Long Term Resource Monitoring Program

Technical Report 

2004-T004

September 2004

A Suspended Sediment Budget for 

Pool 13 and La Grange Pool of the 

Upper Mississippi River System
Long Term Resource Monitoring Program Technical Reports 

provide Long Term Resource Monitoring Program 

partners with scientific and technical support.

All reports in this series receive anonymous peer review.

Mention of trade names or commercial products does not constitute endorsement

or recommendation for use by the U.S. Department of the Interior, U.S. Geological Survey.
A Suspended Sediment Budget for 

Pool 13 and La Grange Pool of the 

Upper Mississippi River System

by

Robert F. Gaugush

U.S. Geological Survey

Upper Midwest Environmental Sciences Center

 2360 Fanta Reed Road

 La Crosse, Wisconsin 54603

Final Report to

U.S. Army Corps of Engineers

Rock Island, Illinois

for

Long Term Resource Monitoring Program 

Scope of Work 3.4

(Suspended Sediment Budgets for Pool 13 and La Grange Pool)

September 2004
Suggested citation:

Gaugush, R. F. 2004. A suspended sediment budget for Pool 13 and La Grange Pool of the Upper Mississippi 

River System. Final report to U.S. Army Corps of Engineers. U.S. Geological Survey, Upper Midwest 

Environmental Sciences Center, La Crosse, Wisconsin. September 2004. LTRMP 2004-T004. 

13 pp. + Appendixes A–D.

Additional copies of this report may be obtained from the National Technical Information Service, 5285 

Port Royal Road, Springfield, VA 22161 (1-800-553-6847 or 703-487-4650). Also available to registered 

users from the Defense Technical Information Center, Attn: Help Desk, 8725 Kingman Road, Suite 0944, Fort 

Belvoir, VA 22060-6218 (1-800-225-3842 or 703-767-9050).
iii

Contents

Page

Preface ................................................................................................................................................v

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

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

Study area .............................................................................................................................................2

 Pool 13 ...........................................................................................................................................2

 La Grange Pool ..............................................................................................................................3

Methods ................................................................................................................................................3

Results and discussion .........................................................................................................................5

 Pool 13 ...........................................................................................................................................5

 La Grange Pool ..............................................................................................................................8

 Comparison of Pool 13 and La Grange Pool ...............................................................................10

Conclusion .........................................................................................................................................11

Acknowledgments ..............................................................................................................................12

References ............ ..............................................................................................................................12

Appendix A ......................................................................................................................................A-1

Appendix B ...................................................................................................................................... B-1

Appendix C ...................................................................................................................................... C-1

Appendix D ...................................................................................................................................... D-1
iv

Tables

Number Page

1. U.S. Geological Survey station names and station codes for the gaging stations used in 

developing the suspended sediment budget for Pool 13 ...............................................................4

2. U.S. Geological Survey station names and station codes for the gaging stations used in 

developing the suspended sediment budget for La Grange Pool ..................................................4

3. Drainage areas for Pool 13 ............................................................................................................4

4. Drainage areas for La Grange Pool ...............................................................................................4

5. Land use in the watersheds of Pool 13 and La Grange Pool .........................................................6

Figures

1. Map of the Upper Mississippi River System .................................................................................3

2. Annual water budgets and annual suspended sediment budgets for Pool 13 ................................5

3. Pool 13 monthly water and suspended sediment budgets for the 1995, 1996, and 1997 

water years ..... 7

4. Pool 13 suspended sediment balance ...........................................................................................8

5. Annual water budgets and annual suspended sediment budgets for La Grange Pool ...................8

6. La Grange Pool monthly water and suspended sediment budgets for the 1995, 1996, and 

1997 water years ..........................................................................................................................10

7. La Grange Pool suspended sediment balance ............................................................................11
v

Preface

 The Long Term Resource Monitoring Program (LTRMP) was authorized under the Water 

Resources Development Act of 1986 (Public Law 99-662) as an element of the U.S. Army Corps of 

Engineers’ Environmental Management Program. The LTRMP is being implemented by the Upper 

Midwest Environmental Sciences Center, a U.S. Geological Survey science center, in cooperation 

with the five Upper Mississippi River System (UMRS) States of Illinois, Iowa, Minnesota, Missouri, 

and Wisconsin. The U.S. Army Corps of Engineers provides guidance and has overall Program 

responsibility. The mode of operation and respective roles of the agencies are outlined in a 1988 

Memorandum of Agreement.

 The UMRS encompasses the commercially navigable reaches of the Upper Mississippi 

River, as well as the Illinois River and navigable portions of the Kaskaskia, Black, St. Croix, and 

Minnesota Rivers. Congress has declared the UMRS to be both a nationally significant ecosystem 

and a nationally significant commercial navigation system. The mission of the LTRMP is to provide 

decision makers with information for maintaining the UMRS as a sustainable large river ecosystem 

given its multiple-use character. The long-term goals of the Program are to understand the system, 

determine resource trends and effects, develop management alternatives, manage information, and 

develop useful products.

 This report supports LTRMP Operating Plan (U.S. Fish and Wildlife Service 1993) Task 

1.2.1.2 Select Processes for Research, and Tasks 1.2.1.3, Establish Experimental Design, under 

Strategy 1.2.1, Determine Effects of Sedimentation and Sediment Transport Processes on the Upper 

Mississippi River System Ecosystem. This report was developed with funding provided by the Long 

Term Resource Monitoring Program.

A Suspended Sediment Budget for 

Pool 13 and La Grange Pool of the 

Upper Mississippi River System

Final Report to

U.S. Army Corps of Engineers

Rock Island, Illinois

for

Long Term Resource Monitoring Program 

Scope of Work 3.4

(Suspended Sediment Budgets for Pool 13 and La Grange)

by

Robert F. Gaugush

U.S. Geological Survey

Upper Midwest Environmental Sciences Center

 2360 Fanta Reed Road

 La Crosse, Wisconsin 54603

Abstract: The suspended sediment budget for Pool 13 of the Mississippi River and La Grange 

Pool of the Illinois River was examined over a 3-yr period (October 1995 through September 

1997). Pool 13 output was between 3.07 and 3.64 million t (metric tons) of suspended sediment 

annually during the study period. Loads to Pool 13 were dominated by those delivered by the 

Mississippi River (76%, 74%, and 66% in the 1995, 1996, and 1997 water years, respectively). 

Pool 13 exhibited sediment export (output greater than input) in 1995, a balance in 1996, and 

marked sediment trapping (output less than input) in 1997. Within the three study years, Pool 

13 received its highest water and sediment loads during spring (March through May) and this 

period was marked by sediment export. Suspended sediment loads were trapped during the 

remainder of the year. La Grange Pool output was between 3.71 and 5.04 million t of suspended 

sediment annually during the 1995–97 water years. The Illinois River accounted for less than 

50% of the suspended sediment load to the pool (19%, 25%, and 45% in the 1995, 1996, and 

1997 water years, respectively. La Grange Pool exhibited considerable sediment trapping in 

1995 whereas the 1996 and 1997 water years were much closer to a balance wherein output was 

within 5% of input. Generally, La Grange Pool received its largest water and sediment loads 

during the late spring–early summer period (April through June), but in 1997 the late winter 

loads predominated. In all years, La Grange Pool trapped the sediments during these high 

discharge, high loading periods and exported suspended sediments for the remainder of the year. 

The distinct differences in the manner in which these pools process suspended sediment loads 

may be related to the considerable differences between the morphometry of these pools.

Key words: La Grange, Mississippi River, Pool 13, river, sediment budget, sediment load
2

Introduction

The Upper Mississippi River System 

(UMRS), defined as the navigable portions of the 

Mississippi and Illinois Rivers, has been directly 

affected by human activities (activities in the river 

channel itself, rather than in the watershed) such 

as the construction of wing dams and side channel 

closing structures for at least 120 yrs, but the most 

severe alteration occurred with the construction 

of a series of locks and dams in the late 1930s. 

