Prepared in cooperation with the U.S. Army Corps of Engineers

Control-Structure Ratings on the Chicago Sanitary and 

Ship Canal near Lockport, Illinois

Scientific Investigations Report 2012–5131

U.S. Department of the Interior

U.S. Geological Survey
Cover photograph:

Lockport Powerhouse (photo taken looking downstream on July 24, 2010)
Control-Structure Ratings on the Chicago 

Sanitary and Ship Canal near Lockport, 

Illinois

By Timothy D. Straub, Kevin K. Johnson, Jon E. Hortness, and James J. Duncker

Prepared in cooperation with the U.S. Army Corps of Engineers

Scientific Investigations Report 2012–5131

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Suggested citation:

Straub, T.D., Johnson, K.K., Hortness, J.E., and Duncker, J.J., 2012, Control-structure ratings on the Chicago Sanitary and 

Ship Canal near Lockport, Illinois: U.S. Geological Survey Scientific Investigations Report 2012–5131, 25 p.
iii

Acknowledgments

The authors acknowledge Jim Stiman of the U.S. Army Corps of Engineers (USACE) for 

supporting the use of advanced methodologies and providing technical assistance during this 

study. The authors also acknowledge Jim Yurik, Martin Castro, and Phil Nieman of the Metropolitan Water Reclamation District of Greater Chicago (MWRD) for their assistance with the 

coordination of gage installation and gate-opening information, along with overall technical 

support regarding the structures. The authors acknowledge Tzuoh-Ying Su, USACE, and Chad 

Wagner, U.S. Geological Survey (USGS), for their technical assistance and reviews of the 

report. Finally, the authors acknowledge the following USGS colleagues: Jennifer Sharpe, for 

report illustrations development; and Mark Lynch, Ryan Beaulin, Greg Goodwin, John Goossen, and Mike Lee for making the streamflow measurements. 
iv

Contents

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

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

Purpose and Scope .............................................................................................................................1

Streamflow During Study Period .......................................................................................................1

Previous Studies ...................................................................................................................................3

Lockport Controlling Works..........................................................................................................................3

Approach................................................................................................................................................3

Measurement Summary ......................................................................................................................6

Results ....................................................................................................................................................8

Example Calculations.........................................................................................................................15

Lockport Powerhouse.................................................................................................................................15

Approach..............................................................................................................................................17

Measurement Summary ....................................................................................................................17

Results ..................................................................................................................................................17

Potential Future Work .................................................................................................................................24

Controlling Works ...............................................................................................................................24

Powerhouse.........................................................................................................................................24

Summary .......................................................................................................................................................24

References Cited .........................................................................................................................................25

Figures

 1. Map showing location of the Lockport Powerhouse and Controlling Works and 
v

 7. Schematic (side view) of the Controlling Works sluice gates on the Chicago 

1. Statistical summary of streamflow for the U.S. Geological Survey streamflowgaging station on the Des Plaines River at Riverside, Illinois ...............................................3

2. Streamflow measurements during the study period for the U.S. Geological Survey 

streamflow-gaging station at Des Plaines River at Lockport (DPR-L), Illinois ...................6

3. Streamflow measurements during the study period for the U.S. Geological Survey 

streamflow-gaging station at Des Plaines River at Division Street at Lockport 

(DPR-DSL), Illinois.........................................................................................................................6

4. Number of gates open and flow conditions for two storm events when the 

controlling works at Lockport, Illinois, were in operation .....................................................9

5. Flow measurements during the study period for the U.S. Geological Survey streamflow-gaging station at the Chicago Sanitary and Ship Canal at Lockport (CSSC-LPH), 

Illinois, and computed flows from Hart and McGee (1985) and the Metropolitan 

Water Reclamation District.......................................................................................................19
vi

Conversion Factors and Vertical Datum

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2

) 929.0 square centimeter (cm2)

square foot (ft2

) 0.09290 square meter (m2)

square mile (mi2

) 259.0 hectare (ha)

square mile (mi2

) 2.590 square kilometer (km2) 

Velocity

foot per second (ft/s) .3048 meter per second (m/s) 

Flow rate

cubic foot per second (ft3

/s) .02832 cubic meter per second (m3/s)

Vertical coordinate information is referenced to the Chicago City Datum (CCD); 0 ft CCD equals 

579.48 ft National Geodetic Vertical Datum of 1929 (NGVD29).

A water year (WY) is the 12-month period from October 1 through September 30 and is 

designated by the calendar year in which it ends. For example, WY 2010 is from October 1, 2009, 

to September 30, 2010.

Abbreviations

ADCP acoustic Doppler current profiler

CCD Chicago City Datum

CSSC Chicago Sanitary and Ship Canal

CSSC-LCW Chicago Sanitary and Ship Canal Lockport Controlling Works

CSSC-LPH Chicago Sanitary and Ship Canal at Lockport (powerhouse gage)

DPR-L Des Plaines River at Lockport

DPR-DSL Des Plaines River at Division Street at Lockport

FW free weir

LCW Lockport Controlling Works

MWRD Metropolitan Water Reclamation District of Greater Chicago

NWIS National Water Information System

SW submerged weir

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

WSE water-surface elevation

WY water year
Control-Structure Ratings on the Chicago Sanitary and 

Ship Canal near Lockport, Illinois

By Timothy D. Straub, Kevin K. Johnson, Jon E. Hortness, and James J. Duncker

Abstract

The U.S. Army Corps of Engineers and the Metropolitan 

Water Reclamation District of Greater Chicago regulate flows 

through control structures along the Lake Michigan lakefront 

and the Chicago Sanitary and Ship Canal (CSSC) for Lake 

Michigan diversion accounting, flood control, sanitary, and 

navigation purposes. This report documents the measurement 

and computation of flow through the Lockport Controlling 

Works (LCW) and the Lockport Powerhouse. This analysis 

aided in evaluation of the ratings at both structures, and the 

development of new ratings at the controlling works. 

The LCW structure consists of seven 30-feet (ft) wide 

sluice gates and is used to divert water from the CSSC and 

into the Des Plaines River. The flow regimes for the sluice 

gate included both free and submerged weir. Forty and 491 

flow values from U.S. Geological Survey streamflow-gaging 

stations were used to develop equations describing free- and 

submerged-weir flow, respectively, through the sluice gates. 

