Lobe 

landform region and the MCS curves for these streams 

(green lines in fig. 5) have relatively low MCS values 

compared to other streams in the Raccoon River Basin. 

Main channels of the South Raccoon River, upstream 

from the confluence with the Middle Raccoon River, 

and Brushy Creek (dark blue, orange, and light blue 

lines in fig. 6) are outside of the Des Moines lobe landform region and the MCS curves for these streams 

(dark blue, orange, and light blue lines in fig. 5) have 

relatively high MCS values compared to other streams 

in the Raccoon River Basin. Figures 5 and 6 illustrate 

the effect the Des Moines Lobe landform region has 

on MCS.

Adjustment of Curves

An adjustment was applied to all 138 MCS 

curves to compensate for differences in MCS values 

between manual measurements and GIS quantifications. Table 4 lists a statistical summary of percentage 

differences between flood-frequency discharge estimates calculated for Regions 2 and 3, using manual 

measurements and GIS quantifications of MCS for the 

same streamflow-gaging stations listed in tables 6 and 

7. Flood estimates were calculated for 2- to 500-year 

recurrence intervals, and percentage differences 

between the flood estimates were calculated. The 

summary statistics presented in table 4 list the mean, 

median, minimum, and maximum percentage differences for each recurrence interval.

For example, the first streamflow-gaging station 

listed in table 6 (Upper Iowa River at Decorah, station 

number 05387500) has an MCS value of 6.25 ft/mi for 

the manual measurement and an MCS value of 4.84 

ft/mi for the GIS quantification. Using the regression 

equation for Region 2 (table 2) for the 100-year recurrence-interval flood, the MCS value for the manual 

measurement produces an estimate of 27,700 ft3/s and 

the MCS value for the GIS quantification produces an 

estimate of 25,600 ft3/s. The difference between these 

two 100-year flood estimates is 8.2 percent. Flooddischarge estimates and percentage differences were 

calculated for all of the gaging stations listed in 

tables 6 and 7. For Region 2, mean and median 

percentage differences ranged between 5.0 to 5.3 and 

Table 4. Statistical summary of percentage differences between flood-frequency discharge 

estimates for selected streamflow-gaging stations in Regions 2 and 3 calculated using manual 

measurements and GIS quantifications of main-channel slope

Percentage difference for indicated recurrence interval (years)

2 5 10 25 50 100 200 500

[Region 2; number of streamflow gaging stations = 99 (table 6)]

Mean 5.2 5.0 5.0 5.0 5.1 5.3 5.2 5.2

Median 4.5 4.3 4.3 4.4 4.4 4.4 4.5 4.5

Minimum –15.6 –15.1 –15.1 –15.3 –15.4 –15.4 –15.6 –15.8

Maximum 61.9 59.2 59.4 60.2 60.6 61.4 61.9 62.9

[Region 3; number of streamflow-gaging stations = 27 (table 7)]

Mean 27.1 25.7 24.8 23.5 22.5 21.8 20.1 18.3

Median 17.3 16.6 16.0 15.5 15.1 14.1 13.1 12.3

Minimum –25.1 –24.3 –23.7 –22.8 –22.4 –21.2 –20.4 –18.8

Maximum 142.2 133.8 127.2 120.3 115.0 108.5 100.9 89.1
16 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

4.3 to 4.5 percent, respectively (table 4); and for 

Region 3, mean and median differences ranged 

between 18.3 to 27.1 and 12.3 to 17.3 percent, 

respectively (table 4). 

Because the application of GIS values of MCS 

in regression equations for Region 3 appears to 

substantially underestimate flood-frequency 

discharges compared to the manual values of MCS 

used to develop the equations, an adjustment factor 

was applied to the MCS curves developed for Region 

3. Although the Region 2 regression equations are not 

as sensitive as the Region 3 equations to differences in 

MCS values, an adjustment factor also was applied to 

the curves developed for Region 2 for consistency. The 

Region 3 equations are more sensitive to differences in 

MCS values because the exponents on the MCS variables are greater for Region 3 than for Region 2 (tables 

2 and 3).

The median percentage difference between 

manual and GIS values of MCS of 14.8 percent for 

Region 2 (table 6) and 17.7 percent for Region 3 

(table 7) were used for the adjustments. Figure 4 illustrates how the adjustment was applied to the MCS 

curve developed for the Thompson River (fig. 117). 

Following development of the original MCS curve 

(black line in fig. 4), MCS values used to plot this 

curve were multiplied by the adjustment factor to 

create an adjusted curve (red line in fig. 4). Because 

the majority of the Thompson River is within Region 

3, an adjustment of +17.7 percent was applied to the 

black line shown in figure 4. The adjusted curve parallels the original curve and plots with MCS values that 

are 17.7 percent greater than those originally quantified using GIS.

Table 5 lists a statistical summary of percentage 

differences between flood-frequency discharge estimates calculated for Regions 2 and 3, using manual 

measurements and adjusted-GIS quantifications of 

MCS for the same streamflow-gaging stations listed in 

tables 6–7. Table 5 is similar to table 4, except that 

GIS quantifications of MCS for Region 2 were 

adjusted by +14.8 percent from the GIS values listed 

in table 6 and GIS quantifications of MCS for Region 

3 were adjusted by +17.7 percent from the GIS values 

listed in table 7. 

For example, applying an adjustment factor of 

+14.8 percent to the GIS value of MCS for the first 

streamflow-gaging station listed in table 6 (Upper 

Iowa River at Decorah, station number 05387500) 

produces an adjusted-GIS value of 5.56 ft/mi. The 

100-year flood estimate using the adjusted-GIS value 

of MCS is 26,700 ft3

/s. Compared to the 27,700 ft3/s 

estimated for the manual measurement of MCS, the 

percentage difference between these two estimates is 

3.7 percent. 

Flood-frequency discharge estimates determined using adjusted-GIS values of MCS and 

percentage differences were calculated for all of the 

streamflow-gaging stations listed in tables 6 and 7. For 

Region 2, mean percentage differences ranged 

between 0.6 to 0.8 percent and median differences are 

0.0 percent (table 5). For Region 3, mean and median 

Table 5. Statistical summary of percentage differences between flood-frequency discharge 

estimates for selected streamflow-gaging stations in Regions 2 and 3 calculated using manual 

measurements and adjusted-GIS quantifications of main-channel slope

Percentage difference for indicated recurrence interval (years)

2 5 10 25 50 100 200 500

[Region 2; number of streamflow gaging stations = 99 (table 6); adjustment of +14.8 percent 

applied to GIS quantifications]

Mean 0.7 0.6 0.7 0.7 0.7 0.8 0.7 0.7

Median 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Minimum –19.2 –18.6 –18.6 –18.8 –18.9 –19.0 –19.2 –19.4

Maximum 55.0 52.6 52.8 53.5 53.9 54.5 55.0 55.8

[Region 3; number of streamflow-gaging stations = 27 (table 7); adjustment of +17.7 percent 

applied to GIS quantifications]

Mean 8.4 7.9 7.6 7.2 6.8 6.8 5.9 5.4

Median 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Minimum –36.2 –35.1 –34.1 –33.1 –32.3 –30.9 –29.5 –27.8

Maximum 105.9 100.5 96.0 90.9 87.4 82.7 76.5 68.5
MAIN-CHANNEL-SLOPE CURVES 17

differences ranged between 5.4 to 8.4 and 0.0 to 

0.3 percent, respectively (table 5). Table 5 indicates 

that MCS values determined from the adjusted curves 

and applied to the regression equations for Regions 2 

and 3 (tables 2 and 3) should calculate flood-frequency 

discharge estimates comparable to the estimates used 

to develop the regression equations. 

Presentation of Curves

Table 9 (in the “Supplemental Data” section at 

the end of the report) lists the river-mile and MCS 

values quantified for 2,058 selected sites along 138 

selected streams using GIS and 1:24,000-scale topographic data. Using the data values listed in table 9, 

best-fit curves were developed for each stream, and 

these curves were then adjusted for presentation. 

Figures 7–144 (in the “Supplemental Data” section at 

the end of the report) present MCS curves developed 

for the selected streams in Iowa. These curves were 

adjusted by 14.8 percent for streams in Region 2 and 

by 17.7 percent for streams in Region 3, and MCS 

values determined from these curves can be used in the 

regression equations for Regions 2 and 3 (tables 2 and 

3). Below each curve is a list of selected sites for the 

stream reach. Figure numbers and river miles listed in 

table 9 and figures 7–144 allow cross reference for 

determining MCS values quantified for selected 

stream sites.

An explanation of the list elements in the list of 

sites presented with each MCS curve in figures 7–144 

follows: 

River-mile values were quantified using 

1:24,000-scale topographic data and a GIS program. 

River miles measured from the mouth to the drainage 

divide provide a total length for the stream. 

Drainage area values, if known, are listed as 

square miles (mi2). 

If data or information for a list element is not 

determined or not available, a double dash (--) is 

listed. 

The site list provides information about the 

stream site such as a road name or county-line names. 

If an active or discontinued USGS streamflow-gaging 

station is located at the stream site, it is noted in parentheses with the USGS station number and information 

on the type of data collected at the gage. Information 

on the type of data collected at the gage, if known, is 

listed as one of four designations [cont, for a continuous-record gage; csg, for a high-flow, partial-record 

(crest-stage) gage; low, for a low-flow partial-record 

gage (Lara, 1979); and qw, for a water-quality gage]. 

Only the primary type of data collected for the gage is 

presented in the list, even though additional types of 

data may be available for the gage. For example, in 

figure 7 a gage is listed at river mile 10.30 at 4th Street 

crossing Bear Creek. The notation designating a 

gaging station at this site is “(05417700, cont).” This 

notation designates that the station number for this 

gage is 05417700 and the primary type of data 

collected at this site was continuous-record streamflow 

data. 

The gages listed in figures 7–144 also are listed 

in the USGS National Water Information System 

(NWIS) data base, and users may obtain additional 

information concerning types of data collected and the 

years for which data were collected at these gages 

from <http://waterdata.usgs.gov/ia/nwis/inventory> 

by selecting site number and entering the USGS 

station number on the following screen. The Bear 

Creek gage (station number 05417700, fig. 7) listed in 

the example above is a discontinued gage for which 

daily streamflow data were collected from 1957 to 

1976 and water-quality data were collected from 1966

to 1975. Information on the period of record of gages 

and other types of data collected at gages is not 

included in figures 7–144, and the user is referred to 

the NWIS data base for additional information for 

gages. No data type is listed for some gages in the 

NWIS data base; therefore, no data type is presented 

for some gages in figures 7–144. 

Stream sites presented in the lists are designated 

by a legal description derived from their respective 

locations using Public Land Survey System coordinates (township, range, section, and subsection). 

Within the section, the subsection in which the site is 

located is listed as one of nine designations (C, center; 

E, east; N, north; NE, northeast; NW, northwest; 

S, south; SE, southeast; SW, southwest; W, west). For 

example, 84N 1E 13 C refers to a stream-site location 

in Township 84 North, Range 1 East, in the center of 

section 13.

The public address “911” street names listed in 

figures 7–144 are the names obtained from the GIS 

data layer “Iowa DOT BaseRecord Data,” for the data 

layer item “NINEONEONE.” This data layer, 

provided to the USGS by Todd Noah, Assistant GIS 

Coordinator, Iowa Department of Transportation 

(written commun., April 2001), was updated through 
18 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

September 2000. No “911” street names were listed 

for some roads in the data layer, and therefore, no 

“911” street names are listed for some roads in 

figures 7–144.

The curves are presented alphabetically by 

stream names. For curves with more than one stream 

name, the downstream name is listed first in the table 

of contents. If a stream name is not found in the table 

of contents, figure 1 can be used to determine the 

downstream name. For example, an MCS value is 

needed for a stream site on the North Raccoon River, 

but the North Raccoon River is not listed alphabetically in the table of contents. Figure 1 shows the North 

Raccoon River is tributary to the Raccoon River. The 

table of contents lists an MCS curve for the Raccoon 

and North Raccoon Rivers in figure 94.

Where streams cross hydrologic region boundaries (Regions 1 and 2, or Regions 2 and 3) or the Des 

Moines Lobe landform region boundary, river miles 

and legal descriptions are shown in the list of sites 

with the figure to designate the locations of the 

boundary crossings. For example, figure 94 lists 

boundary crossings at river miles 30.56 and 220.67. 

These boundary crossings are included in the lists to 

aid users in the determination of hydrologic regions 

for the application of regression equations (tables 1–3) 

and for the determination of values for the DML variable for Region 2 (table 2). MCS values were not 

determined for the majority of the boundary crossings 

presented in the figure lists.

ESTIMATION OF FLOOD-FREQUENCY 

DISCHARGES USING MAIN-CHANNELSLOPE CURVES

 The MCS curves presented in figures 7–144 are 

applicable for determining MCS values for stream 

sites located along 138 streams in Iowa. The MCS 

values determined from the curves can be used in the 

regression equations for hydrologic Regions 2 and 3 

(tables 2 and 3) for the estimation of flood-frequency 

discharges. If a stream site within Region 2 or 3 is not 

located along one of the 138 selected streams or is 

located upstream from one of the MCS curves, a 

manual measurement of MCS using 1:24,000-scale 

topographic maps will be needed (see the five manual 

measurement steps listed in the section “Manual 

Measurements”). 

 Several techniques for estimating floodfrequency discharges for streams in Iowa are presented 

by Eash (2001), and the user is referred to the 2001 

flood-frequency estimation report for a complete 

description of the techniques. The techniques are 

presented for determining (1) regional regression estimates for ungaged sites on ungaged streams, (2) 

weighted estimates for gaged sites, and (3) weighted 

estimates for ungaged sites on gaged streams. The 

technique for determining regional regression estimates for ungaged sites on ungaged streams requires 

determining which of four possible examples applies 

to the location of the stream site and its basin. Illustrations for applying both the one-variable and multivariable regression equations are provided for the estimation techniques. The user also is referred to the 

section “Accuracy and Limitations of Regional 

Regression Estimates” in the 2001 report for a discussion on the applicability and accuracy of the regional 

equations listed in tables 1–3.

To determine an MCS value for a stream site 

using information in this report, the user first determines whether the stream site is located along a stream 

for which an MCS curve was developed. Figure 1 

shows, and the table of contents lists, streams for 

which MCS curves were developed. If an MCS curve 

is available for the stream site, the user next determines a river-mile value for the stream site. The 

following two examples illustrate the two possible 

methods for determining river-mile values and two of 

the techniques for estimating flood-frequency 

discharges.

Example 1

This example illustrates how a river-mile value 

can be determined for a stream site when the stream 

site is listed in figures 7–144. The 100-year flooddischarge estimate for U.S. Highway 34 crossing 

Walnut Creek northwest of Red Oak in Montgomery 

County, in the NE 1/4, sec. 23, T. 72 N., R. 39 W. will 

be determined. Figure 1 shows that Walnut Creek in 

Montgomery County is a stream included in the report 

and that its basin is located in hydrologic Region 2. 

The table of contents lists an MCS curve for Walnut 

Creek beginning in Fremont County as figure 124. An 

inspection of the stream site list in figure 124 shows 

U.S. Highway 34 listed as a stream site at river mile 

26.96. From the MCS curve (fig. 124) an MCS value 

of 6.65 ft/mi is determined for river mile 26.96. 
ESTIMATION OF FLOOD-FREQUENCY DISCHARGES USING MAIN-CHANNEL-SLOPE CURVES 19

 A drainage area of 108 mi2 is listed for the U.S. 

Highway 34 stream site in figure 124. Figure 2 shows 

that Walnut Creek basin is not in the Des Moines Lobe 

landform region. Streamflow-gaging stations listed in 

figure 124 do not indicate that Walnut Creek is a gaged 

stream (gage types of “cont” or “csg” indicate that a 

stream is gaged and that log-Pearson Type III floodfrequency estimates may be available for the site). 

This stream site is determined to be an ungaged site on 

an ungaged stream with a single-region basin that is 

not in the Des Moines Lobe landform region. The 

technique for estimating a flood-frequency discharge 

for this site is similar to example 1B in the 2001 report 

(Eash, 2001).

1. Figure 1 is used to determine which hydrologic 

region the basin is located within and select the 

appropriate multivariable regional regression 

equation from tables 1–3. If the basin is located 

within Region 1, only the one-variable equations 

are applicable.

2. The drainage area (DA), the main-channel slope 

(MCS), and the ratio of basin area within the Des 

Moines Lobe landform region to total area of the 

basin (DML) are determined for the stream site. 

Values of MCS can be determined for sites along 

selected streams in Iowa from figures 7–144 in 

this report. Measurements of DML can be 

obtained for stream sites located within Region 2 

by delineating the basin boundary for the stream 

site in figure 2 and determining the ratio of basin 

area within the Des Moines Lobe landform 

region to total area of the basin (shaded area 

shown in figure 2). 

For the U.S. Highway 34 stream site, the basin 

is located within Region 2. The 100-year flood-estimation equation listed for Region 2 in table 2 is:

Q100 = 531 DA.542 MCS.313 (DML+1)–.549 (2)

Drainage area for the basin was determined to 

be 108 mi2 and MCS for the basin was determined to 

be 6.65 ft/mi. Because the basin is located completely 

outside of the Des Moines Lobe landform region, the 

value for DML was determined to be 0.00. The flooddischarge estimate is calculated using equation 2:

Q100 = 531 (108).542 (6.65).313 (0.00 +1)–.549

Q100 = 12,200 ft3/s

Example 2

This example illustrates how a river-mile value 

can be determined for a stream site when a stream is 

included in figures 7–144 and the stream site is not 

included in the list of sites in the figure. The 50-year 

flood-discharge estimate for County Road E53 

crossing Buttrick Creek east of Jefferson in Greene 

County, in the NW 1/4, sec. 12, T. 83 N., R. 30 W. will 

be determined. Figure 1 shows that Buttrick Creek in 

Greene County is a stream included in the report and 

that its basin crosses a hydrologic region boundary 

(boundary between Regions 1 and 2). The table of 

contents lists an MCS curve for Buttrick Creek beginning in Greene County as figure 19. An inspection of 

the list of stream sites in figure 19 does not show 

County Road E53 included as a stream site. An inspection of maps and the list of stream sites in figure 19 

shows that U.S. Highway 30 is the nearest site listed 

with a river-mile value (river mile 8.75) to the County 

Road E53 site and that U.S. Highway 30 is upstream 

from County Road E53. Using a 1:24,000-scale topographic map to measure river miles along Buttrick 

Creek between County Road E53 and U.S. Highway 

30, a distance of 1.92 miles is measured between these 

two sites. A river-mile value of 6.83 is determined for 

County Road E53 crossing Buttrick Creek. From the 

MCS curve (fig. 19), an MCS value of 4.19 ft/mi is 

determined for river mile 6.83. 

A drainage area of 202 mi2 is listed for the U.S. 

Highway 30 stream site. The drainage area between 

County Road E53 and U.S. Highway 30 is measured 

to be 4.4 mi2

, and a drainage area of 206 mi2 is determined for County Road E53 crossing Buttrick Creek. 

Figure 2 shows that the entire Buttrick Creek Basin is 

in the Des Moines Lobe landform region. Streamflowgaging stations listed in figure 19 do not indicate that 

Buttrick Creek is a gaged stream (gage types of “cont” 

or “csg” indicate that a stream is gaged and that logPearson Type III flood-frequency estimates may be 

available for the site). This stream site is determined to 

be an ungaged site on an ungaged stream with a 

mixed-region basin that is in the Des Moines Lobe 

landform region. The technique for estimating a floodfrequency discharge for this site is similar to example 

4B in the 2001 report (Eash, 2001).
20 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

1. Figure 1 in this report is used to determine which 

hydrologic regions the basin is located within and 

select the appropriate multi-variable regression 

equation for each region from tables 1–3. If a 

portion of the basin is located within Region 1, 

then only the one-variable equations are applicable for the portion in Region 1.

2. The drainage area (DA), the main-channel slope 

(MCS), and the ratio of basin area within the Des 

Moines Lobe landform region to total area of the 

basin (DML) are determined for the stream site. 

The drainage area of the basin within each hydrologic region is determined. Values of MCS can be 

determined for stream sites along selected 

streams in Iowa from figures 7–144. Measurements of DML can be obtained for stream sites 

located within Region 2 by delineating the basin 

boundary for the stream site in figure 2 and determining the ratio of basin area within the Des 

Moines Lobe landform region to total area of the 

basin (shaded area shown in figure 2). 

Flood-frequency discharge estimates for stream 

sites with basins in more than one hydrologic region 

can be improved by calculating a mixed-region floodfrequency estimate. A flood-frequency estimate is 

calculated using each regional equation, and a mixedregion estimate is calculated from the regional estimates by using equation 3:

Qt(mr) = (DARegion x / DATotal) (Qt(Region x)) + 

(DARegion y / DATotal) (Qt(Region y)), (3)

where

Qt(mr) = the mixed-region discharge estimate for 

recurrence interval t, in cubic feet per 

second;

DARegion x, DARegion y = the area of the basin within 

Region x or y, respectively, in square 

miles;

DATotal = the total area of the basin, in square miles; 

and

Qt(Region x), Qt(Region y) = the regression estimate for 

recurrence interval t, computed using 

Region x or y regional equations, respectively, in cubic feet per second.

For the County Road E53 stream site, the basin 

is located within Regions 1 and 2. The 50-year floodestimation equations listed for Regions 1 and 2 in 

tables 1 and 2 are:

Q50 = 123 DA.666 (Region 1, only one-variable 

equation is applicable) (4)

Q50 = 430 DA.554 MCS.311 (DML+1)–.555

(Region 2) (5)

Drainage area for the basin was determined to 

be 206 mi2. By overlaying the basin boundary on 

figures 1 or 2 and by inspecting the list of stream sites 

in figure 19, it was determined that approximately 196 

mi2 of the drainage area is located within Region 1 and 

10 mi2 is located within Region 2. The MCS for the 

entire basin was determined to be 4.19 ft/mi. By overlaying the basin boundary on figure 2, it was determined that the entire drainage area is located within 

the Des Moines Lobe landform region. The DML was 

calculated to be 1.00. The flood-discharge estimate for 

each hydrologic region is calculated using equations 4 

and 5:

Q50 = 123 (206).666 (Region 1, only one-variable 

equation is applicable)

Q50 = 4,280 ft3/s (Region 1)

Q50 = 430 (206).554 (4.19).311 (1.00+1)–.555 (Region 2)

Q50 = 8,750 ft3/s (Region 2)

 The mixed-region (mr) estimate calculated 

from the two regional estimates using equation 3 is:

Q50(mr) = (196 / 206) (4,280) + (10 / 206) (8,750)

Q50(mr) = 4,500 ft3/s

 SUMMARY

Reliable estimates of flood-frequency 

discharges are essential for the economical planning 

and safe design of bridges, dams, levees, and other 

structures located along rivers and streams and for the 

effective management of flood plains. Multivariable 

regression equations for estimating flood-frequency 

discharges were previously developed for two of the 

three hydrologic regions defined for Iowa. The multivariable equations require the measurement of mainchannel slope (MCS), which is a difficult measurement to obtain for large streams using 1:24,000-scale 

topographic maps. In response to the need to provide 

users with a simplified method for determining MCS 

values for sites located along large streams in Iowa 

within Regions 2 and 3, the USGS, in cooperation with 

the Iowa Department of Transportation and the Iowa 
SUMMARY 21

Highway Research Board, initiated a statewide study 

in 2001.

This report (1) presents the results of geographic 

information system (GIS) techniques using 1:24,000-

scale digital topographic data to quantify MCS at 

2,058 selected sites along 138 large, unregulated 

streams in Iowa with drainage areas greater than 100 

mi2

 that are located in hydrologic Regions 2 and 3; (2) 

presents best-fit curves developed for selected streams 

showing relations between GIS quantifications of 

MCS and river miles, and river-mile information for 

selected stream sites; and (3) presents comparisons of 

manual measurements of MCS (used to develop 

regression equations) and GIS quantifications of MCS 

to determine whether adjustment factors are needed 

for applying the GIS values of MCS to the regression 

equations. If a stream site within Region 2 or 3 is not 

located along one of the streams selected for inclusion 

in this report or is located upstream from one of the 

MCS curves developed in this report, a manual 

measurement of MCS using 1:24,000-scale topographic data will be needed.

Two different methods have been used to 

measure MCS for streamflow-gaging stations in Iowa. 

MCS has been manually measured using topographic 

maps since the early 1960’s. Various scales of maps 

and methods of measuring main-channel length 

(MCL) have been used over the years in the measurement of MCS. These manual measurements of MCS 

were used to develop the multivariable regression 

equations for Regions 2 and 3. The technique for 

obtaining a manual, topographic-map measurement of 

MCS is illustrated for an example stream site. 

Main-channel slope has been quantified using 

GIS and Basinsoft (a computer program to quantify 

drainage-basin characteristics) and digital topographic 

data since the early 1990’s. Different scales of digital 

data and methods of measuring streambed elevations 

at 10 and 85 percent of the MCL (E10 and E85) have 

been used. Geographic information system was used 

to quantify MCS values for stream sites selected for 

this report because it provides an efficient and consistent method of quantification. The procedure for quantifying MCS using Basinsoft is described for an 

example stream site. 

A comparison of manual measurements and GIS 

quantifications of MCS for streamflow-gaging stations 

in Regions 2 and 3 indicates that manual measurements typically produce lesser values of MCL and 

greater values of MCS compared to GIS quantifications. Mean percentage differences between manual 

measurements and GIS quantifications of MCS are 

19.7 and 27.9 percent for Regions 2 and 3, respectively, and median differences are 14.8 and 17.7 

percent. Differences in MCS values obtained using 

manual measurements or GIS quantifications depend 

primarily on (1) the scale of topographic data used for 

the determination of MCL and (2) the method used to 

determine MCL. A comparison test indicates that there 

is not a significant difference between manual 

measurements and GIS quantifications of MCS if the 

same scale of topographic data is used and if the 

graph-paper method is used to manually measure 

MCL.

One hundred and thirty-eight unregulated 

streams located within Regions 2 and 3 with drainage 

areas greater than 100 mi2 were selected for inclusion 

in this report. Main channels were digitized for all 

138 streams using 1:24,000-scale topographic data. 

Sites were selected for GIS quantifications of MCS at 

about 5-mi intervals along each of the selected 

streams. The MCS values were quantified at 

2,058 selected sites along the 138 streams. River miles 

were quantified from the beginning point of each 

stream to each site selected along the stream by use of 

a GIS program. Data points for river-mile and MCS 

values were plotted and a best-fit MCS curve was 

developed for each stream. Visual fits of the curves to 

the data points were evaluated by comparing the 

percentage difference between 100-year flood 

discharges calculated using the MCS value of the data 

point plotting the furthest from each curve and the 

MCS value determined from each curve. The mean 

and median of the absolute values of the percentage 

differences calculated for the 100-year floods for the 

138 curves are both 1.1 percent, and the maximum 

difference is 2.9 percent.

An adjustment was applied to all 138 curves to 

compensate for differences in MCS values between 

manual measurements and GIS quantifications. 

Comparisons of percentage differences between floodfrequency discharges calculated using MCS values of 

manual measurements (values used to develop the 

regression equations for Regions 2 and 3) and GIS 

quantifications indicate that use of GIS values of MCS 

for Region 3 substantially underestimate flood 

discharges. Mean and median percentage differences 

for 2- to 500-year recurrence-interval flood discharges 
22 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

ranged from 5.0 to 5.3 and 4.3 to 4.5 percent, respectively, for Region 2 and ranged from 18.3 to 27.1 and 

12.3 to 17.3 percent for Region 3. The regression 

equations for Region 3 are more sensitive to differences in MCS values because the exponents on the 

MCS variables are greater for Region 3 than for 

Region 2. 

The MCS curves developed for streams located 

within Region 2 were adjusted by 14.8 percent, and 

streams located within Region 3 were adjusted by 

17.7 percent. Comparisons of percentage differences 

between flood discharges calculated using MCS 

values of manual measurements and GIS values 

adjusted by 14.8 percent for Region 2 and 17.7 percent 

for Region 3 indicate that the flood-discharge estimates are comparable. For Region 2, mean percentage 

differences for 2- to 500-year recurrence-interval flood 

discharges ranged between 0.6 to 0.8 percent and 

median differences were 0.0 percent. For Region 3, 

mean and median differences ranged between 5.4 to 

8.4 and 0.0 to 0.3 percent, respectively.

Figures at the end of the report present adjusted 

MCS curves for the 138 selected streams in Iowa. The 

MCS values determined from these curves can be used 

in the regression equations for Regions 2 and 3 for the 

estimation of flood-frequency discharges. A list of 

selected stream sites presented with each curve 

provides information about the sites that may aid users 

in the determination of river miles, drainage areas, the 

location of USGS streamflow-gaging stations, and the 

location of streams crossing hydrologic region boundaries or the Des Moines Lobe landform region 

boundary. Two examples are presented for determining river-mile and MCS values, and two techniques are presented for computing flood-frequency 

discharges. 

REFERENCES CITED

Alexander, T.W., and Wilson, G.L., 1995, Technique for 

estimating the 2- to 500-year flood discharges on 

unregulated streams in rural Missouri: U.S. Geological 

Survey Water-Resources Investigations Report 95–

4231, 33 p.

Benson, M.A., 1959, Channel-slope factor in floodfrequency analysis: American Society of Civil 

Engineers, separate no. 1994, 9 p.

Benson, M.A., 1962, Factors influencing the occurrence of 

floods in a humid region of diverse terrain: U.S. 

Geological Survey Water-Supply Paper 1580–B, 62 p.

Burmeister, I.L., 1970, The streamflow data program in 

Iowa: U.S. Geological Survey Open-File Report, 82 p.

Eash, D.A., 1993, Estimating design-flood discharges for 

streams in Iowa using drainage-basin and channelgeometry characteristics: U.S. Geological Survey 

Water-Resources Investigations Report 93–4062, 96 p.

Eash, D.A., 1994, A geographic information system procedure to quantify drainage-basin characteristics: Water 

Resources Bulletin, v. 30, no. 1, p. 1–8.

Eash, D.A., 2001, Techniques for estimating floodfrequency discharges for streams in Iowa: U.S. 

Geological Survey Water-Resources Investigations 

Report 00–4233, 88 p.

Harvey, C.A., and Eash, D.A., 1996, Description, instructions, and verification for Basinsoft, a computer 

program to quantify drainage-basin characteristics: 

U.S. Geological Survey Water-Resources Investigations Report 95–4287, 25 p.

Krug, W.R., Conger, D.H., and Gebert, W.A., 1992, Floodfrequency characteristics of Wisconsin streams: U.S. 

Geological Survey Water-Resources Investigations 

Report 91–4128, 185 p.

Lara, O.G., 1973, Floods in Iowa—Technical manual for 

estimating their magnitude and frequency: Iowa 

Natural Resources Council Bulletin 11, 56 p.

Lara, O.G., 1979, Annual and seasonal low-flow characteristics of Iowa streams: U.S. Geological Survey OpenFile Report 79–555, 507 p.

Lara, O.G., 1987, Method for estimating the magnitude and 

frequency of floods at ungaged sites on unregulated 

rural streams in Iowa: U.S. Geological Survey WaterResources Investigations Report 87–4132, 34 p.

Larimer, O.J., 1957, Drainage areas of Iowa streams: Iowa 

Highway Research Board Bulletin No. 7 (reprinted 

1974), 439 p.

Lorenz, D.L., Carlson, G.H., and Sanocki, C.A., 1997, 

Techniques for estimating peak flow on small streams 

in Minnesota: U.S. Geological Survey WaterResources Investigations Report 97–4249, 42 p.

Majure, J.J., and Soenksen, P.J., 1991, Using a geographic 

information system to determine physical basin characteristics for use in flood-frequency equations, in

Balthrop, B.H., and Terry, J.E., eds., U.S. Geological 

Survey National Computer Technology Meeting—

Proceedings, Phoenix, Ariz., November 14–18, 1988: 

U.S. Geological Survey Water-Resources Investigations Report 90–4162, p. 31–40.

MathSoft, Inc., 1997, S-Plus user’s guide, version 4.0: 

Seattle, Wash., Data Analysis Products Division.

Office of Water Data Coordination, 1978, Physical basin 

characteristics for hydrologic analysis, in National 

handbook of recommended methods for water-data 

acquisition: U.S. Geological Survey, Reston, Va., 

chap. 7, 38 p.
REFERENCES CITED 23

Ries, K.G., III, and Crouse, M.Y., comps., 2002, The 

National Flood Frequency Program, Version 3—A 

computer program for estimating magnitude and 

frequency of floods for ungaged sites, 2002: U.S. 

Geological Survey Water-Resources Investigations 

Report 02–4168, 42 p.

Sando, S.K., 1998, Techniques for estimating peak-flow 

magnitude and frequency relations for South Dakota 

streams: U.S. Geological Survey Water-Resources 

Investigations Report 98–4055, 48 p.

Schwob, H.H., 1966, Magnitude and frequency of Iowa 

floods: Iowa Highway Research Board Bulletin 28, 

parts I and II, 423 p.

Soenksen, P.J., Miller, L.D., Sharpe, J.B., and Watton, J.R., 

1999, Peak-flow frequency relations and evaluation of 

the peak-flow gaging network in Nebraska: U.S. 

Geological Survey Water-Resources Investigations 

Report 99–4032, 102 p.