Initially, impoundment of these rivers created a 

very diverse mosaic of physical features such as 

islands, braided channels, and backwater lakes. 

On the Mississippi River, the construction of the 

navigation system created a series of shallow 

impoundments occupying most of the floodplain. 

Whereas the initial filling of these areas was seen 

as a boon to the overall physical heterogeneity, 

it was soon apparent that the hydrological 

changes brought about by impoundment were 

having considerable effects on sedimentation 

processes (Fremling and Claflin 1984). A general 

pattern was observed involving island loss and 

excessive backwater sedimentation. This erosion 

of high points and filling in of low points led to 

a considerable loss of physical heterogeneity. 

Essentially the same process (impoundment) that 

led to their creation would also be responsible 

for the demise of the islands, braided channels, 

and backwater lakes. Similar changes have been 

observed in the Illinois River (Sparks 1984). 

Increased sedimentation, primarily in off-channel 

areas, has for some time been recognized as a 

major concern and has been identified as one of 

the primary threats to the ecological resources 

of the Upper Mississippi River (Great River 

Environmental Action Team 1980).

Most previous sediment budget studies on the 

Mississippi and Illinois Rivers have focused on 

large-scale (a long reach or the entire river) and 

have been based on relatively few data. Nakato 

(2000) assembled the available data and developed 

a sediment budget, which included estimates 

of bedload, for Pools 11–26 on the Mississippi 

River for two long periods: post-impoundment 

to the mid-1950s and mid-1950s to the present. 

A major finding of Nakato’s study (2000) was 

that sediment loading is lower in the more 

recent period. Demissie et al. (2003) produced 

a sediment budget for the Illinois River for 

1981–94. Data from the Illinois River indicated 

that, on the average, 12.4 million t (metric tons; 

1 metric ton = 1,000 kg) of sediment are delivered 

to the system every year and the system exports 

an average of 5.3 million t. Approximately 

7.2 million t are stored in the system.

 A workshop held in 1994 identified the 

serious need to develop pool-scale sediment 

budgets for the navigation pools of the UMRS 

(Gaugush and Wilcox 1994). Pool-scale budgets 

wherein the in-pool processes were viewed as a 

“black box” were seen, collectively, as a necessary 

first step in developing an understanding of 

sediment processing in the UMRS. Pool 13 on 

the Mississippi River and La Grange Pool on the 

Illinois River were chosen as the first sites for this 

type of study. The objectives of this study were to

1. determine the suspended sediment budget in 

two distinctly different navigation pools of the 

UMRS;

2. determine if the budgets were dominated by 

sediment storage (input greater than output), a 

quasi-equilibrium (input ≈ output), or export 

(output greater than input); and

3. examine the relation between sediment 

mass flux and the annual dynamics of water 

discharge.

Study Area

Pool 13

Pool 13 is between river miles 522.5 and 

556.8 (measured from the confluence with the 

Ohio River) on the Mississippi River (Figure 1). 

Pool 13 is 1 of 26 pools formed by a series of 

locks and dams constructed in the late 1930s to 

maintain a 9-foot channel as an aid to commercial 

navigation. Construction of Lock and Dam 13 was 

completed in 1938 and placed in operation in 1939 

(U.S. Army Corps of Engineers 1980). Four small 

rivers discharge into Pool 13: the Maquoketa and 

Elk Rivers on the Iowa (western) side of the pool 

and the Apple and Plum Rivers on the Illinois 

(eastern) side. Eight additional minor streams 

also discharge into Pool 13. Mean discharge 
3

from Pool 13 is 1379 m3 s-1 for the period of 

record (1873–1997) and time of travel for water 

is approximately 10 h during normal operation. 

Pool 13 is in an extended valley segment, the 

walls of which are erosion resistant limestone 

and dolomite formations (Knox 2000). A narrow 

bedrock gorge ends in the upper reach of Pool 13. 

The generally flat floodplain is 2.4 km wide at the 

upper end of Pool 13 and widens to almost 6.4 km 

at the lock and dam.

La Grange Pool

La Grange Pool is between Illinois River 

miles 80.2 and 157.7 (measured from the 

confluence with the Mississippi River; Figure 1). 

La Grange Pool is one of six pools on the Illinois 

River formed by impoundment with locks 

and dams to support commercial navigation. 

As with the system on the Mississippi River, 

these structures were constructed to aid in the 

maintenance of a 9-foot navigation channel. The 

Illinois Waterway serves to provide a commercial 

navigation connection between the Mississippi 

River and Lake Michigan. 

The lock and dam that forms 

La Grange Pool is the most 

downstream of the nine locks 

and dams forming the Illinois 

Waterway. La Grange Lock and 

Dam were constructed and put 

into operation in 1939 (U.S. 

Army Corps of Engineers 1986). 

Four significant rivers enter 

La Grange Pool: the Spoon and 

La Moine Rivers on the northern 

side and the Mackinaw and 

Sangamon Rivers on the southern 

side. Mean discharge for the 

period of record (1939–97) is 

645 m3 s-1 and the mean travel 

time for water is 24–36 hours. 

La Grange Pool occupies the 

ancient course of the Mississippi 

River, which accounts for its low 

gradient and large valley width 

(Knox 2000). The main channel 

is relatively narrow and uniform 

with only a slight widening at 

the lock and dam. An extensive 

A

B C

Figure 1. Map of the Upper Mississippi River System: (A) location of the two pools in the 

upper Midwest of the United States; (B) Pool 13; and (C) La Grange Pool.

series of levees separate most of the floodplain 

from the Illinois River.

Methods

Pool 13 was allocated six gaging sites, one 

upstream of the pool on the Mississippi River, 

one downstream of the pool, and one each for 

the four major tributaries to the pool (Figure 1). 

Gaging stations (Table 1) were established on the 

Mississippi River at the next upstream lock and 

dam, the Apple and Plum Rivers on the Illinois 

(eastern) side, the Maquoketa and Elk Rivers 

on the Iowa (western) side, and the Mississippi 

River below Lock and Dam 13. Drainage area 

is 221,695 km2 at the most downstream station, 

96.3% of which is contributed by the Mississippi 

River and less than 2.5% by the four gaged 

tributaries (Table 2). Only 1.3% of the drainage 

area was not gaged.

La Grange Pool was allocated six gaging 

sites, one upstream of the pool on the Illinois 

River, one downstream of the pool, and one each 
4

for the four major tributaries to the pool (Figure 

1). Gaging stations (Table 3) were established 

on the Illinois River below the next upstream 

lock and dam, the Spoon and La Moine Rivers 

on the northern side of the pool, the Sangamon 

and Mackinaw Rivers on the southern side of the 

pool, and the Illinois River below the La Grange 

Lock and Dam. Drainage area is 69,262 km2 at 

the most downstream station, of which 54.5% is 

contributed by the Illinois River above La Grange 

Pool and 34% by the four gaged tributaries 

(Table 4). Approximately 11.5% of the drainage 

was not gaged and represents the area between the 

tributary gaging stations and the pool, ungaged 

tributaries, and direct drainage into the pool.

At both pools, discharge gaging and 

suspended sediment sampling were conducted 

by the U.S. Geological Survey according to 

established U.S. Geological Survey/Water 

Resources Division (USGS/WRD) methods 

(Buchanon and Somers 1969; Guy and Norman 

1982). Suspended sediment sampling at 

each gaging site consisted of approximately 

250 samples per year with the samples taken 

weekly during base flow conditions and more 

frequent sampling during storm events. Discharge 

measurements were recorded continuously by 

automated equipment. This study was initiated in 

1994 with site preparation and gage installation. 

Actual data collection began in October 1995. 

Sampling was terminated at the end of September 

1997 after 3 yrs of data collection.

The USGS/WRD uses the continuous 

discharge data and the instantaneous suspended 

sediment concentration data to compute mean 

daily water discharge and daily suspended 

sediment loads for each gaging station. These 

mean daily data were used in this study to develop 

the water and suspended sediment budgets for 

Pool 13 and La Grange Pool. These data have 

been published in annual water data reports for 

Illinois and Iowa (May et al. 1996, 1997, 1998; 

Wicker et al. 1996, 1997, 1998).

