U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5274

Revised August 2009

Prepared in cooperation with the

JOHNSON COUNTY STORMWATER MANAGEMENT PROGRAM

Bottom-Sediment Accumulation and Quality in Shawnee

Mission Lake, Johnson County, Kansas, 2006

Shawnee Mission

Lake

Shawnee Mission

Lake

1966

2006

Bottom-Sediment Accumulation and 

Quality in Shawnee Mission Lake, Johnson 

County, Kansas, 2006

By Casey J. Lee, Kyle E. Juracek, and Christopher C. Fuller

In cooperation with the Johnson County Stormwater Management Program

Scientific Investigations Report 2007–5274

Revised August 2009

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

Revised: 2009

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Lee, C.J., Juracek, K.E., and Fuller, C.C, 2007, Bottom-sediment accumulation and quality in Shawnee Mission Lake, 

Johnson County, Kansas, 2006: U.S. Geological Survey Scientific Investigations Report 2007–5274, 10 p. (Revised 

August 2009)
iii

Contents

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

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

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

Acknowledgements..............................................................................................................................1

Methods...........................................................................................................................................................2

Sample Collection and Laboratory Methods....................................................................................2

Quality Control.......................................................................................................................................3

Age and Accumulation Rates of Lake-Bottom Sediment........................................................................3

Nutrient and Trace Element Concentrations.............................................................................................8

Summary..........................................................................................................................................................8

References Cited..........................................................................................................................................10

Figures

1. Map showing urban development in and near the Shawnee Mission Lake watershed, 

Johnson County, Kansas, 2006 ...................................................................................................2

2. Photograph showing pontoon boat mounted with gravity corer used to collect bottom 

sediment cores from Shawnee Mission Lake, May and November 2006 ...........................3

3. Graph showing total precipitation and number of days in which greater than 1 inch of 

rainfall was recorded, Olathe, Kansas, 1960–2006..................................................................4

4. Graphs showing cesium-137 and excess lead-210 activity in relation to core depth and 

estimated year of deposition in Shawnee Mission Lake bottom sediment ........................7

5. Graphs showing selected nutrient and trace element profiles in bottom-sediment 

cores from three Johnson County lakes...................................................................................9

Tables

1. Concentrations of radionuclides, nutrients, and trace elements in core 1, Shawnee 

Mission Lake bottom sediment, Johnson County, Kansas, May 2006..................................6

2. Bulk density and concentrations of radionuclides in core 2, Shawnee Mission Lake 

bottom sediment, Johnson County, Kansas, November 2006................................................7
iv

Conversion Factors, Abbreviations, and Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

micron (μm) 0.00003937 inch (in.)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

Mass

gram (g) 0.002205 pound (lb)

Density

pound per cubic foot (lb/ft3) .01602 gram per cubic centimeter (g/cm3)

Rate

inch per year (in/yr) 2.54 centimeter per year (cm/yr)

Concentration

milligram per kilogram (mg/kg) 1.0 part per million (ppm)

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

Shawnee Mission Lake is an artificial impoundment 

central to Shawnee Mission Park, the largest public park in 

Johnson County, Kansas. The Shawnee Mission Lake watershed has remained relatively undeveloped since the completion of the dam in 1962. However, recent (1990–2006) urban 

development has been a cause for concern regarding the quantity and quality of sediment entering the reservoir. The U.S. 

Geological Survey collected two cores of bottom sediment to 

assess sediment accumulation and quality in Shawnee Mission 

Lake. Results from this study indicate that sediment accumulation has remained relatively constant from 1970–2006 at the 

downstream portion of the reservoir. Runoff from urban portions of the watershed are likely responsible for larger concentrations of selected trace elements in more recently deposited 

reservoir sediment. Information provided in this report can be 

used by Johnson County officials to help determine the current 

and future recreational capacity of the lake.

