-5

Estimating Monthly and 

Annual Streamflow 

Statistics at Ungaged 

Sites in Idaho

Water-Resources Investigations Report 01–4093 

U.S. Department of the Interior

U.S. Geological Survey

U.S. DEPARTMENT

OF AGRICULTURE,

FOREST SERVICE
This page intentionally left blank -4
-3

Estimating Monthly and 

Annual Streamflow 

Statistics at Ungaged 

Sites in Idaho

By Jon E. Hortness and Charles Berenbrock

Water-Resources Investigations Report 01–4093

Prepared in cooperation with

U.S. Department of Agriculture,

Forest Service

Boise, Idaho

2001
-2

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of firm, trade, and brand names in this report is for

identification purposes only and does not constitute 

endorsement by the U.S. Government.

Additional information can be 

obtained from:

District Chief

U.S. Geological Survey

230 Collins Road

Boise, ID 83702-4520

http://idaho.usgs.gov

Copies of this report can be 

purchased from:

U.S. Geological Survey

Information Services

Box 25286

Federal Center

Denver, CO 80225

e-mail: infoservices@usgs.gov

Copies of this report also are 

available in PDF format, which can 

be viewed using Adobe Acrobat 

Reader, at URL:

http://idaho.usgs.gov/public/

reports.html 
Contents -1

CONTENTS

Contents

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

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

Purpose and scope............................................................................................................................................................. 1

Description of study area .................................................................................................................................................. 1

Previous investigations............................................................................................................................................................. 4

Estimating streamflow statistics using basin characteristics.................................................................................................... 4

Streamflow data ................................................................................................................................................................ 4

Basin characteristics.......................................................................................................................................................... 5

Determination of regions .................................................................................................................................................. 6

Estimation method ............................................................................................................................................................ 6

Reliability and limitations........................................................................................................................................................ 8

Application of method.............................................................................................................................................................. 9

Example 1 ......................................................................................................................................................................... 9

Example 2 ......................................................................................................................................................................... 10

Example 3 ......................................................................................................................................................................... 10

Summary .................................................................................................................................................................................. 10

References cited ....................................................................................................................................................................... 11

Appendices

A. Selected streamflow-gaging stations and periods of record used in regression analysis............................................. 25

B. Monthly and annual streamflow statistics for selected streamflow-gaging stations.................................................... 28

C. Basin characteristics for selected streamflow-gaging stations..................................................................................... 34

FIGURES

1. Map showing location of streamflow-gaging stations used in regional regression analysis, Idaho ............................. 2

2. Map showing location of regions defined for use in regional regression analysis, Idaho ............................................ 7

3. Graph showing joint distribution of mean basin elevation and mean precipitation for gaged sites in 

region 2, Idaho .............................................................................................................................................................. 9

TABLES

1. Selected data sources used to obtain basin characteristics for regional regression analysis......................................... 5

2. Description of selected basin characteristics used in final estimating equations.......................................................... 5

3. Results of regional regression analysis based on data from 13 gaging stations for region 1........................................ 15

4. Results of regional regression analysis based on data from 26 gaging stations for region 2........................................ 16

5. Results of regional regression analysis based on data from 9 gaging stations for region 3.......................................... 17

6. Results of regional regression analysis based on data from 43 gaging stations for region 4........................................ 18

7.

10. Results of regional regression analysis based on data from 31 gaging stations for region 8........................................ 22

Results of regional regression analysis based on data from 30 gaging stations for region 5........................................ 19

11. Maximum and minimum values of basin characteristics used in regional regression analysis.................................... 8

8. Results of regional regression analysis based on data from 23 gaging stations for region 6........................................ 20

9. Results of regional regression analysis based on data from 25 gaging stations for region 7........................................ 21

iii
Contents 0

CONVERSION FACTORS, VERTICAL DATUM, AND WATER YEAR

Multiply By To obtain

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

foot (ft) 0.3048 meter

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

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

square mile (mi2) 2.590 square kilometer

Sea level: In this report, sea level refers to the North American Vertical Datum of 1988 (NAVD of 1988) a vertical control datum 

established by the minimum-constraint adjustment of Canadian-Mexican-United States leveling observations and held fixed at Father 

Point/Rimouski, Quebec, Canada.

Water year: In U.S. Geological Survey reports dealing with surface-water supply, a water year is the 12-month period, October 1 through 

September 30. The water year is designated by the calendar year in which it ends; thus, the water year ending September 30, 1999, is called 

the 1999 water year.

iv Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Introduction 1

ABSTRACT

Updated monthly and annual streamflow information for the many ungaged streams throughout Idaho is needed to assist planners and managers with issues regarding fish and wildlife, water 

rights, and other land and water uses. To provide 

this information, the U.S. Geological Survey used 

a multiple-regression analysis to develop equations for estimating daily mean discharge exceeded 80, 50, and 20 percent of the time each month 

(80-, 50-, and 20-percent monthly exceedances) 

and mean annual discharge values at ungaged sites. 

The analysis produced estimating equations that 

relate specific streamflow statistics to basin characteristics. The standard errors of estimate, in log10, 

of the final estimating equations ranged from a 

minimum of 0.072 (+18.1 to -15.3 percent) to a 

maximum of 0.498 (+214.8 to -68.2 percent).

The estimating equations might not yield reliable results for sites with basin characteristic values outside of the range of values used to develop 

the equations. The equations also are not applicable for regulated streams or those that exhibit significant gains and (or) losses as a result of spring 

flow, seepage through permeable streambeds, or 

irrigation diversions.

The equations generally were more reliable 

for estimating the high monthly streamflow statistics (20-percent exceedances) than for estimating 

the low streamflow statistics (80-percent exceedances) in each region and all streamflow statistics 

in regions where annual streamflow is relatively 

low.

INTRODUCTION

Introduction

Extreme variability in streamflow across the State 

of Idaho can complicate decision-making processes for 

planners and managers who frequently deal with issues 

regarding fish and wildlife, water rights, and other 

land and water uses. Monthly and annual streamflow 

information is needed to assist these planners and 

managers in making informed decisions. This information is available at sites where long-term gaging stations are located; however, many streams in Idaho are 

ungaged.

Kjelstrom (1998) outlined methods for estimating monthly exceedance discharge values at ungaged 

sites in the Salmon and Clearwater River Basins in 

central Idaho, and Horn (1988) developed estimates 

for mean annual discharge at ungaged sites across 

Idaho. However, estimates of monthly exceedance values are needed throughout the State, and Horn s mean 

annual estimates were based on data only through 

1977. Because of the need for updated monthly and 

annual discharge information at ungaged sites throughout Idaho, the U.S. Geological Survey (USGS), in 

cooperation with the U.S. Forest Service, began a 

study to develop techniques for estimating long-term 

daily mean discharge exceeded 80, 50, and 20 percent 

of the time each month (80-, 50-, and 20-percent 

exceedance values) and mean annual discharge.

Purpose and Scope

This report summarizes the techniques used 

to estimate various monthly and annual streamflow 

statistics using regional regression equations and 

describes the associated reliability and limitations. 

Equations were developed to estimate the 80-, 50-, and 

20-percent monthly exceedance discharges and the 

mean annual discharge at ungaged, unregulated sites. 

Standard errors of estimate were calculated to help 

predict the reliability and accuracy of each equation.

Description of Study Area

The study area (fig. 1) includes the entire State 

of Idaho and areas of adjacent States where particular 

drainage basins cross over State boundaries. The adjaEstimating Monthly and Annual Streamflow Statistics at 

Ungaged Sites in Idaho

By Jon E. Hortness and Charles Berenbrock
Kootenai

River Priest

River

Spokane

River

St

River

Joe

Pend

Oreille

Lake

Coeur

d'Alene

Lake

Fork

Clark

Bitterroot River

Clearwater

Lochsa

Selway

River

River River Dworshak Reservoir

Salmon

River

Snake

River

Grande

Ronde

Sandpoint

Coeur

d'Alene

Lewiston

3 4

5

11 10

8 7

2 1

16

14

15

6

9

12

13

40

32

23 22

25 21 20

24

26 27 28

31

30

29 19

39

38 42

47 44

45, 46

43

41

48 89

88 87

35

34

36

37

33

18

94

93

17

92 84

85

76

75

90

91

77

79

82 83

81

80

78

86

IDAHO

WASHINGTON

OREGON

NEVADA 

Figure 1. Location of streamflow-gaging stations used in regional regression analysis, Idaho.

2 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Introduction 3 0 

20 

0 40 20 

Base from U.S. Geological Survey digital data,1:2,000,000, 1999;Transverse Mercator projectionFactor at central meridian: 0.99960Longitude of central meridian: -114° 00'

Latitude of origin: 42° 00'

False easting (meters): 500,000.0False northing (meters): 100,000.0

River

Weiser

River

Lemhi

River

Salmon

River

River

Snake

Boise

River

River

Malheur

River

Owyhee

River

Bruneau

Snake

River

Raft

River

Portneuf

R

B

H

Snake

Bear

American Falls

Reservoir

River

Lost

Big

River Wood

Big

Salmon

Lucky

Peak

Lake

Salmon

Boise

Twin

Falls

Pocatello

Id

F

124

123

140

139

141

143

117 113

118

116 119

114

59 104

60

58

57

71 70

63

72

142

144

74 121

120

73 115

55

68

67 69

169

62

61

64

66

65

122

138

112 109 135

107

111 108

110 133 137

134

129

127

128

1

126

132

131 130 106

136 105

95

103

49 53 50

56

54

51

168

52

102

99

100

96

98

97

101

164

163 165

151

162

161

160

158 157

154

167

1

145

155

156

152

149 150

166

159

146

148

147 
4 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho

cent States partially included in the study area are 

Washington, Oregon, Nevada, Utah, Wyoming, and 

Montana. The northern and central parts of the area are 

composed mainly of rugged, mountainous terrain; 

broad plains and mildly sloping valleys and hills predominate in the south. Geologic features across the 

study area consist of sedimentary, igneous, and metamorphic rocks ranging in age from Precambrian to 

Holocene (Bond, 1978). The granitic Idaho batholith is 

the major structural feature in the central part of the 

study area, and basalt covers much of the southern and 

western parts (Ross and Savage, 1967).

Most precipitation in the study area results from 

storms moving inland from the Pacific Ocean. The 

amount of precipitation varies widely throughout the 

area and is greatly affected by topography. Precipitation ranges from less than 10 in. per year on the Snake 

River Plain in south-central Idaho to 60 to 70 in. per 

year in the central mountains of Idaho (Molnau, 1995). 

The most significant amounts of precipitation are a 

direct result of orographic effects and occur mainly in 

the winter months. Spring and summer thunderstorms 

in the southern part of the study area sometimes produce large amounts of precipitation. Resulting streamflow varies geographically and seasonally and can be 

affected by land use and vegetation. During much of 

the year, streamflow in most unregulated streams in 

the study area is minimal base flow; during April, 

May, June, and July, streamflow is significantly 

higher, primarily as a result of snowmelt. Occasionally during the winter months, large frontal systems 

carrying warmer air release moisture as rain on the 

snowpack and frozen ground, which results in rapid 

snowmelt and high runoff rates, particularly at elevations less than 6,000 ft above sea level (National Oceanic and Atmospheric Administration, 1971).

PREVIOUS INVESTIGATIONS

Two previous studies dealt with developing 

regional regression equations for use in estimating 

mean annual discharges at ungaged sites in Idaho. 

Quillian and Harenberg (1982) divided the State into 

nine regions and developed separate regression equations for each. The following basin characteristics 

were used in one or more of their equations: basin 

area, mean annual precipitation, percent forest cover, 

longitude of the gaging station, and mean basin elevation. Using streamflow data through 1977, Horn 

(1988) developed a method for estimating mean 

annual discharges in an effort to define the drought 

characteristics of streams across Idaho. He divided the 

State into two regions and used basin area, mean 

annual precipitation, and percent forest cover to estimate streamflow statistics.

Kjelstrom (1998) developed a method for estimating the 20-, 50-, and 80-percent monthly exceedance 

discharge values for the Salmon and Clearwater River 

Basins in central Idaho, using the mean monthly discharge and a multiplication factor. This method pertains only to the approximately 1,050 subbasins identified by Lipscomb (1998), who estimated the mean 

monthly discharges for each subbasin by apportioning 

mean annual discharges into monthly increments on 

the basis of records from gaging stations selected as 

being characteristic of the subbasin. Lipscomb estimated the mean annual discharges by using the 

regional regression equations developed by Quillian 

and Harenberg (1982).

ESTIMATING STREAMFLOW STATISTICS USING 

BASIN CHARACTERISTICS

Estimating Streamflow Statistics Using Basin Characteristics

Using multiple-regression equations to relate 

streamflow statistics to various basin and climatic variables (basin characteristics) is a common method for 

estimating streamflow at ungaged sites. Once the 

equations have been developed, streamflow statistics 

at ungaged sites can be estimated by determining the 

necessary basin characteristics and inserting that information into the regression equations. In this study, 

regression equations were developed for use in estimating 80-, 50-, and 20-percent monthly exceedance 

discharges (Q.80, Q.50, and Q.20) and the mean 

annual discharge (Qa). These statistics are commonly 

used for analyzing streamflow.

Streamflow Data

Daily mean discharge values from 200 continuousrecord gaging stations were used to develop the regression equations (U.S. Geological Survey, 1955-2000). 

Each gaging station had at least 10 years of record 

through water year 1999. Gaging stations located on 

streams where flows are regulated, where diversions 

significantly affect flows, or where significant dis-
Estimating Streamflow Statistics Using Basin Characteristics 5

charge from springs augments streamflow were not 

included in the analysis. The locations of all gaging 

stations used in the analysis are shown in figure 1. The 

map numbers that correspond to the gaging stations 

shown in figure 1, the station identification number, 

station name, and period of record for each are listed 

in appendix A. Monthly and annual streamflow statistics computed for each station are listed in appendix B.

Basin Characteristics

More than 50 separate basin characteristics were 

obtained for each of the 200 gaging stations included in 

the study. All basin characteristics were obtained using 

Arc Macro Language programs written for Arc/Info 

(Environmental Systems Research Institute, Inc., 1999). 

These programs generated the basin characteristic values from the datasets listed in table 1. Several basin 

characteristics were removed from consideration after 

correlation plots of the data were reviewed. Generally, 

if two basin characteristics correlated well, the one that 

was the least difficult to obtain was kept and the other 

was removed. Other characteristics were removed because of missing data or difficulty in obtaining the data. 

By following this process, nine standard basin characteristics were retained for use in the multiple-regression analysis. Of the nine characteristics used in the 

analysis, eight were included in at least one of the final 

equations. These eight standard characteristics were: 

drainage area (A), mean basin elevation (E), basin 

relief (BR), slopes greater than 30 percent (S30), mean 

annual precipitation (P), forested area (F), basin slope 

(BS), and main channel slope (MCS). Basin azimuth 

also was included in the analysis but was not used in 

any of the final equations. Detailed information on the 

eight basin characteristics used in the equations is 

listed in table 2, and basin characteristic values obtained for each gaging station are listed in appendix C. 

One percent was added to the measured values for S30 

Table 1. Selected data sources used to obtain basin characteristics 

for regional regression analysis

[Multiply meter by 3.281 to obtain foot; multiply kilometer (km) by 

0.6214 to obtain mile]

Dataset name Source description

National Elevation 

Dataset (NED)

Basin characteristics were calculated using 

30-meter resolution digital elevation data 

(http://gisdata.usgs.gov/ned/)

National Elevation 

Dataset Hydrologic 

Derivatives (NED-H)

Hydrologic derivatives of NED data were

developed using procedures similar to those in 

Stage 1 processing, using a custom projection 

for Idaho (http://edcnts12.cr.usgs.gov/ned-h/

about/Stage1.html)

National Land Cover 

Dataset (NLCD)

Vogelmann, J.E., Sohl, T.L., Campbell, P.V., 

and Shaw, D.M., 1998, Regional land cover 

characterization using Landsat Thematic Mapper data and ancillary data sources: Environmental Monitoring and Assessment v. 51, 

p. 415–428 

(http://edcwww.cr.usgs.gov/programs/lccp)

Idaho map of mean 

annual precipitation

Molnau, M., 1995, Mean annual precipitation, 

1961–1990, Idaho: Moscow, University of 

Idaho, Agricultural Engineering Department, 

State Climate Program, scale 1:1,000,000 

(http://snow.ag.uidaho.edu/Climate/

reports.html)

Western United States 

average monthly or 

annual precipitation

Daly, C., and Taylor, G., 1998, Western United 

States average monthly or annual precipitation, 

1961–90, Oregon: Portland, Water and Climate 

Center of the Natural Resources Conservation 

Service, grid-cell resolution 4 km 

(http://www.ocs.orst.edu/prism/prism_new.html)

Table 2. Description of selected basin characteristics used in 

final estimating equations

[Multiply meter by 3.281 to obtain foot; multiply kilometer (km) by 

0.6214 to obtain mile]

Basin characteristic 

and symbol Description and estimating technique

Drainage area (A) Area of the basin that contributes surface runoff, in square miles; estimated using Arc/Info 

Grid with 30-meter resolution digital elevation 

models (DEMs)

Mean basin elevation 

(E)

Mean elevation of the basin, in feet above sea 

level; estimated using Arc/Info Grid and averaging elevations using 30-meter resolution DEMs

Basin relief (BR) Maximum relief of the basin, in feet; estimated 

using Arc/Info Grid by subtracting the lowest 

elevation in the basin from the highest using 

30-meter resolution DEMs

Slopes greater than 

30 percent (S30)

Area of the basin with slopes greater than 30 

percent, in percent of drainage area; estimated 

using the "average maximum technique" in 

Arc/Info Grid with 30-meter resolution DEMs

Mean annual precipitation (P)Mean annual precipitation over the entire drainage area, in inches; estimated using Arc/Info 

Grid with a combination of 500-meter (within 

Idaho) and 4-km (outside of Idaho) resolution 

precipitation grids

Forested area (F) Area of the basin containing forest, in percent 

of drainage area; estimated using Arc/Info Grid 

with a 37-meter resolution land cover grid

Basin slope (BS) Average slope of the basin, in percent; estimated using the "average maximum technique" 

in Arc/Info Grid with 30-meter resolution 

DEMs

Main channel slope 

(MCS)

Slope of the main channel from basin outlet to 

basin divide, in feet per mile; estimated by 

determining the difference in elevations at 

points 85 and 10 percent of the main channel 

upstream from the outlet, then dividing by 

0.75 times the main channel length
6 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho

and F to ensure that zero values, which cannot be transformed, would not result at any site. Measured values 

for E and BR were divided by 1,000 to allow for more 

convenient coefficients in the final equations. The variables that represent the adjusted values are denoted 

with an asterisk in the estimating equations (S30*, F*, 

E*, and BR*).