Table 1. U.S. Geological Survey station names and station 

codes for the gaging stations used in developing the suspended 

sediment budget for Pool 13.

Station name Station code

Mississippi River at Lock & Dam 12 at 

Bellvue, Iowa 05416100

Apple River near Hanover, Illinois 05419000

Plum River at Savanna, Illinois 05420100

Maquoketa River near Maquoketa, Iowa 05418500

Elk River near Altmont, Iowa 05420300

Mississippi River at Clinton, Iowa 05420500

Table 2. U.S. Geological Survey station names and station 

codes for the gaging stations used in developing the suspended 

sediment budget for La Grange Pool.

Station name Station code

Illinois River at Pekin, Illinois 05563800

Mackinaw River near Green Valley, Illinois 05568500

Spoon River at Seville, Illinois 05570000

Sangamon River near Oakford, Illinois 05583000

La Moine River at Ripley, Illinois 05585000

Illinois River at Valley City, Illinois 05586100

Table 3. Drainage areas for Pool 13.

Source

Drainage 

area (km2)

Proportion 

of total (%)

Mississippi River above Pool 13 213,408 96.3

 Apple River 640 0.3

 Plum River 707 0.3

 Maquoketa River 4,022 1.8

 Elk River 145 0.1

Total gaged input 218,920 98.8

Ungaged 2,772 1.3

Output for Pool 13 221,695

Table 4. Drainage areas for La Grange Pool.

Source

Drainage 

area (km2)

Proportion 

of total (%)

Illinois River above La Grange 

Pool 37,775 54.5

 La Moine River 3,349 4.8

 Mackinaw River 2,779 4.0

 Sangamon River 13,190 19.0

 Spoon River 4,237 6.1

 Total gaged input 61,330 88.5

 Ungaged 7,932 11.5

Output for La Grange Pool 69,262
5

Results and Discussion

Pool 13

The drainage area of Pool 13 is dominated 

by that area drained by the Mississippi River that 

contributes just over 96% of the total area. Of 

the remaining 3.7%, 2.5% is contributed by the 

four gaged tributaries of this study and 1.2% is 

ungaged. The predominance of the Mississippi 

River in terms of its contribution to the overall 

drainage area would suggest that the water and 

sediment budgets for Pool 13 will be influenced 

primarily by events or conditions above the pool 

and conditions directly surrounding the pool will 

have a lesser effect. 

The water years of 1995, 1996, and 1997 

were generally wetter than the long-term 

(1873–1997) average (Figure 2, upper), but still 

considerably drier than the major flood year of 

1993. Discharges from the pool were greater 

than 125% of the mean daily discharge for the 

period of record. Input of water to Pool 13 is 

provided predominantly (generally about 95% 

of the amount discharged from the pool) by the 

Mississippi River. The gaged tributaries provide 

only about 3%.

As with most water budgets, there are some 

unknown (i.e., unmeasured) sources and losses 

of water from the pool. A typical assumption 

in the absence of data is that precipitation and 

evaporation are in balance (the amount input 

by precipitation equals the amount lost to 

evaporation). Another unknown source is the sum 

of all inputs from ungaged tributaries and direct 

runoff from the land adjacent to the pool and not 

drained by a stream. To estimate this source, one 

might assume that the ungaged contribution is 

directly proportional to the ungaged drainage area. 

This requires one further assumption, that the 

nature of the ungaged area (its land use, soil types, 

slopes, etc.) is similar to the features of the gaged 

tributaries. Given these assumptions, an export 

coefficient (amount of material exported divided 

by the drainage area) for the gaged tributaries can 

be calculated. This export coefficient multiplied 

by the ungaged drainage area provides an estimate 

of the ungaged contribution to the budget.

Generating ungaged estimates in the above 

manner results in a water budget in balance 

(inputs = outputs) for all water years. There is 

less than a 1% difference between water input 

and water output for the 3 yrs studied (Figure 2, 

upper). Developing a water budget that is in 

balance (given the assumptions made) suggests 

that the sampling design and sample allocation 

should also provide adequate estimates for the 

suspended sediment budget.

Pool 13 exported between 8,500 and 10,000 t 

of suspended sediment on a daily basis during 

the 1995–97 water years (Figure 2, lower). The 

majority (76% in 1995, 74% in 1996, and 66% 

in 1997) of the sediment input to Pool 13 is 

Input Output Input Input

Input Input Input

Output Output

Output Output Output

1995 1996 1997

1995 1996 1997

Water year

Water year

POR

1993

Suspended sediment load, metric tons/day Mean daily discharge, m3/sec

0

500

1000

1500

2000

2500

3000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

Source Mainstem Tributary Ungaged

Source Mainstem Tributary Ungaged

Figure 2. Annual water budgets (upper) and annual suspended 

sediment budgets (lower) for Pool 13. Horizontal reference lines 

indicate mean daily discharge at the downstream end of the Pool 13 

study area for the period of record (POR, 1873–1997) and for the 

1993 flood (1993).
6

supplied by the Mississippi River. Whereas the 

gaged tributaries only accounted for about 3% of 

the drainage area and discharge, they provided a 

greater portion (16% in 1995, 17% in 1996, and 

22% in 1997) of the suspended sediment load. 

These loads are more than five times greater 

than would be expected based solely on these 

tributaries’ contribution to the overall drainage 

area or water input. 

The observation that the gaged tributaries 

contributed more to the sediment budget than 

would be expected based on either their drainage 

area or their water discharge suggests a difference 

in the relation between drainage area and sediment 

delivery. In other words, the local drainage area 

has a greater sediment delivery per unit area than 

the drainage area above the pool. This is not 

an unexpected result because, though the local 

drainage area (that area drained by tributaries that 

enter Pool 13) has a predominantly agricultural 

land use, the area above Pool 13 drained by the 

Mississippi River is more forested with lesser 

agricultural use (Table 5).

at that level. Differences greater than 5% are 

usually indicative of real differences in the budget 

(i.e., input greater than output or input less than 

output).

Given the relative similarity in the water 

budget for the 3 yrs studied, there are considerable 

differences between years in the suspended 

sediment budgets. The data suggest sediment 

export (output greater than input) in 1995, a 

balance in 1996, and marked sediment trapping 

(output less than input) in 1997. Two processes 

in water year 1997 result in a positive sediment 

budget (material is stored in the pool). First, 

tributary loads (and, as a result, the ungaged 

contribution) are somewhat greater than the 

previous 2 yrs. Second, the pool output is 

considerably lower than the previous 2 yrs. This 

observation suggests that Pool 13 may process 

tributary loads in a manner different from 

mainstem loads.

The nature of the observed change in the 

1997 suspended sediment loading cannot be 

derived from a simple examination of the annual 

estimates. Determining why Pool 13 apparently 

trapped sediments in 1997 will require a closer 

examination of the dynamics and timing of 

events within the year. The pattern of changing 

conditions during the year most likely will affect 

the annual estimate. For example, the timing of 

large loading events (when they occur within the 

year, such as in spring instead of summer or fall) 

may have a large effect on whether the suspended 

load is trapped by the system or passed through it.

The Mississippi River and gaged tributaries 

to Pool 13 exhibited the expected annual patterns 

of water discharge and suspended sediment loads. 

Discharges were at their lowest in the winter 

(December through February), rose to their peak 

in the spring (April and May), fell through the 

summer (June through September), and generally 

rose to a smaller peak in the fall (October and 

November) before dropping back to the winter 

minimum (Figure 3; upper, middle, and lower 

left). Suspended sediment loads, not surprisingly, 

followed the same general pattern through the 

year (Figure 3; upper, middle, and lower right). 

