The Response of Suspended Sediment, 

Turbidity, and Velocity to Historical 

Alterations of the Missouri River

Prepared in cooperation with the U.S. Environmental Protection Agency

U.S. Department of the Interior

U.S. Geological Survey

Circular 1301

Prepared in cooperation with the U.S. Environmental Protection Agency

The Response of Suspended Sediment, 

Turbidity, and Velocity to Historical 

Alterations of the Missouri River
Front Cover. Derived from Karl Bodmer’s water color and pencil rendering of the unengineered Missouri River in 1833 near St. Joseph, 

Missouri (original used with permission from Josyln Art Museum, Omaha, Nebraska).

Back Cover. Left side, top: Log mat placed on top of graded bank to stabilize an outer bend of the Missouri River in Nebraska, 1934 

(photograph courtesy of the U.S. Army Corps of Engineers).

Left side, middle: Lumber mattress constructed for bank stabilization on the Missouri River near Indian Cave Bend in Nebraska, 1937 

(photograph courtesy of the U.S. Army Corps of Engineers).

Left side, bottom: Construction of rock wing dike on the Missouri River in Nebraska, 1934 (photograph courtesy of the U.S. Army Corps 

of Engineers).

Right side, inset: Typical rock wing dikes in modern Missouri River near Bonnott’s Mill, Missouri (photograph from the U.S. Geological 

Survey).

1804

1804

1843

1879

1900

1907

1929–1932

1973–2002

DATA COLLECTION

William Clark observes approximately one-sixteenth of the volume of a Missouri River water sample is 

suspended sediment.

Meriwether Lewis evaporates one pint of Missouri River water and gets 81 grains of evaporite.

Edward Harris on the Audubon Expedition observes that about one-tenth of the volume of a Missouri River 

water sample collected near present day Gavins Point Dam is suspended sediment.

U.S. Army Corps of Engineers collect daily suspended-sediment samples from February 1 to October 1 

(Keown and others, 1981).

William Teichmann collects daily grab samples near St. Charles, Missouri, from January 24 to October 10.

Richard Dole (U.S. Geological Survey) collects 10-day composite samples from October 4, 1906, to October 

14, 1907, at Omaha, Nebraska, and St. Charles, Missouri (Dole, 1909).

U.S. Army Corps of Engineers collects daily suspended-sediment samples from May 8, 1929, to July 22, 1932, 

at eight sites on the Missouri River. Only monthly data were published (Chief of Engineers, 1935).

U.S. Geological Survey collects samples on approximately monthly intervals at Hermann, Missouri, and 

Omaha, Nebraska.

1952–1963

1838–1929

1930–1936

CONSTRUCTION

Site specific bank stabilization and channel dredging projects completed. 

Effects on suspended sediment and turbidity were minor.

Construction of 6 feet deep by 200 feet wide navigation channel with large-scale bank 

stabilization.

Fort Peck Dam closed in Montana.

Construction of 9 feet deep by 300 feet wide navigation channel with large-scale bank 

stabilization.

Closure of five more large dams in North Dakota and South Dakota.

1937

1950–1962

Timeline of Construction and Suspended Sediment and Turbidity 

Data Collection on the Missouri River
The Response of Suspended Sediment, 

Turbidity, and Velocity to Historical 

Alterations of the Missouri River

By Dale W. Blevins

Circular 1301

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the 

U.S. Environmental Protection Agency
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2006

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information on the USGS–the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. 

Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Blevins, D.W., 2006, The response of suspended sediment, turbidity, and velocity to historical alterations of the Missouri River: U.S. Geological Survey Circular 1301, 8 p.

Library of Congress Cataloging-in-Publication Data

Blevins, Dale W.

 The response of suspended sediment, turbidity, and velocity to historical alterations of the Missouri River / by Dale 

W. Blevins.

 p. cm. -- (Circular ; 1301)

 “Prepared in cooperation with the U.S. Environmental Protection Agency.”

 Includes bibliographical references.

 1. Sediment transport--Missouri River. 2. River engineering--Environmental aspects--Missouri River Watershed. I. 

Title. 