Determination of Regions

In regional streamflow frequency analyses, 

attempts are made to define regions that are hydrologically homogeneous in terms of the characteristics 

being studied (Haan, 1977). Thus, a graphical cluster 

analysis was performed using the basin characteristics 

obtained for the 200 gaging stations included in the 

study. This analysis revealed several unique groupings of basin characteristics across the State. The final 

groupings were based on mean basin elevation, basin 

slope, percentage of basin covered by forest, and mean 

annual precipitation. On the basis of the cluster analysis and the resulting final groupings of basin characteristics, the State was divided into eight regions (fig. 2) 

and separate equations were developed for each. The 

region boundaries were determined on the basis of the 

following factors: (1) grouping of similar basin characteristics that were revealed in the cluster analysis; (2) 

geographic features, such as large mountain ranges or 

breaks between mountains and plains; and (3) engineering judgment based on general knowledge of the 

area. A part of the area commonly referred to as the 

eastern Snake River Plain was excluded from the 

analysis for several reasons: (1) Most of the streams 

in this region either are regulated or are significantly 

affected by irrigation diversions, (2) several springs 

with extremely large discharges add significant flow 

to streams in the region, and (3) the lithology of the 

area consists mainly of layered basalts that exhibit 

extremely high rates of infiltration. The effects of 

these features on the hydrology of the area cannot be 

characterized by a regional regression approach.

Estimation Method

For use in the multiple-regression analysis, all 

streamflow and basin characteristic data were transformed to base-10 logarithms. This transformation was 

performed to obtain a linear regression model and to 

achieve equal variance about the regression line. The 

linear regression model makes it possible to perform 

an ordinary least-squares (OLS) analysis from which 

the regression constants can be computed. Equal variance about the regression line satisfies a basic assumption of regression methods, which states that the distribution of errors about the regression line is normal and 

constant throughout the range (Riggs, 1968).

A statistical computer software program, Statit 

(Statware, Inc., 1992), was used to derive the estimating equations in the following linear form:

, (1)

where Q (dependent variable) is the desired monthly 

or annual streamflow statistic, in cubic feet per second 

(80-, 50-, or 20-percent exceedance or mean annual discharge); a is the multiple-regression constant; b1, b2, ... 

bn are the regression coefficients; and B, C, ... N are 

the values of the required basin characteristics (independent variables).

The antilogarithms of all values in equation 1 

resulted in the following nonlinear form of the estimating equation:

. (2)

Statit uses OLS regression techniques to determine the best variables for use in the regression equations. All possible combinations of variables were analyzed and the best combinations were chosen on the 

basis of the standard error of estimate (SEE). The SEE 

is a measure of the fit of the regression equation to the 

observed data. The equation with the smallest SEE 

results in the narrowest confidence limits and thus, 

generally, the most reliable estimating equation (Haan, 

1977).

For any given month, the basin characteristics that 

resulted in the best overall fit (smallest average SEE) 

for all of the equations were used as the independent 

variables in all three estimating equations. This ensures that the correlation structure between the streamflow statistics for each month is preserved, which 

results in stable and consistent estimates of the statistics (Haan, 1977). Estimating equations were developed for each region and are listed in tables 3 through 

10 (back of report), along with the associated errors 

for each. The SEEs presented in log10 represent the 

error of the transformed equations. The SEEs presented in a percentage range represent the error of the 

logQ a = log + + ++ b1logB b2logC ... bn1

Q aBb1 = Cb2...Nbn
Estimating Streamflow Statistics Using Basin Characteristics 7







 

American Falls Reservoir

Bear

Lake

Pend Oreille

Lake

Coeur

d'Alene

Lake

Idaho

Falls

Lewiston

Salmon

Sandpoint

Coeur

d'Alene

Boise

Twin

Falls

Pocatello

Boundary of eastern

Snake River Plain

2

7

6

8

4

3

1

5

0 40 20 60 100 MILES 80

0 40 20 60 100 KILOMETERS 80

Base from U.S. Geological Survey digital data, 1:2,000,000, 1999;

Regions based on Hydrologic Unit Boundaries, 1:2,000,000, 1999;

Transverse Mercator projection

Factor at central meridian: 0.99960

Longitude of central meridian: -114° 00'

Latitude of origin: 42° 00'

False easting (meters): 500,000.0

False northing (meters): 100,000.0

Figure 2. Location of regions defined for use in regional regression analysis, Idaho.

EXPLANATION

Region and identification number

 for which specific regression

 equations were developed

 (tables 3 through 10)

Undefined area

2
8 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho

final, untransformed equations based on equations presented by Riggs (1968).

RELIABILITY AND LIMITATIONS

Reliability and Limitations

The SEEs for the equations, in log10, over all 

eight regions ranged from a minimum of 0.072 for 

Qa in region 3 to a maximum of 0.498 for August 

(Q.80) in region 7. The standard errors of estimate for 

these streamflow statistics exhibited a minimum range 

of +18.1 to -15.3 percent and a maximum range of 

+214.8 to -68.2 percent. These error values represent 

the general reliability of the estimating equations; 

however, other factors could limit the applicability 

of the equations.

Because this method is based on a regression 

analysis, the equations might not be reliable for sites 

where the basin characteristics are outside of the range 

of characteristics that were used to develop the equations (table 11). In addition, using basin characteristic 

values near their extremes (maximum or minimum, 

table 11) might result in unreliable and erroneous estimates. Figure 3 shows a "cloud of common values" for

two of the four basin characteristics used in equations 

for February in region 2. If the minimum value for 

mean annual precipitation and the maximum value for 

mean basin elevation were used, this combination 

would plot outside of the "cloud of common values"

and, thus, the equations might result in unreliable estimates. Generating basin characteristic values by using 

datasets or algorithms other than those described in 

this study will also result in estimates of unknown reliability. The standard errors of estimate for each equation are applicable only if the datasets presented in 

table 1 are used to obtain the required basin characteristics and the specific algorithms described in table 2 

Table 11. Maximum and minimum values of basin characteristics used in regional regression analysis

[A, drainage area, in square miles; E, mean basin elevation, in feet above sea level; BR, basin relief, in feet; S30, 

slopes greater than 30 percent, in percent of drainage area; P, mean annual precipitation, in inches; F, forested 

area, in percent of drainage area; BS, basin slope, in percent; MCS, main channel slope, in feet per mile]

A E BR S30 P F BS MCS

Region 1

maximum . . . . . . . . 1,011.0 5,347.3 5,866.9 81.4 54.3 94.5 46.4 265.6

minimum. . . . . . . . . 12.5 2,397.7 2,230.6 9.4 25.1 54.6 12.2 11.1

Region 2

maximum . . . . . . . . 1,913.1 6,649.7 7,789.6 89.6 60.9 95.1 58.8 466.2

minimum. . . . . . . . . 3.0 3,465.5 1,643.9 31.7 29.6 50.3 23.8 18.5

Region 3

maximum . . . . . . . . 674.9 3,752.2 5,098.9 57.5 30.1 63.4 35.4 139.3

minimum. . . . . . . . . 17.6 2,647.1 1,442.8 0.1 19.3 0.6 10.0 11.8

Region 4

maximum . . . . . . . . 13,418.3 7,461.3 11,152.1 87.0 64.6 93.0 57.2 328.9

minimum. . . . . . . . . 4.0 3,528.6 1,821.4 17.7 15.9 4.8 18.7 17.2

Region 5

maximum . . . . . . . . 12,228.0 8,204.0 10,701.3 77.8 44.5 88.7 46.7 213.0

minimum. . . . . . . . . 19.3 6,171.1 2,743.5 24.7 22.4 22.4 20.2 19.9

Region 6

maximum . . . . . . . . 6,236.7 9,461.0 9,419.7 94.2 32.0 80.2 66.2 869.9

minimum. . . . . . . . . 6.4 6,258.1 3,015.2 7.5 15.3 14.5 8.6 18.0

Region 7

maximum . . . . . . . . 535.3 7,603.0 5,683.3 55.2 29.1 38.9 35.3 372.8

minimum. . . . . . . . . 12.5 2,984.4 1,178.3 0.0 8.2 0.0 1.7 18.4

Region 8

maximum . . . . . . . . 874.8 8,951.0 6,232.1 86.6 56.0 93.9 49.7 413.0

minimum. . . . . . . . . 16.3 5,691.9 1,100.5 1.2 14.2 2.3 6.1 24.7
Application of Method 9

are used; however, software programs other than 

Arc/Info can be used.

The estimating equations are not applicable for 

streams that exhibit significant gains and (or) losses as 

a result of spring flow or seepage through highly permeable streambeds. The equations also are not applicable for streams affected by irrigation diversions or 

large dams that regulate streamflow. The Boise River 

downstream from Lucky Peak Lake, the Clearwater 

River downstream from Dworshak Reservoir, and the 

entire Snake River are examples of stream reaches 

within the study area for which the estimating equations are not applicable.

In general, the equations are more reliable (lower 

standard errors of estimate) for estimating the high 

streamflow statistics (20-percent exceedance) than 

for estimating the low streamflow statistics (80-percent exceedance) in any given month. This finding is 

consistent with that of Riggs (1972), who stated that 

low streamflows are largely affected by localized geology that cannot be quantified easily. Parrett and Cartier (1990) also determined that equations developed 

for western Montana were generally more reliable for 

estimating high streamflow statistics.

Although the SEEs of the estimating equations 

for regions 6 and 7 generally were significantly larger 

than those for other regions, the natural variability of 

streamflows in regions 6 and 7 is also significantly 

greater than in the other regions as a result of more 

sporadic and generally less precipitation (Molnau, 

1995). Prediction of streamflow statistics that have a 

high degree of variability will always have more 

uncertainty than prediction of statistics that are more 

stable.

APPLICATION OF METHOD

Application of Method

Examples of how to use the equations for estimating monthly or annual streamflow statistics are given 

in the following paragraphs. The third example 

addresses the situation where the drainage area of a 

specific site encompasses parts of two separate 

regions.

Example 1

Estimates of Q.80, Q.50, and Q.20 for the month 

of June and Qa are required for a stream location in 

region 5. The required basin characteristics for region 

5 equations were determined to be the following: A, 

480.5 mi2; BS, 30.2 percent; S30, 42.8 percent; and F, 

71.0 percent. For use in the equations, 1 percent is 

added to the values for S30 and F.

Q.80 = 2.22x10-4 A 0.810 BS 10.7 S30* -7.89 F* 0.993 (3)

Q.80 = 2.22x10-4

 (480.5)0.810 (30.2)10.7 (43.8)-7.89 (72.0)0.993

Q.80 = 1,770 ft3/s

Q.50 = 5.12x10-4 A 0.832 BS 9.84 S30* -7.28 F* 1.04 (4)

Q.50 = 5.12x10-4

 (480.5)0.832 (30.2)9.84 (43.8)-7.28 (72.0)1.04

Q.50 = 3,060 ft3/s

Q.20 = 1.27x10-3 A 0.824 BS 9.37 S30* -6.88 F* 0.942 (5)

Q.20 = 1.27x10-3

 (480.5)0.824 (30.2)9.37 (43.8)-6.88 (72.0)0.942

Q.20 = 4,340 ft3/s

Qa = 1.07x10-2 A 0.831 BS 7.25 S30* -5.42 F* 0.448 (6)

Qa = 1.07x10-2

 (480.5)0.831 (30.2)7.25 (43.8)-5.42 (72.0)0.448

Qa = 838 ft3/s

The predicted range of the actual values for each 

streamflow statistic, based on the range of the standard 

errors of estimate given in table 7, is as follows:

MEAN BASIN ELEVATION,

IN THOUSANDS OF FEET ABOVE SEA LEVEL

MEAN ANNUAL

PRECIPITATION, IN INCHES

Figure 3. Joint distribution of mean basin elevation and mean

precipitation for gaged sites in region 2, Idaho.

100

80

60

40

20

0

0 2 4 6 8 10

Cloud of

common values
10 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho

Q.80--2,620 to 1,200 ft3/s (+48.0 to -32.4 percent)

Q.50--4,160 to 2,250 ft3/s (+36.1 to -26.5 percent)

Q.20--5,880 to 3,200 ft3/s (+35.5 to -26.2 percent)

Qa--1,150 to 608 ft3/s (+37.7 to -27.4 percent)

Example 2

Estimates of Q.80, Q.50, and Q.20 for the month 

of April and Qa are required for a stream location in 

region 2. The required basin characteristics for region 

2 equations were determined to be the following: A, 

923.0 mi2; E, 6,220 ft; F, 82.1 percent; and P, 46.5 in. 

For use in the equations, the value for E is divided by 

1,000, and 1 percent is added to the value for F.

Q.80 = 1.21x10-8 A0.999 E* -0.783 F* 2.45 P 2.46 (7)

Q.80 = 1.21x10

-8

 (923.0)

0.999 (6.22)

-0.783 (83.1)

2.45 (46.5)2.46

Q.80 = 1,690 ft3/s

Q.50 = 1.11x10-7 A0.993 E* -0.696 F* 2.17 P 2.30 (8)

Q.50 = 1.11x10-7

 (923.0)0.993 (6.22)-0.696 (83.1)2.17 (46.5)2.30

Q.50 = 2,740 ft3/s

Q.20 = 1.26x10-6 A0.978 E* -0.480 F* 1.87 P 2.10 (9)

Q.20 = 1.26x10-6

 (923.0)0.978 (6.22)-0.480 (83.1)1.87 (46.5)2.10

Q.20 = 5,140 ft3/s

Qa = 5.14x10-6 A0.986 F* 0.942 P 2.33 (10)

Qa = 5.14x10-6

 (923.0)0.986 (83.1)0.942 (46.5)2.33

Qa = 2,130 ft3/s

The predicted range of the actual values for each 

streamflow statistic, based on the range of the standard 

errors of estimate given in table 4, is as follows:

Q.80--2,750 to 1,040 ft3/s (+62.9 to -38.6 percent)

Q.50--4,450 to 1,690 ft3/s (+62.4 to -38.4 percent)

Q.20--8,130 to 3,250 ft3/s (+58.2 to -36.8 percent)

Qa--3,330 to 1,360 ft3/s (+56.5 to -36.1 percent)

Example 3

An estimate of Q.50 for the month of August is 

required for a stream location in region 4 with a drainage basin encompassing parts of regions 4 and 5. The 

method for handling sites with parts of the drainage 

area in two regions is as follows: (1) Calculate values 

for the entire basin by using equations from the first 

region, (2) calculate values for the entire basin by 

using equations from the second region, and (3) average the two values on the basis of the proportion of 

drainage area in each region (Sando, 1998). The 

required basin characteristics for region 4 and 5 equations were determined to be the following: A, 853.0 

mi2; BS, 38.5 percent; P, 39.4 in.; S30, 61.2 percent; 

and F, 42.2 percent. The part of the drainage area 

located in region 4 covers 622.0 mi2 and the part in 

region 5 covers 231.0 mi2

. For use in the equations, 1 

percent is added to the values for S30 and F.

(1) REGION 4 EQUATIONS

Q.50 = 2.92x10-6 A1.09 BS 1.14 P 1.95 (11)

Q.50 = 2.92x10-6

 (853.0)1.09 (38.5)1.14 (39.4)1.95

Q.50 = 379 ft3

/s

(2) REGION 5 EQUATIONS

Q.50 = 2.52x10-4 A 0.865 BS 8.06 S30* -5.89 F* 0.848 (12)

Q.50 = 2.52x10-4

 (853.0)0.865 (38.5)8.06 (62.2)-5.89 (43.2)0.848

Q.50 = 344 ft3

/s

(3) AREA-WEIGHTED AVERAGE OF THE VALUES

Q.50 = 379 ft3/s (622.0 / 853.0) + 344 ft3/s (231.0 / 853.0) (13)

Q.50 = 370 ft3

/s

SUMMARY

Equations for estimating monthly exceedance 

(80-, 50-, and 20-percent) and mean annual discharge 

values at ungaged sites were developed using a multiple-regression analysis. The analysis related streamflow to various basin characteristics. Nine basin characteristics were tested in the final analysis, and eight 

of these characteristics were used in one or more of the 

final estimating equations. The standard errors of estimate for these equations, in log10, ranged from a minimum of 0.072 for mean annual discharge in region 3 to 

a maximum of 0.498 for August (Q.80) in region 7. 

The standard errors of estimate for these streamflow 

statistics exhibited a minimum range of +18.1 to -15.3 
Application of Method 11

percent and a maximum range of +214.8 to -68.2 percent. The estimating equations might not yield reliable 

results for sites with basin characteristic values outside of the range of values used to develop the equations. The equations also are not applicable for regulated streams or those affected by significant gains and 

(or) losses due to spring flow, seepage through highly 

permeable streambeds, or irrigation diversions.

The equations were generally more reliable for 

estimating the high streamflow statistics (20-percent 

exceedance) than for estimating the low streamflow 

statistics (80-percent exceedance) in any given month. 

This is likely because lower streamflow statistics are 

more difficult to estimate, owing to effects of localized geology. The standard errors of estimate of equations for regions 6 and 7 generally were significantly 

larger than those for other regions. This could be a 

result of the natural variability of streamflows in 

regions 6 and 7, which is also significantly greater 

than in other regions because precipitation is generally minimal and sporadic.

REFERENCES CITED

Bond, J.G., 1978, Geologic map of Idaho: Moscow, 

Idaho Bureau of Mines and Geology, 1 sheet, 

scale 1:500,000.

Environmental Systems Research Institute, Inc., 1999, 

Getting started with Arc/Info: Redlands, Calif., 

Environmental Systems Research Institute, Inc., 

230 p.

Haan, C.T., 1977, Statistical methods in hydrology: 

Ames, Iowa State University Press, 378 p.

Horn, D.R., 1988, Annual flow statistics for ungaged 

streams in Idaho: American Society of Civil Engineers, Journal of Irrigation and Drainage Engineering, v. 114, no. 3, p. 463-474.

Kjelstrom, L.C., 1998, Methods for estimating selected 

flow-duration and flood-frequency characteristics 

at ungaged sites in central Idaho: U.S. Geological 

Survey Water-Resources Investigations Report 

94-4120, 10 p.

Lipscomb, S.W., 1998, Hydrologic classification and 

estimation of basin and hydrologic characteristics 

of subbasins in central Idaho: U.S. Geological Survey Professional Paper 1604, 49 p.

Molnau, M., 1995, Mean annual precipitation, 1961-

1990, Idaho: Moscow, University of Idaho, Agricultural Engineering Department, State Climate 

Program, scale 1:1,000,000. Also available at URL 

http://snow.ag.uidaho.edu/Climate/reports.html

National Oceanic and Atmospheric Administration, 

1971, Climates of the states, climate of Idaho, in

Climatography of the United States: Silver Spring, 

Md., no. 60-10, 18 p. 

Parrett, Charles, and Cartier, K.D., 1990, Methods for 

estimating monthly streamflow characteristics at 

ungaged sites in western Montana: U.S. Geological 

Survey Water-Supply Paper 2365, 30 p.

Quillian, E.W., and Harenberg, W.A., 1982, An evaluation of Idaho stream-gaging networks: U.S. Geological Survey Open-File Report 82-865, 57 p.