Introduction

In 1954, 1,248 acres of land were purchased by the Shawnee Mission Park District in north-central Johnson County, 

Kansas, for the development of a “big outdoor community 

playground” named Shawnee Mission Park (Barnes, 1956) 

(fig. 1). The centerpiece of the park is Shawnee Mission 

Lake, a 150-acre reservoir completed in 1962. The lake is 

one of the largest reservoirs in Johnson County, supporting 

swimming, boating, and fishing for area residents. Artificial 

impoundments such as Shawnee Mission Lake retain water 

and suspended sediment contributed by the surrounding watershed. Sediment accumulation in surface-water impoundments 

decreases water-storage capacity and can degrade the recreational and aesthetic value of the lake (Morris and Fan, 1997). 

Watersheds with little or no land disturbance typically 

yield the least amount of suspended sediment. Construction activities associated with urban development have been 

shown to increase stream-sediment loads by 100 times when 

compared to reference conditions (Wolman, 1967). After 

development, impervious surfaces, such as roads, driveways, 

and rooftops, route rainwater directly into streams, increasing stream velocities and the erosion of sediment from stream 

channels (Leopold and others, 2005). Nutrients, trace elements, and radionuclides adsorbed to sediment can act to 

degrade water quality in streams and lakes. Analysis of these 

chemical constituents in lake-bottom sediment can provide 

a history of sediment loading and quality in the watershed, 

which then can be related to changes in land use.

Prior to residential construction, the 1,860-acre Shawnee 

Mission Lake watershed was characterized by undisturbed, 

timbered rolling hills. Because of concerns regarding recent 

(1990–2006) urban development in the Shawnee Mission Lake 

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

with the Johnson County Stormwater Management Program, 

undertook a study of sediment deposition and quality in Shawnee Mission Lake. 

Purpose and Scope

This report describes bottom-sediment accumulation 

and quality in Shawnee Mission Lake. The U.S. Geological 

Survey collected two cores of bottom sediment in 2006 from 

Shawnee Mission Lake to estimate the amount of sediment 

deposition from 1962–2006 and to characterize the quality of 

sediment using historical reconstruction techniques (Juracek, 

2004; Van Metre and others, 2004). Results of nutrient, trace 

element, and radionuclide analysis of sediment cores collected 

in 2006 are described. These results support Federal, State, 

and local watershed efforts to improve water quality and to 

identify processes leading to increased transport of fluvial 

sediment. Information provided in this study can be used by 

Johnson County officials to help determine the current and 

future recreational capacity of Shawnee Mission Lake.

Acknowledgments

The authors are grateful to the Johnson County Museum 

for access to historical newspapers and aerial photography. 

The authors also thank Shannon Porter of the Johnson

County Automated Information Mapping System for 

Bottom-Sediment Accumulation and Quality in Shawnee 

Mission Lake, Johnson County, Kansas, 2006

By Casey J. Lee, Kyle E. Juracek, and Christopher C. Fuller
assistance in obtaining and working with geographic 

information system data. 

Methods

Sample Collection and Laboratory Methods

Two cores of bottom sediment from Shawnee Mission 

Lake (fig. 1) were collected in May (core 1) and November of 

2006 (core 2) using a gravity corer (fig. 2). Sediment cores 

were collected near the dam (fig. 1) because sediment accumulation there is typically the most homogenous and least prone 

to disturbance (Van Metre and others, 2004). Water depth 

at the coring sites was approximately 40 ft; the gravity corer 

was dropped into the sediment from a height of approximately 

10 ft above the lake bottom. Although several cores were 

collected in May and November 2006, recovering a range of 

10 to 21 in. of sediment, the two cores that were selected for 

analysis penetrated to original, pre-impoundment soils, which 

were distinguished from entrained sediment by the presence 

of rocks and root hairs. The use of a gravity corer can result 

in collection of a sediment profile shorter than the amount of 

actual sediment deposition. This “core shortening” results 

from the friction of the sediment against the inner wall of the 

sample tube and may not be uniform throughout the core. 