The equations were developed for canal headwater elevations 

ranging from −7.0 to −10.5 ft Chicago City Datum (CCD), and 

tailwater (Des Plaines River at Lockport) to headwater (CSSCLCW-Base) ratios ranging from 0.31 to 0.66.

The Lockport Powerhouse structure consists of nine 

9-ft wide by 14-ft high sluice gates and two 10-ft diameter 

turbines. Both tailwater and no-tailwater effect flow regimes 

occurred during nine measurements. Also, the canal headwater 

elevations ranged from −2.74 to −8.45 ft CCD, and the gates 

were configured six different ways during the measurements. 

Introduction 

The U.S. Army Corps of Engineers (USACE) and the 

Metropolitan Water Reclamation District of Greater Chicago 

(MWRD) regulate flows through control structures along the 

Lake Michigan lakefront and the Chicago Sanitary and Ship 

Canal (CSSC). New acoustic technologies for measuring 

velocity and flow are being used to determine flow for Lake 

Michigan diversion accounting, flood control, sanitary, and 

navigation purposes. For example, periodic acoustic Doppler 

current profiler (ADCP) measurements are used to determine 

flow and an acoustic side-looker measurement device is 

used to provide continuous velocity data for a velocity-index 

rating at the streamgage near Lemont, Illinois (05536890) 

(fig. 1). These advanced technologies provide an opportunity 

to evaluate the ratings for flow through the control structures 

near Lockport, Illinois (fig. 1). The evaluation and analysis 

were done in 2010 and 2011 by the U.S. Geological Survey 

(USGS), in cooperation with the USACE. 

Purpose and Scope 

This report documents the measurement of flow through 

the Lockport Controlling Works (LCW) (7 sluice gates) and 

the Lockport Powerhouse (9 sluice gates and 2 turbines) utilizing acoustic technology. At both locations, the existing ratings 

were evaluated for as many gates as were open at the time of 

two storm events (May 13, 2010, and July 24–25, 2010). At 

each location, all the gates were not necessarily open during 

the events because of operational procedures, gate malfunctions, or replacement of gates. Flow data from streamflowgaging stations enabled new ratings to be developed for the 

controlling works. 

Flow measurements on the Des Plaines River were 

completed for a wide range of canal stages during two storm 

events when the controlling works gates and (or) powerhouse 

gates were operational during March–November 2010. Three 

of the nine sluice gates at the powerhouse were undergoing 

repairs throughout the measurement time period, while others were not always in operation during measurements. All 

seven controlling works sluice gates were open during the first 

storm, and five gates were open during the second storm.

Streamflow During Study Period 

A statistical summary of streamflow at a long-term USGS 

streamflow-gaging station on the Des Plaines River at Riverside, Illinois (05532500), during the study for water year 

(WY) 2010 is presented in table 1 and compared to statistics 

for the full period of record (WY 1944–2010) at this station. 

The summary shows that both low and high streamflows 

occurred during the data-collection period, including a peak 

streamflow within 15 percent of the peak of record.
2 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

DU PAGE COUNTY

DU PAGE COUNTY

WILL COUNTY

42°15'

41°45'

41°30'

42°

88°15' 87°45' 87°30'

Chicago

Sanitary

and

Ship

Canal

Calumet Sag

Salt

Creek

Little Calumet R.

Cr

Willow

South Branch

Chicago River

North Shore Channel

COOK COUNTY

ILLINOI

S

INDIAN

A

LAKE

MICHIGAN

Area of

enlargement

ILLINOIS

Lockport Powerhouse

Controlling Works 

88°

Des Plaines

River

Branch

North

Chicago

LAKE COUNTY

COOK COUNTY River

Des Plaines

U.S. Geological Survey streamflowgaging station and identifier

Control structure

EXPLANATION

10 MILES

10 KILOMETERS

5

0 5

0

Calumet R.

Grand

Calumet R.

River

Base from U.S. Geological Survey, 1:100,00-scale digital data

Albers Equal-Area Conic Projection

Standard parallels 45° and 33°, central meridian -89°.

05534100

05534050

05532500

05536890

05536890

Figure 1. Location of the Lockport Powerhouse and Controlling Works and overview of drainage into the Chicago 

Sanitary and Ship Canal and Des Plaines River, Illinois.
Lockport Controlling Works 3

Table 1. Statistical summary of streamflow for the U.S. Geological Survey streamflow-gaging station on the Des Plaines River at 

Riverside, Illinois (05532500).

[ft3/s, cubic foot per second]

Water 

year(s)1

Annual

mean

streamflow

(ft3

/s)

Daily mean streamflow Maximum

Highest Lowest peak streamflow

Streamflow

(ft3

/s) Date Streamflow(ft3/s) Date Streamflow(ft3/s) Date

2010 942 6,720 07/25/2010 180 09/30/2010 8,380 07/24/2010

1944–2010 589 9,180 08/15/1987 0 08/23/1962 9,770 08/15/1987

1

A water year (WY) is the 12-month period from October 1 through September 30 and is designated by the calendar year in which it ends. For example, 

WY 2010 is from October 1, 2009, to September 30, 2010.

Previous Studies

The earliest record found of structure ratings near Lockport, Illinois, was a paper copy of a controlling works rating 

table dated 1947 (Phil Nieman, Metropolitan Water Reclamation District of Greater Chicago, written commun., 2010). In 

1961, a University of Illinois Master’s Thesis was completed 

utilizing a physical model to study the flow conditions at the 

Lockport Powerhouse (Muga, 1961). In 1985, the USACE 

analyzed and revised ratings based on theory and previous 

studies for both the powerhouse and controlling works (Hart 

and McGee, 1985).

Lockport Controlling Works

The Lockport Controlling Works (LCW) is located 2.1 mi 

upstream of the Lockport Lock and Powerhouse (fig. 1). The 

drainage area at the headwater gage (CSSC at Lockport Controlling Works (CSSC-LCW), Illinois, 05536998) is 739.5 mi2

. 

The structure is used to divert water from the CSSC into the 

Des Plaines River. The structure consists of seven 30-ft wide 

sluice gates with a sill elevation of −15.0 Chicago City Datum 

(CCD) (figs. 2–7).

Approach

To determine flow through the LCW, two streamgages 

were installed in March 2010 on the Des Plaines River at 

Lockport (DPR-L), Illinois (05534050), and Des Plaines 

River at Division Street at Lockport (DPR-DSL), Illinois 

(05534100). Both gages had continuous stage sensors (collected at 5-minute interval), as well as storm event measurements and routine flow measurements, made as needed for 

rating development and continuous-discharge calculation. 