Soller, D.R., and Packard, P.H., 1998, Digital representation 

of a map showing the thickness and character of 

Quaternary sediments in the glaciated United States 

east of the Rocky Mountains: U.S. Geological Survey 

Digital Data Series DDS–0038, 1 disc.
SUPPLEMENTAL DATA

SUPPLEMENTAL DATA 27

Table 6. Comparison of manual measurements and GIS quantifications of main-channel slope for selected streamflow-gaging stations in R[Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; DML, Des Moines Lobe, ratio of basin area within Des Moines Lobe landf

MCS, main-channel slope; MCL, main-channel length; E85, streambed elevation at 85 percent length of MCL; E10, streambed elevation at 10 percent length of MCL; mi2, s

%, percent; 250k, 1:250,000-scale topographic maps; --, not determined; 24kg, 1:24,000-scale topographic maps using graph-paper method to measure MCL; 24k, 1:24,000

divider method to measure MCL; mix, MCS determined using more than one scale of topographic maps or using topographic maps and water-surface-elevation profiles; pro

surface-elevation profile]

Station 

number Station name DA (mi2) DML

Manual measurements

GIS quantifications using

1:24,000-scale digital

topographic data

Map

scale

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

05387500 Upper Iowa River at Decorah, IA 511 0.00 250k 6.25 83.0 389 4.84 97.8 355 05388000 Upper Iowa River near Decorah, IA 568 0.00 250k 6.13 87.0 400 4.80 102 368 05388250 Upper Iowa River near Dorchester, IA 770 0.00 250k 5.68 -- -- 5.02 136 514 05389000 Yellow River at Ion, IA 221 0.00 250k 13.4 36.2 363 12.1 43.6 395 05411600 Turkey River at Spillville, IA 177 0.00 250k 6.93 32.2 167 5.43 40.2 164 05411700 Crane Creek near Lourdes, IA 75.8 0.00 250k 8.22 19.8 122 5.82 24.9 109 05412100 Roberts Creek above Saint Olaf, IA 70.7 0.00 24kg 8.13 30.5 186 7.86 30.6 180 05412500 Turkey River at Garber, IA 1,545 0.00 250k 5.58 112 469 4.64 144 501 05414500 Little Maquoketa River near Durango, IA 130 0.00 24k 17.6 24.0 316 17.1 24.1 309 05417000 Maquoketa River near Manchester, IA 305 0.00 24k 8.1 31.9 194 6.07 38.5 175 05417700 Bear Creek near Monmouth, IA 61.3 0.00 -- 8.24 32.5 201 6.04 33.5 152 05418450 North Fork Maquoketa River at Fulton, IA 516 0.00 24kg 4.57 88.1 302 4.51 88.4 299 05418500 Maquoketa River near Maquoketa, IA 1,553 0.00 24k 4.1 106 326 3.66 122 335 05420560 Wapsipinicon River near Elma, IA 95.2 0.00 -- 6.47 -- -- 4.26 40.2 129 05420640 Little Wapsipinicon Rivers at Elma, IA 37.3 0.00 250k 9.73 12.7 93 10.2 15.8 121 05420650 Little Wapsipinicon River near New 

Hampton, IA

95 0.00 -- 5.50 45.0 186 5.79 34.3 149 

05420690 East Fork Wapsipinicon River near New 

Hampton, IA

30.3 0.00 -- 32.0 -- -- 6.97 16.9 88.4 

05420850 Little Wapsipinicon River near Oran, IA 94.1 0.00 24k 4.70 -- -- 4.87 35.6 130 05421000 Wapsipinicon River at Independence, IA 1,048 0.00 250k 3.58 106 284 2.70 140 282 05422000 Wapsipinicon River near De Witt, IA 2,330 0.00 mix 2.69 230 466 2.20 279 461 05451500 Iowa River at Marshalltown, IA 1,532 0.81 mix 2.67 146 292 2.59 153 298 05451700 Timber Creek near Marshalltown, IA 118 0.00 250k 7.56 15.0 85 6.92 20.4 106 05452000 Salt Creek near Elberon, IA 201 0.00 250k 8.00 25.0 152 5.77 32.1 139 05452500 Iowa River near Belle Plaine, IA 2,455 0.51 pro 2.45 209 385 2.50 212 398 
28 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges 05453000 Big Bear Creek at Ladora, IA 189 0.00 250k 7.02 36.2 191 5.77 37.4 162 

05453100 Iowa River at Marengo, IA 2,794 0.45 pro 2.30 229 395 2.38 232 413 05454300 Clear Creek near Coralville, IA 98.1 0.00 -- 7.00 22.0 115 5.58 27.8 116 05455100 Old Mans Creek near Iowa City, IA 201 0.00 mix 3.91 387.6 113 4.10 44.3 136 05455140 North English River near Montezuma, IA 31 0.00 -- 5.67 -- -- 9.69 11.3 82.4 05455150 North English River near Malcom, IA 34 0.00 -- 5.67 20.0 85.0 8.24 12.4 76.6 05455200 North English River near Guernsey, IA 68.7 0.00 -- 7.59 -- -- 6.92 21.0 109 05455210 North English River at Guernsey, IA 81.5 0.00 -- 5.63 -- -- 6.51 23.0 112 05455500 English River at Kalona, IA 573 0.00 250k 4.20 65.8 207 3.79 72.8 207 05457700 Cedar River at Charles City, IA 1,054 0.27 250k 3.45 92.8 240 2.98 106 238 05458000 Little Cedar River near Ionia, IA 306 0.00 mix 5.05 62.2 236 3.94 79.7 236 05458500 Cedar River at Janesville, IA 1,661 0.17 mix 2.96 138 307 2.74 155 319 05458900 West Fork Cedar River at Finchford, IA 846 0.37 mix 5.00 69.0 261 3.79 90.5 257 05460500 Shellrock River at Marble Rock, IA 1,318 0.65 mix 4.10 78.4 241 3.57 87.7 235 05462000 Shellrock River at Shell Rock, IA 1,746 0.49 mix 3.60 109 293 3.21 120 290 05463000 Beaver Creek at New Hartford, IA 347 0.15 250k 7.60 42.8 243 5.56 55.2 230 05463090 Black Hawk Creek at Grundy Center, IA 56.9 0.00 24kg 7.01 18.3 96 6.81 19.2 98.2 05463500 Black Hawk Creek at Hudson, IA 303 0.00 250k 6.20 33.4 154 4.27 46.1 148 05464000 Cedar River at Waterloo, IA 5,146 0.29 mix 2.80 158 332 2.72 175 358 05464560 Prairie Creek at Blairstown, IA 87 0.00 -- 7.02 -- -- 6.03 18.1 81.9 05464640 Prairie Creek at Fairfax, IA 178 0.00 24kg 4.14 37.0 115 3.91 37.9 111 05470000 South Skunk River near Ames, IA 315 1.00 mix 7.34 48.2 265 6.39 49.5 237 05470500 Squaw Creek at Ames, IA 204 1.00 250k 8.87 32.8 218 6.04 39.5 179 05471000 South Skunk River below Squaw Creek near 

Ames, IA

556 1.00 250k 6.63 53.7 267 5.91 55.2 245 

05471050 South Skunk River at Colfax, IA 803 0.96 mix 4.64 85.3 297 4.18 87.1 273 05471200 Indian Creek near Mingo, IA 276 1.00 250k 6.36 45.3 216 5.48 53.9 222 

Table 6. Comparison of manual measurements and GIS quantifications of main-channel slope for selected streamflow-gaging stations in R[Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; DML, Des Moines Lobe, ratio of basin area within Des Moines Lobe landf

MCS, main-channel slope; MCL, main-channel length; E85, streambed elevation at 85 percent length of MCL; E10, streambed elevation at 10 percent length of MCL; mi2, s

%, percent; 250k, 1:250,000-scale topographic maps; --, not determined; 24kg, 1:24,000-scale topographic maps using graph-paper method to measure MCL; 24k, 1:24,000

divider method to measure MCL; mix, MCS determined using more than one scale of topographic maps or using topographic maps and water-surface-elevation profiles; pro

surface-elevation profile]

Station 

number Station name DA (mi2) DML

Manual measurements

GIS quantifications using

1:24,000-scale digital

topographic data

Map

scale

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)
SUPPLEMENTAL DATA 29

05471500 South Skunk River near Oskaloosa, IA 1,635 0.68 mix 3.63 129 351 3.28 131 322 05472090 North Skunk River near Baxter, IA 52.2 0.09 24kg 11.1 22.0 183 9.05 22.7 154 05472500 North Skunk River near Sigourney, IA 730 0.01 250k 3.29 97.6 241 2.76 110 227 05473000 Skunk River at Coppock, IA 2,916 0.38 pro? 2.22 210 350 2.25 212 358 05473300 Cedar Creek near Batavia, IA 252 0.00 24kg 3.81 32.6 93 3.63 34.3 93 05473400 Cedar Creek near Oakland Mill, IA 530 0.00 24kg 2.57 80.5 155 2.59 82.5 160 05473500 Big Creek near Mount Pleasant, IA 106 0.00 250k 5.32 20.5 82 4.12 25.3 78 05474000 Skunk River at Augusta, IA 4,303 0.26 pro? 1.92 264 380 1.90 266 379 05481950 Beaver Creek near Grimes, IA 358 1.00 -- 4.40 68.8 224 4.33 71.2 231 05482300 North Raccoon River near Sac City, IA 700 0.95 250k 3.50 42.3 111 2.56 61.7 118 05482500 North Raccoon River near Jefferson, IA 1,619 0.97 250k 2.98 121 270 2.56 135 260 05483450 Middle Raccoon River near Bayard, IA 375 0.62 24kg 4.25 61.2 195 4.41 61.6 204 05484000 South Raccoon River at Redfield, IA 994 0.42 250k 5.12 81.2 312 4.18 95.2 298 05484500 Raccoon River at Van Meter, IA 3,441 0.80 250k 2.71 173 353 2.44 199 364 05485640 Fourmile Creek at Des Moines, IA 92.7 1.00 24k 7.62 30.3 173 7.33 29.7 163 05486000 North River near Norwalk, IA 349 0.00 mix 7.11 60.0 320 5.42 83.8 341 05486490 Middle River near Indianola, IA 503 0.00 mix 5.68 87.7 374 4.68 113 396 05488000 White Breast Creek near Knoxville, IA 380 0.00 250k 4.48 52.0 175 4.08 80.7 247 05489150 Little Muchakinock Creek at Oskaloosa, IA 9.12 0.00 24kg 16.3 6.28 77 16.3 6.46 79 05489490 Bear Creek at Ottumwa, IA 22.9 0.00 24kg 11.8 13.5 120 13.8 14.8 153 06483270 Rock River at Rock Rapids, IA 788 0.20 250k 6.33 64.2 305 3.97 3.97 301 06483430 Otter Creek at Sibley, IA 29.9 0.25 -- 10.0 14.2 106 6.38 23.0 110 06483460 Otter Creek near Ashton, IA 88.0 0.12 -- 9.65 21.1 153 5.95 33.6 150 06483500 Rock River near Rock Valley, IA 1,592 0.14 250k 5.79 87.2 379 4.05 128 390 06600100 Floyd River at Alton, IA 268 0.00 mix 5.49 48.2 199 4.25 59.6 190 06600300 West Branch Floyd River near Struble, IA 180 0.00 24k 4.18 37.6 118 4.19 37.4 118 06600500 Floyd River at James, IA 886 0.00 mix 4.38 90.8 298 3.79 106 301 

Table 6. Comparison of manual measurements and GIS quantifications of main-channel slope for selected streamflow-gaging stations in R[Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; DML, Des Moines Lobe, ratio of basin area within Des Moines Lobe landf

MCS, main-channel slope; MCL, main-channel length; E85, streambed elevation at 85 percent length of MCL; E10, streambed elevation at 10 percent length of MCL; mi2, s

%, percent; 250k, 1:250,000-scale topographic maps; --, not determined; 24kg, 1:24,000-scale topographic maps using graph-paper method to measure MCL; 24k, 1:24,000

divider method to measure MCL; mix, MCS determined using more than one scale of topographic maps or using topographic maps and water-surface-elevation profiles; pro

surface-elevation profile]

Station 

number Station name DA (mi2) DML

Manual measurements

GIS quantifications using

1:24,000-scale digital

topographic data

Map

scale

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)
30 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges 06602020 West Fork ditch at Hornick, IA 403 0.00 250k 6.50 56.0 273 4.81 71.8 259 

06605000 Ocheyedan River near Spencer, IA 426 0.46 250k 5.65 55.0 233 5.07 63.4 241 06605600 Little Sioux River at Gillette Grove, IA 1,334 0.66 mix 2.98 79.2 177 2.23 101 169 06605850 Little Sioux River at Linn Grove, IA 1,548 0.62 mix 1.81 102 138 2.00 129 193 06606600 Little Sioux River at Correctionville, IA 2,500 0.39 mix 1.99 169 253 1.66 210 261 06606700 Little Sioux River near Kennebec, IA 2,738 0.36 mix 1.93 203 294 1.51 247 280 06607200 Maple River at Mapleton, IA 669 0.00 250k 4.83 67.8 246 3.34 84.9 212 06608500 Soldier River at Pisgah, IA 407 0.00 250k 8.11 49.2 299 6.54 54.9 269 06609500 Boyer River at Logan, IA 871 0.00 250k 3.56 92.9 248 3.28 102 252 06609560 Willow Creek near Soldier, IA 29.1 0.00 24kg 13.2 13.6 135 13.0 13.6 119 06610520 Mosquito Creek near Earling, IA 32.0 0.00 mix 13.4 -- -- 10.6 12.8 102 06610600 Mosquito Creek at Neola, IA 131 0.00 mix 7.30 -- -- 8.12 37.9 231 06807410 West Nishnabotna River at Hancock, IA 609 0.00 250k 5.65 51.6 219 5.09 62.3 238 06808500 West Nishnabotna River at Randolph, IA 1,326 0.00 250k 4.78 91.1 327 4.12 106 329 06809210 East Nishnabotna River near Atlantic, IA 436 0.00 250k 5.56 45.7 191 5.01 53.4 201 06809500 East Nishnabotna River at Red Oak, IA 894 0.00 250k 4.68 74.2 261 4.22 84.5 268 06810000 Nishnabotna River above Hamburg, IA 2,806 0.00 250k 4.44 108 359 3.89 124 362 06811840 Tarkio River at Stanton, IA 49.3 0.00 -- 11.2 15.7 132 7.99 18.1 108 06818598 Platte River near Stringtown, IA 51.7 0.00 24kg 7.08 17.0 90 7.10 17.2 91 06818750 Platte River near Diagonal, IA 217 0.00 24kg 5.75 38.0 164 4.74 38.2 136 06819185 East Fork 102 River at Bedford, IA 85.4 0.00 250k 7.50 24.0 135 5.45 25.2 103 06819190 East Fork 102 River near Bedford, IA 92.1 0.00 250k 7.75 26.0 151 5.76 27.8 120 

Mean Median Minimum Maximum 

Table 6. Comparison of manual measurements and GIS quantifications of main-channel slope for selected streamflow-gaging stations in R[Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; DML, Des Moines Lobe, ratio of basin area within Des Moines Lobe landf

MCS, main-channel slope; MCL, main-channel length; E85, streambed elevation at 85 percent length of MCL; E10, streambed elevation at 10 percent length of MCL; mi2, s

%, percent; 250k, 1:250,000-scale topographic maps; --, not determined; 24kg, 1:24,000-scale topographic maps using graph-paper method to measure MCL; 24k, 1:24,000

divider method to measure MCL; mix, MCS determined using more than one scale of topographic maps or using topographic maps and water-surface-elevation profiles; pro

surface-elevation profile]

Station 

number Station name DA (mi2) DML

Manual measurements

GIS quantifications using

1:24,000-scale digital

topographic data

Map

scale

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)
SUPPLEMENTAL DATA 31

Table 7. Comparison of manual measurements and GIS quantifications of main-channel slope for selected streamflow-gaging stations in Regio[Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; MCS, main-channel slope; MCL, main-channel length; E85, streambed elevation 

E10, streambed elevation at 10 percent length of MCL; mi2, square miles; ft/mi, feet per mile; %, percent; 250k, 1:250,000-scale topographic maps; --, not determined; 24kg, 1:24

using graph-paper method to measure MCL; 62.5k, 1:62,500-scale topographic maps]

Station 

number Station name DA (mi2) Manual measurements

GIS quantifications using

1:24,000-scale digital

topographic data

Map 

scale

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

05487470 South River near Ackworth, IA 460 250k 6.68 41.9 210 6.18 48.4 224 05487600 South White Beast Creek near Osceola, IA 28 -- 17.0 -- -- 12.9 9.79 95 305487800 White Breast Creek at Lucas, IA 128 -- 7.90 28.6 169 5.24 42.3 166 505487980 White Breast Creek near Dallas, IA 342 -- 4.78 41.2 148 4.23 71.3 226 105488200 English Creek near Knoxville, IA 90.1 24kg 5.63 33.6 142 5.60 34.0 143 05488620 Coal Creek near Albia, IA 13.5 24kg 19.8 6.66 99 19.1 6.78 97 05489000 Cedar Creek near Bussey, IA 374 250k 5.74 43.0 185 4.34 54.9 179 305489350 South Avery Creek near Blakesburg, IA 33.1 24kg 11.2 14.2 120 10.8 14.3 116 05491000 Sugar Creek near Keokuk, IA 105 250k 5.76 31.7 137 4.25 40.4 129 305494300 Fox River at Bloomfield, IA 87.7 250k 8.30 19.0 118 7.05 21.9 116 105494500 Fox River at Cantril, IA 161 250k 6.82 41.0 210 5.63 44.1 186 205495000 Fox River at Wayland, MO 400 -- 4.50 -- -- 4.04 92.0 279 105495600 South Wyaconda River near West Grove, IA 4.69 -- 26.9 -- -- 19.6 4.24 62 305496000 Wyaconda River above Canton, MO 393 -- 4.50 -- -- 4.08 80.9 248 105497000 North Fabius River at Monticello, MO 452 -- 4.80 -- -- 3.99 76.0 227 206897000 East Fork Big Creek near Bethany, MO 95 -- 7.24 -- -- 5.14 42.4 163 406897950 Elk Creek near Decatur City, IA 52.5 24kg 11.6 13.5 117 15.6 10.4 121 -206898000 Thompson River at Davis City, IA 701 250k 3.51 84.3 222 3.01 110 248 106898400 Weldon River near Leon, IA 104 250k 12.0 -- -- 6.28 27.4 129 906899000 Weldon River at Mill Grove, MO 494 -- 5.05 50.2 190 4.60 61.4 211 06900000 Medicine Creek near Galt, MO 225 -- 5.00 -- -- 4.58 55.8 192 06903400 Chariton River near Chariton, IA 182 -- 6.00 -- -- 2.43 48.9 89.1 1406903500 Honey Creek near Russell, IA 13.2 62.5k 12.2 7.43 68 9.75 9.04 66 206903700 South Fork Chariton River near Promise City, IA 168 24kg 5.82 25.9 113 5.79 27.1 118 06903900 Chariton River near Rathbun, IA 549 250k 3.7 -- -- 2.12 91.8 146 706903990 Cooper Creek at Centerville, IA 47.8 24kg 6.81 24.9 127 7.00 26.2 137 -06904000 Chariton River near Centerville, IA 708 250k 3.42 53.8 184 2.03 108 165 6

Mean 2Median 1Minimum -2Maximum 14
32 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges Table 8. Comparison of manual measurements and GIS quantifications of main-channel slope using 1:24,000-scale topographic data for se

stations in Iowa [Station number, U.S. Geological Survey streamflow-gaging station number; DA, drainage area; MCS, main-channel slope; MCL, main-channel length, E85, streambed elev

MCL; E10, streambed elevation at 10 percent length of MCL; Region, hydrologic region; mi2, square miles; ft/mi, feet per mile; %, percent] Station number Station name Region DA (mi2) Manual measurementsa GIS quantificationsb P

m

MCS (ft/mi) MCL (mi)

E85–E10

(ft)

MCS

(ft/mi)

MCL

(mi)

E85–E10

(ft)

MC

(%

05412100 Roberts Creek above Saint Olaf 2 70.7 8.13 30.5 186 7.86 30.6 180 3.05418450 North Fork Maquoketa River at Fulton 2 516 4.57 88.1 302 4.51 88.4 299 1.05463090 Black Hawk Creek at Grundy Center 2 56.9 7.01 18.3 96 6.81 19.2 98.2 2.05464640 Prairie Creek at Fairfax 2 178 4.14 37.0 115 3.91 37.9 111 5.05472090 North Skunk River near Baxter 2 52.2 11.1 22.0 183 9.05 22.7 154 22.05473300 Cedar Creek near Batavia 2 252 3.81 32.6 93 3.63 34.3 93 5.05473400 Cedar Creek near Oakland Mills 2 530 2.57 80.5 155 2.59 82.5 160 -0.05481680 Beaver Creek at Beaver 1 38.5 8.32 18.8 117 9.30 17.0 119 -10.05482135 North Raccoon River near Newell 1 233 3.37 31.2 79 3.28 31.5 77 2.05483318 Brushy Creek near Templeton 2 45 8.60 15.5 100 9.91 15.7 116 -13.05483450 Middle Raccoon River near Bayard 2 375 4.25 61.2 195 4.41 61.6 204 -3.05483600 Middle Raccoon River at Panora 2 440 4.07 74.4 227 3.70 73.6 204 10.05488200 English Creek near Knoxville 3 90.1 5.63 33.6 142 5.60 34.0 143 0.05488620 Coal Creek near Albia 3 13.5 19.8 6.66 99 19.1 6.78 97 3.05489150 Little Muchakinock Creek at Oskaloosa 2 9.12 16.3 6.28 77 16.3 6.46 79 0.05489350 South Avery Creek near Blakesburg 3 33.1 11.2 14.2 120 10.8 14.3 116 3.05489490 Bear Creek at Ottumwa 2 22.9 11.8 13.5 120 13.8 14.8 153 -14.06609560 Willow Creek near Soldier 2 29.1 13.2 13.6 135 13.0 13.6 132 1.06818598 Platte River near Stringtown 2 51.7 7.08 17.0 90 7.10 17.2 91 -0.06818750 Platte River near Diagonal 2 217 5.75 38.0 164 4.74 38.2 136 21.06897950 Elk Creek near Decatur City 3 52.5 11.6 13.5 117 15.6 10.4 121 -25.06903700 South Fork Chariton River near Promise City 3 168 5.82 25.9 113 5.79 27.1 118 0.06903990 Cooper Creek at Centerville 3 47.8 6.81 24.9 127 7.00 26.2 137 -2.

Mean 0Median 1Minimum -25Maximum 22

aMain-channel length measured using graph paper method (Eash, 2001).bMain-channel slope measured using Basinsoft (Harvey and Eash, 1996).
SUPPLEMENTAL DATA 33

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

Figure 7. Bear Creek, beginning at mouth in Jackson County.

0.00 6.09 5.06 6.28 10.30 6.04 16.55 6.82 29.47 10.14

1.06 6.28 6.65 5.79 12.94 6.49 23.33 8.02 43.82 --

Figure 8. Bear and North Bear Creeks, beginning at mouth of Bear Creek in Allamakee County.

0.00 18.04 4.17 18.57 11.60 20.80 14.98 20.58 24.20 --

0.48 18.27 9.17 20.37 11.91 20.34 18.72 29.07 -- --

Figure 9. Beaver Creek, beginning at mouth in Black Hawk County.

0.00 5.10 15.35 5.75 31.11 6.92 48.70 -- -- --

1.55 5.03 18.39 6.02 36.64 7.52 48.71 7.75 -- --

4.76 5.10 23.18 6.30 43.02 8.09 53.67 7.96 -- --

9.87 5.56 24.57 6.48 45.52 7.70 65.04 -- -- --

Figure 10. Beaver Creek, beginning at mouth in Polk County.

0.00 3.98 16.66 4.71 31.75 4.97 50.90 7.52 60.47 9.30

1.80 4.21 19.25 4.72 34.08 5.10 55.76 8.10 77.49 --

6.26 4.33 22.24 4.75 40.40 5.74 59.04 8.46 -- --

12.96 4.45 25.20 4.79 47.18 6.71 59.75 -- -- --

Figure 11. Big Bear Creek, beginning at mouth in Iowa County.

0.00 5.23 3.45 5.20 14.99 6.36 24.54 6.89 34.55 8.28

1.06 5.16 8.10 5.77 18.12 6.51 28.87 7.97 36.91 10.54

2.25 5.30 11.42 5.51 22.57 6.71 30.98 7.42 45.54 --

Figure 12. Big Creek, beginning at mouth in Henry County.

0.00 3.92 11.65 3.73 24.84 4.12 31.38 4.69 50.18 --

1.84 3.86 14.84 3.86 27.37 3.94 34.91 5.76 -- --

6.80 3.81 19.60 4.14 27.50 3.93 39.15 7.43 -- --

Figure 13. Big Creek, beginning at mouth in Linn County.

0.00 8.68 3.13 10.03 10.72 14.02 21.71 -- -- --

1.11 9.20 7.63 11.85 14.95 17.46 -- -- -- --

Figure 14. Big Muddy Creek, beginning at mouth in Clay County.

0.00 5.72 3.55 6.23 14.91 7.59 26.77 9.65 -- --

0.81 5.86 7.59 6.34 20.28 7.87 34.96 -- -- --

3.19 6.29 11.46 6.32 23.44 9.26 -- -- -- --

Figure 15. Black Hawk Creek, beginning at mouth in Black Hawk County.

0.00 3.68 5.90 4.09 19.46 4.49 33.75 6.02 45.90 8.27

0.57 3.74 6.41 4.13 23.16 4.74 36.82 5.71 58.65 --

0.81 3.83 12.52 4.27 27.81 5.28 39.42 6.81 -- --

Figure 16. Boyer River, beginning at mouth in Pottawattamie County.

0.00 3.29 15.70 3.28 40.33 3.31 62.28 3.53 88.76 4.99

3.30 3.35 18.93 3.36 43.26 3.35 65.20 3.50 94.62 5.26

3.81 3.34 23.56 3.36 48.44 3.55 69.31 3.77 100.01 7.28

3.97 3.35 27.80 3.56 50.59 3.27 72.18 4.00 105.50 9.59

5.23 3.33 30.02 3.41 52.14 3.48 75.28 4.05 109.28 12.86

6.42 3.39 34.03 3.19 55.57 3.61 79.88 4.65 118.19 --

11.14 3.29 34.31 3.20 58.32 3.46 84.42 4.44 -- --

Figure 17. Brushy Creek, beginning at mouth in Guthrie County.

0.00 6.94 7.65 7.01 21.44 8.08 26.93 8.41 35.34 9.91

0.98 7.11 11.68 7.35 24.95 8.26 28.72 8.33 40.22 12.25

3.47 7.22 18.01 7.64 25.47 8.71 33.34 9.52 51.01 --

Figure 18. Buffalo and East Branch Buffalo Creeks, beginning at mouth of Buffalo Creek in Jones County.

0.00 4.55 13.30 4.57 26.83 4.72 42.87 4.87 54.42 5.90

0.43 4.62 15.01 4.64 28.88 4.67 47.69 5.13 61.71 6.29

5.19 4.60 20.08 4.67 32.72 4.60 48.69 4.89 78.54 --

8.29 4.72 24.46 4.80 36.69 4.80 51.52 5.06 -- --
34 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 19. Buttrick Creek, beginning at mouth in Greene County.

0.00 3.99 8.75 3.39 10.26 3.44 -- -- -- --

3.36 4.00 10.22 3.44 50.15 -- -- -- -- --

Figure 20. Cedar Creek, beginning at mouth in Henry County.

0.00 2.38 20.65 2.63 40.76 3.37 56.96 4.42 72.72 6.70

4.43 2.59 27.24 2.94 44.59 3.60 60.06 4.98 75.35 8.11

10.16 2.49 33.13 3.18 50.05 3.77 64.21 5.06 77.80 7.81

15.19 2.52 37.30 3.40 52.65 3.63 68.49 5.24 86.93 --

Figure 21. Cedar Creek, beginning at mouth in Mahaska County.

0.00 3.87 8.80 4.34 23.22 5.30 37.60 7.10 51.64 10.77

2.66 3.86 13.35 4.59 29.31 5.57 42.45 7.52 63.75 --

3.19 3.90 18.17 5.20 34.20 6.67 45.64 8.25 -- --

Figure 22. Cedar River, beginning at Buchanan-Black Hawk County line.

0.00 2.59 33.35 2.71 57.42 2.75 87.51 2.98 126.64 2.95

6.65 2.61 34.26 2.72 58.88 2.79 95.24 2.98 131.56 2.93

14.72 2.63 34.69 2.73 63.67 2.82 105.08 3.14 132.95 2.87

21.72 2.68 42.75 2.73 70.61 2.78 113.73 2.88 134.36 2.87

26.28 2.72 46.07 2.74 77.20 2.92 114.97 2.92 141.02 2.96

26.84 2.73 46.59 2.74 82.08 2.94 118.24 2.72 145.25 3.19

30.60 2.67 46.88 2.75 83.79 2.88 122.99 2.82 201.68 --

Figure 23. Chariton River, beginning at Wayne-Lucas County line.

0.00 2.30 23.98 2.57 43.64 2.60 55.00 5.24 -- --

7.63 2.33 30.59 2.38 44.80 2.84 55.48 5.46 -- --

12.19 2.42 35.25 2.31 49.54 3.66 58.45 6.58 -- --

17.83 2.43 39.06 2.39 54.79 5.15 66.74 -- -- --

Figure 24. Chequest Creek, beginning at mouth in Van Buren County.

0.00 5.04 11.06 5.55 20.91 6.48 27.78 7.05 48.96 --

3.20 5.05 17.34 5.91 21.18 6.50 33.88 7.58 -- --

Figure 25. Clanton and North Fork Clanton Creeks, beginning at mouth of Clanton Creek in Warren County.

0.00 7.04 4.11 7.92 20.57 9.22 32.35 7.41 -- --

1.37 7.29 10.15 7.75 24.32 9.73 45.57 -- -- --

3.31 7.71 15.97 8.82 29.88 8.04 -- -- -- --

Figure 26. Clear Creek, beginning at mouth in Johnson County.

0.00 4.87 4.80 5.65 10.27 5.93 20.00 9.28 -- --

0.44 4.95 5.79 5.74 13.48 7.35 22.41 12.14 -- --

2.79 5.58 6.50 5.93 16.10 8.84 30.60 -- -- --

Figure 27. Crane Creek, beginning at mouth in Black Hawk County.

0.00 2.96 3.23 2.89 10.32 3.23 17.53 3.62 27.63 5.51

0.24 2.98 5.04 2.77 14.61 3.52 21.46 4.21 39.81 --

Figure 28. Crane Creek, beginning at mouth in Fayette County.

0.00 4.45 13.44 4.14 27.78 4.67 40.72 5.82 56.04 11.13

4.31 4.32 17.63 4.43 31.71 4.74 46.13 6.79 65.66 --

7.29 4.31 20.63 4.17 35.43 4.84 50.10 7.62 -- --

11.04 4.22 23.20 4.09 39.47 5.60 51.81 7.96 -- --

Figure 29. Crooked and West Fork Crooked Creeks, beginning at mouth of Crooked Creek in Jefferson County.

0.00 2.91 3.47 2.91 20.37 3.33 41.24 4.95 59.48 --

0.56 2.94 9.13 3.34 26.52 3.61 46.50 6.31 -- --

1.06 2.97 15.17 3.11 35.05 3.82 51.06 7.48 -- --

Figure 30. Deep Creek, beginning at mouth in Jackson County.

0.00 5.63 3.12 5.69 7.99 6.26 18.28 8.13 -- --

2.59 5.54 4.62 5.95 14.22 8.07 31.07 -- -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 35

Figure 31. East Boyer River, beginning at mouth in Crawford County.

0.00 8.54 2.13 8.90 10.62 11.11 23.06 -- -- --

0.34 8.84 6.21 9.49 13.27 11.95 -- -- -- --

Figure 32. East Branch West Nishnabotna River, beginning at mouth in Pottawattamie County.

0.00 6.23 5.21 5.69 13.48 6.67 24.71 9.21 37.11 19.59

1.71 5.85 5.75 5.80 17.98 7.44 28.59 10.46 42.90 --

3.00 5.49 10.28 6.51 21.06 8.84 32.36 13.62 -- --

Figure 33. East Fork Crooked Creek, beginning at mouth in Washington County.

0.00 2.39 7.86 2.73 18.86 4.81 27.04 9.94 -- --

3.31 2.62 12.75 3.52 22.93 7.08 35.21 -- -- --

Figure 34. East Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor County.

0.00 5.88 6.51 5.76 10.30 5.90 17.69 6.29 34.35 --

4.41 5.89 9.13 5.45 14.99 6.61 22.11 8.69 -- --

Figure 35. East Fork Wapsipinicon River, beginning at mouth in Bremer County.

0.00 4.49 8.83 4.69 17.76 4.97 29.76 6.50 37.28 8.92

2.67 4.46 13.37 4.67 22.59 5.26 33.63 6.97 50.55 --

Figure 36. East Nishnabotna River, beginning at mouth in Fremont County.

0.00 3.88 31.95 4.23 59.66 5.11 83.99 5.55 105.83 7.97

3.55 3.66 38.14 4.22 62.37 4.85 84.54 5.63 110.31 9.94

4.69 3.70 39.35 4.13 66.87 5.00 87.69 6.02 115.24 13.78

10.67 3.78 41.83 4.17 69.24 5.01 91.35 6.49 122.68 --

12.53 4.04 46.27 4.65 74.33 5.10 91.61 6.50 -- --

17.04 4.11 51.34 4.52 74.64 5.14 96.40 6.29 -- --

22.35 4.08 52.31 4.54 78.33 5.04 97.51 6.43 -- --

28.12 4.28 57.86 4.58 81.48 5.77 102.32 7.29 -- --

Figure 37. East Nodaway River, beginning at mouth in Page County.

0.00 4.06 12.40 3.92 26.28 4.17 41.13 3.69 75.06 --

0.67 4.12 14.51 3.99 30.49 4.27 46.56 4.01 -- --

2.71 3.76 18.79 4.08 36.79 3.79 53.48 5.73 -- --

7.16 3.84 21.91 4.19 37.73 3.88 60.14 7.99 -- --

Figure 38. English Creek, beginning at mouth in Marion County.

0.00 4.54 12.73 5.60 21.22 7.25 34.39 12.72 -- --

2.27 4.62 15.10 5.71 28.32 9.51 46.68 -- -- --

8.54 5.25 19.43 6.33 31.18 10.57 -- -- -- --

Figure 39. English and North English Rivers, beginning at mouth of English River in Washington County.

0.00 3.44 21.93 4.01 38.85 4.92 52.25 5.84 68.84 6.92

3.18 3.40 25.05 4.07 41.51 5.17 58.52 6.15 70.90 7.33

3.87 3.43 28.35 4.13 43.08 5.37 60.27 6.49 73.65 7.37

6.66 3.39 33.61 4.40 45.04 5.29 63.48 6.25 77.45 8.24

15.44 3.77 36.60 4.44 46.80 5.60 65.04 5.93 78.50 9.69

17.03 3.79 38.09 4.85 48.44 5.53 66.84 6.51 89.85 --

Figure 40. Farm Creek, beginning at mouth in Mills County.

0.00 8.74 4.52 9.80 9.90 19.62 -- -- -- --

2.48 8.94 5.77 10.67 18.11 -- -- -- -- --

Figure 41. Flint Creek, beginning at mouth in Des Moines County.

0.00 5.80 6.31 6.30 14.12 7.86 22.02 13.68 -- --

0.97 6.11 10.14 7.91 18.68 11.03 30.66 -- -- --

Figure 42. Flood Creek, beginning at mouth in Butler County.

0.00 4.74 12.45 4.88 30.28 6.33 40.87 8.43 -- --

2.82 4.73 18.80 5.00 34.71 6.40 52.69 -- -- --

7.67 4.68 25.09 5.64 38.07 6.93 53.45 -- -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
36 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 43. Floyd River, beginning at mouth in Woodbury County.

0.00 3.75 13.86 3.93 36.28 3.98 60.24 4.62 84.71 6.00

0.07 3.76 17.27 3.97 40.26 3.94 63.39 4.67 86.06 5.80

0.41 3.77 23.12 3.84 45.34 4.03 67.84 5.24 88.66 6.54

0.49 3.77 26.76 3.90 49.75 4.00 71.16 5.23 95.36 6.75

4.14 3.87 27.90 3.97 55.31 4.25 74.05 5.36 101.35 7.66

7.23 3.89 31.32 4.00 56.25 4.31 77.88 5.74 108.86 8.61

8.94 3.79 32.25 3.90 56.75 4.36 84.15 6.06 114.87 --

Figure 44. Fourmile Creek, beginning at mouth in Polk County.

0.00 7.31 5.16 7.33 13.47 8.30 23.54 8.58 -- --

1.93 -- 6.21 7.36 16.76 8.48 34.83 -- -- --

3.55 7.34 8.78 7.69 18.19 8.50 -- -- -- --

Figure 45. Fox River, beginning at Iowa-Missouri State line in Van Buren County.

0.00 4.93 13.82 5.60 26.35 6.95 39.12 9.76 -- --

1.37 5.02 16.63 5.56 30.19 6.81 41.62 10.18 -- --

4.87 5.10 17.97 5.84 30.98 7.05 43.70 10.64 -- --

8.70 5.63 22.12 5.91 35.11 8.31 52.84 -- -- --

Figure 46. Grand River, beginning at Iowa-Missouri State line in Ringgold County.

0.00 6.26 6.92 6.97 16.77 7.63 23.95 7.99 -- --

0.22 6.30 9.65 7.07 19.07 7.92 28.69 8.29 -- --

3.99 6.73 12.40 7.09 21.19 7.98 42.48 -- -- --

Figure 47. Hardin Creek, beginning at mouth in Greene County.

0.00 3.29 5.95 3.18 12.11 2.79 15.41 2.71 55.57 --

2.64 3.05 8.20 3.05 13.75 2.60 18.36 2.54 -- --

Figure 48. Hartgrave Creek, beginning at mouth in Butler County.

0.00 6.39 2.97 6.51 7.71 7.01 10.22 7.23 -- --

1.11 6.27 5.52 6.72 8.99 7.05 45.73 -- -- --

Figure 49. Honey Creek, beginning at mouth in Marshall County.

0.00 7.97 10.47 8.60 17.96 10.28 25.31 11.37 -- --

2.99 8.38 13.60 8.82 19.91 9.97 33.49 -- -- --

6.43 8.59 15.11 -- 23.47 11.64 35.97 -- -- --

Figure 50. Indian Creek, beginning at mouth in Cass County.

0.00 6.00 3.68 6.82 15.05 7.96 22.06 9.59 28.09 12.21

0.80 6.57 7.89 7.04 15.67 8.19 25.68 9.95 38.42 --

1.62 6.52 11.01 7.43 18.69 8.13 27.13 11.63 -- --

Figure 51. Indian and East Indian Creeks, beginning at mouth of Indian Creek in Jasper County.

0.00 5.25 8.53 5.50 14.47 5.52 27.30 5.94 41.74 6.58

0.24 5.28 8.80 -- 18.10 5.73 30.30 5.98 48.49 9.02

2.22 5.10 11.52 5.48 20.55 5.65 33.90 5.98 52.87 11.92

4.69 5.14 11.67 5.50 23.39 5.97 38.63 6.36 65.46 --

Figure 52. Iowa River, beginning at Johnson-Iowa County line.

0.00 2.27 50.82 2.45 95.58 2.54 127.57 2.43 164.94 1.39

2.17 2.29 56.32 2.47 100.36 2.59 131.77 2.48 167.64 1.40

12.15 2.33 61.11 2.49 101.09 2.52 137.63 2.45 172.90 1.41

21.83 2.38 69.99 2.54 107.27 2.52 140.48 -- 175.66 --

33.23 2.42 75.01 2.54 111.79 2.60 144.44 2.32 253.53 --

41.38 2.50 81.66 2.55 115.22 2.57 149.98 2.20 -- --

42.00 2.42 83.22 2.57 116.74 2.48 155.48 1.80 -- --

42.67 2.45 88.44 2.54 121.29 2.45 161.98 1.33 -- --

46.32 2.42 91.50 2.55 125.09 2.40 162.44 1.33 -- --

Figure 53. Kanaranzi Creek, beginning at mouth in Lyon County.

0.00 5.25 3.80 5.35 7.80 5.49 -- -- -- --

1.88 5.28 6.46 5.52 66.07 -- -- -- -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 37

Figure 54. Keg Creek, beginning at mouth in Mills County.

0.00 5.18 9.32 5.98 20.83 6.80 38.24 6.90 46.10 8.15

1.82 5.33 13.47 6.68 24.89 6.78 42.78 7.59 49.57 9.34

4.33 5.56 15.68 6.78 27.78 6.35 43.50 7.60 52.42 9.00

5.87 5.47 17.75 6.81 33.72 7.11 45.55 7.69 64.80 --

Figure 55. Little Cedar River, beginning at mouth in Chickasaw County.

0.00 3.94 12.89 3.93 29.18 4.29 45.34 4.50 66.86 7.23

1.24 4.01 13.21 3.94 30.61 4.40 51.10 4.86 87.33 --

4.20 4.01 17.89 4.11 36.65 4.66 55.43 5.23 -- --

7.61 3.94 23.58 4.10 39.61 4.73 60.98 5.69 -- --

Figure 56. Little Maquoketa River, beginning at mouth in Dubuque County.

0.00 12.97 6.84 17.15 15.39 25.18 20.14 34.58 -- --

4.13 15.46 9.84 18.82 17.92 30.12 30.22 -- -- --

Figure 57. Little Rock River, beginning at mouth in Lyon County.

0.00 4.57 9.65 4.82 24.08 6.00 39.86 6.62 77.57 --

0.76 4.50 13.69 4.96 28.33 6.45 44.44 6.53 -- --

2.91 4.46 17.21 5.22 33.48 6.36 47.30 7.00 -- --

5.07 4.67 21.07 6.11 36.81 6.39 50.68 7.52 -- --

Figure 58. Little Sioux River, beginning at mouth in Harrison County.

0.00 1.67 32.12 1.59 82.69 1.84 123.61 1.93 185.26 2.45

0.47 1.68 33.22 1.60 86.32 1.82 126.79 1.88 191.71 2.78

1.11 1.64 38.03 1.54 89.81 1.91 131.77 1.96 197.59 2.88

5.89 1.62 43.72 1.66 96.94 1.87 139.38 2.00 202.03 2.99

8.83 1.64 46.93 1.68 97.95 1.84 148.43 2.01 207.41 3.04

13.41 1.57 52.06 1.72 98.84 1.81 152.45 2.06 211.23 3.03

17.24 1.59 58.80 1.66 105.80 1.87 159.11 2.11 216.85 3.33

21.66 1.51 59.84 1.66 111.09 1.95 164.22 2.29 220.69 3.60

21.86 1.51 67.31 1.80 117.42 1.92 167.38 2.23 224.29 3.74

23.69 1.53 69.97 1.77 119.77 1.88 175.24 2.27 226.26 3.79

28.47 1.56 72.14 1.79 120.89 1.90 180.27 2.28 268.49 --

Figure 59. Little Turkey River, beginning at mouth in Fayette County.

0.00 4.39 11.78 4.47 22.31 5.24 30.04 5.10 41.96 7.46

4.34 4.57 14.16 5.03 24.42 5.03 32.90 4.70 44.36 9.43

8.27 4.37 19.42 4.86 25.91 4.88 37.64 6.01 53.25 --

Figure 60. Little Wapsipinicon River, beginning at mouth in Buchanan County.

0.00 4.21 11.22 4.59 19.19 4.87 31.85 6.09 40.55 7.27

0.61 4.18 11.47 4.55 25.96 5.29 35.99 6.37 54.81 --

4.55 4.26 16.14 4.78 27.71 5.36 38.74 7.18 -- --

Figure 61. Little Wapsipinicon River, beginning at mouth in Chickasaw County.

0.00 5.08 7.71 5.79 18.69 7.43 26.27 10.23 42.04 --

5.07 5.41 13.51 6.15 23.43 8.56 32.23 13.71 -- --

Figure 62. Long and East Long Creeks, beginning at mouth of Long Creek in Decatur County.

0.00 6.00 11.29 7.68 19.04 9.30 33.11 -- -- --

5.14 6.13 16.26 8.24 21.39 9.92 -- -- -- --

Figure 63. Long and South Fork Long Creeks, beginning at mouth of Long Creek in Louisa County.