Studies in Kansas reservoirs have indicated core recoveries 

in the range of 50 to 75 percent of deposited sediments 

(Juracek, 2004).

Core 1 penetrated impoundment soils to a depth of 

20.5 inches and was sampled every 2 inches. Core 2 

Figure 1. Urban development in 

and near the Shawnee Mission 

Lake watershed, Johnson County, 

Kansas, 2006.

2 Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006

Park boundary

Park boundary Park boundary

Dam

Approximate 

boundary of 

Shawnee

Mission Lake

watershed

Approximate 

boundary of 

Shawnee

Mission Lake

watershed

87th Street Parkway Renner Rd Renner Rd

87th Street Parkway Renner Rd Renner Rd

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)

Development information from Johnson County

Automated Mapping System (written commun., 2006)

1901–55

1956–80

1981–90

Date of urban development

Sediment coring site and date 

 core was collected

EXPLANATION

1991–95

1996–2000

2001–05

Shawnee

Mission

Lake

May and

November

2006

Johnson

County

Location of 

study area

Index map

KANSAS

May and

November

2006

0 1,000 2,000 3,000 4,000 FEET

0 0 25 500 750 1,000 METERS

94°48' 47' 94°46'

38°59'

38°58'

Olathe

Johnson County

Kansas River

Gardner City Lake

Lake Olathe
penetrated impoundment sediment to a depth of 13 inches, and 

was subsampled every 1 inch. Core 1 was used for analysis 

of 4 radionuclides, nitrogen, phosphorus, and 27 trace elements; core 2 was analyzed for bulk density and radionuclides. 

Bulk-density analysis was performed using methods described 

in Guy (1969). Radionuclides were analyzed at the USGS 

laboratory in Menlo Park, California, using a high-resolution 

gamma spectrometer with an intrinsic germanium detector (Robbins and Edgington, 1986; Fuller and others, 1999). 

Nutrient and trace element analysis of lake sediment was 

performed by the USGS Sediment Trace Element Partitioning 

Laboratory in Atlanta, Georgia. Sediment was sieved to less 

than 63 μm (to compensate for potential grain-size differences) 

and analyzed for nutrients and trace elements using methods 

described in Horowitz and others (2001). 

Quality Control

One duplicate sample was analyzed for nutrient and trace 

element data. Relative percentage differences between original and duplicate analyses were generally within 10 percent, 

with the exception of cadmium (40 percent), selenium (31 percent), and tin (13 percent). Concentrations of these analytes 

were near laboratory reporting levels, thus small differences in 

concentration resulted in large percentage differences between 

original and duplicate analyses. Uncertainty estimates for 

radionuclide analyses are based on activity level and instrument calibration error. These estimates ranged from 0.01 to 

0.07 picocuries/gram for cesium-137 and from 0.12 to 0.47 for 

“excess” lead-210.

Age and Accumulation Rates of LakeBottom Sediment

Environmental activities of the radionuclides natural 

beryllium-7 (7Be), anthropogenic cesium-137 (137Cs), and lead210 (210Pb), were measured in the sediment cores to date the 

ages of lake-bottom sediment (tables 1 and 2). These radionuclides were found entrained on bottom sediment through atmospheric fallout to the lake surface and surrounding watershed, 

Figure 2. Photograph showing pontoon boat mounted with gravity corer used to collect bottom sediment cores from Shawnee Mission Lake May 

and November 2006.

Age and Accumulation Rates of Lake-Bottom Sediment 3
and subsequent deposition to the lake bottom. After deposition, radionuclides decayed at varying rates depending on their 

respective half-lives (53.3 days for 7Be, 30.3 years for 137Cs, 

and 22.3 years for 210Pb) (Holmes, 1998). 7

Be is produced in the upper atmosphere by cosmic 

ray interaction with nitrogen. Because of its short half-life, 

detection in lake-bottom sediment indicates recent sediment 

accumulation and mixing of sediment. 137Cs was artificially 

produced as a byproduct of nuclear fission; global release 

to the environment occurred from above-ground nuclear 

weapons testing. Measurable fallout of 137Cs began in 1952. 