The DPR-L gage (05534050) was located on the Materials 

Road bridge immediately upstream of where the controlling 

works flow enters the Des Plaines River (figs. 2 and 3). This 

location included an acoustic side-looker measurement device 

which provided velocity data for a velocity-index rating (Ruhl 

and Simpson, 2005; Morlock and others, 2002) because of 

the backwater effect from the controlling-works flow that 

precluded use of a standard stage-discharge rating to obtain 

accurate discharge data.

The DPR-DSL gage was located on the Division Street 

bridge (fig. 2) downstream of where the controlling works 

flow enters the Des Plaines River. The 9th Street bridge was 

considered as a possible location, but rejected because of 

observed turbulent and air-entrained high flow conditions that 

would make ADCP measurements difficult and less accurate. 

A bank-operated cableway was installed to help facilitate 

ADCP measurements at Division Street. The difference in 

flow between the gages DPR-L and DPR-DSL was used as the 

flow through the controlling works. 

Two stage sensors were installed at the CSSC headwater 

gage (05536998) near the controlling works (fig. 3). The base 

gage at CSSC-LCW was on the south side of the controlling works and the auxiliary gage was as far north on the old 

structure as possible to be out of the drawdown, but still not 

in the vicinity of docking barges (sensor located approximately 300 ft upstream of the first gate as shown in fig. 3). 

Most hydraulic formulae to compute discharge are based 

on the head outside of the drawdown zone. Under current 

(2012) MWRD operating conditions, the canal is lowered 

significantly using the powerhouse, and consequently, rapid 

drawdown does not occur at the controlling works. For the 

purposes of this study, only the base gage was used because 

the streambed is exposed at approximately −8.5 ft CCD at the 

auxiliary gage, preventing data collection within the operating 

conditions of the canal.

Data from MWRD headwater and tailwater gages (fig. 3) 

were not recoverable for the study period and could not be 

used to compute submergence ratios. Submergence ratios were 

instead calculated using data from CSSC-LCW and DPR-L. 

The submergence ratios are needed to determine which rating 

equation should be used. The structure rating development 

used a range of canal stages, along with standard control-structure rating techniques (Chow, 1959; Collins, 1977; Roberson 

and others, 1998). 
4 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

¬«53

¬«171

¬«7

88 5’ 88 4’30" 88 4’ 88 3’30"

41 36’

41 35’30"

41 35’

41 34’30"

Lockport Powerhouse

(2 turbine/gates, 9 sluice gates, lock)

Controlling Works

(7 sluice gates)

Des Plaines River

at Lockport (DPR-L),

IL (05534050)

Des Plaines River

at Division Street at

Lockport (DPR-DSL),

IL (05534100)

South

Lockport

Materials Road

Division St.

Imagery from U.S. Department of Agriculture, Farm Service Agency,

National Agriculture Imagery Program (NAIP) for Illinois, 2011.

9th Street

Flow

Flow

0 0.5 MILE

0 0.5 KILOMETER

Figure 2. Aerial image of the Lockport Powerhouse, Controlling Works, and Des Plaines River, Illinois, streamgages used to determine 

flow through the Lockport Controlling Works.
Lockport Controlling Works 5

88 4’5" 88 4’ 88 3’55"

41 35’55"

41 35’50"

CSSC at Lockport 

Controlling Works

(CSSC-LCW, IL

(05536998 - base)

0 0.05 MILE

0 0.05 KILOMETER

MWRD tailwater gage

MWRD headwater gage

CSSC at Lockport Controlling Works

(CSSC-LCW), IL (05536998 - auxiliary)

Des Plaines River at

Lockport (DPR-L), IL

(05534050)

Digital imagery from Aerials Express, 2009

1

2

3

4

5

6

7

Flow

Flow

Figure 3. Aerial image of the Lockport Controlling Works and headwater gages and Des Plaines River at Lockport, Illinois, 

streamgage. [CSSC, Chicago Sanitary and Ship Canal; MWRD, Metropolitan Water Reclamation District; USACE, U.S. Army Corps of 

Engineers]
6 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Measurement Summary

To develop a rating for the Lockport Controlling Works, 

streamflow, velocity, and stage data were collected on the Des 

Plaines River and CSSC during March–November 2010 at the 

following locations (figs. 2 and 3):

• Des Plaines River at Lockport (DPR-L) (05534050) 

• Location: Upstream of the controlling-works 

diverted flow

• Data: Continuous stage, index velocity, and 

streamflow 

• Des Plaines River at Division Street at Lockport 

(DPR-DSL) (05534100)

• Location: Downstream of the controlling-works 

diverted flow

• Data: Continuous stage and streamflow 

• Chicago Sanitary and Ship Canal at Lockport 

Controlling Works (CSSC-LCW) (05536998)

• Location: Headwater elevations for the controlling 

works

• Data: Continuous stage

The continuous-stage and streamflow data are stored in the 

USGS National Water Information System (NWIS) database, 

and the daily mean values are available from the USGS Illinois Water Science Center Web site (http://il.water.usgs.gov). 

The discrete measurements for the Des Plaines River gages are 

presented in tables 2 and 3. During an approximately 6-month 

period, there were 9 measurements ranging from 652 to 

6,040 ft3/s at DPR-L, and 10 measurements ranging from 220 

to 10,800 ft3/s at DPR-DSL. Generally the number of transects 

ranged from four to eight per standard USGS methods (Turnipseed and Sauer, 2010). Eight are used if the original four 

are not within a specified percentage of each other. Other factors also contributed to the measurement time of these including the bank operated cableway, fenderwall setup, hydraulic 

conditions, and weather conditions. Stream conditions near 

DPR-L and CSSC-LCW during two storm events when the 

controlling works were in operation are shown in figures 5 

and 6.

Table 2. Streamflow measurements during the study period for 

the U.S. Geological Survey streamflow-gaging station at 

Des Plaines River at Lockport (DPR-L), Illinois (05534050).