0.00 3.74 9.04 4.09 25.37 5.40 35.56 6.32 -- --

1.58 3.72 16.31 4.82 28.21 5.58 37.42 6.47 -- --

4.95 4.06 19.43 5.50 31.06 5.68 50.35 -- -- --

Figure 64. Lost Island Outlet, Pickerel Run, and Joint drainage ditch 61, beginning at mouth of Lost Island Outlet in Clay County.

0.00 5.63 5.13 5.45 12.89 7.11 22.94 9.61 -- --

3.20 5.63 6.41 5.47 15.38 7.41 29.60 -- -- --

4.89 5.41 10.29 6.22 19.45 9.50 -- -- -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
38 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 65. Lytle Creek, beginning at mouth in Jackson County.

0.00 7.14 5.94 8.40 16.69 11.38 20.12 12.49 34.01 --

1.38 7.61 14.52 10.60 17.02 11.90 22.52 13.92 -- --

Figure 66. Maple River, beginning at mouth in Monona County.

0.00 3.33 15.98 3.34 32.61 3.60 54.33 4.05 78.86 6.15

1.18 3.37 17.70 3.25 37.10 3.53 60.28 4.31 85.44 9.01

1.92 3.39 22.28 3.43 41.79 3.70 63.27 4.87 88.59 10.80

6.43 3.34 26.62 3.40 46.56 3.81 67.98 4.76 100.85 --

11.26 3.38 30.47 3.70 48.85 3.80 71.57 5.13 -- --

Figure 67. Maquoketa River, beginning at mouth in Jackson County.

0.00 3.33 40.26 3.94 81.50 5.14 109.40 6.44 131.32 8.23

2.20 3.35 44.30 3.96 83.00 5.12 111.18 6.07 134.74 8.87

7.15 3.39 47.06 4.07 87.54 5.29 113.26 6.30 138.98 8.77

11.22 3.47 53.45 4.14 92.17 5.39 114.76 6.34 139.73 9.36

19.51 3.47 59.02 4.19 94.40 5.92 117.04 6.84 149.66 --

27.60 3.66 61.86 4.38 97.09 4.98 121.34 7.47 -- --

31.72 3.67 66.84 4.58 101.58 5.38 125.52 7.34 -- --

Figure 68. Maynes Creek, beginning at mouth in Butler County.

0.00 7.32 5.26 7.53 10.49 7.67 43.53 -- -- --

0.79 7.30 9.55 7.51 16.11 8.06 -- -- -- --

Figure 69. Middle Nodaway River, beginning at mouth in Montgomery County.

0.00 4.72 12.51 5.33 25.99 6.24 34.01 5.47 60.62 --

0.79 4.79 15.25 5.55 27.06 6.19 38.03 6.02 --

2.91 4.84 18.72 5.81 28.91 6.72 40.60 6.37 -- --

6.86 4.92 20.76 6.22 28.91 5.06 46.30 7.28 -- --

8.52 5.14 22.58 6.15 29.44 5.10 49.42 8.90 -- --

Figure 70. Middle Raccoon River, beginning at mouth in Dallas County.

0.00 4.08 18.16 3.70 40.65 4.55 55.22 5.33 76.56 9.36

1.56 4.05 19.25 3.95 44.14 4.50 58.39 5.89 78.37 9.75

7.55 4.14 26.74 4.29 48.41 4.87 63.55 6.97 82.49 12.69

8.60 4.11 30.23 4.41 48.80 4.93 68.63 8.22 91.80 --

12.88 3.45 34.36 4.09 51.98 5.28 72.24 8.77 -- --

Figure 71. Middle River, beginning at mouth in Warren County.

0.00 4.38 28.80 4.78 57.72 4.97 84.29 5.36 109.21 8.35

5.24 4.60 29.40 4.81 60.87 4.90 89.87 5.68 113.85 10.50

9.31 4.63 35.36 4.93 66.30 4.84 94.77 5.86 127.60 --

13.15 4.70 40.99 5.00 69.46 4.68 99.47 6.84 -- --

14.79 4.68 45.29 5.18 73.06 4.92 104.15 7.34 -- --

19.82 4.72 49.29 4.91 75.10 4.97 107.23 7.76 -- --

23.62 4.74 53.09 4.77 78.38 5.33 108.02 8.42 -- --

Figure 72. Mill Creek, beginning at mouth in Cherokee County.

0.00 4.22 11.80 4.10 30.30 5.10 45.39 7.88 65.72 --

2.75 4.25 17.67 4.43 37.20 5.97 50.01 10.86 -- --

7.38 4.10 24.15 4.71 41.42 6.91 54.03 13.44 -- --

Figure 73. Minerva Creek, beginning at mouth in Marshall County.

0.00 8.60 8.09 9.38 12.19 9.97 20.64 11.12 36.40 --

3.96 8.81 11.57 -- 18.22 10.22 24.72 11.67 -- --

Figure 74. Mosquito Creek, beginning at mouth in Dallas County.

0.00 4.27 4.80 3.95 16.84 4.23 31.94 7.31 44.68 --

0.32 -- 9.70 4.21 22.04 5.01 33.98 8.92 -- --

2.03 4.00 13.46 4.19 26.96 5.33 38.97 17.83 -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 39

Figure 75. Mosquito Creek, beginning at mouth in Pottawattamie County.

0.00 6.33 7.84 6.34 24.64 8.12 31.93 7.76 49.99 11.53

2.96 6.27 11.93 7.19 25.50 8.20 36.92 9.13 62.51 --

3.48 6.33 13.18 7.09 26.68 8.30 40.77 9.53 -- --

5.15 6.27 16.02 7.11 29.11 7.89 45.32 10.24 -- --

7.06 6.41 19.26 7.44 29.68 8.34 49.73 10.63 -- --

Figure 76. Mud Creek, beginning at mouth in Lyon County.

0.00 5.35 4.69 5.66 13.98 5.66 23.99 7.72 -- --

0.78 5.44 8.22 5.48 17.20 6.33 25.28 7.96 -- --

2.36 5.51 10.98 5.47 18.66 6.33 42.47 -- -- --

Figure 77. Mud Creek, beginning at mouth in Muscatine County.

0.00 3.05 5.09 3.80 11.31 3.86 18.65 5.80 27.89 --

1.79 3.52 9.54 4.12 16.36 5.57 23.13 10.17 -- --

Figure 78. Mud Creek, beginning at mouth in Scott County.

0.00 5.06 4.79 5.86 10.25 7.78 21.91 -- -- --

1.72 5.19 7.48 6.68 13.00 9.88 -- -- -- --

Figure 79. Nishnabotna and West Nishnabotna Rivers, beginning at Iowa-Missouri State line in Fremont County.

0.00 3.96 21.42 4.12 46.20 4.54 75.94 4.80 105.18 6.07

1.33 3.84 23.44 4.24 49.53 4.56 76.51 4.83 109.33 6.83

3.84 3.89 27.68 4.10 52.96 4.64 81.42 4.96 111.03 7.64

5.45 3.91 30.25 4.07 57.59 4.84 87.57 5.34 111.50 8.28

8.19 4.03 34.22 4.33 59.40 4.95 92.84 5.64 114.00 8.84

12.60 4.16 38.91 4.39 65.57 5.09 97.17 5.95 119.14 13.92

16.15 4.15 44.71 4.44 73.16 5.01 101.19 6.28 127.90 --

Figure 80. Nodaway and West Nodaway Rivers, beginning at Iowa-Missouri State line in Page County.

0.00 4.33 12.00 4.68 26.33 4.99 44.29 5.49 62.94 7.66

2.93 4.40 20.17 4.83 29.82 4.78 48.16 6.06 66.78 9.00

6.09 4.47 24.03 4.73 32.47 5.02 51.74 6.24 78.17 --

11.51 4.63 25.66 4.94 37.33 5.08 58.12 7.56 -- --

Figure 81. North Cedar Creek, beginning at mouth in Marion County.

0.00 5.63 9.80 6.79 15.33 8.00 23.79 9.57 37.65 --

3.28 6.00 14.69 7.65 20.13 9.22 28.27 13.19 -- --

Figure 82. North Fork Black Hawk Creek, beginning at mouth in Grundy County.

0.00 3.51 5.52 4.18 12.15 4.23 25.09 -- -- --

2.23 4.12 7.72 4.43 15.95 10.03 -- -- -- --

Figure 83. North Fork Maquoketa River, beginning at mouth in Jackson County.

0.00 4.33 12.37 4.57 44.24 5.48 62.33 7.05 72.57 7.90

0.27 4.35 16.94 4.65 44.58 5.55 63.90 7.11 79.15 8.33

5.93 4.50 22.12 5.08 47.50 5.58 69.41 7.34 80.67 10.47

8.24 4.51 29.40 5.13 57.30 6.28 71.52 7.35 96.61 --

Figure 84. North River, beginning at mouth in Polk County.

0.00 4.38 22.83 5.42 40.61 6.43 65.67 6.60 95.65 11.07

4.06 4.53 26.27 5.53 45.81 6.87 71.73 6.17 106.62 --

4.98 4.57 31.53 5.76 50.50 7.24 78.66 6.43 -- --

9.03 4.67 36.60 6.09 53.96 7.30 85.01 7.24 -- --

15.99 4.95 37.44 6.16 59.77 7.56 90.78 8.30 -- --

Figure 85. North Skunk River, beginning at mouth in Keokuk County.

0.00 2.49 40.34 3.27 65.61 3.85 92.27 5.84 106.64 9.22

3.62 2.52 41.28 3.34 72.72 4.34 92.72 5.97 106.95 9.05

7.55 2.70 48.13 3.29 76.49 4.53 93.76 6.04 112.03 10.63

19.60 2.76 53.61 3.51 80.84 4.91 95.07 6.30 118.04 13.87

25.66 2.95 57.27 3.51 82.01 4.78 99.28 7.09 125.21 --

33.80 3.16 63.44 3.81 86.34 5.42 104.09 8.53 129.65 --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
40 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 86. Ocheyedan River, beginning at mouth in Clay County.

0.00 4.88 12.87 5.05 22.94 5.55 32.84 5.31 40.98 5.85

4.88 5.07 16.83 5.19 24.32 5.43 34.61 5.37 68.29 --

8.37 5.03 20.34 5.30 28.25 5.63 36.67 5.44 -- --

Figure 87. Old Mans Creek, beginning at mouth in Johnson County.

0.00 4.04 3.14 4.03 15.82 4.22 28.28 5.42 39.81 7.80

1.10 3.85 8.83 4.10 22.51 4.98 32.32 6.61 43.09 9.33

1.34 3.87 12.17 4.33 25.71 5.28 36.35 6.88 53.09 --

Figure 88. Otter Creek, beginning at mouth in Buchanan County.

0.00 6.98 7.82 8.28 14.78 9.82 28.98 -- -- --

4.63 7.71 11.36 8.99 18.99 11.37 -- -- -- --

Figure 89. Otter Creek, beginning at mouth in Lyon County.

0.00 5.14 7.68 5.45 20.07 5.55 29.78 5.95 40.35 6.38

1.71 5.17 12.37 5.54 23.90 5.72 35.25 6.18 45.35 6.67

5.97 5.30 15.03 5.77 26.89 5.86 38.64 6.34 63.35 --

Figure 90. Otter Creek, beginning at mouth in Warren County.

0.00 5.36 7.01 5.68 18.27 7.64 23.17 9.53 30.00 12.79

4.79 5.95 12.17 6.70 19.64 7.95 28.09 11.35 41.37 --

Figure 91. Pigeon Creek, beginning at mouth in Pottawattamie County.

0.00 8.07 3.12 9.05 16.27 10.57 23.14 11.84 33.59 14.36

0.91 8.60 7.23 9.14 18.43 10.63 26.59 11.34 44.08 --

1.39 8.69 11.04 9.93 19.10 11.35 30.49 11.76 -- --

Figure 92. Platte River, beginning at Iowa-Missouri State line in Taylor County.

0.00 3.65 10.37 4.03 20.45 4.92 32.57 5.33 40.40 7.12

4.19 3.97 13.04 4.34 24.80 5.46 34.09 5.66 44.00 8.41

6.75 4.15 17.36 4.74 28.92 5.36 38.40 7.10 55.55 --

Figure 93. Prairie Creek, beginning at mouth in Linn County.

0.00 3.91 5.16 4.05 13.94 4.57 28.07 5.65 37.32 7.87

2.59 4.10 7.22 3.95 17.24 4.28 30.31 6.03 41.67 10.01

3.18 4.15 10.51 3.91 22.03 4.70 34.81 6.86 48.41 --

Figure 94. Raccoon and North Raccoon Rivers, beginning at mouth of Raccoon River in Polk County.

0.00 2.41 44.07 2.47 96.71 2.54 144.88 2.48 179.78 2.50

2.56 2.42 49.70 2.47 101.60 2.53 147.82 2.51 186.20 2.55

8.60 2.43 54.87 2.58 106.89 2.55 152.69 2.64 190.95 2.86

13.95 2.44 60.26 2.63 111.53 2.56 157.10 2.63 196.54 3.28

15.66 2.46 64.49 2.61 117.06 2.63 161.76 2.49 201.09 3.59

24.38 2.41 69.14 2.64 120.00 2.62 163.44 2.50 204.82 4.11

29.32 2.44 73.17 2.58 124.12 2.61 166.37 2.56 208.66 5.17

30.46 2.46 75.37 2.62 128.38 2.63 168.95 2.48 210.77 5.49

30.55 2.46 80.62 2.63 131.24 2.71 169.83 2.53 216.56 6.98

30.56 -- 85.00 2.61 135.49 2.59 172.43 2.38 220.67 --

39.84 2.48 92.61 2.56 138.47 2.53 177.74 2.39 228.02 --

Figure 95. Roberts Creek, beginning at mouth in Clayton County.

0.00 8.87 11.00 7.93 17.64 8.44 22.50 8.56 29.17 10.37

3.39 8.55 11.22 7.86 18.81 8.58 25.82 9.53 41.78 --

5.78 8.00 16.87 8.06 21.10 7.92 27.33 10.06 -- --

Figure 96. Rock River, beginning at mouth in Sioux County.

0.00 3.79 15.55 4.01 30.10 3.97 46.04 3.94 147.63 --

0.67 3.81 19.38 4.05 36.59 3.86 46.49 3.97 -- --

6.54 3.93 26.43 3.96 43.14 3.96 49.25 3.99 -- --

9.21 4.04 27.58 3.90 44.83 3.89 54.06 4.13 -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 41

Figure 97. Salt Creek, beginning at mouth in Benton County.

0.00 5.04 8.02 5.44 18.42 7.12 30.32 9.87 -- --

0.36 5.08 9.98 5.77 22.07 7.26 42.09 -- -- --

2.82 5.06 15.02 6.31 26.33 8.21 -- -- -- --

Figure 98. Sevenmile Creek, beginning at mouth in Montgomery County.

0.00 6.63 10.69 7.28 19.63 7.70 30.70 12.02 -- --

0.28 6.73 14.33 7.36 23.64 8.21 39.68 -- -- --

5.56 6.74 18.03 7.78 27.27 10.32 -- -- -- --

Figure 99. Shell Rock River, beginning at mouth in Black Hawk County.

0.00 3.13 11.66 3.24 37.43 3.41 54.59 3.41 131.15 --

1.15 3.15 20.24 3.30 38.20 3.44 59.97 3.09 -- --

3.88 3.22 22.57 3.29 40.85 3.64 61.99 3.06 -- --

8.04 3.25 29.51 3.41 43.45 3.57 65.90 2.83 -- --

10.73 3.21 36.80 3.39 50.64 3.40 69.46 -- -- --

Figure 100. Silver Creek, beginning at mouth in Mills County.

0.00 5.91 10.04 6.56 22.98 6.75 37.88 7.58 48.57 8.46

0.54 6.10 13.35 6.42 27.28 6.93 42.18 7.35 65.66 --

3.27 6.36 16.95 6.61 31.53 7.53 44.18 6.91 -- --

6.95 5.86 18.79 6.92 34.32 7.01 44.81 7.05 -- --

Figure 101. Sixmile Creek, beginning at mouth in Sioux County.

0.00 6.72 2.68 6.94 11.78 7.62 22.31 9.23 30.34 11.91

0.86 6.69 8.27 6.80 15.69 8.16 26.86 9.89 38.13 --

Figure 102. Skunk and South Skunk Rivers, beginning at mouth of Skunk River at Lee-Des Moines County line.

0.00 1.86 53.04 2.17 111.87 2.66 168.16 3.54 211.73 5.18

6.15 1.89 57.61 2.25 116.88 2.75 172.37 3.69 216.21 5.39

10.41 1.90 64.41 2.25 125.25 2.85 175.01 3.78 218.06 5.60

17.00 1.93 64.57 2.25 129.94 2.95 179.41 3.75 218.57 5.44

19.86 1.97 72.33 2.25 134.33 3.09 183.27 3.80 219.81 5.68

21.81 1.98 80.20 2.40 137.07 3.04 189.78 4.18 221.66 5.91

27.65 1.99 84.83 2.43 142.23 3.17 192.24 4.10 223.01 5.74

32.94 2.04 88.93 2.46 145.86 3.28 195.94 4.08 227.42 6.39

37.82 2.05 94.72 2.53 152.46 3.34 198.92 4.44 230.62 6.66

42.84 2.05 98.96 2.50 157.20 3.46 204.03 4.57 231.04 6.69

44.91 2.07 101.91 2.57 160.76 3.56 209.50 4.92 232.22 6.54

48.02 2.14 108.75 2.60 165.64 3.57 210.54 5.07 276.88 --

Figure 103. Soap Creek, beginning at mouth in Wapello County.

0.00 5.16 5.60 5.09 22.08 7.07 35.90 10.00 52.07 --

1.17 4.97 11.28 5.80 26.35 7.72 39.23 12.31 -- --

2.91 5.05 17.34 6.79 31.84 9.33 41.66 13.49 -- --

Figure 104. Soldier River, beginning at mouth in Harrison County.

0.00 5.73 12.33 6.54 26.29 7.80 41.17 9.50 53.32 12.78

3.04 5.96 13.97 6.64 27.35 7.68 44.68 9.55 57.99 15.12

3.77 6.03 15.23 6.76 32.97 8.34 48.12 11.75 67.22 --

8.72 6.23 20.71 7.23 37.48 9.14 49.14 11.31 -- --

Figure 105. South Beaver Creek, beginning at mouth in Butler County.

0.00 5.23 2.80 5.53 12.23 6.43 23.29 10.24 37.35 --

0.22 5.15 7.33 6.04 17.52 8.21 32.17 -- -- --

Figure 106. South English River, beginning at mouth in Washington County.

0.00 4.04 5.68 4.28 18.17 5.18 32.29 7.68 49.03 --

1.66 4.20 11.91 4.40 23.47 6.15 34.36 7.97 -- --

2.17 4.21 13.91 4.70 28.91 6.90 37.89 10.43 -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
42 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 107. South Fork Chariton River, beginning at Appanoose-Wayne County line.

0.00 4.45 6.86 5.79 14.14 6.06 21.22 6.60 33.93 --

3.60 4.77 12.15 5.80 17.56 5.83 24.31 7.10 -- --

Figure 108. South Fork Iowa River, beginning at mouth in Hardin County.

0.00 4.12 5.46 4.05 16.48 3.27 33.73 3.85 64.53 --

0.80 4.37 6.76 3.91 21.35 3.12 35.86 3.92 -- --

3.08 4.13 11.16 3.50 26.18 3.44 41.18 4.69 -- --

4.01 -- 12.82 3.23 31.56 3.85 41.59 -- -- --

Figure 109. South Raccoon River, beginning at mouth in Dallas County.

0.00 4.19 17.68 4.08 29.71 6.25 43.03 9.70 54.44 12.56

1.48 4.15 17.72 4.08 34.67 6.60 44.26 9.74 57.66 14.40

3.47 4.17 17.72 6.14 37.46 6.92 48.59 10.60 60.44 15.98

7.60 4.26 21.14 6.23 40.94 7.02 49.11 10.78 71.87 --

14.30 4.18 25.31 6.18 43.03 6.94 51.66 11.37 -- --

Figure 110. South River, beginning at mouth in Warren County.

0.00 5.14 9.55 6.03 22.88 6.55 39.88 8.28 52.54 15.37

2.83 5.48 13.68 6.18 24.79 6.42 40.04 8.22 62.04 --

2.90 -- 17.64 6.47 31.52 7.54 43.36 9.12 -- --

6.27 5.69 18.78 6.42 35.72 7.60 46.89 10.99 -- --

Figure 111. Squaw Creek, beginning at mouth in Story County.

0.00 5.75 2.47 6.04 10.52 6.34 18.39 5.82 23.89 5.81

0.82 5.84 7.65 6.23 14.79 6.15 18.57 -- 41.96 --

Figure 112. Squaw Creek, beginning at mouth in Warren County.

0.00 7.31 7.98 7.93 17.62 8.33 25.91 11.39 41.75 --

2.34 7.34 11.62 8.27 22.13 9.72 29.35 12.25 -- --

Figure 113. Sugar Creek, beginning at mouth in Muscatine County.

0.00 4.32 6.92 4.91 19.12 6.08 28.48 9.56 38.01 --

4.17 5.01 11.88 5.35 23.70 8.02 31.13 14.17 -- --

Figure 114. Sugar Creek, tributary to the Des Moines River, beginning at mouth in Lee County.

0.00 4.36 9.06 4.22 19.93 4.24 28.38 5.06 45.24 --

4.86 4.25 14.22 4.31 24.33 4.49 33.00 5.42 -- --

Figure 115. Sugar Creek, tributary to the Mississippi River, beginning at mouth in Lee County.

0.00 5.35 3.40 5.73 10.08 6.46 17.07 7.20 29.66 --

1.96 5.54 5.89 5.63 13.06 6.43 19.34 7.30 -- --

Figure 116. Tarkio River, beginning at Iowa-Missouri State line in Page County.

0.00 6.93 9.74 7.34 20.20 8.15 26.85 8.74 35.46 9.15

1.25 7.06 11.90 7.44 23.36 8.55 29.43 7.99 47.50 --

5.42 7.49 17.06 8.20 23.70 8.37 30.44 8.17 -- --

Figure 117. Thompson River, beginning at Iowa-Missouri State line in Decatur County.

0.00 2.96 26.28 3.17 55.43 3.75 83.28 5.01 105.94 13.47

5.76 3.01 32.58 3.26 58.59 3.79 85.86 5.57 115.72 --

10.43 3.04 37.32 3.29 64.24 3.73 92.83 6.22 -- --

13.40 2.95 44.37 3.50 69.82 4.28 96.83 7.90 -- --

20.76 3.04 48.74 3.72 76.22 4.61 98.21 8.67 -- --

23.62 3.18 49.33 3.76 79.97 -- 102.69 10.70 -- --

Figure 118. Timber and South Timber Creeks, beginning at mouth of Timber Creek in Marshall County.

0.00 6.06 3.77 7.02 12.32 9.83 24.01 -- -- --

3.59 6.92 7.36 7.40 15.97 13.25 -- -- -- --

Figure 119. Troublesome Creek, beginning at mouth in Cass County.

0.00 5.98 7.68 6.50 13.77 6.21 24.69 11.91 -- --

2.77 5.77 10.77 6.42 18.24 7.56 35.22 -- -- --

4.34 6.06 13.06 6.06 21.41 9.92 -- -- -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 43

Figure 120. Turkey Creek, beginning at mouth in Cass County.

0.00 7.33 4.22 8.03 10.83 8.44 15.46 10.36 21.93 11.92

0.19 7.18 6.15 8.25 12.72 8.63 19.32 10.62 32.93 --

Figure 121. Turkey River, beginning at mouth in Clayton County.

0.00 4.49 40.36 4.50 78.22 4.63 105.18 5.12 133.71 7.53

5.24 4.41 47.10 4.49 83.59 4.88 110.30 5.25 137.55 8.77

12.96 4.53 52.36 4.52 87.06 4.46 110.82 5.43 141.19 9.28

21.16 4.64 58.47 4.39 90.07 4.86 115.89 5.37 148.42 --

21.84 4.70 59.65 4.40 92.04 4.93 119.69 5.48 -- --

29.16 4.43 64.38 4.52 95.19 4.78 124.08 5.86 -- --

33.79 4.55 68.86 4.58 99.25 4.92 127.62 6.27 -- --

39.09 4.57 74.23 4.95 101.14 5.00 132.10 6.71 -- --

Figure 122. Upper Iowa River, beginning at mouth in Allamakee County.

0.00 4.98 24.37 5.07 52.49 4.80 83.40 4.46 115.20 4.61

3.25 4.96 31.27 4.96 56.98 4.84 87.32 4.69 119.42 4.48

5.44 4.99 36.58 4.85 59.11 4.87 91.52 4.30 122.54 5.28

8.61 5.01 37.68 4.85 63.16 4.77 94.10 4.11 127.42 5.81

12.01 4.98 38.57 4.85 67.68 4.65 98.61 4.18 130.89 6.40

14.98 4.89 44.02 4.87 73.88 4.82 104.55 4.04 134.57 6.72

18.28 5.02 48.53 4.84 78.99 4.39 109.18 4.11 154.73 --

Figure 123. Volga River, beginning at mouth in Clayton County.

0.00 6.69 19.18 6.98 35.85 7.60 55.87 6.91 64.76 8.00

0.52 6.75 27.52 7.37 38.42 7.44 56.33 6.77 69.98 9.58

9.33 6.86 27.78 7.40 42.04 7.03 56.77 6.63 81.12 --

14.67 6.97 34.93 7.51 45.92 7.46 61.11 7.40 -- --

Figure 124. Walnut Creek, beginning at mouth in Fremont County.

0.00 5.63 14.77 5.49 23.38 5.98 42.25 6.13 58.52 6.99

1.90 5.54 15.29 5.61 26.96 5.72 46.51 6.61 66.63 --

7.95 5.66 16.15 5.53 31.48 5.57 48.71 7.05 -- --

13.49 5.50 20.44 5.99 37.06 6.23 53.44 6.97 -- --

Figure 125. Walnut and Middle Walnut Creeks, beginning at mouth of Walnut Creek in Jefferson County.

0.00 5.82 5.85 6.74 11.23 8.88 15.84 12.29 27.26 --

Figure 126. Wapsinonoc and West Branch Wapsinonoc Creeks, beginning at mouth of Wapsinonoc Creek in Muscatine County.

0.00 3.79 7.84 4.48 15.99 5.37 23.00 10.98 -- --

3.98 4.37 13.66 5.32 19.75 7.02 31.72 -- -- -

Figure 127. Wapsipinicon River, beginning at mouth at Scott-Clinton County line.

0.00 2.26 69.12 2.34 132.32 2.53 189.44 3.04 254.11 4.19

3.59 2.21 73.30 2.35 134.64 2.55 193.57 3.10 257.23 4.26

10.34 2.25 79.34 2.33 144.48 2.61 199.66 3.19 260.74 4.27

18.19 2.20 89.95 2.46 149.46 2.66 204.59 3.29 264.22 4.70

20.57 2.18 92.68 2.41 155.19 2.75 207.95 3.28 267.79 4.90

29.17 2.23 92.88 2.40 157.30 2.71 213.80 3.37 273.51 5.52

34.60 2.22 94.95 2.42 157.99 2.70 216.92 3.42 278.98 6.14

38.41 2.26 98.88 2.34 158.30 2.70 223.77 3.41 284.30 7.01

45.01 2.23 100.02 2.35 164.79 2.78 225.13 3.47 288.03 9.46

54.28 2.25 101.61 2.36 169.57 2.80 228.24 3.48 297.48 --

56.79 2.27 110.83 2.54 173.90 2.88 232.60 3.65 -- --

58.14 2.30 115.10 2.49 179.58 2.94 236.95 3.74 -- --

60.76 2.26 118.68 2.46 183.76 2.99 242.19 3.72 -- --

65.19 2.33 123.58 2.60 184.50 2.96 247.90 3.69 -- --

Figure 128. Waterman Creek, beginning at mouth in O’Brien County.

0.00 7.29 5.51 6.57 18.27 5.70 25.90 6.63 33.52 8.72

0.75 7.36 11.77 6.17 22.03 6.01 30.49 7.05 43.98 --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
44 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood Frequency Discharges

Figure 129. Weldon River, beginning at Iowa-Missouri State line in Decatur County.

0.00 5.71 3.22 6.08 14.56 5.98 24.73 6.61 -- --

1.16 5.78 10.00 6.28 19.30 5.87 37.44 -- -- --

Figure 130. West Branch Floyd River, beginning at mouth in Plymouth County.

0.00 4.07 9.95 4.07 18.50 4.21 26.99 3.91 45.63 6.59

0.06 4.08 12.35 4.00 19.33 3.92 32.98 4.25 55.65 --

2.17 3.78 16.76 4.03 23.44 4.16 36.22 4.11 -- --

6.00 4.04 18.27 4.19 26.82 3.88 41.95 4.90 -- --

Figure 131. West Branch One Hundred and Two River, beginning at mouth in Taylor County.

0.00 5.63 7.55 5.77 15.53 7.49 30.01 -- -- --

0.94 5.51 10.17 6.02 19.86 7.78 -- -- -- --

Figure 132. West Fork Cedar River, beginning at mouth in Black Hawk County.

0.00 3.09 5.36 3.79 19.59 4.25 33.72 5.00 50.65 5.90

1.77 3.13 6.33 3.86 25.20 4.46 39.72 5.46 54.27 5.91

1.77 3.69 12.91 4.15 29.51 4.81 46.69 5.71 95.81 --

Figure 133. West Fork Ditch and West Fork Little Sioux River, beginning at Monona-Woodbury County line.

0.00 4.84 12.40 5.29 32.49 6.20 46.40 6.48 64.95 10.05

0.99 4.81 17.61 5.34 36.38 6.13 50.14 6.49 72.77 --

3.24 4.97 21.83 5.75 39.39 6.71 53.95 6.67 -- --

4.02 5.01 22.33 5.80 43.02 6.29 57.05 7.04 -- --

8.64 4.99 26.72 5.77 44.71 6.23 60.63 8.79 -- --

Figure 134. West Fork Middle Nodaway River, beginning at mouth in Adair County.

0.00 6.76 4.31 7.26 9.54 8.62 18.96 11.99 29.98 --

0.67 6.97 7.31 7.24 14.48 9.74 22.14 16.09 -- --

Figure 135. West Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor County.

0.00 5.22 6.76 5.89 15.04 5.75 26.10 7.23 -- --

3.22 5.39 9.83 5.58 20.61 6.45 39.06 -- -- --

Figure 136. West Fork West Nishnabotna River, beginning at mouth in Shelby County.

0.00 5.73 5.91 6.44 13.81 7.46 20.67 8.05 27.79 12.11

0.84 5.96 11.38 6.19 18.22 7.61 23.43 8.96 37.31 --

Figure 137. White Breast Creek, beginning at mouth in Marion County.

0.00 4.11 18.55 3.95 41.01 4.98 60.61 6.46 79.73 10.54

5.67 4.14 20.72 4.23 43.96 5.13 62.60 6.60 91.99 --

11.33 4.08 26.43 4.23 47.30 5.07 64.82 6.82 -- --

12.46 -- 31.72 4.50 49.68 5.24 69.09 7.68 -- --

16.08 3.82 36.60 4.89 56.49 6.09 74.05 8.25 -- --

Figure 138. Whitewater Creek, beginning at mouth in Jones County.

0.00 7.69 6.13 7.89 15.09 10.38 31.68 -- -- --

3.21 7.98 6.59 7.74 18.34 11.76 -- -- -- --

Figure 139. Willow Creek, beginning at mouth in Guthrie County.

0.00 3.26 5.56 3.86 10.81 5.88 18.50 12.33 28.74 --

1.38 3.46 7.64 4.67 15.61 8.31 21.07 14.94 -- --

Figure 140. Willow Creek, beginning at mouth in Harrison County.

0.00 8.25 7.70 9.33 17.65 10.07 32.94 12.98 -- --

0.16 8.28 11.82 9.87 23.69 11.40 36.58 14.67 -- --

2.35 8.59 13.42 9.54 28.04 13.12 46.54 -- -- --

Figure 141. Willow Creek, beginning at mouth in Plymouth County.

0.00 6.43 2.79 6.61 9.68 6.63 17.33 6.94 25.97 6.38

0.70 6.54 5.87 7.24 13.61 6.73 23.01 7.01 36.57 --

Figure 142. Winnebago River, beginning at mouth in Floyd County.

0.00 2.65 4.54 2.44 9.55 2.38 14.38 -- 20.21 2.07

1.32 2.56 7.00 2.49 13.61 2.32 17.81 2.18 105.82 --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
SUPPLEMENTAL DATA 45

Figure 143. Wolf Creek, beginning at mouth in Black Hawk County.

0.00 3.17 12.11 3.37 28.01 3.89 50.54 4.92 71.82 --

3.04 3.13 16.48 3.35 34.64 3.98 51.95 5.12 -- --

4.87 3.18 17.48 3.41 39.71 4.47 57.88 8.27 -- --

7.78 3.34 23.09 3.79 44.13 4.87 61.93 9.27 -- --

Figure 144. Yellow River, beginning at mouth in Allamakee County.

0.00 10.61 16.50 13.21 26.64 15.68 38.11 16.90 53.37 --

0.07 10.74 20.13 13.74 30.86 17.75 40.69 15.47 -- --

9.73 12.08 24.60 15.36 34.30 16.72 44.04 16.95 -- --

Table 9. River-mile and main-channel-slope values quantified for selected sites along selected streams in Iowa using a 

geographic information system technique and 1:24,000-scale topographic data and used to develop unadjusted mainchannel-slope curves for figures 7–144—Continued

[MCS, main-channel slope; ft/mi, feet per mile; -- , no data]

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)

River 

mile

MCS

(ft/mi)
46 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges
SUPPLEMENTAL DATA 47

List of sites used to quantify main-channel slopes of Bear Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 111 Mouth of Bear Creek 84N 1E 13 C --

1.06 -- State Highway 64 84N 1E 23 NE --

5.06 -- 33rd Street 84N 1E 27 SW 33rd St

6.65 70.9 50th Avenue 84N 1E 33 NW 50th Ave

10.30 61.3 4th Street (05417700, cont) 84N 1E 31 SE 4th St

12.94 57.9 Jackson-Jones County line 84N 1E 30 SW --

16.55 51.2 Bear Creek Road 84N 1W 26 SW Bear Creek Rd

23.33 -- State Highway 136, Wyoming 84N 1W 29 SW --

29.47 23.8 100th Avenue 84N 2W 27 NW 100th Ave

43.82 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Bear Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 7. Bear Creek, beginning at mouth in Jackson County.
48 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Bear and North Bear Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 118 Mouth of Bear Creek 99N 6W 1 NW --

0.48 118 State Highway 76 (05388320, low) 99N 6W 2 NE --

4.17 67.4 County Road A26 99N 6W 4 NE Bear Creek Dr

9.17 -- Willow Drive 100N 6W 32 N Willow Dr

11.60 55.4 Allamakee-Winneshiek County line 100N 6W 30 SW --

11.91 53.4 County Road A24 (05388300, low) 100N 7W 25 SE Quandahl Rd

14.98 28.5 North Bear Road 100N 7W 23 NW North Bear Rd

18.72 11.5 Iowa-Minnesota State line 100N 7W 11 N --

24.20 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 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

31

32

33

Bear Creek North Bear Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Bear and North Bear Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 8. Bear and North Bear Creeks, beginning at mouth of Bear Creek in Allamakee County.
SUPPLEMENTAL DATA 49

List of sites used to quantify main-channel slopes of Beaver Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 391 Mouth of Beaver Creek 90N 14W 34 SE --

1.55 -- County Road T75 90N 14W 28 SW Union Rd N

4.76 369 Black Hawk-Butler County line 90N 14W 31 NE --

9.87 347 County Road T55, New Hartford (05463000, cont) 90N 15W 28 SE Utica Ave

15.35 -- Ridge Avenue 90N 16W 25 SW Ridge Ave

18.39 314 County Road T47 90N 16W 27 NW Sinclair Ave

23.18 -- State Highway 14, Parkersburg 90N 16W 30 NW 6th St

24.57 145 Liberty Avenue (05462770, qw) 90N 17W 24 SW Liberty Ave

31.11 121 County Road T25, Aplington 90N 17W 20 SW 10th St

36.64 -- County Road T16, Austinville 90N 18W 22 C Dodge Ave

43.02 55.5 Butler-Franklin County line, County Road C65 

(05462700, low)

90N 18W 31 W Franklin Ave

45.52 -- County Road S56, Ackley 90N 19W 35 S Franklin St

48.70 -- Des Moines Lobe landform region boundary 90N 19W 28 SW --

48.71 -- Tulip Avenue 90N 19W 28 S Tulip Ave

53.67 27.5 County Road S55 90N 19W 31 SW Spruce Ave

65.04 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Beaver Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 9. Beaver Creek, beginning at mouth in Black Hawk County.
50 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Beaver Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 372 Mouth of Beaver Creek, Johnston 79N 24W 17 C --

1.80 -- State Highway 28, Johnston 79N 25W 13 NE Merle Hay Rd

6.26 358 NW 70th Avenue, Johnston (05481950, cont) 80N 25W 35 SW NW 70th Ave

12.96 -- State Highway 141 80N 25W 21 NW --

16.66 324 Polk-Dallas County line 80N 25W 18 SW --

19.25 314 County Road F31 (05481900, low) 80N 26W 2 SW 190th St

22.24 295 U Avenue 81N 26W 33 NW U Ave

25.20 -- Ranger Avenue (05481860, qw) 81N 27W 25 N Ranger Ave

31.75 -- State Highway 141 81N 27W 9 SW --

34.08 193 U.S. Highway 169 81N 27W 8 NW --

40.40 183 Dallas-Boone County line 81N 28W 3 NE --

47.18 175 305th Street (05481800, low) 82N 28W 15 W 305th St

50.90 -- County Road E57 82N 28W 3 NW 280th St

55.76 -- County Road P54 83N 28W 16 SW C Ave

59.04 84.5 230th Street (05481700, low) 83N 28W 6 S 230th St

59.75 -- Hydrologic Regions 1 and 2 boundary 83N 28W 6 SW --

60.47 38.5 U.S. Highway 30, Beaver (05481680, csg) 83N 28W 6 NE --

77.49 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Beaver Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 10. Beaver Creek, beginning at mouth in Polk County.
SUPPLEMENTAL DATA 51

List of sites used to quantify main-channel slopes of Big Bear Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 222 Mouth of Big Bear Creek 81N 11W 24 SW --

1.06 -- State Highway 212, Marengo 81N 11W 26 W --

2.25 -- U.S. Highway 6 81N 11W 35 NE --

3.45 -- 160th Street 80N 11W 3 NW 160th St

8.10 189 County Road V52, Ladora (05453000, cont) 80N 11W 7 SW G Ave

11.42 177 County Road V38 80N 12W 15 SW D Ave

14.99 167 Iowa-Poweshiek County line, State Highway 419 80N 12W 18 SW County Line