Sediment loads from the Mississippi River 

The same assumptions used to estimate the 

contribution of water from the ungaged areas were 

used to estimate the contribution of those areas to 

the suspended sediment load. Ungaged estimates 

were half (8% in 1995, 8% in 1996, and 11% in 

1997) the sediment contribution from the gaged 

tributaries because the ungaged drainage area 

was approximately 50% of the gaged tributary 

drainage area.

Typically when budgets show a difference of 

about 5% or less they are said to be in balance. 

Errors associated with the data and the estimation 

of ungaged sources cannot distinguish differences 

Table 5. Land use (expressed as percent of the total drainage 

area) in the watersheds of Pool 13 and La Grange Pool.

Land Cover/Use Pool 13 La Grange Pool

Agriculture 57.9 83.6

Deciduous forest 13.1 5.8

Evergreen forest 2.2 0.1

Forested wetland 5.5 0.5

Mixed forest 13.4 0.1

Other 7.9 9.9
7

generally exceeded the contribution of sediments 

from the tributaries, but there were three 

exceptions to this general behavior, all of which 

occurred in the 1997 water year. The month of 

February 1997 was marked by an extremely large 

sediment load from the tributaries. The months of 

March and June 1997 were also months of high 

tributary sediment loading. These same months 

(February, March, and June 1997) also showed 

larger than usual tributary contributions to the 

water load. Suspended sediment discharged from 

Pool 13 generally followed the same patterns as 

input sediment loads and water discharge.

The pattern of sediment storage and export in 

Pool 13 is more clearly illustrated by examining 

the net flux (input minus output) behavior in terms 

of metric tons per day and the net flux expressed 

as a percentage of the input (Figure 4; upper and 

lower, respectively). A value of zero for the net 

flux indicates that the inputs (Mississippi River, 

four gaged tributaries, and the ungaged estimate) 

and the downstream output are in balance (i.e., 

as much is leaving as is entering). A positive 

value for the net flux means that inputs exceed 

the output and the pool is trapping or storing 

sediment. A negative net flux occurs when output 

exceeds inputs, which then implies that the pool 

is actually mobilizing previously stored sediment 

and exporting it from the system. Pool 13 exported 

sediment (output is greater than input) during 

the major high flow, high load months of the 

year during all 3 yrs of the study. The periods of 

peak discharge and peak loads (April and May 

in all years) all have negative values for net flux. 

During these months, the pool exports from 125% 

to 175% of the suspended sediment input. In the 

Figure 3. Pool 13 monthly water (left) and suspended sediment budgets (right) for the 1995 (upper), 1996 (middle), and 1997 (lower) water 

years. “I” refers to input to Pool 13 and “O” refers to outputs.

1995

1996

1997

1995

1996

1997

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

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OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

Month Month

Mean daily discharge, 

m3/sec

Suspended sediment load, metric tons/day

Source Mainstem Tributary Ungaged
8

remaining months of the year, Pool 13 traps from 

a few to as much as 90% of the input sediment 

load.

La Grange Pool

The drainage area of La Grange Pool is 

almost evenly split between the area drained by 

the Illinois River and the “local” drainage (area 

between the upstream and downstream ends of the 

pool). The Illinois River drains 55% of the pool’s 

total drainage area and the remaining 45% (34% 

gaged tributaries and 11% ungaged) is local or 

direct. This implies that the water and sediment 

budgets for La Grange Pool will be much more 

influenced by local conditions (storms, land use 

patterns, etc.) than a pool where the mainstem 

might account for most (> 90%) of the input of 

water and sediment.

The 1995 water year was considerably wetter 

than the long-term (1939–97) average (Figure 5, 

upper) but the 1996 and 1997 water years were 

Figure 4. Pool 13 suspended sediment balance (sum of inputs minus 

output) expressed as (A) the metric tons per day of sediment storage 

(positive values, inputs exceed output) and export (negative values, 

outputs exceed inputs) and (B) the percentage of the input sediment 

load that is stored or exported.

A

B

O D F A J A O D F A J A O D F A J A 

C E E P U U C E E P U U C E E P U U

T C B R N G T C B R N G T C B R N G 

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 4 4 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7

 Month and year

O D F A J A O D F A J A O D F A J A 

C E E P U U C E E P U U C E E P U U

T C B R N G T C B R N G T C B R N G 

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 4 4 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7

 Month and year

75000

60000

45000

30000

15000

0

-15000

100

50

0

-50

-100

-150

-200

-250

-300

Suspended sediments, metric tons/day

Percent of Input

1993

POR 

1,400

1,200

1,000

800

600

400

200

0

17,000

16,000

15,000

14,000

13,000

12,000

11,000

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

Input Output Input Output Input Output

Input Output Input Output Input Output

1995 1996 1997

Water year

1995 1996 1997

Water year

Suspended sediment load, metric tons/day Mean daily discharge, m3/sec

Source Mainstem Tributary Ungaged

very close to normal. Discharge in 1995 was 

almost 130% of the mean daily discharge for the 

period of record. The Illinois River contributes the 

majority of the water input (58% in 1995, 66% in 

1996, and 72% in 1997) to La Grange Pool.

Ungaged contributions to the La Grange Pool 

water budget were estimated in the same manner 

described above for Pool 13. Generating ungaged 

estimates in the above manner results in a water 

budget that is in balance (input equals output) for 

all water years. There is less than a 1% difference 

between water input and water output for the 3 yrs 

studied. Again, these results for the water budget 

suggest that the sampling design and sample 

Figure 5. Annual water budgets (upper) and annual suspended 

sediment budgets (lower) for La Grange Pool. Horizontal reference 

lines indicate mean daily discharge at the downstream end of the 

La Grange Pool study area for the period of record (POR 1938–1997) 

and for the 1993 flood (1993).
9

allocation should also provide adequate estimates 

for the suspended sediment budget.

La Grange Pool annually exported between 

10,000 and 14,000 t of suspended sediment on 

a daily basis during the 1995–97 water years 

(Figure 5, lower). In all years, the Illinois River 

above La Grange Pool accounted for less than 

50% of the suspended sediment load to the pool 

(19% in 1995, 25% in 1996, and 45% in 1997). 

The gaged tributaries accounted for only 34% 

of the total drainage area, but they account for a 

much greater portion of the sediment load (61% 

in 1995, 56% in 1996, and 41% in 1997). These 

loads are from 1.2 to 2 times higher than would 

be expected based solely on these tributaries’ 

contribution to the overall drainage area or water 

input. This greater than expected contribution 

from the gaged tributaries implies that the local 

watershed has a greater sediment delivery per unit 

area than the drainage area above the pool.

The same assumptions used to estimate the 

contribution of water from the ungaged areas were 

used to estimate the contribution of these areas to 

the suspended sediment load. Ungaged loads were 

estimated to be 34% of the sediment contribution 

from the gaged tributaries because the ungaged 

drainage area was approximately 34% of the 

gaged tributary drainage area.

The wet year of 1995 is associated with 

considerable sediment trapping (input greater than 

output) whereas the water years of 1996 and 1997 

seem to be in balance (less than a 5% difference 

between input and output; Figure 5, lower). These 

data suggest that La Grange Pool traps sediment 

during flood years but is nearly in balance in more 

hydrologically normal years.

The Illinois River and the gaged tributaries 

to La Grange Pool exhibited annual patterns of 

water discharge and suspended sediment loads 

that were different from those observed in Pool 

13. In the 1995 and 1996 water years, discharges 

were at their lowest in the late summer–early fall 

(September and October), slowly rose to their 

peak in the late spring–early summer (May and 

June), and then slowly fell to the fall minimum 

(Figure 6, upper and middle left). The 1997 water 

year exhibited a late winter–early spring (February 

and March) peak discharge with only a slight 

increase in flows in June (Figure 6, lower left). 

During all periods of peak discharge, the tributary 

and the estimated ungaged contributions make 

up a large proportion of the total water load to 

La Grange Pool. In May of 1995 and 1996, these 

contributions exceed those of the Illinois River. 

Suspended sediment loads followed the same 

general pattern through the year (Figure 6; upper, 

middle, and lower right) as water discharge. 