 TC425.M7B583 2007

 627’.1220978--dc22

 2007001224 

ISBN 1-411-31256-2
iii

Contents

Historical Measurements.............................................................................................................................1

Suspended Sediment ...........................................................................................................................2

Turbidity ..................................................................................................................................................5

Comparison with Modern Measurements.................................................................................................5

River Velocities...............................................................................................................................................7

Conclusions and Implications......................................................................................................................7

References......................................................................................................................................................8

Figures

1. Map showing Missouri River Basin with location of historic and modern suspendedsediment, turbidity, and velocity sites on the Missouri River................................................2

2–4. Boxplots showing:

 2. Summary of suspended-sediment concentrations before dams, large-scale 

bank stabilization, and watershed development..............................................................3

 3. Summary of monthly suspended-sediment concentrations in the Missouri River....4

 4. Turbidity in 10-day composite of grab samples collected in the 1907 water year 

and turbidity in depth-integrated samples collected from 1973 through 2001 ............5

5–8. Graphs showing:

 5. Turbidity with suspended-sediment concentration at Kansas City, Kansas, in 

the 1907 water year...............................................................................................................6

 6. Average annual turbidity at the Kansas City, Kansas, Water Plant, 1918 through 

1954 with best-fit fourth-order polynomial trend line ......................................................6

 7. Relation between mean water velocity and discharge in the Missouri River at

Waverly, Missouri, as recorded in U.S. Geological Survey discharge measurement notes ..............................................................................................................................8

 8. Relation between maximum water velocity and discharge in the Missouri River

at Waverly, Missouri, as recorded in U.S. Geological Survey discharge measurement notes ..............................................................................................................................8
iv

Conversion Factors and Datum

Water year: The 12-month period October 1 through September 30. The water year is 

designated by the calendar year in which it ends.

For suspended-sediment samples with concentrations less than 10,000 milligrams per liter, 

the density correction to convert to parts per million is less than 1 percent, which is less 

than the errors of sample collection and laboratory analysis. Therefore, analytical results in 

both units are comparable and no conversions of historical analyses from parts per million to 

milligrams per liter are necessary except for three large concentrations reported by William 

Clark, Meriwether Lewis, and Edward Harris, which are computed in milligrams per liter for 

comparison with modern measurements. 

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Volume

ounce, fluid (fl. oz) 0.02957 liter (L)

pint (pt) 0.4732 liter (L)

Flow rate

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

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)
The heavy sediment load and large amounts of floating debris generated by the constantly caving banks of the

Missouri River was documented in the first written description of the river by Father Jacques Marquette in 1673 as he

approached the mouth of the Missouri River from the upper

Mississippi River:

“[We]” heard the noise of a rapid, into which 

we were about to run. I have seen nothing more 

dreadful. An accumulation of large and entire trees, 

branches, and floating islands, was issuing from the 

mouth of the river Pekitanoui (Missouri River), with 

such impetuosity that we could not without great 

danger risk passing through it. So great was its agitation that the water was so very muddy, and could 

not become clear.”

However, large changes in suspended sediment and

turbidity in the lower Missouri River below Gavins Point

Dam (fig. 1) have occurred in response to extensive structural

changes that have been imposed on the Missouri River and

its watershed during the last two centuries. Efforts to shape

the channel, remove snags and sawyers, dredge shallows, and

stabilize banks for navigation began as early as 1838 (http://

www.lewis-clark.org/ri_mo-snagboats.htm, Chittenden, 1903).

However, bank stabilization efforts were sporadic and scattered in comparison to large scale changes that occurred after

1929. In the early 1930s the numerous small channels were

combined into a single-fixed channel with 4,745 stone and

wood-pile dikes, 3,371 dike extensions, streambank protection

works on concave banks, man-made cutoffs, the closing of

chutes with dikes, the removal of snags, and dredging (Keown

and others, 1981). The resulting navigation channel was 6-ft

(feet) deep by 200-ft wide and was expanded to 9 by 300 ft

in the 1950s and early 1960s. Construction of six dams was

started in 1933 and their reservoirs were filled by 1967. Three

of these reservoirs are among the five largest in the United

States. Nearly one-third of the Missouri River is now submerged below these massive reservoirs. Since 1967, hydrologic changes have been relatively minor.

In the early 1970s, the U.S. Geological Survey (USGS)

began the long-term, systematic collection of suspendedsediment and water-quality data that continues to the present

(2006). Because changes in the channel configuration and

hydrologic character of the river have been small compared to

the changes before 1973, all samples collected after that time

are referred to in this report as modern samples. These modern

samples compose a large data set that are compared to samples

collected before the pervasive hydrologic and channel-stabilizing changes that began in the early 1930s and to the qualitative

and semiquantitative observations of the explorers in the early

nineteenth century.