18.12 130 State Highway 21 80N 13W 15 SW --

22.57 77.9 County Road V18, Brooklyn (05452700, low) 80N 14W 14 NE Center St

24.54 -- U.S. Highway 6 80N 14W 15 NW --

28.87 48.7 120th Street 80N 15W 12 NW 120th St

30.98 -- U.S. Highway 63 80N 15W 3 SW --

34.55 -- 70th Street 81N 15W 31 SW 70th St

36.91 -- 50th Street 81N 16W 26 SW 50th St

45.54 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Big Bear Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 11. Big Bear Creek, beginning at mouth in Iowa County.
52 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Big Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 167 Mouth of Big Creek 70N 5W 19 SW --

1.84 164 310th Street (05473550, qw) 70N 5W 18 SW 310th St

6.80 140 285th Street (05473530, --) 70N 6W 2 SE 285th St

11.65 130 U.S. Highway 218 (05473520, --) 71N 6W 27 SW --

14.84 -- County Road H46 71N 6W 17 SE Oakland Mills Rd

19.60 -- U.S. Highway 34 71N 7W 7 W --

24.84 106 Hickory Avenue (05473500, cont) 72N 6W 29 NW Hickory Ave

27.37 58.0 Iowa Avenue (05473450, cont) 72N 6W 28 SE Iowa Ave

27.50 -- U.S. Highway 218 72N 6W 28 SE --

31.38 -- Kentucky Avenue 72N 6W 35 SW Kentucky Ave

34.91 37.4 Marsh Avenue 72N 5W 31 SW Marsh Ave

39.15 23.5 230th Street 71N 5W 9 NE 230th St

50.18 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Big Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 12. Big Creek, beginning at mouth in Henry County.
SUPPLEMENTAL DATA 53

List of sites used to quantify main-channel slopes of Big Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 111 Mouth of Big Creek 82N 6W 9 N --

1.11 -- U.S. Highway 151 and State Highway 13 82N 6W 4 NE --

3.13 81.2 Big Creek Road, Bertram (05464750, low) 83N 6W 34 NE Big Creek Rd

7.63 -- Red Haw Road 83N 6W 14 SE Red Haw Rd

10.72 -- County Road E45 83N 5W 6 SW Secrist Rd

14.95 -- U.S. Highway 151 84N 5W 30 SE --

21.71 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

9

10

11

12

13

14

15

16

17

18

19

20

21

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Big Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 13. Big Creek, beginning at mouth in Linn County.
54 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Big Muddy Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 103 Mouth of Big Muddy Creek 96N 36W 15 SW --

0.81 102 County Road B24 (06605300, low) 96N 36W 15 NW 350th St

3.19 66.6 340th Street 96N 36W 10 N 340th St

3.55 -- Des Moines Lobe landform region boundary 96N 36W 3 SE --

7.59 59.7 310th Street (06605200, low) 97N 36W 26 NW 310th St

11.46 -- 290th Street 97N 36W 13 NW 290th St

14.91 51.4 Clay-Dickinson County line, 270th Street 97N 35W 6 N 270th St

20.28 44.8 County Road A48 98N 35W 20 NW 240th St

23.44 27.2 County Road A34 98N 35W 9 NW 220th St

26.77 15.4 190th Street 99N 35W 27 NW 190th St

34.96 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Big Muddy Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 14. Big Muddy Creek, beginning at mouth in Clay County.
SUPPLEMENTAL DATA 55

List of sites used to quantify main-channel slopes of Black Hawk Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 344 Mouth of Black Hawk Creek, Waterloo 89N 13W 22 W --

0.57 -- U.S. Highway 218, Waterloo 89N 13W 22 SE Washington St

0.81 -- University Avenue, Waterloo 89N 13W 27 NE University Ave

5.90 -- U.S. Highway 20, Waterloo 88N 14W 1 SE --

6.41 327 Ranchero Road, Waterloo (05463510, qw) 88N 14W 12 NE Ranchero Rd

12.52 303 State Highway 58, Hudson (05463500, cont) 88N 14W 27 NE Hudson Rd

19.46 278 Black Hawk-Grundy County line, County Road T69 87N 14W 6 W Grundy Rd

23.16 145 242nd Street (05463320, --) 87N 15W 14 NE 242nd St

27.81 135 V Avenue, Reinbeck (05463300, low) 87N 15W 21 SW V Ave

33.75 82.0 R Avenue (05463110, --) 87N 16W 14 NW R Ave

36.82 71.0 P Avenue (05463100, low) 87N 16W 9 W P Ave

39.42 56.9 State Highway 14, Grundy Center (05463090, csg) 87N 16W 7 NW 4th St

45.90 -- County Road T29 87N 17W 10 NW K Ave

58.65 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Black Hawk Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 15. Black Hawk Creek, beginning at mouth in Black Hawk County.
56 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Boyer River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,188 Mouth of Boyer River 77N 44W 20 SE --

3.30 1,084 State Highway 362, Loveland (06609670, low) 77N 44W 4 C --

3.81 -- Pottawattamie-Harrison County line 77N 44W 4 N --

3.97 -- Interstate 29 78N 44W 33 SE --

5.23 935 Chicago Central and Pacific Railroad (06609550, low) 78N 44W 28 SE --

6.42 931 State Highway 183 78N 44W 22 SE --

11.14 -- 290th Street 78N 43W 6 C 290th St

15.70 871 U.S. Highway 30, Logan (06609500, cont) 79N 42W 19 NW --

18.93 -- Parker Trail 79N 42W 4 SW Parker Trl

23.56 811 U.S. Highway 30, Woodbine (06609480, --) 80N 42W 23 N --

27.80 -- 155th Street 81N 41W 31 C 155th St

30.02 732 U.S. Highway 30 (06609450, --) 81N 41W 20 SE --

34.03 -- State Highway 37, Dunlap 81N 41W 3 N --

34.31 678 Harrison-Crawford County line 82N 41W 34 SE --

40.33 -- Nelson Park Road 82N 40W 8 S Nelson Park Rd

43.26 -- U.S. Highway 30 82N 40W 3 SE --

48.44 -- U.S. Highway 30 83N 39W 20 S --

50.59 517 Lincoln Way (06609400, qw) 83N 39W 16 NE Lincoln Way

Figure 16. Boyer River, beginning at mouth in Pottawattamie County.

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110

3

4

5

6

7

8

9

10

11

12

13

14

15

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Boyer River

[See section "Presentation of Curves" for explanation of list elements]
SUPPLEMENTAL DATA 57

52.14 -- U.S. Highway 59, Denison 83N 39W 10 NE --

55.57 -- K Avenue 84N 39W 26 NE K Ave

58.32 290 County Road, Deloit (06609280, --) 84N 38W 7 SE County Road

62.28 -- F Avenue 85N 38W 33 NW F Ave

65.20 260 D Avenue (06609278, --) 85N 38W 23 NW D Ave

69.31 210 Crawford-Sac County line, A Avenue (06609275, --) 85N 37W 6 N A Ave

72.18 189 Karr Avenue 86N 37W 27 NW Karr Ave

75.28 -- County Road D59 86N 37W 14 NW 360th St

79.88 132 U.S. Highway 71 (06609265, --) 87N 37W 34 NE --

84.42 -- U.S. Highway 71 87N 37W 10 W --

88.76 99.0 County Road D37 88N 37W 33 N 270th St

94.62 -- 240th Street 88N 37W 16 NE 240th St

100.01 67.5 U.S. Highway 20 (06609260, low) 88N 37W 6 NE --

105.50 -- County Road D15 89N 37W 22 N 190th St

109.28 19.5 County Road M43 89N 37W 4 SW Gard Ave

118.19 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Boyer River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 16. Boyer River, beginning at mouth in Pottawattamie County—Continued
58 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Brushy Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 142 Mouth of Brushy Creek 79N 31W 22 NE --

0.98 142 245th Street (05483330, low) 79N 31W 15 C 245th St

3.47 -- State Highway 44 79N 31W 4 SE --

7.65 -- State Highway 25 80N 31W 19 NE --

11.68 116 County Road N70 80N 32W 10 N Justice Rd

18.01 102 County Road F24 81N 33W 35 NW 150th Rd

21.44 95.5 County Road N46 81N 33W 21 NW Chestnut Rd

24.95 -- Guthrie-Audubon County line, Swift Avenue 81N 34W 1 NE Swift Ave

25.47 83.1 Audubon-Carroll County line 82N 34W 36 SE --

26.93 -- State Highway 141 82N 34W 35 NE --

28.72 68.1 320th Street (05483320, low) 82N 34W 22 SE 320th St

33.34 51.8 County Road E57 82N 34W 7 NW 290th St

35.34 45.0 U.S. Highway 71 (05483318, csg) 82N 35W 1 NW --

40.22 24.1 County Road N18 83N 35W 21 NW Ivy Ave

51.01 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Brushy Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 17. Brushy Creek, beginning at mouth in Guthrie County.
SUPPLEMENTAL DATA 59

List of sites used to quantify main-channel slopes of Buffalo and East Branch Buffalo Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 232 Mouth of Buffalo Creek, Anamosa 84N 4W 10 NW --

0.43 231 County Road E28, Anamosa (05421720, --) 84N 4W 3 SW Cherry St

5.19 217 Freemont Road (05421700, low) 85N 4W 30 SE Freemont Rd

8.29 203 Jones-Linn County line 85N 4W 19 NW --

13.30 189 County Road X20 (05421682, --) 85N 5W 3 SW Prairieburg Rd

15.01 185 County Road E16 (05421680, --) 85N 5W 5 NE Sawyer Rd

20.08 -- Red Bridge Road 86N 5W 19 NW Red Bridge Rd

24.46 -- State Highway 13, Coggon 86N 6W 10 NE --

26.83 142 Linn-Delaware County line 86N 6W 4 NE Linn-Delaware Rd

28.88 138 120th Avenue (05421660, --) 87N 6W 28 SW 120th Ave

32.72 -- Delaware-Buchanan County line 87N 6W 18 SW --

36.69 103 County Road D47 (05421630, --) 87N 7W 2 SE 285th St

42.87 -- 250th Street 88N 7W 21 NE 250th St

47.69 -- U.S. Highway 20 88N 7W 6 SW --

48.69 71.4 State Highway 939, Winthrop (05421600, csg) 88N 8W 1 NE --

51.52 68.2 County Road W45 (05421550, csg) 89N 8W 25 NE Slater Ave

54.42 -- 180th Street 89N 8W 12 SE 180th St

61.71 -- 150th Street 90N 7W 31 NW 150th St

78.54 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Buffalo Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

East Branch Buffalo Creek

List of sites used to quantify main-channel slopes of Buffalo and East Branch Buffalo Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 18. Buffalo and East Branch Buffalo Creeks, beginning at mouth of Buffalo Creek in Jones County.
60 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Buttrick Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 218 Mouth of Buttrick Creek 83N 30W 26 SE --

3.36 215 250th Street (05483210, qw) 83N 30W 24 N 250th St

8.75 202 U.S. Highway 30 (05483200, low) 84N 30W 36 SE --

10.22 -- Hydrologic Regions 1 and 2 boundary 84N 30W 25 SE --

10.26 196 Confluence of East and West Buttrick Creeks 84N 30W 25 SE --

50.15 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Buttrick Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 19. Buttrick Creek, beginning at mouth in Greene County.
SUPPLEMENTAL DATA 61

List of sites used to quantify main-channel slopes of Cedar Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address "911" 

street name

0.00 565 Mouth of Cedar Creek 71N 7W 9 NW --

4.43 530 County Road H46 (05473400, cont) 71N 7W 28 NW 260th St

10.16 512 County Road J6W 70N 7W 9 SW Agency Rd

15.19 440 Henry-Van Buren County line 70N 7W 7 SW --

20.65 435 County Road W40 70N 8W 2 S Willow Rd

27.24 -- Van Buren-Jefferson County line 70N 8W 5 NE --

33.13 -- County Road W30 71N 9W 36 NW Stockport Rd

37.30 381 Osage Avenue 71N 9W 28 S Osage Ave

40.76 344 State Highway 1 (05473320, --) 71N 10W 13 SW --

44.59 323 County Road H43 71N 10W 3 SW Libertyville Rd

50.05 284 Fir Avenue 72N 11W 36 NW Fir Ave

52.65 252 U.S. Highway 34 (05473300, csg) 72N 11W 27 SW --

56.96 165 Jefferson-Wapello County line 72N 11W 18 SW --

60.06 -- County Road V43 72N 12W 3 S Competine Rd

64.21 -- County Road V37 73N 12W 31 NW Agency Hedrick Rd

68.49 73.6 County Road V5H (05473200, low) 73N 13W 21 SW Highland Center Rd

72.72 50.5 State Highway 149 73N 13W 7 NW --

75.35 40.4 Wapello-Mahaska County line 73N 14W 3 NE --

77.80 26.4 Trenton Avenue 74N 14W 28 SW Trenton Ave

86.93 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

2

3

4

5

6

7

8

9

10

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Cedar Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 20. Cedar Creek, beginning at mouth in Henry County.
62 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Cedar Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 423 Mouth of Cedar Creek 75N 17W 33 NE --

2.66 -- Ashland Avenue (05489030, qw) 75N 17W 31 NE Ashland Ave

3.19 419 Mahaska-Marion County line 75N 17W 31 W --

8.80 374 State Highway 156 (05489000, cont) 74N 18W 11 SW --

13.35 241 State Highway 5 (05488750, qw) 74N 18W 28 NE --

18.17 232 Marion-Monroe County line, Wyoming Street 74N 18W 31 SW Wyoming St

23.22 211 130th Street (05488700, qw) 73N 18W 16 SW 130th St

29.31 137 602nd Avenue 72N 18W 2 NW 602nd Ave

34.20 127 188th Trail 72N 17N 18 SW 188th Trl

37.60 102 U.S. Highway 34 (05488600, qw) 72N 18W 26 NE --

42.45 73.6 227th Street 71N 18W 4 SW 227th St

45.64 -- County Road T13 71N 18W 6 SE 560th Ave

51.64 23.9 County Road S70, Melrose (05488550, low) 71N 19W 4 SE 520th Ave

63.75 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

4

5

6

7

8

9

10

11

12

13

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Cedar Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 21. Cedar Creek, beginning at mouth in Mahaska County.
SUPPLEMENTAL DATA 63

List of sites used to quantify main-channel slopes of the Cedar River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 5,814 Buchanan-Black Hawk County line 87N 11W 36 SE --

6.65 5,360 Brandon Road (05464090, --) 87N 11W 19 NE Brandon Rd

14.72 5,240 County Road D38, Gilbertville (05464020, qw) 88N 12W 23 SW Washburn Rd E

21.72 -- Interstate 380, Waterloo 88N 13W 12 NE --

26.28 5,146 USGS gage at end of East Seventh Street, Waterloo 

(05464000, cont)

89N 13W 25 NW --

26.84 -- U.S. Highway 63, Waterloo 89N 13W 23 SE E Mullan Ave

30.60 -- U.S. Highway 218, Waterloo 89N 13W 16 SW Washington St

33.35 -- State Highway 58, Cedar Falls 89N 13W 18 NW --

34.26 -- State Highway 57, Cedar Falls 89N 14W 12 NE 1st St

34.69 4,734 Franklin Street, Cedar Falls (05463050, qw) 89N 14W 12 NW Franklin St

42.75 4,315 County Road C57 90N 14W 15 NW Cedar-Wapsi Rd W

46.07 -- Black Hawk-Bremer County line, Janesville 90N 14W 2 N 7th St (Old IA 969)

46.59 1,661 USGS gage at end of East Barrick Road, Janesville 

(05458500, cont)

91N 14W 35 SW --

46.88 -- U.S. Highway 218 91N 14W 35 NW --

57.42 1,549 State Highway 3, Waverly 91N 14W 2 NW Bremer Ave

DISTANCE UPSTREAM FROM BUCHANAN-BLACK HAWK COUNTY LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Cedar River

[See section "Presentation of Curves" for explanation of list elements]

Figure 22. Cedar River, beginning at Buchanan-Black Hawk County line.
64 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

58.88 1,547 County Road V14, Waverly (05458300, cont) 92N 14W 35 SW Horton Rd

63.67 1,534 County Road C33 92N 14W 21 NW 190th St

70.61 -- State Highway 188, Plainfield 93N 14W 29 NE --

77.20 1,443 Bremer-Chickasaw County line 93N 14W 5 NW --

82.08 1,113 State Highway 346, Nashua (05457770, --) 94N 14W 18 SE Veterans Dr

83.79 1,080 Chickasaw-Floyd County line 94N 14W 7 NW --

87.51 1,075 Ripley Bridge Drive, Midway (05457750, qw) 95N 15W 34 NE Ripley Bridge Dr

95.24 1,054 U.S. Highway 18, Charles City (05457700, cont) 95N 16W 12 NE Brantingham St

105.08 990 U.S. Highway 218, Floyd (05457650, qw) 96N 16W 16 SE Monroe St

113.73 -- 105th Street 97N 17W 24 NE 105th St

114.97 888 Floyd-Mitchell County line 97N 17W 24 NW --

118.24 -- County Road T38 97N 17W 2 NE Lancer Ave

122.99 831 State Highway 9 98N 17W 28 NE --

126.64 826 County Road A43, Mitchell (05457500, cont) 98N 17W 8 SE Hickory Ave

131.56 813 County Road T26 99N 18W 36 NW Foothill Ave

132.95 804 County Road A38, St. Ansgar (05457470, --) 99N 18W 26 N 420th St

134.36 -- County Road 99N 18W 14 SW Hwy 105

141.02 656 County Road A19, Otranto (05457350, low) 100N 18W 28 NW 480th St

145.25 584 Iowa-Minnesota State line 100N 18W 8 NW State Line St

201.68 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Cedar River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 22. Cedar River, beginning at Buchanan-Black Hawk County line—Continued.
SUPPLEMENTAL DATA 65

List of sites used to quantify main-channel slopes of the Chariton River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Wayne-Lucas County line 71N 20W 36 SE --

7.63 -- County Road S56 71N 20W 33 SW --

12.19 -- County Road S50 71N 20W 19 SW --

17.83 182 County Road S43 (06903400, cont) 71N 21W 15 NE --

23.98 104 State Highway 14 (06903340, qw) 72N 21W 32 SW --

30.59 92.9 County Road 71N 22W 2 N --

35.25 82.6 County Road S23 71N 22W 15 NW --

39.06 -- County Road 71N 22W 17 NW --

43.64 71.0 Abandoned County Road bridge (06903300, low) 71N 23W 13 NW --

44.80 -- U.S. Highway 65 (06903290, --) 71N 23W 11 NE --

49.54 -- County Road H50 71N 23W 17 NW --

54.79 -- Lucas-Clarke County line 71N 23W 19 SW --

55.00 -- Church Street (06903200, qw) 71N 24W 25 NE Church St

55.48 -- Clarke-Lucas County line 71N 23W 30 NW --

58.45 22.0 Lucas-Wayne County line, Watrous Street 70N 23W 6 NE Watrous St

66.74 -- Drainage divide -- --

DISTANCE UPSTREAM FROM WAYNE-LUCAS COUNTY LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Chariton River

[See section "Presentation of Curves" for explanation of list elements]

Figure 23. Chariton River, beginning at Wayne-Lucas County line.
66 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Chequest Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 125 Mouth of Chequest Creek 69N 10W 27 NE --

3.20 123 Ivy Trail (05490400, low) 69N 10W 21 S Ivy Trl

11.06 108 County Road V64 69N 11W 14 S Rte V64

17.34 95.1 205th Road 69N 11W 20 NE 205th Rd

20.91 85.5 Van Buren-Davis County line 69N 11W 7 SW --

21.18 85.0 Yoke Boulevard (05490300, low) 69N 12W 12 SE Yoke Blvd

27.78 41.0 County Road V42 70N 12W 33 NW 160th St

33.88 -- Quince Boulevard 70N 13W 35 N Quince Blvd

48.96 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Chequest Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 24. Chequest Creek, beginning at mouth in Van Buren County.
SUPPLEMENTAL DATA 67

List of sites used to quantify main-channel slopes of Clanton and North Fork Clanton Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 160 Mouth of Clanton Creek 76N 25W 28 N --

1.37 159 28th Avenue (05486350, low) 76N 25W 32 NE 28th Ave

3.31 -- Interstate 35 75N 25W 6 C --

4.11 151 Warren-Madison County line 75N 25W 7 NW --

10.15 -- County Road G50 75N 26W 22 NW Saint Charles Rd

15.97 -- Settlers Trail 75N 26W 32 C Settlers Trl

20.57 84.5 County Road G68, East Peru (05486300, low) 74N 27W 11 NE Emerson St

24.32 -- Clanton Creek Trail 74N 27W 15 NW Clanton Creek Trl

29.88 29.5 County Road P71 74N 28W 12 NE Clark Tower Rd

32.35 -- U.S. Highway 169 74N 28W 2 S --

45.57 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Clanton Creek North Fork Clanton Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Clanton and North Fork Clanton Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 25. Clanton and North Fork Clanton Creeks, beginning at mouth of Clanton Creek in Warren 

County.
68 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Clear Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 105 Mouth of Clear Creek, Coralville 79N 6W 8 NE --

0.44 -- U.S. Highway 6, Coralville 79N 6W 8 NW 2nd St

2.79 98.1 Camp Cardinal Road (05454300, cont) 79N 7W 1 SE 22nd Ave

4.80 84.5 340th Street (05454280, --) 80N 7W 36 SW 340th St

5.79 -- Interstate 80 80N 7W 35 NW --

6.50 -- Interstate 380 80N 7W 34 NE --

10.27 74.1 Copi Road 80N 7W 30 SE Copi Rd

13.48 58.4 Echo Avenue (05454220, cont) 80N 8W 23 SE Echo Ave

16.10 55.0 County Road W38, Oxford (05454200, low) 80N 8W 28 NE Chambers Ave

20.00 41.1 Johnson-Iowa County line 80N 8W 30 NW Johnson Iowa Rd

22.41 24.5 W Avenue 80N 9W 26 W W Ave

30.60 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

5

6

7

8

9

10

11

12

13

14

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Clear Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 26. Clear Creek, beginning at mouth in Johnson County.
SUPPLEMENTAL DATA 69

List of sites used to quantify main-channel slopes of Crane Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 109 Mouth of Crane Creek 90N 11W 26 SW --

0.24 109 Wheeler Road (05420830, --) 90N 11W 27 SE Wheeler Rd

3.23 -- State Highway 281, Dunkerton 90N 11W 29 SE Canfield Rd

5.04 101 Pilot Grove Road North (05420820, low) 90N 11W 29 SW Pilot Grove Rd N

10.32 81.3 Bennington Road East 90N 12W 23 NW Bennington Rd E

14.61 63.6 Black Hawk-Bremer County line, Marquis Road 

(05420800, low)

90N 12W 3 NW Marquis Rd E

17.53 -- County Road C50 91N 12W 28 NW 260th St

21.46 45.5 State Highway 3 (05420780, --) 91N 12W 9 NW --

27.63 -- County Road C33 92N 12W 20 NW 190th St

39.81 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Crane Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 27. Crane Creek, beginning at mouth in Black Hawk County.
SUPPLEMENTAL DATA 70

List of sites used to quantify main-channel slopes of Crane Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 214 Mouth of Crane Creek 95N 9W 31 NW --

4.31 -- U Avenue 95N 10W 34 SE U Ave

7.29 176 State Highway 193 94N 10W 4 NE --

11.04 148 Fayette-Chickasaw County line 95N 10W 30 NW --

13.44 -- Windsor Road 95N 11W 24 NE Windsor Rd

17.63 135 State Highway 24, Lawler 95N 11W 4 SE South St

20.63 128 180th Street 96N 11W 32 NW 180th St

23.20 119 160th Street 96N 11W 19 NW 160th St

27.78 108 Pembroke Road 96N 12W 11 NW Pembroke Rd

31.71 97.7 County Road B22, Jerico 97N 12W 33 NE 120th St

35.43 90.5 Chickasaw-Howard County line, County Road B16 97N 12W 21 NW 100th St

39.47 -- State Highway 63 97N 12W 8 NW --

40.72 75.8 County Road B17 (05411700, csg) 97N 12W 6 NW 185th St

46.13 59.5 155th Street 98N 13W 23 E 155th St

50.10 41.1 135th Street 98N 13W 10 C 135th St

51.81 -- 125th Street 98N 13W 4 E 125th St

56.04 17.4 State Highway 9, Saratoga 99N 13W 29 NE --

65.66 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60

4

5

6

7

8

9

10

11

12

13

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Crane Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 28. Crane Creek, beginning at mouth in Fayette County.
SUPPLEMENTAL DATA 71

List of sites used to quantify main-channel slopes of Crooked and West Fork Crooked Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 286 Mouth of Crooked Creek 73N 8W 1 NE --

0.56 284 State Highway 78, Coppock (05473060, qw) 73N 7W 6 NW --

1.06 -- Henry-Washington County line 73N 7W 6 NE --

3.47 259 320th Street (05473050, low) 74N 7W 30 NE 320th St

9.13 -- County Road W55 74N 7W 16 SE Wayland Rd

15.17 -- Sockum Ridge Road 74N 7W 13 NE Sockum Ridge Rd

20.37 -- County Road W55 74N 7W 5 NE Wayland Rd

26.52 94.1 State Highyway 1 75N 8W 24 SE --

35.05 69.0 State Highway 92 75N 8W 3 N --

41.24 -- County Road W38 76N 8W 30 W Ginkgo Ave

46.50 -- Dogwood Avenue 76N 9W 27 NW Dogwood Ave

51.06 19.1 Washington-Keokuk County line, County Road V15 76N 9W 19 SW Keokuk 

Washington Rd

59.48 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Crooked Creek West Fork Crooked Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Crooked and West Fork Crooked Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 29. Crooked and West Fork Crooked Creeks, beginning at mouth of Crooked Creek in Jefferson 

County.
72 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Deep Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 143 Mouth of Deep Creek 84N 5E 18 C --

2.59 -- State Highway 64 84N 5E 30 W --

3.12 91.9 17th Street (05418700, low) 84N 5E 31 NW 17th St

4.62 88.3 Jackson-Clinton County line 84N 5E 31 SE --

7.99 67.7 125th Street (05418650, low) 83N 5E 17 C 125th St

14.22 41.9 State Highway 136, Charlotte 83N 4E 27 SE --

18.28 29.6 290th Avenue 83N 4E 32 NE 290th Ave

31.07 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Deep Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 30. Deep Creek, beginning at mouth in Jackson County.
SUPPLEMENTAL DATA 73

List of sites used to quantify main-channel slopes of the East Boyer River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 131 Mouth of East Boyer River, Denison 83N 39W 10 SE --

0.34 130 U.S. Highway 30, Denison (06609350, low) 83N 39W 10 SE --

2.13 127 County Road M36, Denison (06609345, --) 83N 39W 13 N Donna Reed Rd

6.21 -- County Road M38 83N 38W 3 W 310th St

10.62 65.4 County Road M55, Vail (06609300, low) 84N 37W 30 C County Rd

13.27 -- U.S. Highway 30 84N 37W 21 NE --

23.06 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Boyer River

[See section "Presentation of Curves" for explanation of list elements]

Figure 31. East Boyer River, beginning at mouth in Crawford County.
74 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the East Branch West Nishnabotna River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 227 Mouth of East Branch West Nishnabotna River 77N 39W 29 NW --

1.71 -- U.S. Highway 59 77N 39W 21 N --

3.00 223 State Highway 83, Avoca (06807400, low) 77N 39W 16 NE --

5.21 -- Interstate 80 77N 39W 3 E --

5.75 204 Pottawattamie-Shelby County Line 77N 39W 3 NE --

10.28 183 450th Street (06807390, --) 78N 39W 13 W 450th St

13.48 -- Quince Road 78N 39W 5 SW Quince Rd

17.98 151 State Highway 44 (06807380, low) 79N 38W 23 NE --

21.06 -- County Road M47 79N 37W 6 NW Road M47

24.71 -- County Road M56 80N 37W 27 NW Road M56

28.59 70.3 Shelby-Audubon County line, Yellowwood Road 

(06807360, low)

80N 37W 13 NE Yellowwood Rd

32.36 -- Dove Avenue 80N 36W 3 E Dove Ave

37.11 17.2 Goldfinch Avenue 81N 35W 19 NW Goldfinch Ave

42.90 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

6

8

10

12

14

16

18

20

22

24

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Branch West Nishnabotna River

[See section "Presentation of Curves" for explanation of list elements]

Figure 32. East Branch West Nishnabotna River, beginning at mouth in Pottawattamie County.
SUPPLEMENTAL DATA 75

List of sites used to quantify main-channel slopes of East Fork Crooked Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 122 Mouth of East Fork Crooked Creek 74N 7W 24 NE --

3.31 -- 320th Street 74N 6W 29 N 320th St

7.86 -- U.S. Highway 218 74N 6W 27 SW --

12.75 -- Washington-Henry County line 74N 6W 36 S --

18.86 65.3 County Road W66 (05473020, low) 73N 5W 9 NE Oasis Ave

22.93 -- 130th Street, Winfield 73N 5W 22 NW 130th St

27.04 -- State Highway 78 73N 5W 36 NW --

35.21 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

2

3

4

5

6

7

8

9

10

11

12

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of East Fork Crooked Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 33. East Fork Crooked Creek, beginning at mouth in Washington County.
76 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the East Fork One Hundred and Two River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 111 Iowa-Missouri State line 67N 34W 31 NW --

4.41 -- 308th Way 67N 34W 17 SE 308th Way

6.51 92.1 County Road J55 (06819190, cont) 67N 34W 9 NE 290th St

9.13 85.4 County Road N44, Bedford (06819185, cont) 68N 34W 35 NE Linwood Ave

10.30 -- State Highway 2 68N 34W 25 NW --

14.99 60.4 220th Street (06819180, low) 68N 33W 4 NW 220th St

17.69 -- County Road J35, Conway 69N 33W 26 NW 200th St

22.11 -- State Highway 49 69N 33W 12 N --

34.35 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Fork One Hundred and Two River

[See section "Presentation of Curves" for explanation of list elements]

Figure 34. East Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor County.
SUPPLEMENTAL DATA 77

List of sites used to quantify main-channel slopes of the East Fork Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 148 Mouth of East Fork Wapsipinicon River 93N 12W 34 SE --

2.67 144 State Highway 93 (05420720, low) 93N 12W 26 NW --

8.83 123 Bremer-Chickasaw County line (05420710, --) 93N 12W 3 NW 310th St

13.37 97.1 280th Street 94N 12W 22NW 280th St

17.76 83.5 U.S. Highway 18, Fredericksburg (05420705, --) 94N 12W 13 NW --

22.59 62.2 County Road B54 (05420700, low) 95N 12W 36 NW 240th St

29.76 -- State Highway 24 95N 12W 9 NW --

33.63 30.3 U.S. Highway 63 (05420690, csg) 96N 12W 31 SE --

37.28 21.8 County Road B33 96N 13W 25 NW 170th St

50.55 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Fork Wapsipinicon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 35. East Fork Wapsipinicon River, beginning at mouth in Bremer County.
78 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the East Nishnabotna River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,148 Mouth of East Nishnabotna River 67N 42W 2 NE --

3.55 1,106 County Road J46, Riverton (06809900, --) 68N 41W 29 NW 250th St

4.69 -- County Road L68, Riverton 68N 41W 20 NE 330th Ave

10.67 1,082 County Road M16 (06809800, low) 69N 40W 30 SE 370th Ave

12.53 -- State Highway 2 69N 40W 28 SE --

17.04 1,019 Fremont-Page County line, U.S. Highway 59 (06809750, 

--)

69N 40W 13 NE --

22.35 -- 150th Street, Essex 70N 39W 27 SW 150th St

28.12 953 Page-Montgomery County line 70N 39W 1 NW --

31.95 -- County Road H46 71N 38W 19 NW 250th St

38.14 894 Coolbaugh Street, Red Oak (06809500, cont) 72N 38W 29 SE 205th St

39.35 -- U.S. Highway 34, Red Oak 72N 38W 20 NW --

41.83 888 State Highway 48 72N 38W 8 SE --

46.27 -- County Road H20, Stennett 73N 38W 34 N 150th St

51.34 -- State Highway 48, Elliott 73N 38W 11 NE --

52.31 837 Montgomery-Pottawattamie County line 73N 38W 1 NW --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120

4

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Nishnabotna River

[See section "Presentation of Curves" for explanation of list elements]

Figure 36. East Nishnabotna River, beginning at mouth in Fremont County.
SUPPLEMENTAL DATA 79

57.86 -- State Highway 92 74N 38W 1 SE --

59.66 789 Pottawattamie-Cass County line 75N 38W 36 NE --

62.37 778 State Highway 48 (06809450, low) 75N 37W 19 NE --

66.87 574 U.S. Highway 6 (06809330, low) 75N 37W 10 NE --

69.24 436 Lansing Road (06809210, cont) 76N 37W 35 NW Lansing Rd

74.33 382 County Road G30, Atlantic (06809200, low) 76N 36W 6 SE 6th St

74.64 -- State Highway 83, Atlantic 76N 36W 6 SE 2nd St

78.33 -- Great River Road 77N 36W 27 SW Great River Rd

81.48 237 U.S. Highways 6 and 71 77N 36W 14 SE --

83.99 -- Interstate 80 77N 36W 1 SE --

84.54 224 Cass-Audubon County line 77N 36W 1 NE --

87.69 -- 320th Street, Brayton 78N 35W 19 NE 320th St

91.35 -- U.S. Highway 71, Exira 78N 35W 4 SW --

91.61 195 County Road F58, Exira (06808900, low) 78N 35W 4 NW Littlefield Dr

96.40 -- U.S. Highway 71 79N 35W 15 NE --

97.51 -- State Highway 44 79N 35W 11 SW --

102.32 -- County Road F32 80N 35W 23 NE 190th St

105.83 66.7 Mockingbird Avenue (06808850, low) 80N 34W 6 NW Mockingbird Ave

110.31 -- 130th Street 81N 34W 19 NE 130th St

115.24 15.2 Audubon-Carroll County line 81N 35W 3 NW --

122.68 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the East Nishnabotna River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 36. East Nishnabotna River, beginning at mouth in Fremont County—Continued.
80 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the East Nodaway River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 334 Mouth of East Nodaway River 67N 36W 7 N --

0.67 333 County Road J53 (06817100, low) 67N 36W 6 SE Teak Ave

2.71 -- 260th Street 68N 36W 33 NW 260th St

7.16 -- State Highway 2 68N 36W 4 N --

12.40 299 County Road J31 69N 36W 13 C Willow Ave

14.51 291 Page-Taylor County line 69N 36W 1 SE Taylor-Page Road

18.79 -- County Road J20 70N 35W 20 NW 130th St

21.91 251 Taylor-Adams County line 70N 35W 6 NE Adams-Taylor Rd

26.28 242 County Road N26, Nodaway 71N 35W 17 SE Birch Ave

30.49 -- Fig Avenue 71N 35W 12 N Fig Ave

36.79 -- U.S. Highway 34 71N 34W 3 NW --

37.73 165 State Highway 148, Corning 71N 34W 2 NW Quincy Ave

41.13 -- Mulberry Avenue 72N 33W 30N Mulberry Ave

46.56 -- County Road N61, Prescott 72N 33W 23 SE Quince Ave

53.48 -- Tulip Avenue 72N 32W 9 NW Tulip Ave

60.14 54.2 140th Avenue (06817050, low) 73N 32W 28 NW 140th Ave

75.06 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the East Nodaway River

[See section "Presentation of Curves" for explanation of list elements]

Figure 37. East Nodaway River, beginning at mouth in Page County.
SUPPLEMENTAL DATA 81

List of sites used to quantify main-channel slopes of English Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 112 Mouth of English Creek 75N 18W 3 SW --

2.27 108 County Road T17 (05488300, low) 75N 18W 5 E Hwy T17

8.54 -- Old Highway 92 75N 19W 11 NW Old Hwy 92

12.73 90.1 State Highway 92 (05488200, cont) 75N 19W 16 SE --

15.10 -- State Highway 5 75N 19W 21 NW --

19.43 73.0 135th Place 75N 19W 30 C 135th Pl

21.22 -- State Highway 14 75N 20W 24 S --

28.32 57.4 County Road G62 74N 20W 4 NE Quebec St

31.18 46.3 County Road G76 74N 20W 16 C Hwy G76

34.39 -- 78th Avenue (05488180, qw) 74N 20W 30 SE 78th Ave

46.68 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of English Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 38. English Creek, beginning at mouth in Marion County.
82 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the English and North English Rivers—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 638 Mouth of English River 77N 6W 11 SE --

3.18 -- State Highway 923 77N 6W 15 NW --

3.87 -- U.S. Highway 218 77N 6W 16 N --

6.66 626 County Road W61, Riverside 77N 6W 17 SW Riverside Road

15.44 599 Nutmeg Avenue 77N 7W 17 SW Nutmeg Ave

17.03 573 State Highway 1, Kalona (05455500, cont) 77N 8W 13 SE --

21.93 -- State Highway 22 77N 8W 10 SE --

25.05 472 Hickory Avenue (05455470, --) 77N 8W 8 SW Hickory Ave

28.35 -- County Road W38 77N 8W 7 SW Ginkgo Ave

33.61 455 County Road W21 77N 9W 3 SW Dogwood Ave

36.60 449 Between dead-end roads, Birch Avenue (05455455, --) 77N 9W 5 SE Birch Ave

38.09 -- Washington-Iowa County line 77N 9W 6 N --

38.85 310 County Road W18 (05455272, --) 78N 9W 31 SW S Ave

41.51 302 County Road F67 (05455270, qw) 78N 10W 27 SE PP Ave

43.08 296 Abandoned bridge, OO Avenue (05455265, --) 78N 10W 28 C OO Ave

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

3

4

5

6

7

8

9

10

11

English River North English River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the English and North English Rivers

[See section "Presentation of Curves" for explanation of list elements]

Figure 39. English and North English Rivers, beginning at mouth of English River 

in Washington County.
SUPPLEMENTAL DATA 83

45.04 221 310th Street (05455250, low) 78N 10W 17 SW 310th St

46.80 215 State Highway 149 78N 10W 7 SW --

48.44 210 County Road F52 (05455248, --) 78N 11W 1 SW F52 Trl

52.25 178 County Road V52 (05455244, --) 79N 11W 32 SE H Ave

58.52 163 Abandoned bridge, CC Ave (05455240, --) 78N 12W 4 NE CC Ave

60.27 117 Abandoned bridge, BB Avenue (05455220, --) 79N 12W 33 NW BB Ave

63.48 93.7 Iowa-Poweshiek County line 79N 12W 19 SW Poweshiek/Iowa 

Rd

65.04 88.9 235th Street (05455215, --) 79N 13W 23 C 235th St

66.84 81.5 State Highway 21, Guernsey (05455210, csg) 79N 13W 22 NW --

68.84 68.7 County Raod V21 (05455200, csg) 79N 13W 17 SW 200th St

70.90 61.0 180th Street (05455190, --) 79N 14W 13 SW 180th St

73.65 40.2 155th Street 79N 14W 21 N 155 St

77.45 34.0 U.S. Highway 63 (05455150, csg) 79N 15W 13 SW --

78.50 31.0 110th Street (05455140, csg) 79N 15W 14 SW 110th St

89.85 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the English and North English Rivers—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 39. English and North English Rivers, beginning at mouth of English River 

in Washington County—Continued.
84 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Farm Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 122 Mouth of Farm Creek 73N 40W 9 SE --