Sediment loads from the tributaries and the 

estimated ungaged loads generally exceeded the 

contribution of sediments from the Illinois River. 

Illinois River loads were greater than these other 

sources during those periods when both discharges 

and loads were relatively small (late summer 

through early winter). Suspended sediment 

discharged from La Grange Pool generally 

followed the same patterns as input sediment 

loads and water discharge, but during the periods 

of high tributary loading (May in 1995 and 1996; 

February in 1997) the sediment export peaks were 

much smaller in magnitude than the input peaks.

The pattern of sediment storage and export 

in La Grange Pool is clarified by examining the 

net flux (input - output) behavior in terms of 

metric tons per day and the net flux expressed 

as a percentage of the input (Figure 7; upper 

and lower, respectively). La Grange Pool stored 

sediment (inputs greater than output) during the 

major high flow, high load months of the year 

during all 3 yrs of the study. The periods of peak 

discharge and peak loads (May in 1995 and 1996; 

February in 1997) all have positive values for net 

flux. During these months, the pool stores from 

25% to 75% of the suspended sediment input. The 

height, or relative magnitude of the storage events 

exceeds the sum of all the negative events, which 

implies that La Grange Pool is, on the whole, 

trapping sediments over the course of a year. On 

the other hand, on a temporal basis, the pool is 

most often mobilizing and exporting sediments 

(negative net flux periods) and it is only during the 

few large loading periods that tip the scale toward 

net sediment storage.
10

Comparison of Pool 13 and La Grange Pool

Pool 13 and La Grange Pool sit on vastly 

different rivers, have different hydrological 

settings with respect to those rivers, and have 

very different watersheds. The relative influence 

of the mainstem river (the Mississippi or Illinois 

River) is the first distinction between these two 

pools. In Pool 13, the Mississippi River dominates 

both the hydrology of the pool and the sediment 

loading. In La Grange Pool, however, the Illinois 

River is a major contributor of both water and 

sediment but it does not dominate the budget. 

The Mississippi River at Pool 13 is a much larger 

river in terms of land area drained and average 

flow than the Illinois River at La Grange Pool. 

The Mississippi River at Pool 13 drains over three 

times the land area than does the Illinois River 

at La Grange Pool. For the period of record, the 

mean daily flow in the Mississippi River is twice 

that in the Illinois River. The second distinction 

lies in the differences in sediment delivery by 

these rivers. Whereas the Mississippi River drains 

more land and has greater flows, its sediment 

supply to Pool 13 is considerably less than what 

the Illinois River supplies to La Grange Pool. 

The sediment export rate (calculated on an areal 

basis) for the watershed above Pool 13 is less than 

one-fourth the rate observed for the La Grange 

Pool watershed. The difference in sediment export 

rates are understandable given that the La Grange 

Pool watershed sits in one of the most fertile 

agricultural basins in the world; in contrast, much 

of the Pool 13 watershed is dominated by secondgrowth hardwood and coniferous forest (Table 5).

Figure 6. La Grange Pool monthly water (left) and suspended sediment budgets (right) for the 1995 (upper), 1996 (middle), and 1997 (lower) 

water years. “I” refers to input to La Grange Pool and “O” refers to outputs.

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

1995

1996

1997

1995

1996

1997

100000

80000

60000

40000

20000

0

100000

80000

60000

40000

20000

0

100000

80000

60000

40000

20000

0

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O 

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

I O I O I O I O I O I O I O I O I O I O I O I O

Mean daily discharge, 

m3/sec

Suspended sediment load, metric tons/day

Month Month

Source Mainstem Tributary Ungaged

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
11

The most striking difference between these 

pools is the manner in which they store and 

export suspended sediments. Pool 13 exported 

sediments during high flow-high load periods 

and stored them during the remainder of the year 

while La Grange Pool exhibited the opposite. In 

La Grange Pool, sediments are trapped during 

high flow-high load periods of the year and 

exported the rest of the time. The explanation 

for this striking difference in behavior may 

lie in the considerable difference between the 

morphometries of these two pools. Pool 13 

can be characterized as having a very riverine 

section for approximately 24 km; a transition 

zone, which is a more braided channel area, for 

the next 21 km; and a wide, open, and relatively 

shallow (1.0–1.5 m, other than the main channel) 

impounded area for the remaining 10.5 km. In 

contrast, La Grange Pool is essentially riverine for 

its entire length (124.7 km) and has an extensive 

levee system.

In Pool 13, the open area, sufficiently shallow 

to allow wind-generated waves to resuspend 

sediment and be subject to advective currents, 

may allow for the net export of suspended 

sediments during high flow-high load periods of 

the year. Periods of high flow will be associated 

with relatively higher current velocities both in 

the main channel and across the impounded area 

(Hendrickson, personal communication). The 

spring high-flow period is also associated with 

the passage of relatively frequent weather fronts 

that lead to the higher water inputs and may 

generate wind conditions that act to resuspend 

previously deposited sediments in the impounded 

area. The combination of resuspension and higher 

advective current velocities may be acting to 

allow the net export of suspended sediments. 

During the remainder of the year, when flows are 

lower, current velocities are reduced across the 

impounded area. Lower current velocities should 

result in less sediment being transported out of 

the system and could result in the net trapping of 

sediments.

In La Grange Pool, during high flow-high 

load periods of the year, the river may spread out 

onto what floodplain is still accessible (inside 

the levees) and allow material to settle out of 

suspension, thereby trapping sediments during 

these periods. During the remainder of the year 

when flows are lower in magnitude, the river 

may act as a more efficient conduit (flow and 

suspended sediment remain in the channel) for 

water and suspended material and result in a net 

export of suspended sediment.

Conclusion

The present study of the suspended sediment 

budgets of two navigation pools indicates that 

even more than 60 yrs after the construction of 

locks and dams to regulate these two rivers, these 

pools are still strikingly dynamic in the manner in 

which they process suspended sediments. Rather 

than being simple sediment sinks, net sediment 

exporters, or in some sort of equilibrium with 

their sediment loads, these pools exhibit all of 

these conditions over the course of a given year. 

O D F A J A O D F A J A O D F A J A 

C E E P U U C E E P U U C E E P U U

T C B R N G T C B R N G T C B R N G 

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 4 4 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7

 Month and year

75000

60000

45000

30000

15000

0

Suspended sediments, metric tons/day

-15000

O D F A J A O D F A J A O D F A J A 

C E E P U U C E E P U U C E E P U U

T C B R N G T C B R N G T C B R N G 

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 4 4 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7

 Month and year

100

50

0

-50

-100

-150

-200

-250

-300

Percent of Input

A

B

Figure 7. La Grange Pool suspended sediment balance (sum of 

inputs minus output) expressed as: (A) the metric tons per day of 

sediment storage (positive values, inputs exceed output) and export 

(negative values, outputs exceed inputs); (B) the percentage of the 

input sediment load that is stored or exported.
12

Not only does the mode of processing suspended 

sediments change in response to changes in 

hydrology, but the processes are completely 

different between the two pools.

Acknowledgments

This study was a cooperative effort between 

the U.S. Geological Survey Biological Division’s 

Upper Midwest Environmental Sciences Center, 

the U. S. Geological Survey Water Resources 

Division’s Water Districts of Wisconsin, Illinois, 

and Iowa, and the States of Wisconsin, Illinois, 

and Iowa.

References

Buchanon, T. J. and W. P. Somers. 1969. 

Discharge measurements at gaging stations. USGS 

Techniques of Water Resources Investigations 

Book 3, Chapter A8. 65 pp.

Demissie, M., R. Xia, L. Keefer, and N. G. 

Bhowmik. 2003. Sediment budget of the Illinois 

River. International Journal of Sediment Research 

18(2):305–313.

Fremling, C. R. and T. O. Claflin. 1984. 

Ecological history of the Upper Mississippi 

River. In J. G. Wiener, R. A. Anderson, and D. 

R. McConville, editors. Contaminants in the 

Upper Mississippi River, Proceedings of the 15th 

Annual Meeting of the Mississippi River Research 

Consortium. 