Historical Measurements

The largest change in the water quality of the lower Missouri River likely is the decrease of suspended sediment and

turbidity, which are of importance to ecological communities,

drinking-water utilities, and many other users of the modern

river. Characterization of predevelopment suspended-sediment and turbidity concentrations is important to quantify the

changes that have occurred. Unfortunately, the rare observations of suspended sediment and turbidity in the Missouri

River before 1879 are semiquantitative to descriptive or

anecdotal.

The Response of Suspended Sediment, Turbidity, and 

Velocity to Historical Alterations of the Missouri River

By Dale W. Blevins

Ceremonies in Kansas City, Missouri, commemorating the opening 

of the 6-foot channel between Kansas City and St. Louis, Missouri, 

1932. (Photograph used with permission from the Missouri Valley 

Special Collections, Kansas City Public Library, Kansas City, 

Missouri.)
Suspended Sediment

Meriwether Lewis and William Clark made the first

semiquantitative measurements of suspended sediment in 1804

in two ways:

 “The water we Drink, or the Common water of the 

missourie [sic] at this time, contains half a Comn 

[sic] Wine Glass of ooze or mud to every pint”

(Moulton, 1986) (Observed June 21, 1804, by William Clark at a high, but within-bank, stage near

present-day Waverly, Missouri)

“Precipitate of one pint of Missouri water weight 

80:65 grs (grains) [principally common Clay.]”

[Reported by Meriwether Lewis (Moulton, 1986)].

(Collected in 1804 somewhere between present-day

Bismarck, North Dakota, and the mouth of the Missouri River.)

Edward Harris in an expedition with John J. Audubon

made the following observation (McDermott, 1951):

“No otters, beaver, muskrats, or even minks are 

found in about the turbid waters of this all-mighty 

stream, the water of which looks more like a hog 

puddle than anything else I can compare it to. About 

one-tenth of its bulk forms a despite (deposit) in half 

an hour.” (Observed May 24, 1843, at a high, but

within-bank, stage near present-day Gavins Point

Dam)

Assuming the porosity of settled sediment was 40

percent, the specific gravity of suspended sediment was 2.6

(Chief of Engineers, 1935), and the size of William Clark’s

“wineglass” was 2 fl. oz (fluid ounces; Husted, 1957) the computed sediment concentrations for these observations are:

98,000 mg/L (milligrams per liter; settleable sediment)

(92,000 parts per million) [1 fl. oz

pint x 30 fl. oz

cm3

x (1 – 0.40

porosity) x 2,600 cm3

mg x 2.1 pints

liter ],

11,000 mg/L [Total solids. To estimate suspended-sediment concentration, approximately 400 mg/L dissolved

solids is subtracted (Dole, 1909), which results in 10,600

mg/L (10,500 parts per million), (865 grains/pint x 68 

grain

mg x 2.1 pints

liter )], and

160,000 mg/L (Settleable sediment) (150,000 parts per

million) [(100 cm3 sediment/liter) x (1 – 0.40 porosity) x

2,600 cm3

mg ].

1.

2.

3.

45°

100°

105° 110°

95°

40°

0 100 200 MILES

0 100 200 KILOMETERS

EXPLANATION

Suspended-sediment and turbidity 

 sampling sites

Velocity measuring site

Missouri River Basin CANADA

MONTANA

SOUTH

DAKOTA

NORTH

DAKOTA

MINNESOTA

COLORADO

IOWA

WYOMING

MISSOURI

NEBRASKA

KANSAS Hermann

Waverly

Kansas

City

St. Charles

Omaha

Bismarck

Gavins

Point

Dam

Garrison

Dam

Fort Randall Dam

Oahe Dam

Big Bend Dam

Fort Peck

Dam

RIVER

MISSOURI

Figure 1. Missouri River Basin with location of historic and modern suspended-sediment, turbidity, and velocity sites on the Missouri 

River.

 The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River
William Teichmann collected and analyzed daily grab

samples of total solids from the Missouri River 3 to 4 ft below

the water surface from a boat near St. Charles, Missouri,

from January 24 through October 10, 1900, (Leighton, 1907).

Because Teichmann’s analyses were of total solids, the dissolved-solids concentration, which averaged approximately

400 ppm (parts per million) before the reservoirs in 1907

(Dole, 1909), was subtracted from total-solids concentrations

to estimate suspended-solids concentrations. Teichmann’s

median of 1,600 ppm was undoubtedly greater than the annual

median because Teichmann did not collect samples from October 1, 1899, to January 23, 1900, when the Missouri River

was low and correspondingly less turbid. Teichmann’s largest

suspended-solids concentration of 4,200 ppm is only 3 to 40

percent of the three semiquantitative measurements recorded

by Lewis, Clark, and Audubon.