2.48 -- State Highway 59 73N 40W 12 SW --

4.52 104 Mills-Pottawattamie County line, Applewood Avenue 

(06807440, low)

74N 40W 36 SE Applewood Ave

5.77 -- 425th Street 74N 39W 31 N 425th St

9.90 9.9 County Road M37 74N 39W 22 W 450th St

18.11 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Farm Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 40. Farm Creek, beginning at mouth in Mills County.
SUPPLEMENTAL DATA 85

List of sites used to quantify main-channel slopes of Flint Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 148 Mouth of Flint Creek, Burlington 70N 2W 28 W --

0.97 -- State Highway 99, Burlington (05469710, --) 70N 2W 29 NE --

6.31 125 U.S. Highway 61 70N 3W 24 NW --

10.14 107 Flint Bottom Road (05469700, low) 70N 3W 16 NE Flint Bottom Rd

14.12 93.4 154th Avenue 71N 3W 32 SE 154th Ave

18.68 63.3 County Road H50 71N 4W 25 W 165th St

22.02 23.4 Diamond Road 71N 4W 22 SW Diamond Rd

30.66 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Flint Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 41. Flint Creek, beginning at mouth in Des Moines County.
86 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Flood Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 152 Mouth of Flood Creek 93N 16W 27 SW --

2.82 145 130th Street (05461400, low) 93N 16W 23 NE 130th St

7.67 127 Butler-Floyd County line (05461390, cont) 94N 16W 34 SE Floyd Line St

12.45 -- 280th Street 94N 16W 17 SW 280th St

18.80 67.9 State Highway 14 95N 17W 36 SW --

25.09 59.3 State Highway 147 (05461300, low) 95N 17W 15 NW --

30.28 47.9 Holly Street 96N 17W 32 SW Holly St

34.71 -- U.S. Highway 18, Rudd 96N 18W 24 E --

38.07 -- State Highway 122 96N 18W 14 NW --

40.87 21.3 County Road T12 96N 18W 3 W Dancer St

52.69 -- Hydrologic Regions 1 and 2 Boundary 98N 19W 36 NE --

53.45 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Flood Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 42. Flood Creek, beginning at mouth in Butler County.
SUPPLEMENTAL DATA 87

List of sites used to quantify main-channel slopes of the Floyd River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 921 Mouth of Floyd River, Sioux City 89N 47W 33 SE --

0.07 921 Interstate 29, Sioux City 89N 47W 33 SE --

0.41 921 Dace Avenue, Sioux City (06600520, qw) 89N 47W 33 NE Dace Ave

0.49 -- State Highway 12, Sioux City 89N 47W 33 NE Gordon Dr

4.14 -- U.S. Highway 75, Sioux City 89N 47W 14 NE Lewis Blvd

7.23 887 Woodbury-Plymouth County line 89N 46W 6 NW --

8.94 886 County Road C70, James (06600500, cont) 90N 46W 30 SE C70 Rd

13.86 -- County Road C60, Hinton 90N 46W 9 C C60 Rd

17.27 -- Jasmine Road 91N 46W 34 W Jasmine Rd

23.12 -- County Road C44, Merrill 91N 46W 11 NE 230th St

26.76 489 County Road C38 (06600200, low) 92N 45W 31 NW C38 Rd

27.90 -- U.S. Highway 75 92N 45W 30 NE --

31.32 -- State Highway 3, Le Mars 92N 45W 17 N Plymouth St

32.25 478 U.S. Highway 75, Le Mars (06600180, low) 92N 45W 9 W 5th Ave

36.28 -- 150th Street 93N 45W 34 NW 150th St

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Floyd River

[See section "Presentation of Curves" for explanation of list elements]

Figure 43. Floyd River, beginning at mouth in Woodbury County.
88 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

40.26 -- County Road C16 93N 45W 24 NW 130th St

45.34 292 Plymouth-Sioux County line 93N 44W 6 NE --

49.75 278 490th Street 94N 44W 28 NE 490th St

55.31 268 South County Road, Alton (06600100, cont) 94N 44W 11 NE So Co Rd

56.25 -- State Highway 60, Alton 94N 44W 2 N 3rd Ave

56.75 -- State Highway 10, Alton 94N 44W 2 NW --

60.24 249 County Road L14 95N 44W 25 SE Kingbird Ave

63.39 -- 430th Street 95N 43W 29 NE 430th St

67.84 -- 410th Street 95N 43W 16 NW 410th St

71.16 -- 395th Street, Hospers 95N 43W 3 C 395th St

74.05 -- 380th Street 96N 43W 34 NE 380th St

77.88 165 County Road B30 (06600060, low) 96N 43W 23 N 360th St

84.15 -- U.S. Highway 18, Sheldon 97N 43W 36 NE --

84.71 79.5 Sioux-O’Brien County line, County Road L26 97N 43W 25 SE McKinley Ave

86.06 -- State Highway 60, Sheldon 97N 42W 30 NE --

88.66 64.0 County Road L32 (06600020, low) 97N 42W 21 SW Nest Ave

95.36 50.2 Olive Avenue 97N 42W 12 NW Olive Ave

101.35 -- County Road B14 97N 41W 9 NW 280th St

108.86 -- State Highway 59 97N 41W 24 NW --

114.87 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Floyd River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 43. Floyd River, beginning at mouth in Woodbury County—Continued.
SUPPLEMENTAL DATA 89

List of sites used to quantify main-channel slopes of Fourmile Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 121 Mouth of Fourmile Creek 78N 23W 16 NW --

1.93 -- Des Moines Lobe landform region boundary 78N 23W 5 SW --

3.55 95.9 State Highway 163, Des Moines (05485650, qw) 78N 23W 5 N E University Ave

5.16 92.7 Easton Boulevard, Des Moines (05485640, cont) 79N 23W 32 NE Easton Blvd

6.21 -- U.S. Highway 6, Des Moines 79N 23W 29 NW E Euclid Ave

8.78 -- Interstate 80 79N 23W 17 NE --

13.47 -- County Road F38, Ankeny 80N 23W 32 NW NE 78 Ave

16.76 59.3 State Highway 931, Ankeny (05485600, low) 80N 23W 18 SW --

18.19 -- Interstate 35, Ankeny 80N 23W 7 SW --

23.54 -- U.S. Highway 69 81N 24W 36 NW --

34.83 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

8.0

8.2

8.4

8.6

8.8

9.0

9.2

9.4

9.6

9.8

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Fourmile Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 44. Fourmile Creek, beginning at mouth in Polk County.
90 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Fox River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 188 Iowa-Missouri State line 67N 9W 17 SE --

1.37 -- County Road J56, Mount Sterling (05494600, qw) 67N 9W 7 C West Rd

4.87 173 Jersey Avenue 68N 10W 34 S Jersey Ave

8.70 161 State Highway 2 (05494500, cont) 68N 10W 30 SW --

13.82 146 County Road V56 (05494450, qw) 68N 11W 17 NE Rte V56

16.63 134 Van Buren-Davis County line 68N 11W 6 NW --

17.97 -- County Road V50 68N 12W 2 NE Wheat Ave

22.12 117 County Road V42 68N 12W 5 NE Timber Ave

26.35 -- County Road J40 (05494350, qw) 69N 13W 27 E 215th Ave

30.19 -- U.S. Highway 63, Bloomfield 69N 13W 19 NE --

30.98 87.7 County Road V20, Bloomfield (05494300, cont) 69N 14W 13 SE Lilac Ave

35.11 75.5 Ice Avenue 69N 14W 9 SW Ice Ave

39.12 -- Flora Avenue (05494250, qw) 69N 15W 24 NE Flora Ave

41.62 -- Driftwood Boulevard (05494200, qw) 69N 15W 27 NW Driftwood Blvd

43.70 -- Cedar Avenue 69N 15W 28 NW Cedar Ave

52.84 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

5

6

7

8

9

10

11

12

13

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Fox River

[See section "Presentation of Curves" for explanation of list elements]

Figure 45. Fox River, beginning at Iowa-Missouri State line in Van Buren County.
SUPPLEMENTAL DATA 91

List of sites used to quantify main-channel slopes of the Grand River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 206 Iowa-Missouri State line 67N 31W 30 SE --

0.22 206 County Road (06896150, low) 67N 31W 29 SW --

3.99 195 County Road J55 67N 31W 15NW --

6.92 185 County Road 67N 31W 1 NW --

9.65 -- County Road J43 68N 30W 19 SW --

12.40 -- State Highway 2 68N 30W 7 NE --

16.77 90.6 County Road 69N 30 19 NW --

19.07 -- State Highway 66 69N 30W 6 SE --

21.19 67.5 County Road J23, Knowlton (06896100, low) 70N 30W 29 SE --

23.95 43.1 County Road J20 70N 30W 21 N --

28.69 22.3 Ringgold-Union County line, Shannon City 70N 30W 1 NW 1st St (Old IA 260)

42.48 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Grand River

[See section "Presentation of Curves" for explanation of list elements]

Figure 46. Grand River, beginning at Iowa-Missouri State line in Ringgold County.
92 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Hardin Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 168 Mouth of Hardin Creek 83N 30W 23 SW --

2.64 -- 243rd Street 83N 30W 14 SW 243rd St

5.95 161 Parkland Avenue (05483050, low) 83N 30W 10 NW Parkland Ave

8.20 159 U.S. Highway 30 83N 30W 4 NE --

12.11 -- State Highway 4 84N 30W 29 SW --

13.75 -- Hydrologic Regions 1 and 2 boundary 84N 30W 30 NW --

15.41 107 M Avenue 84N 30W 19 NW M Ave

18.36 101 180th Street (05482900, csg) 84N 31W 14 NW 180th St

55.57 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Hardin Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 47. Hardin Creek, beginning at mouth in Greene County.
SUPPLEMENTAL DATA 93

List of sites used to quantify main-channel slopes of Hartgrave Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 185 Mouth of Hartgrave Creek 92N 18W 34 SE --

1.11 183 County Road T16 (05458785, --) 92N 18W 33 SE Douglas Ave

2.97 -- State Highway 3 92N 18W 32 NE South St

5.52 176 Butler-Franklin County line, Franklin Avenue 92N 18W 30 NW Franklin Ave

7.71 168 Wren Avenue 92N 19W 26 C Wren Ave

8.99 -- Hydrologic Regions 1 and 2 boundary 92N 19W 34 NE --

10.22 161 Vine Avenue (05458780, low) 92N 19W 34 NW Vine Ave

45.73 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11

7.0

7.2

7.4

7.6

7.8

8.0

8.2

8.4

8.6

8.8

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Hartgrave Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 48. Hartgrave Creek, beginning at mouth in Butler County.
94 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Honey Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 110 Mouth of Honey Creek 85N 19W 27 W --

2.99 95.6 County Road E18 (05451350, low) 85N 19W 16 W Marble Rd

6.43 -- Marshall-Hardin County line 85N 19W 6 NE --

10.47 -- County Road D65 86N 20W 24 W Co Hwy D65

13.60 66.5 County Road S57 (05451300, low) 86N 20W 16 E Co Hwy S57

15.11 -- Des Moines Lobe landform region boundary 86N 20W 17 SE --

17.96 57.6 295th Street 86N 20W 7 NE 295th St

19.91 42.6 M Avenue 86N 21W 12 NW M Ave

23.47 -- U.S. Highway 65, Hubbard 87N 21W 33 SW --

25.31 20.1 State Highway 175 87N 21W 31 N --

33.49 -- Hydrologic Regions 1 and 2 boundary 87N 22W 18 SW --

35.97 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Honey Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 49. Honey Creek, beginning at mouth in Marshall County.
SUPPLEMENTAL DATA 95

List of sites used to quantify main-channel slopes of Indian Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 184 Mouth of Indian Creek 75N 37W 17 NE --

0.80 183 Nishna Valley Road (06809400, low) 75N 37W 8 SW Nishna Valley Rd

1.62 -- U.S. Highway 6 75N 37W 8 NW --

3.68 175 Lansing Road 76N 37W 32 NW Lansing Rd

7.89 -- County Road G30 76N 37W 8 NW Highland Rd

11.01 -- State Highway 83 77N 37W 29 NW --

15.05 -- Interstate 80 77N 37W 6 E --

15.67 117 Cass-Shelby County line 77N 37W 5 NW --

18.69 67.4 400th Street (06809350, low) 78N 37W 20 N 400th St

22.06 -- County Road F58 78N 37W 5 NW 660th St

25.68 31.4 Shelby-Audubon County line, Yellowwood Road 79N 37W 36 NE Yellowwood Rd

27.13 -- State Highway 173, Kimballton 79N 36W 30 SE S Main St

28.09 -- State Highway 44, Kimballton 79N 36W 29 NW --

38.42 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Indian Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 50. Indian Creek, beginning at mouth in Cass County.
96 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Indian and East Indian Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 413 Mouth of Indian Creek 80N 20W 32 NE --

0.24 -- Interstate 80 80N 20W 32 NE --

2.22 410 North 19th Avenue West (05471370, --) 80N 20W 29 SW N 19th Ave W

4.69 395 North 51st Avenue West 80N 20W 18 NW N 51st Ave W

8.53 285 County Road F24, Mingo (05471250, --) 80N 21W 3 NE Hwy F-24 W

8.80 -- Des Moines Lobe landform region boundary 81N 21W 34 SW --

11.52 276 State Highway 117 (05471200, cont) 81N 21W 28 NW --

11.67 -- U.S. Highway 65 81N 21W 20 SE --

14.47 247 Jasper-Polk County line 81N 21W 18 NW --

18.10 219 Polk-Story County line 82N 22W 34 SE --

20.55 -- State Highway 210, Maxwell 82N 22W 27 SW --

23.39 203 County Road E63 (05471180, low) 82N 22W 16 C 305th St

27.30 126 County Road S27 (05471120, qw) 83N 22W 34 SW 650th Ave

30.30 121 260th Street 83N 22W 27 NE 260th St

33.90 -- U.S. Highway 30 83N 22W 14 NE --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

5

6

7

8

9

10

11

12

13

14

Indian Creek East Indian Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Indian and East Indian Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 51. Indian and East Indian Creeks, beginning at mouth of Indian Creek in Jasper County.
SUPPLEMENTAL DATA 97

38.63 65.7 220th Street (05471100, low) 83N 22W 2 NE 220th St

41.74 51.8 200th Street 84N 22W 26 NE 200th St

48.49 37.2 170th Street 84N 22W 11 NE 170th St

52.87 26.3 650th Avenue 85N 22W 27 SW 650th Ave

65.46 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of Indian and East Indian Creeks—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 51. Indian and East Indian Creeks, beginning at mouth of Indian Creek in Jasper 

County—Continued.
98 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Iowa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 2,904 Johnson-Iowa County line 81N 9W 36 NE --

2.17 2,864 U.S. Highway 151 (05453180, qw) 81N 9W 35 SW --

12.15 2,842 State Highway 220 81N 10W 36 NW --

21.83 2,794 County Road V66, Marengo (05453100, cont) 81N 11W 24 NE M Ave

33.23 -- F Avenue 81N 12W 12 NW F Ave

41.38 2,455 State Highway 21 (05452500, cont) 81N 12W 5 NW --

42.00 -- Iowa-Benton County line 81N 12W 6 N --

42.67 -- Benton-Tama County line 82N 13W 36 SE --

46.32 -- 380th Street 82N 13W 26 NW 380th St

50.82 2,076 County Road V18, Chelsea 82N 13W 19 NE Hwy V18

56.32 -- 360th Street 82N 14W 13 NW 360th St

61.11 2,009 P Avenue (05451820, qw) 82N 14W 4 SE P Ave

69.99 1,987 U.S. Highway 63, Tama (05451810, qw) 83N 15W 34 SE State St

75.01 1,882 County Road E49 83N 15W 31 NE Hwy E49

81.66 -- County Road T47, Montour 83N 16W 22 SW E Ave

DISTANCE UPSTREAM FROM JOHNSON-IOWA COUNTY LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Iowa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 52. Iowa River, beginning at Johnson-Iowa County line.
SUPPLEMENTAL DATA 99

83.22 1,830 U.S. Highway 30 83N 16W 16 NE --

88.44 1,800 Tama-Marshall Co. line, Abbott Ave. 83N 16W 6 NW Abbott Ave

91.50 -- Three Bridge Road 83N 17W 3 SE Three Bridge Rd

95.58 1,635 County Road E35 84N 17W 29 SE Main St Rd

100.36 1,532 State Highway 14, Marshalltown (05451500, cont) 84N 18W 23 SE N 3rd Ave

101.09 1,500 Center Street, Marshalltown (05451490, qw) 84N 18W 26 NW Airport Rd

107.27 1,466 State Highway 330 (05451460, qw) 84N 19W 13 NE --

111.79 1,288 County Road E23 85N 19W 27 SW 148th St

115.22 1,170 County Road E18 (05451285, qw) 85N 19W 11 NW Marble Rd

116.74 1,139 Marshall-Hardin County line 85N 19W 2 NW --

121.29 1,122 County Road D65 86N 19W 22 SE Co Hwy D65

125.09 1,090 County Road D55 (05451275, qw) 86N 19W 4 SW 290th St

127.57 779 County Road D53 87N 19W 28 SW 270th St

131.77 765 State Highway 175, Eldora 87N 19W 8 NE Eddington Ave

137.63 -- County Road D35, Steamboat Rock (05450400, qw) 88N 19W 28 NW Main St

140.48 -- Des Moines Lobe landform region boundary 88N 19W 16 NE --

144.44 722 County Road D25 88N 20W 12 SE 170th St

149.98 714 RR Avenue 89N 19W 31 NE RR Ave

155.48 702 OO Avenue 89N 20W 34 NE OO Ave

161.98 -- U.S. Highways 20 and 65, Iowa Falls 89N 21W 13 SE Oak St

162.44 665 Washington Avenue, Iowa Falls (05450000, cont) 89N 21W 13 SE Washington Ave

164.94 646 State Highway 941 89N 21W 15 SE --

167.64 638 State Highway 941 89N 21W 17 SE --

172.90 614 Hardin-Franklin County line 89N 22W 1 NW --

175.66 -- Hydrologic Regions 1 and 2 boundary 90N 22W 35 SE --

253.53 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Iowa River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 52. Iowa River, beginning at Johnson-Iowa County line.
100 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Kanaranzi Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 205 Mouth of Kanaranzi Creek 100N 45W 28 SW --

1.88 203 County Road K52 (06483260, low) 100N 45W 22 SW Harrison St

3.80 -- County Road A16 100N 45W 15 SE 120th St

6.46 197 Southwest corner of section 11 100N 45W 11 SW --

7.80 -- Iowa-Minnesota State line, 100th St 100N 45W 11 NE 100th St

66.07 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

012345678

6.0

6.1

6.2

6.3

6.4

6.5

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Kanaranzi Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 53. Kanaranzi Creek, beginning at mouth in Lyon County.
SUPPLEMENTAL DATA 101

List of sites used to quantify main-channel slopes of Keg Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Mouth of Keg Creek 71N 43W 6 SE --

1.82 -- Interstate 29 72N 43W 33 W --

4.33 190 Kane Avenue (06805900, low) 72N 43W 27 NE Kane Ave

5.87 -- U.S. Highway 34, Glenwood 72N 43W 14 SE --

9.32 163 County Road H20 72N 42W 6 NE Gaston Ave

13.47 149 County Road L45 73N 42W 17 NW 250th St

15.68 137 Mills-Pottawattamie County line, Applewood Avenue 73N 42W 5 NE Applewood Ave

17.75 131 Pioneer Trail (06805800, low) 74N 42W 28 NW Pioneer Trail

20.83 -- State Highway 92 74N 42W 9 NE --

24.89 -- U.S. Highway 6 75N 42W 22 NW --

27.78 91.4 Honeysuckle Road 75N 42W 11 NE Honeysuckle Rd

33.72 81.0 County Road G30 76N 41W 19 NE Magnolia Rd

38.24 70.5 Rosewood Road 76N 41W 4 NW Rosewood Rd

42.78 59.6 County Road L66, Minden (06805700, low) 77N 41W 15 SE County Rd

43.50 -- State Highway 83 77N 41W 14 NW --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Keg Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 54. Keg Creek, beginning at mouth in Mills County.
102 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

45.55 -- Interstate 80 77N 41W 2 NW --

46.10 50.4 Pottawattamie-Harrison County line, York Road 77N 41W 2 N York Rd

49.57 -- 315th Street 78N 41W 23 N 315th St

52.42 29.4 Harrison-Shelby County line, Dogwood Road 78N 41W 1 SE Dogwood Ave

64.80 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of Keg Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 54. Keg Creek, beginning at mouth in Mills County—Continued.
SUPPLEMENTAL DATA 103

List of sites used to quantify main-channel slopes of the Little Cedar River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 323 Mouth of Little Cedar River 94N 14W 20 NW --

1.24 -- State Highway 346 94N 14W 17 E --

4.20 -- 250th Street 94N 14W 4 NW 250th St

7.61 306 County Road B57 (05458000, cont) 95N 14W 21 NE 220th St

12.89 280 U.S. Highway 18 (05457990, --) 95N 14W 6 SW 200th St

13.21 279 Chickasaw-Floyd County line 95N 14W 6 SW --

17.89 270 170th Street 96N 15W 23 SW 170th St

23.58 -- 140th Street 96N 15W 8 N 140th St

29.18 234 110th Street (05457950, qw) 97N 16W 24 SW 110th St

30.61 227 Floyd-Mitchell County line 97N 16W 24 N --

36.65 200 County Road A57 97N 15W 5 NW 340th St

39.61 193 State Highway 9 (05457900, --) 98N 15W 19 SE --

45.34 126 County Road T54 98N 16W 1 NE Shadow Ave

51.10 100 County Road A31, Little Cedar (05457850, --) 99N 16W 15 SE 430th St

55.43 -- 450th Street 99N 16W 8 N 450th St

60.98 77.3 County Road A19 (05457800, low) 100N 16W 19 NE 490th St

66.86 50.6 Iowa-Minnesota State line 100N 16W 9 NW State Line St

87.33 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Cedar River

[See section "Presentation of Curves" for explanation of list elements]

Figure 55. Little Cedar River, beginning at mouth in Chickasaw County.
104 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Little Maquoketa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 157 Mouth of Little Maquoketa River 90N 2E 25 SW --

4.13 139 U.S. Highway 52 90N 2E 34 SW --

6.84 130 Clay Hill Road (05414500, cont) 89N 2E 5 NE Clay Hill Rd

9.84 -- County Road Y21 89N 2E 6 SW Cedar Ridge Rd

15.39 -- Asbury Road 89N 1E 16 SE Asbury Rd

17.92 39.6 Potter Hill Drive (05414350, csg) 89N 1E 20 SE Potter Hill Dr

20.14 -- Lattnerville Lane 89N 1E 31 NE Lattnerville Ln

30.22 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22

14

16

18

20

22

24

26

28

30

32

34

36

38

40

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Maquoketa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 56. Little Maquoketa River, beginning at mouth in Dubuque County.
SUPPLEMENTAL DATA 105

List of sites used to quantify main-channel slopes of the Little Rock River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 474 Mouth of Little Rock River 98N 46W 35 SW --

0.76 474 County Road K42 (06483490, low) 98N 46W 36 W Garfield St

2.91 471 County Road A52 (06483487, --) 98N 45W 31 NE 260th St

5.07 -- U.S. Highway 75 98N 45W 29 NE --

9.65 -- County Road K52 98N 45W 15 SE Hickory St

13.69 -- County Road K60 98N 45W 12 NE Indian St

17.21 416 County Road K64 (06483485, --) 98N 44W 17 SE Jackson St

21.07 199 230th Street (06483400, low) 98N 44W 15 NE 230th St

24.08 195 County Road L14, George (06483390, --) 98N 44W 2 SE Virginia St

28.33 181 County Road A34 98N 43W 5 NE 210th St

33.48 -- County Road A22 99N 43W 20 NE 180th St

36.81 -- 160th Street 99N 43W 9 NW 160th St

39.86 134 State Highway 9 (06483380, low) 99N 43W 3 NE --

44.44 125 Lyon-Osceola County line, McKinley Street 100N 43W 25 NE McKinley St

47.30 -- 120th Street 100N 42W 19 NE 120th St

50.68 92.0 Iowa-Minnesota State line, County Road (06483360, low) 100N 42W 7 NW --

77.57 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Rock River

[See section "Presentation of Curves" for explanation of list elements]

Figure 57. Little Rock River, beginning at mouth in Lyon County.
106 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Little Sioux River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Mouth of Little Sioux River 81N 45W 27 NE --

0.47 -- Interstate 29 81N 45W 23 SW --

1.11 3,600 County Road K45, River Sioux (06607513, qw) 81N 45W 23 SE Austin Ave

5.89 -- Harrison-Monona County line 81N 44W 5 NW --

8.83 -- County Road E60 (06607510, cont) 82N 44W 21 NW Co Rd E60

13.41 3,526 County Road E54 (06607500, cont) 83N 44W 33 NE 270th St

17.24 -- State Highway 175 83N 44W 9 NW --

21.66 -- Equalizer ditch, joins Little Sioux River and MononaHarrison ditch84N 44W 19 NW --

21.86 2,738 Larpenteur Memorial Road (06606700, cont) 84N 44W 18 SW Larpenteur 

Memorial Rd

23.69 -- Nutmeg Avenue 84N 44W 7 NE Nutmeg Ave

28.47 -- County Road E16 85N 44W 16 SE Co Rd E16

32.12 2,697 Monona-Woodbury County line 85N 44W 2 NE --

33.22 2,686 State Highway 141, Smithland 86N 44W 36 NW --

38.03 2,663 County Road D54, Oto 86N 43W 7 NE 290th St

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 20 40 60 80 100 120 140 160 180 200 220 240

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Sioux River

[See section "Presentation of Curves" for explanation of list elements]

Figure 58. Little Sioux River, beginning at mouth in Harrison County.
SUPPLEMENTAL DATA 107

43.72 2,624 County road 87N 43W 8 SW --

46.93 -- County Road D38, Anthon 88N 43W 33 SW 220th St

52.06 2,554 Mason Avenue 88N 43W 21 NE Mason Ave

58.80 2,500 State Highway 31, Correctionville (06606600, cont) 88N 43W 1 NW --

59.84 -- U.S. Highway 20, Correctionville 89N 42W 34 SW --

67.31 2,416 Woodbury-Ida County line 89N 42W 12 SE --

69.97 2,385 Ida-Cherokee County line 89N 41W 6 N --

72.14 2,383 County Road C66, Washta 90N 41W 31 NE Main St

82.69 -- County Road L51, Quimby 90N 41W 1 SW L Ave

86.32 2,269 County road 91N 40W 32 NW --

89.81 2,205 County Road C44 91N 40W 28 NE 580th St

96.94 -- U.S. Highway 59, Cherokee 92N 40W 34 NE S 2nd St

97.95 2,173 State Highway 977, Cherokee (06606400, low) 92N 40W 35 N --

98.84 -- State Highway 3, Cherokee 92N 40W 26 NE --

105.80 1,861 480th Street 92N 40W 1 NE 480th St

111.09 1,842 County Road C16 93N 39W 21 NW 450th St

117.42 1,813 Cherokee-Obrien County line 93N 39W 3 NE --

119.77 -- State Highway 10 94N 39W 27 SE --

120.89 1,803 Abandoned bridge, Yellow Avenue (06606100, low) 94N 39W 26 NW --

123.61 1,644 Obrien-Clay County line 94N 39W 25 NE --

126.79 1,640 State Highway 10, Peterson 94N 38W 32 NE --

131.77 1,629 Clay-Buena Vista County line 94N 38W 35 SW --

139.38 1,548 County Road M36, Linn Grove (06605850, cont) 93N 37W 5 SW 80th Ave

148.43 1,519 U.S. Highway 71, Sioux Rapids 93N 37W 1 SE --

152.45 1,507 Buena Vista-Clay County line 93N 36W 5 NE --

159.11 1,494 County Road B63 94N 36W 20 NW 480th St

164.22 1,366 County Road M50 95N 36W 35 SW 260th Ave

167.38 1,334 County Road B53, Gillett Grove (06605600, cont) 95N 36W 25 C 435th St

175.24 1,312 County Road B40 95N 36W 2 NW 390th St

180.27 -- U.S. Highway 18 96N 36W 22 N --

185.26 990 U.S. Highways 71 and 18, Spencer (06605100, cont) 96N 36W 18 NW N Grand Ave

191.71 546 210th Avenue 96N 37W 1 W 210th Ave

197.59 541 U.S. Highway 18 97N 37W 34 NE --

202.03 -- 300th Street 97N 37W 20 N 300th St

207.41 513 Clay-Dickinson County line 97N 37W 5 NW --

211.23 502 County Road A43 98N 37W 34 N 260th St

216.85 333 225th Street (06603900, low) 98N 37W 11 C 225th St

220.69 -- 190th Avenue 98N 37W 15 SW 190th Ave

224.29 -- Hydrologic Regions 1 and 2, and Des Moines Lobe 

landform region boundaries

98N 37W 3 N --

226.26 310 210th Street 98N 37W 4 NW 210th St

268.49 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Little Sioux River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 58. Little Sioux River, beginning at mouth in Harrison County—Continued.
108 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Little Turkey River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 355 Mouth of Little Turkey River 95N 8W 18 NW --

4.34 -- County Road B44 95N 9W 26 SE Nature Rd

8.27 335 275th Street 95N 9W 34 NW 275th St

11.78 319 Sunset Road (05411800, low) 95N 9W 30 SW Sunset Rd

14.16 102 Spruce Road (05411620, low) 95N 10W 25 NW Spruce Rd

19.42 -- State Highway 193, Waucoma 95N 10W 9 SW Riverview Dr

22.31 80.7 Fayette-Winneshiek County line 95N 10W 5 NW --

24.42 -- State Highway 24 96N 10W 30 SE --

25.91 72.4 Winneshiek-Chickasaw County line 96N 10W 30 NW --

30.04 -- County Road B33 96N 11W 14 S 160th St

32.90 54.7 County Road V56 96N 11W 10 NW Union Rd

37.64 37.9 County Road B22 97N 11W 32 NE 120th St

41.96 30.5 Chickasaw-Howard County line, County Road B16 97N 11W 19 NW 100th St

44.36 23.8 200th Street 97N 12W 13 NE 200th St

53.25 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Turkey River

[See section "Presentation of Curves" for explanation of list elements]

Figure 59. Little Turkey River, beginning at mouth in Fayette County.
SUPPLEMENTAL DATA 109

List of sites used to quantify main-channel slopes of the Little Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 206 Mouth of Little Wapsipinicon River, Littleton 89N 10W 9 NE --

0.61 147 Clayton Boulevard (05420900, low) 89N 10W 4 SE Clayton Blvd

4.55 144 145th Street (05420860, low) 90N 10W 28 C 145th St

11.22 -- State Highway 281, Fairbank 90N 10W 5 NW Main St

11.47 125 Buchanan-Fayette County line 90N 10W 5 NW --

16.14 99.2 40th Street 91N 10W 21 NW 40th St

19.19 94.1 State Highway 3 (05420850, csg) 91N 10W 9 NW --

25.96 -- County Road C33 92N 10W 19 N 100th St

27.71 57.4 Fayette-Bremer County line, County Road V62 

(05420840, low)

92N 10W 18 NW Y Ave

31.85 49.9 160th Street 92N 11W 2 NE 160th St

35.99 41.4 Bremer-Fayette County line 93N 11W 25 NE --

38.74 -- State Highway 93 93N 10W 30 NE 150th St

40.55 26.0 Fayette-Bremer County line, 160th Street 93N 10W 19 NE 160th St

54.81 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Wapsipinicon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 60. Little Wapsipinicon River, beginning at mouth in Buchanan County.
110 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Little Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 125 Mouth of Little Wapsipinicon River 94N 13W 3 NW --

5.07 -- County Road B57 95N 13W 16 SE 220th St

7.71 95.0 U.S. Highway 18 (05420650, csg) 95N 13W 9 NW --

13.51 79.0 165th Street, North Washington 96N 13W 20 W 165th St

18.69 50.9 130th Street 96N 14W 1 NE 130th St

23.43 45.7 Chickasaw-Howard County line, 100th Street 97N 14W 24 NW 100th St

26.27 37.3 County Road B17, Elma (05420640, csg) 97N 14W 12 NW 190th St

32.23 19.0 County Road A46 98N 14W 22NE 150th St

42.04 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Little Wapsipinicon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 61. Little Wapsipinicon River, beginning at mouth in Chickasaw County.
SUPPLEMENTAL DATA 111

List of sites used to quantify main-channel slopes of Long and East Long Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 124 Mouth of Long Creek 69N 26W 8 SW --

5.14 117 County Roads J20 and R34 (06897940, low) 70N 26W 32 NE --

11.29 -- County road 70N 26W 16 NW --

16.26 51.2 Decatur-Clarke County line 70N 26W 6 NW --

19.04 -- Church Street 71N 27W 26 NE Church St

21.39 21.0 County Road H45 71N 27W 14 N Elk St

33.11 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Long Creek East Long Creek

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Long and East Long Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 62. Long and East Long Creeks, beginning at mouth of Long Creek in Decatur County.
112 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Long and South Fork Long Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Mouth of Long Creek 74N 4W 1 C --

1.58 155 115th Street (05465310, qw) 74N 4W 11 E 115th St

4.95 146 County Road X37 (05465300, low) 74N 4W 23 S County Rd X 37

9.04 -- Q Avenue 74N 4W 16 SW Q Ave

16.31 90.7 County Road X17 74N 5W 12 NW County Rd X 17

19.43 82.2 County Road G52 74N 5W 3 NW County Rd G 52

25.37 71.9 Louisa-Washington County line 75N 5W 30 SW --

28.21 68.4 Yucca Avenue (05465200, low) 75N 6W 26 SE Yucca Ave

31.06 31.3 U.S. Highway 218 (05465180, --) 75N 6W 27 SW --

35.56 -- County Road G6W 75N 6W 19 SW Spruce Ave

37.42 16.4 State Highway 92 (05465175, --) 75N 7W 23 NE --

50.35 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Long Creek South Fork Long Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Long and South Fork Long Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 63. Long and South Fork Long Creeks, beginning at mouth of Long Creek in Louisa County.
SUPPLEMENTAL DATA 113

List of sites used to quantify main-channel slopes of Lost Island Outlet Pickerel Run, and Joint drainage ditch 61,—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 156 Mouth of Lost Island Outlet 96N 36W 35 NE --

3.20 151 County Road M54 (06605500, low) 96N 35W 19 SW 280th Ave

4.89 -- U.S. Highway 18, Dickens 96N 35W 19 NE --

5.13 103 Mouth of Pickerel Run 96N 35W 17 SW --

6.41 -- Des Moines Lobe landform region boundary 96N 35W 18 NE --

10.29 80.7 290th Avenue 97N 35W 32 NW 290th Ave

12.89 75.7 County Road N14 (06605400, low) 97N 35W 27 NW 310th Ave

15.38 45.6 Mouth of Joint drainage ditch 61,Trumbull Lake 97N 35W 22 SE --

19.45 26.2 Clay-Dickinson County line, 270th Street 97N 35W 3 NW 270th St

22.94 19.0 County Road A48 98N 35W 23 NW 240th St

29.60 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Lost Island Outlet Pickerel Run Joint Drainage Ditch 61

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Lost Island Outlet, Pickerel Run, and Joint drainage ditch 61

[See section "Presentation of Curves" for explanation of list elements]

Figure 64. Lost Island Outlet, Pickerel Run, and Joint drainage ditch 61, beginning at mouth of Lost Island 

Outlet in Clay County.
114 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Lytle Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 116 Mouth of Lytle Creek 85N 2E 8NE --

1.38 114 188th Street (05418350, low) 85N 2E 5 C 188th St

5.94 -- County Road D61 86N 2E 21 SE Bellevue-Cascade 

Rd

14.52 -- 287th Street 86N 2E 6 SE 287th St

16.69 62.7 Jackson-Dubuque County line 86N 2E 6 NW --

17.02 62.7 Washington Mills Road (05418300, low) 87N 1E 36 SE Washington Mills 

Rd

20.12 57.3 Lyons Road 87N 2E 30 NE Lyons Rd

22.52 41.8 Below mouth of Prairie Creek 87N 1E 24 SE --

34.01 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

8

9

10

11

12

13

14

15

16

17

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Lytle Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 65. Lytle Creek, beginning at mouth in Jackson County.
SUPPLEMENTAL DATA 115

List of sites used to quantify main-channel slopes of the Maple River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 742 Mouth of Maple River 83N 44W 17 SE --

1.18 741 County Road L14 (06607400, low) 83N 44W 10 SW Larpenteur 

Memorial Rd

1.92 734 State Highway 175, Turin (06607300, cont) 83N 44W 10NW --

6.43 722 County Road L20, Castana 84N 44W 24 N L20

11.26 -- State Highway 175 84N 43W 4 SW --

15.98 669 State Highway 175, Mapleton (06607200, cont) 85N 43W 23 SE --

17.70 -- State Highway 141, Mapleton 85N 42W 14 SE 4th St

22.28 628 Monona-Woodbury County line 85N 42W 5 N --

26.62 -- 320th Street, Danbury 86N 42W 26 N 320th St

30.47 567 Woodbury-Ida County line 86N 41W 18 W --

32.61 -- 290th Street 86N 41W 7 NE 290th St

37.10 -- County Road L51, Battle Creek 87N 41W 35 NW Dodge Ave

41.79 451 German Avenue 87N 40W 20 NW German Ave

46.56 -- U.S. Highway 59 and State Highway 175, Ida Grove 87N 40W 15 NE --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

3

4

5

6

7

8

9

10

11

12

13

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Maple River

[See section "Presentation of Curves" for explanation of list elements]

Figure 66. Maple River, beginning at mouth in Monona County.
116 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

48.85 364 Keystone Avenue (06606900, low) 87N 40W 12 NW Keystone Ave

54.33 -- 200th Street 88N 40W 25 NW 200th St

60.28 -- U.S. Highway 20 88N 39W 6 NW --

63.27 -- County Road D15, Galva 89N 39W 27 NE 140th St

67.98 182 Ida-Cherokee County line 89N 39W 3 NW --

71.57 -- 630th Street 90N 39W 20 NE 630th St

78.86 -- 590th Street 91N 39W 32 N 590th St

85.44 85.2 550th Street (06606800, low) 91N 39W 8 NW 550th St

88.59 -- State Highway 3 92N 39W 33 N --

100.85 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Maple River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 66. Maple River, beginning at mouth in Monona County—Continued.
SUPPLEMENTAL DATA 117

List of sites used to quantify main-channel slopes of the Maquoketa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,879 Mouth of Maquoketa River 85N 6E 7 SW --