Maximum fallout deposition occurred in 1963–64; then 

decreased steadily due to the nuclear test ban treaty of 1963 

(Ritchie and McHenry, 1990). 210Pb is a naturally occurring 

isotope in the uranium-238 decay series. When compared to 

the activity of its long-lived parent, 226Ra, levels of “excess” 210Pb in lake-bottom sediment can be used to age date coresediment profiles.

The constant flux:constant sedimentation method 

(Appleby and Oldfield, 1992) was used to age date sediment 

intervals from “excess” 210Pb profiles. The 137Cs profile then 

was used as a test of the “excess” 210Pb-derived sediment 

accumulation rate and as an indicator of sediment mixing 

or reworking (Fuller and others, 1999). Precipitation data 

recorded at Olathe, Kansas, generally indicate even distribution of precipitation amount and intensity since 1962 (fig. 3). 7

Be was not detected in either sediment core because 

sediment with detectable activity was diluted by previously 

deposited sediment in which 7Be activity had decayed to less 

than laboratory reporting levels (tables 1 and 2). 137Cs activity had well-defined peak values in both cores followed by 

an exponential decrease in activity (fig. 4), indicating that 

sediment profiles in the cores were undisturbed by mixing 

(Van Metre and others, 1997). Excess 210Pb data had a twoslope exponential decrease in core 1 (1 in/yr from 1964–1970; 

0.19 in/yr from 1970–2006) and a more uniform exponential 

decrease in core 2 (fig. 4). Anomalies in constant decay rate 

in the 7- and 9-in. depth intervals (fig. 4B) of core 2 may have 

been caused by shoreline erosion, road construction at the 

inception of the park, or by soils disturbed during construction 

of the reservoir. Data below a depth of about 15 in. in core 1, 

and below 11 in. in core 2, had little excess 210Pb activity and 

represent original, pre-impoundment soils (tables 1 and 2). 

Sediment accumulation rates were estimated at 

0.31 in/yr in core 1 and 0.26 in/yr in core 2 for 1964–2006. 

Mass accumulation rates for core 2 of 0.07 lbs per square ft 

were calculated with excess 210Pb and bulk density using the 

CF:CS method (Appleby and Oldfield, 1992). These rates 

4 Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006

Figure 3. Annual precipitation and number of days in which greater than 1 inch of rainfall, Olathe, Kansas, 1960–2006 (Data from National Oceanic 

and Atmospheric Administration, 2007).

Number of days with greater than 1 inch of rain

0

10

20

30

40

50

60

70

Annual precipitation, (in) 

0

5

10

15

20

25

Number of days with greater than 1 inch of precipitation recorded

Annual precipitation

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006
Table 1. Activities and concentrations of radionuclides, nutrients, and trace elements in core 1, Shawnee Mission Lake bottom sediment,

May 2006.

[<LRL, less than laboratory reporting level; mg/kg, milligrams per kilogram; dpm/g, disintegrations per minute per gram; n, number of samples collected; in, 

inches; --, not determined]

Constituent Laboratory reporting 

level

Probable effect 

concentration1

Concentration at specified depth intervals (inches) 