Grab samples were also collected daily from October 4,

1906, through October 14, 1907, (hereafter referred to as the

1907 water year), composited every 10 days, and analyzed

for suspended sediment, total dissolved solids, turbidity, and

several other constituents at five sites on the Missouri River

as part of a nationwide survey of stream-water quality coordinated and published by Richard Dole of the USGS (Dole

1909; fig. 2). Samples usually were collected in 4-ounce

bottles from bridges near the water surface. The median

suspended-sediment concentration of the 10-day composite

samples was 1,600 ppm at St. Charles, Missouri, and 1,550

ppm at Omaha, Nebraska. For the months corresponding to

Teichmann’s sampling period (January to October), Dole’s

1907 median concentration was 2,320 ppm compared to the

median of 10-day averages of Teichmann’s daily data in 1900

of 1,800 ppm. The annual maximum concentration in 1907

was 6,330 ppm at St. Charles (fig. 2) compared to 3,000 ppm

(again using 10-day averages) for 9 months during 1900. Suspended-sediment concentrations were greater in 1907 likely

because the 1907 and 1900 water years had the second largest

and fifteenth smallest annual discharges, respectively, in the

52-year period before substantial flow regulation between

1898 and 1950 (Stevens and Hardison, 1951). Despite these

differences, Teichmann’s and Dole’s data are much more

comparable than the two concentrations computed from the

sediment-settling observations of William Clark and Edward

Harris (measurements 1 and 3), which are more than 14 times

the highest concentration measured by either Dole or Teichmann. This large difference casts some doubt on the accuracy

of Clark and Harris’s sediment-settling observations. However,

both Clark’s and Harris’s observations were from instantaneous samples made near bankfull stages, whereas Dole’s

Figure 2. Summary of suspended-sediment concentrations before dams, large-scale bank stabilization, and watershed development 

(A) in 10-day composite samples collected at three locations on the lower Missouri River for water year 1907 (Dole, 1909) and (B) 

near St. Charles, Missouri, from February through October 1879 (median only), and January to October 1900 and 1907 [1907 data from 

Dole (1909); 1900 data modified from Leighton (1907) by subtracting 400 milligrams per liter dissolved solids from reported total-solids 

concentrations; 1879 data from Keown and others (1981)].

Historical Measurements 

1,800

2,320

1,600

SUSPENDED-SEDIMENT CONCENTRATION, IN PARTS PER MILLION

January to October 1900 and 1907

near St. Charles, Missouri

Daily samples 

1900

10-day average

concentrations

1900

10-day composite

samples

1907

1,600 1,710 1,550

0

2,000

4,000

6,000

8,000

10-day composite samples

 1907 water year 

Omaha,

Nebraska

Kansas City,

Missouri

St. Charles,

Missouri

A B

(229)

(26)

(25)

(36)

(38)

(36)

Mean daily 

suspended-sediment

concentration February 1 

through October 31, 1879 25th percentile

Minimum

Maximum

Number of samples

50th percentile 

 (Median and value)

75th percentile

1,550

(36)

EXPLANATION
largest concentration is a 10-day composite sample. The

instantaneous maximum during that 10-day period undoubtedly was much larger than 6,330 ppm.

The U.S. Army Corps of Engineers collected the first set

of daily suspended-sediment samples on the Missouri River at

St. Charles, Missouri, from February 1 to October 31, 1879,

(Keown and others, 1981). Samples were collected at middepth and 1 ft from the bottom at eight points equally distributed across the river. A physical description of the sampling

device was not included in the documentation. The average

daily discharge during this period was 83,000 ft3/s (cubic

feet per second), which is 5 percent less than the modern

average annual discharge at Hermann, Missouri (Hauck and

Nagel, 2002), just upstream. The average suspended-sediment

concentration during this 9-month period was 4,100 mg/L.

Despite the less than average discharge, this mean concentration is near the maximum concentration of daily samples collected by Teichman for nearly the same period in 1900 (fig. 2),

but substantially less than concentrations computed from the

observations of the early explorers.