2.20 1,875 U.S. Highway 52 (05418720, --) 85N 5E 23 NE --

7.15 1,861 County Road Z34 84N 5E 4 NW 435th Ave

11.22 -- County Road Z20, Spragueville 84N 4E 13 SE 387th Ave

19.51 -- County Road E23Y 84N 4E 8 NE Iron Bridge Rd

27.60 1,553 State Highway 62 (05418500, cont) 84N 3E 17 NE --

31.72 -- U.S. Highway 61, Maquoketa 84N 2E 24 NW --

40.26 938 74th Street (05418000, cont) 84N 1E 13 NW 74th St

44.30 812 County Road Y34 84N 1E 3 NE 50th Ave

47.06 -- 30th Avenue 85N 1E 33 SW 30th Ave

53.45 748 Jackson-Jones County line 85N 1E 18 SW --

59.02 -- Temple Hill Road 85N 1W 8 SE Temple Hill Rd

61.86 704 State Highway 136 (05417600, low) 85N 1W 6 N --

66.84 692 Ebys Mill Road 85N 2W 3 SE Ebys Mill Rd

81.50 -- U.S. Highway 151, Monticello 86N 3W 22 C Main St

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

3

4

5

6

7

8

9

10

11

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Maquoketa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 67. Maquoketa River, beginning at mouth in Jackson County.
118 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

83.00 600 State Highway 38 86N 3W 16 NE --

87.54 526 Jones-Delaware County line 86N 3W 6 N --

92.17 -- County Road D47, Hopkinton 87N 4W 24 NW Marion St

94.40 454 295th Street (05417560, low) 87N 4W 11 NE 295th St

97.09 -- Quarter Road 88N 4W 34 E Quarter Rd

101.58 347 County Road X31 (05417500, cont) 88N 4W 30 NE 230th Ave

109.40 -- County Road X21 88N 5W 15 NE 240th St

111.18 305 Discontinued gage near Pin Oak County Park (05417000, 

cont)

88N 5W 9 NE --

113.26 275 U.S. Highway 20 (05416900, cont) 89N 5W 33 SW --

114.76 -- State Highway 13, Manchester 89N 5W 29 SW West Main St

117.04 -- 195th Street 89N 5W 19 NE 195th St

121.34 -- 165th Street 89N 6W 1 W 165th St

125.52 -- County Road C64, Dundee 90N 6W 23 W Richland St

131.32 61.1 Backbone State Park Road (05416300, low) 90N 6W 9 SW Backbone

134.74 42.6 Delaware-Clayton County line, 400th St 90N 6W 5 NW 400th St

138.98 19.0 Clayton-Fayette County line 91N 6W 19 W --

139.73 -- State Highway 3 91N 7W 13 SE --

149.66 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Maquoketa River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 67. Maquoketa River, beginning at mouth in Jackson County—Continued.
SUPPLEMENTAL DATA 119

List of sites used to quantify main-channel slopes of Maynes Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 135 Mouth of Maynes Creek 91N 17W 7 SW --

0.79 -- Grand Avenue (05458870, qw) 91N 17W 18 NW Grand Ave

5.26 121 County Road T16 (05458850, low) 91N 18W 15 SW Douglas Ave

9.55 115 Butler-Franklin County line, Franklin Avenue 91N 18W 18 NW Franklin Ave

10.49 -- Hydrologic Regions 1 and 2 boundary 91N 19W 12 SW --

16.11 97.8 County Road S56 (05458820, --) 91N 19W 18 NE Thrush Ave

43.53 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

8.0

8.2

8.4

8.6

8.8

9.0

9.2

9.4

9.6

9.8

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Maynes Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 68. Maynes Creek, beginning at mouth in Butler County.
120 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Middle Nodaway River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 341 Mouth of Middle Nodaway River 71N 36W 33 SW --

0.79 341 U.S. Highway 71 (06816900, low) 71N 36W 33 NE --

2.91 -- County Road H54, Villisca 71N 36W 24 NW Third St

6.86 -- U.S. Highway 34 71N 36W 1 C --

8.52 318 Montgomery-Adams County line, County Road H34 72N 35W 31 NE 210th St

12.51 -- 190th Street 72N 35W 15 SW 190th St

15.25 -- County Road N28, Carbon 72N 35W 12 W B St

18.72 274 County Road H24 73N 34W 32 NE 150th St

20.76 -- State Highway 148 73N 34W 27 NW --

22.58 256 Juniper Avenue 73N 34W 14 SW Juniper Ave

25.99 -- 110th Street 73N 33W 7 NE 110th St

27.06 225 Adams-Adair County line 73N 33W 6 NE --

28.91 -- Downstream of mouth of West Fork Middle Nodaway 

River

74N 33W 33 N --

28.91 -- Upstream of mouth of West Fork Middle Nodaway River 74N 33W 33 N --

29.44 89.3 Delta Avenue (06816600, low) 74N 33W 33 NE Delta Ave

34.01 79.6 County Road G61 74N 33W 24 NE 310th St

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Middle Nodaway River

[See section "Presentation of Curves" for explanation of list elements]

Figure 69. Middle Nodaway River, beginning at mouth in Montgomery County.
SUPPLEMENTAL DATA 121

38.03 61.7 County Road N72 74N 32W 5 SW Fontanelle Rd

40.60 48.2 County Road G49 75N 32W 33 NW 270th St

46.30 35.6 State Highway 92 75N 32W 14 N --

49.42 27.8 220th Street 75N 32W 1 NW 220th St

60.62 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Middle Nodaway River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 69. Middle Nodaway River, beginning at mouth in Montgomery County—Continued.
122 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Middle Raccoon River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 609 Mouth of Middle Raccoon River 78N 29W 9 NE --

1.56 609 County Road F59, Redfield (05483660, low) 78N 29W 4 NW Thomas St

7.55 -- Amarillo Avenue 79N 29W 30 SE Amarillo Ave

8.60 484 Dallas-Guthrie County line 79N 29W 31 NW --

12.88 -- 248th Trail 79N 30W 15 SE 248th Tr

18.16 440 Soldier Trail, Panora (05483600, cont) 79N 30W 5 NW River Rd

19.25 -- State Highway 44 80N 30W 31 SE --

26.74 -- County Road P18 80N 31W 9 SE 180th Tr

30.23 375 State Highway 25 (05483450, cont) 81N 31W 32 SW --

34.36 -- 150th Street 81N 32W 35 NE 150th St

40.65 -- 140th Street 81N 32W 29 NW 140th St

44.14 -- County Road N56 81N 33W 24 NW Fig Ave

48.41 -- State Highway 141 81N 33W 2 NW --

48.80 223 Guthrie-Carroll County line, Coon Rapids 81N 33W 3 NE --

51.98 -- County Road N44 82N 33W 27 NW Velvet Ave

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

4

5

6

7

8

9

10

11

12

13

14

15

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Middle Raccoon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 70. Middle Raccoon River, beginning at mouth in Dallas County.
SUPPLEMENTAL DATA 123

55.22 -- Twilight Avenue 82N 33W 17 SW Twilight Ave

58.39 200 295th Street 82N 34W 12 SW 295th St

63.55 -- 260th Street 83N 34W 26 NW 260th St

68.63 138 215th Street (05483360, low) 84N 34W 35 SE 215th St

72.24 74.3 County Road N33 (05483350, low) 84N 34W 29 SE Olympic Ave

76.56 56.0 U.S. Highway 71, Carroll 84N 35W 26 NE Lincoln St

78.37 55.0 U.S. Highway 30, Carroll (05483345, --) 84N 35W 15 SE --

82.49 -- Hawthorn Avenue 84N 35W 5 W Hawthorn Ave

91.80 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Middle Raccoon River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 70. Middle Raccoon River, beginning at mouth in Dallas County—Continued.
124 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Middle River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 558 Mouth of Middle River 77N 22W 9 SW --

5.24 -- State Highway 5 77N 23W 11 NW --

9.31 524 160th Avenue 77N 23W 22 SW 160th Ave

13.15 -- U.S. Highways 65 and 69 77N 23W 31 NW --

14.79 503 115th Avenue (05486490, cont) 77N 24W 35 S 115th Ave

19.82 -- 70th Avenue 76N 24W 18 NW 70th Ave

23.62 451 State Highway 92, Martensdale (05486400, low) 76N 25W 21 SE --

28.80 -- Interstate 35 76N 25W 30 S --

29.40 285 Warren-Madison County line, Warren Street 76N 25W 30 W Warren St

35.36 275 Valleyview Trail 76N 26W 33 NE Valleyview Trl

40.99 265 Quail Ridge Trail 76N 27W 36 NW Quail Ridge Trl

45.29 257 Hollwell Bridge Trail 75N 27W 4 E Hollwell Bridge 

Trl

49.29 248 County Road P51 75N 27W 7 N Clark Tower Rd

53.09 -- U.S. Highway 169 75N 28W 14 NE --

57.72 -- Pammel Road, Pammel State Park 75N 28W 16 NE Pammel Rd

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Middle River

[See section "Presentation of Curves" for explanation of list elements]

Figure 71. Middle River, beginning at mouth in Warren County.
SUPPLEMENTAL DATA 125

60.87 -- Harmon Avenue 75N 28W 17 SW Harmon Ave

66.30 -- Elderberry Avenue 75N 29W 14 SE Elderberry Ave

69.46 -- County Road P53 75N 29W 10 SW Deer Run Ave

73.06 -- State Highway 92 75N 29W 5 S --

75.10 164 Adair-Madison Avenue (05486150, low) 75N 29W 6 C Adair-Madison 

Ave

78.38 161 Madison-Adair County line 76N 29W 31 NW Adair-Madison 

Ave

84.29 -- 200th Street 76N 30W 26 NW 200th St

89.87 -- 190th Street 76N 30W 20 NE 190th St

94.77 -- County Road G27 76N 31W 12 NW 170th St

99.47 -- 145th Street 77N 31W 27 C 145th St

104.15 -- State Highway 25 77N 31W 8 SW --

107.23 -- Interstate 80 77N 32W 1 C --

108.02 72.8 Adair-Guthrie County line, 350th Street (05486100, low) 77N 32N 1 NW 350th St

109.21 -- State Highway 925 78N 32W 35 C --

113.85 30.8 320th Street 78N 32W 21 NE 320th St

127.60 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Middle River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 71. Middle River, beginning at mouth in Warren County—Continued.
126 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Mill Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 294 Mouth of Mill Creek 92N 40W 14 SE --

2.75 292 U.S. Highway 59 (06606300, low) 92N 40W 15 C --

7.38 -- High Country Road 92N 40W 4 SW High Country Rd

11.80 263 470th Street 93N 40W 32 NW 470th St

17.67 -- County Road C16 93N 41W 24 NE 450th St

24.15 179 Cherokee-OBrien County line 93N 41W 3 NE --

30.30 -- 480th Street 94N 41W 20 NW 480th St

37.20 -- State Highway 10, Paullina 94N 41W 10 NE --

41.42 -- Polk Avenue 95N 41W 32 E Polk Ave

45.39 61.6 430th Street (06606200, low) 95N 41W 29 NE 430th St

50.01 -- 410th Street 95N 41W 16 NW 410th St

54.03 -- County Road B40 95N 41W 4 NE 390th St

65.72 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

4

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mill Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 72. Mill Creek, beginning at mouth in Cherokee County.
SUPPLEMENTAL DATA 127

List of sites used to quantify main-channel slopes of Minerva Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 164 Mouth of Minerva Creek 84N 19W 2 NW --

3.96 148 County Road S62 (05451450, low) 84N 19W 5 S Hopkins Ave

8.09 69.6 155th Street (05451400, low) 85N 20W 35 C 155th St

11.57 -- Des Moines Lobe landform region boundary 85N 20W 22 NW --

12.19 61.7 County Road E18 85N 20W 15 SW Marble Rd

18.22 32.4 Marshall-Story County line 85N 20W 7 NW --

20.64 30.1 Story-Hardin County line, 100th Street 85N 21W 2 N 100th St

24.72 18.2 U.S. Highway 65 86N 21W 28 W --

36.40 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Minerva Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 73. Minerva Creek, beginning at mouth in Marshall County.
128 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Mosquito Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 113 Mouth of Mosquito Creek 79N 29W 34 SE --

0.32 -- Des Moines Lobe landform region boundary 79N 29W 34 NE --

2.03 110 280th Street (05483640, low) 79N 29W 27 NE 280th St

4.80 -- D Avenue 79N 29W 15 W D Ave

9.70 74.5 State Highway 44 79N 29W 5 NW --

13.46 67.4 220th Street (05483620, low) 80N 29W 20 S 220th St

16.84 -- 200th Street 80N 29W 17 NW 200th St

22.04 58.3 Dallas-Guthrie County line 80N 29W 6 NW --

26.96 45.7 Victory Avenue 81N 30W 27 NW Victory Ave

31.94 -- State Highway 4 81N 30W 17 N --

33.98 -- State Highway 141 81N 30W 7 N --

38.97 -- State Highway 141 81N 31W 4 SE --

44.68 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

4

6

8

10

12

14

16

18

20

22

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mosquito Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 74. Mosquito Creek, beginning at mouth in Dallas County.
SUPPLEMENTAL DATA 129

List of sites used to quantify main-channel slopes of Mosquito Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 267 Mouth of Mosquito Creek 74N 43W 30 SW --

2.96 -- Interstate 29, Council Bluffs 74N 43W 18 NE --

3.48 230 State Highway 92, Council Bluffs 74N 43W 7 SE Omaha Bridge Rd

5.15 -- Interstate 80, Council Bluffs 74N 43W 5 NW --

7.06 211 College Road, Council Bluffs (06610650, low) 75N 43W 29 E College Road

7.84 -- U.S. Highway 6, Council Bluffs 75N 43W 20 SE Kanesville Blvd

11.93 201 State Highway 191 75N 43W 2 SW --

13.18 -- State Highway 191 75N 43W 2 NE --

16.02 173 Juniper Road 76N 43W 29 SW Juniper Rd

19.26 161 Third Street, Underwood 76N 42W 16 NE Third St

24.64 131 State Highway 244, Neola (06610600, csg) 77N 42W 25 NE --

25.50 128 State Highway 191, Neola 77N 41W 19 SW Front St

26.68 -- State Highway 191 77N 41W 18 SW --

29.11 -- Interstate 680 77N 41W 5 W --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mosquito Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 75. Mosquito Creek, beginning at mouth in Pottawattamie County.
130 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

29.68 114 Pottawattamie-Harrison County line 77N 41W 5 NW --

31.93 108 325th Street 78N 41W 29 NE 325th St

36.92 80.8 Harrison-Shelby County line, 280th Street 78N 41W 3 NW 280th St

40.77 63.9 State Highway 44, Portsmouth (06610550, low) 79N 40W 16 SW --

45.32 -- 1380th Street 80N 40W 35 NW 1380th St

49.73 32.0 Discontinued USGS gage (06610520, cont) 80N 40W 11 SE --

49.99 -- State Highway 191 80N 40W 11 NE --

62.51 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of Mosquito Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 75. Mosquito Creek, beginning at mouth in Pottawattamie County—Continued.
SUPPLEMENTAL DATA 131

List of sites used to quantify main-channel slopes of Mud Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 138 Mouth of Mud Creek 98N 46W 26 NW --

0.78 138 250th Street (06483330, low) 98N 46W 27 NE 250th St

2.36 129 County Road A42 (06483325, --) 98N 46W 22 NW 240th St

4.69 126 230th Street 98N 46W 16 NE 230th St

8.22 111 County Road A34, Alvord 98N 46W 5 NE 210th St

10.98 101 190th Street 99N 46W 29 NW 190th St

13.98 -- 170th Street 99N 46W 18 NE 170th St

17.20 -- State Highway 9, Lester 99N 47W 1 NE --

18.66 63.7 County Road A18 (06483320, low) 100N 47W 36 NW 140th St

23.99 40.0 County Road K30 100N 47W 13 NW 110th St

25.28 -- Iowa-Minnesota State line 100N 47W 12 N --

42.47 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mud Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 76. Mud Creek, beginning at mouth in Lyon County.
132 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Mud Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 105 Mouth of Mud Creek 78N 2W 10 SE --

1.79 102 U.S. Highway 6 and State Highway 38 (05464900, low) 78N 2W 12 NW --

5.09 -- County Road Y14 78N 1W 5 SW Taylor St

9.54 -- Muscatine-Cedar County line 78N 1W 3 NE --

11.31 -- Cedar-Muscatine County line 78N 1W 2 NE --

16.36 -- Muscatine-Scott County line, State Hwy 927 78N 1E 5 NW --

18.65 -- Scott-Muscatine County line, State Hwy 927 78N 1E 4 NW --

23.13 8.3 Muscatine-Scott County line, Walcott 78N 1E 1 NE --

27.89 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

3

4

5

6

7

8

9

10

11

12

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mud Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 77. Mud Creek, beginning at mouth in Muscatine County.
SUPPLEMENTAL DATA 133

List of sites used to quantify main-channel slopes of Mud Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 128 Mouth of Mud Creek 80N 2E 12 NW --

1.72 119 River Camp Road (05421870, qw) 80N 2E 14 NE River Camp Rd

4.79 115 90th Avenue 80N 2E 21 SE 90th Ave

7.48 109 75th Avenue (05421850, low) 80N 2E 29 SW 75th Ave

10.25 -- State Highway 130 79N 1E 1 SE --

13.00 -- 35th Avenue 79N 1E 10 N 35th Ave

21.91 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Mud Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 78. Mud Creek, beginning at mouth in Scott County.
134 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Nishnabotna and West Nishnabotna Rivers—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 2,819 Iowa-Missouri State line 67N 42W 35 NW --

1.33 -- U.S. Highway 275, Hamburg 67N 42W 22 SE --

3.84 2,806 USGS gage (06810000, cont) 67N 42W 11 SE --

5.45 1,649 Mouth of West Nishnabotna River 67N 42W 2 NE --

8.19 1,645 County Road J46 (06808820, --) 68N 41W 19 SW 250th St

12.60 -- State Highway 2 69N 41W 29 SW --

16.15 -- County Road J26 69N 41W 8 NW 170th St

21.42 1,326 State Highway 184, Randolph (06808500, cont) 70N 41W 17 NE --

23.44 1,281 Fremont-Mills County line, Waubonsie Avenue 70N 41W 5 NE Waubonsie Ave

27.68 974 County Road L68 (06807550, low) 71N 41W 15 NW 330th St

30.25 967 Marh Avenue (06807500, cont) 71N 41W 2 NW Marh Ave

34.22 -- U.S. Highway 34 72N 41W 24 NW --

38.91 -- County Road M16 73N 40W 30 SE 370th St

44.71 -- County Road H12 73N 40W 10 NW Brothers Ave

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120

4

5

6

7

8

9

10

11

12

13

14

15

16

West Nishnabotna River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

Nishnabotna River

List of sites used to quantify main-channel slopes of the Nishnabotna and West Nishnabotna Rivers

[See section "Presentation of Curves" for explanation of list elements]

Figure 79. Nishnabotna and West Nishnabotna Rivers, beginning at Iowa-Missouri State line 

in Fremont County.
SUPPLEMENTAL DATA 135

46.20 695 Mills-Pottawattamie County line 73N 40W 3 NW --

49.53 -- County Road G66 74N 40W 21 SE Pioneer Trail

52.96 -- State Highway 92, Carson 74N 40W 10 NE --

57.59 -- U.S. Highway 6 75N 40W 23 NE --

59.40 -- County Road G42, Oakland 75N 40W 11 SE Oakland Ave

65.57 609 County Road G30, Hancock (06807410, cont) 76N 39W 18 NE Mahogany Rd

73.16 357 State Highway 83, Avoca (06807340, low) 77N 39W 17 NE --

75.94 -- Interstate 80 77N 39W 5 SE --

76.51 350 Pottawattamie-Shelby County line 77N 39W 5 NE --

81.42 -- U.S. Highway 59 78N 39W 9 SE --

87.57 316 State Highway 44, Harlan (06807320, cont) 79N 38W 19 NE Chatburn Ave

92.84 -- 1400th Street 80N 38W 33 NE 1400th St

97.17 140 1800th Street 80N 38W 10 NW 1800th St

101.19 -- County Road F24, Irwin 81N 37W 31 NE 2000th St

105.18 80.6 2200th Street 81N 37W 21 NE 2200th St

109.33 70.6 Shelby-Crawford County line, 2500th Street 81N 37W 2 NE 2500th St

111.03 63.4 Crawford-Carroll County line, Aspen Avenue 82N 37W 36 NE Aspen Ave

111.50 58.6 County Road E67 (06807260, low) 82N 36W 31 NW 330th St

114.00 43.4 State Highway 141, Manning 82N 36W 20 NW 6th St

119.14 -- 280th Street 82N 36W 3 NW 280th St

127.90 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Nishnabotna and West Nishnabotna Rivers—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 79. Nishnabotna and West Nishnabotna Rivers, beginning at Iowa-Missouri State line 

in Fremont County—Continued.
136 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Nodaway and West Nodaway Rivers—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,182 Iowa-Missouri State line, Braddyville 67N 36W 31 NW --

2.93 1,135 Abandoned bridge, between 294th and 295th Lanes 

(06817200, low)

67N 36W 18 C --

6.09 -- County Road J53, Shambaugh 68N 36W 31 W 265th St

11.51 -- State Highway 2, Clarinda 69N 36W 32 SE --

12.00 762 210th Street, Clarinda (06817000, cont) 69N 36W 32 NE 210th St

20.17 -- County Road J20, Hepburn 70N 36W 20 SE 137th St

24.03 689 Page-Montgomery County line 71N 36W 33 SW --

25.66 344 County Road H54, Villisca (06816550, low) 71N 36W 28 C --

26.33 342 Burlington Northern Santa Fe Railroad, Villisca 

(06816500, cont)

71N 36W 21 SW --

29.82 -- U.S. Highway 34 71N 36W 4 SE --

32.47 -- County Road H34 72N 36W 28 N 200 St

37.33 -- County Road H24 73N 36W 33 C 155 St

44.29 -- U.S. Highway 71, Grant 73N 36W 9 NE --

48.16 -- Montgomery-Cass County line 73N 36W 2 NW --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Nodaway River West Nodaway River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Nodaway and West Nodaway Rivers

[See section "Presentation of Curves" for explanation of list elements]

Figure 80. Nodaway and West Nodaway Rivers, beginning at Iowa-Missouri State line 

in Page County.
SUPPLEMENTAL DATA 137

51.74 -- County Road C66 74N 35W 31 N Yankton Rd

58.12 65.1 County Road N28 (06816300, low) 74N 35W 15 SW 690th St

62.94 -- County Road G53 74N 34W 6 SW Tuscon Rd

66.78 23.4 State Highway 148 (06816290, csg) 75N 34W 33 SE --

78.17 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Nodaway and West Nodaway Rivers—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 80. Nodaway and West Nodaway Rivers, beginning at Iowa-Missouri State line in Page 

County—Continued.
138 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of North Cedar Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 127 Mouth of North Cedar Creek 74N 18W 15 N --

3.28 -- State Highway 5 74N 18W 20 NE --

9.80 111 170th Place (05488900, low) 74N 19W 26 S 170th Pl

14.69 62.3 Marion-Monroe County line 74N 19W 33 S --

15.33 61.3 County Road H16 (05488800, low) 73N 19W 4 NE 105th St

20.13 43.2 Monroe-Lucas County line 73N 19W 18 SW --

23.79 -- County Road 73N 20W 27 NE --

28.27 21.5 County Road 72N 20W 5 NW --

37.65 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of North Cedar Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 81. North Cedar Creek, beginning at mouth in Marion County.
SUPPLEMENTAL DATA 139

List of sites used to quantify main-channel slopes of North Fork Black Hawk Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 119 Mouth of North Fork Black Hawk Creek 87N 15W 1 SE --

2.23 107 County Road D35 88N 15W 35 E 215th Ave

5.52 -- County Road D25 88N 15W 24 NW 190th St

7.72 -- County Road T65 88N 15W 11 SW X Ave

12.15 76.3 Usher Avenue, Dike (05463400, low) 88N 15W 8 N Usher Ave

15.95 -- U.S. Highway 20 88N 16W 1 NE --

25.09 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

4

5

6

7

8

9

10

11

12

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of North Fork Black Hawk Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 82. North Fork Black Hawk Creek, beginning at mouth in Grundy County.
140 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the North Fork Maquoketa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 592 Mouth of North Fork Maquoketa River 84N 2E 13 NE --

0.27 592 Rockdale Road (05418470, --) 84N 2E 13 NE Rockdale Rd

5.93 -- 212th Avenue 85N 3E 30 SE 212th Ave

8.24 516 U.S. Highway 61, Fulton (05418450, cont) 85N 2E 25 NE --

12.37 505 County Road E17 (05418400, cont) 85N 2E 16 SE 150th St

16.94 -- 109th Avenue 85N 2E 7 SE 109th Ave

22.12 358 60th Avenue 85N 1E 10 SW 60th Ave

29.40 343 Jackson-Jones County line 86N 1E 31 NW --

44.24 207 Jones-Dubuque County line 86N 1W 6 NW --

44.58 -- U.S. Highway 151, Cascade 87N 1W 31 SW 1st Ave W

47.50 196 State Highway 136 (05418150, --) 87N 2W 26 NW --

57.30 168 Delaware-Dubuque County line 87N 2W 18 SW --

62.33 158 Dubuque-Delaware County line 87N 2W 6W --

63.90 152 County Road D35 (05418120, --) 88N 3W 36 NE 272nd St

69.41 125 Delaware-Dubuque County line 88N 3W 12 E --

71.52 122 U.S. Highway 20, Dyersville (05418110, --) 88N 2W 6 NW --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

4

5

6

7

8

9

10

11

12

13

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the North Fork Maquoketa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 83. North Fork Maquoketa River, beginning at mouth in Jackson County.
SUPPLEMENTAL DATA 141

72.57 80.2 1st Avenue West, Dyersville (05418100, low) 89N 2W 31 NW 1st Ave W

79.15 36.0 Vaske Road 89N 2W 7 W Vaske Rd

80.67 28.6 State Highway 136, New Vienna 89N 2W 5 SW Columbus St

96.61 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the North Fork Maquoketa River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 83. North Fork Maquoketa River, beginning at mouth in Jackson County—Continued.
142 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the North River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 400 Mouth of North River 78N 23W 36 SE --

4.06 -- Polk-Warren County line, Carlisle 78N 23W 34 SW --

4.98 -- State Highway 5 77N 23W 4 N --

9.03 387 U.S. Highways 65 and 69 77N 24W 12 SE --

15.99 -- 100th Avenue 77N 24W 22 NW 100th Ave

22.83 349 County Road R57 (05486000, cont) 77N 24W 20 SW Hwy R57

26.27 -- State Highway 28 77N 25W 25 N --

31.53 -- County Road R45 77N 25W 34 NW 43rd Ave

36.60 -- Interstate 35 76N 25W 6 C --

37.44 265 Warren-Madison County line, County Road R35 76N 25W 6 NW 10th Ave

40.61 -- Windwood Trail 76N 26W 11 NW Windwood Trl

45.81 -- Upland Trail 76N 26W 9 NW Upland Trl

50.50 203 County Road R16 (05485900, low) 77N 27W 36 NW Quail Ridge Ave

53.96 -- McBride Trail 76N 27W 3 NE McBride Trl

59.77 116 U.S. Highway 169 76N 28W 12 NE --

65.67 102 Ironwood Trail 76N 28W 10 SW Ironwood Trl

Figure 84. North River, beginning at mouth in Polk County.

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

5

6

7

8

9

10

11

12

13

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the North River

[See section "Presentation of Curves" for explanation of list elements]
SUPPLEMENTAL DATA 143

71.73 -- County Road P57 76N 29W 12 SW Earlham Rd

78.66 68.9 County Road P53 (05485700, low) 76N 29W 9 NE Pitzer Rd

85.01 55.9 Madison-Adair County line 77N 29W 31 SW Adair-Madison 

Ave

90.78 26.4 County Road P28 77N 30W 28 SW Stuart Rd

95.65 17.5 Sheldon Avenue 77N 30W 18 SW Sheldon Ave

106.62 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the North River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 84. North River, beginning at mouth in Polk County—Continued.
144 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the North Skunk River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 869 Mouth of North Skunk River 74N 10W 5 NE --

3.62 -- County Road V57 75N 10W 30 SW 280th Ave

7.55 -- 265th Avenue 75N 11W 26 NW 265th Ave

19.60 730 State Highway 149 (05472500, cont) 75N 12W 14 SE --

25.66 -- 180th Avenue 75N 12W 21 SW 180th Ave

33.80 621 State Highway 21 75N 13W 14 NW --

40.34 606 Keokuk-Mahaska County line 75N 13W 6 SW --

41.28 -- State Highway 92 75N 14W 1 NE --

48.13 529 185th Street 76N 14W 15 SE 185th St

53.61 -- County Road V13 77N 14W 33 SW Urbana Ave

57.27 -- Snyder Avenue 77N 14W 30 NE Snyder Ave

63.44 443 County Road T65 (05472350, --) 77N 15W 22 NE Parkin Ave

65.61 -- U.S. Highway 63 77N 15W 16 SE --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the North Skunk River

[See section "Presentation of Curves" for explanation of list elements]

Figure 85. North Skunk River, beginning at mouth in Keokuk County.
SUPPLEMENTAL DATA 145

72.72 384 Mahaska-Poweshiek County line, State Highway 146 77N 16W 1 N --

76.49 358 40th Street (05472300, low) 78N 16W 27 SW 40th St

80.84 287 Poweshiek-Jasper County line 78N 16W 18 W --

82.01 -- State Highway 225 78N 17W 12 C --

86.34 250 South 68th Avenue East 79N 17W 34 N S 68th Ave E

92.27 180 South 12th Avenue East (05472200, --) 79N 17W 5 NW S 12th Ave E

92.72 -- Interstate 80 80N 17W 31 SE --

93.76 -- U.S. Highway 6 80N 17W 30 SW --

95.07 -- State Highway 224, Kellogg 80N 18W 25 SW East St

99.28 122 East 76th Street North 80N 18W 9 SW E 76th St N

104.09 101 Clay Street (05472100, low) 81N 19W 35 NW Clay St

106.64 52.5 State Highway 14 81N 19W 22 NW --

106.95 52.2 County Road F17 (05472090, csg) 81N 19W 21 NE Hwy 223 W

112.03 36.8 Jasper-Marshall County line, North 115th Avenue West 81N 19W 6 NW N 115th Ave W

118.04 -- State Highway 330 82N 20W 14NW --

125.21 -- Des Moines Lobe landform region boundary 83N 20W 20 NE --

129.65 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the North Skunk River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 85. North Skunk River, beginning at mouth in Keokuk County—Continued.
146 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Ocheyedan River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 434 Mouth of Ocheyedan River, Spencer 96N 37W 13 NE --

4.88 426 County Road M38 (06605000, cont) 96N 37W 15 SW 190th Ave

8.37 417 350th Street 96N 37W 18 NE 350th St

12.87 300 County Road M27 96N 38W 10 W 130th Ave

16.83 -- U.S. Highway 18 97N 38W 31 NE --

20.34 249 Clay-O’Brien County line 97N 38W 7 SW --

22.94 229 O’Brien-Osceola County line 98N 39W 35 SW --

24.32 226 260th Street (06604700, low) 98N 39W 34 NW 260th St

28.25 160 County Road M12, May City 98N 39W 8 SW 230th St

32.84 121 County Road A30 99N 40W 35 NE 200th St

34.61 -- Hydrologic Regions 1 and 2, and Des Moines Lobe 

landform region boundaries

99N 40W 23 SW --

36.67 99.2 County Road A22 99N 40W 16 NE 170th St

40.98 73.5 State Highway 9 (06604510, csg) 99N 40W 6 NE --

68.29 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

5.0

5.2

5.4

5.6

5.8

6.0

6.2

6.4

6.6

6.8

7.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Ocheyedan River

[See section "Presentation of Curves" for explanation of list elements]

Figure 86. Ocheyedan River, beginning at mouth in Clay County.
SUPPLEMENTAL DATA 147

List of sites used to quantify main-channel slopes of Old Mans Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 248 Mouth of Old Mans Creek 78N 6W 27 NE --

1.10 247 State Highway 923 (05455130, --) 78N 6W 21 SE --

1.34 -- U.S. Highway 218 78N 6W 21 SE --

3.14 219 County Road F62 (05455120, --) 78N 6W 16 W 500th St

8.83 201 County Road W62 (05455100, cont) 79N 7W 36 W Sharon Center Rd

12.17 180 State Highway 1 79N 7W 33 SE --

15.82 136 Hazelwood Road 79N 7W 31 SW Hazelwood Rd

22.51 -- Calkins Avenue 79N 8W 33 SW Calkins Ave

25.71 119 Johnson-Iowa County line 79N 8W 31 SW --

28.28 -- W Avenue 79N 9W 34 E W Ave

32.32 81.2 SS Avenue (05455050, low) 79N 9W 31 SW SS Ave

36.35 66.9 265th Street 79N 10W 27 E 265th St

39.81 -- State Highway 149, Williamsburg 79N 10W 10 W Highland St

43.09 23.1 County Road V66 79N 10W 6 SW M Ave

53.09 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Old Mans Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 87. Old Mans Creek, beginning at mouth in Johnson County.
148 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Otter Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 107 Mouth of Otter Creek 89N 9W 19 SW --

4.63 101 Abandoned bridge, 170th Street (05420940, low) 89N 9W 5 SW 170th St

7.82 71.1 150th Street 90N 9W 32 NE 150th St

11.36 55.7 125th Street 90N 9W 16 SE 125th St

14.78 41.3 Buchanan-Fayette County line, State Highway 281 90N 9W 4 N --

18.99 32.6 40th Street 91N 9W 18 SW 40th St

28.98 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Otter Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 88. Otter Creek, beginning at mouth in Buchanan County.
SUPPLEMENTAL DATA 149

List of sites used to quantify main-channel slopes of Otter Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 210 Mouth of Otter Creek 98N 44W 21 NW --

1.71 208 250th Street (06483480, low) 98N 44W 28 NW 250th St

5.97 194 Lyon-Sioux County line, 270th Street 98N 44W 35 SW 270th St

7.68 -- County Road B14 97N 44W 1 SE 280th St

12.37 -- Sioux-Lyon County line 97N 43W 5 NE --

15.03 129 Lily Street (06483470, low) 98N 43W 34 NW Lily St

20.07 120 Lyon-Osceola County line, County Road L26 98N 43W 36 SE McKinley St

23.90 107 County Road A52 98N 42W 27 NW 250th St

26.89 -- State Highway 60, Ashton 98N 42W 10 SE --

29.78 88.0 County Roads A34 and L36 (06483460, csg) 98N 42W 1 SW Olive St

35.25 -- Oriole Street 99N 42W 25 NE Oriole St

38.64 -- State Highway 60, Sibley 99N 42W 13 S --

40.35 29.9 County Road A22 (06483430, csg) 99N 42W 14 NE 170th St

45.35 -- State Highway 9 99N 42W 3 N --

63.35 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Otter Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 89. Otter Creek, beginning at mouth in Lyon County.
150 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Otter Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 168 Mouth of Otter Creek 76N 23W 34 SW --

4.79 155 State Highway 205 (05487450, low) 75N 23W 22 NE --

7.01 138 U.S. Highway 65 75N 23W 34 NW --

12.17 114 Truman Street 74N 23W 17 SW Truman St

18.27 104 Warren-Lucas County line, County road 74N 23W 32 SW --

19.64 102 County Road (05487400, low) 73N 23W 5 S --

23.17 46.5 Lucas-Clarke County line 73N 23W 6 SW --

28.09 -- 310th Avenue 73N 24W 15 SW 310th Ave

30.00 -- Pacific Street 73N 24W 17 SW Pacific St

41.37 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

6

7

8

9

10

11

12

13

14

15

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Otter Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 90. Otter Creek, beginning at mouth in Warren County.
SUPPLEMENTAL DATA 151

List of sites used to quantify main-channel slopes of Pigeon Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 165 Mouth of Pigeon Creek 75N 44W 3 SE --

0.91 163 River Road North (06609950, low) 75N 44W 3 NE River Road N

1.39 -- Interstate 29 76N 44W 34 SE --

3.12 -- State Highway 988 76N 44W 27 NE --

7.23 -- State Highway 183 76N 43W 6 SW --

11.04 -- 210th Street 77N 43W 27 NW 210th St

16.27 66.6 County Road G14 (06609900, low) 77N 42W 17 NW Westgate Rd

18.43 -- Interstate 680 77N 42W 4 C --

19.10 56.5 Pottawattamie-Harrison County line 77N 42W 4 NE --

23.14 -- 305th Trail 78N 42W 15 NE 305th Trl

26.59 -- Taylor Avenue 78N 42W 2 NE Taylor Ave

30.49 -- State Highway 44 79N 41W 22 N --

33.59 -- 230th Street 79N 41W 11 NE 230th St

44.08 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

9

10

11

12

13

14

15

16

17

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Pigeon Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 91. Pigeon Creek, beginning at mouth in Pottawattamie County.
152 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Platte River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 282 Iowa-Missouri State line 67N 32W 28 SW Missouri-Taylor St

4.19 -- County Road J55, Blockton 67N 32W 12 C North St

6.75 255 Taylor-Ringgold County line, County Road P14 68N 32W 36 NE --

10.37 247 County Road J43, Maloy 68N 31W 21 E Co Rd N

13.04 236 State Highway 2 68N 31W 10 N --

17.36 217 County road (06818750, cont) 69N 31W 22 NW --

20.45 211 County Road J23 69N 31W 3 NW --

24.80 179 County road (06818700, low) 70N 31W 16 NW --

28.92 103 Ringgold-Union County line, County Road J13 70N 31W 6 NE --

32.57 92.1 Union-Adams County line, State Highway 25 71N 31W 19 SW --

34.09 77.9 County Road H45 (06818600, low) 71N 32W 13 SW 250th St

38.40 51.7 U.S. Highway 34 (06818598, csg) 71N 32W 2 E --

40.40 36.1 Adams-Union County line 72N 32W 36 NE Adams-Union Ave

44.00 28.1 190th Street 72N 31W 21 NE 190th St

55.55 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Platte River

[See section "Presentation of Curves" for explanation of list elements]

Figure 92. Platte River, beginning at Iowa-Missouri State line in Taylor County.
SUPPLEMENTAL DATA 153

List of sites used to quantify main-channel slopes of Prairie Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 216 Mouth of Prairie Creek, Cedar Rapids 83N 7W 34 SE --

2.59 -- Interstate 380, Cedar Rapids 82N 7W 4 SW --

3.18 208 6th Street, Cedar Rapids (05464650, low) 82N 7W 9 NW --

5.16 -- U.S. Highway 30, Cedar Rapids 82N 7W 6 SE Lincoln Freeway

7.22 196 Old Bridge Road 82N 8W 12 SW Old Bridge Rd

10.51 178 U.S. Highway 151, Fairfax (05464640, cont) 82N 8W 9 SW Williams Blvd

13.94 171 Linn-Benton County line 82N 8W 7 SW Linn Benton Rd

17.24 -- 32nd Avenue 82N 9W 14 SE 32nd Ave

22.03 126 28th Avenue (05464600, low) 82N 9W 30 NW 28th Ave

28.07 -- County Road E66 (05464580, qw) 82N 10W 20 NW 77th Ave

30.31 87.0 State Highway 82, Blairstown (05464560, csg) 82N 11W 13 SW Locust St

34.81 64.2 County Road E58 (05464550, low) 82N 11W 9 NE 75th St

37.32 -- U.S. Highway 30 83N 11W 32 NE --

41.67 -- 5th Avenue, Keystone 83N 12W 14 SW 5th Ave

48.41 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

4

5

6

7

8

9

10

11

12

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Prairie Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 93. Prairie Creek, beginning at mouth in Linn County.
154 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Raccoon and North Raccoon Rivers—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 3,629 Mouth of Raccoon River, Des Moines 78N 24W 10 NW --