Gaugush, R. F. and D. B. Wilcox. 1994. 

Planning document: Investigate sediment 

transport/deposition and predict future 

configuration of UMRS channels and floodplain. 

National Biological Survey, Environmental 

Management Technical Center, Onalaska, 

Wisconsin, December 1994. LTRMP 94-P004. 

9 pp. + Appendixes A–E.

Great River Environmental Action Team. 

1980. GREAT I Study of the Upper Mississippi 

River, Volume 4, Technical Appendix F: Water 

Quality, Technical Appendix F: Sediment and 

Erosion. Great River Environmental Action Team, 

St. Paul, Minnesota.

Guy, H. P. and V. W. Norman. 1982. Field 

methods for measurement of fluvial sediment. 

USGS Techniques of Water Resources 

Investigations Book 3, Chapter C2. 59 pp.

Knox, J. C. 2000. Chapter 5. Geomorphic 

analysis. Pages 42–150 in J. B. Bradley, editor. 

Final report: Upper Mississippi River and Illinois 

Waterway Cumulative Effects Study, Volume 1: 

Geomorphic Assessment.

May, J. E., J. G. Gorman, R. D. Goodrich, 

M. W. Bobber, and V. E. Miller. 1996. Water 

resources data, Iowa, water year 1995. U.S. 

Geological Survey, Water Resources Division, 

Iowa City, Iowa. USGS-WRD-IA-95-1.

May, J. E., J. G. Gorman, R. D. Goodrich, 

M. W. Bobber, and V. E. Miller. 1997. Water 

resources data, Iowa, water year 1996. U.S. 

Geological Survey, Water Resources Division, 

Iowa City, Iowa. USGS-WRD-IA-96-1.

May, J. E., J. G. Gorman, R. D. Goodrich, 

M. W. Bobber, and V. E. Miller. 1998. Water 

resources data, Iowa, water year 1998. U.S. 

Geological Survey, Water Resources Division, 

Iowa City, Iowa. USGS-WRD-IA-97-1.

Nakato, T. 2000. Chapter 6. Sediment budget. 

Pages 151–172 in J. B. Bradley, editor. Final 

report: Upper Mississippi River and Illinois 

Waterway Cumulative Effects Study, Volume 1: 

Geomorphic Assessment.

Sparks, R. E. 1984. The role of contaminants 

in the decline of the Illinois River: Implications 

for the Upper Mississippi. Pages 25–66 in J. G. 

Wiener, R. A. Anderson, and D. R. McConville, 

editors. Contaminants in the Upper Mississippi 

River, Proceedings of the 15th Annual Meeting of 

the Mississippi River Research Consortium. 

U.S. Army Corps of Engineers, Rock Island 

District. 1980. Upper Mississippi River Basin, 

Mississippi River Basin, Nine Foot Channel 

Navigation Project, Reservoir Regulation Manual, 

Appendix 13, Lock and Dam 13.

U.S. Army Corps of Engineers, Rock Island 

District. 1986. Upper Mississippi River Basin, 
13

Illinois Waterway, Nine Foot Channel Navigation 

Project, Reservoir Regulation Manual, Appendix 

7, La Grange Lock and Dam.

U.S. Fish and Wildlife Service. 1992. 

Operating plan for the Upper Mississippi River 

System Long Term Resource Monitoring 

Program. Environmental Management Technical 

Center, Onalaska, Wisconsin. Revised September 

1993. EMTC 91-P002. 179 pp. (NTIS PB94-

160199).

Wicker, T. L., J. K. LaTour, and J. C. Miller. 

1996. Water resources data—Illinois, water 

year 1995. Volume 2. Illinois River Basin. U.S. 

Geological Survey, Water Resource Division, 

Urbana, Illinois. USGS-WRD-IL-95-2.

Wicker, T. L., J. K. LaTour, and J. C. Miller. 

1997. Water resources data—Illinois, water 

year 1996. Volume 2. Illinois River Basin. U.S. 

Geological Survey, Water Resource Division, 

Urbana, Illinois. USGS-WRD-IL-96-2.

Wicker, T. L., J. K. LaTour, and J. C. Maurer. 

1998. Water resources data—Illinois, water year 

1997. Volume 2. Illinois River Basin. U.S. Geological 

Survey, Water Resource Division, Urbana, Illinois. 

USGS-WRD-IL-97-2.
A-1

Appendix A

Summary Water and Suspended Sediment Data for Pool 13

Table A-1. Pool 13 water budget (unless otherwise indicated values are m3/sec) 

Water year

Mississippi 

(above Pool 13)

River Total

 gaged

 input

Total gaged

tributary 

inputa

Gaged export

coefficient

 (m3/sec/km2)b

Ungaged 

estimatec

Apple Plum Maquoketa Elk 

1995 1,636.7 5.8 7.0 32.4 1.4 1,683.3 46.6 0.0085 23.6 1996 1,779.0 5.7 7.2 25.8 1.1 1,818.8 39.7 0.0072 20.0 1997 1,755.1 4.1 4.7 30.5 1.1 1,795.5 40.4 0.0073 20.2 

aSum of the discharge from the Apple, Plum, Maquoketa, and Elk Rivers bGaged export coefficient = (total gaged triputary input)/(watershed area of gaged tributaries [5,514 km2])cUngaged estimate = (ungaged watershed area [2,772 km2]) x (gaged export coefficient)dTotal input = total gaged input + ungaged estimate Table A-2. Pool 13 suspended sediment budget (unless otherwise indicated values are metric tons/day)

Water year

Mississippi 

(above Pool 13)

River Total

 gaged 

input

Total gaged

tributary inputa

Gaged export

coefficient

 (kg/km2/yr)b

Ungaged 

estimatec

Apple Plum Maquoketa Elk 

1995 6,526 146 155 1,058 18 7,903 1,377 91.2 692 1996 7,012 230 151 1,167 112 8,672 1,660 109.9 834 1997 7,076 119 169 2,075 61 9,500 2,363 156.4 1,187 

aSum of the load from the Apple, Plum, Maquoketa, and Elk RiversbGaged export coefficient = (total gaged tributary input)/(watershed area of gaged tributaries [5,514 km2])cUngaged estimate = (ungaged watershed area [2,772 km2]) x (gaged export coefficient)dTotal input = total gaged input + ungaged estimate 
B-1

Appendix B

Summary Water and Suspended Sediment Data for La Grange Pool

Table B-2. La Grange Pool suspended sediment budget (unless otherwise indicated values are metric tons/day)

Water year

Illinois (above 

La Grange Pool)

River Total 

gaged

 input

Total gaged

tributary 

inputa

Gaged export

coefficient 

 (kg/km2/yr)b

Ungaged 

estimatec

Lamoine Mackinaw Sangamon Spoon 

1995 3,017 1,761 1,536 3,061 3,438 12,813 9,796 151.8 3,299 1996 3,522 1,982 752 2,625 2,551 11,432 7,910 122.6 2,664 1997 4,685 901 364 1,266 1,792 9,008 4,323 67.0 1,456 

aSum of the load from the Lamoine, Mackinaw, Sangamon, and Spoon Rivers bGaged export coefficient = (total gaged triputary input)/(watershed area of gaged tributaries [23,555 km2])cUngaged estimate = (ungaged watershed area [7,932 km2]) x (gaged export coefficient)dTotal input = total gaged input + ungaged estimate Table B-1. La Grange Pool water budget (unless otherwise indicated values are m3/sec) 

Water year

Illinois (above 

La Grange Pool)

River Total 

gaged

 input

Total gaged

tributary 

inputa

Gaged export

coefficient 

 (m3/sec/km2)b

Ungaged 

estimatec

Lamoine Mackinaw Sangamon Spoon 

1995 482.4 43.8 30.5 132.6 49.7 739.0 256.5 0.0109 86.5 1996 409.2 30.6 11.8 87.9 28.8 568.3 159.1 0.0068 53.9 1997 439.7 20.4 12.0 61.6 29.3 563.0 123.3 0.0052 41.2 

aSum of the discharge from the Lamoine, Mackinaw, Sangamon, and Spoon Rivers bGaged export coefficient = (total gaged triputary input)/(watershed area of gaged tributaries [23,555 km2])cUngaged estimate = (ungaged watershed area [7,932 km2]) x (gaged export coefficient)dTotal input = total gaged input + ungaged estimate 
C-1