[ft3/s, cubic foot per second] 

Measurement 

number Date

Time Measured 

streamflow 

(ft3 Start End /s)

94 03/16/10 14:01 14:20 3,680

95 04/08/10 09:05 09:19 2,780

96 04/16/10 07:43 09:00 1,130

97 05/13/10 10:25 10:56 2,090

98 05/13/10 16:30 16:54 2,210

99 06/16/10 14:43 15:41 1,090

100 07/24/10 18:39 19:02 3,250

101 07/26/10 11:22 11:55 6,040

102 08/23/10 17:25 18:25 652

Table 3. Streamflow measurements during the study period 

for the U.S. Geological Survey streamflow-gaging station at Des 

Plaines River at Division Street at Lockport (DPR-DSL), Illinois 

(05534100).

[ft3/s, cubic foot per second] 

Measurement 

number Date

Time Measured 

streamflow 

(ft3 Start End /s)

2 4/16/2010 7:59 8:05 1,250

3 4/16/2010 8:05 8:45 2,040

4 4/16/2010 9:05 9:33 2,330

5 4/16/2010 9:33 10:01 1,610

6 5/13/2010 12:27 13:00 5,940

7 5/14/2010 12:48 13:07 3,680

8 7/24/2010 20:14 20:26 10,800

9 7/26/2010 9:48 10:13 6,140

10 8/23/2010 17:15 18:24 652

11 10/6/2010 9:41 10:42 220
Lockport Controlling Works 7

Figure 4. Photographs showing A, view looking upstream on the ship canal at the controlling works with all gates closed; and B, view 

looking downstream from the structure toward the Des Plaines River, Illinois.

Figure 5. Photographs showing controlling works with all seven gates open on May 13, 2010, between 11:00 and 12:00 CST. A and 

B, view looking upstream on the ship canal at the controlling works headwater conditions. C, view at the downstream side of the 

controlling works. D, view looking upstream at the Des Plaines River at Lockport, Illinois, streamgage (05534050) with downstream side 

of controlling works in the distance.

A. B.

A.

C.

B.

D.
8 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

A. B.

Figure 6. Controlling works with five gates open on July 24, 2010, at approximately 15:00 CST. A, view of the downstream side of the 

controlling works. B, view looking upstream at the Des Plaines River at Lockport, Illinois, streamgage (05534050) with downstream side 

of controlling works in the distance.

Results

Current (2012) flood-control operational procedure by 

MWRD includes initially lowering the water-surface elevation 

(WSE) in the canal using the powerhouse. The use of the powerhouse limits the effective reductions; therefore, during the 

two storm events (May 13 and July 24–25, 2010) measured 

in this study when the controlling works were in operation, 

the canal WSE ranged from −7.0 to −10.5 ft CCD during the 

stable flow periods (table 4). For the new rating equations 

presented in this section, anything above a canal WSE of 

−7.0 ft is outside the range measured in this study, and more 

importantly, appears to be outside the range of the previously 

developed ratings. During the May event, all seven gates were 

open; during the July event, five gates were open (gates 1, 4, 5, 

6, and 7; see fig. 3 for gate locations). Also, for the data used 

in equation development, the tailwater (DPR-L) to headwater 

(CSSC-LCW-Base) ratios ranged from 0.44 to 0.46 and 0.31 

to 0.66 in the May and July events, respectively. 

A side-view schematic of the sluice gates and parameters 

used in the control-structure rating are shown in figure 7. The 

“measured” flow through the controlling works (QCW) used for 

equation development was determined by subtracting the flow 

at DPR-L (QDPR-L) from DPR-DSL (QDPR-DSL) (in other words, 

QCW = QDPR-DSL – QDPR-L). Forty and 491 flow values were used 

to describe free- and submerged-weir flow through the sluice 

gates, respectively. Conditions of the flow are listed in table 4. 

Only stable flow conditions were used for equation development. Standard weir equations described in Chow (1959), Collins (1977), and Roberson and others (1998) are used in this 

report to describe flow through the sluice gates. Orifice flow 

conditions are not observed at the controlling works because 

the standard operation is to lift the gates completely out of the 

water. 
Lockport Controlling Works 9

Table 4. Number of gates open and flow conditions for two storm events when the controlling works at Lockport, Illinois, were in 

operation.

[—, not applicable]

Event Number of gates 

open

Hours from first 

gate open to last 

gate closed

Flow conditions (hours)

Rapidly

changing Stable Free weir1 Submerged weir2

May 13, 2010 7 10.8 4.0 6.8 1.2 9.6

July 24–26, 2010 5 43.8 6.3 37.5 6.7 37.2

Total — 54.6 10.3 44.3 7.8 46.8

1

Free-weir equation developed using stable flow data from 03:20 to 06:35 on July 24, 2010.

2

Submerged-weir equation developed using stable flow data from 06:50 to 13:30 on May 13, 2010, and 06:40 on July 24 to 16:45 on July 25, 2010.

Headwater elevation

Sluice gate

Tailwater

elevation

h1CW

h3CW

NOT TO SCALE

flow

Concrete sill

elevation

-15.0 ft CCD

EXPLANATION

h1CW

h3CW

Headwater above the

concrete sill

Gate opening

Tailwater above the

concrete sill

hgCW

hgCW

Figure 7. Schematic (side view) of the Controlling Works sluice gates on the Chicago 

Sanitary and Ship Canal at Lockport, Illinois. [ft, foot; CCD, Chicago City Datum]
10 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Utilizing the subtraction of the continuous-flow data 

from the gaging stations (QCW = QDPR-DSL – QDPR-L), the resulting free- and submerged-weir equations are presented later in 

this section and in figure 8. The measured CCW and CCW-S on 

the y-axis in figure 8 are obtained by using QCW and measured 

headwater depth and calculating for the coefficients in equations 2 and 8. The data indicate the following flow-regime 

criteria conditions. Free-weir flow occurs when / h1CW

is less than or equal to 0.37. These data are shown in figure 

8A and correspond to higher coefficients as compared to the 

submerged data (fig. 8B) for the same headwater depths. 

Submerged-weir flow occurs when h3CW

/ h1CWis greater than 

0.37. The value of 0.37 is lower than traditional submergence 

criteria because of the proximity of the tailwater measurement at DPR-L, which is further downstream than a traditional 

tailwater gage (fig. 3). Hart and McGee (1985) recommend 

a tailwater gage location approximately 50 ft due west of the 

current (2012) MWRD tailwater gage (fig. 3). 