2.56 3,625 Fleur Drive, Des Moines (05484900, cont) 78N 24W 8 NE Fleur Dr

8.60 3,529 State Highway 28, Des Moines (05484650, cont) 78N 25W 14 NE 63rd St

13.95 -- Interstate 35, West Des Moines 78N 25W 30 SE --

15.66 3,498 Polk-Dallas County line 78N 25W 30 NW --

24.38 -- County Road F90, Booneville 78N 26W 30 SE 360th St

29.32 3,441 County Road R16, Van Meter (05484500, cont) 78N 27W 22 SW Richland Rd

30.46 2,298 Mouth of North Raccoon River 78N 27W 21 NW --

30.55 -- Interstate 80 78N 27W 21 NW --

30.56 -- Des Moines Lobe landform region boundary 78N 27W 21 NW --

39.84 2,281 U.S. Highway 6, Adel (05483305, --) 79N 27W 32 NE --

44.07 -- U.S. Highway 169 79N 27W 20 SW --

49.70 2,242 State Highway 44 79N 27W 6 NE --

54.87 2,229 County Road F31 80N 28W 13 NE Minburn Rd

60.26 -- County Road P58 81N 28W 34 NW J Ave

64.49 2,169 State Highway 141 (05483300, qw) 81N 28W 8 C --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 20 40 60 80 100 120 140 160 180 200 220

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Raccon River North Raccon River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Raccoon and North Raccoon Rivers

[See section "Presentation of Curves" for explanation of list elements]

Figure 94. Raccoon and North Raccoon Rivers, beginning at mouth of Raccoon River in 

Polk County.
SUPPLEMENTAL DATA 155

69.14 -- Between Dallas-Greene/Greene-Dallas Co. lines 82N 29W 36 SE --

73.17 -- County Road P46, Dawson 81N 29W 3 SW D Ave

75.37 2,045 Dallas-Greene County line 81N 29W 5 N --

80.62 2,027 County Road E57 82N 29W 18 SW 305th

85.00 -- County Road P30 83N 30W 36 SW R Ave

92.61 1,619 State Highway 4 (05482500, cont) 83N 30W 20 NW --

96.71 1,596 County Road E53 83N 31W 11 SW 237th

101.60 -- U.S. Highway 30 83N 31W 4 NW --

106.89 1,552 County Road E33 84N 32W 23 SE Eaton Ave

111.53 -- County Road N65 84N 32W 10 SW D Ave

117.06 -- 175th 84N 32W 8 NW 175th

120.00 1,355 Greene-Carroll County line, County Road N58 84N 32W 18 NW A Ave

124.12 -- County Road N50 84N 33W 3 NE 162nd St

128.38 1,256 County Road E19 85N 33W 21 SE Velvet Ave

131.24 1,225 State Highway 286 (05482430, qw) 85N 33W 17 SW --

135.49 1,182 Sac-Calhoun County line 85N 33W 6 N --

138.47 -- County Road N37 86N 34W 25 SW Janesville Ave

144.88 1,003 State Highway 175 (05482400, low) 86N 34W 17 E --

147.82 852 Calhoun-Sac County line, County Road N28 86N 34W 6 SW Dakota Ave

152.69 -- Xenia Avenue 86N 35W 11 NW Xenia Ave

157.10 822 Wadsley Avenue 86N 35W 4 NE Wadsley Ave

161.76 807 State Highway 196 87N 35W 29 NW --

163.44 804 Taylor Avenue (05482340, --) 87N 36W 24 SE Taylor Ave

166.37 700 County Road D46 (05482300, --) 87N 36W 13 NW 300th St

168.95 697 County Road D42 87N 36W 1 NW 280th St

169.83 -- Sierra Avenue (05482260, --) 88N 36W 36 NW Sierra Ave

172.43 349 U.S. Highway 20, Sac City 88N 36W 24 W E Main St

177.74 333 230th Street 88N 36W 11 NW 230th St

179.78 326 215th Street 89N 35W 31 SE 215th St

186.20 314 County Road D15 89N 36W 24 N 190th St

190.95 287 Sac-Buena Vista County line, 160th Street 89N 36W 1 NE 160th St

196.54 233 State Highway 7 (05482135, cont) 90N 36W 24 NW --

201.09 -- County Road C49 91N 36W 36 NW 590th St

204.82 164 560th Street (05482120, low) 91N 36W 15 NE 560th St

208.66 -- State Highway 3 92W 36W 33 N --

210.77 77.4 510th Street (05482100, low) 92N 36W 21 NE 510th St

216.56 -- County Road W50 93N 36W 34 SW 160th St

220.67 -- Hydrologic Regions 1 and 2 boundary 93N 35W 30 NW --

228.02 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Raccoon and North Raccoon Rivers—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 94. Raccoon and North Raccoon Rivers, beginning at mouth of Raccoon River 

in Polk County—Continued.
156 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Roberts Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 140 Mouth of Roberts Creek 93N 5W 25 SE --

3.39 -- State Highway 13 93N 5W 13 NW --

5.78 111 County Road X28 93N 5W 2 SE Fawn Hollow Rd

11.00 101 County Road B65, St. Olaf (05412150, low) 94N 5W 25 SW 205th St

11.22 70.7 County Road X28, St. Olaf (05412100, cont) 94N 5W 25 NW Main St

16.87 65.2 Farm field lane (05412093, qw) 94N 5W 14 SW --

17.64 64.3 County Road B60 (05412092, qw) 94N 5W 15 SE Farmersburg Rd

18.81 63.6 Essex Avenue (05412090, --) 94N 5W 15 N Essex Ave

21.10 61.8 County Road X16 (05412080, qw) 94N 5W 16 N Eagle Ave

22.50 30.4 Dolphin Avenue (05412050, qw) 94N 5W 17 NE Dolphin Ave

25.82 28.8 Dave Avenue (05412048, qw) 94N 5W 8 SW Dave Ave

27.33 26.0 172nd Street (05412046, qw) 94N 5W 7 NW 172nd St

29.17 18.2 County Road W70 (05412040, qw) 94N 6W 1 SW 165th St

41.78 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Roberts Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 95. Roberts Creek, beginning at mouth in Clayton County.
SUPPLEMENTAL DATA 157

List of sites used to quantify main-channel slopes of the Rock River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,688 Mouth of Rock River 95N 48W 1 NE --

0.67 1,688 390th Street (06483600, --) 95N 47W 6 NW 390th St

6.54 1,681 County Road B30 (06483550, --) 96N 47W 16 SE 360th St

9.21 1,673 County Road B20 96N 47W 3 SW 340th St

15.55 1,600 U.S. Highway 18 97N 47W 25 NE --

19.38 1,592 County Road K30, Rock Valley (06483500, cont) 97N 46W 16 SW Elwood Ave

26.43 1,526 Sioux-Lyon County line 97N 46W 2 NW --

27.58 1,050 County Road A52 (06483340, low) 98N 46W 35 NW 260th St

30.10 -- County Road K42 98N 46W 23 NE Garfield St

36.59 -- U.S. Highway 75 99N 45W 32 SE --

43.14 859 County Road A22 (06483300, low) 99N 45W 15 NW 170th St

44.83 853 USGS gage, Rock Rapids (06483290, cont) 99N 45W 4 SE --

46.04 851 State Highway 9 99N 45W 4 NE 1st Ave/Main St

46.49 788 Discontinued USGS gage, Rock Rapids (06483270, cont) 100N 45W 33 SW --

49.25 -- County Road A16 100N 45W 20 SE Harding St

54.06 558 Iowa-Minnesota State line (06483100, low) 100N 45W 8 NE --

147.63 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

4.0

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Rock River

[See section "Presentation of Curves" for explanation of list elements]

Figure 96. Rock River, beginning at mouth in Sioux County.
158 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Salt Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 223 Mouth of Salt Creek 82N 12W 31 SW --

0.36 -- Benton-Tama County line 82N 12W 31 W --

2.82 217 380th Street, Belle Plaine (05452020, qw) 82N 13W 25 NE 380th St

8.02 -- 340th Street 82N 13W 1 N 340th St

9.98 201 U.S. Highway 30 (05452000, cont) 83N 13W 36 NW --

15.02 167 County Road E44 83N 13W 15 N Hwy E44

18.42 85.2 V Avenue (05451930, low) 84N 13W 33 SE V Ave

22.07 49.6 County Road V18 84N 13W 29 NW Hwy V18

26.33 33.4 R Avenue 84N 14W 12 NW R Ave

30.32 22.1 PP Avenue 85N 14W 34 N PP Ave

42.09 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Salt Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 97. Salt Creek, beginning at mouth in Benton County.
SUPPLEMENTAL DATA 159

List of sites used to quantify main-channel slopes of Sevenmile Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 124 Mouth of Sevenmile Creek 73N 36W 33 NW --

0.28 124 T Avenue (06816400, low) 73N 36W 33 NW T Ave

5.56 96.3 Montgomery-Cass County line, County Road N16 73N 36W 6 NE 100th St

10.69 84.7 State Highway 92 74N 36W 7 NE --

14.33 60.8 U.S. Highway 71 and State Highway 92 (06816350, low) 75N 36W 33 SE --

18.03 -- 660th Street 75N 35W 31 SW 660th St

19.63 -- State Highway 92 75N 35W 32 NW --

23.64 36.5 County Road N28 75N 35W 15 SW 690th St

27.27 29.3 Newport Road 75N 35W 11 NE Newport Rd

30.70 -- Memphis Road 75N 34W 6 NE Memphis Rd

39.68 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Sevenmile Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 98. Sevenmile Creek, beginning at mouth in Montgomery County.
160 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Shell Rock River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,783 Mouth of Shell Rock River 90N 14W 4 C --

1.15 1,782 Black Hawk-Bremer County line, Marquis Road West 90N 14W 4 NE Marquis Rd W

3.88 -- 265th Street 91N 14W 28 NW 265th St

8.04 1,752 Bremer-Butler County line 91N 14W 18 NW --

10.73 1,746 County Road T63, Shell Rock (05462000, cont) 91N 15W 11 NE Cherry St

11.66 -- State Highway 3 91N 15W 2 SW --

20.24 -- State Highway 188, Clarksville 92N 15W 19 SW --

22.57 1,626 County Road C33, Clarksville (05461500, cont) 92N 16W 13 NW 180th St

29.51 -- County Road T47 93N 16W 27 W Packard Ave

36.80 1,357 Traer Street, Greene (05461000, cont) 93N 17W 1 SW Traer St

37.43 -- State Highway 14, Greene 93N 17W 2 NE --

38.20 -- Butler-Floyd County line 93N 17W 2 NW --

40.85 1,341 290th Street 94N 17W 28 NE 290th St

43.45 1,318 County Road B60, Marble Rock (05460500, cont) 94N 17W 8 SE Bradford St

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Shell Rock River

[See section "Presentation of Curves" for explanation of list elements]

Figure 99. Shell Rock River, beginning at mouth in Black Hawk County.
SUPPLEMENTAL DATA 161

50.64 1,267 Foothill Road 95N 18W 36 NW Foothill Rd

54.59 -- East Main Avenue, Rockford 95N 18W 11 SW E Main Ave

59.97 517 180th Street 96N 18W 33 NW 180th St

61.99 -- U.S. Highway 18 96N 18W 20 C --

65.90 499 Floyd-Cerro Gordo County line 96N 18W 7 W --

69.46 -- Hydrologic Regions 1 and 2 boundary 97N 19W 35 NE --

131.15 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Shell Rock River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 99. Shell Rock River, beginning at mouth in Black Hawk County—Continued.
162 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Silver Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 282 Mouth of Silver Creek 71N 41W 21 N --

0.54 -- Orchard Avenue (06807900, low) 71N 41W 16 SW Orchard Ave

3.27 -- County Road L63 71N 41W 5 NW 310th St

6.95 244 U.S. Highway 34 72N 41W 19 NW --

10.04 221 County Road H20 72N 42W 1 NE Gaston Ave

13.35 203 Dobney Avenue, Silver City 73N 42W 24 NW Dobney Ave

16.95 -- Mills-Pottawattamie County line 73N 41W 6 NE Applewood Ave

18.79 115 County Road L63 (06807650, low) 74N 41W 28 SW 320th St

22.98 -- State Highway 92 74N 41W 10 N --

27.28 -- U.S. Highway 6 75N 41W 24 NW --

31.53 -- Juniper Road 76N 40W 31 NE Juniper Rd

34.32 -- County Road M16 76N 40W 21 NW 380th St

37.88 59.2 Rosewood Road (06807600, low) 76N 40W 4 NE Rosewood Rd

42.18 -- State Highway 83 77N 40W 15 NW --

44.18 -- Interstate 80 77N 40W 3 W --

44.81 41.2 Pottawattamie-Shelby County line 77N 40W 3 NW --

48.57 25.5 400th Street 78N 40W 23 NE 400th St

65.66 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Silver Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 100. Silver Creek, beginning at mouth in Mills County.
SUPPLEMENTAL DATA 163

List of sites used to quantify main-channel slopes of Sixmile Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 108 Mouth of Sixmile Creek 94N 48W 28 C --

0.86 -- State Highway 12 94N 48W 28 SE --

2.68 104 Birch Avenue (06484150, low) 94N 48W 26 SW Birch Ave

8.27 -- County Road B58 94N 48W 12 SW 470th St

11.78 -- State Highway 10 94N 47W 5 NW --

15.69 68.8 430th Street (06484100, low) 95N 47W 28 NW 430th St

22.31 48.6 Dove Avenue 95N 46W 19 SW Dove Ave

26.86 26.3 Elwood Avenue 95N 46W 9 SW Elwood Ave

30.34 18.6 County Road B40 95N 46W 3 N 390th St

38.13 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Sixmile Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 101. Sixmile Creek, beginning at mouth in Sioux County.
164 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Skunk and South Skunk Rivers—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 4,355 Mouth of Skunk River 68N 2W 8 S --

6.15 4,334 U.S. Highway 61 69N 3W 33 SW --

10.41 4,303 County Road X38, Augusta (05474000, cont) 69N 4W 26 NE Main Rd

17.00 4,281 280th Avenue 69N 4W 7 NW 280th Ave

19.86 4,258 Lee-Des Moines-Henry County line 69N 5 W 2 NW --

21.81 4,231 County Road X23, Lowell 70N 5W 28 SE New London Rd

27.65 4,047 County Road W75 70N 6W 25 NW Lexington Ave

32.94 4,013 U.S. Highway 218 (05473430, --) 70N 6W 4 NE --

37.82 4,001 County Road W55, Oakland Mills (05473420, --) 71N 7W 24 SW Franklin Ave

42.84 3,425 U.S. Highway 34, Rome 71N 7W 4 SW --

44.91 3,422 Old Highway 34 (05473330, --) 71N 7W 3 NW Old Highway 34

48.02 3,398 White Oak Road 72N 7W 32 NE White Oak Rd

53.04 3,356 Henry-Jefferson County line 72N 7W 18 NW --

57.61 3,237 County Road H28 73N 8W 36 NE 146th Blvd

64.41 2,916 State Highway 78, Coppock (05473000, cont) 73N 8W 1 NE --

64.57 2,916 Jefferson-Washington County line 73N 8W 1 NE --

72.33 2,884 State Highway 1 (05472700, --) 74N 8W 20 SW --

80.20 2,854 County Road W21 74N 9W 10 SW Dogwood Ave

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 20 40 60 80 100 120 140 160 180 200 220 240

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Skunk River South Skunk River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Skunk and South Skunk Rivers

[See section "Presentation of Curves" for explanation of list elements]

Figure 102. Skunk and South Skunk Rivers, beginning at mouth of Skunk River at Lee-Des Moines 

County line.
SUPPLEMENTAL DATA 165

84.83 2,750 Washington-Keokuk County line 74N 9W 6 SW --

88.93 2,741 County Road W15 (05472540, --) 74N 10W 2 NE 323rd Ave

94.72 2,709 Confluence of North and South Skunk Rivers 74N 10W 5 NE --

98.96 1,837 County Road V67 (05472040, --) 74N 10W 6 SW 280th Ave

101.91 1,806 County Road V5G 74N 11W 3 SE Co Rd V5G S

108.75 -- 290th St 74N 12W 1 SE 290th St

111.87 1,786 State Highway 149 (05472030, --) 74N 12W 2 SW --

116.88 -- 180th Avenue 74N 12W 5 SE 180th Ave

125.25 1,740 State Highway 21 75N 13W 34 N --

129.94 1,718 Keokuk-Mahaska County line 75N 13W 30 SW --

134.33 1,697 County Road V13 75N 14W 15 SW Ventura Ave

137.07 1,687 State Highway 92 (05472010, qw) 75N 14W 7 SE --

142.23 1,652 County Road T65 76N 15W 33 SW Oxford Ave

145.86 1,635 U.S. Highway 63 (05471500, cont) 76N 16W 25 SW --

152.46 1,599 County Road T43 76N 17W 12 SE Fisher Ave

157.20 1,539 State Highway 102 77N 17W 28 SE --

160.76 1,440 Mahaska-Marion County line 77N 17W 19 NW --

165.64 -- County Road T14 77N 18W 3 SE Hwy T14

168.16 1,407 Marion-Jasper County line 77N 18W 5 NW --

172.37 -- County Road S74 78N 19W 23 SW Red Bridge Rd

175.01 1,363 County Road F62, Reasnor (05471390, --) 78N 19W 10 NW Hwy F-62 E

179.41 1,281 State Highway 14 (05471380, --) 79N 19W 29 NW --

183.27 1,260 Neptune Street 79N 20W 14 NW Neptune St

189.78 803 State Highway 117, Colfax (05471050, cont) 79N 21W 1 SW --

192.24 -- Interstate 80 79N 21W 4 NE --

195.94 748 Jasper-Polk County line 80N 21W 30 NW --

198.92 722 U.S. Highway 65 80N 22W 15 NE --

204.03 688 County Roads F22 and S14 81N 22W 30 SW NE Yodder Dr

209.50 649 Polk-Story County line 81N 23W 3 NE --

210.54 -- State Highway 210 82N 23W 34 NE --

211.73 615 320th Street, Cambridge (05471020, --) 82N 23W 27 NW 320th St

216.21 585 280th Street (05471008, --) 82N 23W 5 NW 280th St

218.06 -- Interstate 35 83N 23W 30 SE --

218.57 -- County Road E57 (05471006, --) 83N 23W 30 NW 265th St

219.81 -- East end of Ken Maril Road (05471004, --) 83N 24W 24 E --

221.66 556 U.S. Highway 30, Ames (05471000, cont) 83N 24W 13 NW --

223.01 329 Lincoln Way, Ames (05470190, --) 83N 24W 12 NW Lincoln Way

227.42 315 USGS gage, Ames (05470000, cont) 84N 24W 23 SW --

230.62 -- 180th Street (05469995, qw) 84N 24W 12 SE 180th St

231.04 -- Hydrologic Regions 1 and 2 boundary 84N 23W 7 SW --

232.22 222 170th Street (05469980, qw) 84N 23W 7 N 170th St

276.88 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Skunk and South Skunk Rivers—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 102. Skunk and South Skunk Rivers, beginning at mouth of Skunk River at Lee-Des Moines 

County line—Continued.
166 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Soap Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 253 Mouth of Soap Creek 71N 12W 35 SW --

1.17 -- Wapello-Davis County line 71N 12W 34 SW --

2.91 243 Tulip Avenue (05490100, low) 70N 12W 5 C Tulip Ave

5.60 -- County Road J15 70N 12W 7 NW Floris Ave

11.28 191 Peach Avenue 70N 13W 15 NW Peach Ave

17.34 -- U.S. Highway 63 70N 14W 12 NE --

22.08 -- Jewell Avenue 70N 14W 10 SW Jewell Ave

26.35 136 Hill Boulevard 70N 14W 19 NE Hill Blvd

31.84 97.3 Clay Avenue (05489900, low) 70N 15W 21 SW Clay Ave

35.90 51.0 Davis-Appanoose County line 70N 15W 18 NW --

39.23 34.9 313th Avenue 70N 16W 3 SE 313th Ave

41.66 26.5 Appanoose-Monroe County line 70N 16W 4 NW --

52.07 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Soap Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 103. Soap Creek, beginning at mouth in Wapello County.
SUPPLEMENTAL DATA 167

List of sites used to quantify main-channel slopes of the Soldier River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 445 Mouth of Soldier River 20N 12E 6 NE --

3.04 -- Interstate 29 80N 45W 11 SE --

3.77 440 County Road K45 (06608505, qw) 80N 45W 12 SW Austin Ave

8.72 -- Geneva Place 81N 44W 34 NE Geneva Pl

12.33 407 County Road F20, Pisgah (06608500, cont) 81N 44W 14 NE County Rd

13.97 -- State Highway 183 81N 44W 1 SW --

15.23 -- Harrison-Monona County line 81N 45W 1 NE --

20.71 -- County Roads E54 and L16, Moorhead 82N 43W 15 NE E54 Rd

26.29 281 Redwood Avenue 83N 42W 30 NW Redwood Ave

27.35 -- State Highway 37, Soldier 83N 42W 19 SE --

32.97 155 State Highway 183 (06608350, low) 84N 42W 34 SE --

37.48 135 State Highway 141 84N 42W 11 NW --

41.17 117 Monona-Crawford County line 85N 42W 25 SE --

44.68 105 C Avenue 85N 41W 16 NW C Ave

48.12 90.5 County Road L51 (06608300, low) 85N 41W 1 SW 150th St

49.14 59.1 Crawford-Ida County line 85N 41W 1 NE --

53.32 -- Harvest Avenue 86N 40W 21 SW Harvest Ave

57.99 -- U.S. Highway 59 86N 39W 19 SW --

67.22 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60

6

7

8

9

10

11

12

13

14

15

16

17

18

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Soldier River

[See section "Presentation of Curves" for explanation of list elements]

Figure 104. Soldier River, beginning at mouth in Harrison County.
168 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of South Beaver Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 116 Mouth of South Beaver Creek 90N 17W 25 NE --

0.22 -- U.S. Highway 20 90N 17W 25 E --

2.80 114 Butler-Grundy County line, Westbrook Street (05462800, 

low)

90N 17W 35 SE Westbrook St

7.33 -- County Road D17 89N 17W 22 NW 130th St

12.23 48.6 160th Street 88N 17W 6 NE 160th St

17.52 -- County Road T19 89N 18W 36 SW F Ave

23.29 19.6 C Avenue 88N 18W 5 SW C Ave

32.17 -- Des Moines Lobe landform region boundary 89N 19W 27 NE --

37.35 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of South Beaver Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 105. South Beaver Creek, beginning at mouth in Butler County.
SUPPLEMENTAL DATA 169

List of sites used to quantify main-channel slopes of the South English River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 128 Mouth of South English River 77N 9W 6 NE --

1.66 125 120th Street (05455450, low) 77N 9W 7 NW 120th St

2.17 -- Washington-Keokuk County line 77N 9W 7W --

5.68 111 318th Avenue 77N 10W 15 NE 318th Ave

11.91 101 280th Avenue (05455430, --) 77N 10W 18 NW 280th Ave

13.91 -- State Highway 149 77N 11W 14 SE --

18.17 88.5 240th Avenue (05455420, --) 77N 11W 21 NW 240th Ave

23.47 76.3 210th Avenue 77N 12W 24 NW 210th Ave

28.91 66.2 180th Avenue (05455400, low) 77N 12W 16 SW 180th Ave

32.29 49.5 150th Avenue 77N 13W 12 SW 150th Ave

34.36 -- State Highway 21 77N 13W 10 SW --

37.89 23.1 Keokuk-Mahaska County line 77N 13W 6 NW --

49.03 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

4

5

6

7

8

9

10

11

12

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the South English River

[See section "Presentation of Curves" for explanation of list elements]

Figure 106. South English River, beginning at mouth in Washington County.
170 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the South Fork Chariton River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 208 Appanoose-Wayne County line 70N 20W 36 SE --

3.60 -- County Road S56 69N 20W 10 SE S56 Rd

6.86 168 County Road S50 (06903700, cont) 69N 20W 5 SW 200th St

12.15 80.2 150th Street 69N 21W 5 SE 150th St

14.14 68.1 State Highway 14 (06903650, low) 69N 21W 6 NW --

17.56 58.0 County Road S23 (06903600, low) 70N 22W 34 SW 100th St

21.22 -- Ohio Street 69N 22W 9 SW Ohio St

24.31 -- State Highway 2 69N 22W 21 SW --

33.93 -- Drainage divide -- --

DISTANCE UPSTREAM FROM APPANOOSE-WAYNE COUNTY LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the South Fork Chariton River

[See section "Presentation of Curves" for explanation of list elements]

Figure 107. South Fork Chariton River, beginning at Appanoose-Wayne County line.
SUPPLEMENTAL DATA 171

List of sites used to quantify main-channel slopes of the South Fork Iowa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 309 Mouth of South Fork Iowa River 86N 19W 4 SW --

0.80 -- State Highway 215 86N 19W 5 NE --

3.08 306 T Avenue (05451270, qw) 87N 19W 30 SW T Ave

4.01 -- Des Moines Lobe landform region boundary 87N 20W 25 SE --

5.46 224 R Avenue (05451210, cont) 87N 20W 26 SW R Ave

6.76 223 State Highway 299 (05451200, low) 87N 20W 27 N --

11.16 130 State Highway 175 87N 20W 8 W --

12.82 -- N Avenue (05451130, qw) 87N 20W 7 NW N Ave

16.48 -- U.S. Highway 65 87N 21W 2 S --

21.35 117 KK Avenue 88N 21W 27 C KK Ave

26.18 109 I Avenue 88N 21W 20 SW I Ave

31.56 100 H Avenue 88N 21W 18 NW H Ave

33.73 -- U.S. Highway 20 88N 22W 12 W --

35.86 -- State Highway 359 88N 22W 11 NW --

41.18 79.5 C Avenue (05451100, low) 88N 22W 5 NW C Ave

41.59 -- Hydrologic Regions 1 and 2 boundary 88N 22W 6 NE --

64.53 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the South Fork Iowa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 108. South Fork Iowa River, beginning at mouth in Hardin County.
172 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the South Raccoon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,143 Mouth of South Raccoon River 78N 27W 21 NW --

1.48 -- Interstate 80 78N 27W 20 NW --

3.47 1,116 U.S. Highway 169 78N 27W 18 NW --

7.60 -- County Road P58 78N 28W 16 NE L Ave

14.30 994 H Avenue (05484000, cont) 78N 29W 2 NE H Ave

17.68 -- U.S. Highway 6 78N 29W 9 NE --

17.72 986 Downstream of mouth of Middle Raccoon River 78N 29W 9 NE --

17.72 377 Upstream of mouth of Middle Raccoon River 78N 29W 9 NE --

21.14 370 Dallas-Guthrie County line 78N 29W 7 SW --

25.31 -- County Road F61 78N 30W 10 SE 310th St

29.71 -- Walnut Trail 78N 30W 4 SE Walnut Trl

34.67 -- 285th Street 78N 30W 6 NE 285th St

37.46 -- Tank Avenue 79N 30W 29 SW Tank Ave

40.94 267 County Road F51 (05483340, low) 79N 31W 26 NE Montieth Rd

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

4

6

8

10

12

14

16

18

20

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the South Raccoon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 109. South Raccoon River, beginning at mouth in Dallas County.
SUPPLEMENTAL DATA 173

43.03 264 Downstream of mouth of Brushy Creek 79N 31W 22 NE --

43.03 122 Upstream of mouth of Brushy Creek 79N 31W 22 NE --

44.26 -- Pecan Avenue 79N 31W 22 NW Pecan Ave

48.59 84.0 State Highway 25, Guthrie Center (05483312, --) 79N 31W 7 NE 5th St

49.11 -- State Highway 44, Guthrie Center 79N 31W 6 SW State St

51.66 77.2 Locust Avenue (05483310, low) 80N 32W 36 SW Locust Ave

54.44 -- County Road N70 80N 32W 34 NW Justice Rd

57.66 -- County Road F32 80N 32W 20 NW 190th Rd

60.44 -- Fir Avenue 80N 33W 12 C Fir Ave

71.87 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the South Raccoon River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 109. South Raccoon River, beginning at mouth in Dallas County—Continued.
174 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the South River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 590 Mouth of South River 77N 22W 12 SW --

2.83 -- State Highway 5 77N 22W 26 NW --

2.90 -- Hydrologic Regions 2 and 3 boundary 77N 22W 26 SW --

6.27 -- 215th Place 76N 22W 9 NE 215th Pl

9.55 474 State Highway 92 76N 22W 19 NE --

13.68 460 168th Avenue (05487470, cont) 76N 23W 34 SE 168th Ave

17.64 -- U.S. Highway 65 75N 23W 6W --

18.78 278 118th Avenue (05487200, low) 75N 24W 2 NE 118th Ave

22.88 -- County Road R57 75N 24W 5 S 85th Ave

24.79 -- County Road G50 75N 25W 12 NE Monroe Pl

31.52 94.6 Quebec Street 74N 25W 1 NE Quebec St

35.72 65.4 County Road G64 (05486700, low) 74N 25W 16 NE Stone St

39.88 -- Interstate 35 74N 25W 19 NW --

40.04 54.5 Warren-Madison County line 74N 25W 19 W --

43.36 43.5 County Road R35 74N 26W 26 SW Wildrose Ave

46.89 36.6 Madison-Clarke County line 74N 26W 33 S --

52.54 23.6 County Road R21 73N 27W 12 SW 150th Ave

62.04 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the South River

[See section "Presentation of Curves" for explanation of list elements]

Figure 110. South River, beginning at mouth in Warren County.
SUPPLEMENTAL DATA 175

List of sites used to quantify main-channel slopes of Squaw Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 227 Mouth of Squaw Creek, Ames 83N 24W 12 SW --

0.82 225 U.S. Highway 69, Ames (05470800, --) 83N 24W 11 SE S Duff Ave

2.47 204 Lincoln Way, Ames (05470500, cont) 83N 24W 3 S Lincoln Way

7.65 170 County Road E26 84N 24W 20 W Cameron School 

Rd

10.52 150 Story-Boone County line, County Road R38 84N 24W 7 W 500th Ave

14.79 -- 150th Street 85N 25W 35 NW 150th St

18.39 -- County Road E18 85N 25W 22 NW 130th St

18.57 -- Hydrologic Regions 1 and 2 boundary 85N 25W 22 NW --

23.89 62.5 Boone-Hamilton County line, 100th Street 85N 25W 5 N 100th St

41.96 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

6.0

6.2

6.4

6.6

6.8

7.0

7.2

7.4

7.6

7.8

8.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Squaw Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 111. Squaw Creek, beginning at mouth in Story County.
176 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Squaw Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 136 Mouth of Squaw Creek 75N 24W 2 NW --

2.34 134 Nevada Street (05487100, low) 75N 24W 15 NE Nevada St

7.98 -- County Road G64 74N 24W 9 NE Roosevelt St

11.62 -- County Road G76 74N 24W 27 NE Hwy G76

17.62 79.6 Warren-Clarke County line 74N 25W 36 SW --

22.13 60.8 250th Avenue (05486900, low) 73N 25W 16 NE 250th Ave

25.91 -- Interstate 35 73N 25W 19 S --

29.35 21.0 195th Avenue 73N 26W 27 SE 195th Ave

41.75 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Squaw Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 112. Squaw Creek, beginning at mouth in Warren County.
SUPPLEMENTAL DATA 177

List of sites used to quantify main-channel slopes of Sugar Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 222 Mouth of Sugar Creek 78N 2W 17 SE --

4.17 218 U.S. Highway 6 (05464920, low) 78N 2W 15 N --

6.92 98.4 Muscatine-Cedar County line 78N 2W 3 NE --

11.88 -- Interstate 80 79N 2W 15 SE --

19.12 80.7 270th Street (05464850, low) 80N 2W 26 S 270th St

23.70 -- 250th Street 80N 2W 20 NE 250th St

28.48 -- State Highway 130 80N 2W 4 N --

31.13 19.3 200th Street 81N 2W 29 NE 200th St

38.01 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

4

5

6

7

8

9

10

11

12

13

14

15

16

17

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Sugar Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 113. Sugar Creek, beginning at mouth in Muscatine County.
178 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Sugar Creek tributary to the Des Moines River,—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 111 Mouth of Sugar Creek 65N 6W 25 N --

4.86 105 County Road W62 (05491000, cont) 65N 5W 7 NW Argyle Rd

9.06 92.5 White Plains Road 66N 5W 31 C White Plains Rd

14.22 76.5 County Road J72 66N 6W 14 NE 300th St

19.93 62.3 194th Avenue (05490700, low) 67N 6W 33 NW 194th Ave

24.33 51.3 245th Street 67N 6W 18 E 245th St

28.38 40.8 State Highway 2 67N 6W 6 NE --

33.00 25.5 County Road J56 68N 7W 24 SE Primrose Rd

45.24 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

4.0

4.5

5.0

5.5

6.0

6.5

7.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Sugar Creek, tributary to the Des Moines River

[See section "Presentation of Curves" for explanation of list elements]

Figure 114. Sugar Creek, tributary to the Des Moines River, beginning at mouth in Lee County.
SUPPLEMENTAL DATA 179

List of sites used to quantify main-channel slopes of Sugar Creek tributary to the Mississippi River,—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 152 Mouth of Sugar Creek 67N 5W 26 NE --

1.96 -- U.S. Highway 61 67N 5W 15 SW --

3.40 109 235th Street (05474300, low) 67N 5W 9 SE 235th Street

5.89 105 State Highway 2 67N 5W 5 C --

10.08 75.6 225th Avenue (05474200, low) 68N 5W 30 NE 225th Ave

13.06 -- Franklin Road 68N 6W 13 SW Franklin Rd

17.07 -- State Highway 103 68N 6W 2 E --

19.34 24.0 205th Avenue 69N 6W 26 S 205th Ave

29.66 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Sugar Creek, tributary to the Mississippi River

[See section "Presentation of Curves" for explanation of list elements]

Figure 115. Sugar Creek, tributary to the Mississippi River, beginning at mouth in Lee County.
180 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Tarkio River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 206 Iowa-Missouri State line, Blanchard 67N 38W 32 NW --

1.25 200 County Road J64 (06812000, cont) 67N 38W 29 NE 310th St

5.42 175 County Road J52, Coin 67N 38W 5 NE 270th St

9.74 155 County Road J40 (06811900, low) 68N 38W 16 N 230th St

11.90 -- State Highway 2 69N 38W 34 N --

17.06 80.3 160th Street 69N 38W 2 NE 160th St

20.20 74.7 130th Street 70N 38W 24 N 130th St

23.36 66.6 M Avenue (06811860, low) 70N 37W 5 NW M Ave

23.70 66.6 Page-Montgomery County line 70N 37W 5 NW --

26.85 53.5 County Road H46 71N 37W 21 NW 250th St

29.43 49.3 County Road H42, Stanton (06811840, cont) 71N 37W 4 W 225th St

30.44 -- U.S. Highway 34 72N 37W 33 NW --

35.46 -- 170th Street 72N 37W 9 NW 170th St

47.50 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Tarkio River

[See section "Presentation of Curves" for explanation of list elements]

Figure 116. Tarkio River, beginning at Iowa-Missouri State line in Page County.
SUPPLEMENTAL DATA 181

List of sites used to quantify main-channel slopes of the Thompson River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 729 Iowa-Missouri State line 67N 26W 25 W --

5.76 701 U.S. Highway 69, Davis City (06898000, cont) 68N 26W 35 SE Bridge St

10.43 -- Interstate 35 68N 26W 28 SW --

13.40 -- County Road R30 68N 26W 17 SE --

20.76 -- County road 68N 26W 5 NW --

23.62 -- State Highway 2 69N 26W 31 NW --

26.28 -- County Road J34 69N 26W 20 SW --

32.58 -- County road 69N 27W 1 NE --

37.32 -- County Road J20, Grand River 70N 27W 34 SE --

44.37 401 County Road R15 (06897900, low) 70N 27W 16 NW --

48.74 393 Decatur-Ringgold County line 70N 27W 6 NW --

49.33 -- Ringgold-Union County line 71N 28W 36 SE --

55.43 -- County Road H45 71N 28W 11 S Willow Ave

58.59 -- County Road P64 71N 28W 2 SW Willow Ave

64.24 -- County Road H37 72N 28W 33 NE 210th St

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Thompson River

[See section "Presentation of Curves" for explanation of list elements]

Figure 117. Thompson River, beginning at Iowa-Missouri State line in Decatur County.
182 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

69.82 231 U.S. Highway 34 (06897820, low) 72N 28W 17 SW --

76.22 -- Wolf Creek Drive 73N 28W 31 SE Wolf Creek Dr

79.97 -- Hydrologic Regions 2 and 3 boundary 73N 29W 24 SE --

83.28 -- County Road H17 73N 29W 11 NE Rea Rd

85.86 129 Union-Madison County line 74N 29W 34 SE --

92.83 91.0 County Road G61 74N 29W 17 SE Macksburg Rd

96.83 81.7 Madison-Adair County line 74N 29W 7 NW --

98.21 80.0 York Avenue (06897770, low) 74N 30W 1 SW York Ave

102.69 -- 260th Street 75N 30W 27 NW 260th St

105.94 33.4 State Highway 92 75N 30W 17 NE --

115.72 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Thompson River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 117. Thompson River, beginning at Iowa-Missouri State line in Decatur County--Continued.
SUPPLEMENTAL DATA 183

List of sites used to quantify main-channel slopes of Timber and South Timber Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 124 Mouth of Timber Creek 83N 17W 3 NW --

3.59 118 Shady Oaks Road (05451700, cont) 83N 17W 8 SW Shady Oaks Rd

3.77 118 U.S. Highway 30 83N 17W 8 SW --

7.36 62.0 County Road E49 (05451650, low) 83N 17W 21 SW 260th St

12.32 35.7 Smith Avenue, Ferguson 82N 17W 6 SW Smith Ave

15.97 -- State Highway 14 82N 18W 2 SW --

24.01 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

6

7

8

9

10

11

12

13

14

15

16

Timber Creek South Timber Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Timber and South Timber Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 118. Timber and South Timber Creeks, beginning at mouth of Timber Creek in Marshall County.
184 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Troublesome Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 131 Mouth of Troublesome Creek 77N 36W 32 SW --

2.77 128 635th Street (06809150, low) 76N 36W 3 NE 635th St

4.34 124 U.S. Highways 6 and 71 (06809140, --) 77N 36W 36 SW --

7.68 118 Edgewood Road 77N 35W 29 NW Edgewood Rd

10.77 -- County Road N28 77N 35W 16 NE 690th St

13.06 -- Interstate 80 77N 35W 3 NE --

13.77 68.4 Cass-Audubon County line, Akron Road (06809100, low) 77N 35W 2 NW Akron Rd

