Simulation of Hydraulic Characteristics in the

White Sturgeon Spawning Habitat of the 

Kootenai River near Bonners Ferry, Idaho

Scientific Investigations Report 2005–5110

Prepared in cooperation with the 

Idaho Department of Fish and Game and the

Bonneville Power Administration

U.S. Department of the Interior

U.S. Geological Survey

Simulation of Hydraulic Characteristics in the 

White Sturgeon Spawning Habitat of the 

Kootenai River near Bonners Ferry, Idaho

By Charles Berenbrock

Prepared in cooperation with the Idaho Department of Fish and Game

Scientific Investigations Report 2005–5110

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Berenbrock, Charles, 2005, Simulation of hydraulic characteristics in the white sturgeon spawning habitat of the 

Kootenai River near Bonners Ferry, Idaho: U.S. Geological Survey Scientific Investigations Report 2005-5110, 30 p.
iii

Contents

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

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

Purpose and Scope ................................................................................. 4

Description of Study Reach........................................................................ 6

Previous Investigations ........................................................................... 8

Reach Characteristics.................................................................................... 8

Channel Geometry ................................................................................. 8

Flow Types .......................................................................................... 9

River Stage .......................................................................................... 9

Model Development and Calibration .................................................................. 14

Model Cross Sections .............................................................................. 14

Model Boundaries ................................................................................. 15

Model Calibration ................................................................................. 15

Sensitivity Analyses .............................................................................. 18

Streambed .................................................................................... 18

River Bank .................................................................................... 18

Simulation of Hydraulic Characteristics of the Kootenai River .................................... 19

Location of the Transition Between Backwater and Free-Flowing Water .................. 19

Other Three-Parameter Relations ............................................................... 22

Real-Time Application .................................................................................... 24

Limitations of the Model ................................................................................. 26

Summary ................................................................................................... 27

References Cited.......................................................................................... 28

Glossary ................................................................................................... 29
iv

Figures

Figure 1. Map showing location of the study reach, river miles, and Kootenai River

drainage basin, Idaho, Montana, and British Columbia, Canada ..................... 3

Figure 2. Maps showing locations of stream channel cross sections and river miles on

the Kootenai River, Idaho .................................................................. 4

Figure 3. Diagram showing water-surface curves along a constant, uniform,

mild-sloped channel ........................................................................ 9

Figure 4. Cross sections showing simulated water-surface curves for a discharge of

30,000 cubic feet per second in the entire study reach and in a selected

reach, Kootenai River, Idaho ............................................................... 10

Figure 5. Graph showing daily water levels on Kootenay Lake at Queens Bay

(08NH064), British Columbia, Canada ................................................... 12

Figure 6. Graph showing water-surface elevations at selected gaging stations on the

Kootenai River and Kootenay Lake, 1997–2003 .......................................... 12

Figure 7. Graphs showing relation between water-surface elevation for Queens Bay on

Kootenay Lake and selected gaging stations on the Kootenai River in the

study reach, Idaho........................................................................... 13

Figure 8. Graph showing measured and simulated average velocities at the Tribal

Hatchery gaging station (12310100) (cross section 149.910) relative to

discharge in the study reach and water-surface elevations at Porthill gaging

station, Kootenai River near Bonners Ferry, Idaho .................................... 17

Figure 9. Graph showing simulated location of transition between backwater and

free-flowing water in river miles relative to discharge in the study reach and

water-surface elevations at Porthill gaging station, Kootenai River near

Bonners Ferry, Idaho........................................................................ 21

Figure 10. Graph showing simulated discharge for the Shorty Island side channel

relative to discharge in the study reach and water-surface elevations at

Porthill gaging station, Kootenai River near Bonners Ferry, Idaho .................. 22

Figure 11. Graphs showing simulated average velocity for selected cross sections

relative to discharge in the study reach and water-surface elevations at

Porthill gaging station, Kootenai River near Bonners Ferry, Idaho .................. 23

Figure 12. Graph showing simulated location of transition between backwater and

free-flowing water for a real-time event, October 10, 2004, Kootenai River

near Bonners Ferry, Idaho.................................................................. 25

Figure 13. Map showing location of the simulated transition between backwater and

free-flowing water for a real-time event, October 10, 2004, Kootenai River

near Bonners Ferry, Idaho.................................................................. 26
Tables

Table 1. Elevation of river stage datums at U.S. Geological Survey and Canadian gaging

stations on the Kootenai River and Kootenay Lake, Montana, Idaho, and British

Columbia, Canada ........................................................................... 11

Table 2. Measured and simulated water-surface elevations, Kootenai River, Idaho ......... 16

Table 3. Calibrated Manning’s n values (roughness coefficients) of streambed for four

reaches, Kootenai River, Idaho ............................................................ 16

Table 4. Sensitivity of simulated water-surface elevation to changes in Manning’s n

(roughness coefficient) of streambed for a discharge of 30,200 cubic feet per

second, Kootenai River, Idaho ............................................................ 18

Table 5. Sensitivity of simulated water-surface elevation to changes in Manning’s n

(roughness coefficient) of the river banks for a discharge of 47,500 cubic feet

per second, Kootenai River, Idaho......................................................... 19

Table 6. Simulated normal-depth water-surface elevations at Porthill (cross section

105.603), Kootenai River, Idaho ............................................................ 20

Conversion Factors and Datums

Conversion Factors

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

foot per second (ft/s) 0.3048 meter per second

mile (mi) 1.609 kilometer 

square mile (mi2) 2.590 square kilometer 

Datums

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

(NAVD 88).

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

This page is intentionally left blank.
Abstract 

Hydraulic characterization of the Kootenai River, 

especially in the white sturgeon spawning habitat reach, is 

needed by the Kootenai River White Sturgeon Recovery 

Team to promote hydraulic conditions that improve spawning 

conditions for the white sturgeon (Acipenser transmontanus) 

in the Kootenai River. The decreasing population and 

spawning failure of white sturgeon has led to much concern. 

Few wild juvenile sturgeons are found in the river today. 

Determining the location of the transition between backwater 

and free-flowing water in the Kootenai River is a primary 

focus for biologists who believe that hydraulic changes at 

the transition affect the location where the sturgeon choose 

to spawn. The Kootenai River begins in British Columbia, 

Canada, and flows through Montana, Idaho, and back into 

British Columbia. The 65.6-mile reach of the Kootenai River 

in Idaho was studied. The study area encompasses the white 

sturgeon spawning reach that has been designated as a critical 

habitat.

A one-dimensional hydraulic-flow model of the study 

reach was developed, calibrated, and used to develop relations 

between hydraulic characteristics and water-surface elevation, 

discharge, velocity, and backwater extent. The model used 

164 cross sections, most of which came from a previous river 

survey conducted in 2002–03. The model was calibrated 

to water-surface elevations at specific discharges at five 

gaging stations. Calibrated water-surface elevations ranged 

from about 1,743 to about 1,759 feet, and discharges used 

in calibration ranged from 5,000 to 47,500 cubic feet per 

second. Model calibration was considered acceptable when 

the difference between measured and simulated water-surface 

elevations was ±0.15 foot or less. Measured and simulated 

average velocities also were compared. These comparisons 

indicated agreement between measured and simulated values. 

The location of the transition between backwater and 

free-flowing water was determined using the calibrated model. 

The model was used to simulate hydraulic characteristics for 

a range of water-surface elevations from 1,741 to 1,762 feet 

and discharges from 4,000 to 75,000 cubic feet per second. 

These simulated hydraulic characteristics were used to develop 

a three-parameter relation—discharge in the study reach, 

water-surface elevation at Kootenai River at Porthill gaging 

station (12322000), and the location of the transition between 

backwater and free-flowing water. Simulated hydraulic 

characteristics produced backwater locations ranging from 

river mile (RM) 105.6 (Porthill) to RM 158 (near Crossport), 

a span of about 52 miles. However, backwater locations from 

measured data ranged primarily from RM 152 to RM 157, a 

5-mile span. The average backwater location from measured 

data was at about RM 154. 

Three-parameter relations also were developed for 

determining the amount of discharge in the Shorty Island side 

channel and average velocity at selected cross sections in the 

study reach. Simulated discharge for the side channel relative 

to measured data ranged from 0 to about 5,500 cubic feet per 

second, and simulated average velocity relative to measured 

data ranged from 0 to about 3.5 feet per second. Relations 

using other hydraulic, sediment/incipient motion, ecological, 

and biological characteristics also could be developed. 

The relations also can be used in real time by accessing 

data from the Web. Discharge and stage data for two gaging 

stations, Tribal Hatchery (12310100) and Porthill (12322500), 

are available from the Idaho U.S. Geological Survey web page 

(URL: http://waterdata.usgs.gov/id/nwis/current/?type=flow). 

Because the coordinate axes of the three-parameter relations 

use discharge from the Tribal Hatchery gaging station and 

water-surface elevation from the Porthill gaging station, the 

location of the transition between backwater and free-flowing 

water can be determined for current conditions using the 

real-time data. Similarly, discharge in the Shorty Island side 

channel and (or) average velocity at selected cross sections 

also can be determined for current conditions. 

Simulation of Hydraulic Characteristics in the 

White Sturgeon Spawning Habitat of the 

Kootenai River near Bonners Ferry, Idaho 

By Charles Berenbrock 
Introduction

The Kootenai River is an International river that 

originates in British Columbia and flows through Montana 

and Idaho and then back into British Columbia where it 

joins the Columbia River (fig. 1). The river has undergone 

many physical changes in the last century resulting from the 

drainage of wetlands; construction of dikes along the river’s 

corridor from Bonners Ferry, Idaho, to Kootenay Lake, British 

Columbia; construction of dikes along the river’s corridor 

near Troy and Libby, Montana; construction and operation 

of Libby Dam near Libby, Montana; and elevation control 

of Kootenay Lake by Corra Lynn Dam, British Columbia. 

Streamflow has been significantly altered because of the 

operation of Libby Dam (Barton, 2004), which may negatively 

influence spawning of selected resident fish species. One of 

the resident fish populations, the white sturgeon (Acipenser 

transmontanus), in the river have decreased substantially 

since the construction of Libby Dam in 1972. The Kootenai 

River white sturgeon has been isolated from other sturgeon 

in the Columbia River Basin by natural barriers for more 

than 10,000 years (Northcote, 1973). The last white sturgeon 

spawning event that recruited juveniles in the Kootenai River 

occurred in late spring of 1974. In 1994, the Kootenai River 

white sturgeon was listed as a Federal endangered species, and 

the existing catch and release fishery was closed. Today, few 

wild juvenile sturgeons are found in the river. 

Peak flows in the Kootenai River have substantially 

decreased since the construction and operation of Libby Dam. 

Prior to the dam, natural average peak springtime runoff was 

about 80,000 ft3/s, whereas, post-dam peak runoff during 

the mid- and late-1970s through the early 1990s averaged 

less than 10,000 ft3/s. This decrease is suspected of being 

the major factor in the decrease of successful white sturgeon 

spawning events and, thus, the decreased population of wild 

sturgeon in the Kootenai River. As part of the recovery plan 

for the Kootenai River population of white sturgeon (U.S. 

Fish and Wildlife Service, 1999), spring flows were increased 

beginning in 1994, through managed releases at Libby Dam 

to about 25,000 ft3/s in an attempt to re-create historical peak 

flows and enhance spawning conditions for white sturgeon. 

However, these augmented flows are still substantially less 

than typical pre-dam spring flows.

Post-dam changes of the river system also have altered 

the variability and magnitude of water-surface elevations 

in Kootenay Lake (fig. 1), to which the river discharges 

approximately at river mile (RM) 110, downstream of the 

sturgeon spawning reach. The river is in variable backwater 

from Kootenay Lake to the Bonners Ferry area, resulting 

in low-velocity conditions in the white sturgeon spawning 

habitat. The location of the transition between backwater and 

free-flowing water near Bonners Ferry varies in response 

to changing water-surface elevations in Kootenay Lake and 

water releases from Libby Dam coupled with tributary inflows 

downstream of the dam. Kootenay Lake levels typically are at 

a maximum after spring runoff and at a minimum during the 

autumn and winter months. White sturgeon may be reacting 

to hydraulic conditions caused by the changes in Kootenay 

Lake levels and flows in the river by seeking areas of suitable 

velocities for spawning. Kootenay Lake levels generally are 

lower now than during the pre-Libby Dam period causing the 

location of the transition between backwater and free-flowing 

water to extend not as far upstream; and sturgeon may be 

finding the proper velocities over inferior spawning habitat. 

Ensuring the long-term future of the Kootenai River 

white sturgeon is of concern and contention among biologists, 

ecologists, water managers, engineers, and other interested 

segments of the population. This concern has spurred a 

greater interest in finding ways to promote recruitment of 

the sturgeon. In 1997, the Kootenai River White Sturgeon 

Recovery Team (KRWSRT) was formed under the provision 

of the Endangered Species Act of 1974 to develop and 

implement a recovery plan (Duke and others, 1999). KRWSRT 

is comprised of International multi-government agencies, 

universities, and consultants. Projects initiated by KRWSRT 

will provide information to answer complex recovery and 

management questions and produce tools necessary to 

implement and manage the water resources in the Kootenai 

River. 