Figure 8. Discharge coefficient for A, free-weir flow and B, submerged-weir flow, and the headwater depth for the controlling works 

sluice gates on the Chicago Sanitary and Ship Canal near Lockport, Illinois. [R2, coefficient of determination]

h3CW

y = 0.679x 0.704

R2 = 0.91

2.0

2.5

3.0

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Measured free-weir coefficient (CCW)

Headwater depth (h1CW), in feet

y = 0.479x 0.829

R2 = 0.91

1.0

1.5

2.0

2.5

3.0

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Measured submerged-weir coefficient (CCW-S) 

Headwater depth (h1CW), in feet

A.

B.
Lockport Controlling Works 11

Free-weir (FW) flow occurs when 

 (1)

FW flow equations developed for canal headwater elevations (HWCW) ranging from −7.0 to −10.5 ft CCD

 (2)

(3)

(4)

 (5)

 (6)

where

h3CW is tailwater depth above the sluice-gate sill, in 

ft (measured at gage DPR-L);

h1CW is headwater depth above the sluice-gate sill, 

in ft (measured at gage CSSC-LCW);

QCW is flow through the controlling works, in ft3

/s;

CCW is free-weir coefficient for the sluice gates;

HWCW is canal headwater elevation near the 

controlling works in CCD, in ft;

BCW is length of gates, in ft; and

NCW is number of gates open.

Submerged-weir (SW) flow occurs when 

 

(7)

SW flow equations developed for canal headwater elevations (HWCW) ranging from −7.0 to −10.5 ft CCD

(8)

(9)

(10)

(11)

 (12)

where

h3CW is tailwater depth above the sluice-gate sill, in 

ft (measured at gage DPR-L);

 is headwater depth above the sluice-gate sill, 

in ft (measured at gage CSSC-LCW); QCW is flow through the controlling works, in ft3

/s;

CCW −S is submerged-weir coefficient for the sluice 

gates;

HWCW is canal headwater elevation near the 

controlling works in CCD, in ft; BCW is length of gates, in ft; and

NCW is number of gates open.

The discrete measured and computed sluice-gate flows 

for the controlling works are presented, for comparison, in 

figure 9. Of the 531 computed sluice-gate flow values, all but 

3 are within 10 percent of measured flows. The slope of weir 

coefficient and headwater depth relation appears to be leveling off for headwater depths above 7.5 ft (equals headwater 

elevations greater than −7.5 ft CCD) (fig. 8). Measurements at 

higher headwater depths are needed to verify this preliminary 

observation.

h

h

CW

CW

3

1

≤ 0 3. 7

Q C B h CW CW CW CW = 1

1 5.

C h CW CW = 0 679 1

0 704 . .

h HW ft 1CW CW = +15

B N CW CW = × ft = NCW 30 30

Q N CW = + 20 37 CW CW HW 15 2 204 . ( ) .

h

h

CW

CW

3

1

> 0 3. 7

Q C B h CW CW S CW CW = − 1

1 5.

C h CW S− CW = 0 479 1

0 829 . .

h HW ft 1CW CW = +15

B N CW CW = × ft = NCW 30 30

Q N CW = + 14 37 CW CW HW 15 2 329 . ( ) .

h1CW
12 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

3,000

4,000

5,000

6,000

7,000

8,000

9,000

3,000 4,000 5,000 6,000 7,000 8,000 9,000

Computed flow, in cubic feet per second

Measured flow, in cubic feet per second

Line of perfect agreement

Figure 9. Comparison of continuous-flow data measured at U.S. Geological Survey streamflow-gaging stations and flow computed 

using the 2011 equations for the controlling works sluice gates on the Chicago Sanitary and Ship Canal near Lockport, Illinois.

Flow ratings for the controlling works sluice gate from 

1947, 1985, and 2011 are shown in figure 10. Note that the 

2011 ratings (developed in this study) should be used only 

for headwater elevations ranging from −7.0 to −10.5 ft CCD, 

which is the elevation range of the data collected. Also, the 

1985 study contains 46 pages of tables on how to adjust the 

rating for submergence based on tailwater, which are not 

represented in the rating on figure 10, but are discussed in 

reference to figure 11. 

Continuous-flow data at the controlling works on May 

13, 2010, and July 24–25, 2010, and computed flow using 

the 1947, 1985, and 2011 methods are presented in figure 11. 

The 1947 method overpredicts flow through the gates. The 

1985 method matches the measured flow well if a submergence adjustment is made. The MWRD tailwater data were 

not recoverable for these events, so various submergence 

adjustments were made until the 1985 method matched the 

measured flow. The adjustments were 35 and 18 percent 
Lockport Controlling Works 13

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

-14 -12 -10 -8 -6 -4 -2 0

Flow per gate, in cubic feet per second

Headwater elevation, in feet

1947

1985 Gates 1−5

1985 Gates 6 and 7

2011 Free weir

2011 Submerged weir

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

-14 -12 -10 -8 -6 -4 -2 0

Flow per gate, in cubic feet per second

Headwater elevation, in feet

1947

1985 Gates 1-5

1985 Gates 6 and 7

2011 Free weir

2011 Submerged weir

This range of headwater 

elevations are outside the 

range of data collected for 

the 2011 ratings. These 

ratings should not be used 

for this range of headwater 

elevations. 

A.

B.

Figure 10. Flow per controlling works sluice gate and headwater elevation for 1947, 1985, and 2011 ratings and illustrating, A, the 2011 

ratings should be used only for the headwater elevations ranging from -7.0 to -10.5 feet Chicago City Datum, which is the elevation range 

that the data were collected and, B, that use of 2011 ratings in the shaded zone above -7.0 feet might result in erroneous flow values.
14 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

0

2,000

4,000

6,000

8,000

10,000

12,000

7/23/2010 

23:00

7/24/2010 

6:00

7/24/2010 

13:00

7/24/2010 

20:00

7/25/2010 

3:00

7/25/2010 

10:00

7/25/2010 

17:00

Controlling works diverted flow, in cubic feet per second 

Measured flow

2011 Computed flow

1947 Computed flow

1985 Computed flow

1985 Computed flow (with 18 percent reduction)

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

5/13/2010 

4:00

5/13/2010 

6:00

5/13/2010 

8:00

5/13/2010 

10:00

5/13/2010 

12:00

5/13/2010 

14:00

5/13/2010 

16:00

Controlling works diverted flow, in cubic feet per second

Measured flow

2011 Computed flow

1947 Computed flow

1985 Computed flow

1985 Computed flow (with 35 percent reduction)

7 gates 

closed 7 gates opened (timing indicated by dashed lines)

Measured results are 

expected to be too 

high when the gates at 

the controlling works 

are closed owing to 

the storage in the 

channel between 

Des Plaines River at 

Lockport and Des 

Plaines River at 

Division Street at 

Lockport streamgages

Figure 11. Controlling works continuous-flow data measured at U.S. Geological Survey streamflow-gaging stations 

and flow computed using 1947, 1985, and 2011 methods.
Lockport Powerhouse 15

reductions for the May and July events, respectively (both are 

within ranges found in Hart and McGee (1985)). However, the 

average submergence coefficients using the DPR-L gage (for 

the period of record used in the equation development) were 

0.45 and 0.55 for the May and July events, respectively. Given 

the reductions needed, the inverse of the submergence coefficients would be expected, but DPR-L was never intended for 

these purposes, and there is uncertainty in what is occurring 

between the water level at DPR-L and the controlling works. 