Riggs, H.C., 1968, Some statistical tools in hydrology: 

U.S. Geological Survey Techniques of WaterResources Investigations, Book 4, Chap. A1, 39 p.

-----1972, Low-flow investigations: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 4, Chap. B1, 18 p.

Ross, S.H., and Savage, C.N., 1967, Idaho earth science: Moscow, Idaho Bureau of Mines and Geology, 285 p.

Sando, S.K., 1998, Techniques for estimating peakflow magnitude and frequency relations for South 

Dakota streams: U.S. Geological Survey WaterResources Investigations Report 98-4055, 48 p.

Statware, Inc., 1992, Statit user's guide, release 3.0: 

Corvallis, Oreg., Statware, Inc., 76 p.

U.S. Geological Survey, 1955, Compilation of records 

of surface waters of the United States through September 1950 -- Part 12, Pacific Slope Basins in 

Washington and Upper Columbia River Basin: 

U.S. Geological Survey Water-Supply Paper 1316, 

592 p.

-----1956, Compilation of records of surface waters 

of the United States through September 1950 --

Part 13, Snake River Basin: U.S. Geological Survey Water-Supply Paper 1317, 566 p.

-----1960, Compilation of records of surface waters 

of the United States through September 1950 --

Part 10, The Great Basin: U.S. Geological Survey 

Water-Supply Paper 1314, 485 p.

-----1963, Compilation of records of surface waters 

of the United States, October 1950 through September 1960 -- Part 10, The Great Basin: U.S. Geological Survey Water-Supply Paper 1734, 318 p.

-----1963, Compilation of records of surface waters 

of the United States, October 1950 through September 1960 -- Part 13, Snake River Basin: U.S. 
12 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho

Geological Survey Water-Supply Paper 1737, 

282 p.

-----1964, Compilation of records of surface waters 

of the United States, October 1950 through September 1960 -- Part 12, Pacific Slope Basins in 

Washington and Upper Columbia River Basin: 

U.S. Geological Survey Water-Supply Paper 1736, 

415 p.

-----1962-2000, Water resources data, Idaho, water 

years 1961-1999: U.S. Geological Survey WaterData Reports ID-61 to ID-99 (published annually).
TABLES 3 -10

Table 3. Results of regional regression analysis based on data from 13 gaging stations for region 1 

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; E*, mean 

basin elevation, in thousands of feet above sea level; BR*, basin relief, in thousands of feet; F*, forested area, in percent of drainage area plus 1 percent; Qa, 

mean annual discharge, in cubic feet per second] 

Region 1 

Standard error of 

estimate (log10) 

Standard error of estimate 

Month Equation (percent)

October Q.80 = 9.76E-01 A 0.792 E* -0.435 0.223 67.1 to -40.2 

Q.50 = 4.29E-01 A 0.858 E* 0.225 0.203 59.4 to -37.3 

Q.20 = 5.25E-02 A 0.975 E* 1.87 0.236 72.3 to -42.0 

November Q.80 = 4.16E-01 A 0.879 E* 0.086 0.205 60.1 to -37.6 

Q.50 = 9.55E-02 A 0.966 E* 1.28 0.245 75.9 to -43.1 

Q.20 = 2.85E-02 A 1.00 E* 2.54 0.270 86.1 to -46.3 

December Q.80 = 2.32E-01 A 0.954 E* 0.324 0.230 69.7 to -41.1 

Q.50 = 1.12E-01 A 0.989 E* 1.13 0.243 74.8 to -42.8 

Q.20 = 6.40E-02 A 1.01 E* 1.94 0.257 80.8 to -44.7 

January Q.80 = 2.16E-01 A 0.967 E* 0.367 0.245 75.6 to -43.0 

Q.50 = 1.45E-01 A 1.00 E* 0.856 0.242 74.7 to -42.8 

Q.20 = 1.25E-01 A 1.03 E* 1.28 0.244 75.2 to -42.9 

February Q.80 = 9.27E+02 A 0.838 F* -1.65 0.198 57.9 to -36.7 

Q.50 = 8.09E+02 A 0.854 F* -1.53 0.207 61.0 to -37.9 

Q.20 = 5.79E+02 A 0.852 F* -1.33 0.221 66.3 to -39.9 

March Q.80 = 6.97E+02 A 0.875 F* -1.54 0.208 61.5 to -38.1 

Q.50 = 1.69E+02 A 0.918 F* -1.15 0.223 67.2 to -40.2 

Q.20 = 4.92E+01 A 0.869 F* -0.681 0.223 67.2 to -40.2 

April Q.80 = 8.60E-01 A 0.852 E* 0.769 0.238 73.1 to -42.2 

Q.50 = 6.89E-01 A 0.862 E* 1.34 0.222 66.7 to -40.0 

Q.20 = 4.58E-01 A 0.903 E* 1.95 0.199 58.1 to -36.8 

May Q.80 = 8.51E-02 A 0.778 E* 3.33 0.248 77.0 to -43.5 

Q.50 = 7.18E-02 A 0.836 E* 3.60 0.219 65.6 to -39.6 

Q.20 = 7.59E-02 A 0.860 E* 3.75 0.204 60.0 to -37.5 

June Q.80 = 3.25E-02 A 0.861 E* 3.23 0.278 89.6 to -47.3 

Q.50 = 1.52E-02 A 0.924 E* 4.03 0.275 88.2 to -46.9 

Q.20 = 1.50E-02 A 0.925 E* 4.40 0.267 85.1 to -46.0 

July Q.80 = 1.37E-01 A 0.842 E* 1.32 0.314 106.1 to -51.5 

Q.50 = 7.35E-02 A 0.901 E* 1.99 0.277 89.0 to -47.1 

Q.20 = 2.97E-02 A 0.954 E* 2.92 0.260 82.0 to -45.0 

August Q.80 = 1.20E+00 A 0.844 BR* -0.745 0.310 104.2 to -51.0 

Q.50 = 1.11E+00 A 0.831 BR* -0.386 0.275 88.5 to -46.9 

Q.20 = 1.00E+00 A 0.807 BR* 0.009 0.270 86.4 to -46.3 

September Q.80 = 1.02E+00 A 0.914 BR* -0.934 0.249 77.6 to -43.7 

Q.50 = 9.77E-01 A 0.904 BR* -0.646 0.231 70.2 to -41.2 

Q.20 = 8.81E-01 A 0.827 BR* -0.073 0.237 72.7 to -42.1 

Qa = 1.11E-01 A 0.884 E* 2.30 0.197 57.4 to -36.5 

Table 3 15
Table 4. Results of regional regression analysis based on data from 26 gaging stations for region 2 

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; BR*, basin 

relief, in thousands of feet; P, mean annual precipitation, in inches; F*, forested area, in percent of drainage area plus 1 percent; E*, mean basin elevation, in 

thousands of feet above sea level; Qa, mean annual discharge, in cubic feet per second] 

Region 2 

Standard error of estimate 

Equation (percent) 

Standard error of 

estimate (log10 Month )

October Q.80 = 6.35E-03 A 0.916 BR* 0.656 P 0.892 0.239 73.4 to -42.3 

Q.50 = 1.63E-03 A 0.840 BR* 1.01 P 1.30 0.199 58.1 to -36.8 

Q.20 = 1.86E-04 A 0.822 BR* 1.09 P 1.97 0.192 55.5 to -35.7 

November Q.80 = 2.53E-03 A 0.925 BR* 0.552 P 1.21 0.225 67.7 to -40.4 

Q.50 = 1.22E-03 A 0.916 BR* 0.644 P 1.50 0.205 60.4 to -37.7 

Q.20 = 4.23E-04 A 0.945 BR* 0.416 P 2.01 0.220 65.8 to -39.7 

December Q.80 = 1.52E-07 A 0.990 F* 1.43 P 2.26 0.201 58.7 to -37.0 

Q.50 = 1.52E-07 A 0.995 F* 1.61 P 2.18 0.188 54.3 to -35.2 

Q.20 = 2.34E-08 A 0.983 F* 2.05 P 2.36 0.198 57.6 to -36.5 

January Q.80 = 7.62E-08 A 0.997 F* 1.76 P 2.05 0.197 57.5 to -36.5 

Q.50 = 6.30E-09 A 0.975 F* 2.51 P 2.01 0.187 53.8 to -35.0 

Q.20 = 6.62E-09 A 0.953 F* 2.94 P 1.71 0.208 61.4 to -38.1 

February Q.80 = 3.23E-08 A 0.988 E* -0.292 F* 2.11 P 2.04 0.199 58.3 to -36.8 

Q.50 = 4.38E-07 A 0.967 E* -1.46 F* 2.03 P 2.12 0.183 52.5 to -34.4 

Q.20 = 1.73E-05 A 0.957 E* -2.19 F* 1.56 P 2.17 0.190 55.0 to -35.5 

March Q.80 = 4.03E-07 A 0.996 E* -1.00 F* 2.15 P 1.74 0.185 53.2 to -34.7 

Q.50 = 1.29E-06 A 1.00 E* -1.54 F* 2.07 P 1.87 0.185 53.1 to -34.7 

Q.20 = 2.51E-06 A 0.981 E* -1.97 F* 2.22 P 1.87 0.192 55.5 to -35.7 

April Q.80 = 1.21E-08 A 0.999 E* -0.783 F* 2.45 P 2.46 0.212 62.9 to -38.6 

Q.50 = 1.11E-07 A 0.993 E* -0.696 F* 2.17 P 2.30 0.211 62.4 to -38.4 

Q.20 = 1.26E-06 A 0.978 E* -0.480 F* 1.87 P 2.10 0.199 58.2 to -36.8 

May Q.80 = 1.07E-12 A 1.03 E* 3.18 F* 3.35 P 2.36 0.234 71.3 to -41.6 

Q.50 = 1.27E-10 A 1.02 E* 2.65 F* 2.67 P 2.26 0.223 67.0 to -40.1 

Q.20 = 1.38E-09 A 0.984 E* 2.39 F* 2.51 P 2.08 0.210 62.1 to -38.3 

June Q.80 = 2.87E-09 A 0.800 E* 2.39 BR* 1.60 F* 1.78 P 1.95 0.198 57.9 to -36.7 

Q.50 = 5.11E-10 A 0.790 E* 2.64 BR* 1.67 F* 2.31 P 1.82 0.205 60.4 to -37.6 

Q.20 = 3.50E-10 A 0.791 E* 2.34 BR* 1.74 F* 2.56 P 1.86 0.206 60.8 to -37.8 

July Q.80 = 1.26E-08 A 0.793 E* 1.47 BR* 1.44 F* 1.88 P 1.62 0.202 59.2 to -37.2 

Q.50 = 6.46E-08 A 0.784 E* 1.79 BR* 1.45 F* 1.59 P 1.52 0.194 56.4 to -36.1 

Q.20 = 1.61E-07 A 0.755 E* 1.82 BR* 1.73 F* 1.40 P 1.54 0.193 55.8 to -35.8 

August Q.80 = 1.03E-10 A 0.963 E* 2.58 F* 2.92 P 1.43 0.232 70.7 to -41.4 

Q.50 = 3.40E-09 A 0.960 E* 2.70 F* 2.32 P 1.25 0.230 69.9 to -41.2 

Q.20 = 1.07E-08 A 0.947 E* 2.78 F* 2.10 P 1.26 0.221 66.1 to -39.8 

September Q.80 = 3.75E-11 A 0.962 E* 2.06 F* 3.28 P 1.43 0.236 72.0 to -41.9 

Q.50 = 2.49E-09 A 0.954 E* 2.26 F* 2.51 P 1.23 0.221 66.3 to -39.9 

Q.20 = 9.62E-08 A 0.937 E* 2.10 F* 1.76 P 1.30 0.205 60.4 to -37.6 

Qa = 5.14E-06 A 0.986 F* 0.942 P 2.33 0.194 56.5 to -36.1 

16 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Table 5. Results of regional regression analysis based on data from 9 gaging stations for region 3 

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; E*, mean 

basin elevation, in thousands of feet above sea level; P, mean annual precipitation, in inches; Qa, mean annual discharge, in cubic feet per second] 

Region 3 

Standard error of Standard error of estimate 

Month Equation estimate (log10) (percent) 

October Q.80 

Q.50 

Q.20 

November Q.80 

Q.50 

Q.20 

December Q.80 

Q.50 

Q.20 

January Q.80 

Q.50 

Q.20 

February Q.80 

Q.50 

Q.20 

March Q.80 

Q.50 

Q.20 

April Q.80 

Q.50 

Q.20 

May Q.80 

Q.50 

Q.20 

June Q.80 

Q.50 

Q.20 

July Q.80 

Q.50 

Q.20 

August Q.80 

Q.50 

Q.20 

September Q.80 

Q.50 

Q.20 

Qa 

= 1.56E-04 A 0.659 E* 6.54 0.156 43.4 to -30.2 

= 2.61E-04 A 0.850 E* 5.53 0.108 28.3 to -22.1 

= 2.49E-04 A 1.00 E* 5.17 0.113 29.7 to -22.9 

= 1.97E-04 A 0.872 E* 5.69 0.121 32.1 to -24.3 

= 1.83E-04 A 1.06 E* 5.20 0.125 33.2 to -24.9 

= 5.61E-04 A 1.09 E* 4.61 0.271 86.8 to -46.5 

= 2.61E-04 A 1.02 E* 5.00 0.095 24.5 to -19.7 

= 5.93E-04 A 1.12 E* 3.96 0.178 50.7 to -33.7 

= 3.52E-02 A 1.21 E* 1.19 0.203 59.7 to -37.4 

= 5.07E-04 A 1.09 E* 4.29 0.090 22.9 to -18.7 

= 5.93E-02 A 1.05 E* 1.12 0.182 52.2 to -34.3 

= 1.74E+00 A 1.10 E* -1.07 0.192 55.4 to -35.7 

= 2.09E-04 A 1.08 P 2.03 0.115 30.3 to -23.2 

= 1.70E-04 A 1.03 P 2.48 0.081 20.5 to -17.0 

= 8.51E-05 A 1.02 P 3.02 0.166 46.5 to -31.8 

= 6.12E-06 A 1.20 P 3.11 0.113 29.6 to -22.9 

= 4.10E-05 A 1.10 P 2.94 0.111 29.2 to -22.6 

= 1.15E-04 A 1.10 P 2.85 0.172 48.5 to -32.7 

= 5.46E-07 A 1.41 P 3.49 0.253 78.9 to -44.1 

= 4.39E-07 A 1.40 P 3.80 0.193 55.9 to -35.8 

= 4.97E-06 A 1.33 P 3.36 0.183 52.5 to -34.4 

= 4.25E-05 A 1.27 E* 6.15 0.183 52.5 to -34.4 

= 5.51E-05 A 1.39 E* 5.99 0.214 63.5 to -38.8 

= 2.60E-04 A 1.40 E* 5.24 0.249 77.6 to -43.7 

= 5.52E-05 A 1.02 E* 6.47 0.154 42.4 to -29.8 

= 4.18E-05 A 1.15 E* 6.60 0.127 33.8 to -25.3 

= 3.96E-05 A 1.24 E* 6.79 0.183 52.4 to -34.4 

= 1.17E-04 A 0.647 E* 6.84 0.208 61.3 to -38.0 

= 1.03E-04 A 0.882 E* 6.29 0.127 34.0 to -25.4 

= 9.48E-05 A 1.04 E* 5.99 0.092 23.7 to -19.1 

= 1.95E-04 A 0.337 E* 7.32 0.370 134.4 to -57.3 

= 2.37E-04 A 0.640 E* 6.24 0.185 53.0 to -34.7 

= 2.31E-04 A 0.843 E* 5.67 0.120 31.8 to -24.1 

= 1.36E-04 A 0.413 E* 7.41 0.258 81.3 to -44.8 

= 2.74E-04 A 0.713 E* 5.88 0.140 38.1 to -27.6 

= 2.94E-04 A 0.866 E* 5.40 0.093 23.9 to -19.3 

= 7.73E-05 A 1.10 P 2.56 0.072 18.1 to -15.3 

Table 5 17
Table 6. Results of regional regression analysis based on data from 43 gaging stations for region 4 

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; BS, basin 

slope, in percent; P, mean annual precipitation, in inches; E*, mean basin elevation, in thousands of feet above sea level; F*, forested area, in percent of drainage

area plus 1 percent; Qa, mean annual discharge, in cubic feet per second] 

Region 4 

Standard error of 

estimate (log10) 

Standard error of estimate 

Month Equation (percent)

October Q.80 = 2.17E-05 A 1.03 BS 1.30 P 1.23 0.267 84.9 to -45.9 

Q.50 = 2.53E-05 A 1.06 BS 1.16 P 1.37 0.246 76.2 to -43.2 

Q.20 = 2.42E-05 A 1.07 BS 1.05 P 1.57 0.218 65.1 to -39.4 

November Q.80 = 5.04E-05 A 1.04 BS 1.14 P 1.20 0.233 71.0 to -41.5 

Q.50 = 4.55E-05 A 1.06 BS 1.03 P 1.39 0.211 62.5 to -38.5 

Q.20 = 4.70E-05 A 1.08 BS 0.776 P 1.75 0.198 57.8 to -36.6 

December Q.80 = 7.85E-05 A 1.04 BS 1.04 P 1.19 0.235 71.8 to -41.8 

Q.50 = 1.22E-04 A 1.05 BS 0.920 P 1.28 0.207 61.2 to -38.0 

Q.20 = 5.47E-04 A 1.06 BS 0.380 P 1.53 0.234 71.4 to -41.6 

January Q.80 = 2.28E-04 A 1.04 BS 1.07 E* -0.696 P 1.18 0.216 64.2 to -39.1 

Q.50 = 6.55E-04 A 1.06 BS 0.980 E* -1.15 P 1.28 0.208 61.4 to -38.1 

Q.20 = 2.21E-02 A 1.04 BS 0.973 E* -2.27 P 1.01 0.175 49.6 to -33.2 

February Q.80 = 1.44E-03 A 1.05 BS 1.16 E* -1.34 P 0.925 0.198 57.9 to -36.7 

Q.50 = 1.55E-02 A 1.05 BS 0.979 E* -1.89 P 0.825 0.183 52.4 to -34.4 

Q.20 = 4.04E-01 A 1.04 BS 0.798 E* -2.67 P 0.621 0.164 45.7 to -31.4 

March Q.80 = 1.26E-02 A 1.11 BS 0.581 E* -1.66 P 1.07 0.222 66.6 to -40.0 

Q.50 = 2.71E-01 A 1.08 BS 0.293 E* -2.03 P 0.855 0.186 53.6 to -34.9 

Q.20 = 3.38E+00 A 1.05 BS 0.023 E* -2.28 P 0.726 0.179 51.1 to -33.8 

April Q.80 = 7.10E-03 A 1.01 E* -1.56 F* 1.14 P 0.799 0.228 69.2 to -40.9 

Q.50 = 6.47E-02 A 0.992 E* -1.62 F* 0.912 P 0.646 0.177 50.2 to -33.4 

Q.20 = 3.37E-01 A 0.958 E* -1.38 F* 0.670 P 0.560 0.149 40.9 to -29.0 

May Q.80 = 2.93E-05 A 1.11 F* 0.885 P 1.90 0.241 74.1 to -42.5 

Q.50 = 4.35E-05 A 1.07 F* 1.09 P 1.73 0.232 70.4 to -41.3 

Q.20 = 5.35E-04 A 1.04 F* 0.732 P 1.64 0.149 40.9 to -29.0 

June Q.80 = 3.33E-07 A 1.19 E* 2.53 F* 0.121 P 2.63 0.233 70.9 to -41.5 

Q.50 = 4.74E-07 A 1.21 E* 2.35 F* 0.368 P 2.47 0.266 84.5 to -45.8 

Q.20 = 1.77E-06 A 1.19 E* 1.93 F* 0.411 P 2.41 0.246 76.2 to -43.3 

July Q.80 = 8.00E-07 A 1.09 E* 2.28 P 2.44 0.283 91.9 to -47.9 

Q.50 = 3.49E-07 A 1.13 E* 2.70 P 2.58 0.222 66.8 to -40.1 

Q.20 = 2.12E-07 A 1.17 E* 2.75 P 2.80 0.222 66.6 to -40.0 

August Q.80 = 2.07E-06 A 1.06 BS 1.26 P 1.86 0.374 136.3 to -57.7 

Q.50 = 2.92E-06 A 1.09 BS 1.14 P 1.95 0.311 104.7 to -51.1 

Q.20 = 3.82E-06 A 1.11 BS 0.934 P 2.15 0.256 80.3 to -44.5 

September Q.80 = 4.93E-06 A 1.04 BS 1.30 P 1.58 0.366 132.0 to -56.9 

Q.50 = 7.89E-06 A 1.07 BS 1.13 P 1.66 0.295 97.2 to -49.3 

Q.20 = 1.08E-05 A 1.08 BS 1.03 P 1.75 0.266 84.5 to -45.8 

Qa = 1.28E-03 A 1.05 F* 0.180 P 1.64 0.139 37.8 to -27.4 

18 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Table 7. Results of regional regression analysis based on data from 30 gaging stations for region 5 