The U.S. Geological Survey (USGS) in cooperation with 

the Idaho Department of Fish and Game, a KRWSRT member, 

developed a hydraulic-flow model to improve understanding 

of hydraulic characteristics and to predict the location of 

the transition between backwater and free-flowing water 

(backwater extent) in the white sturgeon spawning reach. 

A one-dimensional hydraulic-flow model of the river 

incorporating the white sturgeon spawning habitat was 

developed. This hydraulic-flow model encompasses the reach 

(65.6 mi) from Leonia to Porthill, Idaho. 

In support of this model and others, about 400 

bathymetric cross sections and longitudinal profiles from 

Libby Dam, Montana, to Kootenay Lake, British Columbia, 

Canada, were measured in 2002–03 (Moran and Berenbrock, 

2003; Barton and others, 2004). Spacing between the cross 

sections ranged from 100 ft in the valley flat near Deep Creek 

and Shorty Island to as much as 1 mi in other areas.

Insights gained from numerical models are critical to the 

assessment and evaluation of possible remedies to improve 

spawning success. Relations from the hydraulic model can 

be incorporated into biological and ecological models of the 

Kootenai River to evaluate and assess the effects of hydraulic 

characteristics on white sturgeon spawning.

 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Figure 1. Location of the study reach, river miles, and Kootenai River drainage basin, Idaho, Montana, and British Columbia, Canada. 

Introduction 

kootHydraulic_fig01

Creek Lake

Kootenay

River

Moyie River

River

Yaak

River

Kootenai

River

Kootenay

Lake

Koocanusa

River Mary St.

Fisher

West

Arm

Kootenay

Lake

Columbia

River

Columbia

Lake

River

Tobacco

Slocan

Lake

River

Slocan

River

Libby

Dam

Lake

Creek

Dam

Kootenai

Falls

Dam

Moyie

Dam

Corra

Lynn

Dam

Bonners

Ferry

Shorty

 Island

Troy

Libby

Creston

Porthill

Nelson

Castlegar

Crossport

Moyie Springs

Queens

Bay

Proctor

Bonnington Falls

Grohman

Narrows

Copeland

Kimberley

Cranbrook

00 40 20 60 KILOMETERS

20 40 MILES

Base from U.S. Geological Surveydigital data, 1:100,000, 1980Albers Equal-Area projectionStandard parallels 43° 30', 47° 30',and -114° 00', 41° 45'No false easting or false northing

117° 116° 115°

118°

49°

50°

BRITISH

COLUMBIA

IDAHO

MONTANA

CANADA

UNITED STATES

PURCELL MOUNTAINS

SELKIRK

MOUNTAINS

CABINET

MOUNTAINS

R O C K Y

M O U N T A I N S

S A L I S H

M O U N T A I N S

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

Mile 80 

Mile100

Mile90

Mile140

Mile120

Mile130

Mile110

Mile180

Mile160

Mile170

Mile150

Mile

190

Mile200

Mile220

Mile 210

08NH064

08NH067 or

12322500

12301933

12305000

EXPLANATION

STUDY REACHRIVER MILEGAGING STATION AND NO.

Mile160

08NH064

+

CANADA

UNITED STATES

Kootenai River

Drainage Basin
Purpose and Scope 

The purpose of this report is to document a model of 

the hydraulic characteristics of the white sturgeon spawning 

habitat of the Kootenai River near Bonners Ferry, Idaho. 

Specifically, determining the location of the transition 

between backwater and free-flowing water is of primary 

interest because biologists believe that the sturgeon sense 

the decreased velocities in backwater areas and will relocate 

to areas with preferred velocities to spawn (Paragamian and 

Kruse, 2001; Paragamian and others, 2001). Stage-discharge 

relations simulated by the model are described by relating 

three parameters—discharge, water-surface elevation (stage 

plus datum, see glossary), and location of transition between 

backwater and free-flowing water in the study reach. The 

study reach (figs. 1 and 2) is the Kootenai River from Leonia 

downstream to Porthill, Idaho, with the primary focus in the 

white sturgeon spawning reach near Bonners Ferry (fig. 2B). 

Mile 160 + 

Mile 170

Mile 172

+ 

+ 

12305000

Kootenai 

River

Moyie

River

IDAHO 

Moyie

Dam

Crossport

Moyie

Springs

Curley 

Creek 

MONTANA 

156.604

156.861

157.561

157.604

157.908

158.847

159.505

159.987

160.438

160.940

162.191

161.590

161.253 162.718

163.027

164.094

164.988

166.811

166.069

167.073

167.516

168.043

168.601

169.109

169.728

170.315

170.794

171.394

171.553

171.875

116° 10' 116° 05'

 48°

45'

 48°

45'

116° 15'

EXPLANATION 

164.094

12305000 GAGING STATION AND NO. 

RIVER MILE

CROSS SECTION AND NO.

A. River miles 156 to 172 

Mile 160 + 

0 1 2 3

0

4 MILES 

1 2 3 4 KILOMETERS 

Figure 2. Locations of stream channel cross sections and river miles on the Kootenai River, Idaho. 

 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
+ 

+ 

Mile 139.8

Mile 140

+ Mile 150

+ 

Mile 153.3

12314000

12310100

12309500

Kootenai 

River 

IDAHO 

Bonners

Ferry

Deep

Creek 

Myrtle

Creek 

Shorty

Island

139.469

139.980

141.014

140.742

141.180

141.677

141.362

140.282

140.141

140.402

142.345

142.177

141.994

142.432 142.575

142.788

143.003

143.179

143.679

143.492

143.406

143.839

143.990

144.319

144.618

144.979

145.272

145.460

145.561

145.600

146.004

145.662 146.359

147.219

146.628

147.342

148.306

148.000

147.678

148.868

148.559

149.910

149.348 148.723

149.008

149.138

149.527

150.289

150.679

151.047

151.438

151.686

151.785

151.873

152.019

152.392

152.628

152.693 152.842

152.879

152.963

152.790

153.033

153.205

153.341

153.468 153.781

154.972

155.559

155.855

155.165

116° 25' 116° 20'

48°

45'

48°

40'

B. River miles 139 to 156 

EXPLANATION 

GAGING STATION AND NO.

RIVER MILE

CROSS SECTION AND NO.

WHITE STURGEON SPAWNING 

 REACH—River mile 139.8 to 153.3

12314000

149.138

Mile 150 + 

0 1 2 3

0

MILES

1 2 3 4 KILOMETERS 

Figure 2.—Continued

 The scope of this report includes (1) definition of 

channel geometry, flow types, and river stages in the study 

reach; (2) development and calibration of a one-dimensional 

hydraulic-flow model of the study reach using the U.S. 

Army Corps of Engineers HEC-RAS model (Brunner, 

2002a, 2002b); and (3) use of the one-dimensional model to 

determine the location of transition between backwater and 

free-flowing water in the white sturgeon spawning reach. 

Modeling included the simulation of a range of river stages at 

the Kootenai River at the Porthill gaging station (12322000) 

and discharge in the study reach. Simulated water-surface 

elevation at Porthill ranged from 1,741 to 1,762 ft, and 

simulated discharge in the study reach ranged from 4,000 to 

75,000 ft3/s. 

Introduction 
koothydraulic_fig2C

Mile 105.6

Mile 120

Mile 110

+ 

+ 

+ Mile 130

+ 

12322000 12321500

12318500

Kootenai 

River 

IDAHO 

Copeland

Parker

Creek

Canyon

Creek

Smith

Creek

Porthill

Trout

Creek

Mission

Creek

UNITED STATES 

Copeland Bridge 

105.878

106.007

105.630

107.658

109.041

110.516

114.332 113.405

111.028

117.427

116.484

115.568

122.018

120.472

119.544

118.704

123.222

123.523

125.004

128.067

126.214

131.471

130.000

129.065

132.454

134.564

137.982

137.070

135.982

138.974

116° 30' 116° 25' 116° 20'

48°

55'

48°

50'

49° 116° 35'

GAGING STATION AND NO.

RIVER MILE

CROSS SECTION AND NO.

12322000

123.222

EXPLANATION 

Mile 120 +

0 1 2 3

0

4 MILES 

1 2 3 4 KILOMETERS 

 C. River miles 105.5 to 139 

Figure 2.—Continued

Description of Study Reach 

The Kootenai River originates in the Rocky Mountains in 

British Columbia, Canada, and flows southward into manmade Lake Koocanusa in British Columbia and Montana 

(fig. 1). The river below Libby Dam flows westward through 

Montana and part of Idaho until it is joined by Deep Creek 

near Bonners Ferry, Idaho. The river then flows north from 

Deep Creek to Kootenay Lake in British Columbia (figs. 1

and 2). The river flows westward from the outlet on the west 

side of Kootenay Lake and joins the Columbia River near 

Castlegar, Canada. The Kootenai River is referred to as the 

Kootenay River in British Columbia. For the purpose of 

this report and as a matter of convenience, the United States 

spelling “Kootenai” will be used when referring to the river 

and the Canadian spelling “Kootenay” will be used when 

referring to the lake because the lake is located entirely within 

British Columbia, Canada. 

 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
The Kootenai River is 448 mi long and drains an area 

of 17,600 mi2. The elevation of the river at its headwaters in 

British Columbia is about 11,900 ft, and at the confluence with 

Kootenay Lake, the elevation is about 1,745 ft. River length 

from Libby Dam, the outlet of Lake Koocanusa, to Kootenay 

Lake is about 145 mi. 

 The study reach of the Kootenai River is a 65.6-mi reach 

starting at Leonia, Idaho (RM 172; fig. 2A), and ending at the 

International Border near Porthill, Idaho (RM 105.6) (fig. 2C). 

This reach encompasses the white sturgeon spawning reach 

(RM 139.8 to RM 153.3), and includes an approximately 

1-mi-long channel around the western side of Shorty Island. 

The side channel is much shallower and narrower than the 

main river channel on the eastern side of the island. Much of 

the study reach is in backwater because water in Kootenay 

Lake backs upstream into the Kootenai River to the reach near 

Bonners Ferry. Backwater conditions occur continuously at 

the confluence of Deep Creek and the Kootenai River (RM 

149.2) (Barton, 2003). In spring and early summer (periods 

of high flow), free-flowing water may extend several miles 

downstream of the U.S. Highway 95 Bridge (RM 152.8). The 

transition between backwater and free-flowing water migrates 

upstream or downstream near Bonners Ferry in response to 

changes in discharge in the river and changes in Kootenay 

Lake elevations. Backwater conditions usually extend 1 to 2 

mi upstream of Bonners Ferry. The extent of backwater has 

been up to the vicinity of Crossport, about 4 mi upstream 

of Bonners Ferry (figs. 1 and 2). The levels in Kootenay 

Lake generally are at a minimum in autumn and winter 

and maximum in late spring and early summer because of 

snowmelt runoff. 

Three geomorphic reaches were identified in the study 

reach—a canyon reach, a braided reach, and a meander reach 

(Synder and Minshall, 1996). The canyon reach extends 

from Libby Dam (RM 220) to Crossport (RM 159.5) (figs. 1

and 2) where the valley begins to widen. The braided reach 

extends from RM 159.5 to a bedrock constriction near the 

U.S. Highway 95 Bridge (RM 152.8) at Bonners Ferry. 

The meander reach extends downstream of the bedrock 

constriction at Bonners Ferry to Kootenay Lake (about 

RM 77). 

The canyon reach consists of a long, straight single 

channel with steep canyon walls and is incised into bedrock. 

Water depths are usually 20 ft, and water-surface slope is 

about 3 × 10-4 ft/ft. White sturgeon spawning has not been 

detected in the canyon reach. 

The braided reach usually consists of multiple channels, 

and the streambed is composed primarily of gravels and 

cobbles. Water depths usually are less than 7 ft, and watersurface slope is about 4.6 × 10-4 ft/ft. White sturgeon 

spawning has not been detected in the braided reach 

(Paragamian and others, 2002). 

The meander reach is a single channel with gentle bends. 

From U.S. Highway 95 Bridge to Ambush Rock (RM 151.9) 

(fig. 2B), the streambed consists primarily of gravel and 

cobbles with some sand; and downstream of Ambush Rock, 

the streambed consists primarily of sand. Water depths in the 

meander reach usually exceed 40 ft, and the water-surface 

slope is about 2 × 10-5 ft/ft, less than one-twentieth or 20 

times less than the slope in the braided reach. Sand dunes 

occur throughout the meander reach including reaches used 

by the sturgeon for spawning (Barton, 2004). Sturgeon mostly 

spawn in the meander reach between RM 141.6 and RM 

149.0 (Paragamian and others, 2001 and 2002; Paragamian 

and Kruse, 2001). In 2001, sturgeon spawned below the U.S. 

Highway 95 bridge. 