Lastly, owing to the storage in the channel between DPR-L 

and DPR-DSL, measured results are expected to be too high 

for all computed-flow methods when the gates at the controlling works are in the process of closing.

Example Calculations

Example 1: Free-Weir Flow

The following conditions exist:

Five gates are open

Headwater stage (measured at gage CSSC-LCW) = 

−9.02 ft

Tailwater stage (measured at gage DPR-L) = −13.07 ft

In order to determine the flow regime for the current conditions, convert the stages to depths above the sluice-gate sill. 

The top of the sluice-gate sill is at −15 ft CCD. The headwater 

depth ( h1CW ) and tailwater depth ( h3CW ) are calculated by adding 15 ft to the headwater and tailwater stages, respectively.

h ft 1CW = −9 0. . 2 1+ = 5 5 98

h ft 3CW = −13 07 15 . . + =1 93

h

h

CW

CW

3

1

= 0 3. 2

Because 

h

h

CW

CW

3

1

is less than 0.37, free-weir flow exists. Therefore, use equation 6 to calculate flow:

Q N CW = + 20 37 CW CW HW 15 2 204 . ( ) .

QCW = × 20 37 5 9 × − 02 15 + 2 204 . ( . ) .

Q ft s CW = 5 246 3 , /

Example 2: Submerged-Weir Flow

The following conditions exist:

Seven gates are open

Headwater stage (measured at gage CSSC-LCW) = 

−10.16 ft

Tailwater stage (measured at gage DPR-L) = −12.88 ft

In order to determine the flow regime for the current conditions, convert the stages to depths above the sluice-gate sill. 

The top of the sluice-gate sill is at −15 ft CCD. The headwater 

depth ( h1CW ) and tailwater depth ( h3CW ) are calculated by adding 15 ft to the headwater and tailwater stages, respectively.

h ft 1CW = −10 16 15 . . + = 4 84

h ft 3CW = −12 88 15 . . + = 2 12

h

h

CW

CW

3

1

= 0 4. 4

Because 

h

h

CW

CW

3

1

is greater than 0.37, submerged-weir flow

 exists. Therefore, use equation 12 to calculate flow:

Q N CW = + 14 37 CW CW HW 15 2 329 . ( ) .

QCW = × 14 37 7 1 × − 0 16 1+ 5 2 329 . ( . ) .

Q ft s CW = 3 959 3 , /

Lockport Powerhouse

The Lockport Powerhouse is located adjacent to the 

Lockport Lock (fig. 12). The drainage area at the headwater 

gage (CSSC at Lockport Powerhouse (CSSC-LPH), Illinois, 

05537000) is 740 mi2

. The structure consists of nine 9-ft wide 

by 14-ft high sluice gates with a sill elevation of −28.42 CCD 

and two 10-ft diameter turbines (figs. 12–15).
16 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Figure 12. Aerial image of Lockport Powerhouse structures and headwater and tailwater gages. [CSSC, Chicago Sanitary and Ship 

Canal; ADCP, acoustic Doppler current profiler; MWRD, Metropolitan Water Reclamation District; USACE, U.S. Army Corps of Engineers]
Lockport Powerhouse 17

Approach

ADCP measurements were made at the Lockport Powerhouse structures with a tethered boat on the concrete walkway 

shown in figures 12 and 13. The USGS CSSC-LPH headwater 

gage (auxiliary sensor located outside the drawdown zone) and 

USACE tailwater gage (fig. 12) were used for stage readings.

A review of existing ratings and comparison of computed 

and measured flows was performed. Development of new 

ratings was to be attempted with standard control-structure 

techniques (Chow, 1959; Collins, 1977; Roberson and others, 

1998), but gate openings were configured in several ways 

during the nine measurements. The lack of consistent gate 

configuration precluded the development of new equations; 

however, comparison of measured and computed flow using 

the Hart and McGee (1985) and Muga (1961) methods gives 

insight into the accuracy of the computed values. 

Measurement Summary

Streamflow and stage data were collected on the CSSC at 

the powerhouse during March–November 2010 at the following location (fig. 12):

• CSSC at Lockport (CSSC-LPH) (05537000) (powerhouse gage)

• Location: Headwater elevations for the controlling works

• Data: Continuous stage, discrete streamflow 

measurements

The continuous data are available from the NWIS database at the USGS Illinois Water Science Center. The discrete 

flow measurements for the CSSC-LPH gage are presented in 

table 5. During an approximately 6-month period, there were 

11 measurements ranging from 1,118 to 8,160 ft3/s at CSSCLPH. Measurements 1 and 2, made on May 13, 2010, were 

not usable because flow turbulence pushed the boat against 

the fenderwall, and the acoustic beams from the ADCP were 

reflecting off of the arched walls resulting in biased velocity 

data. The measurement method was adjusted for the remainder 

of measurements by attaching the ADCP to a rope stretched 

across the basin to prevent it from moving too close to the 

arched walls. Additional measurements were made during a 

high-flow event in November 2010 replacing the unusable 

measurements in May. The three sluice gates that were undergoing repairs during previous measurements (7A, B, and C), 

were operational and utilized during the November event. 

Stream conditions at the powerhouse on July 24, 2010, when 

6 of the 9 sluice gates and both turbines were in operation, are 

shown in figure 15.

