Prepared in cooperation with the 

BUREAU OF RECLAMATION

Deposition of Selenium and Other 

Constituents in Reservoir Bottom 

Sediment of the Solomon River 

Basin, North-Central Kansas

Water-Resources Investigations Report 99-4230

O'O

U.S. Department of the Interior 

U.S. Geological Survey
B.

E.

D.

A. Dam overlooking Kirwin Reservoir

B. Waconda Lake

C. Webster Reservoir

D. Kirwin National Wildlife Refuge

E. Gravity corer mounted on pontoon boat

(photographs A-D taken by author; 

photograph E taken by David P. Mau, 

U.S. Geological Survey, Lawrence, Kansas)
U.S. Department of the Interior 

U.S. Geological Survey

Prepared in cooperation with the 

BUREAU OF RECLAMATION

Deposition of Selenium and Other 

Constituents in Reservoir Bottom 

Sediment of the Solomon River 

Basin, North-Central Kansas

By VICTORIA G. CHRISTENSEN 

Water-Resources Investigations Report 99-4230

Lawrence, Kansas 

1999
U.S. Department of the Interior

Bruce Babbitt, Secretary

U.S. Geological Survey

Charles G. Groat, Director

The use of brand, firm, or trade names in this report is for identification purposes only and does not constitute endorsement by the 

U.S. Geological Survey.

For additional information write to: Copies of this report can be purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Information Services 

4821 Quail Crest Place Building 810 

Lawrence, KS 66049-3839 Box 25286, Federal Center

Denver, CO 80225-0286
CONTENTS

Abstract...............................................................................................................^ 1

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

Purpose and Objectives.......................................................................................................................................................... 3

Basin Description .................................................................................................................................................................. 3

Methods........................................................................................................^ 5

Sediment-Core Collection, Processing, and Analysis ................................................................................................. 5

Quality Control ............................................................... 10

Trend Analysis............................................................................................................................................................. 11

Results of Reservoir Bottom-Sediment Analysis .................................................................................................................. 12

Sediment-Core Lithology and Grain Size ................................................................................................................... 12

Age Dating and Depositional Patterns of Bottom Sediment ...................................................................................... 13

Concentrations and Trends in Selected Chemical Constituents ................................................................................. 16

Selenium.......................................................................^ 17

Arsenic..................................................................................................^^ 22

Strontium ........................................................................................................................................................^ 22

Nutrients and Total Organic Carbon.................................................................................................................. 26

Bottom-Sediment Volume and Mass in Webster Reservoir......................................................................................... 26

Selenium, Arsenic, and Strontium Loads in Webster Reservoir.................................................................................. 27

Comparison of Depositional Trends to Irrigation and Constituent Loads............................................................................. 27

Summary.........................................................^ 30

References .................................................................................................:........................................................................... 32

Supplemental Information ....................................................................................................................... 35

FIGURES

1. Maps showing location and near-surface geology of the Solomon River Basin, north-central Kansas.................. 2

2. Maps showing approximate location of sediment-coring sites in Kirwin Reservoir, Webster Reservoir, and

WacondaLake......................................................................................................................................................... 6

3. Photographs showing gravity corer mounted on pontoon boat and core preparation............................................. 9

4-11. Graphs showing:

4. Depth-normalized cesium-137 profiles in selected bottom-sediment cores collected in May 1998 from

Kirwin Reservoir, Webster Reservoir, and Waconda Lake................................................................................ 14

5. Historical inflows to Kirwin Reservoir, Webster Reservoir, and Waconda Lake.............................................. 15

6. Depth-normalized selenium concentration profiles in selected bottom-sediment cores collected in

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake...................................................... 23

7. Depth-normalized arsenic concentration profiles in selected bottom-sediment cores collected in

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake...................................................... 24

8. Depth-normalized strontium concentration profiles in selected bottom-sediment cores collected in

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake...................................................... 25

9. Irrigated acres in Kirwin and Webster Irrigation Districts, 1957-97 ................................................................ 28

10. Background and post-background selenium, arsenic, and strontium concentrations in bottom sediment 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake and estimated background and postbackground selenium, arsensic, and strontium annual loads in Webster Reservoir.......................................... 29

11. Background and post-background mean annual streamflow into Kirwin Reservoir, Webster Reservoir,

and WacondaLake............................................................................................................................................. 30

Contents
TABLES

1. Distribution of irrigated acres in the Solomon River Basin, 1995.......................................................................... 5

2. Location of bottom-sediment coring sites in the Solomon River Basin, May 1998............................................... 8

3. Mean relative percentage differences for total recoverable metals, nutrients, and total organic carbon 

concentrations in sequential replicate samples from bottom-sediment coring sites WAC 1 and WAC 2 in 

Waconda Lake, May 1998 ...................................................................................................................................... 10

4. Mean relative percentage differences for total recoverable metals, nutrients, and total organic carbon

concentrations in bottom-sediment samples from Kirwin and Webster Reservoirs, May 1998............................. 11

5. Sediment-recovery percentages in cores collected from Kirwin Reservoir, Webster Reservoir, and Waconda

Lake, May 1998..................................................................................................................^ 12

6. Mean percentage of silt and clay, percentage of sand, bulk density, and percentage of moisture in bottomsediment samples from coring sites in Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998..... 13

7. Statistical summary of selected constituent concentrations in bottom-sediment samples from Kirwin

Reservoir, Webster Reservoir, and Waconda Lake, May 1998, and comparison to sediment-quality guidelines.. 17

8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected from

Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 .................................................................. 18

9. Core length, estimated sediment thickness, and recovery percentage for multiple cores from sediment coring

sites in Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 ...................................................... 37

10. Results of analyses of selected physical properties for bottom-sediment cores collected in May 1998 from

Kirwin Reservoir, Webster Reservoir, and Waconda Lake..................................................................................... 38

11. Results of analyses of sediment-quality constituents in bottom-sediment cores collected from Kirwin

Reservoir, Webster Reservoir, and Waconda Lake, May 1998............................................................................... 41

CONVERSION FACTORS AND ABBREVIATIONS

Multiply By To obtain

acre 4,047 square meter

acre-feet (acre-ft) 1,233 cubic meter

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

foot (ft) 0.3048 meter

inch (in.) 2.54 centimeter

mile (mi) 1.609 kilometer

pound (Ib) 0.4536 kilogram

pound per cubic foot (lb/ft3 ) 16.02 kilogram per cubic meter

pound per year (Ib/yr) 0.4536 kilogram per year

square mile (mi2) 2.590 square kilometer

Temperatures in this report can be converted to degrees Celsius (°C) or degrees Fahrenheit (°F) by the 

equations:

°C = 5/9 (°F-32) 

°F = 9/5 (°C) + 32.

Water year: Water year as used in this report refers to the 12-month period beginning October 1 and 

ending September 30. The water year is designated by the calendar year in which it ends; for example, 

the 1998 water year begins October 1, 1997, and ends September 30, 1998.

IV Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Deposition of Selenium and Other Constituents in 

Reservoir Bottom Sediment of the Solomon River Basin, 

North-Central Kansas

By Victoria G. Christensen

Abstract

The Solomon River drains approximately 

6,840 square miles of mainly agricultural land in 

north-central Kansas. The Bureau of Reclamation, U.S. Department of the Interior, has begun a 

Resource Management Assessment (RMA) of the 

Solomon River Basin to provide the necessary 

data for National Environmental Policy Act 

(NEPA) compliance before renewal of long-term 

water-service contracts with irrigation districts in 

the basin. In May 1998, the U.S. Geological Survey (USGS) collected bottom-sediment cores 

from Kirwin and Webster Reservoirs, which are 

not affected by Bureau irrigation, and Waconda 

Lake, which receives water from both Bureau and 

non-Bureau irrigated lands. The cores were analyzed for selected physical properties, total recoverable metals, nutrients, cesium-137, and total 

organic carbon.

Spearman's rho correlations and Kendall's tau 

trend tests were done for sediment concentrations 

in cores from each reservoir. Selenium, arsenic, 

and strontium were the only constituents that 

showed an increasing trend in concentrations for 

core samples from more than one reservoir. Concentrations and trends for these three constituents 

were compared to information on historical irrigation to determine any causal effect. Increases in 

selenium, arsenic, and strontium concentrations 

can not be completely explained by Bureau irrigation. However, mean selenium, arsenic, and strontium concentrations in sediment from all three 

reservoirs may be related to total irrigated acres

(Bureau and non-Bureau irrigation) in the basin. 

Selenium, arsenic, and strontium loads were calculated for Webster Reservoir to determine if 

annual loads deposited in the reservoir were 

increasing along with constituent concentrations. 

Background selenium, arsenic, and strontium 

loads in Webster Reservoir are significantly larger 

than post-background loads.

INTRODUCTION

The Solomon River Basin extends across parts of 

17 counties in north-central Kansas (fig. 1) and 

includes the Solomon River and its major tributaries 

the North Fork Solomon River and the South Fork 

Solomon River. The Solomon River drains about 

6,840 mi of mainly agricultural land. The Solomon 

River Basin is underlain by strata of marine origin. 

Irrigation return flow in areas underlain by these strata 

may contain concentrations of selenium that, when 

introduced into a lake, reservoir, or wetland area, 

could bioaccumulate to levels toxic to aquatic organisms, predatory species, or potentially could affect 

human health through consumption of contaminated 

organisms (Ramirez and Armstrong, 1992; Roy and 

O'Brien, 1992).

Selenium often is redistributed by irrigated agriculture (Sharma and Singh, 1983), and there is a concern about selenium concentrations in the Solomon 

River Basin where irrigation by the Bureau of Reclamation (Bureau), U.S. Department of the Interior, 

began in the late 1950's. Irrigation return flow also 

may contain large concentrations of dissolved constituents that may affect the quality of receiving stream 

water (Mueller and others, 1991; Engberg, 1993).

Introduction
N3

o(A OU)2.(D

3 oa. Oooc(DU

m </> n>

o-r'

0) OW(D Q.(DO O5

(D 

CD

o> 3'

o

3.6

33

fi) 3fi) V)

Jefferson

Harlan Franklin Thayer Dundy Hitchcock

Sheridan /; Graham 0687300o I Rooks 06871500 Qsbome 06874000

I Boundary 

Solomon River 

Basin

Base from U.S. Geological Survey digital data, 1:100,000,1995

Universal Transverse Mercator projection

Zone 14

Converted to Lambert Conformal Conic projection.Standard parallels 33° and 45°, central meridian -98°18'45"

pn<.., *K Geology modified from Kansas Geological Survey, digital data, 1992, tilswortn scale 1:500,000, and Ross, 1991

Index map

Quaternary System

] Alluvium, dune sand, and loess

Tertiary System

I Ogallala Formation

EXPLANATION

Cretaceous System

_I Niobrara Formation| Carlile Shale, Greenhorn Limestone, 

and Graneros Shale

f Dakota Formation, Kiowa Shale, 

and Cheyenne Sandstone

20 30 40 MILES

10 20 30 40 KILOMETERS

Permian System

| Sumner Group

06874000A US. Geological Survey

streamflow-gaging station 

and number

KANSAS I

Figure 1. Location and near-surface geology of the Solomon River Basin, north-central Kansas.
Public Law 99-294, National Environmental Policy 

Act (NEPA) of 1986, requires that the Bureau investigate soil characteristics that may result in toxic or hazardous irrigation return flows. The Bureau, in 

response, has begun a Resource Management Assessment (RMA) of the Solomon River Basin to provide 

the necessary data for NEPA compliance before 

renewal of long-term water-service contracts with irrigation districts in the basin.

The study described in this report was begun in the 

spring of 1998 by the U.S. Geological Survey (USGS) 

in cooperation with the Bureau to determine if Bureauoperated irrigation (hereinafter referred to as Bureau 

irrigation) has increased selenium or other constituent 

concentrations in the basin. There are three reservoirs 

in the Solomon River Basin Kirwin Reservoir on the 

North Fork Solomon; Webster Reservoir on the South 

Fork Solomon; and Waconda Lake on the main stem 

of the Solomon River (fig. 1). Three Bureau waterresource developments are located within the 

basin the Kirwin Irrigation District, the Webster Irrigation District, and the Glen Elder Irrigation District 

(Bureau of Reclamation, 1984). The drainage areas 

upstream from Kirwin and Webster Reservoirs are not 

affected by Bureau irrigation, and therefore, bottom 

sediment from these reservoirs was used to determine 

background sediment concentrations of selected constituents and to evaluate the effects of other (nonBureau) irrigation activities. Waconda Lake receives 

water from both the Kirwin Irrigation District and the 

Webster Irrigation District, and therefore, the bottom 

sediment from Waconda Lake was used to assess 

trends in chemical constituents in sediment for the 

entire Solomon River Basin and to help distinguish the 

effect of Bureau irrigation in the basin. Sediment quality is of concern because it reflects the quality of the 

overlying water column.

PURPOSE AND OBJECTIVES

The primary purpose of this report is to document 

baseline conditions and trends in deposition of selenium and other constituents in three reservoirs of the 

Solomon River Basin. Other objectives of this report 

are: (1) to evaluate these trends in relation to Bureau 

irrigation in the basin, (2) to document the volume and 

mass of sediment accumulated in Webster Reservoir 

(for which bathymetric and sedimentation data were 

available) since dam closure, and (3) to estimate the

mass and annual load of selenium, arsenic, and strontium deposited in Webster Reservoir.

Baseline conditions and trends in bottom-sediment 

quality were documented through chemical analysis 

and age dating of bottom-sediment cores. Trends in 

constituent concentrations were determined using 

Spearman's rho correlation and Kendall's tau trend 

tests. The constituents (selenium, arsenic, and strontium) that have increasing trends in more than one reservoir are discussed in detail.

Additional samples collected from Webster Reservoir and Bureau sedimentation data were used to estimate the mass of sediment accumulated in Webster 

Reservoir since dam closure. These additional samples 

and data also were used to estimate the mass and 

annual load of selenium, arsenic, and strontium transported into Webster Reservoir for the purpose of comparing the annual loads to any trend in constituent 

concentration.

Results contained in this report may have transferability to other reservoir watersheds in Kansas and the 

Nation or to other areas with similar soils, geology, 

land use, and agricultural and cropping practices.

BASIN DESCRIPTION

The Solomon River Basin has a subhumid climate, 

with a mean annual temperature of about 53 °F and 

average annual precipitation of about 28 in. (National 

Oceanic and Atmospheric Administration, 1997). The 

drainage pattern of the Solomon River is dendritic 

(tree-like branching) and lacks symmetry, which suggests the lack of faults and folds and the presence of 

flat underlying rock units (Bureau of Reclamation, 

1984). The topography of the basin is generally flat 

with shallow valleys and low relief.

The soils in the valleys are slightly sloping, friable, and generally have high agricultural productivity. 

In the western and central parts of the basin, soils are 

generally friable and relatively impermeable, with 

some silt loam and loess. The more level soils in the 

western and central parts of the basin are used for 

grain cultivation and are moderately productive. The 

soils in the eastern part of the basin range from shallow sandy soils to thick clay soils and generally have 

low agricultural productivity (Bureau of Reclamation, 

1984).