 The model was calibrated using stage or flow 

information from five USGS gaging stations located in the 

study reach (fig. 2). Four gaging stations, Kootenai River 

at Leonia (12305000), Kootenai River at Bonners Ferry 

(12309500), Kootenai River at Klockmann Ranch near 

Bonners Ferry (12314000), and Kootenai River at Porthill 

(12322000) have been in operation since the late 1920s. Two 

of the gaging stations (Bonners Ferry and Klockmann Ranch) 

only have stage data because of backwater conditions at the 

sites. Discharge is not a function of stage alone in backwater 

conditions. The Porthill gaging station also is in backwater, 

but discharge has been calculated using two approaches. 

Discharge at the Porthill gaging station has been estimated 

using a one-dimensional hydraulic-flow model (Schaffranek 

and others, 1981) based on water-surface elevation data for 

Porthill and Klockmann Ranch gaging stations and discharge 

data for Boundary Creek near Porthill (12321500; fig. 2C). 

An acoustic Doppler velocity meter (ADVM) was installed at 

the Porthill gaging station in October 2001. Discharge since 

January 2004 has been determined using relations between 

stage and flow area and between velocity from the ADVM 

and average velocity at the gaging station. In September 2002, 

a new gaging station was installed at the Kootenai River at 

Tribal Hatchery near Bonners Ferry (12310100) using an 

ADVM. Discharge at the Tribal Hatchery gaging station also 

is calculated by a velocity-stage-discharge relation using the 

ADVM data. A more complete discussion on the computation 

of discharge at sites using ADVMs is provided in Morlock 

and others (2002). The Leonia gaging station is the only 

station in the study area for which discharge is calculated by a 

stage-discharge relation. 

 From mid/late summer through early/mid spring, flow 

in the river primarily is regulated by Libby Dam, Montana, 

which is about 70 mi upstream of Bonners Ferry, Idaho 

(fig. 1). From mid/late spring through early/mid summer, the 

major contribution of flow to the river is from melting snow 

from tributary areas below Libby Dam.

Introduction 
Previous Investigations 

The first model of the Kootenai River was developed by 

the USGS in 1980 for explicitly determining the amount of 

streamflow entering British Columbia, Canada, from Idaho for 

the International Joint Commission (Schaffranek and others, 

1981, p. 45-49). In backwater reaches such as those in this 

study, discharge is not a function of stage alone, and stagedischarge relations do not work. There may be many stages for 

one discharge or many discharges for one stage. To determine 

discharge entering British Columbia, Canada, a BRANCH 

model (1D unsteady flow) was developed from stage data 

at the Klockmann (12314000) and Porthill gaging stations 

(12322000) (Schaffranek and others, 1981). The model used 

seven cross sections and had the ability to include inflows 

from tributaries. The model was used to calculate flow at 

Porthill until January 2004.

A flood insurance study completed in 1985 modeled 

only the river adjacent to Bonners Ferry (Federal Emergency 

Management Agency, 1985). The model is comprised of 

five cross sections for a total reach length of 5,800 ft. Crosssectional data for the river banks and floodplain were based 

on aerial surveys. The bathymetry was field surveyed in 1983. 

Manning’s roughness coefficients of 0.035 were used for the 

main channel and 0.060 for the river banks and floodplain. 

A one-dimensional unsteady flow model, UNET, was 

developed by the U.S. Army Corps of Engineers (COE) in 

1995 (Patrick McGrane, written commun., 1995). This model 

extends from Bonners Ferry to Queens Bay, British Columbia, 

Canada, and comprises 54 cross sections. Cross sections 

in Idaho were surveyed in 1982, and sections in Canada 

were surveyed in the 1990s. The model was calibrated to 

high-water marks collected in 1974 and to lake elevations in 

Kootenay Lake. The COE developed three-parameter relations 

between Kootenay Lake elevation, discharge at Bonners 

Ferry, and cross-section velocity. A plot of the relation of 

three parameters (average velocity, water-surface elevation 

at Queens Bay gaging station [08NH064], and discharge at 

Bonners Ferry [12309500]) was developed for every cross 

section in Idaho. 

 In 2003, a HEC-RAS model contained within the white 

sturgeon spawning reach was developed by Tetra Tech, Inc., 

and Perkins Geosciences (2004) for COE. The model used 

preliminary cross sections surveyed in 2002 by the USGS 

(Barton and others, 2004). About 50 cross sections were 

used and were adjusted to National Geodetic Vertical Datum 

of 1929 (NGVD 29) from North American Vertical Datum 

of 1988 (NAVD 88) by subtracting 3.64 ft (approximate 

conversion, Tetra Tech, Inc., and Perkins Geosciences, 2004, 

p. 48). They also chose a Manning’s n of 0.035 for the channel 

portion and 0.060 for the river bank portions of the cross 

section because these values were used in the 1985 flood 

insurance study. This model was not calibrated (Tetra Tech, 

Inc., and Perkins Geosciences, 2004). Model results were used 

to determine hydraulic conditions and bed-sediment motions. 

Reach Characteristics

An understanding of flow and hydraulic geometry of the 

Kootenai River is necessary before a hydraulic model of the 

river can be developed. This involves understanding the reach 

characteristics, such as channel geometry, flow, and stage. 

Channel Geometry 

Channel geometry (cross sections and longitudinal 

sections) data of the Kootenai River were collected during 

2002–03 in support of modeling needs. Cross sections (fig. 2) 

from the river survey by Barton and others (2004) were used to 

define channel geometry for the hydraulic-flow model. Cross 

sections used in this study are located between the Leonia 

gaging station (12305000) (RM 171.875) and the Porthill 

gaging station (12322000) (RM 105.603). 

A complete description on the surveying, quality control, 

and processing of these cross sections are given in Barton 

and others (2004). The cross-section data are accessible at 

URL http://id.water.usgs.gov/projects/kootxsections/cross.

htm. A geo-referenced shapefile of these cross sections also 

is available at the above web address. Horizontal control was 

based on North American Datum of 1983 (NAD 83), Idaho 

Transverse Mercator Coordinates, in meters; vertical control 

was based on NAVD 88, in feet. 

 Channel cross sections differ between the canyon, 

braided, and meandering reaches. Cross sections in the canyon 

reach have widths ranging from 400 to 500 ft, and depths 

usually are less than 20 ft. The channel in this reach tends 

to be long and straight. In the braided reach, cross sections 

are about twice as wide as sections in the canyon reach with 

shallower depths (7 ft). These cross sections at low flows have 

exposed islands and (or) bars that divide the river into separate 

channels. At higher flows, the islands and (or) bars are likely 

submerged. However, there are a few permanent islands in this 

reach near RM 154. Cross sections in the meandering reach 

are about 600 ft wide with depths greater than 25 ft through 

depths greater than 50 ft. Cross sections for each of these 

reaches are given in Barton and others (2004, p. 12-14). 

 Eight cross sections on the side channel of Shorty Island 

were generated by using Triangulated Irregular Network 

(TIN) data obtained from many longitudinal surveys and 

several cross section surveys of the reach. The side channel 

was usually too narrow and shallow to obtain adequate cross 

sections using a boat equipped with an echo sounder and 

global positioning system (GPS) equipment (Moran and 

Berenbrock, 2003). Therefore, many longitudinal surveys 

were made in the side channel (Rick Backsen, U.S. Geological 

Survey, oral commun., 2003). These cross sections usually are 

less than 100 ft wide and usually less than 10 ft deep.

 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
-ILDSLOPE

.ORMAL
DEPTHCURVE

-

(ORIZONTALASYMPTOTE

"ACKWATERCURVE

- &REE
FLOWINGCURVE

Figure 3. Water-surface curves along a constant, uniform, mild-sloped channel. 

(Modified from Davidian, 1984, fig. 10, p. 8). 

Flow Types 

The Kootenai River in the study reach, especially in the 

white sturgeon spawning reach, is affected by the elevation 

of Kootenay Lake. The Corra Lynn Dam at the outlet of 

Kootenay Lake causes water to back up (increase in watersurface elevation) into the Kootenai River. Before construction 

of the dam, a natural barrier at Grohman Narrows and 

Bonnington Falls (fig. 1) confined and dammed the water 

behind it into the lake and upstream into the river. 

The spawning reach is usually in backwater and the 

upper parts of the study reach are sometimes in free-flowing 

conditions. Backwater conditions are prevalent in the river 

below the mouth of Deep Creek (RM 149.2). Hypothetical 

water-surface curves have been developed to illustrate 

backwater and free-flowing conditions. Figure 3 represents 

these two flow types. The backwater curve is commonly 

called an M1 curve by hydraulic engineers, and the freeflowing water curve (above critical depth) is called an M2

curve. These curves and others are described by Woodward 

and Posey (1941), Chow (1959), and Henderson (1966). If 

the illustrative reach in figure 3 were elongated upstream, the 

backwater and free-flowing water curves would converge to 

the normal-depth curve. At the point where the backwater 

curve (M1) approaches or converges to the normal-depth 

curve, the effects of backwater cease. The normal-depth curve 

also is known as the no-backwater curve (Davidian, 1984, 

p. 3). Any water-surface curve at or below the normal-depth 

curve is not affected by backwater conditions. Figure 3 also 

illustrates that high downstream water-surface elevations 

cause the convergence point with the normal-depth curve to be 

farther upstream. The influence of backwater conditions on the 

reach is moved upstream and has a longer extent with higher 

downstream water-surface elevations. 

 In natural channels like the Kootenai River, the curves 

are not as smooth as shown in figure 3, because flow depth 

changes from point to point along a channel in response to 

differences in channel shape, slope, and roughness. Figure 4

shows backwater, normal depth, and free-flowing water 

curves for the Kootenai River in the study reach for a model 

simulation of 30,000 ft3/s at six water-surface elevations at 

Porthill gaging station (12322000) (RM 105.603). Two of 

the curves are below the normal-depth curve indicating that 

the reach has free-flowing water for the specified discharge 

and downstream water-surface elevations, and four curves 

are above the normal-depth curve (backwater conditions). 

Figure 4B shows the four backwater curves transitioning from 

backwater conditions to free-flowing conditions between RM 

153 and 157. For example, the curve at a water elevation of 

1,760 ft (fig. 4B) transitions from backwater to free-flowing 

conditions at RM 156.3. 

River Stage 

For this study, water-surface elevation at a gaging 

station was calculated by adding the river stage value to 

the NAVD 88 datum at the gaging station. River stages (or 

water-surface elevations) have been measured on Kootenay 

River and Kootenai Lake for almost a century. Cross sections 

were surveyed during 2002–03 (Barton and others, 2004) and 

stage datums at gaging stations were surveyed using GPS so 

that all data can be converted to one common datum. For this 

study, NAVD 88 was used. Datum elevations in NVGD 29 and 

NAVD 88 at gaging stations in Montana, Idaho, and British 

Columbia, Canada, on the river and lake are shown in table 1. 

Differences between NAVD 88 and NVGD 29 are not the 

same everywhere (table 1) because of the Earth’s irregular 

curvature. 

Reach Characteristics 
Figure 4. Simulated water-surface curves for a discharge of 30,000 cubic feet per second in the entire study reach and in a selected 

reach, Kootenai River, Idaho. 

koothydraulic_fig04

1,820

1,810

1,800

1,790

1,780

1,770

1,760

1,750

1,740

1,730

1,772

1,769

1,766

1,763

1,760

1,757

1,754

110 115 120 125 130 135 140 145 150 155 160 165 170

0 50,000 100,000 150,000 200,000 250,000 300,000 346,561

243,750 248,750 253,750 258,750 263,750 268,750

153 154 155 156 157

WATER-SURFACE ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

RIVER MILES 

DISTANCE, IN FEET UPSTREAM FROM PORTHILL GAGING STATION (12322000) (CROSS SECTION 105.603)

RIVER MILES 

DISTANCE, IN FEET UPSTREAM FROM PORTHILL GAGING STATION (12322000) (CROSS SECTION 105.603)

A. Entire study reach 

B. Selected reach 

Backwater curves 

Free-flowing water curves Normal-depth curve 

Backwater curves 

Free-flowing water curves Normal-depth curve 

WATER-SURFACE ELEVATION, IN FEET

 Normal depth

 1,741

 1,745

 1,750

 1,755

 1,760

 1,762

10 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
The stage of Kootenay Lake has been measured since 

the 1920s (Barton, 2004) at several gaging stations and 

reflect changes made at the lake’s outlet and changes in 

inflow because of Libby Dam. At Queens Bay, stage has 

been measured since the early 1930s (fig. 5). Water-surface 

elevations at Queens Bay show seasonal fluctuations—

maximum during spring and early summer months by 

snowmelt runoff and minimum during autumn and winter 

months (fig. 6). In 1939, the river channel above Corra Lynn 

Dam at Grohman Narrows was deepened and obstructions 

in the channel were removed to increase flow in the river 

and reduce hydraulic losses in the forebay of the dam 

(International Joint Commission, 1938, Order of Approval, 

Kootenay Lake (http://www.ijc.org/conseil_board/kootenay_

lake/en/kootenay_mandate_mandat.htm). This also allows 

the lake to be kept at a lower elevation for dam operation, 

and thus, reduces the backwater effect in the Kootenai River. 