Results

Development of new rating equations for the powerhouse 

control structures was attempted using standard controlstructure techniques, but the lack of consistent gate configuration precluded the development of new equations. However, 

comparison of measured and computed flow using the Hart 

and McGee (1985) and Muga (1961) methods gives insight 

into the accuracy of the methods. Note that in the powerhouse measurements, the change in canal WSE was less than 

0.3 ft for all measurements—except measurement 8—where 

the canal dropped by more than 1 ft (table 5). Also, note the 

changes being made to the gates and turbine malfunction 

in measurements 8–10 as footnoted in table 5. Considering 

the extenuating conditions, if additional measurements were 

made, measurements 8–10 could possibly be omitted, but are 

left in this analysis as they add value to the comparison of 

measured and computed flows. 

Nine measurements, ranging from 1,118 to 8,160 ft3/s, 

were used to compare with USACE (sluice gates) and MWRD 

(turbine) computed flows (table 5 and fig. 16). Turbine flow 

was computed by MWRD by back-calculating flow from 

power production. All four measurements taken while there 

was only turbine flow have computed MWRD turbine flows 

within 30 percent of measured flows. For the five measurements made while there was both turbine and sluice-gate flow, 

the computed USACE and MWRD flows range from 10 to 

more than 100 percent different than measured flows. 
18 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Figure 13. Photographs showing Lockport Powerhouse structures. A, view looking downstream at structure and acoustic Doppler 

current profiler measurement being made on July 24, 2010, utilizing the fenderwall. B, fenderwall during dry conditions in 1907.

A.

B.
Table 5. Flow measurements during the study period for the U.S. Geological Survey streamflow-gaging station at the Chicago Sanitary and Ship CanIllinois (05537000), and computed flows from Hart and McGee (1985) and the Metropolitan Water Reclamation District.[USGS, U.S. Geological Survey; CST, central standard time; ft3/s, cubic foot per second; HW, headwater; ft, foot; TW, tailwater; USACE, U.S. Army Corps of Engineers; C/M,c

sured flow; —, not applicable]

USGS

measurement

number1

Measured

total

streamflow

(M) (ft3/s)

HW

Stage5

USGS 

(HW) (ft)

Change in

HW for

duration

(ft)

TW

stage5

USACE 

(TW) (ft)

Sluice gates Turbine 

Gate

configuration

Computed6

flow (S)

(ft3/s)

Configuration Computed7 flow (T) (ft3/s) Time (CST) Date Start End 

3 07/24/2010 16:49 17:36 8,160 −8.41 −0.03 -37.51 3ABC, 

4ABC

13,906 1, 2 3,000 

4 07/24/2010 18:35 19:15 8,000 −8.45 −.04 -37.52 3ABC, 

4ABC

13,894 1, 2 3,000 

5 07/26/2010 07:02 08:27 2,460 −3.53 .01 -39.24 — 0 1 2,300 6 07/26/2010 13:33 15:07 2,280 −2.93 .21 -39.48 — 0 1, 2 3,000 7 08/23/2010 14:35 15:24 1,118 −2.74 −.27 -40.46 — 0 1 1,000 

28 11/23/2010 10:06 11:31 4,494 −3.54 −1.15 -41.82 7B 2,561 1 1,500 

3, 49 11/23/2010 11:31 12:42 4,224 −3.93 −.15 -41.59 7BC 5,017 1 1,500 

410 11/23/2010 12:43 13:46 6,038 −4.35 −.05 -41.48 7ABC 7,822 — 0 

11 11/23/2010 14:53 14:58 2,165 −4.38 .28 -41.00 — 0 1, 2 2,400 

1Measurements 1 and 2 on May 13, 2010, were not usable because flow turbulence pushed the boat against the fenderwall and the beams were hitting the arched walls (m

the remainder of measurements).

2Sluice Gate 7B opened during measurement, and prior to measurement barge went through lock (upstream to downstream).3Sluice Gate 7C opened during measurement.4Turbines stopped operating during measurement 9 and were not operating during all of measurement 10, per USGS field note.5Averaged over the time of the measurement. 6Sluice gate computation information from Hart and McGee, 1985.7Determined by Metropolitan Water Reclamation District.
20 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Figure 14. Lockport bay section showing the intricacies of flow (modified from Hart and McGee, 1985)

A side-view schematic of the sluice gates and parameters 

used in the rating evaluation by Hart and McGee (1985) are 

shown in figure 14. The three flow conditions and equations as 

described in the 1985 study are

Condition Equation

Sluice-gate control:

(no tailwater effect) Q C= A g2 H1 (13)

Draft-tube control:

(tailwater effect) Q C= A g H ' 2 ∆ (14)

Critical flow:

(no tailwater effect) Q w = 3 09 H1

3 2 . / (15)

where

Q is discharge, in ft3

/s;

C is discharge coefficient, sluice gate;

A is gate area, in ft2

;

g is gravitational acceleration constant, 32.2, in 

ft2/s;

H1 is total upstream head on the gate sill, in ft;

C' is discharge coefficient, overall structure;

∆H is total head loss, in ft; and

w is gate width, in ft.

Note that equation 14 is one form of a submerged sluice-gate 

orifice flow equation, and that ∆H is the head loss from the 

canal headwater to the canal tailwater as shown in figure 14. 

However, Chow (1959) stated the following regarding the 

orifice equations: 

“For the purpose of experimental studies, ... The 

form of this equation is the same for both free and 

submerged flows.” 

In other words, to develop the submerged-orifice equation 

(equation 14); Chow (1959) and Roberson and others (1998) 

show the same orifice equation for free and submerged flows 

, and this approach was successfully applied 

in Straub and others (2009). Essentially, ∆H is not used in 

the submerged-flow equation; however, the determination of 

the coefficient value is based on the relation of the H1 to the 

tailwater elevation. Also, any submergence coefficient or ∆H

calculation should most likely consider the tailwater elevation 

in the chamber before the flow enters the draft tubes (figs. 14 

and 17) (instead of the canal tailwater). 

Upper pool varies Vent holes

Control gates

Draft tubes

V1 Y1

b

EL -28.42

EL -62.0

EL -40.0

EL +2

H1 H

q

Hd

Ccb

2g

V 1

2

Q C= A g2 H1
Lockport Powerhouse 21

Figure 15. Photographs showing Lockport 

Powerhouse headwater and tailwater conditions 

on July 24, 2010. A, view downstream at headwater 

conditions of sluice gates 3A, B, and C; 4A, B, and C; 

and turbine gates 1 and 2 at 17:30 CST. B, conditions 

upstream and downstream of trash guard for sluice 

gate 4C. C, view of tailwater conditions downstream 

of the Lockport Powerhouse at 19:15 CST.