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; BS, basin slope 

in percent; S30*, slopes greater than 30 percent, in percent of drainage area plus 1 percent; F*, forested area, in percent of drainage area plus 1 percent; E*, mean 

basin elevation, in thousands of feet above sea level; Qa, mean annual discharge, in cubic feet per second] 

Region 5 

Standard error of 

estimate (log10) 

Standard error of estimate 

Month Equation (percent)

October Q.80 = 4.01E-03 A 0.857 BS 5.83 S30* -4.71 F* 0.847 0.244 75.4 to -43.0 

Q.50 = 7.87E-03 A 0.873 BS 5.89 S30* -4.56 F* 0.528 0.154 42.5 to -29.8 

Q.20 = 8.91E-03 A 0.863 BS 6.96 S30* -5.33 F* 0.413 0.132 35.4 to -26.2 

November Q.80 = 8.83E-03 A 0.839 BS 6.07 S30* -4.98 F* 0.735 0.262 82.7 to -45.3 

Q.50 = 1.07E-02 A 0.867 BS 6.56 S30* -5.08 F* 0.400 0.144 39.3 to -28.2 

Q.20 = 1.10E-02 A 0.850 BS 7.53 S30* -5.77 F* 0.325 0.128 34.4 to -25.6 

December Q.80 = 2.05E-01 A 0.773 BS 6.87 S30* -5.64 0.306 102.1 to -50.5 

Q.50 = 5.22E-02 A 0.834 BS 6.97 S30* -5.39 0.162 45.3 to -31.2 

Q.20 = 2.96E-02 A 0.832 BS 7.81 S30* -5.92 0.156 43.1 to -30.1 

January Q.80 = 2.57E-01 A 0.776 BS 6.84 S30* -5.68 0.332 114.6 to -53.4 

Q.50 = 6.03E-02 A 0.839 BS 6.68 S30* -5.20 0.177 50.2 to -33.4 

Q.20 = 4.84E-02 A 0.848 BS 7.04 S30* -5.41 0.172 48.5 to -32.7 

February Q.80 = 2.65E-01 A 0.777 BS 6.71 S30* -5.57 0.345 121.5 to -54.8 

Q.50 = 6.46E-02 A 0.851 BS 6.44 S30* -5.02 0.178 50.8 to -33.7 

Q.20 = 5.32E-02 A 0.869 BS 6.35 S30* -4.86 0.181 51.5 to -34.0 

March Q.80 = 5.07E+00 A 0.780 E* -2.08 BS 7.79 S30* -6.22 0.294 96.6 to -49.1 

Q.50 = 8.06E-01 A 0.871 E* -1.65 BS 6.59 S30* -4.97 0.178 50.7 to -33.6 

Q.20 = 2.86E+00 A 0.866 E* -2.57 BS 6.81 S30* -4.95 0.189 54.4 to -35.2 

April Q.80 = 1.07E+02 A 0.919 E* -2.45 S30* -0.00410 0.221 66.3 to -39.9 

Q.50 = 3.66E+02 A 0.900 E* -3.07 S30* 0.160 0.235 71.8 to -41.8 

Q.20 = 2.67E+02 A 0.890 E* -2.39 S30* 0.103 0.231 70.1 to -41.2 

May Q.80 = 2.29E-01 A 0.790 BS 7.42 S30* -5.69 0.223 67.1 to -40.2 

Q.50 = 2.77E-01 A 0.798 BS 7.36 S30* -5.56 0.189 54.7 to -35.3 

Q.20 = 5.37E-01 A 0.802 BS 7.06 S30* -5.35 0.163 45.6 to -31.3 

June Q.80 = 2.22E-04 A 0.810 BS 10.7 S30* -7.89 F* 0.993 0.170 48.0 to -32.4 

Q.50 = 5.12E-04 A 0.832 BS 9.84 S30* -7.28 F* 1.04 0.134 36.1 to -26.5 

Q.20 = 1.27E-03 A 0.824 BS 9.37 S30* -6.88 F* 0.942 0.132 35.5 to -26.2 

July Q.80 = 9.71E-05 A 0.837 BS 9.44 S30* -6.88 F* 0.965 0.189 54.6 to -35.3 

Q.50 = 1.91E-04 A 0.824 BS 10.7 S30* -7.85 F* 0.773 0.160 44.7 to -30.9 

Q.20 = 2.14E-04 A 0.831 BS 11.5 S30* -8.36 F* 0.705 0.145 39.5 to -28.3 

August Q.80 = 1.04E-04 A 0.864 BS 7.72 S30* -5.65 F* 1.04 0.232 70.7 to -41.4 

Q.50 = 2.52E-04 A 0.865 BS 8.06 S30* -5.89 F* 0.848 0.200 58.5 to -36.9 

Q.20 = 4.51E-04 A 0.855 BS 8.50 S30* -6.21 F* 0.736 0.175 49.8 to -33.2 

September Q.80 = 4.59E-04 A 0.872 BS 6.50 S30* -4.98 F* 1.03 0.243 75.0 to -42.9 

Q.50 = 1.83E-03 A 0.876 BS 6.33 S30* -4.77 F* 0.710 0.162 45.2 to -31.2 

Q.20 = 3.51E-03 A 0.863 BS 6.63 S30* -4.98 F* 0.569 0.149 41.0 to -29.1 

Qa = 1.07E-02 A 0.831 BS 7.25 S30* -5.42 F* 0.448 0.139 37.7 to -27.4 

Table 7 19
Table 8. Results of regional regression analysis based on data from 23 gaging stations for region 6

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; BS, basin

slope, in percent; F*, forested area, in percent of drainage area plus 1 percent; E*, mean basin elevation, in thousands of feet above sea level; BR*, basin relief,

in thousands of feet; Qa, mean annual discharge, in cubic feet per second]

Month

Standard error of 

estimate (log10)

October Q.80 = 2.77E-05 A 1.12 BS 2.23 0.362 129.9 to -56.5

Q.50 = 3.42E-05 A 1.12 BS 2.32 0.392 146.5 to -59.4

Q.20 = 2.15E-03 A 1.05 BS 1.34 0.230 69.6 to -41.0

November Q.80 = 3.82E-05 A 1.15 BS 2.17 0.374 136.5 to -57.7

Q.50 = 1.34E-04 A 1.12 BS 1.91 0.367 132.8 to -57.0

Q.20 = 3.76E-03 A 1.05 BS 1.15 0.201 58.9 to -37.0

December Q.80 = 3.77E-05 A 1.13 BS 2.15 0.352 125.0 to -55.6

Q.50 = 9.66E-05 A 1.12 BS 1.96 0.354 125.9 to -55.7

Q.20 = 2.06E-03 A 1.07 BS 1.25 0.194 56.4 to -36.1

January Q.80 = 3.18E-05 A 1.14 BS 2.17 0.337 117.1 to -53.9

Q.50 = 8.77E-05 A 1.12 BS 1.96 0.341 119.1 to -54.4

Q.20 = 1.36E-03 A 1.07 BS 1.34 0.198 57.8 to -36.6

February Q.80 = 2.88E-05 A 1.16 BS 2.17 0.335 116.3 to -53.8

Q.50 = 8.32E-05 A 1.14 BS 1.96 0.345 121.4 to -54.8

Q.20 = 2.04E-03 A 1.06 BS 1.24 0.194 56.2 to -36.0

March Q.80 = 3.55E-05 A 1.16 BS 2.12 0.336 116.7 to -53.9

Q.50 = 5.55E-04 A 1.10 BS 1.51 0.227 68.7 to -40.7

Q.20 = 5.45E-03 A 1.04 BS 1.03 0.169 47.5 to -32.2

April Q.80 = 5.40E-03 A 1.05 BS 0.98 F* -0.0111 0.186 53.6 to -34.9

Q.50 = 6.14E-02 A 0.993 BS 0.360 F* 0.110 0.173 48.9 to -32.9

Q.20 = 2.36E-01 A 0.941 BS -0.0246 F* 0.343 0.209 61.7 to -38.1

May Q.80 = 1.47E-07 A 1.09 E* 5.04 F* 1.12 0.262 82.9 to -45.3

Q.50 = 5.46E-06 A 1.00 E* 4.14 F* 0.959 0.217 64.8 to -39.3

Q.20 = 3.99E-05 A 0.943 E* 3.77 F* 0.874 0.225 67.8 to -40.4

June Q.80 = 8.59E-14 A 0.977 E* 10.49 BR* 2.07 F* 1.31 0.363 130.7 to -56.6

Q.50 = 2.05E-09 A 0.929 E* 7.39 BR* 1.27 F* 0.923 0.192 55.6 to -35.7

Q.20 = 3.81E-07 A 0.879 E* 5.77 BR* 0.971 F* 0.764 0.170 47.8 to -32.3

July Q.80 = 5.20E-11 A 1.12 E* 7.05 BS 2.09 0.346 121.8 to -54.9

Q.50 = 4.18E-10 A 1.13 E* 7.25 BS 1.54 0.263 83.3 to -45.4

Q.20 = 1.92E-08 A 1.08 E* 6.32 BS 1.22 0.195 56.6 to -36.1

August Q.80 = 3.56E-10 A 1.09 E* 6.31 BS 1.87 0.323 110.2 to -52.4

Q.50 = 3.16E-10 A 1.11 E* 6.53 BS 1.86 0.339 118.1 to -54.1

Q.20 = 2.83E-08 A 1.05 E* 6.23 BS 0.971 0.204 59.9 to -37.5

September Q.80 = 2.78E-09 A 1.12 E* 5.20 BS 1.86 0.309 103.7 to -50.9

Q.50 = 1.80E-09 A 1.14 E* 5.56 BS 1.84 0.321 109.6 to -52.3

Q.20 = 1.81E-07 A 1.08 E* 5.13 BS 0.973 0.190 54.7 to -35.4

Qa = 7.18E-03 A 0.975 BS 1.23 0.230 69.7 to -41.1

Equation

Standard error of estimate 

(percent)

Region 6

20 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Table 9. Results of regional regression analysis based on data from 25 gaging stations for region 7

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; MCS, main channel slope, in feet per mile; F*,

forested area, in percent of drainage area plus 1 percent; E*, mean basin elevation, in thousands of feet above sea level; S30*, slopes greater than 30 percent, in

percent of drainage area plus 1 percent; A, drainage area, in square miles; BS, basin slope, in percent; P, mean annual precipitation, in inches; Qa, mean annual 

discharge, in cubic feet per second]

Month

Standard error of 

estimate (log10)

October Q.80 = 2.27E+02 MCS -1.09 F* 0.432 0.417 161.2 to -61.7

Q.50 = 5.77E+02 MCS -1.27 F* 0.523 0.376 137.8 to -58.0

Q.20 = 1.56E+03 MCS -1.43 F* 0.568 0.309 103.6 to -50.9

November Q.80 = 5.28E+02 MCS -1.26 F* 0.503 0.334 115.9 to -53.7

Q.50 = 9.89E+02 MCS -1.36 F* 0.568 0.299 99.2 to -49.8

Q.20 = 1.71E+03 MCS -1.42 F* 0.594 0.278 89.8 to -47.3

December Q.80 = 5.97E+02 MCS -1.26 F* 0.507 0.283 91.9 to -47.9

Q.50 = 1.02E+03 MCS -1.35 F* 0.565 0.282 91.2 to -47.7

Q.20 = 1.14E+03 MCS -1.29 F* 0.606 0.316 107.0 to -51.7

January Q.80 = 1.16E+03 E* -0.526 S30* 0.209 MCS -1.33 F* 0.485 0.281 90.9 to -47.6

Q.50 = 5.82E+03 E* -1.55 S30* 0.468 MCS -1.41 F* 0.548 0.275 88.4 to -46.9

Q.20 = 1.27E+05 E* -3.85 S30* 1.02 MCS -1.49 F* 0.705 0.277 89.2 to -47.2

February Q.80 = 3.49E+03 E* -1.13 S30* 0.488 MCS -1.47 F* 0.470 0.274 88.1 to -46.8

Q.50 = 5.18E+04 E* -3.06 S30* 0.939 MCS -1.53 F* 0.537 0.300 99.7 to -49.9

Q.20 = 3.05E+05 E* -4.06 S30* 1.21 MCS -1.56 F* 0.515 0.353 125.4 to -55.6

March Q.80 = 4.10E-01 A 0.922 E* -1.75 S30* 0.354 F* 0.537 0.364 131.0 to -56.7

Q.50 = 1.58E+00 A 1.00 E* -2.97 S30* 0.684 F* 0.546 0.379 139.1 to -58.2

Q.20 = 6.34E+00 A 1.04 E* -3.59 S30* 0.820 F* 0.470 0.366 132.2 to -56.9

April Q.80 = 1.17E+04 BS -3.34 S30* 2.80 MCS -1.52 F* 0.795 0.323 110.5 to -52.5

Q.50 = 9.86E+03 BS -2.12 S30* 2.01 MCS -1.55 F* 0.746 0.380 139.6 to -58.3

Q.20 = 7.66E+03 BS -0.607 S30* 1.02 MCS -1.57 F* 0.570 0.417 161.5 to -61.8

May Q.80 = 1.28E+01 MCS -1.48 F* 0.817 P 1.90 0.401 151.5 to -60.2

Q.50 = 1.38E+01 MCS -1.49 F* 0.862 P 2.13 0.448 180.3 to -64.3

Q.20 = 1.91E+01 MCS -1.43 F* 0.699 P 2.26 0.422 163.9 to -62.1

June Q.80 = 5.47E+01 MCS -1.46 F* 0.775 P 1.21 0.387 143.7 to -59.0

Q.50 = 3.59E+01 MCS -1.53 F* 0.844 P 1.65 0.424 165.6 to -62.4

Q.20 = 4.31E+01 MCS -1.55 F* 0.739 P 1.90 0.427 167.4 to -62.6

July Q.80 = 2.66E+02 MCS -1.21 F* 0.587 P 0.0617 0.456 185.6 to -65.0

Q.50 = 2.43E+02 MCS -1.36 F* 0.698 P 0.464 0.407 155.3 to -60.8

Q.20 = 2.85E+02 MCS -1.55 F* 0.734 P 0.876 0.380 140.0 to -58.3

August Q.80 = 1.34E+02 MCS -1.03 F* 0.465 0.498 214.8 to -68.2

Q.50 = 4.80E+02 MCS -1.28 F* 0.571 0.471 195.7 to -66.2

Q.20 = 9.86E+02 MCS -1.39 F* 0.648 0.420 163.3 to -62.0

September Q.80 = 1.10E+02 MCS -0.992 F* 0.469 0.483 204.1 to -67.1

Q.50 = 3.98E+02 MCS -1.23 F* 0.503 0.466 192.2 to -65.8

Q.20 = 9.48E+02 MCS -1.36 F* 0.547 0.435 172.3 to -63.3

Qa = 8.37E-01 A 0.963 BS -3.44 S30* 2.52 F* 0.646 0.316 107.2 to -51.7

Equation

Standard error of estimate 

(percent)

Region 7

Table 9 21
Table 10. Results of regional regression analysis based on data from 31 gaging stations for region 8

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; A, drainage area, in square miles; F*,

forested area, in percent of drainage area plus 1 percent; P, mean annual precipitation, in inches; E*, mean basin elevation, in thousands of feet above

sea level; BS, basin slope, in percent; S30*, slopes greater than 30 percent, in percent of drainage area plus 1 percent; Qa, mean annual discharge, in

cubic feet per second]

Month

Standard error of 

estimate (log10)