0–2 2–4 4–6 6–8 8–10 10–12

Radionuclides

7

Beryllium 0.04 dpm/g -- <LRL <LRL <LRL <LRL <LRL <LRL

137Cesium 0.07 dpm/g -- 0.29 0.42 0.55 0.51 1.1 1.7

“Excess” 210Lead 0.07 dpm/g -- 2.4 2.2 1.8 1.4 1.5 1.4

Nutrients 

Nitrogen 100 mg/kg -- 3,600 3,400 6,900 3,000 3,800 3,600

Phosphorus 100 mg/kg -- 1,100 1,000 1,000 1,000 1,300 1,300

Trace elements

Aluminum 1 mg/kg -- 9.0 8.8 8.5 8.6 8.2 8.0

Antimony .1 mg/kg -- 1.4 1.4 1.3 1.3 1.3 1.4

Arsenic .1 mg/kg 33 20 24 21 19 21 20

Barium 1 mg/kg -- 760 750 750 760 700 750

Berlyllium .1 mg/kg -- 2.6 2.6 2.4 2.4 2.3 2.3

Cadmium .1 mg/kg 5.0 .6 .7 .6 .5 .6 .8

Chromium 1 mg/kg 111 110 99 90 89 86 84

Cobalt 1 mg/kg -- 15 16 15 13 12 15

Copper 1 mg/kg 149 32 32 31 31 30 30

Iron 1,000 mg/kg -- 46,000 47,000 46,000 43,000 42,000 42,000

Lead 1 mg/kg 128 33 31 29 33 38 35

Lithium 1 mg/kg -- 59 58 53 52 50 50

Manganese 10 mg/kg -- 1,200 1,200 1,500 1,100 1,200 1,200

Molybdenum 1 mg/kg -- 1.6 1.8 1.3 1.4 1.5 1.7

Nickel 1 mg/kg 49 49 47 43 41 39 41

Selenium .1 mg/kg -- 1.2 1.4 1.1 1.3 1.3 1.3

Silver .5 mg/kg -- <LRL <LRL <LRL <LRL <LRL <LRL

Strontium 1 mg/kg -- 140 140 140 120 140 160

Sulfur 1,000 mg/kg -- 4,000 5,600 5,600 3,300 4,600 5,300

Thallium 50 mg/kg -- <LRL <LRL <LRL <LRL <LRL <LRL

Tin .1 mg/kg -- 2.3 3.8 3.8 3.2 2.6 4.2

Titanium 50 mg/kg -- 4,200 4,200 4,000 4,000 3,800 4,000

Total carbon 1,000 mg/kg -- 32,000 31,000 68,000 30,000 40,000 38,000

Total organic carbon 1,000 mg/kg -- 28,000 29,000 28,000 26,000 31,000 29,000

Uranium .05 mg/kg -- <LRL <LRL <LRL <LRL <LRL <LRL

Vanadium 1 mg/kg -- 140 130 130 130 120 120

Zinc 1 mg/kg 459 170 170 150 150 140 130

Age and Accumulation Rates of Lake-Bottom Sediment 5
Table 1. Activities and concentrations of radionuclides, nutrients, and trace elements in core 1, Shawnee Mission Lake bottom 

sediment, May 2006.—Continued

[<LRL, less than laboratory reporting level; dpm/g, disintegrations per minute per gram; mg/kg, milligrams per kilogram; n, number of samples 

collected; in, inches; --, not determined]

Constituent Laboratory reporting 

level

Probable 

effect concentration1

Concentration at specified depth intervals (inches)