Appendix C

Monthly Summaries of Water and Suspended Sediment Data for Pool 13

Table C-1. Monthly means for discharge (ft3 sec-1) for the Mississippi River at Lock and Dam 13 at Bellevue, Iowa. U.S. Geological Survey station code 0541600.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 59,367.7 49,076.7 40,422.6 30,451.6 29,453.6 61,061.3 93,146.7 92,751.6 68,916.7 46,845.2 1996 69,593.5 73,436.7 38,967.7 36,774.2 42,379.3 65,619.4 111,273.3 107,767.7 889,96.7 59,012.9 1997 30,919.4 57,063.3 47,845.2 39,967.7 42,442.9 62,996.8 151,233.3 87,312.9 47,796.7 69,209.7 

Table C-2. Monthly means for sediment load (tons day-1) for the Mississippi River at Lock and Dam 13 at Bellevue, Iowa. U.S. Geological Survey station code 0541600

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 6689.0 2724.3 1355.0 1318.5 1408.4 6250.1 11757.3 17525.8 9653.3 5332.6 1996 9252.0 5839.7 588.3 508.6 866.3 4963.4 18022.6 15240.3 21788.7 9716.7 1997 3635.2 5356.3 1266.5 595.9 2140.3 7905.5 32403.3 16631.0 4809.0 9626.5 

Table C-3. Monthly means for discharge (ft3 sec-1) for the Apple River near Hanover, Illinois. U.S. Geological Survey station code 0541900.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 111.7 155.4 169.8 141.7 108.0 141.2 360.6 658.5 282.8 149.4 1996 83.8 125.9 82.9 178.7 455.9 80.4 94.1 443.6 587.0 142.7 1997 59.3 60.2 63.3 104.3 396.2 233.3 126.8 205.3 227.5 130.4 
C-2

Table C-4. Monthly means for sediment load (tons day-1) for the Apple River near Hanover, Illinois. U.S. Geological Survey station code 0541900.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 15.7 28.6 11.8 11.9 4.8 10.6 103.5 1596.4 72.8 22.4 1996 14.3 10.2 2.4 27.5 756.7 8.2 13.2 1393.1 782.9 31.4 1997 5.5 5.3 2.9 6.0 837.6 385.8 14.9 28.1 298.8 42.6 

Table C-5. Monthly means for discharge (ft3 sec-1) for the Elk River near Altmont, Iowa. U.S. Geological Survey station code 05420300.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 20.2 35.9 34.8 27.6 34.5 40.0 84.4 121.6 53.7 55.3 1996 20.1 26.2 16.6 16.8 24.3 14.5 17.6 143.7 94.1 36.1 1997 29.7 21.2 24.3 23.8 178. 8 42.5 31.9 39.8 31.2 23.9 

Table C-6. Monthly means for sediment load (tons day-1) for the Elk River near Altmont, Iowa. U.S. Geological Survey station code 05420300.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 0.6 20.3 1.3 1.3 2.9 1.8 68.5 102.2 6.1 5.1 1996 1.2 3.0 1.0 3.4 26.3 0.5 0.5 1093. 5 327.4 5.5 1997 44.5 1.2 1.0 15.7 694.3 58.6 2.6 10.0 18.3 11.1 
C-3

Table C-7. Monthly means for discharge (ft3 sec-1) for the Maquoketa River near Maquoketa, Iowa. U.S. Geological Survey station code 05418500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 913.4 795.2 892.3 637.8 747.1 929.5 2046.5 2698.7 1699.0 969.8 1996 514.4 647.3 451.4 431.8 981.4 808.9 576.4 1826.6 2522.0 1080.2 1997 499.2 587.0 558.0 538.7 2721.1 1837.7 1020.3 1529.3 1808.7 891.6 

Table C-8. Monthly means for sediment load (tons day-1) for the Maquoketa River near Maquoketa, Iowa. U.S. Geological Survey station code 05418500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 255.5 288.4 258.4 102.0 174.7 520.3 2361.8 5494.9 1308.1 978.2 1996 141.8 179.9 41.8 37.7 1519.1 467.3 142.4 4408.1 7552.3 625.3 1997 153.7 94.6 60.2 47.6 13985.4 4389.9 196.6 1183.6 7489.5 648.9 

Table C-9. Monthly means for discharge (ft3 sec-1) for the Plum River at Savanna, Illinois. U.S. Geological Survey station code 05420100.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 92.1 192.5 179.7 197.3 151.0 151.6 422.8 863.8 343.4 169.1 1996 91.6 179.9 130.5 176.5 317.4 113.5 145.0 731.5 750.4 209.9 1997 81.2 82.6 71.1 88.5 658.3 332.5 133.4 189.9 166.5 90.2 
C-4

Table C-12. Monthly means for sediment load (tons day-1) for the Mississippi River at Clinton, Iowa. U.S. Geological Survey station code 05420500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 5847.7 3788.3 2506.1 877.0 663.5 8631.9 28520.0 38171.0 11847.7 5705.2 1996 5602.9 6552.8 316.5 379.4 239.7 8239.0 32808.0 34187.1 29060.0 9503.5 1997 5808.1 4543.3 1330.1 1097.1 3805.7 5955.5 43623.3 23251.0 5271.7 8224.2 

Table C-11. Monthly means for discharge (ft3 sec-1) for the Mississippi River at Clinton, Iowa. U.S. Geological Survey station code 05420500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 59464.5 52313.3 44693.5 36187.1 33210.7 61774.2 101706.7 103551.6 70260.0 51045.2 1996 73333.3 42051.6 36935.5 39817.2 61574.2 114783.3 125377.4 95753.3 61438.7 35951.6 1997 57226.7 46667.7 41774.2 49382.1 65722.6 175856.7 96429.0 52006.7 65951.6 60974.2 

Table C-10. Monthly means for sediment load (tons day-1) for the Plum River at Savanna, Illinois. U.S. Geological Survey station code 05420100.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 11.0 64.7 51.4 49.6 23.7 20.0 437.4 1054.1 154.8 89.8 1996 23.5 45.2 21.2 65.4 103.4 34.0 30.1 1252.7 201.2 149.4 1997 28.2 25.9 8.8 15.6 1223.7 560.3 23.4 104.3 270.8 36.5 
D-1

Appendix D

Monthly Summaries of Water and Suspended Sediment Data for La Grange Pool

Table D-1. Monthly means for discharge (ft3 sec-1) for the Illinois River at Pekin, Illinois. U.S. Geological Survey station code 05563800.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 4990.0 15441.7 19468.7 21843.9 13232.5 16579.7 28096.7 31603.2 27703.3 10024.2 1996 6112.6 13369.7 7577.7 7077.1 6898.6 8330.0 11310.3 21001.0 40450.0 25427.4 1997 6232.6 8257.0 12245.2 10767.1 26341.1 43103.2 18676.0 13674.2 21307.7 9710.3 

Table D-2. Monthly means for sediment load (tons day-1) for the Illinois River at Pekin, Illinois. U.S. Geological Survey station code 05563800.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 1043.8 6407.0 3211.3 3300.0 2012.1 3710.0 5333.3 4884.5 4052.3 3105.8 1996 1356.1 3958.0 2278.5 2241.9 672.1 1531.5 3703.1 9367.3 5581.5 11684.9 1997 1116.3 1308.8 2453.9 1061.4 22108.0 9414.5 6910.1 4797.0 6387.9 2300.5 