October Q.80 = 9.18E-06 A 1.07 F* -0.950 P 4.03 0.367 133.0 to -57.1

Q.50 = 1.04E-05 A 1.08 F* -0.999 P 4.09 0.350 123.7 to -55.3

Q.20 = 1.53E-04 A 1.05 F* -0.992 P 3.44 0.275 88.3 to -46.9

November Q.80 = 5.75E-06 A 1.09 F* -1.07 P 4.24 0.358 127.8 to -56.1

Q.50 = 2.11E-05 A 1.07 F* -0.999 P 3.89 0.303 100.9 to -50.2

Q.20 = 1.27E-04 A 1.04 F* -1.05 P 3.54 0.272 87.1 to -46.6

December Q.80 = 5.14E-03 A 1.05 E* -3.75 F* -0.876 P 4.31 0.340 118.6 to -54.3

Q.50 = 2.02E-02 A 1.02 E* -3.52 F* -0.824 P 3.83 0.288 93.9 to -48.4

Q.20 = 6.27E-02 A 1.00 E* -3.43 F* -0.819 P 3.54 0.267 84.8 to -45.9

January Q.80 = 1.29E-02 A 1.05 E* -3.85 F* -0.908 P 4.13 0.338 117.5 to -54.0

Q.50 = 5.20E-02 A 1.01 E* -3.81 F* -0.853 P 3.76 0.300 99.6 to -49.9

Q.20 = 1.01E-01 A 0.987 E* -3.60 F* -0.809 P 3.49 0.272 87.0 to -46.5

February Q.80 = 2.47E-02 A 1.05 E* -3.86 F* -0.947 P 3.99 0.328 112.6 to -53.0

Q.50 = 5.90E-02 A 1.01 E* -3.78 F* -0.864 P 3.71 0.299 98.9 to -49.7

Q.20 = 1.49E-01 A 0.979 E* -3.74 F* -0.784 P 3.44 0.273 87.3 to -46.6

March Q.80 = 4.79E-02 A 1.02 E* -3.76 F* -0.855 P 3.71 0.293 96.5 to -49.1

Q.50 = 1.77E-01 A 0.975 E* -3.67 F* -0.788 P 3.33 0.271 86.7 to -46.4

Q.20 = 1.07E+00 A 0.934 E* -3.60 F* -0.735 P 2.85 0.259 81.5 to -44.9

April Q.80 = 2.75E+02 A 0.871 E* -5.49 BS 0.146 P 1.50 0.236 72.3 to -42.0

Q.50 = 8.65E+02 A 0.835 E* -5.11 BS 0.210 P 1.07 0.194 56.1 to -36.0

Q.20 = 1.18E+03 A 0.844 E* -4.28 BS 0.180 P 0.678 0.155 43.0 to -30.0

May Q.80 = 1.71E+01 A 0.923 E* -4.29 BS 0.456 P 1.53 0.248 77.0 to -43.5

Q.50 = 1.06E+01 A 0.908 E* -3.26 BS 0.412 P 1.28 0.248 76.8 to -43.5

Q.20 = 6.88E+00 A 0.891 E* -2.28 BS 0.394 P 1.02 0.244 75.5 to -43.0

June Q.80 = 2.22E-06 A 1.18 BS 0.956 F* -0.778 P 3.64 0.287 93.6 to -48.4

Q.50 = 4.37E-05 A 1.10 BS 0.838 F* -0.899 P 3.31 0.265 83.9 to -45.6

Q.20 = 2.96E-04 A 1.07 BS 0.798 F* -0.787 P 2.84 0.267 84.9 to -45.9

July Q.80 = 2.05E-06 A 1.16 S30* 0.646 F* -0.861 P 3.81 0.354 125.9 to -55.7

Q.50 = 7.85E-06 A 1.17 S30* 0.586 F* -0.716 P 3.44 0.299 98.8 to -49.7

Q.20 = 2.12E-05 A 1.16 S30* 0.525 F* -0.591 P 3.22 0.265 84.0 to -45.6

August Q.80 = 1.52E-06 A 1.12 S30* 0.471 F* -0.989 P 4.13 0.374 136.4 to -57.7

Q.50 = 1.17E-06 A 1.16 S30* 0.514 F* -1.05 P 4.26 0.332 114.9 to -53.5

Q.20 = 1.04E-05 A 1.12 S30* 0.400 F* -0.897 P 3.73 0.278 89.7 to -47.3

September Q.80 = 1.14E-05 A 1.04 F* -0.834 P 3.89 0.385 142.8 to -58.8

Q.50 = 1.31E-05 A 1.05 F* -0.838 P 3.90 0.370 134.4 to -57.3

Q.20 = 3.64E-05 A 1.05 F* -0.857 P 3.72 0.321 109.5 to -52.3

Qa = 2.72E-02 A 1.03 E* -2.36 BS 0.522 F* -0.659 P 2.70 0.209 61.8 to -38.2

Standard error of estimate 

(percent)

Region 8

Equation

22 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
APPENDICES

Appendix A. Selected streamflow-gaging stations and periods of record used in regression analysis

Map 

number 

(fig. 1)

Gaging 

station 

number Gaging station name

Period of record 

(in water years)

1 12305500 Boulder Creek near Leonia, ID 1928-72,1973-77

2 12311000 Deep Creek at Moravia, ID 1928-72

3 12316800 Mission Creek near Copeland, ID 1958-82

4 12320500 Long Canyon Creek near Porthill, ID 1931-59

5 12321000 Smith Creek near Porthill, ID 1928-60

6 12392155 Lightning Creek at Clark Fork, ID 1989-99

7 12392300 Pack River near Colburn, ID 1958-83

8 12393500 Priest River at Outlet of Priest Lake near Coolin, ID 1912-48

9 12396000 Calispell Creek near Dalkena, WA 1950-73

10 12408500 Mill Creek near Colville, WA 1939-72,1977-86

11 12409000 Colville River at Kettle Falls, WA 1923-99

12 12427000 Little Spokane River at Elk, WA 1948-71

13 12431000 Little Spokane River at Dartford, WA 1929-32,1946-99

14 12302500 Granite Creek near Libby, MT 1933-34,1936-44,1960-69

15 12303100 Flower Creek near Libby, MT 1960-92

16 12303500 Lake Creek at Troy, MT 1945-57,1983-95

17 12347500 Blodgett Creek near Corvallis, MT 1947-69

18 12350500 Kootenai Creek near Stevensville, MT 1949-53,1957-63

19 12354000 St. Regis River near St. Regis, MT 1910-17,1958-75

20 12389500 Thompson River near Thompson Falls, MT 1911-16,1956-99

21 12390700 Prospect Creek at Thompson Falls, MT 1956-99

22 12411000 North Fork Coeur d'Alene River above Shoshone Creek near Prichard, ID 1950-99

23 12413000 North Fork Coeur d'Alene River at Enaville, ID 1911-13,1939-99

24 12413140 Placer Creek at Wallace, ID 1967-97,1999

25 12413150 South Fork Coeur d'Alene River at Silverton, ID 1967-88,1998-99

26 12413210 South Fork Coeur d'Alene at Elizabeth Park near Kellogg, ID 1987-99

27 12413470 South Fork Coeur d'Alene River near Pinehurst, ID 1987-99

28 12413500 Coeur d'Alene River at Cataldo, ID 1911-12,1920-72,1987-99

29 12414500 St. Joe River at Calder, ID 1911-12,1920-99

30 12414900 St. Maries River near Santa, ID 1966-99

31 12415000 St. Maries River at Lotus, ID 1912-13,1920-66

32 12416000 Hayden Creek below North Fork near Hayden Lake, ID 1948-84,1959,1966-97

33 13336500 Selway River near Lowell, ID 1911-12,1930-99

34 13336900 Fish Creek near Lowell, ID 1958-67

35 13337000 Lochsa River near Lowell, ID 1911-12,1930-99

36 13340500 NF Clearwater River at Bungalow Ranger Station, ID 1945-69

37 13340600 NF Clearwater River near Canyon Ranger Station, ID 1967-99

38 13341300 Bloom Creek near Bovill, ID 1959-72

39 13341400 East Fork Potlatch River near Bovill, ID 1959-72

40 12424000 Hangman Creek at Spokane, WA 1948-99

41 13334700 Asotin Creek below Kearney Gulch near Asotin, WA 1960-82,1992

42 13345000 Palouse River near Potlatch, ID 1915-19,1966-99

43 13346100 Palouse River at Colfax, WA 1964-73,1976-79

44 13346800 Paradise Creek at University of Idaho at Moscow, ID 1979-99

45 13348000 South Fork Palouse River at Pullman, WA 1934-42,1960-81

46 13348500 Missouri Flat Creek at Pullman, WA 1934-40,1960-79

47 13341500 Potlatch River at Kendrick, ID 1946-60

48 13342450 Lapwai Creek near Lapwai, ID 1975-99

49 13196500 Bannock Creek near Idaho City, ID 1939-42,1951-72

50 13200000 Mores Creek above Robie Creek near Arrowrock Dam, ID 1951-99

51 13200500 Robie Creek near Arrowrock Dam, ID 1951-72

52 13201000 Mores Creek near Arrowrock, ID 1916-54

53 13207000 Spring Valley Creek near Eagle, ID 1955-59,1961-72

54 13207500 Dry Creek near Eagle, ID 1954-68

55 13216500 North Fork Malheur River above Beulah Reservoir near Beulah, OR 1914,1936-94

56 13250600 Big Willow Creek near Emmett, ID 1962-83

57 13251300 West Branch Weiser River near Tamarack, ID 1959-78

58 13251500 Weiser River at Tamarack, ID 1937-72,1974-76

59 13253500 Weiser River at Starkey, ID 1939-49

60 13256000 Weiser River near Council, ID 1937-53

61 13257000 Middle Fork Weiser River near Mesa, ID 1911-13,1919-22,1937-49,1981-83,1985-88

62 13258500 Weiser River near Cambridge, ID 1939-99

63 13260000 Pine Creek near Cambridge, ID 1938-92

64 13261000 Little Weiser River near Indian Valley, ID 1920-21,1923-27,1938-71

65 13266000 Weiser River near Weiser, ID 1890-91,1894-1904,1910-14,1953-99

66 13267000 Mann Creek near Weiser, ID 1911-13,1920-21,1937-62

67 13269300 North Fork Burnt River near Whitney, OR 1965-80

68 13270800 South Fork Burnt River above Barney Creek near Unity, OR 1963-81

69 13275500 Powder River near Baker, OR 1904-14,1929-68

70 13288200 Eagle Creek above Skull Creek near New Bridge, OR 1958-95

71 13289960 Wildhorse River at Brownlee Dam, ID 1979-96

72 13290190 Pine Creek near Pine, OR 1967-96

Region 2

Region 1

Region 3

Region 4

Appendix A 25
Appendix A. Selected streamflow-gaging stations and periods of record used in regression analyses--Continued

Map 

number 

(fig. 1)

Gaging 

station 

number Gaging station name

Period of record 

(in water years)

73 13315500 Mud Creek near Tamarack, ID 1937-38,1946-59

74 13316500 Little Salmon River at Riggins, ID 1951-55,1956-99

75 13316800 NF Skookumchuck Creek near White Bird, ID 1961-72

76 13317000 Salmon River at White Bird, ID 1910-17,1920-99

77 13319000 Grande Ronde River at La Grande, OR 1904-15,1918-23,1926-89

78 13320000 Catherine Creek near Union, OR 1926-96

79 13323600 Indian Creek near Imbler, OR 1938-50

80 13329500 Hurricane Creek near Joseph, OR 1915,1924-78

81 13330000 Lostine River near Lostine, OR 1912-15,1925-91,1995-99

82 13330500 Bear Creek near Wallowa, OR 1915,1924-85,1995-99

83 13331500 Minam River at Minam, OR 1912-14,1965-99

84 13337500 South Fork Clearwater River near Elk City, ID 1945-75

85 13338000 South Fork Clearwater River near Grangeville, ID 1911-16,1923-63

86 13338500 South Fork Clearwater River at Stites, ID 1911-12,1965-99

87 13339000 Clearwater River at Kamiah, ID 1910-66

88 13339500 Lolo Creek near Greer, ID 1980-99

89 13340000 Clearwater River at Orofino, ID 1931-38,1965-99

90 14010000 South Fork Walla Walla River near Milton, OR 1903,1906-17,1931-91

91 14011000 NF Walla Walla River near Milton, OR 1930-69

92 12343400 East Fork Bitterroot River near Conner, MT 1956-72

93 12346500 Skalkaho Creek near Hamilton, MT 1949-53,1957-79

94 12351000 Burnt Fork Bitterroot River near Stevensville, MT 1920,1922-24,1938-62

95 13135500 Big Wood River near Ketchum, ID 1948-72

96 13136500 Warm Springs Creek at Guyer Hot Springs near Ketchum, ID 1941-58

97 13139500 Big Wood River at Hailey, ID 1889,1915-99

98 13141000 Big Wood River near Bellevue, ID 1911-96

99 13185000 Boise River near Twin Springs, ID 1911-99

100 13186000 South Fork Boise River near Featherville, ID 1945-99

101 13186500 Lime Creek near Bennett, ID 1945-56

102 13187000 Fall Creek near Anderson Ranch Dam, ID 1945-56

103 13235000 South Fork Payette River at Lowman, ID 1941-99

104 13240000 Lake Fork Payette River above Jumbo Creek near McCall, ID 1946-99

105 13292500 Salmon River near Obsidian, ID 1941-53

106 13293000 Alturas Lake Creek near Obsidian, ID 1941-52

107 13295000 Valley Creek at Stanley, ID 1911-14,1921-73

108 13295500 Salmon River below Valley Creek at Stanley, ID 1925-61

109 13296000 Yankee Fork Salmon River near Clayton, ID 1921-49

110 13296500 Salmon River below Yankee Fork near Clayton, ID 1922-91

111 13308500 Middle Fork Salmon River near Capehorn, ID 1929-72

112 13309000 Bear Valley Creek near Capehorn, ID 1921-60

113 13310000 Big Creek near Big Creek, ID 1945-59

114 13310500 South Fork Salmon River near Knox, ID 1929-61

115 13310700 South Fork Salmon River near Krassel Ranger Station, ID 1967-82,1985-86,1989-99

116 13311000 East Fork South Fork Salmon River at Stibnite, ID 1928-43,1983-97

117 13311500 East Fork South Fork Salmon River near Stibnite, ID 1928-41

118 13312000 East Fork South Fork Salmon River near Yellow Pine, ID 1928-43

119 13313000 Johnson Creek at Yellow Pine, ID 1928-99

120 13314000 South Fork Salmon River near Warren, ID 1931-43

121 13315000 Salmon River near French Creek, ID 1945-56

122 06013500 Big Sheep Creek below Muddy Creek near Dell, MT 1936,1946-53,1960-79

123 06015500 Grasshopper Creek near Dillon, MT 1921-33,1946-54,1955-58,1960-61

124 06019500 Ruby River above Reservoir near Alder, MT 1938-99

125 13108500 Camas Creek at 18-mile Shearing Corral near Kilgore, ID 1937-53,1969-73

126 13112000 Camas Creek at Camas, ID 1925-99

127 13113000 Beaver Creek at Spencer, ID 1941-53,1969-82,1985-93

128 13113500 Beaver Creek at Dubois, ID 1921-73,1983,1985-87

129 13117300 Sawmill Creek near Goldburg, ID 1960-73

130 13120000 NF Big Lost River at Wild Horse near Chilly, ID 1944-99

131 13120500 Big Lost River at Howell Ranch near Chilly, ID 1904-14,1920-99

132 13128900 Lower Cedar Creek above Diversions near Mackay, ID 1966-73,1980-84

133 13297330 Thompson Creek near Clayton, ID 1972-99

134 13297350 Bruno Creek near Clayton, ID 1971-99

135 13297355 Squaw Creek below Bruno Creek near Clayton, ID 1973-99

136 13297450 Little Boulder Creek near Clayton, ID 1970-86

137 13298000 East Fork Salmon River near Clayton, ID 1929-39,1973-82

138 13299000 Challis Creek near Challis, ID 1944-63

139 13302500 Salmon River at Salmon, ID 1912-16,1919-99

140 13305000 Lemhi River near Lemhi, ID 1938-39,1955-63,1967-99

141 13305500 Lemhi River at Salmon, ID 1928-43

142 13306000 NF Salmon River at North Fork, ID 1912,1930-40

143 13306500 Panther Creek near Shoup, ID 1945-78

144 13307000 Salmon River near Shoup, ID 1944-82

Region 4 - Continued

Region 5

Region 6

26 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Appendix A. Selected streamflow-gaging stations and periods of record used in regression analyses--Continued

Map 

number 

(fig. 1)

Gaging 

station 

number Gaging station name

Period of record 

(in water years)

145 10119000 Little Malad River above Elkhorn Reservoir near Malad City, ID 1911-13,1932,1941-69

146 10172940 Dove Creek near Park Valley, UT 1959-68,1971-73

147 10315500 Marys River above Hot Springs Creek near Deeth, NV 1944-99

148 10329500 Martin Creek near Paradise Valley, NV 1922-99

149 10352500 McDermitt Creek near McDermitt, NV 1949-99

150 10353000 East Fork Quinn River near McDermitt, NV 1949-82

151 10396000 Donner Und Blitzen River near Frenchglen, OR 1911-21,1938-99

152 10406500 Trout Creek near Denio, NV 1911-12,1922-23,1925-91

153 13057940 Willow Creek below Tex Creek near Ririe, ID 1977-79,1986-99

154 13075000 Marsh Creek near McCammon, ID 1954-99

155 13083000 Trapper Creek near Oakley, ID 1911-16,1919-99

156 13092000 Rock Creek near Rock Creek, ID 1909-13,1939,1944-75

157 13154000 Clover Creek below Calf Creek near Bliss, ID 1938-43,1957-62

158 13155300 Little Canyon Creek at Stout Crossing near Glenns Ferry, ID 1966-72

159 13162500 East Fork Jarbidge River near Three Creek, ID 1929-33,1954-72

160 13169500 Big Jacks Creek near Bruneau, ID 1938-49,1965-99

161 13170000 Little Jacks Creek near Bruneau, ID 1939-50

162 13172680 Reynolds Creek at Tollgate near Reynolds, ID 1966-99

163 13172720 Reynolds Creek at Macks near Reynolds, ID 1964-91

164 13172735 Reynolds Creek at Salmon near Reynolds, ID 1964-99

165 13172740 Reynolds Creek at Outlet near Reynolds, ID 1963-99

166 13176000 Owyhee River above China Diversion Dam near Owyhee, NV 1939-84

167 13178000 Jordon Creek above Lone Tree Creek near Jordan Valley, OR 1946-53,1955-72

168 13211309 Indian Creek above Waste Water Plant near Nampa, ID 1982-96

169 13226500 Bully Creek at Warmsprings near Vale, OR 1903-07,1910-17,1922-23,1964-86

170 06037500 Madison River near West Yellowstone, MT 1913-73,1983-86,1989-99

171 09223000 Hams Fork Below Pole Creek near Frontier, WY 1952-99

172 10015700 Sulphur Creek below La Chapelle Creek near Evanston, WY 1957-97

173 10040000 Thomas Fork near Geneva, ID 1940-51

174 10041000 Thomas Fork near Wyoming-Idaho State Line 1949-92

175 10058600 Bloomington Creek at Bloomington, ID 1960-86

176 10077000 Soda Creek near Soda Springs, ID 1913-29

177 10093000 Cub River near Preston, ID 1940-52,1955-86

178 10096000 Cub River above Maple Creek near Franklin, ID 1940-52

179 10099000 High Creek near Richmond, UT 1947-52,1971-72,1979-84,1986

180 13010065 Snake River above Jackson Lake at Flagg Ranch, WY 1984-99

181 13011500 Pacific Creek at Moran, WY 1944-75,1978-99

182 13011900 Buffalo Fork above Lava Creek near Moran, WY 1965-99

183 13012000 Buffalo Fork near Moran, WY 1917-18,1945-60

184 13014500 Gros Ventre River at Kelly, WY 1918,1945-58

185 13019438 Little Granite Creek at Mouth near Bondurant, WY 1982-93

186 13019500 Hoback River near Jackson, WY 1917-18,1945-58

187 13023000 Greys River above Reservoir near Alpine, WY 1917-18,1937-39,1954-99

188 13024000 Salt River near Smoot, WY 1932-57

189 13024500 Cottonwood Creek near Smoot, WY 1932-57

190 13025000 Swift Creek near Afton, WY 1942-80

191 13027000 Strawberry Creek near Bedford, WY 1932-43

192 13032000 Bear Creek above Reservoir near Irwin, ID 1917-18,1934-36,1953-72

193 13044500 Warm River at Warm River, ID 1912-15,1918-33

194 13045500 Robinson Creek at Warm River, ID 1912-15,1918-33

195 13046680 Boundary Creek near Bechler Ranger Station Y.N.P., WY 1984-99

196 13047500 Falls River near Squirrel, ID 1902-09,1918-99

197 13049500 Falls River near Chester, ID 1920-99

198 13052200 Teton River above South Leigh Creek near Driggs, ID 1962-99

199 13054000 Teton River near Tetonia, ID 1930-33,1934-37,1940-57

200 13055000 Teton River near St Anthony, ID 1890-93,1903-09,1920-99

Region 8

Region 7

Appendix A 27
Appendix B. Monthly and annual streamflow statistics for selected streamflow-gaging stations