12–14 14–16 16–18 18–20.5

Radionuclides

7

Beryllium 0.04 dpm/g -- <LRL <LRL <LRL <LRL

137Cesium 0.07 dpm/g -- 5.5 0.41 0.37 0.37

“Excess” 210Lead 0.07 dpm/g -- 1.3 .34 -.13 .20

Nutrients 

Nitrogen 100 mg/kg -- 3,000 1,200 870 1,000

Phosphorus 100 mg/kg -- 1,200 810 630 530

Trace elements

Aluminum 1 mg/kg -- 9.1 8.4 7.2 6.1

Antimony .1 mg/kg -- 1.4 1.2 1.0 .9

Arsenic .1 mg/kg 33 18 9.7 9.1 7.7

Barium 1 mg/kg -- 790 760 740 720

Berlyllium .1 mg/kg -- 2.7 2.5 2.1 1.7

Cadmium .1 mg/kg 5.0 .8 .6 .3 .2

Chromium 1 mg/kg 111 95 87 72 59

Cobalt 1 mg/kg -- 15 13 11 9

Copper 1 mg/kg 149 38 27 23 18

Iron 1,000 mg/kg -- 46,000 39,000 33,000 26,000

Lead 1 mg/kg 128 34 24 22 18

Lithium 1 mg/kg -- 55 46 39 31

Manganese 10 mg/kg -- 1,200 770 660 550

Molybdenum 1 mg/kg -- 1.5 <LRL 0.8 <LRL

Nickel 1 mg/kg 49 45 38 31 24

Selenium .1 mg/kg -- 1.2 .6 .6 .5

Silver .5 mg/kg -- <LRL <LRL .8 <LRL

Strontium 1 mg/kg -- 120 120 110 120

Sulfur 1,000 mg/kg -- 2,900 440 250 210

Thallium 50 mg/kg -- <LRL <LRL <LRL <LRL

Tin .1 mg/kg -- 2.8 2.5 1.8 2.8

Titanium 50 mg/kg -- 4,300 4,300 4,200 4,100

Total carbon 1,000 mg/kg -- 30,000 11,000 8,000 8,000

Total organic carbon 1,000 mg/kg -- 26,000 10,000 8,000 7,000

Uranium .05 mg/kg -- <LRL <LRL <LRL <LRL

Vanadium 1 mg/kg -- 140 120 100 84

Zinc 1 mg/kg 459 150 120 93 72

1

From MacDonald and others (2000).

6 Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006
Table 2. Activities of radionuclides in core 2, Shawnee Mission Lake bottom sediment, Johnson County, Kansas, November 2006. 

[lb/ft3, pound per cubic foot; <LRL, less than laboratory reporting level; dpm/g, disintegrations per minute per gram; in, inches]

Constituent

Unit of 

measurement

Bulk density or concentrations at specified depth interval (inches)

0–1 1–2 2–3 3–4 4–5 5–6 6–7 7–8 8–9 9–10 10–11 11–12 12–13

Bulk density (lb/ft3)

Bulk Density lb/ft3 8.52 18.5 15.6 14.3 17.1 19.7 15.8 17.6 16.2 18.3 24.4 48.9 47.5

Radionuclides

7

Beryllium 0.04 dpm/g <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL <LRL

137Cesium 0.07 dpm/g .25 .26 .41 .50 .46 .69 1.1 1.1 1.3 1.5 3.2 .94 .29

“Excess” 210lead0.07 dpm/g 8.1 6.9 6.8 5.6 5.0 4.7 4.3 2.1 3.2 3.7 2.4 .32 .74

Age and Accumulation Rates of Lake-Bottom Sediment 7

0

2

4

6

8

10

12

14

16

18

20

Estimated year of deposition using excess lead-210

2001

1991

1980

1970

1968

1966

1964

2005

1995

1985

1975

1965

1955

Pre-impoundment soils 

Sediment accumulation

Pre-impoundment soils 

Sediment accumulation

(A) Core 1

(B) Core 2

Estimated sediment accumulation

rate 1970-2006 = 0.19 inch per year

Total estimated sediment accumulation

rate 1964-2006 = 0.31 inch per year

Total estimated sediment accumulation

rate 1964-2006 = 0.26 inch per year

(Top of core)

0

2

4

6

8

10

12

14

Core depth, inches

(Top of core)

(Bottom of core) 

(Bottom of core) 

Estimated sediment accumulation

rate 1964-1970 = 1.0 inch per year

1963-1964 137

Cs peak

1963-1964 137

Cs peak

0.1 1.0 10.0

Activity picocuries per gram

Cesium-137

Cesium-137

Excess lead-210

Excess lead-210

Figure 4. Cesium-137 and excess lead-210 activity in relation to core depth and estimated year of deposition in Shawnee 

Mission Lake bottom sediment.
were used to assign average dates of deposition for each vertical core depth interval. The resulting dates agree well with the 

known 1963-64 peak in 137Cs fallout delivery (fig. 4). 