B. C.

A.
22 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

0

3,000

6,000

9,000

12,000

15,000

18,000

0 3,000 6,000 9,000 12,000 15,000 18,000

MWRD (turbine) and USACE (sluice gate) computed total flow, 

in cubic feet per second

USGS measured total flow, in cubic feet per second

Line of perfect agreement

Figure 16. Measured and computed flows for the Lockport Powerhouse on the Chicago Sanitary and Ship 

Canal near Lockport, Illinois. [MWRD, Metropolitan Water Reclamation District of Greater Chicago; USACE, 

U.S. Army Corps of Engineers; USGS, U.S. Geological Survey]
Lockport Powerhouse 23

Figure 17. Selected photographs (from Muga, 1961) showing Lockport Powerhouse flow conditions as modeled 

by Muga, 1961.
24 Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois

Potential Future Work

The results presented in this report are for conditions 

observed during a period of less than one year. If additional 

conditions were to be measured, potential suggestions for how 

to build on the results from this study are outlined in the following sections.

Controlling Works

• Tailwater comparisons 

• Compare stages at three locations: DPR-L gage, 

MWRD tailwater gage, and the recommended tailwater location (Hart and McGee, 1985); then evaluate submergence coefficients 

• Measure flow when various numbers of gates are open

• Measure flow from the catwalk on the downstream side of 

the structure

• Conditions exist (figs. 5 and 6) such that a tethered 

boat can be launched from the structure itself and 

not only complement the continuous data from the 

two Des Plaines River gages, but also give additional 

information on the flow through each gate 

• Measure diverted flow for a broader range of canal WSE 

elevations 

• Lower the canal WSE using the controlling works 

instead of the powerhouse so that the new ratings 

can be extended

Powerhouse

• Measure flow for a broader range of canal elevations and 

systematic gate operations

• Measure tailwater below the vent holes (figs. 14 and 17)

• Reevaluate the submergence equations for the powerhouse using the proposed new data and data from 

the Muga (1961) study. 

• Devise a system for continuous measurement of flow 

(index-velocity rating methods) at the powerhouse

Summary 

The U.S. Army Corps of Engineers (USACE) and the 

Metropolitan Water Reclamation District of Greater Chicago 

(MWRD) regulate flows through control structures along the 

Lake Michigan lakefront and the Chicago Sanitary and Ship 

Canal (CSSC). New acoustic technologies for measuring 

velocity and flow are being used to determine flow for Lake 

Michigan diversion accounting, flood control, sanitary, and 

navigation purposes. These advanced technologies provide an 

opportunity to evaluate the ratings for flow through the control 

structures near Lockport, Illinois. The evaluation and analysis 

were done in 2010 and 2011 by the U.S. Geological Survey 

(USGS), in cooperation with the USACE. 

The LCW is located 2.1 miles upstream of the Lockport 

Lock and Powerhouse. The drainage area at the headwater 

gage (05536998 CSSC-LCW, Illinois) is 739.5 square miles 

(mi2). The structure consists of seven 30-feet (ft) wide sluice 

gates and is used to divert water from the CSSC into the Des 

Plaines River. The flow regimes for the sluice gate included 

both free and submerged weir. Forty and 491 flow values 

from U.S. Geological Survey streamflow-gaging stations were 

used to describe free- and submerged-weir flow, respectively, 

through the sluice gates. The equations were developed for 

canal headwater elevations ranging from −7.0 to −10.5 ft 

Chicago City Datum (CCD), and tailwater (Des Plaines River 

at Lockport) to headwater (CSSC-LCW-Base) ratios ranging 

from 0.31 to 0.66.

The Lockport Powerhouse is located adjacent to the 

Lockport Lock. The drainage area at the headwater gage 

(05537000 CSSC-LPH, Illinois) is 740 mi2

. The structure 

consists of nine 9-ft wide by 14-ft high sluice gates and two 

10-ft diameter turbines. Both tailwater and no tailwater effect 

flow regimes occurred during nine measurements. Also, the 

canal headwater elevations ranged from −2.74 to −8.45 ft 

CCD, and the gates were configured six different ways during 

the measurements.
References Cited 25

References Cited 

Aerials Express (Chicago Imagery), 2009, ArcGIS Map Service, http://services.arcgisonline.com/arcgis/services/.

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

McGraw-Hill, 680 p.

Collins, D.L., 1977, Computation of records of streamflow at 

control structures: U.S. Geological Survey Water-Resources 

Investigations Report 77–8, 57 p.

Hart, E.D., and McGee, R.G., 1985, Lockport power plant 

sluice gate and control works discharge evaluation: U.S. 

Army Engineer Waterways Experiment Station Hydraulics 

Laboratory Miscellaneous Paper HL–85–4, 105 p.

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., accessed February 13, 

2011, at http://pubs.usgs.gov/wri/2001/wri01_4157/. 

Muga, B.J., 1961, The Lockport sluice gate model study: 

Urbana, University of Illinois, Department of Civil 

Engineering, M.S. thesis, 111 p.

Roberson, J.A., Cassidy, J.J., and Chaudhry, M.H., 1998, 

Hydraulic engineering (2d ed.): New York, Wiley, 653 p.

Ruhl, C.A., and Simpson, M.R., 2005, Computation of discharge using the index-velocity method in tidally affected 

areas: U.S. Geological Survey Scientific Investigations 

Report 2005–5004, 41 p., accessed February 13, 2012, at 

http://pubs.usgs.gov/sir/2005/5004/. 

Straub, T.D., Johnson, G.P., Hortness, J.E., and Parker, 

J.R., 2009, Control-structure ratings on the Fox River at 

McHenry and Algonquin, Illinois: U.S. Geological Survey 

Scientific Investigations Report 2009–5186, 61 p., accessed 

February 13, 2012, at http://pubs.usgs.gov/sir/2009/5186/. 

Turnipseed, D.P., Sauer, V.B., Discharge measurements at 

gaging stations: U.S. Geological Survey Techniques and 

Methods book 3, chap. A8, 87 p. (Also available at http://

pubs.usgs.gov/tm/tm3-a8.) 

U.S. Department of Agriculture, 2011, Farm Service Agency, 

National Agriculture Imagery Program (NAIP), ArcGIS 

Map Service, http://gis.apfo.usda.gov/arcgis/services/.

Straub and others—Control-Structure Ratings on the Chicago Sanitary and Ship Canal near Lockport, Illinois—Scientific Investigations Report 2012–5131