[Q.xx, daily mean discharge exceeded xx percent of the time during the specified month, in cubic feet per second; Qa, mean annual discharge, in cubicfeet per second]

Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 

12305500 11.3 17.5 43.3 14.8 30.9 88.8 17.4 35.8 76.2 17.5 29.6 55.7 17.9 30.4 65.3 25.0 42.7 78.7 89.5 182 365 297 12311000 18.0 26.1 51.8 27.6 42.3 93.5 35.6 57.5 123 34.9 56.4 111 41.8 76.8 137 70.4 125 216 222 368 607 297 12316800 4.4 5.3 6.8 4.5 6.2 11.2 3.7 6.3 13.5 4.0 6.3 11.0 4.6 6.8 13.0 6.4 9.5 23.9 24.3 52.3 93.0 114 12320500 6.9 10.5 26.5 7.6 14.0 42.7 7.2 12.9 30.4 6.9 11.1 22.2 6.9 10.8 19.8 7.9 12.8 21.7 21.1 46.5 106 142 12321000 14.0 32.6 128 24.9 59.3 142 25.3 51.5 106 23.1 38.2 63.6 23.1 35.0 52.4 28.1 44.8 77.8 76.1 165 392 439 12392155 15.7 28.3 134 30.4 136 409 50.7 128 299 66.9 126 262 66.2 125 195 141 268 424 367 681 1290 841 12392300 44.2 63.7 116 61.2 111 200 71.4 122 234 70.3 111 183 78.1 123 251 112 181 338 312 494 762 777 12393500 189 250 450 219 325 690 249 401 813 286 438 722 297 421 670 307 495 716 569 1130 2240 2430 12396000 12.3 15.3 22.7 13.6 18.6 30.0 13.8 22.2 40.2 18.1 25.8 44.9 20.1 35.6 63.0 32.2 55.5 113 117 198 330 139 12408500 10.4 14.4 18.2 12.1 15.1 21.5 11.5 15.4 21.7 10.5 14.7 21.9 12.2 17.4 27.8 18.9 32.5 82.2 71.6 131 232 83.2 12409000 75.1 112 156 101 142 190 104 154 236 106 164 273 140 228 399 247 415 685 433 707 1237 310 12427000 41.4 45.3 50.5 41.6 47.3 52.0 43.4 48.6 54.6 43.4 48.7 58.3 45.9 57.7 71.5 56.6 66.1 80.0 66.7 79.1 102 62.0 12431000 129 157 180 150 180 221 167 207 277 173 222 351 202 329 589 318 510 799 358 560 897 234 12302500 8.1 18.7 40 10.3 24.3 45.3 14.6 22 46.4 13.4 19.0 26.6 11.0 14.9 34.9 13.9 21.7 41.5 51.2 85.3 153 135 12303100 5.9 7.7 11.4 6.7 9.4 15.8 5.9 7.8 12.2 5.0 6.9 10.5 5.0 6.6 11.1 5.7 9.0 14.8 13.0 22.9 44.6 41.6 12303500 110 141 214 119 191 361 132 207 380 113 189 336 130 200 360 165.0 263 438 321 568 851 726 12347500 6.6 16.7 41.7 9.3 17.6 41.2 9.5 16.5 32.2 7.4 11.7 22.3 7.9 13.3 20.7 9.7 15.5 21.8 27.6 52.0 115 127 12350500 11.5 27.3 62.3 13.6 23.6 52.0 10.3 14.5 32.7 8.6 11.7 18.1 9.1 13.2 26.9 12.6 17.8 22.6 31.0 62.8 130 120 12354000 101 121 167 108 153 324 96.5 141 315 107 165 345 133 211 410 169 307 563 618 1070 1770 1290 12389500 150 183 212 150 184 226 136 178 239 129 176 246 144 195 303 185 282 451 387 657 1180 743 12390700 44.3 54.2 62.8 41.7 51.3 86.4 44.1 59.8 156 46.9 73.9 153 53.0 104 206 92.6 177 310 238 414 731 471 12411000 85.2 105 159 101 180 477 135 272 664 147 308 667 209 424 878 349 708 1360 1120 1810 2970 977 12413000 224 282 439 276 524 1280 397 852 2050 430 944 1980 646 1310 2610 1100 2110 3830 2880 4690 7610 2510 12413140 3.2 4.9 6.7 3.6 7.2 17.7 4.3 10.4 27.4 4.4 14.9 35.4 6.7 20.1 42.3 20.1 33.4 65.0 42.9 67.1 117 61.7 12413150 48.7 54.7 65.1 48.5 66.0 113.3 50.6 79.0 139 45.9 92.2 169 60.9 110 169 104 170 318 210 380 615 455 12413210 63.7 75.5 97.5 73.1 115 208 87.0 134.4 291 82.9 157 316 85.5 216 385 214 344 569 409 576 1060 526 12413470 89 106 152 110 182 370 138 248 497 141 291 573 157 419 872 404 635 969 684 1100 1820 791 12413500 316 403 665 378 692 1780 533 1060 2510 554 1200 2590 687 1630 3520 1390 2710 4870 3920 6400 10300 3560 12414500 348 432 623 369 604 1330 415 740 1730 420 788 1680 534 1070 1960 898 1660 3010 2670 4550 7660 4810 12414900 51.9 63.0 86.7 61.4 95.8 179 75.0 123 277 93.3 188 494 140 305 699 298 534 1010 425 728 1280 311 12415000 53.8 75.2 137 67.7 119 296 81.9 191 500 101 193 565 128 376 1010 311 734 1430 849 1500 2470 502 12416000 3.7 4.8 6.4 4.2 6.6 13.8 4.8 9.2 27.4 5.5 13.2 39.7 8.5 25.4 55.0 24.7 40.1 78.6 34.2 61.1 119 22.8 13336500 525 740 1190 630 970 1720 658 983 1750 666 975 1750 761 1190 1990 1190 1870 3000 2970 4800 8910 8010 13336900 34.2 49.9 77.6 46.8 69.7 198 48.8 79.4 220 46.9 88.4 158 58.2 131.1 233 87.3 170 257 347 529 826 678 13337000 385 558 959 486 796 1510 520 814 1540 540 840 1560 610 984 1700 972 1550 2480 2470 4100 698 6340 13340500 587 782 1190 693 1010 1800 680 1020 1860 681 1080 1730 821 1190 2060 1000 1510 2300 2640 4400 7250 7200 13340600 742 873 1230 830 1240 2120 834 1220 2140 860 1370 2440 1030 1690 2800 1770 2740 4400 3600 5440 8900 6820 13341300 0.9 1.3 2.1 1.3 1.8 3.3 1.6 2.3 3.9 1.7 2.7 6.2 2.4 5.2 10.8 2.9 5.6 11.3 8.3 12.9 22.6 3.9 13341400 9.2 12.2 21.1 12.5 17.8 39.4 15.2 27.2 52.7 16.8 35.1 76.4 22.6 63.1 130.2 41.6 77.3 160 114 181 284 47.7 12424000 8.8 17.6 25.6 17.4 27.3 45.6 29.1 60.5 211 41 140 617 120 359 1070 193 448 1110 124 254 522 53.2 13334700 35.4 38.8 42.6 38.2 42.6 48.6 41 49.7 73.9 41.1 53.8 100 48.3 70.3 106 56.5 77.3 110 68.2 100 155 88.2 13345000 9.1 14.0 24.1 15.3 30.6 74.2 26.6 58.4 198 36.7 130 499 94.1 303 800 242 532 1170 224 531 1100 91.5 13346100 12.4 18.8 30.5 22.2 37.5 64.6 30.2 64.4 255 52.4 188 629 118 349 913 253 518 1040 212 621 1140 90.0 13346800 0.2 0.3 1.1 0.3 1.0 3.2 0.7 1.7 4.9 1.3 5.1 16.5 3.7 11.0 30.7 5.8 14.2 26.7 3.2 6.3 12.9 1.3 13348000 1.8 3.7 5.4 2.9 4.8 9.5 4.7 11.6 36.8 7.0 25.9 96.1 23.9 58.5 154 32.1 75.3 166 22.1 42.4 82.4 7.8 13348500 0 0.2 0.5 0.1 0.5 1.0 0.2 1.0 5.3 0.8 4.7 21.2 3.1 11.8 37.1 3.8 15.4 41.5 1.7 4.6 13.2 0.3 13341500 14.3 25.6 54.0 27.0 62.5 185 43.3 137 435 49 152 624 150 388 1400 403 891 1830 697 1250 1980 167 13342450 7.6 14.4 21.8 13.9 20.6 33.5 18.2 30.3 60.4 22 34.7 119 28.9 69.2 162 57.1 144 302 76.8 154 362 34.4 13196500 0.4 0.6 0.8 0.5 0.7 1.0 0.6 0.8 1.1 0.6 0.8 1.4 0.7 1.1 2.0 0.9 1.6 3.1 2.9 4.7 11.6 2.8 13200000 41.5 55.7 78.8 57.4 80.1 115 60.5 91.8 146 67.2 107 188 93.4 155 329 172 323 732 345 805 1430 376 13200500 1.5 2.0 3.0 2.3 3.0 4.1 2.4 3.5 5.4 2.8 4.1 9.2 4.4 8.0 16.6 6.5 11.6 21.2 10.7 21.6 48.3 5.4 13201000 42.1 56.4 79.4 60.7 83.5 117 59.8 93.7 159 67.7 93.8 163 89.2 155 282 179 337 730 538 986 1610 456 13207000 0 0 0 0 0.1 0.1 0 0.1 0.7 0.1 0.8 7.4 0.8 2.7 11.5 0.8 4.5 10.3 0.4 3.5 12.1 0 13207500 0.3 0.8 1.4 0.8 1.4 2.0 1.0 1.7 3.8 1.3 2.4 7.5 3.9 6.9 20.7 4.0 10.2 29.6 1.3 8.2 40.0 0.2 13216500 43.4 51.4 61.1 45.3 55.6 67.3 41.3 53.4 72.7 41.9 54.7 77.2 51.3 71.0 137 81.2 149 327 159 306 583 147 13250600 5.4 5.9 6.6 6.0 7.0 9.8 6.5 12.3 40.9 7.0 19.2 73.5 13.8 31.2 74.9 17.1 40.6 77.0 11.5 25.6 58.6 6.0 13251300 1.0 1.3 1.6 1.1 1.4 2.2 1.0 1.3 2.4 0.9 1.3 2.4 1.1 1.6 3.5 1.5 2.6 6.1 9.3 15.1 25.1 9.3 13251500 5.4 6.8 9.0 6.1 8.0 13.1 6.2 8.6 21.0 6.1 9.9 22.3 6.9 15.4 29.3 13.6 29.5 84.8 109 191 324 50.9 13253500 17.8 21 30.7 27.7 34.1 47.9 29.2 38.7 73.6 32.7 46.5 75.3 37.1 49.3 71.2 58.0 112 285 292 426 708 155 13256000 51.6 64.9 101 70 95.3 150 74.7 121 304 82.1 169 276 130 249 499 266 618 1110 824 1290 2180 555 13257000 12.8 19.7 32 20.4 30.5 53.7 25.4 36.4 93.3 27.1 41.3 58.5 32.5 58.8 105 60.6 108 178 130 218 376 281 13258500 68.9 96.3 140 92.5 133 228 106 177 439 122 226 514 198 413 937 472 932 1680 915 1510 2440 1020 13260000 6.1 9.1 12.1 9.8 12.8 16.2 10.4 13.3 19.2 10.4 13.9 23.2 12.5 26.1 47.7 28.5 52.2 98.3 51.2 81.6 119 67.7 13261000 10.7 13.5 18.5 13.5 20.1 34.1 15.4 23.8 56.3 17.1 30.9 74.3 27 56.5 104 43.7 75.9 131 118 196 325 219 13266000 115 165 236 146 201 361 163 268 702 203 379 1080 307 788 2120 843 1780 3610 1280 2220 3470 1540 13267000 2.8 4.0 5.7 4.3 6.0 9.1 4.8 7.1 13.4 6.0 9.5 21.0 8.3 22.2 43.8 25.6 61.0 125 89.2 148 240 46.4 13269300 1.5 2.4 3.9 3.0 4.5 7.6 3.2 7.1 15.3 5.7 9.0 21.7 8.0 15.2 52.6 23.3 64.5 164 75.4 186 338 44.7 13270800 19.8 22.5 24.7 19.4 22.1 24.1 19.1 20.9 23.8 19.0 21.1 23.2 19.5 21.3 22.8 20.8 22.8 26.4 24.7 31.1 45.3 32.1 

Gaging Jan Feb Mar Apr 

station

number

Oct Nov Dec

Region 1 Region 2 Region 3 Region 4 

Appendix A 25
Appendix B. Monthly and annual streamflow statistics for selected streamflow-gaging stations--Continued

Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 

13275500 7.2 12.5 22.8 12.1 22.3 37.5 16.0 26.7 47.6 17.2 28.4 52.6 24.4 44.7 83.2 54.4 105 212 152 292 541 198 13288200 77.0 96.1 116 84.6 107 147 78.4 100 136 75.3 98.8 129 81.9 108 150 111 154 254 237 378 557 538 13289960 16.6 29.5 38.8 24.1 30.3 44.5 24.3 31.9 57.6 25.2 35.3 75.0 32.7 56.2 193 105 205 416 196 316 528 178 13290190 40.4 66.0 90.1 69.5 99.0 155 82.3 130 292 84.7 149 299 132 232 522 297 510 859 372 616 935 497 13315500 1.7 2.1 2.8 1.9 2.8 4.2 2.2 2.8 5.9 2.2 3.2 6.8 2.5 4.2 6.4 3.8 8.9 20.2 38.8 85.4 151 28.7 13316500 169 213 276 178 237 342 172 232 397 168 242 379 195 293 531 315 529 943 778 1200 1820 1410 13316800 1.5 2.6 5.8 2.4 3.9 8.0 2.1 4.8 9.1 2.0 4.3 10.5 3.5 7.0 15.3 5.5 9.1 18.5 20.6 32.5 51.0 46.5 13317000 3740 4680 5670 3900 4720 5830 3380 4220 5280 3280 3940 4940 3520 4190 5070 4000 4940 6580 6340 9420 16600 17600 13319000 25.9 36.3 51.8 34.8 51.8 110 37.4 74.9 234 45.9 102 279 73.2 184 480 254 563 1200 659 1120 1930 516 13320000 24.0 28.7 36.8 25.5 33.2 46.9 25.1 34.5 54.5 25.5 37.4 57.9 28.4 45.9 72.9 47.5 76.0 139 121 214 336 247 13323600 2.9 4.2 7.0 3.7 5.2 9.7 3.8 6.0 14.8 4.0 6.0 10.2 4.0 6.7 11.6 6.6 12.9 20.9 30.5 43.5 108 104 13329500 23.4 29.1 37.9 21.6 26.9 40.3 18.5 24.3 34.7 15.5 21.4 28.7 14.5 19.7 26.0 14.2 20.1 25.1 21.8 34.1 67.0 83.6 13330000 31.7 43.0 68.5 32.3 49.1 82.6 28.3 43.5 79.0 28.1 40.9 66.9 27.4 40.9 60.2 33.8 48.4 70.0 64.1 119 239 245 13330500 10.4 15.7 32.6 15.3 26.7 52.2 16.4 32.1 70.3 16.6 32.4 62.5 20.5 34.4 65.5 33.1 54.6 93.1 72.0 136 254 209 13331500 67.8 86.4 120 77.7 120 181 78.6 130 234 88.9 160 285 116 193 331 187 267 437 291 447 744 719 13337500 40.0 56.9 81.0 49.4 72.7 114 46.8 71.8 120 46.2 71.8 122 54.8 80.9 145 77.7 135 236 314 583 976 720 13338000 148 213 333 167 246 395 161 238 417 159 219 379 185 262 432 280 422 736 996 1800 2830 2100 13338500 174 247 350 221 298 454 217 288 464 226 350 740 268 441 844 514 798 1430 1190 1830 2860 1850 13339000 1180 1740 2890 1440 2200 4050 1440 2190 4420 1450 2090 4030 1730 2600 4850 2520 4160 6940 7690 12700 21200 18900 13339500 39.9 60.9 107 64.0 118 215 91.6 125 219 90.5 144 332 129 257 638 328 541 916 541 783 1180 411 13340000 1230 1810 2680 1590 2540 4220 1650 2510 4330 1780 2780 6190 2030 3590 7300 4320 6690 10800 8680 13300 21900 17700 14010000 92.9 107 125 102 124 155 110 138 191 115 144 208 126 161 230 151 195 263 204 259 347 213 14011000 5.7 7.3 11.7 9.4 16.1 36.8 13.4 31.0 69.9 16.9 33.5 72.7 25.7 45.2 89.0 36.2 62.6 113 71.8 107 163 44.6 12343400 91.1 108 132 82.4 102 125 68.2 87.6 112 69.9 82.7 102 72.1 82.7 109 79.2 96.1 138 133 203 316 478 12346500 33.7 41.1 47.9 30.0 34.7 41.4 25.0 28.9 35.1 22.2 26 31.5 22.3 25.5 28.9 22.6 25.6 29.4 28.1 39.1 73.0 93.6 12351000 17.0 20.2 25.2 17.5 20.9 27.2 16.3 19.6 23.9 13.8 17.0 19.7 13.4 16.3 20.1 13.6 16.0 19.7 19.4 31.3 64.0 63.2 13135500 59.8 72.6 82.3 53.0 64.3 72.8 42.8 53.4 64.4 42.5 50.2 57.8 42.0 48.3 54.4 42.9 47.6 54.5 60.2 99.3 230 235 13136500 33.9 37.3 42.3 32.3 35.6 40.0 30.0 33.9 37.7 29.0 33.1 36.1 28.2 31.0 34.3 29.5 33.1 37.9 48.0 87.0 198 166 13139500 20.1 158 246 14.3 147 219 7.7 127 180 5.5 129 176 4.8 128 169 11.3 144 208 181 364 719 577 13141000 49.0 88.2 152 48.3 100 163 44.0 74.5 126 37.5 58.4 94.7 36.8 60.6 107 46.1 99.4 164 109 284 619 239 13185000 303 371 459 320 394 519 300 389 547 308 395 527 333 435 607 450 683 1110 1110 1790 3010 2170 13186000 194 235 290 197 241 298 179 226 284 188 228 285 202 238 307 243 332 486 555 993 1900 1360 13186500 20.6 25.9 31.4 24.3 29.0 38.7 24.4 31.0 40.8 26.5 33.6 42.5 28.2 39.0 50.0 35.2 50.9 77.1 118 246 527 182 13187000 13.8 16.8 19.2 15.6 18.4 24.1 16.0 19.3 26.6 16.8 21.5 28.4 18.3 22.9 32.2 21.8 30.2 50.8 73.7 196 369 171 13235000 305 350 420 293 346 424 266 325 411 258 315 386 265 314 396 308 389 536 533 844 1440 1280 13240000 13.6 20.8 36.1 16.5 28.6 64.8 17.0 28.3 59.1 18.2 27.7 49.1 19.9 30.1 45.8 23.9 33.9 54.5 50.0 98.3 231 251 13292500 32.2 40.2 51.7 31.5 38.1 52.1 25.3 30.4 41.1 22.5 26.3 35.0 21.3 24.4 25.9 21.5 25.3 30.4 28.4 35.9 92.0 131 13293000 14.4 17.9 28.2 17.8 21.9 28.9 18.3 21.4 29.3 17.3 20.5 22.9 16.2 19.0 23.6 15.9 18.3 23.3 20.6 30.2 75.4 109 13295000 76.0 93.0 117 77.7 91.9 116 69.1 83.7 103 65.8 81.0 98.3 67.2 79.5 94.5 72.8 83.9 95.8 97.4 161 310 340 13295500 281 363 462 290 367 456 259 330 395 256 312 376 255 309 361 270 309 354 332 502 894 967 13296000 51.4 66.1 78.0 46.2 58.7 71.2 42.0 51.9 63.5 39.1 45.4 55.9 40.3 45.2 50.4 41.6 50.5 59.5 63.5 131 346 365 13296500 392 491 613 388 480 592 355 434 513 340 401 471 347 398 458 357 406 469 475 720 1320 1450 13308500 81.8 94.9 115 72.9 89.5 104 65.5 77.2 91.1 62.0 72.6 84.2 60.9 69.2 79.3 62.6 70.8 77.5 75.9 111 250 411 13309000 91.7 109 140 88.9 106 135 80.1 99.5 114 76.9 90.5 108 76.2 90.0 103 81.8 93.4 107 106 189 408 564 13310000 153 173 218 133 156 196 120 142 173 114 130 150 111 126 141 114 138 158 173 320 790 918 13310500 34.6 42.0 52.7 35 44.9 57.6 33.5 42.4 54.5 34.2 41.0 50.9 34.2 40.5 49.4 36.3 46.8 60.1 63.7 148 310 307 13310700 120 143 172 126 153 229 121 157 287 118 165 280 122 167 300 153 233 411 293 530 1010 936 13311000 7.1 10.1 13.3 7.0 8.9 11.6 6.2 8.0 9.5 6.0 7.0 8.3 6.1 7.0 8.0 6.3 7.5 9.2 8.5 15.9 29.5 34.9 13311500 16.3 19.6 22.7 14.7 18.2 19.7 13.4 16.9 20.5 12.4 14.8 17.7 12.7 14.3 16.7 12.8 14.9 20.7 18.2 42.0 69.9 106 13312000 44.8 53.0 65.0 36.8 46.1 57.9 35.3 44.4 51.8 30.9 40.2 50.8 30.8 37.6 50.2 34.6 40.5 58.1 54.8 120 257 268 13313000 65.7 88.6 114 65.7 88.8 120 61.7 80.1 114 63.4 76.9 107 62 75.9 100 67.0 83.0 120 111 203 467 618 13314000 362 464 594 365 510 652 352 478 679 367 439 615 364 450 617 416 607 790 894 1990 3950 3570 13315000 3680 4040 5180 3800 4300 5070 3070 3820 4760 3070 3550 4300 3160 3640 4250 3430 4000 5050 4680 7950 15900 17800 06013500 50.0 63.2 74.2 46.0 56.9 66.3 40.6 48.3 54.7 37.9 42.4 49.5 36.8 40.8 47.4 37.5 43.0 50.8 49.0 71.5 115 44.4 06015500 22.2 36.1 48.0 30.7 39.8 49.7 20.2 25.8 38.8 16.0 20.8 30.3 15.7 24.7 32.9 23.9 33.3 54.1 48.0 69.8 96.1 51.3 06019500 103 120 143 108 122 139 97.7 110 124 90.1 103 117 91.0 102 114 93.6 106 122 112 141 206 224 13108500 19.3 23.6 38.0 21.0 30.4 38.3 16.8 24.2 30.3 13.2 19.0 25.0 13.2 19.6 25.9 12.2 19.6 31.0 34.8 95.8 320 144 13112000 0 0.6 10.9 0.1 2.8 13.8 0.1 2.1 9.3 0 2.1 7.5 0 1.8 8.0 0.2 3.6 12.5 11.0 46.2 145 40.5 13113000 7.2 17.8 26.8 10.3 16.6 25.0 7.3 13.8 20.7 7.1 13.1 19.1 7.3 13.7 20.4 11.1 19.8 28.9 30.7 69.8 135 43.1 13113500 0 0.1 15.0 0 0.1 18.4 0 0.4 13.2 0 0.1 11.5 0 0.8 14.4 0.1 5.9 19.4 9.6 40.5 104 11.5 13117300 16.4 21.5 27.9 15.6 18.6 24.0 13.8 16.0 19.3 13.9 16.2 19.4 14.7 17.2 19.7 14.0 16.9 23.2 17.9 24.4 46.3 56.4 13120000 29.5 37.7 48.6 23.9 30.5 36.9 20.8 24.7 29.6 19.3 23.0 27.5 18.5 21.2 24.5 17.8 20.8 25.5 25.3 43.6 89.6 113 13120500 88.1 123 160 76.9 103 127 65.8 83.3 104 64.3 78.9 97.8 63.4 75.6 89.4 64.7 76.3 92.8 80.5 132 258 329 13128900 8.6 11.3 15.0 7.1 8.1 11.1 5.5 6.6 7.7 4.5 5.6 7.3 3.8 4.8 6.9 3.1 4.3 5.6 2.8 4.1 7.2 9.6 13297330 3.6 4.8 6.5 3.4 4.6 6.4 3.3 4.1 5.4 3.1 3.8 5.3 3.2 3.9 5.7 4.1 6.2 11.1 9.0 18.5 39.0 26.6 13297350 0.2 0.3 0.6 0.2 0.3 0.5 0.2 0.3 0.4 0.2 0.3 0.4 0.2 0.3 0.5 0.2 0.4 0.6 0.4 0.7 1.7 0.6 13297355 7.4 11.6 15.0 7.4 11.2 15.2 7.5 9.6 14.8 7.2 9.0 14.1 7.1 9.5 14.2 9.9 13.8 19.8 18.7 33.1 62.8 46.9 13297450 6.3 9.1 12.3 5.7 7.8 9.9 5.3 6.8 8.2 4.7 5.9 7.4 4.3 5.3 7.1 4.5 5.3 7.0 5.5 6.7 11.3 13.5 13298000 84.9 108 154 80.3 98.6 129 61.8 82.7 109 60.3 74.7 100 65.3 77.0 93.2 71.0 81.5 102 84.4 112 183 192 13299000 19.3 22.4 25.9 16.2 19.6 22.0 12.3 15.3 17.8 9.7 13.2 15.9 9.6 12.6 15.1 9.7 13.4 16.1 14.6 21.5 40.9 50.1 13302500 1000 1270 1540 1100 1310 1510 924 1150 1360 890 1060 1260 921 1090 1230 969 1110 1250 1100 1410 2150 2130 13305000 196 252 319 227 272 331 200 231 275 188 222 266 199 232 275 214 254 291 199 259 313 162 13305500 174 229 302 222 266 312 177 218 260 167 202 242 186 210 256 197 233 271 203 246 337 118 

Region 5 

Region 6 

Gaging Mar Apr station 

number

Oct Nov Dec 

Region 4--Continued 

Jan Feb 
Appendix B. Monthly and annual streamflow statistics for selected streamflow-gaging stations--Continued

Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 Q.80 Q.50 Q.20 

13306000 30.8 39.8 45.8 35.3 42.1 47.4 29.6 37.5 44.4 30.2 33.8 40.6 30.5 35.2 38.4 35.5 39.9 49.7 13306500 90.8 104 126 81.4 101 116 72.8 87.3 103 68.7 82.4 94.5 72.3 79.0 92.4 73.6 85.2 98.4 13307000 1630 1940 2300 1780 2020 2240 1550 1800 2010 1440 1670 1920 1520 1680 1870 1530 1680 1920 10119000 11.9 14.5 16.5 12.3 14.5 16.8 12.5 14.3 17.0 12.5 14.6 17.1 12.8 15.6 19.2 14.2 18.0 24.1 10172940 0.2 0.3 0.7 0.2 0.4 0.6 0.2 0.3 0.5 0.2 0.2 0.7 0.2 0.4 0.8 0.3 0.6 1.2 10315500 1.8 3.0 9.2 4.0 9.6 19.4 8.1 13.0 21.9 8.8 14.4 26.7 14.9 24.1 45.7 31.0 56.9 102 10329500 6.3 7.2 8.9 6.8 9.0 11.3 7.2 9.2 12.4 7.4 9.9 14.0 9.2 13.7 30.6 15.6 30.2 83.4 10352500 2.3 3.7 6.4 4.5 6.2 8.7 4.8 7.4 12.4 5.4 8.7 18.7 8.4 18.1 42.4 12.8 36.1 132 10353000 2.4 3.2 4.2 3.4 4.6 6.3 3.6 5.4 9.2 4.0 6.2 19.0 6.8 14.4 29.5 12.6 26.5 72.0 10396000 34 43.8 52.4 35.6 46.3 57.5 33.0 45.4 59.6 33.6 45.5 71.9 39.6 53.4 102 53.1 92.9 212 10406500 3.4 5.1 6.1 4.3 5.9 7.7 4.4 5.5 7.7 4.0 5.8 8.5 4.7 6.8 10.9 5.7 9.3 19.4 13057940 21.7 38.3 60.6 25.9 43.1 63.0 25.0 42.4 59 26.6 39.9 56.4 31.8 45.8 61.3 49.9 67.4 127 13075000 62.2 75.5 95.2 64.2 78.6 100 60.9 75.1 97.6 59 74.6 96.5 65.7 87.9 122 77.7 105 156 13083000 9.4 11.2 12.9 9.9 11.7 13.3 9.6 11.8 13.6 9.4 11.5 13.9 10.5 12.2 14.7 11.7 14.2 18.1 13092000 8.1 9.6 12.2 9.5 11.5 13.9 9.7 12.4 16.0 9.7 12.9 18.9 12.0 16.0 23.6 14.9 21.7 36.7 13154000 2.2 2.8 3.6 3.2 3.8 5.4 3.6 4.9 14.4 5.0 7.0 11.7 8.3 24.6 89.4 20 61.3 171 13155300 0.6 1.2 1.6 0.8 1.2 1.5 0.9 1.2 2.0 1.2 2.2 11.3 1.6 5.5 18.1 5.7 10.0 17.5 13162500 7.9 10.9 15.3 8.5 11.0 14.3 8.1 9.9 13.2 7.8 9.3 12.9 8.5 11.1 20.9 11.9 18.5 27.4 13169500 0 0 1.5 0 0 1.7 0 0 0.6 0 0 1 0 0 5.5 0 2.3 30.0 

13170000 0.1 0.2 0.3 0 0 0 0 0 0 0 0.1 0.1 0 0.1 0.3 0 0.1 2.6 13172680 0.5 1.4 2.1 1.3 2.0 3.4 1.5 2.3 5.6 1.7 3.2 9.7 2.2 5.5 13.4 5.3 11.3 37.4 13172720 0 0 0.2 0 0.2 0.7 0.1 0.5 1.7 0.5 1.2 4.7 0.8 2.5 6.1 1.6 4.0 13.5 13172735 0.1 0.3 0.9 0.3 0.7 1.3 0.7 1.3 2.9 1.0 2.1 5.2 1.4 3.2 7.0 2.2 4.8 11.3 13172740 0.8 1.3 3.7 1.0 2.6 5.5 2.2 3.8 11.8 3.0 6.9 27.4 4.4 12.6 34.4 6.6 21.0 67.1 

13176000 16.5 26.3 41.8 18.5 25.4 37 17.6 24.3 41.8 18.3 30.4 67.7 25.2 46.1 104 41.6 94.0 212 13178000 3.3 9.2 18.6 14.8 21.1 32 17.6 27.9 53.5 20 34.7 161 35.6 96.5 266 90.8 181 395 13211309 32.5 43.5 56.8 31.7 37 45.3 28.0 33.2 38.3 24.3 29.5 33.1 21.9 26.3 32.2 23.3 26.8 34.0 13226500 2.1 3.8 9.4 3.6 7.3 12.6 5.6 10.5 28.2 8.0 18.5 77.6 15.4 55.8 157 36.4 93.8 278 06037500 358 422 500 365 417 484 352 415 467 347 403 455 352 396 438 360 402 449 09223000 16.4 21.0 27.4 15.1 19.5 24.7 12.8 15.9 21.0 11.5 14.7 19.1 11.5 15.4 19.7 14.4 19.2 25.2 10015700 0.2 0.9 6.6 0.6 3.2 8.7 1.0 3.5 7.7 1.5 3.7 7.3 2.4 4.4 7.7 3.5 8.4 28.4 10040000 3.0 4.5 5.5 2.6 4.1 4.9 2.1 3.5 4.5 2.1 3.0 4.2 2.0 2.6 3.7 2.4 3.3 5.1 10041000 13.1 17.8 23.9 12.7 16.6 21.0 11.4 15.3 19.0 11.5 14.8 18.1 12.4 14.8 17.9 13.7 16.6 23.9 10058600 18.2 21.1 24.9 16.8 18.9 22.5 16.1 17.5 20.7 14.5 16.5 19.2 14.2 16.1 18.4 14.5 16.4 19.1 10077000 48.5 58.4 67.9 49.5 58.6 68.6 48.1 54.2 60.9 44.3 49.6 60.1 46 49.8 58.0 47.0 54.1 68.3 10093000 25.4 28.9 32.6 22.3 25.5 28.4 19.7 22.8 26.8 18.3 20.5 25.6 17.3 20.1 26.4 20.1 25.6 37.5 10096000 3.0 4.5 16.5 3.4 4.6 15.7 9.2 15.9 31.2 15.2 26.5 33.4 22.4 28.8 34.7 23.3 35.5 59.5 10099000 9.4 11.4 14.5 8.1 11.3 14 8.0 9.2 13.1 6.9 9.0 12.4 6.8 10.5 14.5 9.1 15.6 24.9 13010065 262 361 433 257 362 454 296 359 446 292 339 422 288 349 424 310 355 402 13011500 50 61.2 79.2 42.2 52.8 65.3 37.3 47.2 58.7 34.9 44.8 55.7 36.7 46.1 55.6 41.9 50.4 62.5 13011900 171 215 261 144 172 200 120 140 161 106 122 141 104 117 129 110 123 142 13012000 186 213 272 157 178 208 130 154 172 121 133 152 121 130 150 121 140 150 13014500 174 207 236 158 178 204 142 160 184 138 148 165 135 144 161 136 145 161 13019438 5.5 7.3 11.3 5.2 6.7 9.3 4.6 5.6 7.6 3.8 4.9 6.5 3.9 5.1 6.3 4.8 6.6 8.9 13019500 238 264 308 200 229 258 178 204 237 177 193 220 171 190 207 166 187 208 13023000 251 309 387 220 262 320 186 226 271 177 209 256 176 202 236 184 215 262 13024000 6.8 10.3 13.2 5.7 8.4 11.9 4.8 7.5 9.1 4.0 6.4 9.2 3.8 5.9 9.1 6.0 7.8 9.6 13024500 20.2 23.1 27.0 16.8 19.3 22.4 15.2 17.3 19.5 13.6 15.4 17.5 12.3 14.1 16.2 11.7 13.4 15.3 13025000 44.7 49.5 55.7 39.5 44.4 49.1 36.5 39.8 44.7 34.3 37.4 41.9 32.4 35.5 38.5 32.2 34.8 37.4 13027000 42.4 46.0 50.0 36.5 41.5 45.4 32.8 37.8 40.9 30.9 34.4 36.3 28.9 32.1 34.6 27.4 30.6 32.1 13032000 24.9 28.4 32.2 22.3 25.1 28.9 19.8 22.7 26.6 18.1 21.5 26.7 16.9 20.8 28.2 18.8 24.0 30.9 13044500 196 215 230 187 208 230 179 200 219 181 199 215 184 198 215 179 198 216 13045500 63.8 77.6 99.8 61.0 76.1 96.9 55.3 71.2 87.7 51.2 65.0 75.3 52.4 61.7 72.0 54.5 66.2 82.0 13046680 65.5 83.4 97.4 67.4 79.8 96.9 64.4 78.0 93.1 61.6 73.5 85.2 60.9 69.8 82.4 62.6 69.2 82.6 13047500 391 483 572 385 470 546 353 438 499 332 406 457 343 389 435 352 391 434 13049500 311 452 596 423 523 644 431 514 607 410 474 557 414 466 528 419 470 547 13052200 241 317 390 211 286 345 177 224 277 165 200 246 167 208 252 198 239 332 13054000 279 321 378 257 288 348 198 230 267 177 205 229 181 208 232 177 218 285 13055000 460 544 656 413 489 579 353 418 480 327 384 439 333 385 448 367 430 541 

Region 7 Region 8 

Mar 

Gaging station 

number

Oct Nov Dec 

Region 6--Continued 

Jan Feb 
Appendix C. Basin characteristics for selected streamflow-gaging stations

[A, drainage area, in square miles; E, mean basin elevation, in feet above sea level; BR, basin relief, in feet; S30, slopes greater than

30 percent, in percent of drainage area; P, mean annual precipitation, in inches; F, forested area, in percent of drainage area; BS, basin slope, in percent;

MCS, main channel slope, in feet per mile]