Core 1 indicated accelerated deposition from 1964–70 

(approximately 1 in/year), with substantially less deposition from 1970–2006 (approximately 0.19 in/yr; fig. 4A). 

Increased erosion rates during early stages of the park may be 

related to soil disturbance during construction of the park and 

lake and (or) potential effects from core shortening. However, sediment accumulation rates calculated from the core 2 

generally were constant during the past 45 years (0.26 in/yr; 

fig. 4B). Deposition rates calculated from sediment-coring 

methods did not indicate increased sediment loading associated with recent residential construction in the watershed. 

Erosion-control measures such as stormwater detention basins 

or protection of riparian areas enacted during residential 

construction may have minimized transport of sediment into 

area streams. Additionally, sediment loading from residential 

construction may have been deposited in the upstream end of 

the lake, remained in suspension long enough to pass through 

the impoundment outflow, or was underrepresented due to 

core shortening during sample collection.

 Differences in deposition rates between the two cores 

collected for this study are likely related to differences 

in the length of sediment penetrated in each core sample. 

These differences are caused by localized variation in either 

sediment deposition or in the amount of “core shortening” 

between samples. 

Nutrient and Trace Element 

Concentrations

Nutrient and trace element concentrations in lakebottom sediment were used to characterize current (2006) 

and historical sediment quality in Shawnee Mission Lake and 

the surrounding watershed (table 1). Selected nutrient and 

trace element data were compared to data collected from two 

other Johnson County lakes of similar size and age—Gardner 

City Lake (impounded in 1940; Juracek, 2004), and Lake 

Olathe (impounded in 1956; Mau, 2000) (fig. 4). Constituents 

compared between Johnson County lakes have either previously been used to age-date sediment or have been observed 

to increase in urbanized watersheds were chosen for analysis 

(Van Metre and others 2004; Mahler and others, 2006). Trace 

element concentrations were compared to probable effect 

concentrations (PECs), which are concentrations above which 

a particular constituent shows a statistical relation to adverse 

biological effects (MacDonald and others, 2000). These 

guidelines are used exclusively for comparative purposes and 

do not imply direct cause-effect relations between sediment 

concentrations and adverse biological effects. 

Nutrient and trace element concentrations in Shawnee 

Mission Lake bottom sediment generally were within the 

range of the other area lakes and were less than respective 

PEC values. Shawnee Mission Lake also had slightly larger 

particulate total nitrogen concentrations than the other two 

area lakes, including a large spike in values (6,900 mg/kg) in 

the core interval between 4 and 6 in,; the cause of this spike 

is unknown as there was no evidence of pronounced changes 

in land use during this period. Nickel was the only constituent with values equal to (or larger than) the PEC (49 mg/kg). 

Although concentrations of nutrients and trace elements in 

Shawnee Mission Lake sediment generally were within the 

range of the other two area lakes, selected trace elements 

had increasing concentrations in more recent sediment from 

Shawnee Mission Lake (fig. 5). Among the three lakes, 

increases in chromium, lead, nickel, and zinc in more recent 

(1990–present) deposition were exclusive to Shawnee Mission 

Lake and likely are indicative of localized urbanization (table 

1, fig. 5). Atmospheric deposition (for chromium, lead, nickel, 

and zinc), roof shingles (particularly for lead and zinc) and 

tire wear (zinc) have been shown to be important sources of 

contamination in urban environments (Van Metre and Mahler, 

2003; Mahler and others, 2006). Major human-related sources 

of nickel include industrial and indirect emission of nickel as 

an impurity in coal and oil combustion (U.S. Environmental 

Protection Agency, 1984).