Another set of suspended-sediment data were collected at

eight Missouri River sites by the U.S. Army Corps of Engineers (Chief of Engineers, 1935) from May 8, 1929, to July

22, 1932, before reservoir construction and just preceding and

during the initial construction of the first 6-ft deep by 200-ft

wide channel. At most sites sample concentrations were plotted against daily discharge to develop a sediment-discharge

curve that was used to estimate daily and monthly suspendedsediment concentrations. This method was enhanced at most

sites with the collection of hundreds of samples during 3

years. Also, samples were collected at equal-width increments

across the stream and at up to five different depths to develop

methods for collection of representative samples. Consequently, these data, while not all preceding the initial construction of the 6 by 200-ft channel, likely are more representative

and reliable than the grab samples collected by Teichmann

and Dole. Despite the monthly time step (daily maximums are

usually greater than 10-day or monthly-average maximums)

and the low discharges between July 1, 1929, and June 30,

1930, the annual maximum of monthly concentrations near

St. Charles (6,650 ppm) is larger than the daily maximum

reported by Teichmann for 1900 (4,200 ppm) and Dole’s 10-

day composites in 1907 (6,330 ppm; figs. 2 and 3). However,

the average suspended-sediment concentration in 1879 (4,100

ppm) would fall well within the upper quartile of monthly concentrations at St. Charles, Missouri, from 1929 to 1932. The

maximum instantaneous concentration in the 1929 to 1932

data was 12,440 ppm measured in a sample collected on June

4, 1929, at Kansas City, Missouri, at a discharge of 224,000

ft3/s (Chief of Engineers, 1935) and a stage about 2 ft over

bankfull. This high concentration provides some credibility to

Meriwether Lewis’ evaporative measurement (measurement 2)

2,280

1,920

2,330

0

2,000

4,000

6,000

8,000

10,000

SUSPENDED-SEDIMENT CONCENTRATION, IN PARTS PER MILLION

A

378 456

B

(36)

(36)

(36)

(234)

(298)

Omaha,

Nebraska

Omaha,

Nebraska

Kansas City,

Missouri

Near

St. Charles,

Missouri

Hermann,

Missouri

Monthly samples Individual samples

25th percentile

Minimum

Maximum

Number of samples

50th percentile 

 (Median and value)

75th percentile

2,330

(36)

EXPLANATION

Figure 3. Summary of monthly suspended-sediment concentrations in the Missouri River from (A) July 1, 1929, through 

June 30, 1932 (Chief of Engineers, 1935) and (B) individual samples collected from 1973 through 2002 (U.S. Geological 

Survey at http://nwis.waterdata. usgs.gov/mo/nwis/qwdata, accessed on July 1, 2005).

 The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River
1,500 1,575

1,300

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

TURBIDITY, IN JACKSON TURBIDITY UNITS

25 54

0

200

600

800

400

1,000

1,200

TURBIDITY, IN NEPHELOMETRIC TURBIDITY UNITS

Omaha,

Nebraska

Omaha,

Nebraska

Kansas City, 

Kansas

St. Charles, 

Missouri

Hermann,

Missouri

A (36) B

(38)

(36)

(49)

(298)

Individual depth-integrated samples

1973 through 2001

10-day composite of grab samples

 1907 water year 

25th percentile

Minimum

Maximum

Number of samples

50th percentile 

 (Median and value)

75th percentile

1,300

(36)

EXPLANATION

Figure 4. (A) Turbidity in 10-day composite of grab samples collected in the 1907 water year (Dole, 1909) and 

(B) Turbidity in depth-integrated samples collected from 1973 through 2001 (U.S. Geological Survey at http://nwis.

waterdata.usgs.gov/mo/nwis/qwdata, accessed July 1, 2005). NOTE: Jackson Turbidity Units and Nephelometric 

Turbidity Units are not necessarily equivalent at values greater than 40 because of the use of different methods of 

measurement (American Public Health Association, American Water Works Association, and Water Environment 

Federation, 2005).

of 10,600 mg/L. Conversely, the 1929 to 1932 data cast more

doubt on the settleable-sediment observations of Clark and

Harris. The median of monthly concentrations in the 1929 to

1932 data, collected 9-river miles upstream from St. Charles,

Missouri, was 1,920 ppm (fig. 3), which is more than, but

comparable to, Teichmann’s January to October 1900 median

(1,600 ppm) of daily samples and Dole’s 1907 median (also

1,600 ppm; fig. 2) of 10-day composite samples. The lower

concentrations reported by Teichmann and Dole may partly be

caused by under representation of suspended sediment in grab

samples collected near the water surface.

Turbidity

The large suspended-sediment concentrations in the

uncontrolled river caused it to be so turbid that the water usually was opaque:

 “One of the difficulties, the navigator never ceases 

to contend with, from the entrance of the Missouri 

to this place (near present-day Bismarck, North

Dakota)... [is] the turbed [sic] quality of the water, 

which renders it impracticable to discover any 

obstruction even to the debth [sic] of a single inch.”

(Meriwether Lewis 1804, in Jackson, 1978).

Large concentrations of sediment in the lower Missouri

River before major river modifications in the 1930s also are

reflected in the large values of turbidity reported by Dole

(1909; fig. 4). The longitudinal variability of turbidity was

small in 1907 as the median, 25th, and 75th percentile values for Kansas City, Kansas, and St. Charles, Missouri, are

nearly identical (fig. 4). At Omaha, Nebraska, located above

the Platte River and with lower velocities [William Clark

(in Moulton, 1986)], the median turbidity was only 13 to 18

percent less than at the other two sites. Turbidity was well correlated with suspended-sediment concentrations (r2

=0.91; fig. 5)

at Kansas City, Kansas, and other sites.

Comparison with Modern 

Measurements

Historically, suspended-sediment concentrations were

reported in parts per million, whereas milligrams per liter are

used for modern samples. However, the difference in these

units is less than the precision of the laboratory analyses at

the concentrations reported, except for the three large concentrations observed by William Clark, Meriwether Lewis, and

Edward Harris (measurements 1 to 3), that require corrections

for sample density. Therefore, except for these three values,

comparisons between historical concentrations in parts per

million and modern concentrations in milligrams per liter are

reasonable. Comparing post-1972 with pre-1932 data shows

how severely suspended-sediment concentrations and turbidity

have decreased in the lower Missouri River. The 1973 through

Comparison with Modern Measurements 
2002 median suspended-sediment concentration of 234

instantaneous samples collected at Omaha, Nebraska, is 456

mg/L, which is less than 30 percent of the median suspendedsediment concentration of 10-day composite samples collected

in 1907 by Dole (1909; figs. 2 and 3). The modern median is

also less than 20 percent of the median of monthly suspendedsediment concentrations at the same city, from July 1, 1929,

through June 30, 1932, (fig. 3). The median suspended-sediment concentration at Hermann, Missouri, from 1973 through

2002 is 378 mg/L, which is less than 10 percent of the average

concentration in 1879, less than 25 percent of the median concentration in 1907 (fig. 2), and is less than 20 percent of the

1929 to 1932 median concentration near St. Charles, Missouri.

Comparisons of modern data with the three nonsystematic measurements of the early explorers are even more

remarkable. Clark’s settleable-sediment measurement near

Kansas City, Missouri, is 210 to 270 times the modern median

concentrations at Omaha, Nebraska, and Hermann, Missouri,

and more than 21 times the maximum concentration measured

at these two sites from 1973 through 2002. Although, Meriwether Lewis’ suspended-sediment measurement of 10,600

mg/L is much less than Clark’s and Harris’s observations, it is

still more than 6,000 mg/L greater than the maximum concentration measured at Omaha, Nebraska, since 1973.

Unfortunately, Dole’s measurements of turbidity in 1907

used a different method and different units (Jackson turbidity

units, JTU) than modern measurements (nephelometric turbidity units). Consequently, the measurements are not necessarily equivalent at values greater than about 40 JTU (American

Public Health Association, American Water Works Association, and Water Environment Federation, 2005). Nevertheless,

the difference between the medians of these two data sets is

greater than an order of magnitude (fig. 4), which indicates an

exceptional increase in water clarity.

The effects of reservoirs on turbidity also are evident in

analyses of samples (using a consistent method of analysis)

collected at the Kansas City, Kansas, water-treatment plant

from 1918 to 1954 (U.S. Department of Health, Education,

and Welfare—Public Health Service, 1955; fig. 6). Fort Peck

Dam closed in 1937, Fort Randall Dam in 1952, and Garrison Dam in 1953. Almost immediately turbidity decreased

by more than 50 percent. Given the strong relation between

turbidity and suspended sediment, the reservoirs likely exacted

a similar effect on suspended sediment. Later dams and further

bank stabilization likely decreased turbidity even more. These

data indicate reservoirs and bank stabilization of the 1950s

have decreased turbidity more than the bank stabilization of

the early 1930s (fig. 4).

Figure 5. Turbidity with suspended-sediment concentration at 

Kansas City, Kansas, in the 1907 water year.

0

500

1,000

1,500

2,000

2,500

3,000

3,500

1917

19181919

1920

1921

1922

1923

1924

1925

1926

1927

19281929

19301931

19321933

1934

1935

1936

1937

19381939

1940

1941

1942

1943

1944

1945

1946

1947

1948

1949

1950

1951

1952

1953

1954

1955

TURBIDITY, IN PARTS PER MILLION AS SILICA 

First period 

of intense 

bank stabilization

Second period 

of intense 

bank stabilization Closure of Garrison Dam

Turbidity

Trend

Closure of Fort Peck Dam

Closure of Fort Randall Dam

NOTE: Jackson Turbidity Units are 

 equivalent to parts per million silica

Figure 6. Average annual turbidity at the Kansas City, Kansas, Water Plant, 1918 through 1954 (U.S. Department of Health, Education, 

and Welfare—Public Health Service, 1955) with best-fit fourth-order polynomial trend line.

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

0 1,000 2,000 3,000 4,000 5,000 6,000

TURBIDITY, IN JACKSON TURBIDITY UNITS

SUSPENDED-SEDIMENT

CONCENTRATION,

IN PARTS PER MILLION

r2 = 0.91

Dole (1909)

   The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River
River Velocities

The large historical decrease in suspended sediment and

turbidity seems inconsistent with the common assumption

that the Missouri River flows much faster than it did before

bank stabilization. However, comparison of modern velocity

measurements with available measurements made before bank

stabilization indicate that while mean velocities are similar,

maximum velocities in the lower Missouri River were substantially larger before bank stabilization than maximum velocities measured today. For example, the 25 predevelopment

discharge measurements made at Waverly, Missouri, (fig. 1)

between October 1928 and May 1930 have mean water velocities that are only 0.2 to 0.8 ft/s (foot per second) slower than

mean velocities measured at this same site between October

1993 through September 2002 (fig. 7). However, maximum

water velocities before bank stabilization were actually 1.1 to

1.6 ft/s faster than modern maximum velocities (fig. 8). The

maximum velocity measured at this same site with a logline

by William Clark on June 17, 1804, was 12.5 ft/s (Moulton,

1986), which is close to the maximum high-water velocity of

11.9 ft/s measured in 1929 before bank stabilization. These

data refute the hypothesis that the Missouri River was substantially slower before bank stabilization and help explain how

the river could suspend such large quantities of sediment and

sustain such high turbidity values (fig. 7). Slightly lower mean

velocities and substantially higher maximum velocities before

bank stabilization indicate the range and spatial variation of

water velocity was likely greater before bank stabilization.

Conclusions and Implications

Median suspended-sediment concentrations in the lower

Missouri River appear to have decreased by at least 70 to 80

percent from predevelopment conditions, although two semiquantitative sediment-settling observations made by William

Clark and Edward Harris indicate even larger reductions in

maximum concentrations. Regardless of the amount of reliability that might be ascribed to the Clark and Harris measurements, the decrease in suspended-sediment concentrations and

increase in water clarity of the Missouri River is remarkable. 

Most of this decrease occurred after the closure of dams and

massive bank stabilization activities that occured in the 1950s

and 1960s. The ecological change that may have resulted from

the decrease in suspended-sediment and turbidity has not been

documented. However, numerous ecological changes can be

postulated from fundamental principles of aquatic ecology

(Horne and Goldman, 1994). For example, the greater range

in velocities likely resulted in a greater range in turbidity and

a greater variety of fish habitat. Also, increased water clarity

may permit algal photosynthesis at low river stages providing

a new energy source for the food chain and a niche for nonnative planktivorus fish. Increased water clarity should benefit

sight-feeding fish, perhaps at the expense of native fish such

as catfish, drum, and the endangered pallid sturgeon, that need

little light to find food. Thus, the top end of the food chain

also may be altered with a potential trophic cascade that could

substantially alter the food chain and populations of many

species. Conversely, drinking-water suppliers and other users

Computed concentration of a single observation by Edwin James on May 24, 1843, near present-day Gavins 

Point Dam.

Computed concentration of a single sample collected by William Clark on June 21, 1804, near present-day 

Kansas City, Missouri.

Computed concentration of a single sample collected by Meriwether Lewis in 1804 between Bismarck, 

North Dakota, and the mouth of the Missouri River.

Mean concentration of daily samples collected by U.S. Army Corps of Engineers at St. Charles, Missouri, 

from February 1 to October 31, 1879.

Median concentrations of monthly means of daily samples collected by the U.S. Army Corps of Engineers at 

Omaha, Nebraska; Kansas City, Missouri; and St. Charles, Missouri, from July 1, 1929, through June 30, 1932.

Median concentrations of 10-day composite grab samples collected by Richard Dole of the U.S. Geological 

Survey at Omaha, Nebraska; Kansas City, Kansas; and St. Charles, Missouri, from October 4, 1906, to 

October 14, 1907.

Median concentration of daily grab samples collected by William Teichmann near St. Charles, Missouri, 

from January 24 through October 10, 1900.

Median concentration of individual samples collected by the U.S. Geological Survey from October 1, 1972, 

through September 30, 2002, at Omaha, Nebraska, and Hermann, Missouri.

160,000

98,000

10,600

4,100

1,920 – 2,330

1,550 – 1,710

1,600

456 – 378

Milligrams

per liter or

parts per

million

Comparison of Suspended-Sediment Concentrations from Sources Cited in this Report

Conclusions and Implications 
who must remove river sediments benefit from the decrease in

suspended material.

References

American Public Health Association, American Water Works

Association, and Water Environment Federation, 2005,

Standard methods for the examination of water and wastewater, (21st ed.), 900 p.

Chief of Engineers, 1935, Letter from Secretary of War, 73rd

Congress, 2nd session, House Document No. 238: United

States Government Printing Office, Washington, D.C.,

1,245 p.

Chittenden, H., 1903, History of early steamboat navigation on

the Missouri River: New York, Francis P. Harper, v. 2, 420

p.

Dole, R.B., 1909, The quality of surface waters of the United

States: U.S. Geological Survey Water-Supply Paper 236,

123 p.

Hauck, H.S., and Nagel, C.D., 2002, Water resources data—

Missouri, water year 2002: U.S. Geological Survey Water

Data Report MO–02–1, 543 p.

Horne, A.J., and Goldman, C.R., 1994, Limnology, (2nd ed):

McGraw-Hill, 576 p.

Husted, Mrs. W., ed., 1957, Virginia Cookery Past and Present: The Woman’s Auxiliary of Olivet Episcopal Church

Franconia, Virginia, p. 431.

Innis, B., 1985, Sagas of the Smoky-Water: Williston, North

Dakota, Centennial Press, 432 p.

Jackson, D., 1978, Letters of the Lewis and Clark Expedition

with Related Documents, 1783–1854 (2nd ed.): Urbana,

University of Illinois Press, p. 222–25.

Keown, M.P., Dardeau, E.A., and Causey, E.M., 1981, Characterization of the suspended-sediment regime and bed-material gradation of the Mississippi River Basin: U.S. Army

Corps of Engineers Waterways Experiment Station Potamology Program Report 1, v. 1, 494 p.

Leighton, M.O., 1907, Pollution of Illinois and Mississippi

Rivers by Chicago Sewage: U.S. Geological Survey WaterSupply and Irrigation Paper No. 194, Series L, Quality of

Water 20, 369 p.

McDermott, J.F., 1951, Up the Wide Missouri with Audubon:

the Journal of Edward Harris: University of Oklahoma

Press, 222 p.

Moulton, G., ed., 1986, The Journals of the Lewis & Clark

Expedition (v. 2): University of Nebraska Press, Lincoln,

Nebraska, 612 p.

Stevens, G.C., and Hardison, C.H., 1951, Monthly and annual

discharge of Missouri River between Fort Benton, Montana

And Hermann, Missouri, and principle tributaries: U.S:

Geological Survey Circular 108, 37 p.

U.S. Department of Health, Education, and Welfare—Public

Health Service, 1955, Central Missouri River Water Quality

Investigation, 79 p.

r2 = 0.85

r2 = 0.89

0 50,000 100,000 150,000 200,000 250,000

DISCHARGE, IN CUBIC FEET PER SECOND

MEAN WATER VELOCITY, IN FEET PER SECOND

October 1928 through May 1930

October 1993 through September 2002

0

2

4

6

8

10

12

14

Figure 7. Relation between mean water velocity and discharge 

in the Missouri River at Waverly, Missouri, as recorded in U.S. 

Geological Survey discharge measurement notes.

0 50,000 100,000 150,000 200,000 250,000

DISCHARGE, IN CUBIC FEET PER SECOND

October 1928 through May 1930

October 1993 through September 2002

MAXIMUM

WATER VELOCITY, IN FEET PER SECOND

r2 = 0.83

r2 = 0.80

0

2

4

6

8

10

12

14

Figure 8. Relation between maximum water velocity and 

discharge in the Missouri River at Waverly, Missouri, as recorded 

in U.S. Geological Survey discharge measurement notes.

   The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River
Closure of Big Bend Dam in 1963. Construction of six large reservoirs on the upper Missouri 

River have greatly decreased the amount of suspended sediment and turbidity in the lower 

river. (Photograph courtesy of the U.S. Army Corps of Engineers.)
Blevins—The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River—Circular 1301

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