Gaging 

station 

number A E BR S30 P F BS MCS 

12305500 55.3 4686.9 4134.8 69.4 48.3 91.9 37.1 140.1

12311000 133.1 3257.0 5376.7 27.0 30.4 72.6 21.2 19.6

12316800 12.5 4084.4 3178.5 33.2 29.1 94.5 25.4 265.6

12320500 29.9 5347.3 5803.1 81.4 41.3 89.5 46.4 206.9

12321000 71.1 5054.2 5866.9 62.3 46.1 70.4 37.0 151.0

12392155 115.1 4648.5 4844.3 71.8 54.3 82.4 43.2 128.3

12392300 121.4 4280.6 5441.4 52.4 38.1 62.6 32.2 126.9

12393500 596.6 3941.3 5124.1 46.3 38.8 79.0 28.9 13.1

12396000 68.2 3622.5 3731.6 51.8 36.7 79.6 30.1 96.6

12408500 82.5 3520.8 3832.5 46.2 37.7 89.4 29.6 105.0

12409000 1011.0 2904.3 5308.7 29.2 27.6 76.9 22.3 11.1

12427000 84.4 2459.0 2230.6 10.4 28.2 65.2 13.2 30.4

12431000 634.9 2397.7 4281.5 9.4 25.1 54.6 12.2 25.9

12302500 23.7 5275.3 5917.3 82.4 53.0 66.4 54.1 246.0

12303100 11.3 5466.8 4788.9 71.2 52.6 76.7 48.3 466.2

12303500 125.0 4069.2 5752.5 62.8 43.9 87.3 38.5 76.9

12347500 26.1 6649.7 4871.1 83.8 60.9 50.3 57.0 156.6

12350500 29.0 6557.7 5711.5 89.6 55.6 60.4 58.8 289.4

12354000 43.6 4843.4 4434.8 84.6 44.5 88.3 47.2 180.4

12389500 641.5 4567.1 4998.9 47.0 29.6 85.8 30.0 18.5

12390700 181.5 4437.3 4349.7 79.6 43.7 93.1 43.5 79.3

12411000 334.0 3947.0 3722.1 75.6 48.2 89.7 40.8 29.8

12413000 893.7 3835.9 4637.1 77.6 45.4 88.9 41.9 20.8

12413140 15.0 4411.0 3461.3 88.8 41.5 94.2 49.6 217.1

12413150 105.6 4615.4 4133.8 82.3 42.5 89.8 45.8 84.2

12413210 181.8 4301.2 4438.3 82.5 43.3 88.4 45.8 62.8

12413470 287.1 4096.4 4605.6 80.7 45.1 83.5 44.6 50.8

12413500 1207.4 3878.0 4673.2 77.8 45.0 87.3 42.3 19.5

12414500 1024.5 4545.6 5487.6 74.4 47.0 89.8 41.3 29.2

12414900 272.6 3592.6 3792.4 34.9 37.7 80.5 25.1 34.8

12415000 434.5 3465.5 4214.6 31.7 35.6 82.2 23.8 26.7

12416000 21.5 3564.7 3243.5 81.2 38.8 95.1 41.8 242.0

13336500 1913.1 5511.8 7789.6 75.6 40.6 82.8 44.2 39.8

13336900 88.3 4467.2 4633.9 55.7 46.3 91.3 34.7 159.2

13337000 1179.4 5197.2 7331.2 63.5 46.6 88.2 38.5 43.0

13340500 997.5 4888.8 5663.4 68.1 52.5 82.1 39.0 43.1

13340600 1294.2 4732.9 6182.5 69.9 51.4 82.9 40.4 34.1

13341300 3.0 3716.0 1643.9 55.6 48.1 86.8 32.0 282.7

13341400 42.7 3617.2 2146.1 36.4 42.7 86.0 26.3 63.4

12424000 674.9 2647.1 3187.9 6.8 20.8 19.4 10.5 13.0

13334700 170.5 3752.2 5098.9 57.5 23.0 30.5 35.4 121.9

13345000 316.0 3165.1 2859.7 25.8 30.1 63.4 21.2 17.4

13346100 491.7 2963.6 3350.1 17.8 26.9 41.7 17.7 11.8

13346800 17.6 2844.2 1801.2 6.0 24.5 12.5 11.8 32.9

13348000 126.9 2745.5 2637.5 3.3 23.8 6.9 11.9 21.4

13348500 27.1 2652.2 1442.8 0.1 23.2 0.6 10.0 26.0

13341500 453.7 2969.1 3849.7 17.8 29.5 59.8 18.2 46.5

13342450 268.9 3149.2 4100.8 22.2 19.3 30.7 18.9 139.3

13196500 4.8 5313.2 2396.4 57.4 22.1 60.4 32.9 318.3

13200000 397.0 5070.8 5019.7 51.0 24.8 66.3 31.3 83.3

13200500 16.0 4680.6 3410.5 70.6 23.3 65.0 39.8 317.0

13201000 424.4 5024.2 5068.8 52.0 24.5 65.0 31.7 71.8

13207000 19.2 4017.4 3094.6 30.2 19.4 8.0 24.3 197.1

13207500 59.4 3963.4 4310.5 34.3 20.4 11.7 25.3 162.8

13216500 342.5 5360.8 4668.1 23.2 23.8 52.7 21.6 58.1

13250600 55.2 4099.3 2987.5 28.0 15.9 4.8 23.6 76.7

13251300 4.0 4947.6 1821.4 41.5 39.8 81.5 27.3 328.9

13251500 36.6 4654.2 1896.9 27.1 34.6 87.8 22.3 53.8

13253500 105.4 4969.7 4662.7 38.0 32.3 88.1 26.5 53.7

13256000 391.9 4668.2 5242.5 32.7 29.6 64.6 24.2 41.4

13257000 86.1 5430.2 5221.5 38.3 34.0 74.1 27.4 133.0

13258500 596.4 4636.5 5444.7 30.6 29.2 58.2 23.5 33.5

13260000 55.3 4751.8 5035.8 37.9 22.4 42.3 26.4 240.6

13261000 79.5 5313.9 4618.1 36.5 28.2 67.1 26.9 165.2

13266000 1448.3 4141.3 5874.7 22.1 22.2 32.6 19.3 26.1

Region 1

Region 2

Region 3

Region 4

34 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Appendix C. Basin characteristics for selected streamflow-gaging stations--Continued

Gaging 

station 

number A E BR S30 P F BS MCS 

13267000 56.8 4846.2 4800.2 53.4 22.1 55.4 31.6 160.9

13269300 110.8 4901.1 3066.8 17.7 25.1 81.6 18.7 60.1

13270800 38.9 5823.5 3427.4 42.0 28.6 91.6 28.2 220.3

13275500 205.2 5224.6 5393.4 40.8 24.7 74.5 26.5 63.4

13288200 155.7 5742.6 6684.6 63.7 47.5 67.6 40.5 140.3

13289960 177.1 5037.5 6313.8 43.3 27.5 62.2 29.4 107.0

13290190 298.5 4287.7 7681.4 40.0 33.7 50.2 27.4 100.7

13315500 15.1 4742.2 2183.3 45.0 35.4 93.0 27.4 115.0

13316500 576.1 5421.1 7591.0 51.5 29.6 71.8 33.4 57.6

13316800 15.3 5031.2 3191.9 44.2 30.2 69.3 30.6 298.5

13317000 13418.3 6753.8 11152.1 60.3 24.7 58.3 37.7 17.2

13319000 687.4 4582.0 5095.2 21.8 27.6 68.4 20.3 46.0

13320000 104.1 5263.8 5586.1 40.8 39.7 85.9 28.6 164.9

13323600 24.8 5515.7 3278.0 20.8 43.6 77.1 21.3 220.4

13329500 29.6 7461.3 5298.0 87.0 64.6 47.0 57.2 259.5

13330000 71.5 6893.5 5981.8 77.2 56.7 53.1 49.2 196.8

13330500 72.1 5804.7 5859.0 75.0 44.7 67.2 45.6 161.3

13331500 239.2 5699.5 6598.7 70.5 46.5 66.4 43.5 60.8

13337500 260.8 5095.1 3584.2 28.8 35.3 91.7 24.1 36.1

13338000 843.4 5116.5 7070.0 42.4 34.9 91.8 29.7 46.1

13338500 1168.3 4546.6 7553.9 35.1 31.3 70.5 25.7 42.4

13339000 4827.4 4956.2 8163.1 58.6 38.3 77.4 36.2 27.5

13339500 241.4 3528.6 4938.4 25.5 31.5 84.1 22.6 58.2

13340000 5507.9 4736.4 8364.5 54.5 37.4 76.6 34.4 22.1

14010000 61.9 4273.1 3818.7 74.7 46.4 68.3 46.3 157.3

14011000 42.6 3640.0 4263.5 71.2 42.2 57.2 42.1 158.6

12343400 379.3 6361.7 5278.4 55.1 28.4 78.6 33.2 59.8

12346500 88.1 6676.0 4576.0 67.5 29.6 86.4 38.8 208.0

12351000 73.0 6495.2 4390.9 62.0 30.6 79.6 36.5 163.2

13135500 137.5 8204.0 4931.8 67.5 31.4 55.8 40.6 66.8

13136500 92.6 7696.0 4229.0 77.8 35.8 59.7 42.6 63.3

13139500 627.6 7685.6 6615.8 74.0 29.4 43.2 42.7 48.3

13141000 786.2 7347.3 7120.0 69.3 26.5 35.5 40.2 39.5

13185000 831.6 6415.7 7338.2 75.1 32.4 50.2 44.3 57.7

13186000 641.6 7025.2 6088.8 74.4 34.7 50.6 42.1 42.7

13186500 133.6 6276.7 5458.7 47.3 22.4 22.4 29.3 113.8

13187000 55.6 6171.1 5094.1 59.3 32.2 59.2 33.6 166.4

13235000 449.3 6824.5 6785.8 76.6 34.5 54.3 46.7 72.8

13240000 48.7 6921.9 3860.7 67.9 37.2 71.6 42.1 117.4

13292500 93.9 8181.1 3434.5 53.1 34.7 56.9 32.8 59.1

13293000 35.6 8161.5 3578.7 60.4 44.5 47.1 37.6 70.2

13295000 148.9 7318.8 4478.4 37.0 23.9 63.0 26.1 54.8

13295500 510.4 7786.2 4677.4 45.2 29.6 54.9 30.4 36.9

13296000 187.3 7992.1 4200.9 71.1 27.1 74.5 41.0 82.9

13296500 811.1 7791.6 4965.3 53.7 28.0 61.9 33.6 31.5

13308500 133.8 7482.6 3135.5 40.2 28.4 70.8 26.6 89.5

13309000 181.7 7060.3 2987.5 24.7 30.0 70.1 20.2 25.8

13310000 451.5 6981.2 5385.2 74.0 28.7 78.6 44.3 75.5

13310500 91.7 6631.3 3717.0 52.9 37.5 88.7 31.7 99.9

13310700 329.3 6381.8 5387.1 63.8 33.6 83.8 38.0 46.1

13311000 19.3 7724.4 2743.5 62.6 34.0 83.7 35.3 213.0

13311500 42.9 7619.9 3363.9 72.5 30.9 77.3 40.8 178.3

13312000 106.9 7404.6 4182.6 73.0 30.0 78.2 41.7 132.3

13313000 216.4 7135.2 4457.6 40.7 34.3 81.7 28.2 65.6

13314000 1164.0 6696.9 6378.5 60.5 33.2 81.2 37.4 63.7

13315000 12228.0 6913.7 10701.3 60.4 24.4 57.4 37.8 19.9

06013500 277.0 7928.2 4691.8 31.8 18.8 14.5 24.1 78.4

06015500 349.0 6940.1 5193.8 19.6 19.2 28.8 18.8 31.8

06019500 525.5 7235.2 5130.4 20.5 22.9 26.0 20.1 49.9

13108500 228.4 6943.3 3641.5 12.8 26.8 39.4 12.8 36.7

13112000 393.9 6428.8 5062.4 7.5 21.1 22.9 8.6 35.7

13113000 123.2 7027.5 3015.2 23.5 20.3 29.9 19.6 59.3

13113500 238.7 6696.9 3696.0 18.8 19.4 24.4 16.7 52.8

13117300 74.2 8380.5 4280.2 53.7 23.8 54.1 32.7 125.2

13120000 114.7 8659.7 4984.0 72.1 29.8 58.1 43.1 76.3

13120500 440.4 8626.3 5284.1 60.8 27.0 38.0 37.8 42.1

13128900 8.4 9461.0 5123.4 94.2 26.6 21.0 66.2 869.9

13297330 29.5 7618.4 3963.8 85.8 22.6 68.9 47.7 175.6

13297350 6.4 7520.2 3470.0 68.3 21.7 66.3 40.8 403.6

Region 4--Continued

Region 5

Region 6

Appendix C 35
Appendix C. Basin characteristics for selected streamflow-gaging stations--Continued

Gaging 

station 

number A E BR S30 P F BS MCS 

13297355 71.6 7729.2 4114.3 60.2 25.2 73.0 36.3 160.3

13297450 18.3 8951.8 5501.5 64.3 32.0 39.2 41.3 298.9

13298000 540.2 8092.5 6227.5 62.7 26.0 31.7 38.2 58.0

13299000 84.6 7780.8 4996.6 62.0 25.6 62.4 37.2 196.8

13302500 3746.1 7397.5 8655.9 52.9 21.6 37.3 33.4 19.6

13305000 907.1 7430.9 6430.2 36.9 15.6 24.3 25.2 48.6

13305500 1258.0 7108.2 7370.8 39.1 15.3 24.9 26.4 39.8

13306000 210.3 6258.1 6244.4 78.0 22.9 77.8 43.6 100.0

13306500 520.7 7028.2 6652.8 62.2 24.0 80.2 38.6 87.8

13307000 6236.7 7154.3 9419.7 52.8 20.4 41.1 33.3 18.0

10119000 107.1 6070.2 3724.2 17.8 13.2 8.1 17.7 59.0

10172940 28.7 6681.4 2659.9 13.7 17.0 0.7 17.5 187.5

10315500 389.8 6589.8 5032.4 21.8 15.2 2.3 17.5 34.3

10329500 176.2 6210.4 4930.3 26.4 21.9 4.1 21.0 73.6

10352500 225.4 5890.4 3931.3 17.2 17.0 1.4 17.3 60.6

10353000 137.9 6117.4 3436.4 28.0 22.2 2.1 22.2 70.3

10396000 204.7 6197.6 5455.7 15.2 29.1 22.4 16.2 78.3

10406500 86.7 6025.9 3926.9 31.2 16.9 3.9 23.1 147.5

13057940 431.4 6422.9 2544.2 8.4 16.6 19.2 13.3 29.1

13075000 367.4 5587.7 4652.6 20.2 14.3 9.0 16.8 32.6

13083000 52.4 6339.4 3095.6 41.3 17.4 6.2 28.1 116.4

13092000 81.6 6350.2 3685.2 48.7 14.5 9.4 31.6 144.5

13154000 103.3 4812.3 3683.5 14.0 14.0 0.0 15.1 104.0

13155300 14.2 5927.8 2397.6 36.8 23.5 3.0 25.2 203.3

13162500 84.9 7603.0 5683.3 55.2 24.8 24.5 35.3 124.3

13169500 243.7 5170.0 3447.7 7.4 13.8 0.0 10.1 63.9

13170000 103.4 5067.4 3447.5 11.5 14.2 0.1 13.2 114.6

13172680 18.7 6133.6 2569.4 24.9 21.2 38.4 23.0 372.8

13172720 12.5 4883.0 2467.9 21.6 13.6 11.1 21.1 265.9

13172735 13.1 5001.8 2329.3 36.3 14.7 5.5 26.1 322.0

13172740 91.8 5015.7 3719.2 20.7 14.8 12.4 20.2 150.2

13176000 452.3 6660.1 3672.2 24.6 21.6 2.9 20.6 25.2

13178000 454.2 5781.8 3905.0 21.8 26.1 38.9 19.5 30.2

13211309 233.7 2984.4 1178.3 0.0 8.2 0.0 1.7 18.4

13226500 535.3 4133.8 3958.2 15.3 12.3 0.8 17.4 40.2

06037500 434.9 7900.0 2785.6 7.9 42.3 93.9 11.3 30.3

09223000 128.6 8466.6 2454.4 19.5 32.0 72.8 20.4 52.4

10015700 58.5 7971.5 2997.9 1.2 21.6 25.4 9.6 119.9

10040000 45.4 7243.6 2730.5 36.9 23.8 24.8 26.5 56.9

10041000 113.8 7330.7 2826.5 40.7 25.1 36.5 27.4 87.7

10058600 24.3 7684.3 3487.4 40.5 35.1 37.6 27.4 197.2

10077000 50.9 6184.9 1100.5 5.5 18.2 2.3 6.1 24.7

10093000 30.4 7384.3 3983.1 49.4 36.0 53.7 31.3 276.1

10096000 23.2 5691.9 1695.4 18.0 14.2 2.5 19.8 138.9

10099000 16.3 7655.4 4510.9 86.6 40.9 62.2 49.4 413.0

13010065 502.5 8199.4 3509.4 14.7 47.4 82.8 15.8 38.3

13011500 162.7 8134.7 3763.2 20.8 36.3 72.4 20.3 60.6

13011900 330.1 8951.0 4566.8 33.9 37.1 59.7 27.0 58.9

13012000 370.2 8815.8 4619.9 32.8 36.6 60.2 26.3 48.7

13014500 608.0 8863.0 5015.9 26.9 31.6 62.6 23.3 46.4

13019438 82.7 8559.5 4943.0 60.8 31.0 54.5 38.6 129.1

13019500 561.3 7961.5 5650.1 42.6 26.7 60.9 30.3 43.7

13023000 448.8 8105.3 5632.6 54.5 34.9 72.2 35.1 40.0

13024000 48.2 8010.1 4119.5 40.5 32.9 73.4 28.0 106.6

13024500 25.7 8647.5 3738.3 81.3 39.5 73.4 45.1 248.9

13025000 27.7 8496.0 4223.5 84.9 39.3 72.3 49.3 256.8

13027000 20.1 8469.4 3663.7 80.7 40.8 54.0 49.7 243.4

13032000 78.3 7187.5 3806.4 69.7 26.7 56.1 38.8 89.2

13044500 131.1 6675.6 2604.8 5.5 31.8 69.3 9.1 42.7

13045500 123.7 6418.3 2516.2 5.4 35.3 65.4 10.6 93.5

13046680 85.4 7912.5 2270.2 3.3 56.0 87.7 6.9 112.8

13047500 333.6 7540.3 3655.8 7.8 52.9 83.6 11.0 73.7

13049500 512.9 6974.2 4197.5 6.4 42.6 63.3 9.9 50.3

13052200 341.4 7302.9 5223.4 34.5 31.7 39.7 23.6 46.0

13054000 479.2 7200.1 5277.0 30.0 30.3 38.2 21.5 33.6

13055000 874.8 6920.9 6232.1 24.3 27.7 36.1 19.0 28.7

Region 7

Region 8

Region 6--Continued

36 Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Idaho
Hortness, J.E., and Berenbrock, Charles / Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Id