Summary

The U.S. Geological Survey, in cooperation with the 

Johnson County Stormwater Management Program, undertook 

a study to characterize sediment accumulation and quality in 

Shawnee Mission Lake. Two bottom-sediment cores were collected from Shawnee Mission Lake to characterize sediment 

accumulation and quality relative to ongoing urbanization 

in the upstream watershed. Both cores had similar average sediment accumulation rates (core 1, 0.31 in/yr; core 2, 

0.26 in/yr), and neither core indicated increased sediment 

deposition associated with recent urban development in the 

watershed. However sediment accumulation estimates could 

be affected by uneven distribution of sediment deposition 

across the reservoir or by shortening of the sediment core 

during sampling. Recent urban development (1990 to present) 

in the Shawnee Mission Lake watershed is likely associated 

with increasing concentrations of chromium, lead, nickel, and 

zinc in recently deposited bottom sediment. Information on 

the rates and quality of sediment accumulation can be used 

by Johnson County officials to help determine the current and 

future recreational capacity of the lake. 

8 Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006
Summary 

9

2001

199119801970196819661964

Estimated date of sediment interval for Shawnee Mission Lake

(B) Lead

20 25 30 35 40 45 50 55

Concentrations, in milligrams per kilogram

Probable effectconcentrationPEC = 49 mg/kg 

Probable effectconcentrationPEC = 459 mg/kg 

(C) Nickel

15 20 25 30 35 40 45 50 55

Concentrations, in milligrams per kilogram

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000

Concentrations, in milligrams per kilogram

Most recent n depositio

Oldest

deposition 

(A) Total nitrogen

60 80 100 120 140 160 180 200

Concentrations, in milligrams per kilogram

2001199119801970196819661964

Approximate

peak in lead

emissions (from

leaded gasoline)

Lead sources

associated

with recent

urbanization

(D) Zinc

Core interval

Most recent n depositio

Oldest

deposition 

EXPLANATION

Probable effect concentrationPEC = 128 mg/kg 

Shawnee Mission Lake

pre-impoundment soils

Shawnee Mission Lake

sediment accumulation soils

Shawnee Mission Lake (impounded 1962)Gardner City Lake (impounded 1940)Lake Olathe (impounded 1956)

Probable effects concentrations (PECs) from MacDonald and others (2000). Data for Gardner City Lake from Juracek (2004) and for Lake Olathe from Mau (2000).

Figure 5. Selected nutrient and trace element profiles in bottom-sediment cores from three Johnson County lakes. Probable effects concentrations (PECs) from MacDonald and others (2000). Data for Gardner City Lake from Juracek (2004) and for Lake Olathe from Mau (2000).
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earth, marine, and environmental sciences (2d ed.): Oxford, 

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of selected chemical constituents in bottom sediment of 

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in metals in urban and reference lake sediments across the 

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northeast Kansas, 2000: U.S. Geological Survey WaterResources Investigations Report 02–4073, 71 p. 

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Climatic Data Center: Information available on the web, 

accessed August 13, 2007 at http://www.ncdc.noaa.gov/oa/

climate/stationlocator.html

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sediment accumulation rates and patterns: A review: Journal 

of Environmental Quality, v. 19, p. 215–233.

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recent sedimentation rates in Lake Michigan using 210Pb and 137Cs: Geochimica et Cosmochimica Acta v. 39, p. 285–304.

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estimating air emissions from sources of nickel: U.S. Environmental Protection Agency Report 450/4-84-007f, various 

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particles washed from rooftops to contaminant loading to 

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and Mahler, B.J., 2004, Collection, analysis, and age dating of sediment cores from 56 U.S. lakes and reservoirs 

sampled by the U.S. Geological Survey, 1992–2001: U.S. 

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10 Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006
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Lee and others—Bottom-Sediment Accumulation and Quality in Shawnee Mission Lake, Johnson County, Kansas, 2006—Scientific Investigations Report 2007–5274

Park boundary

Park boundary

Dam

Approximate 

boundary of 

Shawnee

Mission Lake

watershed

§ ̈¦435

87th Street Parkway Renner Rd

§ ̈¦435

Renner Rd

87th Street Parkway Renner Rd

Shawnee

Mission 

Lake

May and

November 

2006