After the deepening of Grohman Narrows and prior to the 

completion of Libby Dam (1940 to 1972), lake elevations 

ranged from 1,766.0 to 1,741.5 ft and averaged 1,749.3 ft 

(fig. 5). During the Libby Dam era from 1973 to 2003, lake 

elevations ranged from 1,758.3 to 1,742.1 ft and averaged 

1,747.7 ft (fig. 5). The most notable difference between these 

two periods is the reduction or the absence of the spring and 

early summer peaks during the Libby Dam era; the maximum 

peak was reduced 7.7 ft. The average lake elevation has been 

lowered 1.6 ft during the Libby Dam era (fig. 5). 

Water-surface elevations for gaging stations on 

Kootenay Lake and Kootenai River through the backwater 

reach have similar patterns (fig. 6) but are at different 

elevations, reflecting the variable water-surface elevations of 

the backwater curve (M1) through the reach. For example, 

when elevations in the lake (Queens Bay on Kootenay Lake) 

increase, water-surface elevations also increase in the river 

(Porthill, Klockmann Ranch, and Bonners Ferry gaging 

stations). 

Stage-stage relations between Queens Bay and each of 

the three river gaging stations (Porthill, Klockmann Ranch, 

and Bonners Ferry) were developed (fig. 7). These curves 

relate the stage in the lake to stage in the river reasonably 

well. The curves and equations were derived using simple 

linear regression methods. These equations relate the watersurface elevation at Queens Bay to water-surface elevations 

at the respective gaging stations. The r value (correlation 

coefficient), k value (number of paired data points), and the 

period of record for the paired data are shown in figure 7. The 

correlation coefficient is a measure of strength of the linear 

relation between two variables (Zar, 1998). An r value of 0 

indicates that there is no linear association between the two 

variables, whereas, an r value of 1 or –1 indicates a strong 

linear association. The correlation coefficient of watersurface elevations for the Queens Bay and Porthill gaging 

stations was 0.95 (strong correlation). The correlation of 

water-surface elevation for the Queens Bay gaging station 

with the other Kootenai River gaging stations (Klockmann 

Ranch and Bonners Ferry) was weaker (r = 0.83 and r = 0.77, 

respectively). The r value decreased as distance increased 

from Kootenay Lake, probably because of the influence of 

inflows from intervening drainages and (or) the effects of 

backwater in the river. 

The simple linear regression curves in figures 7A, 7B, and 

7C fit the data acceptably when water-surface elevations are 

below 1,752.5 ft at Queens Bay, but they should not be used 

when water-surface elevation is above 1,752.5 ft at Queens 

Bay. Above 1,752.5 ft, the data trend in another direction 

from the regression curve. Improvements to these relations 

can be made by using several linear regressions or non-linear 

function(s) that describes the entire dataset more accurately. 

Gaging station 

No. River mile Site Name

Datum elevation (ft) Datum

difference (ft) NGVD 29 NAVD 88

12301933 221.238 Libby Dam 2,100.000 2,103.748 3.748

12305000 171.875 Leonia 1,790.250 1,793.690 3.440

12309500 152.790 Bonners Ferry 1,700.000 1,703.820 3.820

12310100 149.910 Tribal Hatchery – 1,699.880 –

12314000 139.469 Klockmann Ranch 1,700.000 1,703.800 3.800

12322000 105.603 Porthill 1,700.000 1,703.896 3.896

108NH067 or

12322500

274.5 Kuskonook 1,700.000 1,704.052 4.052

108NH064 47.273 Queens Bay 1,700.000 1,704.012 4.012

1 Canadian gaging station identifier.

2 O'Dell and others (2002).

Table 1. Elevation of river stage datums at U.S. Geological Survey and Canadian gaging stations on the Kootenai River and Kootenay Lake, Montana, 

Idaho, and British Columbia, Canada.

[Locations of gaging stations are shown in figures 1 and 2. Datum elevation: NGVD 29, National Geodetic Vertical Datum of 1929; NAVD 88, North American 

Vertical Datum of 1988. Datum difference: NAVD 88 minus NGVD 29. ft, foot; –, no data]

Reach Characteristics 11
koothydraulic_fig05

1,770

1,765

1,760

1,755

1,750

1,745

1,740

1930 1940 1950 1960 1970 1980 1990 2000 2003

LAKE ELEVATION, IN FEET ABOVE

NORTH AMERICAN VERTICAL DATUM OF 1988

YEAR 

Pre-deepening of Grohman Narrows

Post-deepening of Grohman Narrows 

 and pre-Libby Dam—1940–72, 

 average 1,749.3 feet

Post-Libby Dam—1973–2003, average 

 1,747.7 feet

Water level 

Figure 5. Daily water levels on Kootenay Lake at Queens Bay (08NH064), British Columbia, Canada. 

(Data from Environment Canada). (Location of gaging station is shown in figure 1.) 

Figure 6. Water-surface elevations at selected gaging stations on the Kootenai River and Kootenay Lake, 1997–2003.

(Locations of gaging stations are shown in figures 1 and 2.) 

1,770

1,765

1,760

1,755

1,750

1,745

1,740

1997 1998 1999 2000 2001 2002 2003

WATER-SURFACE ELEVATION, IN FEET ABOVE

NORTH AMERICAN VERTICAL DATUM OF 1988

YEAR 

GAGING STATION AND NO. — Break in lines indicates no data

 Queens Bay (08NH064)

 Porthill (12322000)

 Klockmann Ranch (12314000)

 Bonners Ferry (12309500)

12  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Figure 7. Relation between water-surface elevation for Queens Bay on Kootenay Lake and selected gaging stations on the 

Kootenai River in the study reach, Idaho. 

koothydraulic_fig07

1,765

1,760

1,755

1,750

1,745

1,740

1,785

1,780

1,775

1,770

1,765

1,760

1,755

1,750

1,745

1,740 1,745 1,750 1,755 1,760 1,765 1,770

1,780

1,775

1,770

1,765

1,760

1,755

1,750

1,745

1,740

WATER-SURFACE ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

WATER-SURFACE ELEVATION AT QUEENS BAY, IN FEET 

ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

A. Relation between Queens Bay 

 (08NH064) and Porthill (12322000) 

C. Relation between Queens Bay (08NH064) 

 and Bonners Ferry (12309500) 

B. Relation between Queens Bay (08NH064) 

 and Klockmann Ranch (12314000) 

r = 0.95

k = 4,787

Period of paired record:

 November 1989 to October 2003

Porthill = 1.1369 × (Queens Bay) − 237.73

Bonners Ferry = 1.3244 × (Queens Bay) − 561.79 

Klockmann = 1.317 × (Queens Bay) − 550.53

r = 0.77

k = 15,540

Period of paired record:

 October 1960 to October 2003

r = 0.83

k = 13,424

Period of paired record:

 October 1965 to October 2003

1:1

Regression line 

Reach Characteristics 13
Model Development and Calibration

The HEC-RAS computer model, version 3.1 (Brunner, 

2002a and 2002b; and Warner and others, 2002) was used 

to construct a surface-water, hydraulic-flow model of the 

Kootenai River to determine the location of transition between 

backwater and free-flowing water in the study reach. In 

previous modeling studies of this reach and for this present 

study, the streambed was assumed to remain stable during all 

flows, and sediment-transport processes were not simulated. 

The modeled reach extended from the Leonia to the Porthill 

gaging stations—an actual distance of 65.6 mi. 

A difference of 1.4 mi exists between the distance 

calculated using the river-mile (RM) designators (67 mi) and 

the actual distance (65.6 mi) used in the model. The distance 

of 67 mi was based on river mile differences. River miles 

generally are measured in 1-mi increments along the channel 

centerline in an upstream direction beginning with 0 at the 

river mouth, which, in this case, was the outlet to Kootenay 

Lake. River-mile designations were derived by the Columbia 

Basin Inter-Agency Committee (1965) and usually are shown 

on USGS 7.5-minute (1:24,000-scale) maps. Since the 

publication of these documents, the channel length in several 

places along the Kootenai River has changed somewhat 

because of bank erosion, deposition, or channel migration. As 

a result, the actual distances between the river-mile designators 

shown on the maps are not always exactly 1.0 mi. However, 

these designators are used because many people are familiar 

with them and use them for various purposes. However, actual 

distances between cross sections were used in the model. 

HEC-RAS is a computer program that simulates onedimensional, gradually varied, steady flow in open channels 

with fixed boundaries. The model uses the standard step 

method (Chow, 1959, p. 265) to determine changes in 

water-surface elevations from one cross section to the next 

by balancing total energy head at the sections. This onedimensional model assumes that energy is uniform in a cross 

section. This assumption is not accurate in locations where 

flow is not parallel to the main channel or where vertical 

velocities are significant. The model also assumes that flow 

is unobstructed, thus, the channel and floodplain contain no 

debris. 

Model Cross Sections 

A total of 164 cross sections were used in the model: 

131-field-surveyed, 8 Triangulated Irregular Network (TIN) 

generated, 2 bridges, and 23 interpolated. The field-surveyed 

cross sections by Barton and others (2004) were used to define 

channel geometry characteristics for the initial HEC-RAS 

model. Eight TIN-generated cross sections were developed for 

the Shorty Island side channel, and two bridge cross sections 

were generated from bridge design plans. 

Though the HEC-RAS model is capable of simulating 

flow through bridges and (or) culverts, two bridges were not 

incorporated into the model. The ratio of bridge-pier area to 

flow area for the Highway 95 Bridge was less than 5 percent; 

thus, the piers probably do not significantly constrict the 

flow through the bridge. The lowest part of the bridge deck is 

higher than the 500-year flood elevations (Federal Emergency 

Management Agency, 1985) indicating no pressure flow 

will occur through the bridge. These factors were similar for 

the railroad bridge that is about 0.5 mi downstream of the 

Highway 95 Bridge (fig. 2B). 

However, the Copeland Bridge was included in the model 

because parts of the bridge are below the elevation of the river 

banks or levees, and the bridge might cause pressurized flow 

at high stages and (or) discharges. Two cross sections were 

generated from bridge design plans of the Copeland Bridge 

(Lotwick Reese, Idaho Transportation Department, written 

commun., 2004). Because only one cross-section profile was 

given on design plans and considering the narrow width of the 

bridge, the two cross sections were made identical and were 

located immediately upstream and downstream of the bridge 

in the model. 

Twenty-three interpolated cross sections were generated 

at various locations along the reach by interpolating data 

from two adjacent surveyed cross sections to minimize flow 

conveyance changes between the surveyed cross sections, 

thereby maintaining computational stability. For example, 

cross section 152.510 was interpolated from upstream cross 

section 152.628 and downstream cross section 152.392. 

Interpolation was computed by averaging data from the two 

cross sections because cross section 152.510 was centered 

between the upstream and downstream cross sections. This 

interpolation was done using a feature of the HEC-RAS 

model. Interpolated cross sections improve the convergence of 

the solution and the solution of the water surface.

Actual flow distances between cross sections were used 

in the model, not the distance from subtracting cross section 

river-mile designators to compute friction losses. For example, 

the actual flow distance between cross sections 144.618 and 

144.979 is 1,436.5 ft. Based on the river-mile designators, the 

distance is 1,906.1 ft (144.979 mi – 144.618 mi = 0.361 mi × 

5,280 ft/mi = 1,906.1 ft). The resulting difference between the 

two is 469.6 ft (1,906.1 ft – 1,436.5 ft = 469.6 ft). The average 

difference in the study reach between actual flow and rivermile designator distances is about 270 ft. Using actual flow 

distances gives a better estimate of friction losses than using 

the more arbitrary river-mile designator distances. 

14  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
The model requires a roughness coefficient (Manning’s 

n) at every cross section to represent the flow resistance in 

the channel. Factors that affect flow resistance include: (1) 

size, gradation, and angularity of particles comprising the 

streambed; (2) channel shape; (3) type of bed forms (dunes, 

antidunes, and ripples and the presence of bars); (4) riparian 

vegetation; (5) man-made and natural structures (levees and 

bridges); (6) presence of suspended sediment and movement 

of the streambed; and (7) degree of meandering. Resistance 

usually decreases as flow increases because the streambed 

exerts less of an effect on flow as depth increases. Resistance 

also decreases as the size of the bed material decreases. 

Generally, for alluvial channels with coarse materials, 

streambed particle size and gradation probably are more 

important than other factors for determining flow resistance. 

Roughness coefficients established from the previous 

model of the river and floodplain (Federal Emergency 

Management Agency, 1985) were used as the starting values 

for this study. The Federal Emergency Management Agency 

(FEMA) model that was developed for the Bonners Ferry 

Flood Insurance Study assigned a Manning’s n value of 0.035 

to the streambed and 0.060 to the river banks. These values 

were later adjusted during model calibration. Differences in 

n values between the streambed and river banks are attributed 

to differences in surface roughness (size and shape of grains); 

vegetation (density, distribution, and type); geometry (size 

and shape); and obstructions (woody debris, vegetation, 

vehicle bodies, riprap). For example, river banks downstream 

of Crossport generally are quite dense with low to high brush 

and trees although upstream, the river banks are composed 

primarily of large boulders with few trees and brush. Near the 

Kootenai National Wildlife Refuge, large boulders (riprap) 

line the river banks.