Table D-3. Monthly means for discharge (ft3 sec-1) for the La Moine River at Ripley, Illinois. U.S. Geological Survey station code 05585000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 24.8 198.3 510.7 806.9 669.2 623.7 2988.1 9257.5 1847.2 723.2 1996 121.2 321.2 107.5 377.9 511.8 420.3 394.5 7027.8 2402.0 918.1 1997 35.5 48.7 48.2 56.6 2187.4 1727.2 1379.0 1205.3 1663.7 210.4 
D-2

Table D-4. Monthly means for sediment load (tons day-1) for the La Moine River at Ripley, Illinois. U.S. Geological Survey station code 05585000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 4.1 65.7 740.0 1091.7 769.2 280.0 4843.8 11518.0 2300.1 495.0 1996 66.2 157.7 14.3 179.0 443.5 137.5 211.0 20613.4 3110.4 875.1 1997 3.6 3.7 2.5 8.3 4112.5 1704.9 1287.1 1621.7 3256.4 99.3 

Table D-5. Monthly means for discharge (ft3 sec-1) for the Mackinaw River near Green Valley, Illinois. U.S. Geological Survey station code 05568500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 50.2 119.4 446.1 1208.9 359.9 909.3 2379.8 5494.7 1169.0 405.2 1996 73.6 201.1 102.4 150.0 108.2 185.5 254.9 2084.4 1350.9 262.9 1997 49.0 60.4 88.4 148.9 1390.3 1413.9 755.1 370.5 468.5 152.5 

Table D-6. Monthly means for sediment load (tons day-1) for the Mackinaw River near Green Valley, Illinois. U.S. Geological Survey station code 05568500.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 4.0 11.2 152.9 1228.4 30.5 595.3 5249.1 11722.0 873.5 211.2 1996 18.2 32.1 13.3 27.1 14.8 24.7 51.1 8362.5 1131.1 81.8 1997 4.1 7.9 8.0 19.9 3388.7 1108.7 191.8 51.7 207.5 38.6 
D-3

Table D-7. Monthly means for discharge (ft3 sec-1) for the Sangamon River near Oakford, Illinois. U.S. Geological Survey station code 05583000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 389.3 974.9 1937.6 5913.9 2711.1 5951.0 4799.3 20541.6 8033.3 2290.3 1996 437.9 700.8 606.0 1036.9 843.9 1575.8 2272.3 17811.3 9188.3 1475.8 1997 323.6 406.8 438.3 931.1 3883.9 8208.1 2383.7 2444.8 4300.7 1515.6 

Table D-8. Monthly means for sediment load (tons day-1) for the Sangamon River near Oakford, Illinois. U.S. Geological Survey station code 05583000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 40.4 98.4 510.4 4709.3 448.9 4291.4 2627.2 21172.2 3896.2 1391.2 1996 67.8 145.6 28.7 244.6 113.6 451.0 1385.9 25246.6 5933.6 510.7 1997 16.3 9.4 5.8 97.8 4727.7 5879.7 589.4 1265.5 3172.6 806.9 

Table D-9. Monthly means for discharge (ft3 sec-1) for the Spoon River at Seville, Illinois. U.S. Geological Survey station code 05570000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 56.4 725.1 1138.5 978.5 1072.5 1097.9 3136.8 8015.5 2548.3 1477.5 1996 161.6 457.9 246.7 373.6 520.5 405.7 371.1 4214.3 3936.7 1058.3 1997 92.4 144.9 131.0 170.4 4231.6 2554.0 1548.4 908.7 1117.7 348.4 
D-4

Table D-10. Monthly means for sediment load (tons day-1) for the Spoon River at Seville, Illinois. U.S. Geological Survey station code 05570000.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 8.8 622.8 1254.8 751.6 719.0 572.8 8192.9 24984.4 3357.3 3958.6 1996 66.4 195.4 97.1 103.6 202.3 180.7 164.9 18705.2 9545.0 4006.3 1997 12.2 23.0 10.1 30.8 14240.7 4326.4 1285.9 401.4 1828.3 237.3 

Table D-11. Monthly means for discharge (ft3 sec-1) for the Illinois River at Valley City, Illinois. U.S. Geological Survey station code 05586100.

Water year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 1995 5743.2 17847.3 25925.8 29041.9 25167.9 28283.9 39610.0 69683.9 68616.7 19912.9 1996 7301.3 15500.0 8478.4 9311.0 9459.0 11991.0 14570.3 50274.2 69130.0 31719.4 1997 8632.6 10684.7 13184.5 12241.9 27975.0 67580.6 29200.0 19545.2 29403.3 17090.3 

Table D-12. Monthly means for sediment load (tons day-1) for the Illinois River at Valley City, Illinois. U.S. Geological Survey station code 05586100.

Water 

year Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

1995 982.8 14240.7 16855.2 19617.7 6972.9 15143.9 28579.0 26898.7 23544.3 17379.7 1996 1464.3 11247.3 3167.8 3620.2 2342.9 5758.4 11751.9 73178.1 21651.7 27817.4 1997 1274.2 2138.9 4632.4 3379.5 40895.7 24109.2 15329.3 8282.2 23738.6 5828.0 
REPORT DOCUMENTATION PAGE Form Approved

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

September 2004

3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE A suspended sediment budget for Pool 13 and La Grange Pool of the Upper Mississippi River 

System

5. FUNDING NUMBERS

6. AUTHOR(S) Robert F. Gaugush

7. PERFORMING ORGANIZATION NAME AND ADDRESS

Upper Midwest Environmental Science Center, 2360 Fanta Reed Road, La Crosse, Wisconsin 54603

8. PERFORMING ORGANIZATION

 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

 U.S. Geological Survey 

 Upper Midwest Environmental Sciences Center

 2630 Fanta Reed Road

 La Crosse, Wisconsin, 54603

10. SPONSORING/MONITORING

 AGENCY REPORT NUMBER

2004-T004

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Release unlimited. Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 (1-

800-553-6847 or 703-487-4650). Also available to registered users from the Defense Technical Information Center, Attn: Help 

Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or 703-767-9050).

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words) 

The suspended sediment budget for Pool 13 of the Mississippi River and La Grange Pool of the Illinois River was examined over a 3-yr period (October 1995 through 

September 1997). Pool 13 output was betwee 

by those delivered by the Mississippi River (76%, 74%, and 66% in the 1995, 1996, and 1997 water years, respectively). Pool 13 exhibited sediment export (output greater 

than input) in 1995, a balance in 1996, and marked sediment trapping (output less than input) in 1997. Within the three study years, Pool 13 received its highest water and 

sediment loads during spring (March through May) and this period was marked by sediment export. Suspended sediment loads were trapped during the remainder of the year. 

La Grange Pool output was between 3.71 and 5.04 million t of suspended sediment annually during the 1995–97 water years. The Illinois River accounted for less than 50% of 

the suspended sediment load to the pool (19%, 25%, and 45% in the 1995, 1996, and 1997 water years, respectively. La Grange Pool exhibited considerable sediment trapping 

in 1995 whereas the 1996 and 1997 water years were much closer to a balance wherein output was within 5% of input. Generally, La Grange Pool received its largest water and 

sediment loads during the late spring–early summer period (April through June), but in 1997 the late winter loads predominated. 

14. SUBJECT TERMS

La Grange, Mississippi River, Pool 13, river, sediment budget, sediment load

15. NUMBER OF PAGES

 13 pp. + Appendixes A–D

16. PRICE CODE

17. SECURITY CLASSIFICATION

 OF REPORT

Unclassified

18. SECURITY CLASSIFICATION

 OF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATION

 OF ABSTRACT

Unclassified

20. LIMITATION OF ABSTRACT
The Long Term Resource Monitoring Program (LTRMP) for the Upper Mississippi River 

System was authorized under the Water Resources Development Act of 1986 as 

an element of the Environmental Management Program. The mission of the LTRMP 

is to provide river managers with information for maintaining the Upper Mississippi 

River System as a sustainable large river ecosystem given its multiple-use character. 

The LTRMP is a cooperative effort by the U.S. Geological Survey, the U.S. Army Corps 

of Engineers, and the States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin.