U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008–5123

Prepared in cooperation with the 

U.S. Army Corps of Engineers

Characterization of Suspended Sediment Loading 

to and from John Redmond Reservoir, East-Central 

Kansas, 2007–2008
U.S. Department of the Interior

U.S. Geological Survey

Cover. Outflow from John Redmond Reservoir, east-central Kansas (photograph taken by Ashli Maddox, U.S. Geological Survey).
Characterization of Suspended-Sediment 

Loading to and from John Redmond 

Reservoir, East-Central Kansas, 2007–2008

By Casey J. Lee, Patrick P. Rasmussen, and Andrew C. Ziegler

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

Scientific Investigations Report 2008–5123

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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Suggested citation:

Lee, Casey J., Rasmussen, Patrick P., and Ziegler, Andrew C., 2008, Characterization of suspended-sediment loading to 

and from John Redmond Reservoir, east-central Kansas, 2007–2008: U.S. Geological Survey Scientific Investigations 

Report 2008–5123, 25 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Description of Study Area ...................................................................................................................3

Previous Sediment Transport Investigations ...................................................................................3

Methods...........................................................................................................................................................4

Continuous Water-Quality and Streamflow Monitoring.................................................................4

Suspended-Sediment Sample Collection and Analysis .................................................................5

Quality Assurance.................................................................................................................................5

Regression Models...............................................................................................................................5

Computation of Sediment Concentrations, Loads, and Yields.......................................................6

Characterization of Sediment Loading To and From John Redmond Reservoir..................................7

Hydrologic Conditions..........................................................................................................................7

Regression Models...............................................................................................................................9

Stormflow Effects on Sediment Loading.........................................................................................10

Effects of Upstream Reservoirs on Sediment Loading.................................................................15

Trapping Efficiency and Storage Loss.............................................................................................16

Comparison to Historical Data..........................................................................................................19

Summary and Conclusions.........................................................................................................................20

References Cited..........................................................................................................................................23

Figures

1. Map showing location of watershed boundaries, land use, and sampling sites 

upstream and downstream from John Redmond Reservoir, east-central Kansas, 

February 2007–2008 ......................................................................................................................2

2–11. Graphs showing:

2. Relation between cross-sectional median and in-stream turbidity readings at John 

Redmond sites, February 2007–2008..........................................................................................6

3. Annual flow at John Redmond sites, 1964–2007......................................................................8

4. Time-series streamflow values and storms delineated by number, John Redmond sites, 

February 2007–2008 ......................................................................................................................9

5. Streamflow duration curves at John Redmond sites, February 2007–2008 ......................10

6. Regression models between optical sensors and suspended-sediment concentration 

at study area sites, February 2007–2008 .................................................................................13

7. Relation between sediment loading and streamflow volume during stormflow events at 

John Redmond sites, February 2007–2008..............................................................................16

8. Suspended-sediment load duration curves at John Redmond sites, February 

2007–2008 .....................................................................................................................................17

9. Estimation of streamflow and sediment loading originating from Council Grove 

Reservoir at the Neosho River near Americus, April 8–26, 2007 ........................................19

10. Approximate suspended-sediment load to and from John Redmond Reservoir, 

February 2007–2008 ....................................................................................................................20
iv

11. Relations between streamflow and suspended-sediment load (SSL) for historic 

sediment samples at study area sites.....................................................................................22

Tables

1. Location and contributing drainage area of sampling sites upstream and downstream 

from John Redmond Reservoir, east-central Kansas, February 2007–08............................3

2. Approximate land use in riparian areas of various sized streams in the Neosho River 

basin, east-central Kansas, 2004 ...............................................................................................4

3. Suspended-sediment concentration, percent silt/clay (<63 um diameter), and grainsize distribution from discrete samples collected from John Redmond sites, February 2007–2008 ..............................................................................................................................11

4. Regression models and statistics for estimating suspended-sediment concentration 

(SSC) from turbidity values at study area sites, February 2007–2008 ................................12

5. Dates, streamflow, and suspended sediment loading of stormflow for study period at 

John Redmond sites, February 2007–2008..............................................................................14

6. Streamflow, sediment load, and sediment yield from regulated and unregulated drainage areas at monitoring sites upstream from John Redmond Reservoir, 

February 2007–08 ........................................................................................................................18

7. Estimate of storage lost in John Redmond Reservoir under varying estimates of bulk 

density, February 2007–08 .........................................................................................................20

8. Regression models and statistics for estimating suspended-sediment load (SSL) using 

historic (1964–1978) sediment and streamflow at study area sites, February 

2007–2008 .....................................................................................................................................21

9. Comparison of total sediment loads estimated from turbidity (2007–2008) and historic 

(1964–1978) streamflow measurements , February 2007–2008 ...........................................23
v

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m) 

foot per mile 0.1894 meter per kilometer

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3) 

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

cubic foot per day (ft3/d) 0.02832 cubic meter per day (m3/d)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

acre-foot 1,233 cubic meter (m3)

acre-feet per square mile 476 cubic meters per square kilometer

Weight

ton 2,000 pound

ton per square mile 0.3503 metric ton per square kilometer

ton per square mile per year 0.003503 metric ton per hectare per year

pound per cubic foot 16.02 kilogram per cubic meter

Rate

tons per day 0.0231 pounds per second

pounds per second 0.453592 kilograms per second

pounds per day 0.4536 kilograms per day

tons per year 0.9072 metric tons per year

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

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

(NAVD 88).

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

Abstract

Storage capacity in John Redmond Reservoir is being lost 

to sedimentation more rapidly than in other federal impoundments in Kansas. The U.S. Geological Survey, in cooperation 

with the U.S. Army Corps of Engineers, initiated a study to 

characterize suspended-sediment loading to and from John 

Redmond Reservoir from February 21, 2007, through February 21, 2008. Turbidity sensors were installed at two U.S. 

Geological Survey stream gages upstream (Neosho River near 

Americus and the Cottonwood River near Plymouth) and one 

stream gage downstream (Neosho River at Burlington) from 

the reservoir to compute continuous, real-time (15-minute) 

measurements of suspended-sediment concentration and loading. 

About 1,120,000 tons of suspended-sediment were 

transported to, and 100,700 tons were transported from John 

Redmond Reservoir during the study period. Dependent on the 

bulk density of sediment stored in the reservoir, 5.0 to 1.4 percent of the storage in the John Redmond conservation pool 

was lost during the study period, with an average deposition of 

3.4 to 1.0 inches. Nearly all (98–99 percent) of the incoming 

sediment load was transported during 9 storms which occurred 

25 to 27 percent of the time. The largest storm during the 

study period (peak-flow recurrence interval of about 4.6–

4.9 years) transported about 37 percent of the sediment load to 

the reservoir. Suspended-sediment yield from the unregulated 

drainage area upstream from the Neosho River near Americus 

was 530 tons per square mile, compared to 400 tons per square 

mile upstream from the Cottonwood River near Plymouth.

Comparison of historical (1964–78) to current (2007) 

sediment loading estimates indicate statistically insignificant 

(<90 percent confidence) differences at the Neosho River 

near Americus and the Cottonwood River near Plymouth, but 

a significant (>99 percent) decrease in sediment loading at 

the Neosho River at Burlington. Ninety-percent confidence 

intervals of streamflow-derived estimates of total sediment 

load were 7 to 21 times larger than turbidity-derived estimates. Results from this study can be used by natural resource 

managers to calibrate sediment models and estimate the ability 

Characterization of Suspended-Sediment Loading to 

and from John Redmond Reservoir, East-Central Kansas, 

2007–2008

By Casey J. Lee, Patrick P. Rasmussen and Andrew C. Ziegler

of John Redmond Reservoir to support designated uses into 

the future. 

Introduction

John Redmond Reservoir was constructed from 1959 

through 1964 for purposes of flood control, water supply, and 

recreation (U.S. Corps of Engineers, 2002). The reservoir is 

on the Neosho River and drains 3,015 square miles of mostly 

grassland and cropland (fig. 1). Seventy-one percent of water 

rights downstream from John Redmond are allocated for 

purposes of cooling the Wolf Creek Nuclear Power Plant (U.S. 

Army Corps of Engineers, 2002). Fourteen percent of the 

water rights are allocated to municipalities, 10 percent to irrigation and recreational uses, and 5 percent for industrial uses. 

Sediment deposition threatens the ability of John Redmond 

Reservoir to support designated uses. Approximate sedimentation rates to John Redmond Reservoir from 1964–2006 

(874 acre-feet per year) are more than double the designed 

sedimentation rate (404 acre-ft/year; Kansas Water Office, 

2008b). Since the closing of the dam in 1964, John Redmond 

has lost 46 percent of storage in the multipurpose pool; the 

largest percentage of federally owned reservoirs in the State 

of Kansas (Kansas Water Office, 2008b). The Kansas Department of Health and Environment has identified impairments 

to ecosystem quality in the Neosho and Cottonwood River 

upstream from John Redmond Reservoir because of excessive 

siltation and nutrient loading (Kansas Department of Health 

and Environment, 2003). 

The Kansas Water Office and the U.S. Army Corps of 

Engineers initiated a watershed feasibility study to identify 

strategies to ensure the long-range availability of habitat, 

water storage capacity, and ecosystem function within John 

Redmond Reservoir and the surrounding watershed. The 

U.S. Geological Survey (USGS), in cooperation with the 

U.S. Army Corps of Engineers, characterized suspendedsediment loading to and from John Redmond Reservoir for 

part of this overall study. Results from this study can be used 

by resource managers to assess the ability of the reservoir to 

support designated uses now and in the future. 
2 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

97°30' 97°00’ 96°30' 96°00’ 39°00’

38°30'

38°00’

0 10 20 MILES

0 10 20 KILOMETERS

Land use from U.S. Geological Survey National

 Landcover Database, (Horner and others, 2004)

Cottonwood

River

River

Neosho

Council Grove

Lake

Marion 

Reservoir

Cottonwood

River near

Plymouth

North 

Cottonwood

River near

Marion Reservoir

Neosho River

at Burlington

John

Redmond 

Reservoir

75

335

Base map from U.S. Geological Survey digital data, 1:2,000,000, 1994

Albers Conic Equal-Area Projection,

Standard parallels 29°30' and 45°30', central meridian 96°

Horizontal coordinate information is referenced to the

North American Datum of 1983 (NAD 83)

56

56

35

35

50

50

50

COFFEY

BUTLER GREENWOOD WOODSON

HARVEY

Neosho River

near Americus

Neosho River

at Council Grove

77

77

Emporia

Council Grove

Boundary of drainage basin upstream 

 from stream-gaging station at Burlington

Boundary of subbasin

U.S. Geological Survey stream-gaging 

 station and turbidity monitoring

 station

U.S. Geological Survey stream-gaging 

 station

EXPLANATION

Land use (within basin)

Open water

Urban development/roads

Forest

Grassland/shrubland

Pasture/hay

Cultivated cropland

Wetlands

MARION

CHASE 

Index map

MARION

CHASE 

MCPHERSON

MORRIS

GEARY

SALINE

DICKINSON

LYON

WABAUNSEE

OSAGE

KANSAS

Location of 

study area

SHAWNEE

Figure 1. Location of watershed boundaries, land use, and sampling sites upstream and downstream from John Redmond 

Reservoir, east-central Kansas, February 2007–2008.
Introduction 3

Purpose and Scope

The purpose of this report is to estimate suspendedsediment loading to and from John Redmond Reservoir from 

February 21, 2007, to February 21, 2008. Sediment loads 

are computed at three sites near inflow/outflow locations of 

the reservoir through collection of continuous turbidity and 

streamflow data. Data from this report can be used to estimate 

the useful lifetime of the reservoir and calibrate models to 

predict future sediment loading. The approach developed in 

this study can be used at additional impoundments in the State 

of Kansas to estimate sediment loading, trapping efficiency, 

and the length of time reservoirs will continue to support 

designated uses.

Description of Study Area 

The study area is in the Osage Plains section of the Central Lowland Province (Schoewe, 1949). Study area streams 

typically have deep, narrow valleys with outcropping rock 

ledges (Carswell and Hart, 1985). The Neosho River (excluding the Cottonwood River tributary) drains about 1,110 square 

miles (mi2) upstream from John Redmond Reservoir and has 

a slope ranging from 3 feet per mile (ft/mile) near Council 

Grove to 1.5 ft/mile near Emporia (Carswell and Hart, 1985). 

The largest tributary to the Neosho River is the Cottonwood 

River, which runs a length of about 127 river miles and drains 

about 1,900 square miles. River slope ranges from 3.5 ft/mile 

in the headwaters to 1.5 ft/mile near Emporia (Jordan and 

Hart, 1985). Silty-clay loam (material with 27 to 40 percent 

clay and less than 20 percent sand) is the dominant soil type 

along riparian areas and farther downstream in the watershed. 

Silty clay (material with 40 percent or more clay and 40 percent or more silt) is the dominant soil type in the upstream part 

of the basin (U.S. Department of Agriculture, 1994). Erodibility of these soil classes generally are similar (Brady and 

Weil, 1999).

USGS stream gages on the Neosho River near Americus 

and the Cottonwood River near Plymouth are the farthest 

downstream gages prior to stream entry to John Redmond Reservoir (table 1). These gages are downstream from 2,362 mi2 

of the approximate 3,015 mi2 that drains to the reservoir 

(U.S. Army Corps of Engineers, 2002). Two federally-owned 

impoundments regulate streamflow in the watershed draining 

to John Redmond. Council Grove Lake has a drainage area of 

246 mi2 on the upper Neosho River, and Marion Reservoir has 

a drainage area of 200 mi2 on the upper Cottonwood River. 

Council Grove Lake impounds 40 percent of the watershed 

upstream from the stream gage at Americus; Marion Reservoir impounds 11 percent of the watershed upstream from the 

stream gage at Plymouth. 

Land use in the John Redmond basin is mostly grassland, 

with substantial areas of cultivated crops and land devoted 

to pasture/hay (fig. 1). Cultivation of surface soils have been 

observed to increase sediment yield compared to undisturbed 

and (or) grassland conditions (Wolman, 1967). Unprotected 

cropland has been cited as the primary source of sediment to 

Kansas streams (Devlin and McVay, 2001). Areas of cultivation are concentrated in the headwater parts of the watershed 

(primarily of the Cottonwood River) and along the riparian 

corridor of larger streams (fig. 1). Riparian vegetation has 

been shown to decrease sediment flux to streams (Lee and others 2003; McKergow and others, 2003) whereas disturbance 

in riparian areas result in easily transportable sediment. To 

estimate the extent and location of cropland in riparian areas, 

land-use was defined for buffers of 160 and 1,000 feet along 

streams with approximate mean annual flows of 0.1, 1, and 

10 cubic feet per second (table 2). The riparian areas of larger 

streams had the most cropland because of fertile, alluvial soils. 

Grassland was the dominant land use in the riparian areas of 

smaller streams. 

Previous Sediment Transport Investigations 

Few studies have been performed on sediment transport 

in the upper Neosho or Cottonwood Rivers. Collins (1965) 

characterized average sediment yields as ranging from 750 to 

2,000 tons per square mile per year (tons/mi2/yr) in the study 

Table 1. Location and contributing drainage area of sampling sites upstream and downstream from John Redmond Reservoir eastcentral Kansas, February 2007–May 2008.

[mi2, square mile]

U.S. Geological Survey 

identification 

number

Site name

(fig. 1)

Total 

drainage 

area (mi2)

Unregulated 

drainage 

area (mi2)

Nearest upstream reservoir and 

corresponding regulated 

drainage area (mi2)

Latitude, 

in degrees, 

minutes, and 

seconds

Longitude, 

in degrees, 

minutes, and 

seconds

07179730 Neosho River near 

Americus

622 376 Council Grove Lake (246) 38°28'01" 96°15'01"

07182250 Cottonwood River near 

Plymouth

1,740 1,540 Marion Lake (200) 38°23'51" 96°21'21"

07182510 Neosho River at 

Burlington

3,042 27 John Redmond Reservoir (3,015) 38°11'40" 95°44'40"
4 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

area, and characterized erosion hazards as primarily relating to sheet and gully erosion on sloping croplands and on 

overgrazed pastures. Yu and others (1993) analyzed trends 

in water-quality data collected in the Neosho River upstream 

and downstream from John Redmond Reservoir from 1973–

1988. The study found no detectable trend in streamflow or 

suspended-solids concentration upstream from John Redmond 

Reservoir and a statistically significant downward trend in 

suspended-solids concentration downstream from the reservoir. The Kansas Department of Health and Environment 

(KDHE) collected water-quality data in study area streams and 

reservoirs to establish total maximum daily loads (TMDLs) 

to determine impairments. KDHE has established TMDLs for 

siltation of John Redmond Reservoir and Council Grove Lake, 

and eutrophication TMDLs for John Redmond Reservoir, 

Council Grove Lake, and Marion Reservoir (Kansas Department of Health and Environment, 2002, 2003a, 2003b, 2005). 

Many studies have been performed that provide precedent for approaches used in this study. Christensen and others, 

(2000), Putnam and Pope (2003), and Rasmussen and others 

(2005) have shown that continuous turbidity and streamflow 

provide accurate computations of suspended-sediment concentrations, loads, and yields in selected Kansas streams. 

Methods

Continuous Water-Quality and Streamflow 

Monitoring

USGS streamflow-gaging stations on the Neosho River 

near Americus (hereafter Americus), the Cottonwood River 

near Plymouth (Plymouth), and the Neosho River at Burlington (Burlington) (table 1, fig. 1) were equipped with YSI 6600 

continuous water-quality monitors that measured specific conductance, water temperature, and turbidity (model 6136). Sensors collected values in stream, and were housed in polyvinyl 

chloride pipes drilled with holes to allow stream water to flow 

through the installation. Sensors at Americus and Plymouth 

were installed along the bank nearest the stream gage, and sensors at Burlington were suspended from a bridge by chain near 

the center of the stream. Measurements were logged every 

15 minutes, and data are available in real time on the USGS 

Web pages http://ks.water.usgs.gov/Kansas/rtqw/. Historic and 

current analyses of water-quality samples at monitoring sites 

are available on the USGS web page http://waterdata.usgs.

gov/ks/nwis/qw.

Table 2. Approximate land use in riparian areas of various sized streams in the Neosho River basin, east-central Kansas, 2004.

[Data from the U.S. Geological Survey National Landcover Database, Homer and others, 2004; mi2, square mile; ft3/s, cubic feet per second]

Stream size designation Area 

(mi2)

Percentage land use

Open 

water

Urban 

development/

roads

Forest Grassland

Pasture/

hay

Cultivated 

crops

Wetlands/

streams

160-foot buffer riparian area

Stream with mean annual flow less 

than or equal to 0.1 ft3/s

247 1.7 3.0 19.1 47.7 8.3 12.8 7.4

Stream with mean annual flow less 

than or equal to 1 ft3/s

99 1.9 3.0 32.2 23.9 8.8 15.0 15.2

Stream with mean annual flow less 

than or equal to 10 ft3/s

31.4 4.5 2.6 33.7 6.2 6.4 17.7 29.0

1,000-foot buffer riparian area

Stream with mean annual flow less 

than or equal to 0.1 ft3/s

706 .9 3.6 10.3 53.6 8.8 19.1 3.7

Stream with mean annual flow less 

than or equal to 1 ft3/s

277 1.1 3.8 18.8 33.2 10.5 24.3 8.3

Stream with mean annual flow less 

than or equal to 10 ft3/s

87.2 2.3 3.6 22.0 12.4 9.9 33.4 16.4
Methods 5

 Monitor maintenance and data reporting commonly followed procedures described in Wagner and others (2006), with 

the exception of increased length between calibration checks 

(~2 months). Fewer calibration visits were necessary because 

dissolved oxygen and pH data were not collected at monitoring sites. Sensors were cleaned and calibrated approximately 

bimonthly; additional cleaning visits were made when realtime data indicated error because of environmental fouling. 

Quality-assurance checks were made before and after sensor 

cleaning and calibration with an independently calibrated 

sensor. Fouling or calibration errors found during these visits 

were used to compute data corrections and estimate error in 

the continuous-data record.

Because in-stream turbidity conditions occasionally 

exceeded the upper measurement limit of nephelometric YSI 

6136 turbidity sensors, optical-backscatter Hach SOLITAX SC 

turbidity sensors (SOLITAX) were installed at Americus and 

Plymouth adjacent to YSI sensors. The SOLITAX sensor uses 

an internal algorithm to convert backscatter signal strength to 

an estimate of suspended-solids concentration. SOLITAX sensors have an approximate range from 0 to 50,000 milligrams 

per liter (mg/L) of suspended solids (Hach Company, 2005) 

and were installed to estimate suspended-sediment concentration (SSC) when YSI turbidity values were missing or more 

than the published range (1,000 formazin nephelometric units 

(FNUs); YSI, 2007). YSI 6136 turbidity and SOLITAX suspended-solids data have shown linearity throughout observed 

values (Lee and others, 2006). Because there are no independent calibration methods recommended for the SOLITAX 

by the manufacturer, and because experimental calibration 

methods did not yield consistent results, independent regression models were developed to estimate error in SOLITAX 

estimates of suspended-sediment concentration. 

Time-series turbidity measurements were occasionally 

missing or deleted from the continuous record because of 

equipment malfunctions and (or) environmental fouling. Values for these periods were estimated to allow for an unbiased 

comparison of suspended-sediment loading among sampling 

sites. Values were interpolated among measured data points 

for missing record during stable streamflow (Rasmussen and 

Ziegler, 2003; Rasmussen and others, 2005). SSC values were 

computed using data from SOLITAX sensors (rather than the 

YSI) as the explanatory variable for missing YSI turbidity 

values during changing streamflow. SOLITAX sensor values 

were used to compute SSC when YSI turbidity values were 

greater than 1,000 FNU. SOLITAX sensors were removed 

during freezing conditions, and not reinstalled during a storm 

event beginning February 18, 2008, in which turbidity sensors reached maximum values at Americus (for 9 hours) and 

Plymouth (for 5 hours). Although sediment loading is underestimated during this portion of the continuous record, the 

relatively short duration of the maximization is not expected to 

substantially bias total sediment-load computations.

Computing a streamflow time series involved collection of continuous stage records along with periodic streamflow measurements. Observations also were made of factors 

affecting the stage-streamflow relation. Stage records were 

obtained from a water-stage recorder. Streamflow measurements were made with a current meter or acoustic Doppler 

current profiler, using the general methods adopted by the 

USGS. These methods are described in Rantz and others 

(1982) and Oberg and others (2005). A more in-depth description of streamflow time-series computation is beyond the 

scope of this report. These data are available in real time on 

USGS Web pages (http://waterdata.usgs.gov/ks/nwis and 

http://ks.water.usgs.gov/Kansas/rtqw/).

Suspended-Sediment Sample Collection and 

Analysis

Suspended-sediment samples were collected using equalwidth increment methods according to methods described in 

Gray and others (2008) and Nolan and others (2005). Samples 

were analyzed for SSC; selected samples were analyzed for 

grain-size distribution (percent of sediment less than 2, 4, 8, 

16, 31, and 62 micrometers in diameter). Samples were analyzed at the USGS Sediment Laboratory in Iowa City, Iowa, 

using methods described by Guy (1969). 

Quality Assurance

Turbidity values were measured across the width of the 

stream during the collection of suspended-sediment samples. 

Median values of cross-sectional measurements are compared 

with in-stream sensors to assess the ability of the in-stream 

sensor to determine turbidity across the width of the stream. 

Comparisons were accurate (R2 = between 0.91–1.0) and near 

1:1 relation in slope (0.93 to 1.01; fig. 2). Measurements that 

plotted outside of a 1:1 fit likely were caused by localized 

differences in turbidity and (or) instrument error. Because consistent bias was not observed in the relation at any monitoring 

location, values from continuous-water-quality monitors are 

representative of stream-water quality across the width of the 

stream cross section. Turbidity records were generally rated 

good (error of 5–10 percent) and occasionally fair (10–15 percent) based on guidelines developed by Wagner (2006).

Regression Models

Ordinary-least-square regression analysis was used to 

develop statistical relations among SSC, in-stream turbidity, 

and SOLITAX values. Because of data spiking and occasional 

uneven distribution of turbidity near channel banks (fig. 2), 

cross-sectional turbidity measurements were used in place of 

in-stream turbidity measurements for 6 of the 13 samples at 

Plymouth. All values were log-transformed in order to better 

approximate normality and to even the variability in regression 

residuals. After development of the regression model, SSC 

values were retransformed back to linear space. Because this 

retransformation can cause bias when adding instantaneous 
6 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

values of load estimates over time, a log-transformation bias 

correction factor (Duan’s smearing estimator; Duan, 1983) 

was multiplied to correct for potential bias (Cohn and Gilroy, 

1991; Helsel and Hirsch, 1992). Uncertainty of regression 

estimates were determined by 90-percent prediction intervals (Helsel and Hirsch, 1992). Regression methods used in 

this study are described in greater detail in Cohn and others 

(1989), Helsel and Hirsch (1992), and Rasmussen and Ziegler 

(2003). The continuous concentration estimates, uncertainty, 

and duration curves for the three monitoring sites are available on the World Wide Web at URL http://ks.water.usgs.gov/

Kansas/rtqw.

Computation of Sediment Concentrations, Loads, 

and Yields

Instantaneous-suspended-sediment loads were computed 

from time-series turbidity, SOLITAX reported suspendedsolids, and streamflow data as follows: (1) Instantaneous loads 

were computed by first using regression formulas to compute 

suspended-sediment concentration from turbidity data every 

15 minutes. YSI Turbidity regressions were used when values 

were less than 1,000 FNUs (the specified sensor limitation 

of YSI instruments) and if SOLITAX sensors malfunctioned 

while turbidity values were larger than 1,000 FNUs. (2) 

Regressions between SOLITAX and SSC values were used 

whenever YSI turbidity values exceeded 1,000 FNUs, or 

when YSI turbidity data were not recorded because of sensor 

malfunction. 

SSC values computed from regression estimates were 

multiplied by the log-transformation bias correction, and then 

by corresponding streamflow values and a unit conversion to 

compute 15-minute estimates of suspended sediment load in 

pounds per second. These instantaneous computations of sediment load are summed and multiplied by a unit conversion to 

compute sediment loading in tons. The sediment load contributed from a given drainage is divided by upstream drainage 

area to estimate sediment yield. Sediment yields are calculated 

to compare sediment loading among drainages of different 

size, and are not meant to imply equal sourcing of sediment 

throughout the drainage. 

Loads and yields of suspended sediment were estimated 

for the ungaged drainage area upstream from John Redmond 

and downstream from the Americus and Plymouth gages 

(table 1) using data from existing monitoring sites. Because 

Council Grove Lake and Marion Reservoir trap sediment 

upstream from monitoring sites, estimates of sediment loading 

and yield from unregulated parts of monitored drainages are 

required to accurately estimate sediment contributed from 

ungaged parts of the study area. Two assumptions were necessary to distinguish sediment loading between regulated and 

unregulated drainages. First, mean sediment yield upstream 

from Council Grove Lake and John Redmond and Marion 

Reservoirs (prior to trapping by impoundments) were estimated based on results of bathymetric surveys (Kansas Water 

Office, 2008a, 2008b, 2008c). Mean sediment yield upstream 

from Council Grove Lake and Marion Reservoir is estimated 

to be 2.52 times and 1.80 times respectively, that of John 

Redmond (Kansas Water Office, 2008a, 2008b, 2008c). The 

relative differences in sediment yield among reservoirs can 

be used to reflect differences in sediment loading during the 

study period. Second, sediment trapping efficiency at Council Grove Lake and Marion Reservoir is approximated using 

theoretical relations with hydraulic residence time developed 

by Brune (1953). Sediment trapping efficiency was estimated 

as 95 percent in Council Grove Lake and 97 percent in Marion 

Reservoir during the period of study. 

The following equations can be used to estimate sediment loading from regulated and unregulated drainage areas, 

and from ungaged parts of the study area upstream from John 

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120 140 160 180

IN-STREAM TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS (FNUS)

(C) Neosho River at Burlington (fig. 1, station no. 07182510)

0

200

400

600

800

1,000

1,200

1,400

0 200 400 600 800 1,000 1,200

(B) Cottonwood River near Plymouth (fig. 1, station no. 07182250)

y = 1.01x

R2 = 0.94

y = 0.99x

R2 = 0.91

y = 0.93x

R2 = 1.00

0

200

400

600

800

1,000

1,200

0 100 200 300 400 500 600 700 800 900 1,000

MEDIAN CROSS-SECTIONAL TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS (FNUS)

(A) Neosho River near Americus (fig. 1, station no. 07179730)

Figure 2. Relation between cross-sectional median 

and in-stream turbidity readings at John Redmond sites, 

February 2007–08.
Characterization of Sediment Loading to and from John Redmond Reservoir 7

Redmond Reservoir. Sediment loading computed at streamgage sites is presumed to equal the sum of sediment from the 

unregulated drainage, and the regulated drainage area multiplied by one minus the trapping efficiency of the reservoir.

Lg = Li + (1- (Te/100)) Lr (1)

where Lg is sediment load at the stream gage (in tons), Li is 

sediment load of the unregulated drainage area, Te is the trapping efficiency of the upstream reservoir (in percent), and Lr is 

sediment loading to the upstream reservoir. Because sediment 

yield is equivalent to the sediment load divided by upstream 

drainage area, mean sediment yield to Council Grove Lake 

and Marion Reservoir (Kansas Water Office, 2008a, 2008b, 

2008c) were related to the sediment yield of John Redmond to 

estimate loading to upstream reservoirs:

LC/DC = 2.52LJR/DJR (2)

LM/DM = 1.80LJR/DJR (3)

where D is the drainage area upstream from a specified reservoir (in square miles), and L is the sediment load upstream 

from a specified reservoir (in tons). Subscript “C” indicates 

Council Grove Lake, “M” indicates Marion Reservoir, and 

“JR” indicates John Redmond Reservoir. Given drainage areas 

from table 1: 

LC = .206LJR (4)

LM= .119LJR (5)

Thus sediment loading from the unregulated drainage area 

upstream from the Americus gage is calculated as (from 

equation 1):

Lia = Lga – (1 - .95) .206LJR (6)

Sediment loading from the unregulated drainage upstream 

from the Plymouth gage is calculated as (from equation 1):

Lip = Lgp – (1 - .97) .119LJR (7)

where subscript “a” indicates Americus and “p” indicates 

Plymouth. Sediment loading to John Redmond is estimated 

by multiplying sediment yield (load divided by drainage area) 

from the unregulated drainages by the ungaged drainage area:

LJR = Lga + Lgp+ (DdaLia/Dia) + (DdpLip/Dip) + (Ddc(Lia+Lip)/

(Dia + Dip) (8)

where Dda is the ungaged part of the Neosho River downstream 

from the Americus gage (184 mi2), Ddp is the ungaged part 

of the Cottonwood River downstream from the Plymouth 

gage (162 mi2), Ddc is the ungaged part of the Neosho River 

downstream from the confluence with the Cottonwood River 

(307 mi2). After drainage areas are inserted:

LJR = Lga + Lgp+ .489Lia + .105Lip + 

.161(Lia+ Lip) (9)

Given equations 6 and 7 calculating sediment loading from the 

unregulated drainages upstream from Americus and Plymouth:

LJR= Lga + Lgp+ .489(Lga - .0103 LJR) +

.105(Lgp - .0036 LJR) + .161((Lga - .0103LJR) +

(Lgp - .0036 LJR)) (10)

Multiplying it out:

LJR = 1.64 Lga + 1.26 Lgp (11)

Using equation 6 for sediment loading from the unregulated 

drainage area upstream from the Americus gage:

Lia = Lga – (1 - .95).206(1.64 Lga + 1.26 Lgp) (12)

Lia = .983Lga - .013Lgp (13)

Using equation 7 for sediment loading from the unregulated 

drainage area upstream from the Americus gage:

Lip = Lgp – (1 - .97).119(1.64 Lga + 1.26 Lgp) (14)

Lip = .996Lgp - .00059Lga (15)

Although estimating sediment loading to, and trapping efficiency of Council Grove Lake and Marion Reservoir contain 

undefined error, the estimated sediment load and trapping efficiency are likely more accurate than either assuming constant 

sediment yield for the entire drainage upstream from gage 

sites, identical sediment trapping efficiency among reservoirs 

of different size, or neglecting to account for sediment trapping from upstream reservoirs.

Characterization of Sediment Loading 

to and from John Redmond Reservoir

Hydrologic Conditions

Total streamflow observed at gage sites in 2007 was 

similar to median historical streamflow (fig. 3). Median 

annual streamflow (calculated by summing mean daily values) from the Americus, Plymouth, and Burlington gages from 
8 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

1964–2007 was 0.21, 0.61, and 1.10 million acre-feet respectively. Annual flow from 2007 streamflow record was 0.16, 

0.51, and 1.09 million acre-feet respectively. 

Stormflow events during the study period are defined by 

peak-streamflow-recurrence interval (Rasmussen and Perry, 

2000; Perry and others, 2004). Polynomial relations among 2-, 

5-, 10-, 25-, 50-, and 100-year streamflow recurrence interval 

and peak streamflow were calculated to estimate peak-streamflow recurrence for individual storm events observed during 

the study period. Although the accuracy of extrapolating these 

relations is undefined between estimated points, relations are 

established as a general reference to compare storm size in 

and among monitoring sites. Storms were not defined by peak 

streamflow recurrence interval at the Burlington site because 

of streamflow regulation by John Redmond Reservoir. 

Nine storms were observed from February 21, 2007 

through February 21, 2008 (fig. 4). Stormflow periods were 

approximated from the first rise in streamflow (after a period 

of precipitation) until streamflow approximated base-flow 

conditions prior to the storm. Stormflow at the Americus 

and Plymouth gages included releases from Council Grove 

Lake (based on 15-minute USGS stream-gage data at the 

Neosho River near Council Grove, KS; figs. 1, 4) and Marion 

Reservoir (based on 15-minute USGS stream-gage data at 

the North Cottonwood River near Marion Reservoir, KS; 

fig. 1). Delineated stormflows contributed 86 (Americus) 

and 81 (Plymouth) percent of total streamflow, and occurred 

during 25 (Americus) and 27 (Plymouth) percent of the study 

period. The largest storm at Americus and Plymouth occurred 

from May 2 to 23, 2007, had a peak-streamflow recurrence of 

about once every 4.6–4.9 years (or an estimated annual peakstreamflow probability of about 20 percent), and contributed 

36 (Americus) and 31 percent (Plymouth) of the total streamflow (fig. 4). 

2.5

3.0

3.5

4.0

0

0.5

1.0

1.5

2.0

1964196519661967196819691970

1971

197219731974197519761977197819791980

1981

198219831984198519861987198819891990

1991

199219931994199519961997199819992000

2001

200220032004200520062007

MILLIONS OF ACRE-FEET 

Neosho River near Americus

Cottonwood River near Plymouth

Neosho River at Burlington

Median annual 

streamflow at 

Burlington 1.10 

million acre feet

Median annual 

streamflow at

Plymouth 0.61 

million acre feet

Median annual 

streamflow at 

Americus 0.21 

million acre feet

Figure 3. Annual flow at John Redmond sites, 1964–2007.
Characterization of Sediment Loading to and from John Redmond Reservoir 9

The magnitude and duration of streamflow at Burlington 

is controlled by the outflow from John Redmond Reservoir. 

Nine separate outflow events were delineated (fig. 4) that contributed 97 percent of the total streamflow volume observed 

at the site. The largest outflow event (in terms of volume) 

occurred from May 11 to June 2, 2007, and contributed 26 percent of total streamflow observed during the period of study. 

Total flow computed from February 21, 2007–2008, 

(based on 15-minute streamflow data) was 0.20 million 

acre-feet (Americus), 0.60 million acre-feet (Plymouth), and 

1.09 million acre-feet (Burlington). Total streamflow from 

Council Grove Lake was 0.11 million acre-feet, 55 percent 

of the total streamflow at Americus. Total streamflow from 

Marion Reservoir was 0.04 million acre-feet, 7 percent of 

total streamflow at Plymouth. Streamflow yield (flow volume/drainage area) was calculated for the regulated drainage area upstream from Council Grove Lake and Marion 

Reservoir (U.S Army Corps of Engineers, 2008) and for the 

unregulated drainage area by subtracting reservoir outflows 

from total streamflow at gaged sites during the period of 

record. Streamflow yield upstream from Council Grove Lake 

was 530 acre-ft/mi2 and was 440 acre-ft/mi2 upstream from 

Marion Reservoir. After subtracting outflow from reservoirs, 

streamflow yield from the unregulated watershed upstream 

from Americus was 250 acre-feet/mi2, and 370 acre-feet/mi2

from the unregulated drainage area upstream from Plymouth. 

Including discharge from John Redmond Reservoir, streamflow yield was 360 acre-feet/ mi2

 at Burlington. 

Duration curves are shown to compare the distribution 

of streamflow values at each site (fig. 5). Streamflow control 

and release from John Redmond decreased peak flow values 

(0–5 percent exceedence) and increased the duration of high 

flow (10–40 percent exceedence) at Burlington relative to 

upstream sites. A larger percentage of watershed regulation 

upstream from Americus (by Council Grove Lake) decreased 

peak streamflow (0.5–4 percent exceedence) at Americus relative to Plymouth.

Regression Models

Turbidity-sensor response has been shown to increase as 

particle-size composition of suspended-sediment decreases 

(Downing, 2006). Turbidity has been used to compute 

suspended-sediment concentration in Kansas streams in which 

silt and clay compose the majority of suspended-sediment 

(Christensen and others, 2000; Rasmussen and others, 2005). 

The diameter of suspended sediment (by weight) less than 

100, 63, 31, 16, 8, 4, and 2 micrometers (μm) was analyzed 

in selected samples collected during high flow (table 3). Silt 

and clay (<63 μm) composed greater than 89 percent of sediment concentration (by weight) for all study-area samples 

(table 3). Clay-sized particles (<4 μm, Guy, 1969) comprised 

44 to 68 percent of selected sediment-samples by weight; 

whereas silt-sized particles (4–63 μm, Guy, 1969) composed 

30 to 52 percent of selected sediment samples. The preponderance of clay and silt-sized particles during high flow (when 

large-sized grain sizes are most readily transported) indicate 

that optical sensors are appropriate to compute suspendedsediment concentration.

Regression models were developed to estimate continuous (15-minute) SSC using turbidity measurements (table 4, 

fig. 6). Models developed to compute suspended-sediment 

concentration for these sites are based on one year of data, 

and can continue to be refined as additional samples are collected through September 2009. After log-transformation, 

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Feb. 21

Mar.18

Apr. 12

May 07

June 01

June 26

July 21

Aug. 15

Sept. 09

Sept. 04

Oct. 29

Nov. 23

Dec. 18

Jan. 12

Feb. 06

(C) Neosho River at Burlington (fig. 1)

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Neosho River near Americus

Outflow from Council Grove Lake

Storm event number

0

5,000

10,000

15,000

20,000

25,000

STREAMFLOW, CUBIC FEET PER SECOND

(B) Cottonwood River near Plymouth and outflow 

 from Marion Reservoir (fig. 1)

2 1

3

3

4

5 6 7 8

9

2

1

3

3

4

5

6

7

8

9

1 2

3

3

4

5

6

7 8

9

Cottonwood River near Plymouth

Outflow from Marion Reservoir

Storm event number

Neosho River at Burlington

Storm event number

2007 2008

(A) Neosho River near Americus and outflow from

 Council Grove Reservoir (fig. 1)

Figure 4. Time-series streamflow values and storms delineated 

by number, John Redmond sites, February 2007–2008.
10 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

regression residuals approximated normality and did not 

indicate consistent bias around the regression fit (fig. 6). One 

outlier was omitted from SOLITAX/SSC models at Americus because the value had a small SSC value, and biased 

the slope of regression models at high SSC values (when 

the SOLITAX is primarily used to estimate SSC). Turbidity explained 94 to 98 percent of the variability in SSC from 

in-stream samples (based on the coefficient of determination, 

R2; table 4). YSI/SSC models at Americus and Plymouth had 

similar slopes (1.004 and 1.005 respectively) and y-intercept 

values (0.38 and 0.35 respectively) indicating that suspendedsediment size and color (the primary factors affecting these 

models) were similar among sampling sites. Burlington has 

the fewest samples (9) but also had less than 10 percent of 

the range in sediment concentration compared to inflow sites 

(table 4). 

Stormflow Effects on Sediment Loading

Nine storms observed during the study period contributed 

nearly the entire suspended-sediment load to John Redmond 

Reservoir (table 5). At Americus, 86 percent of total streamflow and 99 percent of sediment load was contributed by 

9 storms (which occurred 25 percent of the time). At Plymouth, 81 percent of total streamflow and 98 percent of the sediment load were contributed by storms (which occurred 27 percent of the time). Releases from John Redmond in excess of 

base flow occurred 50 percent of the time and contributed 

97 percent of the streamflow and sediment load observed at 

Burlington. The largest stormflow [May 2–23, 2007; estimated peak-streamflow recurrence interval of 4.6–4.9 years 

(or an annual peak-streamflow probability of about 20 percent; table 5)] contributed the most suspended sediment past 

1,000

10,000

100,000

1.0

10

100

STREAMFLOW, IN CUBIC FEET PER SECOND (ft3/s) 

Streamflow at 10 percent:

Americus, 769 ft3

/s

Plymouth, 1,820 ft3

/s

Burlington, 3,980 ft3

/s

Streamflow at 

 5 percent:

Americus, 1,570 ft3

/s

Plymouth, 3,280 ft3

/s

Burlington, 6,390 ft3

/s

Streamflow at 25 percent:

Americus, 152 ft3

/s

Plymouth, 528 ft3

/s

Burlington, 1,910 ft3

/s

Streamflow at 50 percent:

Americus, 35 ft3

/s

Plymouth, 238 ft3

/s

Burlington, 395 ft3

/s

Streamflow at 75 percent:

Americus, 23 ft3

/s

Plymouth, 99 ft3

/s

Burlington, 44 ft3

/s

Streamflow at 95 percent:

Americus, 15 ft3

/s

Plymouth, 47 ft3

/s

Burlington, 29 ft3

/s

Streamflow at 90 percent:

Americus, 16 ft3

/s

Plymouth, 59 ft3

/s

Burlington, 31 ft3

/s

Streamflow at 

 99 percent:

Americus, 9.4 ft3

/s

Plymouth, 43 ft3

/s

Burlington, 26 ft3

/s

0 10 20 30 40 50 60 70 80 90 100

FREQUENCY OF EXCEEDANCE, IN PERCENT

Streamflow at 1 percent:

Americus, 2,470 ft3

/s

Plymouth, 12,120 ft3

/s

Burlington, 11,650 ft3

/s

Neosho River near Americus

Cottonwood River near Plymouth

Neosho River at Burlington

Figure 5. Streamflow duration curves at John Redmond sites, February 2007–2008.
Characterization of Sediment Loading to and from John Redmond Reservoir 11

Table 3. Suspended-sediment concentration, percent silt/clay (<63 μm diameter), and grain-size distribution from discrete samples 

collected from John Redmond sites, February 2007–2008.

[<, less than, μm, micrometers; mg/L, milligrams per liter; FNU, formazin nephelometric units; ft3/s, cubic feet per second; --, not applicable; Max, sensor 

truncated]

Sample date

Suspended 

sediment 

concentration (mg/L)

Insitu 

turbidity 

(FNU)

Insitu 

SOLITAX 

(estimated 

mg/L)

Streamflow 

(ft3/s)

Percent of sediment (by weight) less than specified diameter

 < 100 μm < 63 μm < 31 μm < 16 μm < 8 μm < 4 μm < 2 μm

Neosho River near Americus

03/26/07 26 8 -- 20 92

03/30/07 76 20 8 110 93

03/31/07 1,880 620 1,280 1,210 100

03/31/07 1,940 940 2,160 1,710 99

04/02/07 790 280 680 1,340 99

04/15/07 2,150 770 1,520 2,760 100 96 86 58 45 44 40

04/16/07 820 270 640 430 97

04/17/07 360 150 320 810 99

04/20/07 220 100 160 1,070 99

05/07/07 2,070 940 1,920 6,090 100 94 87 67 61 56 51

05/08/07 480 280 360 6,600 98

07/17/07 19 36 40 36 97

Cottonwood River near Plymouth

03/26/07 78 20 -- 48 95

03/30/07 110 38 40 61 90

03/30/07 1,010 260 480 190 99

03/31/07 1,640 Max 1,520 4,510 99

03/31/07 1,420 950 1,480 4,180 99

04/02/07 350 140 280 840 98

04/15/07 730 300 560 4,110 95

04/16/07 1,200 490 840 3,700 98

04/17/07 620 330 600 1,780 98

04/20/07 200 73 160 510 89

05/07/07 1,960 Max 1,760 17,800 100 98 94 79 71 68 63

05/08/07 770 440 -- 22,400 96

05/24/07 3,960 Max 2,280 5,200 99 99 85 67 59 53 50

05/24/07 3,080 Max 2,040 5,490 100 99 90 73 58 56 50

07/02/07 360 150 -- 4,030 99

07/18/07 130 34 80 260 95

10/18/07 310 170 -- 810 99

Neosho River at Burlington

03/26/07 20 15 45 98

03/30/07 83 77 220 97

03/31/07 96 93 180 98

04/12/07 190 130 1,790 92

04/20/07 70 54 2,840 90

06/22/07 47 39 6,570 98

07/19/07 48 24 4,230 96

09/21/07 57 40 390 94
12 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008 Table 4. Regression models and statistics for estimating suspended-sediment concentration (SSC) from turbidity values at study area sites, February 2007–2008. [SSC, suspended-sediment concentration; R2, coefficient of determination; MSE, mean-squared error; YSI, Yellow Springs Instruments; mg/L, milligrams per liter; Turb, turbidity in formazin nephelometric units; Sol, SOLITAX in estimated milligrams per liter] Site name (fig. 1) Regression relation Duan bias correction1 R2 MSE Discrete sample results Number of samples Range in response variable Range in SSC (mg/L) Mean Median Standard deviation Suspended-sediment concentration and YSI model 6136 turbidity sensor Neosho River near Americus Log(SSC) = 1.004log(YSI)+.38 1.04 0.97 0.02 12 8.5–940 19–2,150 900 630 860 Cottonwood River near Plymouth Log(SSC) = 1.005log(YSI)+.35 1.01 0.98 0.004 13 20–680 78–1,420 560 360 440 Neosho River at Burlington Log(SSC) = 0.899log(YSI)+.30 1.01 0.94 0.007 9 15–160 20–200 90 70 63 Suspended-sediment concentration and SOLITAX turbidity sensor Neosho River near Americus Log(SSC) = 0.917log(Sol)+.30 1.01 0.96 0.01 7 8–2,190 19–2,150 900 630 860 Cottonwood River near Plymouth Log(SSC) = 0.902log(Sol)+.38 1.02 0.96 0.01 12 69–3,060 78–1,960 660 493 560

1(Duan, 1983).
Characterization of Sediment Loading to and from John Redmond Reservoir 13

10

100

1,000

10,000

10

100

1,000

10,000

10

100

1,000

10,000

10

100

1,000

10,000

10

100

1,000

10,000

1 10 100 1,000 10,000 1 10 100 1,000 10,000

TURBIDITY (TURB), IN FORMAZIN NEPHELOMETRIC UNITS

Neosho River near Americus (fig. 1) Neosho River near Americus (fig. 1)

Regression fit

90-percent prediction 

 interval

Regression fit

90-percent prediction 

 interval

Regression fit

90-percent prediction 

 interval

Regression fit

90-percent prediction 

 interval

10 100 1,000 10,000

ESTIMATED SOLITAX (SOL), IN MILLIGRAMS PER LITER 

10 100 1,000 10,000

SUSPENDED SEDIMENT CONCENTRATION (SSC), IN MILLIGRAMS PER LITER 

Cottonwood River near Plymouth (fig. 1) Cottonwood River near Plymouth (fig. 1)

10 100 1,000 10,000

Neosho River at Burlington (fig. 1)

Log(SSC) = 1.004log(Turb) + 0.38

R2

= 0.97

Log(SSC) = 0.917log(Sol) + 0.30

R2

= 0.96

Log(SSC) = 1.005log(Turb) + 0.35

R2

= 0.98

Log(SSC) = .902log(Sol) + 0.38

R2

= 0.96

Log(SSC) = .899log(Turb) + 0.30

R2

= 0.94

Regression fit

90-percent prediction 

 interval

Figure 6. Regression models between optical sensors and suspended-sediment concentration at study area sites, February 2007–2008.
14 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

Table 5. Dates, streamflow, and suspended sediment loading of stormflow for study period at John Redmond sites, February 

2007–2008.

[tons/mi2, tons per aquare mile; --, no data]

Storm 

designation Start date End date

Peak 

streamflow 

recurrence 

interval 

(years)

Total streamflow 

(acre-feet)

Percent of 

total streamflow

Turbiditycomputed 

suspendedsediment load 

(tons)

Percent of total 

suspendedsediment load

Suspendedsediment yield 

of total drainage area 

(tons/mi2)

Neosho River near Americus

1 03/30/07 04/07/07 0.4 13,200 6.7 18,800 9.1 30

2 04/13/07 04/22/07 .5 15,900 8.1 12,900 6.2 21

3 05/06/07 05/23/07 4.6 70,500 36 85,600 41 140

4 05/24/07 06/09/07 .6 32,700 17 48,400 23 78

5 06/12/07 06/24/07 .1 5,890 3.0 1,820 .9 2.9

6 06/28/07 07/04/07 .1 3,330 1.7 1,010 .5 1.6

7 12/11/07 12/16/07 .1 2,110 1.1 660 .3 1.1

8 01/05/08 01/16/08 .1 7,910 4.0 1,120 .5 1.8

1

9 02/16/08 02/21/08 1.1 18,600 9.4 34,800 16.8 56

Entire 

period of 

record

02/21/07 02/21/08 -- 197,100 100 207,500 100 330

Cottonwood River near Plymouth

1 03/30/07 04/07/07 .3 14,500 2.4 30,400 4.9 18

2 04/13/07 04/25/07 .2 27,900 4.7 31,500 5.1 18

3 05/02/07 05/21/07 4.9 182,900 31 219,900 36 130

4 05/24/07 06/09/07 .6 102,700 17 120,200 19 69

5 06/28/07 07/09/07 1.5 63,800 11 69,500 11 40

6 07/29/07 08/08/07 .1 17,300 2.9 20,700 3.3 12

7 10/14/07 10/23/07 .03 10,800 1.8 8,940 1.4 5.1

8 12/10/07 12/17/07 .1 14,700 2.5 11,900 1.9 6.8

1

9 02/16/08 02/21/08 1.0 50,100 8.4 96,400 16 55

Entire 

period of 

record

02/21/07 02/21/08 -- 598,800 100 620,100 100 360

Neosho River at Burlington

1 03/29/07 04/15/07 -- 49,900 4.6 8,580 8.5 2.8

2 04/16/07 05/05/07 -- 76,200 7.0 11,100 11.0 3.6

3 05/11/07 06/02/07 -- 288,000 26 32,400 32 11

4 06/03/07 06/12/07 -- 102,700 9.4 8,300 8.2 2.7

5 06/15/07 07/03/07 -- 149,600 14 12,700 13 4.2

6 07/16/07 08/23/07 -- 240,800 22 12,100 12 4.0

7 10/18/07 10/23/07 -- 11,200 1.0 2,200 2.2 .7

8 12/26/07 02/17/08 -- 110,200 10 6,250 6.2 2.1

1

9 02/19/08 02/21/08 -- 26,600 2.4 3,750 3.7 1.2

Entire 

period of 

record

02/21/07 02/21/08 -- 1,091,000 100 100,700 100 33.1

1

Storm ongoing at the end of study period.
Characterization of Sediment Loading to and from John Redmond Reservoir 15

monitoring sites (41 percent at Americus, 36 percent at Plymouth). Sediment yields were larger at Plymouth (360 tons/mi2

), 

in part because of increased total and unregulated drainage 

area compared with Americus (330 tons/mi2). Suspended-sediment load (100,700 tons) and yield (33 tons/mi2

) at the Neosho 

River at Burlington is substantially smaller than upstream sites 

because of the settling of sediment in (or upstream from) John 

Redmond Reservoir (table 5). 

Total suspended-sediment load and streamflow volume are compared for the nine storms/flood control releases 

observed at monitoring sites (fig. 7), to determine sediment 

loading among different-sized storms. Best fit lines are shown 

to provide a frame of reference for comparison of sediment/

streamflow relations; additional events need to be measured to 

verify potential relations. Sediment load generally increased 

in a linear fashion with increases in streamflow volume at all 

three monitoring sites. Flood-control releases at Burlington 

had much smaller sediment loading per streamflow volume 

because of sediment trapping in John Redmond Reservoir. The 

largest stormflow (storm 3; fig. 7, table 5) at Americus and 

Plymouth did not indicate decreased sediment supply relative 

to other storms despite the large volume of streamflow. Larger 

sediment loading per streamflow volume during storm 9 at 

upstream sites was partially because values had not returned to 

base flow by the end of the study period. 

Duration curves were calculated for 30-minute computations of suspended-sediment load (SSL) at study area sites. 

Sediment trapped in John Redmond substantially decreased 

maximum (0–5 percent exceedence) sediment loads at Burlington relative to upstream sites (fig. 8). Whereas, the most 

(>50 percent) sediment was transported during 0.9 percent of 

the study period (~3.1 days) at Americus, and 1.5 percent of 

the time (~5.7 days) at Plymouth, the most of sediment was 

transported in 8.5 percent of the time (~31 days) at Burlington. 

Council Grove Lake trapped a larger percentage of sediment 

upstream from the Americus gage than did Marion Reservoir, 

causing smaller duration of high sediment loading conditions (>100 pounds per second) relative to Plymouth. Prolonged, large releases from John Redmond resulted in longer 

duration of sediment loading more than 1 pound per second 

at Burlington.

Effects of Upstream Reservoirs on Sediment 

Loading

The vast majority of water released from Council Grove 

Lake and Marion Reservoir was contributed by a few large 

releases. These releases transported additional sediment past 

downstream monitoring sites, increasing observed sediment 

loads. In order to compare sediment loading among sites, 

and to estimate sediment loading from ungaged parts of the 

John Redmond watershed, sediment loads were distinguished 

between regulated and unregulated parts of upstream watersheds. Sediment originating from impoundment outflows and 

from unregulated watersheds is distinguished using methods 

described in “Computation of sediment concentrations, loads, 

and yields.” 

About 6 percent (11,700 tons) of the 207,500 tons of sediment transported past Americus, originate in outflows from 

Council Grove Lake (table 6). About 0.6 percent (4,000 tons) 

of the 620,100 tons of sediment transported past Plymouth 

originate in outflows from Marion Reservoir. After subtraction 

of sediment loading from upstream reservoirs, sediment yield 

estimates for the unregulated watershed upstream from monitoring sites are 530 tons/mi2

 at Americus and 400 tons/mi2

at Plymouth. 

Reservoir releases transport sediment from both the 

reservoir and the downstream channel. Because flood-control 

releases from Council Grove Lake and Marion Reservoir 

commonly occurred after large storms or during base flow, 

resultant increases in sediment loading could be estimated at 

downstream monitoring sites (fig. 9). Continuous streamflow 

and sediment loading values before and after reservoir releases 

were used to create an exponential fit to estimate hypothetical 

streamflow and sediment loading without upstream reservoir 

releases. These estimates were subtracted from observed values to estimate total streamflow and sediment load contributed 

by upstream impoundments to downstream monitoring sites 

(fig. 9, table 6). One outflow at Plymouth was estimated by 

using only streamflow and sediment loading values observed 

prior to a release from Marion Reservoir, because a storm 

increased streamflow and sediment loading before the Cottonwood River returned to base flow. 

Streamflow measured from upstream reservoir releases 

are compared with values estimated at downstream sites 

to evaluate the accuracy of methods used to estimate total 

sediment loading from large reservoir releases. Streamflow 

from the seven flood-control releases from Council Grove 

Lake (92,900 acre-feet) were larger than those estimated at 

Americus (75,400 acre-ft), partially because the release from 

February 19, 2008, had not yet reached Americus by the end 

of the study period. Outflows from the remaining six releases 

(87,500 acre-ft) were slightly larger than those estimated at 

Americus (74,200 acre-ft). Outflows from the three large 

releases from Marion Reservoir (over two storms) were 

40,100 acre-ft, compared to an estimate of 25,700 acre-ft at 

Plymouth. Smaller estimates of streamflow volume at downstream monitoring sites are likely because of dispersion of the 

release and (or) loss of flow to ground water in the intermediate stream channel. 

 Reservoir releases from Council Grove Lake are estimated to transport 51,000 tons of sediment past the monitoring 

site near Americus. Subtraction of the estimated 11,700 tons 

of sediment transported directly from the Council Grove 

outflow results in 39,300 tons of sediment estimated to have 

been transported from the stream channel of the Neosho 

River by reservoir releases (table 6). Outflows from Marion 

Reservoir are estimated to have transported 18,200 tons of 

sediment past Plymouth. After subtraction of the estimated 

4,000 tons that originated from the outflow, 14,200 tons of 

sediment are estimated to have been transported from the 
16 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

Cottonwood River channel by reservoir releases. Evidence 

that channel sediments are transported by reservoir releases 

was obtained by collection of turbidity readings at the Council 

Grove Lake outflow on February 20, 2008. Turbidity readings from the outflow were 17 formazin nephelometric units 

(FNU) at 1,150 cubic feet per second of streamflow. Sixteen 

hours later (approximate travel time of the release) readings at 

Americus were about 110 FNU at 1,420 cubic feet per second. 

The large increase in turbidity and relatively small increase in 

flow between the two sites indicate that substantial sediment 

had been transported from the Neosho River channel by the 

reservoir release. 

Tributaries contribute streamflow and sediment to 

the mainstem of the Cottonwood and Neosho Rivers during storms. Immediately downstream from impoundments, 

tributary flows are relatively small compared to the historic, 

unregulated floods that formed the main channel (Morris and 

Fan, 1997). The velocity of small tributary flows decrease 

as it enters the regulated, low streamflow of the main channel, allowing time for sediments to fall to the streambed. 

Higher-energy streamflows released from upstream reservoirs 

likely transport these sediments downstream. Thus, sediment 

transported by reservoir flood-control releases may have been 

transported by runoff events without the presence of the dam. 

Because of this, sediment transported from stream channels 

downstream from dams are considered to have originated from 

the unregulated drainage area.

Trapping Efficiency and Storage Loss

Sediment yields from the unregulated drainages upstream 

from Americus and Plymouth were used to estimate sediment 

loading from the ungaged drainage upstream from John Redmond Reservoir according to methods described in “Computation of sediment concentrations, loads, and yields.” About 

1,120,000 tons of sediment entered John Redmond from 

February 21, 2007, through February 21, 2008. Compared 

with 100,700 tons of sediment transported past Burlington, 

a trapping efficiency of 91.0 percent was calculated for John 

Redmond during the study period (fig. 10).

150,000 

200,000 

250,000 

3

0 

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

50,000 

100,000 

SEDIMENT LOAD, IN TONS 

TOTAL STREAMFLOW VOLUME, IN ACRE-FEET

4

9

5

2 8

6

3

2

1

4

4

9 3

6 5 8 4

2 1

Neosho River near Americus

Cottonwood River near Plymouth

Neosho River at Burlington

Storm event (table 5)

Figure 7. Relation between sediment loading and streamflow volume during stormflow events at John Redmond sites, February 2007–

2008.
Characterization of Sediment Loading to and from John Redmond Reservoir 17

Potential sources of error in this estimate include the 

settling of suspended sediment prior to entry to the John 

Redmond Reservoir, error in estimation methods, and transport of sediment from the stream channel between the John 

Redmond outflow and the Burlington site. The large logjam 

present upstream may promote settling of sediment prior to 

entry to the reservoir (U.S. Army Corps of Engineers, 2005). 

Error is present in estimates of sediment yield upstream from, 

and sediment trapping efficiency of Council Grove Lake and 

Marion Reservoir, as well as in estimates of sediment loading 

from ungaged parts of the drainage. However, because Council Grove Lake and Marion Reservoir trap most of the incoming sediment from upstream drainages, changes in estimates 

of sediment yield and trapping efficiency do not substantially 

change estimates of loading to John Redmond. Additionally, because 78 percent of the drainage upstream from John 

Redmond is gaged, variation in sediment yields used to 

estimate the ungaged portion of the drainage do not cause 

substantial differences in loading to the reservoir. Whereas 

sediment may be transported from the channel between John 

Redmond and Burlington, instantaneous comparisons of 

turbidity between the John Redmond outflow and Burlington 

were similar (within 20 percent) during observations on February 8 and 28, 2008.

Estimates of the bulk density in small Kansas impoundments have ranged from about 20 to 70 lbs/ft3

 (Juracek, 2004); 

mean bulk density in Cheney Reservoir was 62 lbs/ft3 (Mau, 

2001). Sediment loading into John Redmond was divided 

by bulk densities ranging from 20 to 70 lbs/ft3 to estimate 

sedimentation rates to John Redmond Reservoir during the 

study period (table 7). Sediment volume accumulated from 

February 21, 2007, through February 21, 2008, ranged from 

2,340 acre-ft (20 lbs/ft3) to 670 acre-ft (70 lbs/ft3). Calculated 

sedimentation rates were larger than the designed sedimentation rate (404 acre-ft/year; Kansas Water Office, 2008b) 

during a study period with about median historical streamflow. 

Estimates of lake surface area and volume were obtained from 

a 2007 bathymetric survey (Kansas Biological Survey, 2007) 

10

100

1,000

10,000

0.001

0.01

0.1

1.0

SUSPENDNED-SEDIMENT LOAD, IN POUNDS PER SECOND

0 10 20 30 40 50 60 70 80 90 100

FREQUENCY OF EXCEEDANCE, IN PERCENT

Suspended sediment 

 load at 1 percent:

Americus, 290

Plymouth, 900

Burlington, 63

Suspended sediment 

 load at 10 percent:

Americus, 16

Plymouth, 46

Burlington, 17

Suspended sediment 

 load at 50 percent:

Americus, 0.09

Plymouth, 0.62

Burlington, 0.93 Suspended sediment 

 load at 90 percent:

Americus, 0.02

Plymouth, 0.14

Burlington, 0.05

Suspended sediment 

 load at 99 percent:

Americus, 0.01

Plymouth, 0.02

Burlington, 0.03

Suspended sediment 

 load at 75 percent:

Americus, 0.03

Plymouth, 0.22

Burlington, 0.09

Suspended sediment 

 load at 95 percent:

Americus, 0.02

Plymouth, 0.08

Burlington, 0.04

Suspended sediment 

 load at 25 percent:

Americus, 0.96

Plymouth, 3.4

Burlington, 8.3

Suspended sediment 

 load at 5 percent:

Americus, 45

Plymouth, 180

Burlington, 24

Neosho River near Americus

Cottonwood River near Plymouth

Neosho River at Burlington

Figure 8. Suspended-sediment load duration curves at John Redmond sites, February 2007–2008.
18 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008 Table 6. Streamflow, sediment load, and sediment yield from regulated and unregulated drainage areas at monitoring sites upstream from John Redmond Reservoir, February 2007–08. [tons/mi2, tons per aquare mile] Site name (fig. 1) Streamflow Sediment load Sediment yield Total stream- flow volume (acre-feet) Total streamflow from reservoir releases (acre-feet) Total streamflow from large, flood control releases (acre-feet) Total suspended- sediment load (tons) Suspended-sediment load originating from reservoir release (tons) Suspended- sediment load transported from down- stream channel by res- ervoir releases (tons) Sediment yield from total upstream watershed (tons/mi2

)

Sediment yield 

from unregulated watershed 

(tons/mi2

)

Neosho River near 

Americus

 197,100 105,400 92,900 207,500 11,700 39,300 330 530

Cottonwood River 

near Plymouth

 598,800 44,100 40,100 620,100 4,000 14,200 360 400 
Characterization of Sediment Loading to and from John Redmond Reservoir 19

to estimate storage lost and depth of sediment accumulation during the period of study. Approximate lake volume at 

the elevation (1,038.5 ft) nearest the top of the multipurpose 

pool (1,039 ft) was 47,284 acre-feet, with a surface area of 

8,368 acres (Kansas Biological Survey, 2007). A range of bulk 

density values from 20 to 70 lbs/ft3, was used to estimate storage lost that ranged from 5.0 to 1.4 percent, with an average 

sediment deposition of 3.4 to 1.0 inches (table 7).

Comparison to Historical Data

Historically, 497 SSC samples were collected by the 

USGS from the three sampling sites from 1944 to 1992. 

Regression models were developed between streamflow and 

suspended-sediment load for historic samples, and applied 

to continuous (15-minute) streamflow values recorded from 

February 21, 2007, through February 21, 2008. Historic 

SSC samples were only considered after gates had closed at 

upstream impoundments (October 1964 at Americus, February 1968 at Plymouth, and September 1964 at Burlington) 

and only if data were collected at least annually (table 8). 

Total sediment loads are calculated by using historic streamflow/sediment loading relations to estimate the magnitude 

of historic sediment loading expected given the flow regime 

observed during the current study period. Percentage root 

mean square error, 90-, and 99-percent confidence intervals 

of total load estimates are defined for historic streamflow/

0

50

100

150

200

250

300

350

400

0

500

1,000

1,500

2,000

2,500

3,000

INSTANTANEOUS SUSPENDED-SEDIMENT LOAD,

IN POUNDS PER SECOND

STREAMFLOW, IN CUBIC FEET PER SECOND AND SUSPENDED

SEDIMENT CONCENTRATION, IN MILLIGRAMS PER LITER 

0

200

400

600

800

1,000

1,200

0 100 200 300 400 500 600

STREAMFLOW (Q), IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

0 100 200 300 400 500 600

INSTANTANEOUS SUSPENDED-SEDIMENT

LOAD (SSL), IN TONS

NUMBER OF VALUES (N) NUMBER OF VALUES (N)

8 10 12 14 16 18

APRIL, 2007

20 22 24 26

Streamflow and sediment

load from release from 

Council Grove Reservoir 

Streamflow and sediment load 

rainfall-runoff, estimated 9,380 

tons of sediment transported

Q = 303.21e-0.001N SSL = 10.446e-0.003N

Streamflow

Suspended sediment concentration

Instantaneous suspended sediment load

Estimated 6,530 acre-feet of 

streamflow (8,600 acre-ft 

released from Council 

Grove Reservoir)

Estimated 2,360 tons of 

sediment contributed by 

Council Grove Reservoir

release

Figure 9. Estimation of streamflow and sediment loading originating from Council Grove Reservoir at the Neosho River near 

Americus, April 8–26, 2007.
20 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

sediment loading estimates and turbidity/SSC relations using 

error approximation methodology described in Gilroy and 

others (1990). If differences in total sediment loads calculated 

between historic and current relations exceed 90-percent 

confidence intervals, then the presumption (with 90-percent 

confidence) is that differences in sediment loads in observed 

streamflow from February 2007–2008 are due to factors other 

than error in estimation techniques. 

Streamflow/sediment load relations at Americus were 

underrepresented by a single log-linear fit at large streamflow values. Two log-linear relations were developed, one 

representing low flow (<279 cubic feet per second) and one 

representing high flow (>279 cubic feet per second) using 

methods described in Glysson (1987). Relations at Plymouth 

and Burlington did not have identifiable bias around a single 

log-linear fit, and thus were represented by a single relation. 

Streamflow explained 81 to 88 percent of the variability in 

historic SSC samples (based on R2, fig. 11). 

Historic and current estimates of sediment loading at 

Americus and Plymouth were within the 90-percent confidence intervals of total load estimates, indicating no significant difference between historic and current study periods. 

Differences in sediment loading estimates at Burlington were 

outside of 99-percent confidence intervals indicating that 

changes in sediment loading have occurred between 1964–

1978 and 2007–2008. Ninety-percent confidence intervals of 

total sediment loads calculated by using historic streamflow/

sediment load relations was 7 to 21 times larger than turbidity 

estimated sediment loading at all sites (table 9). 

Channel beds and banks have been documented to scour 

after upstream impoundments are constructed (Morris and 

Fan, 1997). Sediments in the streambed and channel banks 

directly downstream from John Redmond may have been 

transported during high-flow releases immediately after gates 

were closed, and are no longer available for transport because 

the downstream channel has adjusted to accommodate the 

stream-power of large releases. An alternative explanation 

is that the logjam upstream from John Redmond is trapping 

more sediment than during historic conditions, allowing less 

sediment to move through the outflow. Additional sediment 

sampling and continuous sediment monitoring of storms can 

be used to refine techniques to assess potential changes in 

sediment transport at monitoring sites. 

Summary and Conclusions

Continuous turbidity sensors were used to characterize suspended sediment-loading to and from John Redmond 

Reservoir from February 21, 2007, to February 21, 2008. 

Sensors were installed at U.S. Geological Survey stream gage 

sites on the Neosho River near Americus and the Cottonwood 

River near Plymouth that monitor 78 percent of the watershed upstream from John Redmond Reservoir. Suspendedsediment concentrations and loads were monitored from the 

John Redmond outflow by sensor installation at a stream gage 

at the Neosho River at Burlington. Ordinary-least-squares 

regression equations were used to develop statistical relations 

between turbidity sensor measurements and in-stream samples 

of suspended-sediment concentration. Turbidity sensors 

explained 94 to 98 percent of the variability in suspendedsediment concentration from in-stream samples. Regression 

relations between turbidity sensors and suspended-sediment 

concentration were applied to continuous (15-minute) values 

of turbidity and streamflow to estimate sediment loading to 

and from John Redmond Reservoir. 

Stormflow contributed nearly all the suspendedsediment load observed at each site. Ninety-nine percent 

of the suspended-sediment load at the Neosho River near 

500,000

600,000

700,000

800,000

Approximate suspendedsediment trapping 

efficiency = 91.0 percent

0

100,000

200,000

300,000

400,000

SUSPENDED SEDIMENT LOAD, IN TONS

NEOSHO RIVER COTTONWOOD

RIVER 

NEOSHO RIVER AT 

BURLINGTON (ESTIMATE 

(ESTIMATE TO JOHN REDMOND) FROM JOHN REDMOND)

Figure 10. Approximate suspended-sediment load to and from 

John Redmond Reservoir, February 2007–2008.

Table 7. Estimate of storage lost in John Redmond Reservoir 

under varying estimates of bulk density, February 2007–08.

[Estimates from 1,020,000 tons of sediment retained, and storage volume 

and surface area at a lake elevation of 1,038.5 feet1; lbs/ft3, pounds per 

cubic foot]

Bulk density 

(lbs/ft3)

Volume of 

deposition 

(acre-feet)

Percentage 

of storage 

lost 

Mean depth 

of sediment 

accumulation 

(inches)

20 2,340 5.0 3.4

30 1,560 3.3 2.2

40 1,170 2.5 1.7

50 940 2.0 1.3

60 780 1.7 1.1

70 670 1.4 1.0

1

Kansas Biological Survey, 2007.
Characterization of Sediment Loading to and from John Redmond Reservoir 21

Table 8. Regression models and statistics for estimating suspended-sediment load (SSL) using historic (1964–1978) sediment and streamflow at study area sites, February 2007–2008.[SSL, suspended-sediment load; mg/L, milligrams per liter; R2, coefficient of determination; MSE, mean-square error; Q, streamflow, in cubic feet per second; SSC, suspended-sediment concentration; Q, streamflow in cubic feet per second]

Site name (fig. 1) Period of record Regression relation Duan bias correction1 R2 MSE Number of samples Range in Q Suspended-sediment concentration (mg/L) Range in SSC Mean Me- dian Standard deviation

Neosho River near 

Americus

1966–77 Q < 279: Log(SSL) = 1.1885log(Q) - 2.61 

Q>279: Log(SSL) = 1.9132log(Q) - 4.40

1.281.31

0.82

.78

0.084 

.11

8336

3–270 

290–4,030

10–300 

30–4,920

98

540

 90

270

60

870

Cottonwood River 

near Plymouth

1968–77 Log(SSL) = 1.465log(Q)-3.10 1.34 .87 .096 105 38–15,800 10–2,640 330 190 430

Neosho River at 

Burlington

1964–78 Log(SSL) = 1.282log(Q)-3.10 1.46 .88 .13 151 7–15,100 3–730 110 80 110

1(Duan, 1983).
22 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

Americus, and 98 percent of the suspended-sediment load at 

the Cottonwood River near Plymouth was transported by the 

nine storms observed during the study period (which occurred 

25–27 percent of the time). The largest storm (4.6–4.9 year 

peak-streamflow recurrence interval) occurred from May 2 to 

May 23, and accounted for 41 percent of the total sediment 

load at the Americus site and 36 percent of the total sediment 

load at the Plymouth site. Sediment loading at Burlington 

was primarily controlled by streamflow releases from John 

Redmond Reservoir. Ninety-seven percent of the sediment 

load at the Burlington site was contributed by the nine outflow 

releases (which occurred 50 percent of the time). 

Federal impoundments upstream from monitoring sites 

caused observable changes to streamflow and sediment loading at monitoring sites. The Cottonwood River near Plymouth 

had a larger suspended-sediment yield (360 tons/mi2) than at 

the Neosho River near Americus (330 tons/mi2) if sedimenttrapping effects from upstream impoundments are not considered. When estimates of sediment trapped by the upstream 

reservoirs was subtracted from loads computed at monitoring 

sites, the unregulated watershed upstream from the Neosho 

River near Americus had a larger suspended-sediment yield 

(530 tons/mi2) than upstream from the Cottonwood River near 

Plymouth (400 tons/mi2). Reservoir releases transport sediment from the main channel downstream from the outflow in 

addition to sediment transported directly from Council Grove 

Lake and Marion Reservoir. Larger, more frequent releases 

from Council Grove Lake transported about 39,300 tons of 

sediment from the main stem channel of the Neosho River, 

compared to 14,200 tons of sediment transported from the 

Cottonwood River by releases from Marion Reservoir. 

About 1,120,000 tons of suspended-sediment were transported to, and 100,700 tons were transported from John Redmond Reservoir, resulting in 91 percent trapping efficiency 

during the study period from February 21, 2007 to February 21, 2008. Based on estimates of bulk density ranging from 

20 to 70 lbs/ft3, 5.0 to 1.4 percent of the storage in the John 

Redmond conservation pool was lost during the study period, 

with an average deposition of 3.4 to 1.0 inches. 

Regression models were developed between streamflow 

and sediment loading data collected from 1964–1978 at the 

three monitoring sites. Models were applied to streamflow 

observed during the current study period, and summed to 

obtain an estimate of total sediment load. Error in computed 

total load was estimated to determine if differences in historic 

and current sediment loading computation methods were 

because of uncertainty or changes in sediment loading conditions at monitoring sites. Sediment loads computed at Americus and Plymouth were statistically indistinguishable; whereas 

loads between historic and current load estimates at Burlington 

1 10 100 1,000 10,000 100,000

INSTANTANEOUS SUSPENDED-SEDIMENT LOAD (SSL), IN POUNDS PER SECOND

STREAMFLOW (Q), IN CUBIC FEET PER SECOND (CFS)

0.01

0.1

1.0

10

100

1,000

10,000

0.001

0.01

0.1

1.0

10

100

1,000

10,000

0.01

0.001

0.1

1.0

10

100

1,000

 1964−78 relation:

Log SSL = 1.282(logQ) -3.10

R2 = 0.88

Duan’s bias correction = 1.46

1964−78

1968−77

1966−77

 1966−77 relation:

Streamflow less than 279 ft3/s:

Log SSL = 1.188(logQ) -2.61

R2 = 0.82

Duan's bias correction = 1.28

Log SSL = 1.913(logQ) - 4.40

R2 = 0.78

Duan's bias correction = 1.31

 1968−77 relation:

Log SSL = 1.465(logQ) -3.10

R2 = 0.87

Duan’s bias correction = 1.34

1 10 100 1,000 10,000

(A) Neosho River near Americus (fig. 1)

Regression fit

90-percent prediction interval

(B) Cottonwood River near Plymouth (fig. 1)

(C) Neosho River near Burlington (fig. 1)

Regression fit

90-percent prediction 

 interval

Regression fit

90-percent prediction interval

1 10 100 1,000 10,000 100,000

Figure 11. Relations between streamflow and suspendedsediment load (SSL) for historic sediment samples at study 

area sites.
References Cited 23

were larger than 99 percent confidence estimates. Significant differences in sediment loading at Burlington are either 

because of less sediment transported from the stream channel 

between the John Redmond outflow and the Burlington site, or 

improved trapping of sediment upstream from John Redmond 

Reservoir. Ninety-percent confidence intervals of streamflowderived estimates of sediment loading were 7 to 21 times that 

of turbidity-derived estimates of sediment loading. Additional 

sediment data collected through September 2009 can be used 

to refine regression models and trend analyses described in 

this report. 

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Table 9. Comparison of total sediment loads estimated from turbidity (2007–2008) and historic (1964–1978) streamflow measurements, 

February 2007–2008.

[+/-, plus or minus]

Site name

(fig. 1)

Turbidity derived estimates Historic streamflow-derived estimates

Estimated 

sediment 

load (tons)

Percentage 

root mean 

squared error

90-percent 

confidence 

interval

99-percent 

confidence 

interval

Estimated 

sediment 

load (tons)

Percentage 

root mean 

squared error

90-percent 

confidence 

interval

99-percent 

confidence 

interval

Neosho River 

near Americus

207,500 3.2 ± 14,430 ± 22,920 257,100 13.7

19.8

±102,400 ± 151,030

Cottonwood 

River near 

Plymouth

620,100 1.1 ± 14,900 ± 23,420 706,200 15.7 ± 208,900 ± 302,110

Neosho River at 

Burlington

100,730 2.4 ± 5,500 ± 8,290 291,600 19.7 ± 113,720 ± 164,480
24 Characterization of Suspended-Sediment Loading to and from John Redmond Reservoir, East-Central Kansas, 2007–2008

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Lee and others—Characterization of Suspended Sediment Loading to and from John Redmond Reservoir, 2007–2008—Scientific Investigations Report 2008–5123

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