Model Boundaries 

Because subcritical flow is the dominant flow condition 

in the study reach, the model requires discharge data at the 

upstream boundary (cross section 171.875), and water-surface 

elevation at the downstream boundary (cross section 105.603). 

Discharge at the upstream boundary (cross section 171.875) 

was based on discharge data from the Leonia gaging station 

(12305000). Discharges from the Moyie River were calculated 

by subtracting flow at the Tribal Hatchery gaging station 

(12310100) from the Leonia gaging station because flows 

from the Moyie River are not gaged near the confluence with 

the Kootenai River. Water-surface elevation at the downstream 

boundary (cross section 105.603) was based on adding stage 

data from the Porthill gaging station (12322000) and the 

NAVD 88 datum.

Model Calibration 

Calibration is the process of adjusting model parameters 

within reasonable limits to obtain the best fit of model results 

to measured data. The process is to repeatedly adjust a 

parameter, run the model, and inspect the difference between 

model results and measured data with the objective of 

minimizing the difference. In this study, calibration consisted 

of comparing the difference between simulated and measured 

water-surface elevations at selected sites and adjusting the 

initial roughness coefficients to minimize the difference. In 

the model, n values were used as a calibration parameter and 

were adjusted between minimum and maximum values for 

the type of channel and flow (Chow, 1959, table 5-6). Model 

calibration was considered acceptable when the difference 

between measured and simulated water-surface elevations for 

each calibration point was within the limit of ±0.15 ft. 

 Calibration at first consisted of comparing simulated 

and measured steady-state water-surface elevations at the 

Klockmann Ranch gaging station (12314000; fig. 2B), Tribal 

Hatchery gaging station (12310100; fig. 2B), Bonners Ferry 

gaging station (12309500; fig. 2B), and the Leonia gaging 

station (12305000; fig. 2A). Nine calibration points in 2002 

and 2003 were identified where discharge and water-surface 

elevation remained steady through the study reach for at 

least several days. Discharge was based on a daily mean 

discharge from the Tribal Hatchery gaging station. Because 

the Tribal Hatchery gaging station was not in operation prior 

to water year 2003, the 47,500 ft3/s discharge was calculated 

by subtracting discharge at the Boundary Creek gaging 

station (12321500, fig. 2C) from the Porthill gaging station 

(12322000; fig. 2C) for the previous day, to account for time 

of travel. Water-surface elevation was based on a daily mean 

stage at the Klockmann Ranch, Tribal Hatchery, and Bonners 

Ferry gaging stations. Water-surface elevations for the Leonia 

gaging station were based on the stage-discharge rating curve. 

Water-surface elevation at a gaging station is derived by 

adding stage to the gaging stations NAVD 88 datum. 

Historical stage and discharge data prior to 2002 were not 

used in the calibration of this model because the current crosssection geometry might not be representative of historical 

conditions. In a comparison of historic (1920 and 1956) 

cross sections to 2002-03 cross sections (Barton and others, 

2004) in the white surgeon spawning reach, Tetra Tech, Inc., 

and Perkins Geosciences (2004) indicated that the average 

streambed change ranged from 1 to 2 ft at most cross sections. 

Changes greater than 3 ft occurred at several cross sections 

and about 5 ft at one cross section. Overall, they indicated that 

a significant amount of deposition occurred in the study reach 

between historic (1920 and 1956) and 2002. At the Copeland 

gaging station (12318500) (RM 123.222), the average 

streambed change of about 5 ft also occurred between 1931 

and 1972 and about 2.5 ft between 1973 and 1993 (Barton, 

2004, fig. 16).

Model Development and Calibration 15
Daily mean 

discharge

(ft3/s)

Date

Water-surface elevation (in feet above North American Vertical Datum of 1988)

Leonia

(12305000) (CS 171.875)

Bonners Ferry

(12309500) (CS 152.790)

Measured Simulated Difference Measured Simulated Difference

5,000 03-10-03 1,804.58 1,804.72 -0.14 – 1,748.44 –

5,200 10-18-03 1,804.69 1,804.79 -.10 1,749.22 1,749.22 0.00

5,540 11-15-02 1,804.88 1,804.89 -.01 1,749.03 1,749.01 .02

10,700 01-02-04 1,807.19 1,807.18 .01 1,751.45 1,751.55 -.10

18,900 08-17-03 1,809.87 1,809.82 .05 1,754.80 1,754.84 -.04

20,900 07-02-03 1,810.43 1,810.47 -.04 1,756.88 1,756.97 -.09

21,200 12-14-03 1,810.51 1,810.50 .01 1,756.21 1,756.30 -.09

30,200 06-13-03 1,812.71 1,812.72 -.01 1,760.94 1,761.03 -.09

47,500 07-03-02 1,816.13 1,816.11 .02 1,765.66 1,765.71 -.05

Daily mean 

discharge

(ft3/s)

Date

Water-surface elevation (in feet above North American Vertical Datum of 1988)

Tribal Hatchery

(12310100) (CS 149.910)

Klockmann Ranch

(12314000) (CS 139.469)

Porthill

(12322000)

(CS 105.603)

Measured Simulated Difference Measured Simulated Difference Measured

5,000 03-10-03 1,745.14 1,745.12 0.02 1,744.44 1,744.44 0.00 1,743.76

5,200 10-18-03 1,748.22 1,748.16 .06 1,747.80 1,747.78 .02 1,747.36

5,540 11-15-02 1,747.45 1,747.42 .03 1,746.93 1,746.91 .02 1,746.40

10,700 01-02-04 1,750.91 1,750.81 .10 1,750.03 1,749.99 .04 1,748.69

18,900 08-17-03 1,754.08 1,753.98 .10 1,752.52 1,752.58 -.06 1,749.58

20,900 07-02-03 1,756.31 1,756.31 .00 1,755.09 1,755.07 .02 1,752.61

21,200 12-14-03 1,755.54 1,755.52 .02 1,754.05 1,754.10 -.05 11,751.19

30,200 06-13-03 1,760.35 1,760.41 -.06 1,758.92 1,758.92 .00 1,755.39

47,500 07-03-02 – 1,765.08 – 1,763.40 1,763.40 .00 1,758.66

1 Water-surface elevation is estimated.

Table 2. Measured and simulated water-surface elevations, Kootenai River, Idaho.

[Locations of gaging stations and cross sections are shown in figure 2. Water-surface elevations for the Leonia gaging station are based on the stage-discharge 

rating curve. CS, cross section; ft, foot; ft3/s, cubic foot per second; –, no data]

Daily mean 

discharge 

(ft3/s)

Calibrated roughness coefficients of streambed for 

reaches between gaging stations

Leonia to 

Bonners Ferry

Bonners Ferry 

to Tribal 

Hatchery

Tribal Hatchery 

to Klockmann 

Ranch

Klockmann 

Ranch to 

Porthill

5,000 0.035 0.040 0.036 0.036

5,200 .035 .040 .036 .036

5,540 .035 .040 .036 .036

10,700 .050 .030 .032 .032

18,900 .044 .030 .030 .030

20,900 .043 .030 .030 .030

21,200 .0425 .030 .030 .030

30,200 .037 .027 .027 .027

47,500 .030 .020 .020 .020

Table 3. Calibrated Manning’s n values (roughness coefficients) of 

streambed for four reaches, Kootenai River, Idaho.

[Locations of reaches are shown in figure 2. ft3/s, cubic feet per second]

Differences in simulated and measured water-surface 

elevation were ±0.10 ft or less except for one value. Results 

from calibration are given in table 2. Manning’s n values 

of the streambed only were adjusted during this process. 

Adjustments were made for the type of flow channel and 

streambed in each reach. Adjustments also were made equally 

to cross sections in each reach. The n values for the river 

banks were not adjusted and remained at 0.060. Table 3 shows 

the final n values for the four reaches. As generally accepted, n

values in all four reaches decrease as discharge increases. 

Simulated and measured velocities were compared 

using a three-parameter relation that can be viewed in a twodimensional chart using lines of equal value to denote the 

third parameter. Figure 8 shows discharge in the study reach 

and water-surface elevation at Porthill gaging station on the 

coordinate axes, and average simulated velocity is denoted 

by a series of curved lines of equal value. The lines of equal 

value in this plot are unique because they represent simulated 

16  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
average velocity distribution at cross section 149.910, and 

more than 150 groups of data triplets (each with three data 

points) were used to develop the plot. 

Measured average velocities for water-surface elevations 

at the Tribal Hatchery gaging station (12310100) plotted 

closely to the lines of equal simulated average velocities 

(fig. 8). The similarity between measured and simulated 

average velocity (fig. 8) indicates that the model closely 

approximates the hydraulic response of the river system. 

Measured average velocities were obtained from discharge 

0.5 

1.0 

2.0 

2.5 

3.0 

3.5 

4.0 

3.75 

1.5 

 EXPLANATION

LINE OF EQUAL SIMULATED AVERAGE 

 VELOCITY—Interval, in feet per second, 

 is variable

MEASURED AVERAGE VELOCITY—Number is average velocity, in feet per second

3.0 

2.20

1.72

1.62

0.77

1.49

1.41

1.23

1.48 1.48

1.48

1.56

1.51

0.69

0.78

0.90

0.97

0.81

0.83

2.20

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741

10,000 20,000 30,000 40,000 50,000 60,000 70,000

WATER-SURFACE ELEVATION AT PORTHILL GAGING STATION,

IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

DISCHARGE IN STUDY REACH, IN CUBIC FEET PER SECOND 

Figure 8. Measured and simulated average velocities at the Tribal Hatchery gaging station (12310100) (cross section 149.910) 

relative to discharge in the study reach and water-surface elevations at Porthill gaging station, Kootenai River near Bonners 

Ferry, Idaho. 

measurements using an acoustic Doppler current profiler 

(ADCP) at the gaging station. At high flows, however, 

discharge can not be measured at the Tribal Hatchery gaging 

station. Measured average velocities at high flows at the 

gaging station were computed by the following procedure: 

(1) transferring the value of discharge at the measurement 

site, (2) determining flow area at the gaging station from the 

average stage during the measurement using the stage-area 

relation at the gaging station, and (3) dividing the measured 

discharge by the flow area. 

Model Development and Calibration 17
Reach

Number 

of cross 

sections in 

each reach

Average difference in watersurface elevation, in feet, when 

Manning's n is changed by

−10 percent +10 percent

Leonia to Bonners 

Ferry

58 –0.79 1.09

Bonners Ferry to Tribal 

Hatchery

16 –.75 .75

Tribal Hatchery to 

Klockmann Ranch1

46 –.65 .65

Klockmann Ranch to 

Porthill

36 –.25 .26

Entire model1 156 –.62 .74

1Excluding the Shorty Island side channel reach.

Table 4. Sensitivity of simulated water-surface elevation to changes 

in Manning’s n (roughness coefficient) of streambed for a discharge of 

30,200 cubic feet per second, Kootenai River, Idaho.

[Locations of reaches are shown in figure 2. Positive value is an increase in 

the simulated water-surface elevation as compared with the calibrated model;

negative value is a decrease in the simulated water-surface elevation as 

compared with the calibrated model. ft3/s, cubic foot per second]

Sensitivity Analyses 

The sensitivity of the model to variations in Manning’s n

of the streambed and the river banks was determined by 

evaluating changes in simulated water-surface elevations as 

n was varied incrementally. The procedure involves holding 

all input parameters constant except the one being analyzed, 

varying that value and observing the results. Exact values 

of change from the sensitivity analysis should be viewed 

cautiously, but relative changes can provide insight as to how a 

particular input parameter may affect the results of the model. 

For all sensitivity simulations, the calibrated cross-section 

geometry was not changed. 

Streambed

To determine the sensitivity of the model to variations 

in Manning’s n of the streambed, a series of simulations 

at a discharge of 30,200 ft3/s were made in which the 

n-value varied by ±10 percent of the initial calibrated 

values. The discharge of 30,200 ft3/s was selected because 

it was near the greatest measured discharge of 32,200 ft3/s 

at the Tribal Hatchery gaging station. For the 10-percentdecrease simulation, for example, n values in the reach from 

Klockmann Ranch to the Tribal Hatchery gaging stations were 

decreased from 0.027 to 0.024. For the 10-percent-increase 

simulation, n values were increased from 0.027 to 0.0297 for 

the Klockmann Ranch to Tribal Hatchery reach. The boundary 

conditions at the upstream and downstream cross sections 

were not changed. 

Results of the sensitivity simulations to changes

 in n-values of the streambed for a discharge of 

30,200 ft3/s (table 4) indicated that the water-surface elevation 

is sensitive to the n value at this discharge. Varying n values 

by ±10 percent of the calibrated values resulted in changes 

in average water-surface elevation from about -0.8 ft to 

about 1.1 ft. Average differences for selected reaches for 

a discharge of 30,200 ft3/s and average differences for the 

entire simulated reach (-0.62 to 0.74 ft) are shown in table 4. 