18.24 52.4 310th Street 78N 35W 13 NE 310th St

21.41 -- Quail Avenue 78N 34W 4 SW Quail Ave

24.69 23.9 Audubon-Guthrie County line 79N 34W 36 NE --

35.22 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

6

7

8

9

10

11

12

13

14

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Troublesome Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 119. Troublesome Creek, beginning at mouth in Cass County.
SUPPLEMENTAL DATA 185

List of sites used to quantify main-channel slopes of Turkey Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 134 Mouth of Turkey Creek 75N 37W 2 C --

0.19 133 U.S. Highway 6 (06809300, low) 75N 37W 2 C --

4.22 -- County Road N16 76N 36W 32 W 610th St

6.15 -- U.S. Highway 71 76N 36W 28 SE --

10.83 -- Jackson Road 76N 36W 14 E Jackson Rd

12.72 69.5 665th Street (06809250, low) 76N 35W 7 SE 665th St

15.46 52.8 County Road N28 76N 35W 3 SW 690th St

19.32 39.4 725th Street 77N 34W 31 C 725th St

21.93 27.3 State Highway 148, Anita 77N 34W 28 NE Michigan St

32.93 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Turkey Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 120. Turkey Creek, beginning at mouth in Cass County.
186 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Turkey River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 1,684 Mouth of Turkey River 91N 2W 12 NE --

5.24 -- U.S. Highway 52 91N 2W 9 SE --

12.96 1,606 County Roads C43 and X47, Osterdock 91N 3W 2 NE Osterdock Rd

21.16 1,545 County Road C43, Garber (05412500, cont) 92N 4W 36 NW Jupiter Rd

21.84 -- County Road C7X, Elkport 92N 4W 35 NE Co Rd C7X

29.16 1,047 Mouth of Panther Creek 92N 4W 9 SW --

33.79 -- Galaxy Road 92N 4W 6 SE Galaxy Rd

39.09 903 State Highway 13 (05412020, cont) 93N 5W 26 NW --

40.36 891 Bridge Street, Elkader (05412000, cont) 93N 5W 23 SW Bridge St

47.10 875 North line of section 5 93N 5W 5 NW --

52.36 852 County Road W70 94N 6W 26 SW Cable Ave

58.47 814 Clayton-Fayette County line 94N 6W 18 SW --

59.65 -- County Road B64, Elgin 94N 7W 13 NW Agate Rd

64.38 -- U.S. Highway 18, Clermont 95N 7W 34 SW Mill St

68.86 -- County Road B40 95N 7W 30 SE Great River Rd

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Turkey River

[See section "Presentation of Curves" for explanation of list elements]

Figure 121. Turkey River, beginning at mouth in Clayton County.
SUPPLEMENTAL DATA 187

74.23 -- Ironwood Road 95N 8W 22 SE Ironwood Rd

78.22 -- County Road B40 95N 8W 15 SE Great River Rd

83.59 641 County Road B40 (05411850, cont) 95N 8W 8 SE Great River Rd

87.06 -- State Highway 150 95N 8W 18 NW --

90.07 -- Orange Road 95N 9W 2 SE Orange Rd

92.04 264 Fayette-Winneshiek County line 95N 9W 3 NW --

95.19 250 123rd Street 96N 9W 21 SE 123rd St

99.25 -- County Road B32 96N 9W 16 NW Co Rd B32

101.14 -- State Highway 24, Fort Atkinson 96N 9W 8 SE 1st St

105.18 -- 160th Street 96N 9W 6 NW 160th St

110.30 -- State Highway 325, Spillville 97N 9W 19 SE --

110.82 177 County Road W14, Spillville (05411600, cont) 97N 9W 19 NE Main St

115.89 134 210th Street 97N 10W 11 NE 210th St

119.69 -- 230th Street 98N 10W 34 NW 230th St

124.08 -- Madison Road 98N 10W 17 NE Madison Rd

127.62 95.9 Winneshiek-Howard County line, 345th Avenue 98N 10W 7 NW 345th Ave

132.10 87.0 County Road V58 (05411560, low) 98N 11W 2 NW Willow Ave

133.71 -- Valley Avenue, Vernon Springs 99N 11W 34 SW Valley Ave

137.55 72.9 Mouth of North Branch Turkey River 99N 11W 31 SW --

141.19 -- County Road V46 98N 12W 1 SW Robin Ave

148.42 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Turkey River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 121. Turkey River, beginning at mouth in Clayton County—Continued.
188 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Upper Iowa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Mouth of Upper Iowa River 100N 4W 19 NE --

3.25 1,005 State Highway 26 (05388340, low) 100N 4W 15 SE --

5.44 987 Morgan Bridge Road 100N 4W 28 NW Morgan Bridge Rd

8.61 -- Hartley Drive 100N 4W 31 NW Hartley Dr

12.01 -- County Road X6A 100N 5W 34 SE Hartley Dr

14.98 -- Green Leaf Road 99N 5W 5 NW Green Leaf Rd

18.28 770 State Highway 76 (05388250, cont) 99N 6W 1 NW --

24.37 -- Iverson Bridge Road 99N 6W 8 NE Iverson Bridge Rd

31.27 731 County Road W60 99N 6W 29 NE Ellingson Bridge 

Rd

36.58 -- Ferris Mill Road 99N 6W 30 S Ferris Mill Rd

37.68 651 Allamakee-Winneshiek County line 99N 6W 31 NW --

38.57 -- Lundy Bridge Road 99N 7W 36 SE Lundy Bridge Rd

44.02 -- 143rd Avenue 98N 7W 9 SE 143rd Ave

48.53 -- River Road 98N 7W 7 NE River Rd

52.49 568 Clay Hill Road, Freeport (05388000, cont) 98N 8W 13 NE Clay Hill Rd

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Upper Iowa River

[See section "Presentation of Curves" for explanation of list elements]

Figure 122. Upper Iowa River, beginning at mouth in Allamakee County.
SUPPLEMENTAL DATA 189

56.98 511 College Drive, Decorah (05387500, cont) 98N 8W 16 SW College Dr

59.11 -- U.S. Highway 52 98N 8W 8 SW --

63.16 -- County Road W20 98N 8W 6 NW Bluffton Rd

67.68 420 Scenic River Road 99N 9W 25 E Scenic River Rd

73.88 367 County Road W20, Bluffton (05387440, cont) 99N 9W 10 NE Bluffton Rd

78.99 361 Chimney Rock Road 99N 9W 5 NE Chimney Rock Rd

83.40 333 Cattle Creek Road 99N 9W 6 S Cattle Creek Rd

87.32 287 Coldwater Creek Road 100N 10W 35 SE Coldwater Creek 

Rd

91.52 -- State Highway 139, Kendallville 100N 10W 33 NE --

94.10 273 360th Street (05387400, low) 100N 10W 21 C 360th St

98.61 248 Winneshiek-Howard County line, 345th Avenue 100N 10W 7 SW 345th Ave

104.55 224 Minnesota-Iowa State line 100N 11W 11 NW --

109.18 -- Iowa-Minnesota State line 100N 11W 8 NW --

115.20 203 Quail Avenue 100N 12W 14 NW Quail Ave

119.42 -- County Road V36 100N 12W 21 SW Oak Ave

122.54 -- Mill Road 100N 12W 19 C Mill Rd

127.42 141 U.S. Highway 63, Chester (05387300, low) 100N 13W 10 SE Main St

130.89 110 Howard Avenue 100N 13W 8 C Howard Ave

134.57 84.2 Iowa-Minnesota State line 100N 14W 12 NW --

154.73 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Upper Iowa River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 122. Upper Iowa River, beginning at mouth in Allamakee County—Continued.
190 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Volga River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 403 Mouth of Volga River 92N 4W 26 SE --

0.52 -- County Road X3C 92N 4W 26 SE Grandview Rd

9.33 348 County Road X21, Littleport (05412400, cont) 92N 5W 25 SE Littleport Rd

14.67 -- Evergreen Road, Mederville 92N 5W 22 SW Evergreen Rd

19.18 -- State Highway 13, Osborne 92N 5W 9 SW --

27.52 -- County Road C2W, Volga City 92N 6W 10 NE Co Rd C2W

27.78 261 Cass Street, Volga City 92N 6W 10 NW Cass St

34.93 -- Clayton-Fayette County line 93N 6W 30 SW --

35.85 -- Acorn Road 93N 7W 25 C Acorn Rd

38.42 -- County Road W51, Wadena 93N 7W 27 S Mill St

42.04 167 Fox Road 93N 7W 30 SE Fox Rd

45.92 -- Heron Road 93N 8W 13 SW Heron Rd

55.87 -- Main Street, Fayette 93N 8W 28 NW Main St

56.33 130 State Highway 150, Fayette (05412340, --) 93N 8W 29 NE --

56.77 -- State Highway 93, Fayette 93N 8W 29 NW --

61.11 -- M Avenue 93N 8W 30 SW M Ave

64.76 53.0 County Road W25 (05412200, low) 93N 9W 35 SW O Ave

69.98 -- State Highway 93 93N 9W 30 NE --

81.12 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Volga River

[See section "Presentation of Curves" for explanation of list elements]

Figure 123. Volga River, beginning at mouth in Clayton County.
SUPPLEMENTAL DATA 191

List of sites used to quantify main-channel slopes of Walnut Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 223 Mouth of Walnut Creek 69N 41W 8 SW --

1.90 222 County Road L68 (06808800, low) 69N 41W 9 E 330th Ave

7.95 -- 160th Street 69N 40W 4 N 160th St

13.49 -- State Highway 184 70N 40W 12 S --

14.77 -- U.S. Highway 59 70N 40W 1 SE --

15.29 161 Fremont-Page County line 70N 40W 1 NE --

16.15 159 Page-Montgomery County line 70N 39W 6 NW --

20.44 140 240th Street (06808700, low) 71N 39W 17 NW 240th St

23.38 -- County Road M37 72N 39W 33 C Boxelder Ave

26.96 108 U.S. Highway 34 72N 39W 23 NE --

31.48 -- County Road H20 73N 38W 30 SW 150th St

37.06 82.4 Montgomery-Pottawattamie County line 73N 38W 4 NW 100th St

42.25 70.4 State Highway 92 74N 38W 9 NE --

46.51 61.2 Hackberry Road (06808600, low) 75N 38W 22 NW Hackberry Rd

48.71 -- U.S. Highway 6 75N 38W 9 NE --

53.44 37.4 Magnolia Road 76N 38W 22 NE Magnolia Rd

58.52 -- State Highway 83 77N 38W 26 NW --

66.63 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Walnut Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 124. Walnut Creek, beginning at mouth in Fremont County.
192 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Walnut and Middle Walnut Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 102 Mouth of Walnut Creek 72N 8W 2 NE --

5.85 66.3 County Road W40 (05473100, low) 73N 8W 27 SW Germanville Rd

11.23 53.8 Spruce Avenue 73N 8W 19 SW Spruce Ave

15.84 -- Orange Boulevard 73N 9W 21 SE Orange Blvd

27.26 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

6

7

8

9

10

11

12

13

14

15

Walnut Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

Middle Walnut Creek

List of sites used to quantify main-channel slopes of Walnut and Middle Walnut Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 125. Walnut and Middle Walnut Creeks, beginning at mouth of Walnut Creek in Jefferson County.
SUPPLEMENTAL DATA 193

List of sites used to quantify main-channel slopes of Wapsinonoc and West Branch Wapsinonoc Creeks—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 189 Mouth of Wapsinonoc Creek 77N 3W 19 SW --

3.98 161 State Highway 22 (05464980, qw) 77N 4W 11 SE --

7.84 111 County Road F70 78N 4W 36 NW 155th St

13.66 54.1 County Road F62, West Liberty (05464950, low) 78N 4W 14 NE 121st St

15.99 46.6 U.S. Highway 6, West Liberty (05464948, --) 78N 4W 10 NE --

19.75 -- Muscatine-Cedar County line 78N 4W 4 NW --

23.00 17.7 County Road X30, Downey 79N 4W 29 SW Baker Ave

31.72 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

4

5

6

7

8

9

10

11

12

13

Wapsinonoc Creek West Branch Wapsinonoc Creek

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

Unnamed Tributary

List of sites used to quantify main-channel slopes of Wapsinonoc and West Branch Wapsinonoc Creeks

[See section "Presentation of Curves" for explanation of list elements]

Figure 126. Wapsinonoc and West Branch Wapsinonoc Creeks, beginning at mouth of Wapsinonoc Creek 

in Muscatine County.
194 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 2,540 Mouth of Wapsipinicon River 80N 5E 13 SE --

3.59 2,536 U.S. Highway 67 80N 5E 22 NE --

10.34 2,484 County Road Z30 (05422110, --) 80N 4E 12 NE 240th Ave

18.19 2,330 State Highway 956 (05422000, cont) 80N 4E 6 NE --

20.57 -- U.S. Highway 61 80N 3E 1 SW --

29.17 2,207 County Road Y52 (05421880, --) 80N 2E 12 NW 115th Ave

34.60 2,082 End of Buena Vista Road (05421840, --) 80N 2E 16 NW --

38.41 2,053 60th Avenue 80N 2E 6 NW 60th Ave

45.01 1,928 U.S. Highway 30 81N 1E 14 N --

54.28 1,834 County Road E63, Toronto (05421780, --) 82N 1E 17 NE 118th Ave

56.79 1,821 Clinton-Cedar County line 82N 1E 7 SW --

58.14 1,820 County Road Y24, Massillon (05421770, --) 82N 1E 11 SE Hoover Hwy

60.76 1,809 Cedar-Jones County line 83N 1W 36 SW --

65.19 1,792 County Road X64, Oxford Mills (05421760, low) 83N 1W 28 NE Co Rd X-64

69.12 -- County Road X75 83N 1W 18 SW 65th Ave

73.30 1,732 100th Avenue 83N 2W 15 NW 100th Ave

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

2

3

4

5

6

7

8

9

10

11

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Wapsipinicon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 127. Wapsipinicon River, beginning at mouth at Scott-Clinton County line.
SUPPLEMENTAL DATA 195

79.34 -- State Highway 38, Olin 83N 3W 12 S --

89.95 1,585 Lands Road 84N 3W 19 NE Lands Rd

92.68 1,575 Shoe Road (05421740, --) 84N 4W 13 SW Shoe Rd

92.88 -- U.S. Highway 151 84N 4W 14 SE --

94.95 1,562 County Road E34, Anamosa 84N 4W 10 NE Co Rd E-34

98.88 1,324 County Road X28, Stone City (05421500, cont) 84N 4W 6 NE Co Rd X-28

100.02 -- Jones-Linn County line 84N 4W 6 NW --

101.61 -- Matsell Park Road 85N 5W 36 SW Matsell Park Rd

110.83 1,294 County Road E28 85N 5W 20 NW Boy Scouts Rd

115.10 1,274 Jordans Grove Road 85N 6W 14 NE Jordans Grove Rd

118.68 1,263 State Highway 13, Central City (05421400, csg) 85N 6W 3 NE --

123.58 -- Sutton Road, Paris 86N 6W 19 SE Sutton Rd

132.32 1,215 County Road W45, Troy Mills 86N 7W 5 SE Troy Mills Rd

134.64 1,210 Linn-Buchanan County line 86N 7W 6 NW --

144.48 1,141 County Road W35, Quasequeton (05421330, --) 88N 7W 34 SE Water St

149.46 -- Nolan Avenue 88N 8W 32 NW Nolan Ave

155.19 -- U.S. Highway 20 88N 9W 11 SW --

157.30 -- State Highway 150, Independence 88N 9W 4 SE 3rd Ave SE

157.99 1,048 USGS gage at end of 6th Street, Independence (05421000, 

cont)

88N 9W 4 NE --

158.30 -- State Highway 939, Independence 89N 9W 34 SW 1st St W

164.79 -- Otterville Boulevard, Otterville 89N 10W 13 S Otterville Blvd

169.57 899 County Road D16, Littleton (05420910, --) 89N 10W 9 SE 175th St

173.90 676 Buchanan-Black Hawk County line 89N 10W 6 NW --

179.58 553 Bennington Road East 90N 11W 23 NW Bennington Rd E

183.76 545 State Highway 281 (05420770, --) 90N 11W 4 SE --

184.50 544 Black Hawk-Bremer County line 90N 11W 4 NE --

189.44 535 County Road C50 (05420760, --) 91N 11W 20 NE 252nd St

193.57 -- State Highway 3 91N 11W 8 NW --

199.66 511 County Road C33 92N 11W 19 NW 190th St

204.59 498 County Road C28, Tripoli (05420740, low) 92N 12W 2 SE 165th St

207.95 343 State Highway 93 (05420680, cont) 93N 12W 27 SW --

213.80 -- County Road C16, Frederika 93N 12W 18 NW 120th St

216.92 325 Bremer-Chickasaw County line, U.S. Highway 63 94N 13W 36 SW --

223.77 296 State Highway 346 (05420665, --) 94N 13W 15 NE --

225.13 291 260th Street (05420660, low) 94N 13W 10 NW 260th St

228.24 161 County Road B54 (05420580, low) 95N 13W 33 NW 240th St

232.60 -- County Road B57 95N 13W 19 NE 220th St

236.95 145 U.S. Highway 18 (05420570, --) 95N 14W 1 SW --

242.19 -- County Road B33 96N 14W 27 NE 170th St

247.90 120 County Road B28 96N 14W 9 NW 140th St

List of sites used to quantify main-channel slopes of the Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 127. Wapsipinicon River, beginning at mouth at Scott-Clinton County line—Continued.
196 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

254.11 102 Chickasaw-Howard County line, 100th Street 97N 14W 20 NW 100th St

257.23 95.2 County Road B17 (05420560, cont) 97N 14W 8 NW 190th St

260.74 -- 170th Street 98N 14W 31 NE 170th St

264.22 77.6 Howard-Mitchell County line, County Road T68 98N 14W 18 SW Addison Ave

267.79 72.3 390th Street (05420540, low) 98N 15W 12 NE 390th St

273.51 62.4 State Highway 9, Riceville 99N 15W 25 E --

278.98 44.6 440th Street 99N 15W 15 NE 440th St

284.30 -- County Road A23 100N 15W 34 NW 470th St

288.03 -- 490th Street 100N 15W 20 NE 490th St

297.48 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of the Wapsipinicon River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 127. Wapsipinicon River, beginning at mouth at Scott-Clinton County line—Continued.
SUPPLEMENTAL DATA 197

List of sites used to quantify main-channel slopes of Waterman Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 140 Mouth of Waterman Creek 94N 39W 26 N --

0.75 139 Waterman Boulevard (06606000, low) 94N 39W 23C Waterman Blvd

5.51 -- County Road B53 94N 39W 3 SE Wilson Ave

11.77 82.7 County Road B46 95N 39W 23 NW 420th St

18.27 58.4 Abandoned bridge, 390th Street (06605900, low) 95N 39W 4 NE --

22.03 -- 370th Street 96N 39W 29 NE 370th St

25.90 50.1 350th Street 96N 39W 18 NE 350th St

30.49 28.7 U.S. Highway 18 (06605890, csg) 97N 40W 36 NE --

33.52 18.8 300th Street 97N 39W 19 NW 300th St

43.98 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Waterman Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 128. Waterman Creek, beginning at mouth in O’Brien County.
198 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the Weldon River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 240 Iowa-Missouri State line 67N 24W 28 W --

1.16 228 County Road J66 (06898450, low) 67N 24W 22 NW --

3.22 -- County Road R52 67N 24W 10 NE --

10.00 104 County Road J46 (06898400, cont) 68N 24W 17 NE --

14.56 72.4 State Highway 2 (06898300, low) 69N 24W 20 SE --

19.30 36.5 County Road J20 70N 24W 33 SW --

24.73 -- County Road J22 70N 24W 16 SW --

37.44 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

6.0

6.2

6.4

6.6

6.8

7.0

7.2

7.4

7.6

7.8

8.0

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Weldon River

[See section "Presentation of Curves" for explanation of list elements]

Figure 129. Weldon River, beginning at Iowa-Missouri State line in Decatur County.
SUPPLEMENTAL DATA 199

List of sites used to quantify main-channel slopes of the West Branch Floyd River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 281 Mouth of West Branch Floyd River 91N 46W 2 SE --

0.06 -- U.S. Highway 75, Merrill 91N 46W 2 SE --

2.17 232 County Road C38 (06600400, low) 92N 46W 35 NE Co Rd C38

6.00 225 State Highway 3 92N 46W 13 NE --

9.95 -- 150th Street 93N 45W 31 NE 150th St

12.35 209 130th Street 93N 45W 19 NE 130th St

16.76 194 Plymouth-Sioux County line, 100th Street 93N 45W 5 NE 100th St

18.27 180 County Road B62 (06600300, cont) 94N 45W 32 NE 500th St

18.50 -- U.S. Highway 75 94N 45W 29 SE --

19.33 -- U.S. Highway 75 94N 45W 28 NW --

23.44 140 County Road B58, Maurice 94N 45W 17 NW 470th St

26.82 125 State Highway 10 94N 45W 5 NE --

26.99 -- U.S. Highway 75 95N 45W 32 SE --

32.98 91.2 County Road B46 95N 45W 23 NW 420th St

36.22 69.3 County Road B40 95N 45W 12 NW 400th St

41.95 59.7 County Road B30 (06600250, low) 96N 44W 30 NE 370th St

45.63 34.8 350th Street 96N 44W 17 NW 350th St

55.65 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Branch Floyd River

[See section "Presentation of Curves" for explanation of list elements]

Figure 130. West Branch Floyd River, beginning at mouth in Plymouth County.
200 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the West Branch One Hundred and Two River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 125 Mouth of West Branch 102 River 68N 35W 10 NW --

0.94 123 220th Street (06819140, low) 69N 35W 35 SW 220th St

7.55 106 Abandoned Bridge, 170th Street (06819120, low) 69N 34W 7 NW 170th St

10.17 52.2 Granite Avenue (06819100, low) 70N 34W 31 SE Granite Ave

15.53 41.0 State Highway 148 70N 34W 14 SW --

19.86 24.5 Taylor-Adams County line 70N 33W 6 NW Adams-Taylor St

30.01 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Branch One Hundred and Two River

[See section "Presentation of Curves" for explanation of list elements]

Figure 131. West Branch One Hundred and Two River, beginning at mouth in Taylor County.
SUPPLEMENTAL DATA 201

List of sites used to quantify main-channel slopes of the West Fork Cedar River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 2,639 Mouth of West Fork Cedar River 90N 14W 16 NE --

1.77 -- Downstream of mouth of Shell Rock River 90N 14W 4 SE --

1.77 -- Upstream of mouth of Shell Rock River 90N 14W 4 SE --

5.36 846 County Road C55, Finchford (05458900, cont) 90N 14W 6 SE Finchford Rd

6.33 -- Black Hawk-Butler County line 90N 14W 7 NW --

12.91 -- County Road T55 90N 15W 5 C Temple Ave

19.59 770 County Road T47 (05458890, --) 91N 16W 33 NE Sinclair Ave

25.20 736 State Highway 14 (05458884, --) 91N 16W 19 SW --

29.51 705 Jackson Avenue (05458878, --) 91N 17W 15 NE Jackson Ave

33.72 691 County Road T25 (05458875, --) 91N 17W 7 SE Hickory Ave

39.72 298 State Highway 3, Dumont 92N 18W 34 NE --

46.69 285 Butler-Franklin County line, Franklin Avenue 92N 18W 7 SW Franklin Ave

50.65 -- 200th Street 92N 19W 2 NW 200th St

54.27 -- Hydrologic Regions 1 and 2 boundary 93N 19W 28 SW --

95.81 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Fork Cedar River

[See section "Presentation of Curves" for explanation of list elements]

Figure 132. West Fork Cedar River, beginning at mouth in Black Hawk County.
202 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of West Fork Ditch and West Fork Little Sioux River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 -- Monona-Woodbury County line, 100th Street 86N 45W 33 SE 100th St

0.99 403 State Highway 141 (06602020, cont) 86N 45W 27 SW --

3.24 399 Humbolt Street (06602000, cont) 86N 45W 16 SE Humbolt St

4.02 395 State Highway 982 86N 45W 9 SE --

8.64 383 County Road 87N 45W 21 S --

12.40 372 230th Street 87N 45W 10 NW 230th St

17.61 359 Abandoned bridge, 190th Street 88N 45W 21 NE --

21.83 344 Abandoned bridge, 160th Street (06601900, low) 89N 44W 31 SE --

22.33 -- U.S. Highway 20, Moville 89N 44W 31 E --

26.72 -- Humbolt Street 89N 44W 17 SE Humbolt St

32.49 241 Woodbury-Plymouth County line 89N 44W 3 NE --

36.38 219 Quorn Road, Kingsley (06601700, low) 90N 44W 25 NW Quorn Rd

39.39 -- State Highway 140 90N 43W 17 NW --

43.02 147 County Road C60 90N 43W 10 NE Co Rd C60

44.71 135 Tamarack Avenue (06601600, low) 90N 43W 1 NW Tamarack Ave

46.40 -- Plymouth-Cherokee County line, A Avenue 91N 43W 36 NE A Ave

DISTANCE UPSTREAM FROM MONONA-WOODBURY COUNTY LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

West Fork Little Sioux River

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

West Fork Ditch

List of sites used to quantify main-channel slopes of West Fork Ditch and West Fork Little Sioux River

[See section "Presentation of Curves" for explanation of list elements]

Figure 133. West Fork Ditch and West Fork Little Sioux River, beginning at Monona-Woodbury

 County line.
SUPPLEMENTAL DATA 203

50.14 45.8 580th Street 91N 42W 29 NE 580th St

53.95 -- 560th Street 91N 42W 10 SW 560th St

57.05 -- 540th Street 91N 42W 3 NE 540th St

60.63 27.4 520th Street 92N 42W 26 NE 520th St

64.95 -- State Highway 3 92N 42W 1 SW --

72.77 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of West Fork Ditch and West Fork Little Sioux River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 133. West Fork Ditch and West Fork Little Sioux River, beginning at Monona-Woodbury County 

line—Continued.
204 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the West Fork Middle Nodaway River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 129 Mouth of West Fork Middle Nodaway River 74N 33W 33 N --

0.67 128 330th Street (06816800, low) 74N 33W 28 C 330th St

4.31 -- County Road G63 74N 33W 9 NW 290th St

7.31 -- State Highway 92 75N 33W 34 NW --

9.54 -- 250th Street 75N 33W 22 NE 250th St

14.48 67.9 225th Street (06816700, low) 75N 33W 4 C 225th St

18.96 -- County Road G35 76N 33W 19 NE 190th St

22.14 14.4 County Road G27 76N 33W 6 N 160th St

29.98 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24

7

8

9

10

11

12

13

14

15

16

17

18

19

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Fork Middle Nodaway River

[See section "Presentation of Curves" for explanation of list elements]

Figure 134. West Fork Middle Nodaway River, beginning at mouth in Adair County.
SUPPLEMENTAL DATA 205

List of sites used to quantify main-channel slopes of the West Fork One Hundred and Two River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 212 Iowa-Missouri State line 67N 35W 27 S --

3.22 -- County Road J55 67N 35W 10 S 300th St

6.76 -- 265th Street 68N 35W 27 W 265th St

9.83 183 State Highway 2 (06819150, low) 68N 35W 10 NW --

15.04 -- 185th Street 69N 35W 15 C 185th St

20.61 -- 140th Street 70N 35W 25 NW 140th St

26.10 17.9 Taylor-Adams County line 70N 35W 1 NE Adams-Taylor St

39.06 -- Drainage divide -- --

DISTANCE UPSTREAM FROM IOWA-MISSOURI STATE LINE, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Fork One Hundred and Two River

[See section "Presentation of Curves" for explanation of list elements]

Figure 135. West Fork One Hundred and Two River, beginning at Iowa-Missouri State line in Taylor 

County.
206 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of the West Fork West Nishnabotna River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 151 Mouth of West Fork West Nishnabotna River 79N 38W 17 NW --

0.84 146 County Road M36, Harlan (06807300, low) 79N 38W 7 NE Mulberry Rd

5.91 -- County Road F32 80N 38W 18 SE F32 Rd

11.38 -- Linden Road 81N 39W 36 NE Linden Rd

13.81 -- Linden Road, Defiance 81N 39W 24 NW Linden Rd

18.22 71.5 Shelby-Crawford County line, County Road F16 81N 38W 5 NE F16 Rd

20.67 64.2 320th Street (06807280, low) 82N 38W 35 W 320th St

23.43 -- State Highway 141 82N 38W 14 SE --

27.79 -- County Road E53 82N 37W 6 NE S Ave

37.31 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

6

7

8

9

10

11

12

13

14

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the West Fork West Nishnabotna River

[See section "Presentation of Curves" for explanation of list elements]

Figure 136. West Fork West Nishnabotna River, beginning at mouth in Shelby County.
SUPPLEMENTAL DATA 207

List of sites used to quantify main-channel slopes of White Breast Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 430 Mouth of White Breast Creek 76N 19W 10 SW --

5.67 403 State Highway 14 76N 20W 24 C --

11.33 380 State Highways 5 and 92 (05488000, cont) 75N 20W 3 SW --

12.46 -- Hydrologic Regions 1 and 2 boundary 75N 20W 9 SE --

16.08 357 70th Avenue 75N 20W 19 SW 70th Ave

18.55 -- State Highway 181 75N 21W 26 SE --

20.72 342 Quebec Drive (05487980, cont) 74N 21W 3 NW Quebec Dr

26.43 -- Marion-Warren County line, 10th Avenue 74N 21W 18 SW 10th Ave

31.72 243 Warren-Lucas County line, County road (05487900, low) 74N 22W 35 SE --

36.60 -- County Road S23 73N 22W 14 SW --

41.01 -- County road 73N 22W 33 NE --

43.96 -- County road (05487810, qw) 73N 22W 5 SW --

47.30 133 U.S. Highway 34 72N 22W 18 SW --

49.68 128 U.S. Highway 65, Lucas (05487800, csg) 72N 23W 23 NE --

56.49 -- County road 72N 23W 32 NE --

60.61 88.9 Lucas-Clarke County line 71N 23W 6 NE --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

4

5

6

7

8

9

10

11

12

13

Curve adjusted 17.7 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of White Breast Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 137. White Breast Creek, beginning at mouth in Marion County.
208 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

62.60 82.9 330th Avenue (05487700, qw) 71N 24W 2 SE 330th Ave

64.82 -- 310th Avenue (05487695, qw) 71N 24W 3 SW 310th Ave

69.09 -- 285th Avenue 71N 24W 6 NE 285th Ave

74.05 -- 260th Avenue 72N 25W 26 SW 260th Ave

79.73 -- U.S. Highway 69, Osceola 72N 25W 20 SW --

91.99 -- Drainage divide -- --

List of sites used to quantify main-channel slopes of White Breast Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

Figure 137. White Breast Creek, beginning at mouth in Marion County—Continued.
SUPPLEMENTAL DATA 209

List of sites used to quantify main-channel slopes of Whitewater Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 114 Mouth of Whitewater Creek 86N 1W 10 NE --

3.21 98.8 Jones-Dubuque County line 86N 1W 2 NE --

6.13 91.9 U.S. Highway 151 (05418200, low) 87N 1W 26 NE --

6.59 -- Simon Road 87N 1W 25 NW Simon Rd

15.09 -- North Cascade Road 87N 1W 1 C North Cascade Rd

18.34 16.8 East Pleasant Grove Road 88N 1W 36 NE E Pleasant Grove 

Rd

31.68 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Whitewater Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 138. Whitewater Creek, beginning at mouth in Jones County.
210 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Willow Creek—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 114 Mouth of Willow Creek, Des Moines Lobe landform 

region boundary

81N 32W 22 SE --

1.38 112 County Road F20 (05483400, low) 81N 32W 14 SW 130th St

5.56 -- State Highway 141 81N 32W 8 NE --

7.64 92.1 Guthrie-Greene County line 81N 32W 6 NE --

10.81 51.8 320th Street (05483380, low) 82N 32W 21 SW 320th St

15.61 -- County Road E57 82N 32W 7 NE 290th St

18.50 35.9 Greene-Carroll County line, County Road N58 83N 32W 30 SW A Ave

21.07 20.2 County Road E53 83N 33W 23 NE 250th St

28.74 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22

2

4

6

8

10

12

14

16

18

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Willow Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 139. Willow Creek, beginning at mouth in Guthrie County.
SUPPLEMENTAL DATA 211

List of sites used to quantify main-channel slopes of Willow Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 146 Mouth of Willow Creek 78N 44W 28 SE --

0.16 146 Abandoned road (06609620, low) 78N 44W 28 SE --

2.35 -- U.S. Highway 30, Missouri Valley 78N 44W 16 SE Erie St

7.70 129 County Road F50 (06609600, cont) 79N 43W 30 NE 260th St

11.82 118 235th Trail 79N 43W 10 C 235th Trl

13.42 -- State Highway 127 79N 43W 3 NW --

17.65 -- 180th Street 80N 43W 14 NW 180th St

23.69 67.0 Panora Avenue (06609580, low) 81N 42W 29 NE Panora Ave

28.04 53.9 Harrison-Monona County line, 340th Street 81N 42W 3 NW 340th St

32.94 29.1 State Highway 37 (06609560, csg) 82N 42W 11 S --

36.58 -- Monona-Crawford County line, 100th Street 83N 42W 36 NE 100th St

46.54 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

9

10

11

12

13

14

15

16

17

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Willow Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 140. Willow Creek, beginning at mouth in Harrison County.
212 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Willow Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 156 Mouth of Willow Creek, Le Mars 92N 45W 9 NW --

0.70 156 4th Avenue Northeast, Le Mars (06600160, low) 92N 45W 9 NE 4th Ave NE

2.79 -- Marble Avenue 92N 45W 11 NW Marble Ave

5.87 65.2 Nature Avenue (06600140, low) 93N 45W 36 W Nature Ave

9.68 61.4 140th Street 93N 44W 29 NW 140th St

13.61 53.2 120th Street 93N 44W 15 NE 120th St

17.33 38.3 Plymouth-Sioux County line 93N 44W 1 NW --

23.01 23.4 480th Street 94N 43W 19 NE 480th St

25.97 -- State Highway 10 94N 43W 8 NE --

36.57 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 2 4 6 8 10 12 14 16 18 20 22 24 26

7.0

7.1

7.2

7.3

7.4

7.5

7.6

7.7

7.8

7.9

8.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Willow Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 141. Willow Creek, beginning at mouth in Plymouth County.
SUPPLEMENTAL DATA 213

List of sites used to quantify main-channel slopes of the Winnebago River—Continued

River 

mile

Drainage 

area

(mi2

) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 700 Mouth of Winnebago River 95N 18W 14 SE --

1.32 -- 8th Street Southwest, Rockford (05460300, --) 95N 18W 15 NW 8th St SW

4.54 -- 200th Street 95N 18W 8 NW 200th St

7.00 -- Floyd-Cerro Gordo County line, County Road S70 96N 18W 31 SW Zinnia

9.55 677 Wren Avenue 96N 19W 35 N Wren Ave

13.61 -- U.S. Highway 18 96N 20W 20 SE --

14.38 -- Hydrologic Regions 1 and 2 boundary 96N 20W 20 NW --

17.81 632 State Highway 122, Mason City (05460220, --) 96N 20W 11 E 4th St SE

20.21 526 13th Street Northeast, Mason City (05459500, cont) 96N 20W 3 NW 13th St NE

105.82 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Winnebago River

[See section "Presentation of Curves" for explanation of list elements]

Figure 142. Winnebago River, beginning at mouth in Floyd County.
214 Main-Channel Slopes of Selected Streams in Iowa for Estimation of Flood-Frequency Discharges

List of sites used to quantify main-channel slopes of Wolf Creek—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 328 Mouth of Wolf Creek 87N 11W 19 C --

3.04 327 U.S. Highway 218, La Porte City (05464250, low) 87N 12W 25 SW 4th St

4.87 324 Black Hawk-Benton County line 86N 12W 35 S --

7.78 314 13th Avenue 86N 12W 10 SW 13th Ave

12.11 299 Benton-Tama County line, County Road V37 (05464220, 

cont)

86N 12W 19 NW V37

16.48 -- State Highway 21 86N 13W 22 N --

17.48 287 V Avenue (05464200, low) 86N 13W 21 NE V Ave

23.09 -- 150th Street 86N 13W 25 S 150th St

28.01 -- U.S. Highway 63, Traer 85N 14W 3 S Main St

34.64 -- County Road T69 85N 15W 11 S K Ave

39.71 122 County Road T55 85N 15W 17 NW Hwy T55

44.13 110 E Avenue 85N 16W 11 SW E Ave

50.54 64.2 Tama-Grundy, County line 86N 16W 31 SW --

51.95 63.2 M Avenue (05464100, low) 86N 17W 36 SW M Ave

57.88 46.6 J Avenue 86N 17W 33 SW J Ave

61.93 16.7 State Highway 14 86N 18W 23 NW --

71.82 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45 50 55 60 65

3

4

5

6

7

8

9

10

11

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of Wolf Creek

[See section "Presentation of Curves" for explanation of list elements]

Figure 143. Wolf Creek, beginning at mouth in Black Hawk County.
SUPPLEMENTAL DATA 215

List of sites used to quantify main-channel slopes of the Yellow River—Continued

River 

mile

Drainage 

area

(mi2) Site

Township, range, 

section, and 

subsection

Public address 

"911" street name

0.00 241 Mouth of Yellow River 96N 3W 34 SE --

0.07 -- State Highway 76 96N 3W 34 S --

9.73 221 County Road X36, Ion (05389000, cont) 96N 4W 24 SW Ion Rd

16.50 204 Old Sixteen Road 96N 4W 16 SE Old Sixteen Rd

20.13 179 Suttle Creek Road, Volney 96N 4W 18 SW Suttle Creek Rd

24.60 -- County road 96N 5W 15 SW --

26.64 115 Smithfield Drive 96N 5W 9 NW Smithfield Dr

30.86 78.7 Williams Creek Road 96N 6W 12 NE Williams Creek Rd

34.30 59.5 County Road W60 (05388800, low) 96N 6W 3NE Old Stage Rd

38.11 -- State Highway 51 96N 6W 8 SW --

40.69 35.4 Allamakee-Winneshiek County line 96N 6W 18 NW --

44.04 -- 130th Avenue 96N 7W 10 S 130th Ave

53.37 -- Drainage divide -- --

DISTANCE UPSTREAM FROM MOUTH, IN MILES

MAIN-CHANNEL SLOPE, IN FEET PER MILE

0 5 10 15 20 25 30 35 40 45

12

13

14

15

16

17

18

19

20

Curve adjusted 14.8 percent; see section

"Adjustment of Curves" for explanation

List of sites used to quantify main-channel slopes of the Yellow River

[See section "Presentation of Curves" for explanation of list elements]

Figure 144. Yellow River, beginning at mouth in Allamakee County.