Average differences were largest at cross sections in the 

canyon-braided reaches. The largest differences of greater than 

1 ft were at upstream cross sections near the Leonia gaging 

station. Average differences in the meander reaches were 

much smaller, and the smallest average differences (-0.25 to 

0.26 ft) were at the reach below Klockmann Ranch gaging 

station (table 4). Differences in reaches upstream of the Tribal 

Hatchery were larger than the calibration limit (±0.15 ft); thus, 

the model is sensitive to changes in n values of the streambed. 

River Bank

Sensitivity of the model to variations in Manning’s n of 

the river bank was evaluated using a discharge of 47,500 ft3/s 

because greater discharges would inundate a greater portion of 

the river banks and therefore affect more of the bank. The river 

bank is the portion of ground that borders the river to the top 

of the bank (start of flood plain). 

Results of the sensitivity simulation to changes in 

n values of the river bank by ±10 percent were near the 

calibration limit of ±0.15 (table 5) and indicated that watersurface elevation was not sensitive to river bank n values. But 

because river bank n values may have greater uncertainty than 

±10 percent, the sensitivity of the model to Manning’s n values 

of the river bank was decreased to -50 percent (0.5 times) and 

increased to +150 percent (1.5 times) of the calibrated values. 

Average differences between simulated and measured 

water-surface elevations were greater than the ±10-percent 

simulations (table 5) when the calibrated n values were 

adjusted to -50 percent and +150 percent. Average differences 

were greater than 1 ft in reaches upstream of the Tribal 

Hatchery. Average differences were smaller (-0.18 to 0.24 ft) 

in the reach below Klockmann Ranch. Average differences 

for the +150-percent simulation were about equivalent to the 

differences in the streambed. Overall, water-surface elevation 

differences were smaller for the river bank simulations than for 

the streambed simulations; thus, river bank differences were 

not as sensitive to changes in Manning’s n as the streambed. 

18  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Simulation of Hydraulic 

Characteristics of the 

Kootenai River

 The model can be used to simulate changes in 

water-surface elevation, velocities, and other hydraulic 

characteristics resulting from changing river discharge and 

stage. For this study, the relations between three dependent 

model variables (three-parameter relations) were developed 

to show the effect of the riverine system. Three-parameter 

relations can be viewed in a two-dimensional chart using a 

series of curved lines to denote the third parameter.

Many model simulations were made to determine the 

response of the river to discharges in the study reach ranging 

from 4,000 to 75,000 ft3/s, and water-surface elevations at 

the Porthill gaging station (12322000) ranging from 1,741 

to 1,762 ft. These limits were selected because the discharge 

spans the range of calibration and recent measured values. The 

upper discharge limit of 75,000 ft3/s was selected because it 

was about 1.5 times the highest calibrated discharge and about 

2 times the greatest measured discharge. Discharge curves 

can be extrapolated two times beyond the greatest measured 

discharge (Rantz, 1982, p. 334). 

Location of the Transition Between 

Backwater and Free-Flowing Water 

Determining the location of the transition between 

backwater and free-flowing water (backwater extent) for 

various discharges in the study reach and water-surface 

elevations at Porthill gaging station was the primary objective 

of this study. Backwater extent can be easily determined 

for steady, uniform, mild-sloped channels, as illustrated 

in figure 3; in riverine systems where changes in channel 

geometry and slope occur, the use of computer models is 

needed to determine backwater extent.

The model was used to simulate backwater, free-flowing 

water, and normal-depth conditions in the Kootenai River. 

Then model simulations were compared, and the location 

of the transition between backwater and free-flowing water 

was determined by locating where water-surface elevations 

from the simulated backwater curve intersected the simulated 

normal-depth curve for each discharge and water-surface 

elevation. 

The calibrated model was used without any modifications 

except for discharge in the study reach and water-surface 

elevation at the downstream boundary (Porthill) to simulate 

backwater and free-flowing water conditions in the study 

reach. 

For normal-depth conditions, however, the calibrated 

model was extended according to the technique by Davidian 

(1984, p. 7) for discharges on very small slopes. The calibrated 

model for the Kootenai River was extended because streambed 

slopes are very small downstream of Bonners Ferry, Idaho. 

The model was extended to cross section 78.746 in British 

Columbia, Canada, about 27 mi downstream of Porthill, 

Idaho. Cross sections from Barton and others (2004) were 

used for this extension. The model was stopped at cross 

section 78.746 because this cross section is similar in width 

to upstream sections, whereas, the next downstream cross 

section (77.251) is several times wider and 30 ft shallower. 

However, this extension did not produce satisfactory results in 

the study reach, so the model was artificially extended farther 

downstream. Davidian (1984, p. 7) indicated that an artificially 

extended reach of 2,000 mi may be required to produce 

satisfactory results. 

To create an artificially extended reach, Davidian (1984, 

p. 7) first indicated that the average streambed slope in the 

artificially extended reach be estimated from the thalwegs 

of the neighboring upstream cross sections. To facilitate this 

calculation, a locally weighted least-squares regression routine 

(LOWESS) was used to produce a smooth profile of thalwegs 

through the irregularly spaced cross sections. Thalwegs from 

Reach

Number of 

cross sections 

in each reach

Average difference in water-surface elevation, in feet,

 when Manning's n is changed by

−10 percent +10 percent –50 percent +150 percent

Leonia to Bonners Ferry 58 –0.16 0.18 –0.71 1.00

Bonners Ferry to Tribal Hatchery 16 –.21 .23 –.93 1.25

Tribal Hatchery to Klockmann Ranch1 46 –.16 .17 –.69 .92

Klockmann Ranch to Porthill 36 –.04 .04 –.18 .24

Entire model1 156 –.14 .15 –.60 .82

1Excluding the Shorty Island side channel reach.

Table 5. Sensitivity of simulated water-surface elevation to changes in Manning’s n (roughness coefficient) of the river banks for a discharge of 

47,500 cubic feet per second, Kootenai River, Idaho.

[Locations of reaches are shown in figure 2. Positive value is an increase in the simulated water-surface elevation as compared with the calibrated model; 

negative value is a decrease in the simulated water-surface elevation as compared with the calibrated model. ft3/s, cubic foot per second]

Simulation of Hydraulic Characteristics of the Kootenai River 19
all cross sections in the model were used in the LOWESSsmoothing routine. Results from the LOWESS-smoothing of 

thalwegs estimated a streambed slope of 6.218×10-5 ft/ft in the 

artificially extended reach; thus, this value was used. 

Secondly, Davidian (1984, p. 7) indicated that crosssection shape in the artificially extended reach be estimated 

from averaging the neighboring upstream cross sections. Only 

the cross-sectional shape from cross section 80.675 (Barton 

and others, 2004, fig. 3G) was used in the artificially extended 

reach because graphical averaging of cross sections is time 

consuming and computer software is not available to perform 

this task. Cross section 80.675 also was similar in crosssectional shape to upstream sections, whereas, downstream 

cross sections 78.746 and 77.251 (Barton and others, 2004, 

fig. 3G) were not similar.

Lastly, Davidian (1984) indicated that enough cross 

sections should be spaced in the artificially extended reach 

to spatially define water-surface elevations in the reach. 

Cross sections were located every 10 mi in the artificial 

extended reach, and provided adequate placement for model 

calculations. Manning’s n values (roughness coefficients) 

from cross section 80.675 were used throughout the artificially 

extended reach. 

An artificially extended reach of 200 mi downstream 

from cross section 78.746 was constructed but did not produce 

satisfactory results. A satisfactory result for the artificially 

extended reach is the convergence of two free-flowing (M2) 

curves in the study reach that have a starting water-surface 

elevation of 1 ft or less apart from one another (Davidian, 

1984). The model was then extended farther downstream and 

the results evaluated until satisfactory results were produced.

The artificial reach had to be extended 600 mi 

downstream from cross section 78.746 or 627 mi downstream 

from Porthill, Idaho, in order to produce satisfactory results. 

This artificially extended model was used to determine the 

normal-depth water-surface elevations at Porthill (cross section 

105.603) given in table 6. These elevations in turn were used 

as starting water-surface elevations (Porthill) for simulating 

normal-depth conditions in the original calibrated model. 

In the extended and artificially extended models, starting 

water-surface elevations at the downstream-most cross section 

were estimated from a slope-conveyance computation of 

normal depth using Manning’s equation for open-channel 

flow. Water-surface elevations for these simulations are 

determined by channel shape and roughness coefficients, and 

thus, channel slope can be used to approximate the energy 

slope. A channel slope of 6.218×10-5 ft/ft was used in the 

artificially extended models to attain normal-depth conditions 

for any discharge. 

Davidian (1984, p. 17) also indicated that the intersection 

of backwater curve with the normal-depth curves is acceptable 

when the backwater (M1) depth is 1.03 times the normal 

depth. Multiplying normal depth by 1.03 causes both curves 

to intersect with one another, otherwise, the curves actually 

do not meet but approach or converge toward one another. 

Therefore, the location between backwater and free-flowing 

water was determined to occur at the intersection between the 

backwater curve and 1.03 times normal depth.

Normal-depth simulations were made using the calibrated 

model, using the normal-depth water-surface elevations from 

table 6, and using the same discharges as in the backwater and 

free-flowing water simulations. Simulations of the backwater 

and free-flowing water and normal-depth water-surface 

elevations were compared at the same discharge to determine 

where flow changed from backwater to free-flowing water 

conditions.

These results were used to develop a three-parameter 

relation—discharge in the study reach and water-surface 

elevation at Porthill on the coordinate axes, and location of 

the transition between backwater and free-flowing water by 

a series of curved lines of equal value, as shown in figure 9. 

More than 100 groups of data triplets (each with three data 

points) were used to develop the plot. River mile 105.6 in 

figure 9 is at the International Boundary between Canada 

and United States near Porthill, Idaho and RM 153 is about 

1,000 ft upstream of U.S. Highway 95 Bridge. Various 

combinations of discharge in the study reach and water-surface 

elevation at Porthill were used in the model to determine the 

location of the transition between backwater and free-flowing 

water that ranged from Porthill (RM 105.6) to about RM 158 

at Crossport, a span of about 52 mi. The transition between 

Simulated 

discharge 

(ft3/s)

Simulated normal-depth 

water-surface elevations 

(in ft above NAVD 88)

4,000 1,727.41

5,000 1,728.62

10,000 1,732.91

15,000 1,736.14

20,000 1,738.91

25,000 1,741.51

30,000 1,744.24

35,000 1,746.61

40,000 1,748.85

45,000 1,750.70

50,000 1,753.16

55,000 1,757.10

60,000 1,760.41

65,000 1,762.91

70,000 1,765.26

75,000 1,767.59

Table 6. Simulated normal-depth water-surface elevations 

at Porthill (cross section 105.603), Kootenai River, Idaho.

[NAVD 88, National Vertical Datum of 1988. ft3/s, cubic foot per 

second; ft, foot]

20 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
backwater and free-flowing water stays at about the same 

river mile for a number of simulated discharges from RM 

153 through RM156 (fig. 9). For example, at a water-surface 

elevation of 1,750 ft, the transition stays at about RM 155.9 

for discharges ranging from 13,000 to 30,000 ft3/s. The area 

of transition between RM 141.6 and RM 149 (reach where 

sturgeon mostly spawn) is quite narrow (fig. 9). 

Paired data comprised of discharge in the study reach 

and water-surface elevation at the Porthill gaging station were 

only available for 1989-2003 because no stage data were 

available prior to 1989. Discharge in the study reach for 1989 

through 2002 was calculated by subtracting the discharge at 

the Porthill gaging station from discharge at Boundary Creek 

gaging station. For 2003, discharge for the Tribal Hatchery 

gaging station was used. 

The measured data indicate that the location of the 

transition between backwater and free-flowing water in the 

study reach extended from RM 152 (downstream of Bonners 

Ferry) to RM 157 (near Crossport), a 5-mile span. The average 

backwater location from measured data was at about RM 

154 (several miles upstream of Bonners Ferry). Measured 

data pairs located downstream of RM 150 (fig. 9) probably 

represent conditions where the water-surface elevation and 

(or) discharge were varying quite rapidly in the study reach. 

Measured data pairs located between RM 141.6 and RM 149 

(where sturgeon mostly spawn) also had water-surface 

elevations and (or) discharges that were varying. Figure 9

cannot be used when the water-surface elevation and (or) 

discharge are varying in the study reach. An example of 

the usage of figure 9 (a three-parameter relation) is given in 

section “Real-Time Application.”

Figure 9. Simulated location of transition between backwater and free-flowing water in river miles relative to discharge in the 

study reach and water-surface elevations at Porthill gaging station, Kootenai River near Bonners Ferry, Idaho.

157 

155 

156 

158 

153 

140 

150 152

154 

105.6 

157 

130 155 

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741

10,000 20,000 30,000 40,000 50,000 60,000 70,000

WATER-SURFACE ELEVATION AT PORTHILL GAGING STATION,

IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

DISCHARGE IN STUDY REACH, IN CUBIC FEET PER SECOND 

OUTSIDE OF STUDY REACH

LINE OF EQUAL SIMULATED LOCATION 

 OF TRANSITION BETWEEN BACKWATER 

 AND FREE-FLOWING WATER — Interval,

 in river miles, is variable

MEASURED DATA FOR DISCHARGE

 IN THE STUDY REACH AND WATER-

 SURFACE ELEVATION AT PORTHILL

 GAGING STATION — Data were collected

 from 1989 through 2003

156

Simulation of Hydraulic Characteristics of the Kootenai River  21
Other Three-Parameter Relations 

Three-parameter relations also were developed for 

discharge in the study reach and water-surface elevation at 

Porthill gaging station on the coordinate axes and two other 

variables—simulated discharge through the Shorty Island side 

channel (fig. 10) and simulated average velocity at selected 

cross sections (fig. 11). 

Simulated discharge in the Shorty Island side 

channel ranged from 0 to more than 8,000 ft3/s, depending 

on discharge in the study reach and water-surface 

elevation at Porthill gaging station (fig. 10). The series 

of curved lines of equal value in figure 10 represent 

simulated discharge in the Shorty Island side channel. 

The shaded region in figure 10 is the region of measured 

data shown in figure 9, excluding unsteady data. 

Figure 10. Simulated discharge for the Shorty Island side channel relative to discharge in the study reach and water-surface 

elevations at Porthill gaging station, Kootenai River near Bonners Ferry, Idaho. 

6500 

8000 

7500 

7000 

4500 

6000 

5500 

5000 

2500 

4000 

3500 

3000 

500 

2000 

1500 

1000 

0 

100 

50 

10 

 EXPLANATION 

LINE OF EQUAL SIMULATED DISCHARGE IN THE 

 SHORTY ISLAND SIDE CHANNEL— Interval, in cubic feet

 per second, is variable 

500 

REGION OF MEASURED DATA 

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741

10,000 20,000 30,000 40,000 50,000 60,000 70,000

WATER-SURFACE ELEVATION AT PORTHILL GAGING STATION,

IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

DISCHARGE IN STUDY REACH, IN CUBIC FEET PER SECOND 

22  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
koothydraulic_fig11

3.75 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

3.5 

3.0 

2.5 

4.5 

2.0 

4.0 

1.5 

1.0 

0.5 

3.5 

3.0 

2.5 

2.0 

4.0 

1.5 

1.0 

0.5 

3.5 

3.0 

2.5 

4.5 

2.0 

4.0 

1.5 

1.0 

0.5 

 EXPLANATION 

4.0 LINE OF EQUAL SIMULATED AVERAGE VELOCITY— Interval, in feet per second, is variable 

REGION OF MEASURED DATA 

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741

10,000 20,000 30,000 40,000 50,000 60,000 70,000

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741 10,000 20,000 30,000 40,000 50,000 60,000 70,000

WATER-SURFACE ELEVATION AT PORTHILL GAGING STATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

DISCHARGE IN STUDY REACH, IN CUBIC FEET PER SECOND 

Cross section 151.047 Cross section 143.003 

Cross section 146.359 Cross section 141.362 

Figure 11. Simulated average velocity for selected cross sections relative to discharge in the study reach and watersurface elevations at Porthill gaging station, Kootenai River near Bonners Ferry, Idaho. 

Simulation of Hydraulic Characteristics of the Kootenai River  23
For the shaded region, simulated discharge for Shorty Island 

ranged from 0 to about 5,500 ft3/s. The non-shaded regions in 

figure 10 show combinations of discharge in the study reach 

and water-surface elevations at Porthill that were not measured 

during 1989–2003. 

Simulated average velocity at five cross sections ranged 

from about 0.5 to about 4 ft/s depending on discharge in the 

study reach and water-surface elevation at Porthill (figs. 8 and 

11). The series of curved lines in figures 8 and 11 represent 

the simulated average velocity. However, simulated average 

velocity distribution (three-parameter relation) of each of 

the five cross sections is unique. Again, the measured region 

(shaded region in figure 11) is represented on the coordinate 

axes. For the shaded region, simulated average velocity ranged 

from 0 to about 3.5 ft/s. The non-shaded regions in figure 11

shows combinations of discharge in the study reach and watersurface elevations at Porthill that have not been observed 

during 1989–2003, but this does not indicate that these 

conditions are impossible. 

Other hydraulic, sediment/incipient motion, ecological, 

and biological variables also can be displayed in a similar 

method as shown in figures 8 through 11. For example, the 

three-parameter relation in figure 11 can be developed for 

any cross section. These three-parameter relations also can be 

displayed longitudinally. Temperature and sturgeon spawning 

locations can be used in these three-parameter relations. 

Real-Time Application

The following example shows how model results were 

used to predict the location of transition between backwater 

and free-flowing water if the current conditions are known. 

Discharge through the Shorty Island side channel and average 

velocity at selected cross sections also can be predicted. 

Data from two telemetered gaging stations in the study 

reach, Tribal Hatchery (12310100) and Porthill (12322000), 

provide real-time data to use in this process. These gaging 

stations transmit real-time stage data from the gaging station 

and index velocity data from the ADVM by satellite to 

the USGS database in Boise, Idaho. The database checks 

the data and computes discharge using a stage-area 

relation and an index velocity-average velocity relation. 

For more information about the procedure, relations, and 

computation, the reader is directed to Morlock and others 

(2002). Discharge and stage data for these gaging stations are 

accessible from the Idaho USGS Web page, http://idaho.usgs.

gov/. 

 To predict the location of transition between backwater 

and free-flowing water:

1. Go to the list of streamgages at Idaho USGS Web 

page (URL: http://waterdata.usgs.gov/id/nwis/current/

?type=flow) and note the river stage at Kootenai River 

at Porthill gaging station (12322000) and discharge at 

Kootenai River at Tribal Hatchery, near Bonners Ferry 

gaging station (12310100). For example, on October 10, 

2004, at 1221 hours (12:21 pm) Mountain Standard Time, 

the river stage at Porthill (station 12322000) was 44.77 ft, 

and discharge at Tribal Hatchery (station 12310100) was 

6,500 ft3/s. 

2. Add 1,703.89 ft (table 1) to the stage at Porthill (44.77 ft 

+ 1,703.89 ft = 1,748.66 ft) to calculate the water-surface 

elevation at Porthill in NAVD 88 datum. 

3. Plot these values on figure 9 using the coordinate 

axes, and note their intersection as shown in figure 

12. If the intersected point does not land on a line of 

equal river miles as shown in figure 12, the user will 

need to interpolate between the lines of equal river 

miles to estimate the point’s river mile value. For a 

stage of 1,748.66 ft and discharge of 6,500 ft3/s, the 

point intersected between RM 153 and RM 154. By 

interpolating between the lines of equal river miles, the 

location of the point occurs at about RM 153.9. 

4. To visualize its spatial location, plot the interpolated 

river mile value of the point on a map that has river miles 

such as figure 2. The location of RM 153.9, upstream 

of Bonners Ferry, is shown on the aerial photograph in 

figure 13. 

In a similar procedure, the other three-parameter relations 

can be used to estimate discharge in the Shorty Island side 

channel (using figure 10) and average velocity at selected 

cross sections (using figures 8 and 11) for a known water-level 

elevation at Porthill gaging station and discharge at the Tribal 

Hatchery gaging station. 

24  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
koothydraulic_fig12

1,748.66 feet 

6,500 cubic feet 

per second 

153.9 

157 

155 

156 

158 

153 

140 

150

154 

105.6 

157 

130 155 

152

1,762

1,759

1,756

1,753

1,750

1,747

1,744

1,741

10,000 20,000 30,000 40,000 50,000 60,000 70,000

WATER-SURFACE ELEVATION AT PORTHILL GAGING STATION,

IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

DISCHARGE IN STUDY REACH, IN CUBIC FEET PER SECOND 

OUTSIDE OF STUDY REACH

LINE OF EQUAL SIMULATED LOCATION 

 OF TRANSITION BETWEEN BACKWATER 

 AND FREE-FLOWING WATER — Interval, 

 in river miles, is variable 

156

Figure 12. Simulated location of transition between backwater and free-flowing water for a real-time event, October 10, 2004, 

Kootenai River near Bonners Ferry, Idaho. 

Real-Time Application  25
Limitations of the Model

When using the model, it is important to realize the 

limitations of the model. A digital model can be a useful tool 

for predicting various hydraulic characteristics in response to 

changes in the riverine system. However, the accuracy with 

which a model can simulate water-surface elevations, velocity, 

and extent of backwater is directly related to the accuracy and 

adequacy of the input data used to calibrate the model. 

The computer model, HEC-RAS, incorporates many 

simplifying assumptions about the riverine system. Most 

important are the assumptions of one-dimensional, gradually 

varied, and steady flow. These simplifications might allow the 

model to simulate water-surface elevations with discharges 

greater than or less than would be experienced under actual 

conditions in the study area. This model successfully simulates 

water-surface elevations in the Kootenai River for its intended 

purpose, even though it is unable to account for (1) uneven 

velocities in a cross section especially in curved sections at 

bends, (2) uneven water-surface elevations in a cross section, 

(3) scour and fill and sediment transport in a cross section, (4) 

infiltration losses and (or) gains in the channel, and (5) other 

aspects of the actual river discharge in the Kootenai River. 

Considerable uncertainty is associated with how velocity 

and shear stress are distributed throughout the study reach. 

These uncertainties cannot be addressed by a one-dimensional 

model like HEC-RAS. Multiple-dimensional models that 

would compute the discharge and velocity field more precisely 

are needed to refine velocity and shear stress distributions 

of the Kootenai River in the study reach. HEC-RAS was 

considered sufficient to provide reasonable results in meeting 

the objectives of this study. 

Verification of the values of Manning’s n (roughness 

coefficients) throughout the modeled reach is needed, 

especially for a wide range of hydraulic and discharge 

conditions. Manning’s n-verification measurements were 

not available for the study reach. If these measurements 

were available, they would permit refinement of the model, 

especially in the reaches between each of the gaging stations 

or in the spawning reach. 

koothydraulic_fig13

Mile 155

Mile 156

Mile 153

Mile 154

Mile 152

+

+

+

+

+

12309500

153.9

48°

42'

48°

41'

116° 20' 116° 19' 116° 18' 116° 17' 116° 16'

0 0.5

0 0.5

1.0 MILE

1.0 KILOMETER CITY OF BONNERS FERRY

LOCATION OF TRANSITION BETWEEN

BACKWATER AND FREE-FLOWING WATER

GAGING STATION AND NO.

RIVER MILE

12309500

EXPLANATION

Mile 152 +

Figure 13. Location of the simulated transition between backwater and free-flowing water for a real-time event, October 10, 

2004, Kootenai River near Bonners Ferry, Idaho. 

26  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Summary

The Kootenai River originates in British Columbia, 

Canada, and flows southward into Lake Koocanusa in 

British Columbia and Montana. From there, the river flows 

westward through Montana and Idaho until it meets Deep 

Creek near Bonners Ferry, Idaho. Then the river flows in a 

northerly direction from Deep Creek to where it empties into 

Kootenay Lake. From Kootenay Lake, it flows westward to 

its confluence with the Columbia River. The study reach is 

65.6 miles in length starting at the Leonia gaging station and 

ending at the Porthill gaging station. The study reach also 

includes an approximately 1-mile-long side channel around 

the western side of Shorty Island. Streamflow in the river 

has been substantially altered by dams and levees, which 

may negatively influence the spawning of the Kootenai River 

white sturgeon. The population of white sturgeon has been 

decreasing and was listed as an Endangered Species in 1994. 

In the study reach, the Kootenai River is characterized 

by a canyon reach, a braided reach, and a meander reach. 

The canyon reach extends from the Leonia gaging station 

to about Crossport and is characterized by a long straight 

channel, and steep canyon walls. The braided reach has 

many exposed islands and (or) bars that divide the river into 

multiple channels especially at low flows, and the streambed 

is composed primarily of gravels and cobbles. This reach 

extends from near Crossport to the U.S. Highway 95 Bridge 

at Bonners Ferry. The meander reach is a single channel with 

gentle bends. Downstream of Ambush Rock near Bonners 

Ferry, the streambed is composed primarily of sand. Sturgeons 

spawn in the meandering reach primarily between river 

mile (RM) 141.6 and RM 149.0, which is considered an 

inferior spawning habitat because of the sands and low-flow 

velocities. Spawning in this area possibly is linked to the 

sturgeons reacting to hydraulic conditions caused by changes 

in Kootenay Lake levels and flows in the river primarily 

controlled by Libby Dam. 

A one-dimensional hydraulic-flow model of the study 

reach, which includes the white sturgeon spawning reach, 

was developed to aid evaluating the reach’s hydraulic 

characteristics. The model was composed of 164 cross 

sections, most of which came from a previous river 

survey-conducted in 2002–03. The model was calibrated to 

water-surface elevation and discharge data from four gaging 

stations. Model calibration was considered acceptable when 

the difference between simulated and measured water-surface 

elevations was ±0.15 foot or less. Actual differences were 

±0.10 foot or less except for one value. Average measured and 

average simulated velocities were compared at one gaging 

station. This comparison indicated that average simulated 

velocities closely matched average measured velocities. 

The calibrated model was used to determine the location 

of the transition between backwater and free-flowing water. 

Normal-depth and backwater simulations were compared, and 

the location was determined by where water-surface elevations 

intersected one another. Discharge in these simulations ranged 

from 4,000 to 75,000 cubic feet per second (ft3/s), about 

1.5 times the highest calibrated discharge. Water-surface 

elevations at Porthill gaging station ranged from 1,741 

to 1,762 feet. Model results were presented by a threeparameter relation where discharge in the study reach and 

water-surface elevation at the Porthill gaging station appear 

on the coordinate axes, and the location between backwater 

and free-flowing water in river miles is denoted by a series of 

curved lines. Measured data pairs (discharge in study reach 

and water-surface elevation at Porthill gaging station) from 

1989 through 2003 also were shown with the three-parameter 

relations. Most of the time, the location of the transition 

between backwater and free-flowing water for the measured 

data occurred between RM 152 downstream of Bonners Ferry 

and RM 157 (near Crossport). The average location was at 

about RM 154. 

Other three-parameter relations were developed for 

determining discharge in the Shorty Island side channel 

and determining average velocity at selected cross sections. 

For these relations, the coordinate axes were not changed, 

only the third parameter (discharge in the side channel and 

average velocity) was changed. Simulated discharge in the 

side channel ranged from 0 to more than 8,000 ft3/s. Relations 

of simulated average velocity at five cross sections in the 

white sturgeon spawning reach also were developed. These 

relations indicate that simulated average velocity ranged from 

about 0.5 foot per second (ft/s) to about 4.0 ft/s in the cross 

sections. Relations using other hydraulic, sediment/incipient 

motion, ecological and biological characteristics also could be 

developed using a similar procedure. 

These three-parameter relations can be used in real time 

by accessing discharge and stage data from the Idaho USGS 

Web page (URL: http://waterdata.usgs.gov/id/nwis/current/

?type=flow). Stage and stream velocity data from the Tribal 

Hatchery and Porthill gaging stations are transmitted in realtime by satellite to USGS computers to compute discharge. 

The coordinate axes of the three-parameter relations use 

discharge from the Tribal Hatchery gaging station and watersurface elevations from the Porthill gaging station. Therefore, 

the location of the transition between backwater and freeflowing water, discharge in Shorty Island side channel, 

and (or) average velocity at selected cross sections can be 

determined for the current conditions. 

Summary  27
References Cited

Barton, G.J., 2003, Characterization of channel substrate, 

and changes in suspended-sediment transport and channel 

geometry in white sturgeon spawning habitat in the 

Kootenai River near Bonners Ferry, Idaho, following the 

closure of Libby Dam: U.S. Geological Survey WaterResources Investigations Report 03-4324, 102 p.

Barton, G.J., Moran, E.H., and Berenbrock, Charles, 2004, 

Surveying cross sections of the Kootenai River between 

Libby Dam, Montana, and Kootenay Lake, British 

Columbia, Canada: U.S. Geological Survey Open-File 

Report 2004-1045, 35 p. 

Brunner, G.W., 2002a, HEC-RAS, River analysis system 

hydraulic reference manual: U.S. Army Corps of Engineers 

Hydrologic Engineering Center, CPD-69, November 2002, 

Version 3.1, 350 p. 

Brunner, G.W., 2002b, HEC-RAS, River analysis system 

user’s manual: U.S. Army Corps of Engineers Hydrologic 

Engineering Center, CPD-68, November 2002, Version 3.1, 

420 p. 

Chow, V.T., 1959, Open-channel hydraulics: New York, 

McGraw-Hill, 680 p. 

Columbia Basin Inter-Agency Committee, 1965, River 

mile index, Kootenai River United States, Kootenay 

River Canada: Columbia Basin Inter-Agency Committee, 

Hydrology Subcommittee, November, 49 p. 

Davidian, Jacob, 1984, Computation of water-surface profiles 

in open channels: U.S. Geological Survey Techniques of 

Water-Resources Investigations, Book 3, Chapter A15, 48 p. 

Duke, S., Anders, P., Ennis, G., Hallock, R., Hammond, J., 

Ireland, S., Laufle, J., Lauzier, R., Lockhard, L., Marotz, 

G., Paragamian, V.L., and Westerfhol, R., 1999, Recovery 

plan for Kootenai River white sturgeon (Acipenser 

transmontanus): Journal of Applied Ichthyol, v. 15, p. 157-

163. 

Federal Emergency Management Agency, 1985, Flood 

insurance study, City of Bonners Ferry, Idaho: Federal 

Emergency Management Agency Flood Insurance Study, 

City of Bonners Ferry, Idaho, Boundary County, community 

number 160031, August 19, 1985, 15 p. 

Henderson, F.M., 1966, Open channel flow: New York, 

MacMillan Publishing Co., Inc., 522 p. 

International Joint Commission, 1938, Order of Approval, 

Kootenay Lake: URL: http://www.ijc.org/conseil_board/

kootenay_lake/en/kootenay_mandate_mandat.htm. 

Moran, E.H., and Berenbrock, Charles, 2003, GPS—Time 

saver and functional: U.S. Geological Survey Western Water 

Watch, v. 1, no. 1, October, p. 6-7. 

Morlock, S.E., Nguyen, H.T., and Ross, J.H., 2002, Feasibility 

of acoustic Doppler velocity meters for the production of 

discharge records from U.S. Geological Survey streamflowgaging stations: U.S. Geological Survey Water-Resources 

Investigations Report 01-4157, 56 p. 

Northcote, T.G., 1973, Some impacts of man on Kootenay 

Lake and its salmonids: Ann Arbor, Mich., Great Lakes 

Fishery Commission Technical Report no. 25, 25 p. 

O’Dell, I.O., Lehmann, A.K., Campbell, A.M., Beattie, S.E., 

and Brennan, T.S., 2002, Water Resources Data, Idaho, 

Water Year 2001, Volume 2. Upper Columbia River Basin 

and Snake River Basin below King Hill: U.S. Geological 

Survey Water-Data Report ID-01-2, 390 p. 

Paragamian, V.L., and Kruse, G., 2001, Kootenai River white 

sturgeon spawning migration behavior and a predictive 

model: North American Journal of Fisheries Management, 

American Fisheries Society, v. 21, 10-21 p. 

Paragamian, V.L., Kruse, G., and Wakkinen V., 2001, 

Spawning habitat of Kootenai River white sturgeon, 

post-Libby Dam: North American Journal of Fisheries 

Management, American Fisheries Society, v. 21, 22-33 p. 

Paragamian, V.L., Wakkinen, V.D., and Kruse, G., 2002, 

Spawning locations and movement of Kootenai white 

sturgeon: Journal of Applied Ichthyology, v. 18, 608-616 p. 

Rantz, S.E., 1982, Measurement and computation of 

streamflow: Volume 2, Computation of discharge: U.S. 

Geological Survey Water-Supply Paper 2175, p. 285-631. 

Schaffranek, R.W., Baltzer, R.A., and Goldberg, D.E., 1981, A 

model for simulation of flow in singular and interconnected 

channels: U.S. Geological Survey Techniques of WaterResources Investigations, Chap. C3, Book 7, 110 p. 

Snyder, E.B., and Minshall, G.W., 1996, Ecosystem 

metabolism and nutrient dynamics in the Kootenai River 

in relation to impoundment and flow enhancement of 

fisheries management: Stream Ecology Center, Idaho State 

University, variously paged. 

Tetra Tech, Inc., and Perkins Geosciences, 2004, Kootenai 

River geomorphic assessment, Bonners Ferry, Idaho, 

Final Report: Seattle, Wash., Tetra Tech, Inc., and Perkins 

Geosciences, 78 p., 4 apps. 

U.S. Fish and Wildlife Service, 1999, Recovery plan for the 

Kootenai River population of the white sturgeon (Acipenser 

transmontanus): Portland, Oregon, September 30, variously 

paged. 

Warner, J.C., Brunner, G.W., Wolfe, B.C., and Piper, S.S., 

2002, HEC-RAS, River Analysis System Application 

Guide: U.S. Army Corps of Engineers Hydrologic 

Engineering Center, CPD-70, November 2002, Version 3.1, 

344 p. 

Woodward, S.M., and Posey, C.J., 1941, Hydraulics of steady 

flow in open channels: New York, John Wiley, 151 p. 

Zar, J.H., 1998, Biostatistical analysis, 4th ed.: Englewood 

Cliffs, N.J., Prentice-Hall, Inc., 929 p. 

28  Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Glossary

backwater: Water backed up or retarded in its course as 

compared with its normal or free-flowing condition of flow. 

Backwater is an increase in upstream flow depth due to a 

constriction in a channel, change in channel slope, or change 

in roughness. Backwater is denoted by hydraulic engineers as 

an M1 curve. 

channel: The channel includes the thalweg and streambed. 

confluence: The flowing together of two or more streams; 

the place where a tributary joins the main stream. 

conveyance: A measure of the carrying capacity of a 

channel section and is directly proportional to channel 

discharge. Conveyance is that part of Manning’s equation that 

excludes the square root of the energy gradient or friction 

slope. 

cross section: A series of coordinate pairs of elevation and 

stationing that describes the channel shape perpendicular to 

the mean flow direction. 

flood: Any relatively high streamflow that overtops the 

natural or artificial banks of a river. 

floodplain: Land adjoining (or near) the channel of 

a watercourse which has been, or may be, covered by 

floodwaters. A flood plain functions as a temporary channel or 

reservoir for overbank flows. The lowland that borders a river 

and is usually dry but subject to flooding. 

free-flowing water: Water that is not backed up or retarded 

in its course. Free-flowing water is denoted by hydraulic 

engineers as an M2 or M3 curve. 

high-water marks: Evidence of the stage reached by a flow. 

High-water marks generally consist of debris, scour marks, or 

staining of rocks found along the channel banks. 

hydrograph: A graph of stage or discharge versus time. 

LOWESS smoothing: A robust, locally weighted regression 

method to smooth data. A locally weighted polynomial 

regression is fit to each point and nearby points. This 

method also is referred as LOESS smoothing. The smoothed 

data provides a clearer shape of the relation between the 

independent and dependent variables. 

Manning’s roughness coefficient (n values) or Manning’s n: 

A measure of the frictional resistance exerted by a channel 

on the flow. The n value also can reflect other energy losses 

such as those resulting from the transport of material and 

debris, unsteady flow, extreme turbulence, that are difficult or 

impossible to isolate and quantify. 

normal depth: The depth of flow for a given discharge, fixed 

channel shape, slope, and roughness. 

reach: A length of stream that is chosen to represent a uniform 

set of physical, chemical, and biological conditions. 

river bank: The sloping ground that borders a stream 

and confines the water in the channel. It is bordered by the 

floodplain and channel. 

runoff peak flow: The largest value of the runoff flow, which 

occurs during a flood, as measured at a particular point in the 

drainage basin. 

slope: The change in elevation per unit change in the 

channel’s length. 

stage: The height of a water surface above gage datum; 

same as gage height. 

stage-discharge relation: The relation between the watersurface elevation and discharge. 

steady flow: Discharge and depth of flow does not change 

with time or during a selected period of time. 

streamflow, discharge, or flow: A general term for water 

flowing through a channel. 

subcritical flow: If the flow is subcritical, flow depth is 

greater than the flow depth in critical flow. Inertial forces are 

less than the gravitational forces. 

thalweg: A line connecting the lowest points along the 

length of a riverbed. It can be quite sinuous and wander within 

the channel. 

water-surface curves or profile: Longitudinal plots of the 

water-surface elevation as a function of distance downstream 

through a channel reach. 

water-surface elevation: Height of a water surface above 

a datum; same as adding stage and NAVD 88 datum for 

example. 

velocity-stage-discharge relation: Relation between 

velocity, water-surface elevation, and discharge.

Glossary  29
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30 Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat, Kootenai River, Bonners Ferry, Idaho
Manuscript approved for publication, May 31, 2005

Prepared by the Publishing Group, U.S. Geological Survey, 

Washington Water Science Center, Tacoma, Washington

USGS Publishing staff

Chester Zenone

Bill Gibbs 

Linda Rogers

Sharon Wahlstrom

For more information concerning the research in this report, contact the 

Idaho Science Center Director, 

U.S. Geological Survey, 230 Collins Road

Boise, Idaho 83702

http://id.water.usgs.gov
SIR 2005–5110 Berenbrock

Printed on recycled paper

Simulation of Hydraulic Characteristics in the White Sturgeon Spawning Habitat 

of the Kootenai River near Bonners Ferry, Idaho