Near-surface rocks in the Solomon River Basin are 

sedimentary and range in age from Permian to Quaternary (fig. 1). The near-surface geology has a general

Basin Description
east-west pattern, with the oldest rocks in the east and 

the youngest rocks in the west. The oldest near-surface 

rocks are the Permian-age Sumner Group (which 

includes the Wellington Formation and the Ninnescah 

Shale) at the far eastern end of the study area. Overlying the Sumner Group are marine strata of Cretaceous 

age that include the Cheyenne Sandstone, Kiowa 

Shale, Dakota Formation, Graneros Shale, Greenhorn 

Limestone, and Carlile Shale. These rocks are exposed 

at the land surface in parts of Ottawa County in the 

east to parts of Osborne County in the west (Moore 

and Landes, 1937). Overlying the Carlile Shale are the 

Niobrara Formation, which is exposed in much of the 

North Fork Solomon River Basin (Leonard, 1952), and 

the Pierre Shale, of which there is only one known outcrop in the basin (Moore and Landes, 1937; Ross, 

1991). At the western end of the basin, parts of the 

Ogallala Formation occur at the land surface.

In the Great Plains (a semiarid region that includes 

Kansas), the main source of selenium is Cretaceousage marine shale, specifically the Pierre Shale 

(McNeal and Balistrieri, 1989). The only known outcrop of Pierre Shale in the basin is upstream from

Webster Reservoir (fig. 1); however, other marine o

rocks do contain selenium. Selenate (SeO4 "), the 

most dominant form of selenium, is highly mobile and 

easily leached from soils by irrigation return flows. 

Reservoir-bottom sediment is an integrator of the 

water quality upstream from the reservoirs, and 

changes in land- and water-use practices through time 

are.recorded with the deposition of sediment in reservoirs (Van Metre and others, 1996, 1997).

The three Bureau reservoirs in the Solomon River 

Basin provide water for irrigation; municipal, industrial, and domestic use; flood control; recreation; and 

fish and wildlife habitat. Fishing, hunting, and waterrelated recreation play an increasingly important role 

in the economy of the basin (Bureau of Reclamation, 

written commun., 1996).

Kirwin Reservoir, completed in 1952, has a contributing drainage area of 1,367 mi2 , with a total storage capacity of 314,550 acre-ft of water allocated 

among flood control (215,115 acre-ft), conservation 

storage (89,650 acre-ft), and inactive and dead storage 

(9,785 acre-ft). During typical conditions, there are 

5,073 acres of water-surface area that are available for 

recreation. Also, there are 5,923 acres of land surrounding the reservoir that are available for recreational use. The Kirwin National Wildlife Refuge, 

operated on public lands by the U.S. Fish and Wildlife

Service, provides for the preservation of waterfowl, 

other animals, and plant life. Inflow to the reservoir 

may be affected by irrigation return flow from nonBureau-operated irrigation areas. The Bureau-operated 

Kirwin Irrigation District No. 1 is located downstream 

from the reservoir and provides surface-water outflow 

from the reservoir to irrigate as much as 11,490 acres 

of farmland (Bureau of Reclamation, 1996), generally 

within 5 mi of the North Fork Solomon River.

Webster Reservoir, completed in 1956, has a con-

^

tributing drainage area of 1,150 mi , with a total storage capacity of 260,740 acre-ft of water allocated 

among flood control (183,369 acre-ft), conservation 

storage (72,071 acre-ft), and inactive and dead storage 

(5,300 acre-ft). During typical conditions, there are 

3,766 acres of water-surface area that are available for 

recreation. Also, there are 2,733 acres of land surrounding the reservoir that are available for recreational use. Inflow to the reservoir may be affected by 

irrigation return flow from non-Bureau-operated irrigation areas. The Bureau-operated Webster Irrigation 

District No. 4 is located downstream from the reservoir and provides surface-water outflow from the reservoir to irrigate as much as 8,500 acres of farmland 

(Bureau of Reclamation, 1996), generally within 5 mi 

of the South Fork Solomon River.

Waconda Lake, completed in 1967, has a contribr\

uting drainage area of 5,076 mi , with a total storage 

capacity of 963,775 acre-ft of water allocated among 

flood control (722,315 acre-ft), conservation storage 

(204,789 acre-ft), and inactive and dead storage 

(36,671 acre-ft). During typical conditions, there are 

12,602 acres of water-surface area that are available 

for recreation. Also, there are 13,890 acres of land surrounding the reservoir that are available for recreational use. Inflow to Waconda Lake may be affected 

by non-Bureau-operated irrigation areas and the 

Bureau-operated Kirwin Irrigation District No. 1 and 

Webster Irrigation District No. 4. Waconda Lake provides water to irrigate as much as 6,000 acres of farmland in the Bureau-operated Glen Elder Irrigation 

District No. 8, a rural water district, and the city of 

Beloit, Kansas (Bureau of Reclamation, 1996).

Historically, the Solomon River Basin's economy 

centers around agriculture in terms of employment and 

income. Population has been slowly declining over the 

years, particularly among the rural population as 

mechanization of farms and a downsizing of the farm 

economy have eliminated many jobs (Bureau of Reclamation, written commun., 1996). The primary crop

4 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
grown in the basin is wheat, with smaller acreages of 

alfalfa, corn, sorghum, soybeans, and sunflowers. 

Livestock production consists mainly of cattle, with 

lesser numbers of hogs and sheep.

Approximately 3 to 4 percent of the Solomon 

River Basin is irrigated. Water for irrigation in the 

basin comes primarily from ground water upstream 

from Kirwin and Webster Reservoirs (about 87 percent), and primarily from surface water downstream 

from Kirwin and Webster Reservoirs (about 80 percent) (Leonard, 1952; Joan Kenny, U.S. Geological 

Survey, written commun., 1999).

On the basis of 1995 irrigation data, approximately 48 percent of the total irrigated acres downstream from Kirwin, Webster, and Waconda are 

supplied water from Bureau-operated irrigation districts. However, no Bureau irrigation water is used 

upstream from Kirwin and Webster Reservoirs, making Bureau-irrigated acres only 12.1 percent of the 

total number of irrigated acres in the Solomon River 

Basin (table 1).

METHODS

Although a one-time, synoptic sampling may 

define constituent concentrations in the areas of concern, analyzing water quality or shallow bottom-sediment samples collected simultaneously cannot 

document a trend in the deposition of selenium or 

other constituents with time or how the effects of irrigation differ through time. Furthermore, a synoptic 

approach will not provide insight into naturally occurring selenium in sediment deposited in reservoirs prior 

to the onset of major irrigation development. Therefore, the depositional trends of selenium and other 

constituents in this study were determined through 

examination and chemical analysis of layers of

reservoir-bottom sediment that represent the deposition of constituents with time.

Because selenium can be transported on sediment 

derived from marine deposits, a background for naturally occurring concentrations in the reservoir-bottom 

sediment of the Solomon River Basin needs to be 

determined before the effects of irrigation can be 

addressed. Kirwin and Webster Reservoirs were constructed in the early 1950's before irrigation became 

widely practiced. Background is defined as the sediment concentrations of a constituent that are representative of conditions that predate the period of major 

irrigation development in the basin (approximately the 

early to mid-1960's). A comparison of these background concentrations to constituent concentrations 

associated with later deposition will help to assess the 

effect of total (Bureau and non-Bureau) irrigation.

The effect of Bureau irrigation on constituent concentrations can be assessed by comparing constituent 

concentrations and trends in Kirwin and Webster Reservoirs, which do not receive water from Bureau irrigation districts, to constituent concentrations and 

trends in Waconda Lake, which receives water from 

the Bureau-operated Kirwin and Webster Irrigation 

Districts.

Sediment-Core Collection, Processing, 

and Analysis

To determine trends in selenium and other selected 

constituents, bottom-sediment cores were collected in 

May 1998 from two sites each in Kirwin Reservoir, 

Webster Reservoir, and Waconda Lake (fig. 2). The 

two coring sites were compared to assess sampling 

variability at each reservoir. The cores were collected 

in the original channel bed near the dam where the 

sediment is least likely to be disturbed by biological

Table 1. Distribution of irrigated acres in the Solomon River Basin, 1995

[data from Craig Scott, Bureau of Reclamation, written commun., 1998; Joan Kenny, U.S. Geological Survey, written commun., 1999]

Subbasin area

Upstream from Kirwin Reservoir

Downstream from Kirwin Reservoir

Upstream from Webster Reservoir

Downstream from Webster Reservoir

Downstream from Waconda Lake

Total Solomon River Basin

Drainage area 

(acres)

889,248

859,918

744,422

677,761

1,208,109

4,379,458

Irrigated acres

60,600

15,630

51,170

6,940

15,000

149,340

Percentage of 

subbasin area 

irrigated

6.8

1.8

6.9

1.0

1.2

3.4

Bureau of Reclamation irrigated 

acres

0

8,072

0

4,551

5,400

18,023

Methods
99°14' 12' 10'

39°40'

38'

39°36'L

Base from U.S. Geological Survey digital raster graph

Kirwin, 1:24,000,1972

Kirwin Reservoir, 1:24,000,1972

Kirwin SW, 1:24,000,1961

Phillipsburg South. 1:24,000.1972

2 3 MILES

3 KILOMETERS

39°25' -

39°23 -

Base from U.S. Geological Survey digital raster graph rj 

Webster Dam, 1:24,000, photorevised 1997 hNicodemus, 1:24,000,1969 u 

Palco, 1:24,000,1969 

StocktonSW, 1:24,000.1969

99°25'

2 MILES

2 KILOMETERS

EXPLANATION

^ WEB 11 Coring site and identifier 

,-'''" --. Original river channel

Figure 2. Approximate location of sediment-coring sites in (A) Kirwin 

Reservoir, (B) Webster Reservoir, and (C) Waconda Lake.

6 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
c.

39°32'

98°30' 26' 20'

30'

28'

32°26'

Base from U.S. Geological Survey digital raster graph 

Cawker City, 1:24,000, photorevised 1980 

Downs North, 1:24,000, photorevised 1980 

Downs South, 1:24,000, photorevised 1979 

Glen Elder North, 1:24,000, photorevised 1980 

Glen Elder South, 1:24,000, photorevised 1979 

Mill Creek, 1:24,000, photorevised 1979

4 MILES

4 KILOMETERS

EXPLANATION

Coring site and identifier

'~"\_,-''"~^- Original river channel

Figure 2. Approximate location of sediment-coring sites in (A) Kirwin Reservoir, (B) Webster Reservoir, 

and (C) Waconda Lake Continued.

activity, inflows or outflows, human activity, or windinduced currents. A third coring site was sampled in 

Waconda Lake for quality assurance, and nine additional coring sites were sampled in Webster Reservoir 

to determine mass of sediment and selected 

constituents (table 2).

At each coring site, as many as four cores were 

collected using a Benthos gravity corer mounted on a 

pontoon boat (fig. 3A). The liner used in the corer was 

cellulose acetate butylate transparent tubing with a 

2.625-in. inside diameter. Samples were identified first 

by site and then by the order in which they were collected (for example, the cores collected from site 1 in 

Kirwin Reservoir are identified as KIR 1.1, KIR 1.2,

KIR 1.3, and KIR 1.4). All but one core (KIR 2.1 from 

Kirwin Reservoir) penetrated the entire thickness of 

reservoir sediment and into the original channel-bed or 

soil-surface material. Multiple cores were required to 

provide sufficient sediment material for laboratory 

analyses.

For each site, separate cores were analyzed for 

selected physical properties, total recoverable metals, 

nutrients, cesium-137 ( Cs), and total organic carbon. The samples from the nine additional coring sites 

in Webster Reservoir (coring sites WEB 3 through 

WEB 11, table 2) were analyzed for selenium, arsenic, 

strontium, and phosphorus. Selenium and arsenic were 

selected for additional analysis because both are a

Methods
Table 2. Location of bottom-sediment coring sites in the Solomon River Basin, May 1998

Coring-site identifier 

(fig. 2)

U.S. Geological Survey

identification

number

Latitude

(degrees, minutes, 

seconds)

Longitude

(degrees, minutes,

seconds)

KIR1

KIR2

WEB 1

WEB 2

WEB 3

WEB 4

WEB 5

WEB 6

WEB 7

WEBS

WEB 9

WEB 10

WEB 11

WAC1

WAC2

WAC3

Kirwin Reservoir

393942099080400

393942099080100

Webster Reservoir

392349099260500

392403099255000

392410099254200

392330099263600

392335099272000

392339099260200

392300099300300

392411099261500

392346099274000

392312099264300

392307099275700

Waconda Lake

392927098191900

392927098191900

392934098192500

39° 39' 42.90"

39° 39' 42.91"

39° 23' 49.35"

39° 24' 03.88"

39° 24' 10. 12"

39° 23' 30.50"

39° 23' 35.86"

39° 23' 39.24"

39° 23' 00.63"

39° 24' 11. 11"

39° 23' 46.04"

39° 23' 12.31"

39° 23' 07.94"

39° 29' 27.73"

39° 29' 27.50"

39° 29' 34. 19"

99° 08' 04.83"

99° 08' 01.17"

99° 26' 05.35"

99° 25' 50.70"

99° 25' 42. 10"

99° 26' 36.64"

99° 27' 20.78"

99° 26' 02.57"

99° 30' 03.85"

99° 26' 15.00"

99° 27' 40.48"

99° 26' 43.80"

99° 27' 57.05"

98° 19' 19.11"

98° 19' 19.11"

98° 19' 25.84"

concern for human health and because there is a natural source for both constituents (marine strata) in the 

Solomon River Basin. Strontium was selected for 

additional analysis because a previous study in the 

adjacent Republican River Basin identified an increasing trend in strontium concentrations in bottom sediment from three reservoirs (Kyle Juracek, U.S. 

Geological Survey, oral commun., 1998). Phosphorus 

was selected for additional analysis because reservoir 

sediment may contain large quantities of phosphorus 

as a result of inflow transport of paniculate and dissolved forms (Pope, 1998) and because phosphorus 

may accumulate in reservoir sediment (Juracek, 1997).

Processing of core samples and analysis of sediment characteristics were conducted at the USGS laboratory in Lawrence, Kansas. Each core was extracted 

from the liner and split lengthwise to expose the relatively undisturbed inner part of the core for examination and sampling (fig. 35). Depending on the total

sediment thickness, as many as 12 samples were collected from each core. Sediment characteristics that 

were determined included a core description, grain 

size, bulk density, and percentage of moisture. The 

core description involved recording the stratigraphic 

layers of the sediment from the pre-reservoir material 

up to the current depositional layers. The presence of 

pre-reservoir material was determined by a change in 

particle-size composition of the sediment or the presence of organic matter, such as plant material, roots, 

root hairs, sticks, and twigs, that would indicate the 

pre-reservoir soil surface. Grain size, bulk density, and 

moisture percentage were determined according to 

methods presented in Guy (1969).

Chemical constituent analyses were performed by 

the Bureau laboratory in Bismarck, North Dakota, 

using U.S. Environmental Protection Agency 

(USEPA) (U.S. Environmental Protection Agency, 

1997a) and USGS methods (Skougstad and others,

8 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
A.

Figure 3. Photographs showing (A) gravity corer mounted on pontoon boat and (B) core 

preparation.

1979). Microwave-assisted digestion using nitric acid 

(USEPA method 3051) was used on all samples. 

Graphite furnace atomic absorption was used for 

arsenic (USEPA Method 7060A), lead, and selenium 

(USEPA Method 7740). Flame atomic absorption was 

used for strontium (USEPA Method 7780). Cold vapor 

atomic absorption (USEPA Method 7471 A) was used

for mercury. For all other 

metals, inductively coupled 

argon plasma (USEPA 

Method 601 OB) was used. A 

flow injection analyzer was 

used for the analysis of total 

nitrogen (USEPA Method 

350.1) and total phosphorus 

(USGS Method 1-2601-78). 

A carbon analyzer was used 

for the analysis of total 

organic carbon (USEPA 

Method 9060).

To calculate mean and 

median constituent concentrations for samples with 

concentrations less than the 

laboratory detection limit 

and for constituents with 

multiple detection limits, a 

value of one-half the highest 

detection limit reported for 

that constituent in each reservoir was arbitrarily 

assigned. Mean and median 

values were not calculated 

when there were more than 

five samples in a core with 

concentrations less than the 

laboratory detection limits.

Cesium-137 ( 137Cs) 

concentrations were determined by Quanterra Laboratory in Denver, Colorado. 

The concentration of Cs 

was determined to assist in 

age dating the samples. 

137Cs is a radioactive isotope that is a by-product of 

nuclear weapons testing. 

Measurable concentrations 

of this isotope first appeared 

in the atmosphere in about

1952, peaked during 1963-64, and have since declined 

(Holmes, 1998). Cs strongly sorbs to fine-grained 

sediment, making it useful in many studies to age date 

sediment that has been exposed to atmospheric fallout 

(Callender and Robbins, 1993; Van Metre and others, 

1996, 1997; Benninger and others, 1997; Wallbrink 

and others, 1998). It also can be used to demonstrate

Methods
that the sediment is undisturbed if a relatively uniform 

decrease in 137Cs concentration follows the 1963-64 

peak (Pope, 1998).

Quality Control

Without quality-control data, bottom-sediment 

data cannot be interpreted adequately because errors 

associated with sample data are unknown. For this 

study, within-site variability as well as site-to-site variability were determined. Within-site variability of data 

associated with all phases of sample collection and 

analysis was analyzed through the collection of 

sequential, replicate bottom cores from Waconda Lake 

coring site 2 (WAC 2, fig. 2), which was immediately 

adjacent to Waconda Lake coring site 1 (WAC 1, 

fig. 2). The cores from coring site WAC 2 were collected within 15 minutes of collecting the final core 

from coring site WAC 1. The very small change in 

location from site WAC 1 to site WAC 2 (table 2) was 

due to drifting of the pontoon boat.

Cores from coring sites WAC 1 and WAC 2 were 

segmented into 12 sample intervals of various lengths, 

according to changes in physical characteristics 

(fig. 35). Each core segment was homogenized and 

then analyzed for selected physical characteristics, 

total recoverable metals, nutrients, 137Cs, and total 

organic carbon concentrations to provide information 

on the variability of the constituents that were analyzed for all in-channel, near-dam cores. The relative 

percentage difference between the two sample concentrations from coring sites WAC 1 and WAC 2 was 

defined by the following equation:

= (C1-C2)*100 

(C1 + C2) '

(1)

where

RPD = relative percentage difference; 

Cl = larger of two concentration values; and 

C2 = smaller of two concentration values. 

The mean relative percentage differences for all 

total recoverable metals, nutrients, and total organic 

carbon in the sequential replicate samples (coring 

sites WAC 1 and WAC 2) are listed in table 3. The 

mean relative percentage differences for constituent 

concentrations between coring sites WAC 1 and 

WAC 2 ranged from 1.66 percent for manganese to 

8.56 percent for selenium, with a mean relative percentage difference for all constituents of 3.70 percent.

Table 3. Mean relative percentage differences for 

total recoverable metals, nutrients, and total organic 

carbon concentrations in sequential replicate samples 

from bottom-sediment coring sites WAC 1 and WAC 2 

(fig. 2) in Waconda Lake, May 1998

[--, not calculated]

Constituent

Total recoverable metals

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nutrients

Total nitrogen

Total phosphorus

Mean 

relative 

percentage 

difference

2.48

2.53

2.14

-

5.46

3.14

1.71

2.92

1.76

1.66

-

6.22

8.56

3.25

2.68

4.70

5.54

6.12

Organic carbon

Total organic carbon 2.11

A typical quality-control objective for precision of 

replicate samples is a maximum relative percentage 

difference of 20 percent (Taylor, 1987). Not only does 

the sequential replicate bottom-sediment sample represent within-site variability but also includes any 

sample contamination incurred during collection and 

preparation. Percentage differences need to be taken 

into account when evaluating the variability between 

bottom-sediment cores from the same site. It should be 

noted that relative percentage differences were not cal10 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
culated for chemical constituents that were not 

detected and that selenium showed the greatest variability among all constituents that were analyzed. 

Selenium concentrations were close to their method 

detection limit, which may account for their increased 

variability.

No standard method exists for obtaining representative samples of bottom sediment in reservoirs. 

Therefore, to gain some knowledge of the amount of 

variability between sites in the original channel, siteto-site variability was analyzed through the examination of constituent concentrations in samples from two 

coring sites each in Kirwin and Webster Reservoirs. 

The two sites in each reservoir were located in the 

original channel bed near the dam. The two sites in 

Kirwin Reservoir (KIR 1 and KIR 2, fig. 2) were about 

200 ft apart, whereas the two sites in Webster Reservoir (WEB 1 and WEB 2, fig. 2) were about 1,000 ft 

apart. Relative percentage differences were determined using equation 1. Mean relative percentage differences between each site in Kirwin Reservoir for 

total recoverable metals, nutrients, and total organic 

carbon ranged from 2.15 percent for copper to 

11.5 percent for chromium. In Webster Reservoir, the 

differences ranged from 1.91 percent for barium to 

14.2 percent for chromium (table 4). The mean relative 

percentage difference for all constituents in table 4 

was slightly larger for Webster Reservoir (5.85 percent) with sites 1,000 ft apart than for Kirwin Reservoir (5.43 percent) with sites 200 ft apart. On the basis 

of these comparisons, there is not substantial variability in sediment chemistry even over the fairly large 

distance between sampling sites.

Trend Analysis

Spearman's rho (r) correlation and Kendall's 

tau (T) trend tests were done for sediment concentrations in cores from each reservoir. Both tests were 

used because each offered a possible advantage over 

the other. Spearman's rho gives more weight to differences between data values ranked farther apart than 

does Kendall's tau. Spearman's rho was computed 

according to methods presented in Helsel and Hirsch 

(1992). Core-sample intervals were normalized by 

dividing the distance from the bottom of the core to 

the center of the sample by the total core length. Concentrations of selected constituents were paired with 

their associated normalized depth interval to determine a positive (constituent concentrations increasing

Table 4. Mean relative percentage differences 

for total recoverable metals, nutrients, and total 

organic carbon concentrations in bottom-sediment 

samples from Kirwin and Webster Reservoirs, May 

1998

[--, not calculated]

Mean relative percentage 

difference

Constituent

Kirwin Reservoir coring 

sites KIR 1 

and KIR 2

(fig. 2)

Total recoverable metals 

Aluminum 9.29

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Total nitrogen

Total phosphorus

Total organic carbon

3.97

2.30

6.13

_

11.5

2.15

4.48

4.47

4.59

2.45

-

5.90

10.2

3.40

10.9

3.99

Nutrients

4.47

4.85

Organic carbon

2.73

Webster Reservoir coring 

sites WEB 1 

and WEB 2

(fig. 2)

8.88

2.70

1.91

--

8.31

__

14.2

2.05

4.67

5.29

5.07

3.79

--

5.60

6.56

3.66

9.98

3.29

11.2

5.36

2.73

with decreasing depth) or negative correlation (constituent concentrations decreasing with decreasing depth). 

Kendall's tau was calculated according to methods 

described in Hirsch and others (1993). Kendall's tau is 

a nonparametric trend test that is rank based and, 

therefore, resistant to the effects of extreme values and 

to derivations from a linear relation (Hirsch and othMethods 11
ers, 1993). Kendall's tau may be more appropriate 

than Spearman's rho for sample sizes less than 20 

(Helsel and Hirsch, 1992).

Rho and tau were not calculated for cores having 

more than five samples with concentrations less than 

the detection limit. Trends were considered positive if 

either test (Spearman's rho or Kendall's tau) was significant, with p values less than 0.05 (p<0.05) in both 

cores from Kirwin and Webster Reservoirs or two of 

the three cores from Waconda Lake. Only those constituents that met the above criteria in more than one 

reservoir (selenium, arsenic, and strontium) will be 

discussed in detail later in this report. The p values discussed later in this report will be those associated with 

the Kendall's tau trend test.

RESULTS OF RESERVOIR BOTTOMSEDIMENT ANALYSIS

Sediment-Core Lithology and Grain Size

The length of sediment cores collected as part of 

this study ranged from 1.4 to 8.0 ft (table 9 in "Supplementary Information" section). The cores from all 

three lakes appeared stratified, with alternating dark 

and light layers. These layers became less distinct at 

the top of the core. The deeper stratified layers could 

be correlated easily among the cores; the shallower 

layers were less easily correlated. This may account 

for a larger variance among concentrations of selected 

constituents in shallower sediment samples as compared to the deeper samples. In addition, the deeper 

layers tended to be thicker.

Before a comparison could be made between the 

length of the cores collected and the Bureau's sedimentation data, the effect of core shortening had to be 

determined. Core shortening is a phenomenon associated with the use of a gravity corer and has been estimated to shorten the core by as much as 50 percent 

(Emery and Hulsemann, 1964). Core shortening also 

has been observed in a previous study in Kansas that 

collected sediment using a gravity corer (Juracek, 

1997). Hongve and Erlandsen (1979) attribute the 

shortening to compression of sediment and loss of 

water content. This shortening effect also has been 

attributed to the effects of friction of the sediment 

against the inner wall of the core liner (Emery and 

Deitz, 1941; Blomqvist and Bostrom, 1987). There is 

also the possibility that the core-shortening phenomenon is due to a loss of sediment from the core column. 

If this occurs, there may be an effect on bulk density 

and related calculations.

In this study, the amount of core shortening was 

determined by measuring the distance from the water 

surface to the top of the sediment with a weighted tape 

and confirming this distance with a depth finder. When 

the gravity corer was released into the reservoir, the 

distance from the water surface to the tip of the gravity 

corer was determined by marking and measuring the 

distance against the cable holding the coring device. 

The difference between this depth and the depth to the 

sediment (as measured by weighted tape) was determined to be the thickness of sediment, in situ. Once 

the sediment core was retrieved, its length was measured, and this was divided by the thickness of sediment and multiplied by 100 to determine the recovery 

percentage (table 5). In most cases, any original channel-bed or land-surface material in the liner was less 

than 0.1 ft and did not affect the calculation of the 

recovery percentage. The average recovery percentage 

for cores from all three reservoirs was 68 percent. 

Table 9 in the "Supplemental Information" section at 

the end of this report includes lengths of all cores collected during this study, unconnected for original channel-bed or land-surface material thickness or core 

shortening.

The lengths of cores KIR 1.4 and KIR 2.1 used for 

analysis of core lithology and grain size from Kirwin 

Reservoir were 7.9 and 3.2 ft, respectively (table 9). 

Core KIR 2.1 was the only core collected during the 

study that did not reach original land-surface material, 

which accounts for the shorter core length. When visually compared to the other three cores collected from 

coring site KIR 2, it was evident that the deepest three 

samples were missing from core KIR 2.1. The percentage of silt and clay was equal to or greater than 

97.7 percent in all samples from both Kirwin cores 

(table 10 in "Supplemental Information" section). The

Table 5. Sediment-recovery percentages

in cores collected from Kirwin Reservoir, Webster

Reservoir, and Waconda Lake, May 1998

[--, not determined]

Sediment recovery (percent)

Reservoir

Kirwin Reservoir 

Webster Reservoir 

Waconda Lake

In-channel

64.0

74.3 

48.3

Out-ofchannel

82.5

12 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
mean percentages of silt and clay determined for 

coring sites KIR 1 and KIR 2 were 99.4 and 99.5 percent, respectively (table 6). The mean percentage of 

sand was less than 1.0 percent for both coring sites. 

Bulk densities for samples from cores KIR 1.4 and 

KIR 2.1 ranged from 27.5 to 50.4 lb/ft3 (table 10), 

with the larger bulk density in samples from the bottom (deeper) parts of each core. The percentage of 

moisture in samples from cores KIR 1.4 and KIR 2.1 

ranged from 46.8 to 65.5 percent, with the shallower 

(top) samples having a larger percentage of moisture 

(table 10).

The lengths of cores WEB 1.1 and WEB 2.1 used 

for the analysis of core lithology and grain size for 

Webster Reservoir were 7.0 and 7.2 ft, respectively 

(table 9). The smallest percentage of silt and clay in all 

samples was 98.9 percent, and the percentage of sand 

in all samples was less than or equal to 1.1 percent 

(table 10). Bulk density ranged from 21.1 to 48.6 lb/ft3 

(table 10). Mean bulk-density values for the two cores 

were 35.4 and 34.8 lb/ft3 (table 6). Larger bulk-density 

values generally occurred in the deeper samples. The 

percentage of moisture ranged from 46.6 to 72.9 percent, with samples at the top of the cores generally 

having a larger percentage of moisture (table 10). The 

additional cores collected in Webster Reservoir, 

because they were collected both in and out of the 

original channel bed, had a wider range in grain size, 

bulk density, and percentage of moisture. In general, 

grain sizes and bulk-density values were larger in outof-channel cores as compared to in-channel cores, and

Table 6. Mean percentage of silt and clay, percentage 

of sand, bulk density, and percentage of moisture in 

bottom-sediment samples from coring sites in Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, 

May 1998

[lb/ft3 , pound per cubic foot]

Coring- Mean per- Mean

site iden- centage Mean per- Mean bulk percenttifier of silt centage density age of

(fig. 2) and clay of sand (lb/ft3) moisture

KIR1

KIR 2

WEB 1

WEB 2

WAC1

WAC3

99.4

99.5

99.8

99.8

99.8

99.9

0.6

.5

.2

.2

.2

.1

40.6

37.7

35.4

34.8

32.5

29.2

55.3

56.9

57.3

61.2

59.9

64.1

the percentage of moisture was smaller in out-ofchannel cores.

The lengths of cores WAC 1.1 and WAC 3.2 used 

for the analysis of core lithology and grain size for 

Waconda Lake were 6.1 and 7.0 ft, respectively 

(table 9). The percentage of silt and clay in samples 

from both cores was greater than 99 percent, with less 

than 1 percent sand (table 10). Bulk density ranged 

from 21.6 to 47.0 lb/ft3 , with larger bulk-density values generally occurring in deeper samples (table 10). 

The percentage of moisture ranged from 46.3 to 73.1, 

with shallower samples generally having a larger percentage of moisture.

The cores from Kirwin, Webster, and Waconda 

that were collected within the channel and near the 

dam had mean percentages of silt and clay greater than 

99 percent (table 6). In-channel core bulk-density values were generally larger in deeper samples, and the 

percentage of moisture was generally smaller when 

compared to shallower samples. The cores from Webster Reservoir that were collected outside of the original channel bed (coring sites WEB 6 through 

WEB 11) generally had larger sand percentages, larger 

bulk-density values, and smaller moisture percentages 

when compared to samples from in-channel cores.

Age Dating and Depositional Patterns of 

Bottom Sediment

Kirwin Reservoir, the oldest of the three reservoirs 

in the basin, was completed in 1952. This completion

1 ^*7 date coincides with the first occurrence of Cs in the 

atmosphere. Therefore, the date of deposition of the 

sediment in the bottom of cores from Kirwin Reservoir was assumed to be 1952 (fig. 4). To make comparisons between coring sites and among the different 

reservoirs, core-sample intervals were normalized. 

The peak in 137Cs concentration in sediment cores 

KIR 1.2 and KIR 2.3 from Kirwin Reservoir occurred 

near the normalized sample interval of 0.5 (dimensionless) (fig. 4). The date 1963-64, the peak of 137Cs 

atmospheric deposition (Holmes, 1998), was assigned 

to this interval. The Cs concentration following the 

peak shows a smooth decline in concentration, which 

would indicate that the sediment has been relatively 

undisturbed by biological activity, inflows or outflows, 

human activity, or wind-induced currents. One additional date, the date of sampling (1998), was assigned 

to the top of the core.

Results of Reservoir Bottom-Sediment Analysis 13
Kirwin Reservoir core KIR 1.2 Kirwin Reservoir core KIR 2.3

Cfl w

_Q)

c 

o 'c/>

c

CD

^ 

05

O 

O

M 

O

Q. 

O

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

 1998

1963-64 1963-64

Webster Reservoir core WEB 1.3 Webster Reservoir core WEB 2.3

 1998

1963-64 1963-64

M956

Q.

E 

3 1.0

-o

Q) no _N 0.9 "co 

E 0.8

o

Z 0.7

0.6

0.5

0.4

0.3

0.2

0.1

n

Waconda Lake core WAC 1.2

{4

<

-

-

-

1998

»

t

>

{

\

1

Il967

Waconda Lake core WAC 2.2

 1998

_t

T

- T

- 0

* '

- \

- V

- 1

y41967

Waconda Lake core WAC 3.4

\

41967

1.0 2.0 3.0 0 1.0 2.0 3.0 0 1.0 

Cesium-137 concentration, in picocuries per gram

2.0 3.0

Figure 4. Depth-normalized cesium-137 profiles in selected bottom-sediment cores collected in May 1998 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake. Location of coring sites shown in figure 2.

14 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Given the above dates, it may be possible to calculate depositional rates for sediment before 1963-64 

and after 1964. However, these depositional rates may 

be misleading because of the core-shortening phenomenon discussed in the previous section. Because the 

cause of the core shortening is unknown, it is not possible to accurately correct for it. Additionally, 

although it is possible to verify that the entire sediment 

thickness has been penetrated and the deepest layers 

are present, it is not possible to verify that the shallowest layers are present. Because the gravity corer 

descends with great force, it may shift the shallowest, 

less consolidated layers so that they are not recovered 

in the core liner. Therefore, average depositional rates 

calculated on the basis of core length are not presented 

herein, but depositional patterns as they relate to reservoir inflows are discussed in more general terms.

In Kirwin Reservoir, it appears from the 137Cs 

profiles (cores KIR 1.2 and KIR 2.3, fig. 4) that the 

1963-64 peak is at approximately the center of each 

core. Because the normalized sample intervals

between 0 and 0.5 represent approximately the first 

12 years of sediment deposition and the normalized 

sample intervals between 0.5 and 1.0 represent 

approximately 34 years of sediment deposition, one 

might conclude that the depositional rate prior to 

1963-64 was more than twice the depositional rate 

after 1964. However, because of the core shortening 

and recovery phenomena discussed previously, a depositional rate cannot be accurately established. There is 

evidence, however, that indicates that deposition was, 

in fact, greater in the early years of the reservoir. A 

visual examination of the cores from Kirwin Reservoir 

reveals thick layers of sediment in the deepest intervals. This is consistent with other reservoir studies 

(Ritchie and others, 1986; Callender and Robbins, 

1993), which demonstrated that sedimentation rates 

decreased with reservoir age. Historical streamflow 

data for the inflow to Kirwin Reservoir indicate that 

much of the early sediment deposition in the lake may 

have been caused by floods during the 1957 and 1960 

water years (fig. 5).

Inflow to Kirwin Reservoir Inflow to Webster Reservoir Inflow to Waconda Lake

2000

1990

1980

1970

1960

1950

Combined annual discharge 

at USGS gaging stations 

06871000 and 06871500

Annual discharge at USGS 

gaging station 06873000

Combined annual discharge 

at USGS gaging stations 

06872500 and 06874000

0 20 40 60 80 100120140160180 0 20 40 60 80100120140160180200 0 200 400 600 8001,0001,2001,400

Mean annual discharge (all days), in cubic feet per second

Figure 5. Historical inflows to Kirwin Reservoir, Webster Reservoir, and Waconda Lake. Data from U.S. Geological 

Survey (USGS) streamflow-gaging stations 06871000 and 06871500 upstream from Kirwin Reservoir, station 

06873000 upstream from Webster Reservoir, and stations 06872500 and 06874000 upstream from Waconda Lake. 

Data on file with the U.S. Geological Survey, Lawrence, Kansas. The location of these streamflow-gaging stations is 

shown in figure 1.

Results of Reservoir Bottom-Sediment Analysis 15
Webster Reservoir was completed in 1956, and

1 0*7

although the first atmospheric deposition of Cs cannot be assigned, the 1963-64 peak is evident near the 

0.5 sample interval (fig. 4). As with Kirwin Reservoir, 

the 137Cs concentration following the 1963-64 peak 

shows a relatively smooth decline, indicating presumably undisturbed sediment. The top of the cores may 

be assigned a date of 1998 (the date of sampling). The 

cores from Webster Reservoir (cores WEB 1.3 and 

WEB 2.3, fig. 4) also showed thicker layers of sediment in the deeper samples compared to the shallower 

samples. Similar to data derived from cores from Kirwin Reservoir, the greater sedimentation rate of the 

initial deposits in Webster Reservoir may have been 

caused by floods in the 1957, 1960, and 1962 water 

years (fig. 5).

Because Waconda Lake was completed in 1967,

1 ^7 neither the first incidence of Cs (in 1952) nor the 

peak (1963-64) is evident in sediment cores WAC 1.2, 

WAC 2.2, and WAC 3.4 from Waconda Lake (fig. 4). 

The only dates that can be assigned to the cores from 

Waconda Lake are the date of dam completion (1967) 

to the bottom of the core and the sampling date (1998) 

to the top of the core. However, a relatively smooth

1 ^7 decrease in . Cs concentrations is evident for the 

three sediment cores. This would indicate that the bottom sediment has been relatively undisturbed. Upon 

visual examination of the Waconda Lake cores 

(WAC 1.2, WAC 2.2, and WAC 3.4, fig. 4), it appears 

that there also was significant sedimentation in the 

early years of the reservoir, as indicated by a very 

thick sedimentation layer in the deepest core samples. 

This may be due to large inflows in 1969 and 1974 

(fig. 5).

In addition to large inflows in the years following 

reservoir completion, the greater sedimentation rates 

observed in the three reservoirs before 1964 may be 

due, in part, to other factors. These include a change in 

sediment source, changes in land use, or the development of small-scale impoundments or reservoirs 

within the basin that trap sediment before it reaches 

Kirwin Reservoir, Webster Reservoir, and 

Waconda Lake.

Concentrations and Trends in Selected 

Chemical Constituents

The U.S. Environmental Protection Agency 

(USEPA) has established sediment-quality guidelines 

in the form of level-of-concern concentrations for several trace metals (U.S. Environmental Protection 

Agency, 1997b). These level-of-concern concentrations were derived from biological-effects correlations 

made on the basis of paired onsite and laboratory data 

to relate incidence of adverse biological effects to dryweight sediment concentrations. Two such level-ofconcern concentrations presented by USEPA are 

referred to as the threshold-effects level (TEL) and the 

probable-effects level (PEL). The smaller of the two 

guidelines (the TEL) is assumed to represent the concentration below which toxic effects rarely occur. In 

the range of concentrations between the TEL and PEL, 

adverse effects occasionally occur. Toxic effects usually or frequently occur at concentrations above the 

larger guideline (the PEL).

The TEL and PEL are guidelines to be used as 

screening tools for possible hazardous levels of chemicals and are not regulatory criteria. The USEPA 

(1997b) has made this cautionary statement because, 

although biological-effects correlation identifies levelof-concern concentrations associated with the likelihood of adverse organism response, the procedure 

does not demonstrate that a particular chemical is 

solely responsible.

Table 7 shows a statistical summary of selected 

chemical constituents analyzed in bottom-sediment 

samples from the three Solomon River Basin reservoirs. Concentrations of selenium, arsenic, strontium, 

and phosphorus in samples from the additional cores 

collected from Webster Reservoir (coring sites 

WEB 3-11) are not included. The USEPA (1997b) has 

established TELs and PELs for eight of the constituents listed. The median arsenic and copper concentrations exceeded the TELs for samples from all three 

reservoirs. Cadmium concentrations exceeded the 

TEL in four samples from Kirwin and Webster Reservoirs. Nickel concentrations exceeded the TEL in 

11 samples from Webster Reservoir. Concentrations of 

chromium, lead, and mercury either were not detected 

or did not exceed TELs in samples from any reservoir. 

PELs were not exceeded for any of the eight constituents in samples from any of the three reservoirs.

Increasing trends in selenium, arsenic, manganese, 

strontium, and phosphorus concentrations, determined 

using Spearman's rho correlation and Kendall's tau 

trend test, occurred in bottom-sediment samples from 

at least one reservoir (table 8). Decreasing trends in 

aluminum and magnesium concentrations occurred in 

bottom-sediment samples from Webster Reservoir. 

Decreasing trends in iron concentrations occurred in

16 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 7. Statistical summary of selected constituent concentrations in bottom-sediment samples from Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, May 1998, and comparison to sediment-quality guidelines

[mg/kg, milligrams per kilogram; --, not determined; <, less than highest detection limit for samples from that reservoir]

Concentrations in bottom-sediment cores (mg/kg)

Sediment-quality 

guidelines1

Constituent

Kirwin Reservoir

Range Median

Webster Reservoir

Range Median

Waconda

Range

Lake

Median TEL PEL

TVace metals

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

13,500-54,300

4.6-10

216-362

<2.7

<21-37

<2.7-3.7

9-33

17-28

14,200-33,900

14-26

4,370-10,500

371-573

<0.2

< 11-24

<0.5-2.2

74-219

23-114

59-118

1,200-1,980

422-795

33,400

8.0

303

-

27.5

-.

16

22

25,000

21

7,460

496

-

12

1.0

149

82

93.5

1,700

616

18,300-54,200

8.0-15.1

224-333

<3. 1-4.8

<24-37

<3.0

<6-26

19-29

16,900-33,100

16-32

5,740-10,900

341-788

<0.2

<12-30

0.5-2.7

109-263

47-125

76-119

30.0-1,910

251-692

31,300

11

285

-

18

-.

13

25

24,900

26

7,890

541

-

14

1.4

177

64

98

Nutrients

1,640

562

15,000-50,900

5.4-13.1

155-372

<5.1

<41-47

<5.1

<10-17

7-27

9,200-27,100

< 14-25

2,260-7,260

235-1,110

<0.2

<21

<0.6-3.4

68-336

22-73

35-137

704-3,210

281-904

26,100

10.2

276

-

-

10

22

23,700

18

5,910

770

-

--

1.1

154

58

102

2,050

652

..

7.24 41.6

..

-

-

.68 4.21

52.3 160

18.7 108

-

30.2 112

..

--

.13 .696

15.9 42.8

-

.-

-

124 271

-

--

Organic carbon

Total

organic 

carbon

8,310-13,600 11,600 10,600-16,200 12,300 3,440-19,900 16,700 -

'Sediment-quality guidelines from U.S. Environmental Protection Agency (1998): 

TEL threshold-effects level; 

PEL probable-effects level.

bottom-sediment samples from Kirwin and Webster 

Reservoirs. No increasing or decreasing trends 

occurred in concentrations of barium, beryllium, 

boron, cadmium, chromium, copper, lead, nickel, 

vanadium, zinc, nitrogen, or total organic carbon. Mercury was not detected in bottom sediment from any of 

the three reservoirs in the basin. Of the chemical constituents analyzed in core samples from the three reservoirs, arsenic, selenium, and strontium were the only 

constituents that showed an increasing trend in concentrations in samples from more than one reservoir.

Selenium

The USEPA has not established a threshold-effects 

level (TEL) or probable-effects level (PEL) for selenium. However, concentrations equal to or greater than

Results of Reservoir Bottom-Sediment Analysis 17
Table 8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998

[--, not calculated]

Coresample identification Constituent

Total 

number 

of samples

Number 

of samples with 

detections

Spearman's 

rho (r)

Trend test at a 

0.05 level of 

significance

Kendall's 

tau (T)

Trend test at a 

0.05 level of 

significance

Kirwin Reservoir bottom-sediment cores (fig. 2A)

KIR1.3

KIR2.2

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

1

8

0

12

12

12

12

12

12

0

9

11

12

12

12

12

12

12

12

12

12

4

11

3

12

12

12

12

12

12

0

10

0.615

.280

-.294

-

.638

-

.323

-.396

-.399

-.088

-.378

.137

-

-.539

.749

.958

.739

-.415

-.350

.846

-.259

-.322

-.414

-.392

--

-.525

-

-.334

-.551

-.797

-.514

-.818

.496

-

-.234

increasing trend

no trend

no trend

-

increasing trend

-

no trend

no trend

no trend

no trend

no trend

no trend

-

no trend

increasing trend

increasing trend

increasing trend

no trend

no trend

increasing trend

no trend

no trend

no trend

no trend

--

no trend

-

no trend

no trend

decreasing trend

no trend

decreasing trend

no trend

-

no trend

0.364

.182

.212

-

.333

-

.167

.348

-.394

-.061

-.364

.015

-

-.379

.561

.909

.500

-.439

-.242

.667

-.212

-.273

-.333

-.333

~

-.379

-

-.258

-.439

-.667

-.394

-.697

.424

-

-.182

no trend

no trend

no trend

-

no trend,

-

no trend

no trend

decreasing trend

no trend

no trend

no trend

-

decreasing trend

increasing trend

increasing trend

increasing trend

decreasing trend

no trend

increasing trend

no trend

no trend

no trend

no trend

-

decreasing trend

-

no trend

decreasing trend

decreasing trend

decreasing trend

decreasing trend

increasing trend

-

no trend

18 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample identification Constituent

Total 

number 

of samples

Number 

of samples with 

detections

Spearman's 

rho (r)

Trend test at a 

0.05 level of 

significance

Kendall's 

tau (t)

Trend test at a 

0.05 level of 

significance

Kirwin Reservoir bottom-sediment cores (fig. 24) Continued

KIR2.2 Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

12

12

12

12

12

12

12

11

12

12

12

12

12

12

0.313

.657

.119

-.343

.427

.893

-.308

no trend

increasing trend

no trend

no trend

no trend

increasing trend

no trend

0.227

.485

.091

-.273

.303

.692

-.242

no trend

increasing trend

no trend

no trend

no trend

increasing trend

no trend

Webster Reservoir bottom-sediment cores (fig. 2B)

WEB 1.2

WEB 2.4

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

Aluminum

Arsenic

Barium

Beryllium

Boron

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

10

10

1

11

12

12

12

12

12

0

9

12

12

12

12

12

12

12

12

12

12

0

4

-.573

.641

-.420

-.242

-.222

-

-.565

-.364

-.517

.134

-.510

.888

-

-.531

.569

.888

-.354

-.457

-.112

.496

-.196

-.727

.669

-.900

-

no trend

increasing trend

no trend

no trend

no trend

-

no trend

no trend

no trend

no trend

no trend

increasing trend

-

no trend

no trend

increasing trend

no trend

no trend

no trend

no trend

no trend

decreasing trend

increasing trend

decreasing trend

~

-.485

.530

-.333

-.121

-.197

-

-.424

-.333

-.485

.015

-.455

.788

-

-.364

.409

.758

-.258

.348

-.364

-.167

.091

-.576

.530

-.773

-

..

decreasing trend

increasing trend

no trend

no trend

no trend

--

decreasing trend

no trend

decreasing trend

no trend

decreasing trend

increasing trend

-

no trend

increasing trend

increasing trend

no trend

no trend

no trend

no trend

no trend

decreasing trend

increasing trend

decreasing trend

-

Results of Reservoir Bottom-Sediment Analysis 19
Table 8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample identification Constituent

Total 

number 

of samples

Number 

of samples with 

detections

Spearman's 

rho (r)

Trend test at a 

0.05 level of 

significance

Kendall's 

tau (T)

Trend test at a 

0.05 level of 

significance

Webster Reservoir bottom-sediment cores (fig. 2B) Continued

WEB 2.4 Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

0

10

12

12

12

12

12

0

7

12

12

12

12

12

12

12

--

-0.711

-.664

-.769

-.462

-.692

.956

-

-.687

.874

.937

.042

-.585

-.186

.052

.021

-

decreasing trend

decreasing trend

decreasing trend

no trend

decreasing trend

increasing trend

--

decreasing trend

increasing trend

increasing trend

no trend

decreasing trend

no trend

no trend

no trend

--

-0.515

-.455

-.606

-.333

.-.318

.864

-

-.485

.697

.848

0

-.424

-.106

.136

0

-

decreasing trend

decreasing trend

decreasing trend

no trend

no trend

increasing trend

-

decreasing trend

increasing trend

increasing trend

no trend

decreasing trend

no trend

no trend

no trend

Waconda Lake bottom-sediment cores (fig. 2C)

WAC 1.3 Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

0

2

0

10

12

12

11

12

12

0

5

10

12

12

12

12

.594

.734

.400

-

-

-

-.407

-.218

.531

-.050

.601

.189

-

-

.550

.818

.451

.287

.063

increasing trend

increasing trend

no trend

-

-

-

no trend

no trend

no trend

no trend

increasing trend

no trend

--

-

no trend

increasing trend

no trend

no trend

no trend

.455

.515

.303

-

-

-

-.273

-.091

.394

-.061

.485

.136

-

--

.364

.576

.348

.152

.030

increasing trend

increasing trend

no trend

-

-

-

no trend

no trend

increasing trend

no trend

increasing trend

no trend

-

--

no trend

increasing trend

no trend

no trend

no trend

20 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample identification Constituent

Total 

number 

of samples

Number 

of samples with 

detections

Spearman's 

rho (r)

Trend test at a 

0.05 level of 

significance

Kendall's 

tau (r)

Trend test at a 

0.05 level of 

significance

Waconda Lake bottom-sediment cores (fig. 2C) Continued

WAG 1.3

WAC2.1

WAC3.1

Phosphorus

Total organic 

carbon

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

Aluminum

Arsenic

Barium

Beryllium

Boron

Cadmium

Chromium

Copper

Iron

Lead

Magnesium

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

0

4

0

11

12

12

11

12

12

0

8

12

12

12

12

12

12

12

12

12

12

0

8

0

11

12

12

12

12

0.161

-.322

-.441

.154

-.472

-

-

-.733

-.604

-.510

-.477

-.203

-.112

-

-.714

.519

.854

-.431

-.685

.510

-.196

-.818

 *

.412

.768

.448

-

.564

~

.039

.046

.350

.042

.434

no trend

no trend

no trend

no trend

no trend

-

-

-

decreasing trend

decreasing trend

no trend

no trend

no trend

no trend

-

decreasing trend

no trend

increasing trend

no trend

decreasing trend

no trend

no trend

decreasing trend

no trend

increasing trend

no trend

~

increasing trend

--

no trend

no trend

no trend

no trend

no trend

0.121

-.182

-.394

.121

-.288

-

-

-

-.606

-.439

-.455

-.333

-.273

-.030

-

-.515

.424

.742

-.348

-.515

.303

-.106

-.576

.333

.636

.273

-

.409

~

-.015

-.015

.303

-.015

.333

no trend

no trend

decreasing trend

no trend

no trend

--

-

-

decreasing trend

decreasing trend

decreasing trend

no trend

no trend

no trend

-

decreasing trend

increasing trend

increasing trend

no trend

decreasing trend

no trend

no trend

decreasing trend

no trend

increasing trend

no trend

-

increasing trend

-

no trend

no trend

no trend

no trend

no trend

Results of Reservoir Bottom-Sediment Analysis 21
Table 8. Results of trend tests on concentrations of selected constituents in bottom-sediment cores collected 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample identification Constituent

Total 

number 

of samples

Number 

of samples with 

detections

Spearman's 

rho (r)

Trend test at a 

0.05 level of 

significance

Kendall's 

tau (T)

Trend test at a 

0.05 level of 

significance

Waconda Lake bottom-sediment cores (fig. 2Q Continued

WAC3.1 Manganese

Mercury

Nickel

Selenium

Strontium

Vanadium

Zinc

Nitrogen

Phosphorus

Total organic 

carbon

12

12

12

12

12

12

12

12

12

12

12

0

2

11

12

12

12

12

12

12

.718

--

-

.874

.238

.656

.196

.895

.860

.049

increasing trend

--

--

increasing trend

no trend

increasing trend

no trend

increasing trend

increasing trend

no trend

.591

--

--

.727

.197

.545

.061

.758

.121

0

increasing trend

--

--

increasing trend

no trend

increasing trend

no trend

increasing trend

increasing trend

no trend

4.0 mg/kg (milligrams per kilogram) in sediment are a 

concern because of the potential for bioaccumulation 

in fish and wildlife (Lemly and Smith, 1987).

In Kirwin Reservoir, selenium concentrations in 

samples from bottom-sediment cores ranged from less 

than 0.3 to 2.2 mg/kg (table 11 in "Supplemental 

Information" section). A significant increasing trend 

(p=0.006) was evident in only one of the two Kirwin 

cores (core KIR 1.3, fig. 6). In Webster Reservoir, the 

selenium concentrations in bottom-sediment cores 

ranged from 0.3 to 4.0 mg/kg (table 11). A significant 

increasing trend (p=0.001 and p=0.035) occurred in 

both Webster bottom-sediment cores. In Waconda 

Lake, selenium concentrations in samples from bottom-sediment cores ranged from less than 0.4 to 

3.4 mg/kg (table 11). Significant increasing trends 

were evident in two of the three cores (cores WAC 2.1, 

p=0.031, and WAC 3.1, p=0.001). Core WAC 1.3 had 

a p value slightly higher than the specified criteria 

(p=0.052).

Arsenic

Arsenic has been used in the past as a compound 

in pesticides and also may be the result of some industrial activities (Pais and Jones, 1997). Because arsenic 

is believed to be carcinogenic, the USEPA (1997b) has 

established a threshold-effects level (TEL) of 

7.24 mg/kg and a probable-effects level (PEL) of 

41.6 mg/kg.

In Kirwin Reservoir, arsenic concentrations in 

samples from bottom-sediment cores ranged from 

4.6 to 10 mg/kg (table 11 in "Supplemental Information" section). In Webster Reservoir, arsenic concentrations in bottom-sediment cores ranged from 8.0 to 

15.1 mg/kg (table 11). In Waconda Lake, arsenic concentrations in bottom-sediment cores ranged from 

5.4 to 13.1 mg/kg (fig. 7, table 11). A significant 

increasing trend in arsenic concentrations was not evident in the Kirwin cores. There was, however, an 

increasing trend in the cores from Webster Reservoir 

(core WEB 1.2, p=0.010, and core WEB 2.4, p=0.010) 

and Waconda Lake (core WAC 1.3, p=0.012, and core 

WAC3.1,p=0.002).

Strontium

Strontium is common in the lithosphere, and its 

geochemical and biochemical characteristics are similar to calcium (Pais and Jones, 1997). There are no 

TEL and PEL guidelines for strontium.

Strontium concentrations in core samples from 

Kirwin Reservoir ranged from 74 to 219 mg/kg 

(table 11 in "Supplemental Information" section) and 

showed a significant increasing trend in both cores 

(p=0 and p=0.017) (fig. 8). Strontium concentrations 

ranged from 109 to 263 mg/kg in cores WEB 1.2 and 

WEB 2.4 from Webster Reservoir (table 11) and 

showed a significant increasing trend (p=0). Strontium 

concentrations in Waconda cores WAC 1.3, WAC 2.1,

22 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Kirwin Reservoir core KIR 1.3 Kirwin Reservoir core KIR 2.2

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c 0

E

T3

£ 

O 

O

Ho

Q. 

O

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

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1963-64

Webster Reservoir core WEB 1.2

1956

Waconda Lake core WAC 1.3

a 1.0

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

1963-64

r1952

j_____i_____i

Webster Reservoir core WEB 2.4

Waconda Lake core WAC 2.1 Waconda Lake core WAC 3.1

1967

j____i____i

0 1.0 2.0 3.0 4.0 0 1.0 2.0 3.0 4.0 0

Selenium concentration, in milligrams per kilogram

1.0 2.0 3.0 4.0

Figure 6. Depth-normalized selenium concentration profiles in selected bottom-sediment cores collected in 

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake.

Results of Reservoir Bottom-Sediment Analysis 23
Kirwin Reservoir core KIR 1.3 Kirwin Reservoir core KIR 2.2

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

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Webster Reservoir core WEB 1.2

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Waconda Lake core WAC 1.3

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0.8 

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0.4 

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1998

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Webster Reservoir core WEB 2.4

Waconda Lake core WAC 2.1 Waconda Lake core WAC 3.1

i i r 

1998-

r' 1967 . 1967

10 15 20 05 10 15 20 0 

Arsenic concentration, in milligrams per kilogram

10 15 20

Figure 7. Depth-normalized arsenic concentration profiles in selected bottom-sediment cores collected in 

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake.

24 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Kirwin Reservoir core KIR 1.3 Kirwin Reservoir core KIR 2.2

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o 0.7

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

1963-64

Waconda Lake core WAC 1.3

| 1 '°

03

E 0.9

o

Z 0.8

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0

 1998

H963-64

Webster Reservoir core WEB 2.4

1963-64

Waconda Lake core WAC 2.1

i i r 

1998.

Waconda Lake core WAC 3.1

1998

'0 100 200 300 400 0 100 200 300 400 0

Strontium concentration, in milligrams per kilogram

100 2.0 300 400

Figure 8. Depth-normalized strontium concentration profiles in selected bottom-sediment cores collected in 

May 1998 from Kirwin Reservoir, Webster Reservoir, and Waconda Lake.

Results of Reservoir Bottom-Sediment Analysis 25
and WAC 3.1 ranged from 68 to 336 mg/kg (table 11). 

Two of the three bottom-sediment cores from 

Waconda Lake had significant increasing trends (core 

WAC 1.3, p=0.005, and core WAC 2.1, p=0.001).

Nutrients and Total Organic Carbon

Nutrients, such as nitrogen and phosphorus, are 

necessary for growth and reproduction of plants. In 

general, major sources of nutrients include fertilizer 

application, livestock production, and sewage-treatment plants. There are no TEL and PEL guidelines for 

nitrogen or phosphorus. Total organic carbon (TOC), 

an approximate determination of total organic material 

in a sediment sample, is important because various 

organic solutes can form complexes, which in turn 

affect metal solubilities (Hem, 1992). There are no 

TEL and PEL guidelines for TOC.

The median nitrogen concentration in core samples from Kirwin Reservoir was 1,700 mg/kg, compared to 1,640 mg/kg in samples from Webster 

Reservoir and 2,050 mg/kg in samples from Waconda 

Lake. Core WAC 3.1 was the only core from the three 

reservoirs that showed an increasing trend with respect 

to nitrogen.

The median phosphorus concentration was 

616 mg/kg in core samples from Kirwin Reservoir, 

compared to 562 and 652 mg/kg in samples from 

Webster Reservoir and Waconda Lake, respectively. 

The only reservoir with core samples showing an 

increasing trend in phosphorus concentration 

was Kirwin.

The median TOC concentration in core samples 

from Kirwin Reservoir was 11,600 mg/kg, compared 

to 12,300 mg/kg in samples from Webster Reservoir 

and 16,700 mg/kg in samples from Waconda Lake. 

None of the core samples from the three reservoirs 

showed an increasing trend for TOC.

Bottom-Sediment Volume and Mass in 

Webster Reservoir

Additional sediment cores were collected from 

seven sites (WEB 3 through WEB 11, fig. 25) in Webster Reservoir to estimate the mass of bottom sediment. Of the three reservoirs in the Solomon River 

Basin, complete bathymetric data were available only 

for Webster Reservoir. An extensive sedimentation 

survey of Webster Reservoir was completed by the 

Bureau in 1996. This survey showed very little

sediment deposition in Webster Reservoir given the 

size of its drainage area (Ferrari, 1997). Previous surveys by the Bureau in 1968 and 1979 verify the small 

accumulation of sediment. In addition, during this 

study, several attempts to collect sediment outside the 

original channel bed failed because there was no sediment or there was too little sediment for analysis, confirming findings of previous bathymetric surveys. The 

1996 survey estimated that a total of 1,267 acre-ft of 

sediment has accumulated since dam closure in 

May 1956; approximately 81 percent of the sediment 

was deposited in the original channel bed (Ferrari, 

1997). As with previous surveys, the 1996 survey 

showed very little sediment deposition outside of the 

original channel bed, except for some accumulation 

near the north bank due to bank erosion.

The sediment volume determined by the Bureau's 

1996 sedimentation survey of Webster Reservoir was 

used to estimate the 1998 volume and mass of sediment for the reservoir. The Bureau's estimated annual 

loss in storage capacity was 31.7 acre-ft per year; 

therefore 31.7 acre-ft was added to the 1996 sediment 

volume to estimate 1997 volume, and 31.7 acre-ft was 

added to the 1997 volume for 1998. The final estimated sediment accumulation in the reservoir for 1998 

was 1,330 acre-ft.

Bulk density, the weight per unit volume of the 

oven-dried bottom sediment, was calculated for all 

sites in Webster Reservoir using methods described by 

Guy (1969). Bulk density generally was higher for the 

out-of-channel cores; the mean out-of-channel bulk 

density was 91.0 Ib/ft (samples containing original 

material were not included), and the mean in-channel 

bulk density was 48.9 Ib/ft3 . Because of the differences in bulk density, mass was calculated separately 

for in-channel and out-of-channel components. On the 

basis of the Bureau's estimate that 81 percent of sediment accumulation was in the original channel bed, 

1,080 acre-ft of sediment was multiplied by the mean 

bulk density of all in-channel samples (sites WEB 1-5, 

fig. 2B) to estimate the in-channel sediment mass. 

Similarly, the remaining 253 acre-ft of sediment accumulation was multiplied by the mean out-of-channel 

bulk density to estimate the out-of-channel sediment 

mass. These two components were summed to arrive 

at the total mass of sediment accumulation in Webster 

Reservoir since dam closure in 1956 of 3,300 million 

Ib. It is important to recognize that the core-shortening 

phenomenon may affect bulk-density calculations and 

thus the calculation for total mass. The mass calcula26 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
tion presented here has not been corrected for core 

shortening.

Mean annual sediment deposition was calculated 

by dividing the total mass of sediment accumulation 

by 42 (the number of years since dam closure). Mean 

annual sediment deposition was calculated as 

78,600,000 Ib/yr. This estimate does not reflect probable differences in sedimentation from year to year. In 

addition, because mean bulk density was used in the 

calculation, mean annual sediment deposition may be 

understated if the core-shortening phenomenon discussed previously was due to a loss of sediment in 

the core.

Selenium, Arsenic, and Strontium Loads 

in Webster Reservoir

To estimate the loads of selenium, arsenic, and 

strontium transported into Webster Reservoir, the inand out-of-channel components were calculated separately and then summed. The mean concentration for 

all in-channel cores was multiplied by in-channel mass 

to provide an estimate of the total mass in the original 

channel bed. Similarly, the mean out-of-channel concentration was multiplied by the out-of-channel mass. 

Sample intervals that contained original channel-bed 

material or land-surface material were not included in 

the calculations. Mean annual loads of selenium, 

arsenic, and strontium transported into Webster Reservoir and accumulated as bottom sediment were estimated by dividing the total mass of each constituent 

by 42 years.

The average in-channel selenium concentration 

was 1.5 mg/kg. On the basis of this concentration, the 

estimated total in-channel selenium mass was 3,450 Ib 

for May 1998. The average out-of-channel concentration of selenium was 0.6 mg/kg. The estimated out-ofchannel mass of selenium was 601 Ib. The average 

selenium concentration is larger for the in-channel 

component. Selenium is strongly sorbed to finegrained particle sizes, such as are present in the original channel. The original channel bed receives finegrained sediment from channel erosion, irrigation runoff, and runoff due to floods. The out-of-channel component is mainly the recipient of sediment from bank 

erosion, which would naturally contain larger grain 

sizes and thus contain smaller selenium concentrations. The total estimated mass of selenium in Webster 

Reservoir was 4,050 Ib in May 1998. The annual load 

of selenium was estimated as 96.4 Ib.

The average arsenic concentration for in-channel 

coring sites was 9.3 mg/kg; therefore, the estimated 

total in-channel mass of arsenic was 21,400 Ib for May 

1998. The average out-of-channel arsenic concentration was 4.6 mg/kg; therefore, the estimated total outof-channel mass of arsenic was 4,610 Ib for May 1998. 

The average in-channel arsenic concentration is more 

than twice the average out-of-channel arsenic concentration. This probably is due to the larger percentage of 

sand in the out-of-channel cores and the fact that 

arsenic is associated with smaller grain sizes that 

occur in the channel. This stresses the importance of 

calculating in- and out-of-channel components separately and determining the percentage of silt and clay. 

The total mass of arsenic in Webster Reservoir was 

estimated as 26,000 Ib. The annual load of arsenic was 

calculated as 619 Ib.

The average in-channel strontium concentration 

from Webster Reservoir was 159 mg/kg. Therefore, 

the estimated total in-channel mass of strontium was 

366,000 Ib for May 1998. The average out-of-channel 

strontium concentration was 186 mg/kg. On the basis 

of this concentration, the estimated total out-ofchannel mass of strontium in Webster Reservoir was 

186,000 Ib. The total estimated strontium mass in 

Webster Reservoir was 552,000 Ib. The annual load of 

strontium into the reservoir was estimated as 

13,100 Ib. Unlike selenium and arsenic, average strontium concentrations are larger outside of the original 

channel, indicating that strontium is not as strongly 

associated with the smaller grain sizes within the 

channel. The larger out-of-channel strontium concentrations may be due to replacement of calcium in common rock minerals associated with larger grain sizes

COMPARISON OF DEPOSITIONAL 

TRENDS TO IRRIGATION AND 

CONSTITUENT LOADS

The possible effect of irrigation on selenium, 

arsenic, and strontium concentrations in bottom sediment was assessed first by comparing the annual 

change in irrigated acres in Kirwin and Webster Irrigation Districts (fig. 9) to selenium, arsenic, and strontium concentration profiles in cores from Waconda 

Lake (figs. 6-8), which receives water from these 

Bureau-operated irrigation districts. The amount of 

land irrigated with water from Kirwin and Webster 

Irrigation Districts, which depend on available water 

supply, has not consistently increased through the

Comparison of Depositional Trends to Irrigation and Constituent Loads 27
1955

0 10,000 20,000 

Bureau of Reclamation irrigated 

acres upstream from Waconda Lake 

Figure 9. Irrigated acres in Kirwin and 

Webster Irrigation Districts, 1957-97.

years. The concentrations of selenium, arsenic, and 

strontium in reservoir bottom sediment, however, have 

increased since completion of Waconda Lake in 1967. 

Therefore, constituent concentrations in Waconda 

Lake bottom sediment cannot be explained entirely by 

Bureau irrigation.

To further assess the effect of Bureau irrigation, 

the mean concentrations of selenium, arsenic, and 

strontium in bottom sediment from Waconda Lake, 

which receives inflow from both Bureau- and nonBureau-irrigated areas, were compared to mean concentrations in bottom sediment from Kirwin and Webster Reservoirs, which do not receive inflow from 

Bureau-irrigated areas. When comparing bottomsediment constituent concentrations in Kirwin and 

Webster Reservoirs to Waconda Lake, it is important 

to consider the difference in geology between the reservoirs. The geology changes from primarily Quaternary and Tertiary strata upstream from Kirwin and 

Webster Reservoirs to primarily Cretaceous strata 

downstream from these two reservoirs (fig. 1). In addition, the only outcrop of Pierre Shale, a known source 

for selenium, in the Solomon River Basin is in a small 

area upstream from Webster Reservoir. Another 

important consideration in comparing bottom-sediment concentrations is the difference in the source of 

irrigation water, which is ground water upstream from 

Kirwin and Webster Reservoirs and surface water 

upstream from Waconda Lake.

The median selenium concentration in core samples from Waconda Lake is less than the median concentration in samples from Kirwin Reservoir and 

equal to the median concentration in samples from 

Webster Reservoir (table 7). The median arsenic and 

strontium concentrations in core samples from 

Waconda Lake are larger than the median arsenic and 

strontium concentrations in samples from Kirwin Reservoir and smaller than the median concentrations in 

samples from Webster Reservoir. Because constituent 

concentrations in bottom sediment from Waconda 

Lake are not generally larger or smaller than constituent concentrations in bottom sediment from Kirwin 

and Webster Reservoirs, Bureau irrigation, which 

occurs upstream from Waconda Lake, does not 

entirely explain increasing trends in selenium, arsenic, 

and strontium concentrations in bottom sediment from 

Waconda Lake.

The effect of total (Bureau and non-Bureau) irrigation on selenium, arsenic, and strontium concentrations was assessed by comparing background 

constituent concentrations (before 1963-64) to constituent concentrations after 1964 (post background) 

for Kirwin and Webster Reservoirs. Background concentrations for selenium, arsenic, and strontium were 

represented in bottom-sediment samples from Kirwin 

and Webster Reservoirs, which were constructed prior 

to the major period of irrigation development in the 

Solomon River Basin (early to mid-1960's). Background concentrations could not be calculated for

Waconda Lake because of its 1967 completion date. 

137Cs results indicated sample intervals from Kirwin

and Webster sediment cores that were deposited prior 

to 1963-64 and thus are representative of background conditions.

Mean post-background selenium, arsenic, and 

strontium concentrations in core samples from Kirwin 

and Webster Reservoirs were larger than background 

concentrations in those reservoirs (fig. 10A, 10#, and 

10C). Because there are no Bureau-irrigated acres 

upstream from Kirwin and Webster Reservoirs, 

Bureau irrigation is not affecting the concentrations of 

selenium, arsenic, and strontium in bottom sediment 

from these reservoirs. However, other irrigation (nonBureau) activities in the basin may be contributing to 

the trend to larger post-background constituent concentrations. Without sufficient historical irrigation data 

in the Solomon River Basin, this is difficult to verify.

Although selenium, arsenic, and strontium concentrations have increased in reservoir-bottom sedi28 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
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Background (prior to 1964) 

Post background

Kirwin Reservoir

Figure 1 1. Background and post-background mean annual streamflow into 

Kirwin Reservoir, Webster Reservoir, and Waconda Lake.

would be positively 

biased towards postbackground annual 

loads (given the fact 

that bulk density 

increases 

with depth).

Differences in 

constituent loads 

with time may be 

due to several factors, including 

changes in 

streamflow, precipita 

tion, land use, source 

and type of irrigation, and land-management practices. 

Background and

post-background mean annual streamflow was examined to determine how much of the difference in background and post-background loads were due to 

changes in streamflow (fig. 11). For Webster Reservoir, decreases in mean annual streamflow and selenium, arsenic, and strontium loads are in 

agreement. However, the relative difference in background compared to post-background constituent 

loads is greater than the difference in background 

compared to post-background mean annual streamflow. Therefore, the larger constituent loads after 1964 

are not completely due to changes in streamflow. 

Although consitutent loads were not calculated for 

Kirwin Reservoir and Waconda Lake, these reservoirs 

also had larger mean annual streamflows prior to 1964, 

and it is reasonable to assume that constituent loads 

also would be larger prior to 1964.

SUMMARY

The Solomon River Basin extends across parts of 

17 counties in north-central Kansas and drains about

r\

6,840 mi of mainly agricultural land. Sediment quality of the three reservoirs in the basin is a concern 

because sediment quality reflects the quality of the 

overlying water. The Solomon River Basin is underlain by marine strata, and irrigation return flow in 

areas underlain by these rocks may contain concentrations of selenium that, when introduced into a lake, 

reservoir, or wetland area, may bioaccumulate to levels toxic to aquatic organisms, predatory species, or

Webster Reservoir Waconda Lake

potentially could 

affect human health 

through consumption of contaminated 

organisms.

Public Law 

99-294, National 

Environmental Policy Act (NEPA) of 

1986, requires that 

the Bureau of Reclamation (Bureau), 

U.S. Department of 

the Interior, investigate soil characteristics that may result 

in toxic or hazardous irrigation return 

flows. The Bureau,

in response, has begun a Resource Management 

Assessment (RMA) of the Solomon River Basin to 

provide the necessary data for NEPA compliance 

before renewal of long-term water-service contracts 

with irrigation districts in the basin.

The study described in this report was begun in the 

spring of 1998 by the U.S. Geological Survey in cooperation with the Bureau to determine if irrigation by 

the Bureau was increasing selenium concentrations in 

the basin. The primary purpose of this report was to 

document baseline conditions and trends in deposition 

of selenium and other constituents in three reservoirs 

of the Solomon River Basin.

Approximately 3 to 4 percent of the Solomon 

River Basin is irrigated. Water for irrigation in the 

basin comes primarily from ground water upstream 

from Kirwin and Webster Reservoirs, and primarily 

from surface water downstream from Kirwin and 

Webster Reservoirs. On the basis of 1995 irrigation 

data, approximately 48 percent of the total irrigated 

acres downstream from Kirwin, Webster, and 

Waconda are supplied water from Bureau-operated 

irrigation districts. However, no Bureau irrigation 

water is used upstream from Kirwin and Webster Reservoirs, making Bureau-irrigated acres only 12.1 percent of the total number of irrigated acres in the 

Solomon River Basin.

Reservoir bottom-sediment cores collected during 

this study were analyzed for selected physical properties, total recoverable metals, nutrients, 137Cs, and 

total organic carbon. The cores collected from within

30 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
the original river channel and near the dam of each reservoir generally had a percentage of silt and clay of 

more than 99 percent. Bulk-density values were generally larger in the deeper samples from the cores than in 

the shallower samples. Percentage of moisture was 

generally larger in the shallower samples than in the 

deeper samples from the cores. Cs, a by-product of 

nuclear weapons testing, was used to help date the 

cores and to determine if the sediment had been disturbed. Kirwin and Webster Reservoirs were built 

before the 1963-64 peak in atmospheric 137Cs concentrations, making it possible to assign a 1963-64 

date to the cores in these two reservoirs. The 137Cs 

concentration following the peak shows a smooth 

decline in concentration for all cores, which would 

indicate that the sediment has been relatively undisturbed by biological activity, inflows or outflows, 

human activity, or wind-induced currents.

Spearman's rho and Kendall's tau were calculated 

to determine if there were significant increasing trends 

in sediment constituent concentrations for the cores 

collected near the dam of each reservoir. Of the total 

recoverable metals analyzed in core samples from the 

three reservoirs, only three metals (selenium, arsenic, 

and strontium) showed an increasing trend in samples 

from at least two of the three reservoirs. None of the 

samples from reservoir-bottom sediment had increasing trends of nitrogen, phosphorus, or total organic 

carbon, except for the increase in phosphorus in cores 

from Kirwin Reservoir.

Additional samples were collected from Webster 

Reservoir to determine bottom-sediment thickness, 

volume, and mass. Using the Bureau's 1996 sedimentation survey and information on the length of cores 

collected for this study, the estimated volume of sediment accumulated in Webster Reservoir was 

1,330 acre-ft. The total mass of sediment accumulation in Webster Reservoir since dam closure in 1956 

was calculated as 3,300 million Ib.

To further analyze the effect of selenium, arsenic, 

and strontium on reservoir-bottom sediment, total 

mass and annual loads of each constituent transported 

into Webster Reservoir were calculated. The total 

estimated mass of selenium in Webster Reservoir was 

4,050 Ib. This corresponds to an annual load of about 

96.4 Ib. The total estimated mass of arsenic in Webster 

Reservoir was 26,000 Ib. The annual load of arsenic 

was calculated as 619 Ib. The total estimated strontium 

mass in Webster Reservoir was estimated as

552,000 Ib, and the annual load transported into the 

reservoir was about 13,100 Ib.

The possible effect of irrigation on selenium, 

arsenic, and strontium concentrations was assessed in 

several ways. First, the annual change in irrigated 

acres in Kirwin and Webster Irrigation Districts was 

compared to selenium, arsenic, and strontium concentration profiles in cores from Waconda Lake which 

receives water from these Bureau-operated irrigation 

districts. There appears to be no relation. Next, the 

median concentrations of selenium, arsenic, and strontium in bottom sediment from Waconda Lake were 

compared to mean concentrations in bottom sediment 

from Kirwin and Webster Reservoirs. Concentrations 

were not significantly larger in Waconda Lake and 

thus increases in median selenium, arsenic, and strontium concentrations in reservoir-bottom sediment can 

not be totally explained by Bureau irrigation.

Finally, the effect of total (Bureau and nonBureau) irrigation on selenium, arsenic, and strontium 

concentrations was assessed by comparing background (before 1963-64) constituent concentrations to 

post-background (after 1964) constituent concentrations for sediment cores from Kirwin and Webster 

Reservoirs. Mean post-background selenium concentrations in cores from Kirwin and Webster Reservoirs 

were larger than background concentrations in cores 

from those reservoirs. The same is true of both arsenic 

and strontium concentrations. Because there are no 

Bureau-irrigated acres upstream from Kirwin and 

Webster Reservoirs, it is clear that Bureau irrigation is 

not affecting the concentrations of selenium, arsenic, 

and strontium in bottom sediments from these reservoirs. However, other irrigation activities in the basin 

may be causing these trends. Without sufficient historical irrigation data for the Solomon River Basin, this is 

difficult to verify.

Background and post-background annual loads 

were calculated for selenium, arsenic, and strontium in 

bottom sediment from Webster Reservoir. Background 

selenium, arsenic, and strontium annual loads were 

significantly larger than post-background loads. An 

examination of background and post-background 

mean annual streamflows indicated that streamflow 

was not the only factor affecting differences in constituent loads. Differences in constituent loads with time 

may be due to several other factors including changes 

in precipitation, land use, source and type of irrigation, 

and land-management practices.

Summary 31
REFERENCES

Benninger, L.K., Suayah, I.E., and Stanley, D.J., 1997,

Manzala lagoon, Nile delta, Egypt modern sediment 

accumulation based on radioactive tracers: Environmental Geology, v. 34, no. 2/3, p. 183-193.

Blomqvist, Sven, and Bostrom, Kurt, 1987, Improved sampling of soft bottom sediments by combined box and 

piston coring: Sedimentoiogy, v. 34, p. 715-719.

Bureau of Reclamation, 1984, Solomon River Basin water 

management study, Kansas: U.S. Department of the 

Interior, Special Report, April 1984, 88 p.

 1996, Plan of action for Solomon River Basin water 

service contract renewal: U.S. Department of the Interior, Great Plains Region, February 1996, 30 p.

Callender, Edward, and Robbins, J.A., 1993, Transport and 

accumulation of radionuclides and stable elements in a 

Missouri River reservoir: Water Resources Research, 

v. 29, no. 6, p. 1787-1804.

Emery, K.O., and Dietz, R.S., 1941, Gravity coring instrument and mechanics of sediment coring: Bulletin of 

the Geological Society of America, v. 52, 

p. 1685-1714.

Emery, K.O., and Hulsemann, J., 1964, Shortening of sediment cores collected in open barrel gravity corers: Sedimentoiogy, v. 3, p. 144-154.

Engberg, R.A., 1993, Effects of drainwater from irrigation 

projects on water quality, bottom sediment, and biota, 

in Ecotoxicology and environmental chemistry a global perspective, First SETAC World Congress, abstract 

book: Lisbon, Portugal, Society of Environmental Toxicology and Chemistry, p. 253-254.

Ferrari, R.L., 1997, Webster Reservoir 1996 sedimentation 

survey: Denver, Colorado, Bureau of Reclamation, 

24 p.

Guy, H.P., 1969, Laboratory theory and methods for sediment analysis: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 5, chap. Cl, 

58 p.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: Amsterdam, Elsevier Science Publishers, 522 p.

Hem, J.D., 1992, Study and interpretation of the chemical 

characteristics of natural water (3d ed.): U.S. Geological Survey Water-Supply Paper 2254, 263 p.

Hirsch, R.M., Helsel, D.R., Cohn, T.A., and Gilroy, E.J., 

1993, Statistical analysis of hydrologic data, in Maidment, D.R., ed., Handbook of hydrology: New York, 

McGraw-Hill, Inc., p. 17.1-17.55.

Holmes, C.W., 1998, Short-lived isotopic chronometers a 

means of measuring decadal sedimentary dynamics: 

U.S. Geological Survey Fact Sheet FS-073-98, 2 p.

Hongve, Dag, and Erlandsen, A.H., 1979, Shortening of 

surface sediment cores during sampling: Hydrobiologia, v. 65, no. 3, p. 283-287.

Juracek, K.E., 1997, Analysis of bottom sediment to estimate nonpoint-source phosphorus loads for 1981-96 in 

Hillsdale Lake, northeast Kansas: U.S. Geological Survey Water-Resources Investigations Report 97-4235, 

55 p.

Kansas Department of Agriculture and U.S. Department of 

Agriculture, 1997, Kansas farm facts: Topeka, Kansas, 

various pagination.

Lemly, D.A., and Smith, G.J., 1987, Aquatic cycling of 

selenium implications for fish and wildlife: U.S. Fish 

and Wildlife Service, Fish and Wildlife Leaflet 12, 

10 p.

Leonard, A.R., 1952, Geology and ground-water resources 

of the North Fork Solomon River in Mitchell, Osborne, 

Smith and Phillips Counties, Kansas: Kansas Geological Survey Bulletin 98, 150 p.

McNeal, J.M., and Balistrieri, L.S., 1989, Geochemistry and 

occurrence of selenium an overview, in Jacobs, L.W., 

ed., Selenium in agriculture and the environment: 

Madison, Wisconsin, American Society of Agronomy, 

Inc., and Soil Society of America, Inc., various 

pagination.

Moore, R.C., and Landes, K.K., 1937, Geologic map of 

Kansas: Kansas Geological Survey, scale 1:500,000, 

1 sheet.

Mueller, D.K., Deweese, L.R., Garner, A.J., and Spruill, 

T.B., 1991, Reconnaissance investigation of water 

quality, bottom sediment, and biota associated with 

irrigation drainage in the Middle Arkansas River 

Basin, Colorado and Kansas, 1988-89: U.S. Geological Survey Water-Resources Investigation 

Report 91-4060, 84 p.

National Oceanic and Atmospheric Administration, 1997, 

Climatological data annual summary Kansas 1997: 

Ashville, North Carolina, v. Ill, no. 13, 

unnumbered pages.

Pais, Istvan, and Jones, J.B., 1997, The handbook of trace 

elements: Boca Raton, Florida, St. Lucie Press, 223 p.

Pope, L.M., 1998, Watershed trend analysis and water-quality assessment using bottom-sediment cores from 

Cheney Reservoir, south-central Kansas: U.S. Geological Survey Water-Resources Investigations 

Report 98^227, 24 p.

Ramirez, P., Jr., and Armstrong, J.A., 1992, Selenium in 

aquatic birds inhabiting the Kendrick Reclamation 

Project, Wyoming apparent impacts from irrigation 

drainwater [abs.], in Society of Environmental Toxicology and Chemistry 13th Annual Meeting, Abstracts of 

the Technical Sessions: Cincinnati, Ohio, 1992, p. 1.

Ritchie, J.C., Cooper, C.M., and McHentry, J.R., 1986, Sediment accumulation rates in lakes and reservoirs in the 

Mississippi River Valley, in River sedimentation, volume 3: Oxford, University of Mississipi Press, 

p. 1357-1365.

32 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Ross, J.A., compiler, 1991, Geologic map of Kansas: Kansas Geological Survey Map Series M-23, 

scale 1:500,000, 1 sheet.

Roy, R., and O'Brien, T., 1992, Bioaccumulation of selenium in wetland biota associated with irrigation drainage, San Juan River Basin, New Mexico [abs.], in 

Society of Environmental Toxicology and Chemistry 

13th Annual Meeting, Abstracts of the Technical Sessions: Cincinnati, Ohio, 1992, p. 2.

Sharma, S., and Singh, R., 1983, Selenium in soil, plant, 

and animal systems: CRC Critical Reviews in Environmental Control, v. 13, no. 1, p. 23-50.

Skougstad, M.W., Fishman, M.J., Friedman, L.C., Erdmann, 

D.E., and Duncan, S.S., eds., 1979, Methods for determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 5, chap. Al, 

626 p.

Taylor, J.K., 1987, Quality assurance of chemical measurements: Chelsea, Michigan, Lewis Publishers, 328 p.

U.S. Environmental Protection Agency, 1997a, Test methods for evaluating solid waste, physical/chemical 

methods, integrated manual SW-846: Washington, 

D.C.,various pagination.

 1997b, The incidence and severity of sediment contamination in surface waters of the United States, volume 1 national sediment quality survey: U.S. 

Environmental Protection Agency 

Report 823-R-97-006, various pagination.

Van Metre, PC., Callender, Edward, and Fuller, C.C., 1997, 

Historical trends in organochlorine compounds in river 

basins identified using sediment cores from reservoirs: 

Environmental Science and Technology, v. 31, 

p. 2339-2344.

Van Metre, PC., Land, L.F., and Braun, C.L., 1996, Waterquality trends using sediment cores from White Rock 

Lake, Dallas, Texas: U.S. Geological Survey Fact 

Sheet FS-217-96, 4 p.

Wallbrink, P.J., Murray, A.S., and Olley, J.M., 1998, Determining sources and transit times of suspended sediment in the Murrumbidgee River, New South Wales, 

Australia, using fallout 137Cs and 2l °Pb: Water 

Resources Research, v. 34, no. 4, p. 879-887.

Weast, R.C., ed., 1972, Handbook of chemistry and physics 

(53d ed.): Cleveland, Ohio, The Chemical Rubber Co. 

Publ., various pagination.

References 33
34 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
SUPPLEMENTAL INFORMATION

Supplemental Information 35
36 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 9. Core length, estimated sediment thickness, and recovery percentage for multiple cores from sediment 

coring sites in Kirwin Reservoir, Webster Reservoir, and Waconda Lake, May 1998

[core length and sediment thickness have not been corrected for original material thickness or core shortening, ft, feet; --, not determined]

Coresample 

identification

Core length

(ft)

Estimated 

sediment 

thickness (ft)

Recovery 

percentage

Kirwin Reservoir bottom-sediment cores (fig. 2A )

KIR 1.1 7.0 10.8 65

KIR 1.2

KIR 1.3

KIR 1.4

KIR 2.1

KIR 2.2

KIR 2.3

KIR 2.4

6.4

8.0

7.9

3.2

4.3

5.3

4.7

9.5

11.3

11.3

6.9

7.4

7.4

7.4

68

71

70

46

57

71

64

Webster Reservoir bottom-sediment cores (fig. 2B)

WEB 1.1

WEB 1.2

WEB 1.3

WEB 2.1

WEB 2.2

WEB 2.3

WEB 2.4

7.0

7.1

7.0

7.2

6.9

7.3

7.3

9.5

9.7

9.7

11.0

9.7

12.0

12.0

74

73

72

65

71

61

61

Coresample 

identification

Core length 

(ft)

Estimated 

sediment 

thickness (ft)

Recovery 

percentage

Webster Reservoir bottom-sediment cores (fig. 2fi) Continued

WEB 7.1 1.8 1.0 180

WEB 7.2

WEB 8.1

WEB 8.2

WEB 8.3

WEB 9.1

WEB 9.2

WEB 9.3

WEB 10.1

WEB 10.2

WEB 10.3

WEB 11.1

WEB 11.2

WEB 11.3

1.8

no sample

no sample

no sample

no sample

no sample

no sample

1.6

2.5

2.5

1.4

1.4

1.4

1.0

.1

0

0

--

--

--

4.8

4.8

4.8

3.4

3.1

3.3

Waconda Lake bottom-sediment cores (fig.

WEB 3.1

WEB 3.2

WEB 3.3

WEB 3.4

WEB 4.1

WEB 4.2

WEB 5.1

WEB 5.2

WEB 5.3

WEB 6.1

WEB 6.2

WEB 6.3

2.8

2.8

2.8

2.5

2.9

2.9

4.2

4.4

4.0

2.8

3.0

3.0

3.7

3.1

3.7

3.5

4.5

5.0

4.0

6.0

4.0

3.6

3.6

3.6

76

90

74

71

64

58

105

74

100

76

83

83

WAC 1.1

WAC 1.2

WAC 1.3

WAC 1.4

WAC 2.1

WAC 2.2

WAC 3.1

WAC 3.2

WAC 3.3

WAC 3.4

6.1

6.4

6.8

6.0

7.3

7.3

7.8

7.0

7.0

7.3

16.0

17.0

17.3

17.3

15.0

15.0

12.2

12.2

12.7

12.0

175

--

--

--

--

--

--

33

52

52

41

45

43

,2C)

38

38

39

35

48

48

64

57

55

61

Supplemental Information 37
Table 10. Results of analyses of selected physical properties for bottom-sediment cores collected in May 1998 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake

[ft, feet; lb/ft3 , pounds per cubic foot]

Core-sample Sample 

identification interval (ft)

Percentage of 

silt and clay

Percentage of Bulk density 

sand (lb/ft3)

Percentage of 

moisture

Kirwin Reservoir bottom-sediment cores (fig. 2A)

KIR 1.4

KIR2.1

6.5-7.9 (top)

5.9-6.5

5.5-5.9

4.7-5.5

4.2-4.7

3.9-4.2

3.5-3.9

2.7-3.5

2.2-2.7

0.92-2.2

0.46-0.92

0-0.46 (bottom)

2.7-3.2 (top)

2.5-2.7

2.2-2.5

1.9-2.2

1.5-1.9

1.3-1.5

1.0-1.3

0.5-1.0

0-0.5 (bottom)

98.9

97.7

98.8

99.7

98.8

99.7

100.0

99.9

99.8

100.0

100.0

99.9

99.4

99.8

98.9

98.9

99.6

99.7

99.9

99.9

99.3

1.1

2.3

1.2

.3

1.2

.3

0

.1

.2

0

0

.1

.6

.2

1.1

1.1

.4

.3

.1

.1

.7

27.5

38.1

38.2

34.7

44.2

41.7

42.6

45.4

44.2

44.5

43.5

42.7

30.9

37.0

34.1

33.0

35.8

40.2

35.4

42.8

50.4

65.5

60.0

58.5

61.4

54.2

56.1

54.3

52.0

52.6

46.9

49.6

53.0

63.1

57.3

58.8

60.3

59.3

54.5

57.6

54.1

46.8

Webster Reservoir bottom-sediment cores (fig. 20)

WEB 1.1

WEB 2.1

5.6-6.7 (top)

5.2-5.6

4.6-5.2

3.9-4.6

3.2-3.9

2.7-3.2

2.2-2.7

1.9-2.2

1.7-1.9

0.71-1.7

0.42-0.71

0.21-0.42 (bottom)

6.7-7.2 (top)

6.0-6.7

99.2

99.2

99.4

100.0

99.8

100.0

100.0

100.0

100.0

99.8

100.0

99.9

98.9

99.3

.8

.8

.6

0

.2

0

0

0

0

.2

0

.1

1.1

.7

27.3

31.8

35.1

40.9

32.0

35.4

31.7

34.2

33.9

38.0

35.3

48.6

21.1

29.4

63.7

61.7

57.1

57.0

61.9

57.0

58.0

56.1

57.8

54.3

56.3

46.6

72.9

66.6

38 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 10. Results of analyses of selected physical properties for bottom-sediment cores collected in May 1998 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake Continued

Core-sample 

identification

Sample 

interval (ft)

Percentage of 

silt and clay

Percentage of 

sand

Bulk density 

(Ib/ft3)

Percentage of 

moisture

Webster Reservoir bottom-sediment cores (fig. 2B) Continued

WEB 2.1

WEB 3.3

WEB 4.1

WEB 5.2

WEB 6.1

WEB 7.2

5.5-6.0

4.5-5.5

4.2-4.5

3.2-4.2

3.0-3.2

2.8-3.0

2.2-2.8

2.0-2.2

1.4-2.0

0-1 .4 (bottom)

1.8-2.8 (top)

1.1-1.8

0.8-1.1

0.3-0.8

0-0.3* (bottom)

2.7-2.9 (top)

2.0-2.7

1.2-2.0

0.6-1.2

0-0.6* (bottom)

3.5^.4 (top)

2.5-3.5

1.4-2.5

0.5-1.4

0-0.5 (bottom)

2.2-2.8 (top)

1.7-2.2

1.2-1.7

0.6-1.2

0-0.6 (bottom)

1.2-1. 8 (top)

0.8-1.2

0.3-0.8

0.2-0.3

0-0.2 (bottom)

99.8

99.8

100.0

99.9

100.0

99.9

100.0

100.0

100.0

100.0

99.2

99.8

83.9

41.8

4.0

10.2

3.9

1.0

1.9

33.0

99.5

88.7

100.0

100.0

100.0

6.9

4.6

5.8

21.3

21.9

98.6

98.4

95.0

26.9

93.5

0.2

.2

0

.1

0

.1

0

0

0

0

.8

.2

16.1

58.2

96.0

89.8

96.1

99.0

98.1

67.0

.5

11.3

0

0

0

93.1

95.4

94.2

78.7

78.1

1.4

1.6

5.0

73.1

6.5

25.6

35.0

34.1

37.5

37.5

36.0

45.4

35.1

39.8

41.1

25.1

33.7

48.0

101.9

115.0

92.7

120.2

141.8

129.2

95.2

75.9

63.5

51.7

43.7

40.6

133.3

125.2

121.6

110.6

97.1

46.0

60.7

63.8

82.1

72.8

65.6

61.6

60.9

60.4

55.9

63.8

53.6

61.8

55.3

56.2

67.8

62.1

50.8

20.6

13.9

10.2

10.6

15.3

14.3

19.6

44.3

45.6

53.8

55.8

56.5

15.0

15.1

16.1

19.0

17.8

42.9

33.7

33.6

28.2

26.9

WEB 10.1 1.0-1.6 (top) 32.4 67.6 93.1 23.7

Supplemental Information 39
Table 10. Results of analyses of selected physical properties for bottom-sediment cores collected in May 1998 

from Kirwin Reservoir, Webster Reservoir, and Waconda Lake Continued

Core-sample Sample 

identification interval (ft)

Percentage of 

silt and clay

Percentage of B"'k density 

sand (Ib/ft3)

Percentage of 

moisture

Webster Reservoir bottom-sediment cores (fig. 25) Continued

WEB 10.1

WEB 11.3

0.5-1.0

0-0.5 (bottom)

0.8- 1.4 (top)

0-0.8* (bottom)

46.8

57.1

70.7

89.4

53.2

42.9

29.3

10.6

94.8

96.1

76.3

75.7

23.7

22.6

26.9

27.7

Waconda Lake bottom-sediment cores (fig. 2C)

WAC 1.1

WAC 3.2

5.8-6.1 (top)

5.4-5.8

4.9-5.4

4.1-4.9

3.4-4.1

2.9-3.5

2.4-2.9

2.1-2.4

1.7-2.1

1.0-1.7

0.71-1.0

0-0.71 (bottom)

6.4-7.0 (top)

5.8-6.4

5.1-5.8

4.7-5.1

4.1-4.7

3.6-4.1

3.0-3.6

2.4-3.0

1.8-2.4

1.2-1.8

0.92-1.2

0-0.92 (bottom)

99.8

99.8

99.8

99.9

99.8

99.9

99.9

99.8

99.9

99.8

99.8

99.1

99.9

99.9

99.8

100.0

100.0

99.9

99.9

100.0

99.9

99.9

99.9

100.0

.2

.2

.2

.1

.2

.1

.1

.2

.1

.2

.2

.9

0.1

.1

.2

0

0

.1

.1

0

.1

.1

.1

0

27.3

29.8

27.1

26.8

29.3

21.1

29.7

29.9

32.0

41.4

42.5

47.0

21.6

25.0

29.2

27.8

22.0

30.0

33.6

28.9

22.0

35.9

30.1

43.7

62.4

62.5

63.4

65.5

62.7

64.3

65.8

60.7

59.9

53.6

52.9

45.1

73.1

68.6

67.0

67.5

67.7

66.9

63.5

67.2

64.5

59.3

57.3

46.3

*Sample intervals containing original channel-bed or soil-surface material.

40 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 11. Results of analyses of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, May 1998

[mg/kg, milligrams per kilogram; <, less than; , not determined]

Sample 

interval 

as measured 

from botCore- torn to 

sample top of 

identifi- core 

cation (feet)

Aluminum 

(mg/kg)

Arsenic 

(mg/kg)

Barium 

(mg/kg)

Beryllium 

(mg/kg)

Boron 

(mg/kg)

Cadmium 

(mg/kg)

Chromium 

(mg/kg)

Copper 

(mg/kg)

Iron 

(mg/kg)

Kirwin Reservoir bottom-sediment cores (fig. 2/4)

KIR1.3 7.54-8.00

7.08-7.54

5.83-7.08

5.33-5.83

4.67-5.33

4.21-4.67

3.92-4.21

3.33-3.92

2.71-3.33

2.12-2.71

1.50-2.12

0-1.50

KIR 2.2 3.75-4.25

3.54-3.75

2.67-3.54

2.37-2.67

2.00-2.37

1.83-2.00

1.46-1.83

1.21-1.46

1.00-1.21

0.67-1.00

0.33-0.67

0-0.33

33,200

32,200

34,100

33,500

36,900

50,300

29,700

31,700

32,600

31,400

31,800

13,500

35,300

18,500

43,400

50,900

38,600

35,800

39,600

47,700

43,000

54,300

49,900

34,900

7.3

5.7

8.4

7.8

8.1

8.5

7.5

5.4

5.8

6.9

8.3

4.6

7.4

5.1

8.1

7.9

8.2

8.7

10

8.7

9.4

9.3

8.2

5.4

294

279

284

292

283

335

305

313

307

301

327

255

283

216

326

333

294

287

311

336

310

337

362

264

<2.7

<2.2

<1.9

<2.5

<2.1

<2.6

<2.2

<2.4

2.0

<2.6

<2.4

<2.3

<2.5

<1.9

<2.7

<2.2

<2.3

<2.0

<2.3

2.4

<2.3

2.4

2.5

1.8

26

25

27

28

30

37

18

<19

19

<21

<19

<18

21

<15

28

31

27

26

27

35

32

36

33

24

<2.7

<2.2

<1.9

<2.4

<2.1

<2.6

<2.2

<2.4

<1.9

<2.6

<2.4

<2.3

<2.5

<1.9

<2.7

<2.2

<2.3

3.7

2.7

<2.1

<2.3

2.1

<1.8

<1.6

13

13

15

13

16

22

10

12

13

15

13

9

17

13

33

20

18

16

20

25

21

27

25

17

20

21

21

21

21

27

25

25

25

25

27

19

20

17

22

22

22

21

27

28

24

28

28

20

23,700

23,500

24,000

24,100

24,700

31,400

25,700

27,300

27,000

26,800

27,800

14,200

21,600

14,900

24,100

22,800

25,300

23,800

27,900

31,600

28,400

33,700

33,900

24,600

Webster Reservoir bottom-sediment cores (fig. 2B)

WEB 1.2 6.45-6.66

6.08-6.45

5.08-6.08

4.87-5.08

4.58-4.87

4.00-4.58

3.41-4.00

2.75-3.41

2.08-2.75

1.54-2.08

1.08-1.54

0-1.08

WEB 2.4 6.20-7.33

5.58-6.20

18,300

20,900

28,900

41,100

44,500

49,800

48,100

50,600

54,200

45,800

46,200

34,200

23,300

20,700

10.3

15.1

12.3

11.3

12.4

11.6

11.6

11.7

10.6

9.5

9.4

8.0

10

12.9

224

226

245

274

317

309

324

322

333

301

297

244

235

226

<2.6

<2.5

3.9

4.2

4.7

4.8

4.6

4.8

4.4

4.1

4.1

2.9

<3.1

<2.5

<20

<20

20

27

31

35

31

33

37

28

27

18

<24

<20

<2.6

<2.5

<2.4

<2.2

<2.5

<2.4

<2.2

<2.5

<2.0

<1.9

2.1

<1.5

<3.0

<2.5

<5

6

8

18

17

22

21

22

26

21

20

13

<6

<5

20

20

22

25

25

29

27

27

28

27

27

19

21

20

16,900

18,300

22,500

27,000

27,600

30,900

31,900

32,100

33,100

30,500

30,800

20,600

19,200

18,400

Supplemental Information 41
Table 11. Results of analyses 

Reservoir, Webster Reservoir,

of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

and Waconda Lake, May 1998 Continued

Coresample 

identification

WEB 2.4

WEB 3.3

WEB 4.1

WEB 5.2

WEB 6.1

WEB 7.2

Sample 

interval 

as measured 

from bottom to 

top of 

core 

(feet)

5.33-5.58

4.83-5.33

4.58-4.83

4.29-4.58

3.41-4.29

2.91-3.41

1.83-2.91

1.33-1.83

0.83-1.33

0-0.83

2.46-2.75

2.00-2.46

1.62-2.00

1.00-1.62

0-1.00

2.3-2.9

1.6-2.3

0.9-1.6

0.2-0.9

0-0.2

3.9^.4

3.0-3.9

1.9-3.0

0.9-1.9

0-0.9

2.2-2.8

1.6-2.2

1.1-1.6

0.6-1.1

0-0.6

1.6-1.8

1.5-1.6

1.0-1.5

0.6-1.0

0-0.6

Aluminum 

(mg/kg)

24,800

27,000

31,100

25,100

34,900

26,600

30,000

31,400

28,600

31,800

..

--

-

--

--

..

--

-

--

--

..

-

--

--

--

--

--

--

--

--

--

--

-.

Beryl- Cad- ChroArsenic Barium Hum Boron mium mium 

(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)

Webster Reservoir bottom-sediment cores (fig. 2B) Continued

12.2 258 <2.6 <21 <2.6 5

11.8 259 <2.6 <21 <2.6 7

10.9 272 <2.3 <19 <2.3 13

12.2 281 <2.2 <18 <2.3 7

9.4 281 <2.0 23 <2.0 14

11.2 295 <2.5 <20 <2.5 8

8.3 302 <2.1 18 <2.1 13

10.8 304 <2.3 21 <2.3 13

8.2 299 <2.1 <17 <2.1 11

9.0 289 <2.0 17 <1.9 13

9.2

10.2

9.7

2.4

.8

2.2

1.5

.9

1.1

2.9

8.2

9.9

10.2

10.2

8.8

1.9

1.3

1.4

2.6

1.9

7.5

9.3

9.2

8.5

2.7 -- -- -- -- .

Copper Iron 

(mg/kg) (mg/kg)

22 21,300

21 21,900

26 24,500

25 21,700

28 26,400

24 23,500

26 25,200

26 26,000

26 24,400

25 25,900

-

..

-

..

._

..

--

 ' 

-

..

--

_

..

..

--

-

-

-

WEB 10.1 0-1.6 4.1

WEB 11.3 0-1.4 - 3.0

42 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 11 . Results of analyses 

Reservoir, Webster Reservoir,

of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

and Waconda Lake, May 1998 Continued

Coresample 

identification

Sample 

interval 

as measured 

from bottom to

top of 

core 

(feet)

Aluminum 

(mg/kg)

Arsenic 

(mg/kg)

Barium 

(mg/kg)

Beryllium 

(mg/kg)

Boron 

(mg/kg)

Cadmium 

(mg/kg)

Chromium 

(mg/kg)

Copper 

(mg/kg)

Iron 

(mg/kg)

Waconda Lake bottom-sediment cores (fig. 2Q

WAC 1.3

WAC2.1

WAC 3.1

6.17-6.75

5.75-6.17

5.04-5.75

4.67-5.04

4.33^.67

3.83^.33

3.25-3.83

2.62-3.25

1.83-2.62

1.37-1.83

0.92-1.37

0-0.92

6.67-7.25

6.25-6.67

5.54-6.25

5.17-5.54

4.83-5.17

4.33-4.83

3.75-4.33

3.12-3.75

2.33-3.12

1.87-2.33

1.42-1.87

0-1.42

6.83-7.75

6.50-6.83

5.96-6.50

5.33-5.96

4.75-5.33

4.17-4.75

3.54-4.17

2.67-3.54

1.67-2.67

1.21-1.67

0.58-1.21

0-0.58

29,300

27,800

25,800

30,300

25,500

27,500

26,400

25,700

31,700

24,400

25,200

24,900

23,000

26,700

22,100

24,600

25,700

26,300

28,600

27,100

30,300

32,500

25,400

25,400

50,900

26,100

26,100

26,800

23,300

23,300

29,600

28,700

23,200

18,700

30,800

15,000

12.1

12.4

12.0

13.1

12.5

11.0

9.7

9.2

10.1

9.1

9.4

10.4

9.3

10.6

11.3

12.5

12.5

12.3

10.4

10.3

10.7

11.9

10.1

10.4

11.1

8.4

9.0

8.2

7.9

8.1

8.4

7.4

8.8

7.4

5.6

5.4

276

296

272

280

279

275

270

271

297

276

268

272

247

251

245

268

266

320

305

305

288

306

267

265

372

286

288

300

261

327

335

339

305

255

264

155

<3.5

<3.7

<3.3

<3.8

<2.8

<3.2

<3.0

<2.6

<2.9

<2.5

<2.5

<3.0

<3.0

<3.0

<3.5

<3.7

<2.8

<3.1

<2.7

<2.7

<2.6

<2.7

<2.3

<3.0

<5.1

<3.0

<3.6

<3.5

<3.5

<4.0

<3.1

<3.8

<2.6

<1.9

<1.7

<1.4

<28

47

<27

<30

<22

<26

<24

<21

<23

<20

20

<24

<24

<25

<28

<29

<23

27

24

28

22

<22

<18

<24

<41

26

<29

30

<28

37

34

42

26

19

16

<11

<3.5

<3.7

<3.3

<3.7

<2.8

<3.2

<3.0

<2.6

<2.9

<2.4

<2.4

<3.0

<3.0

<3.0

<3.5

<3.7

<2.8

<3.1

<2.8

<2.7

<2.6

<2.7

<2.3

<3.0

<5.1

<3.0

<3.6

<3.5

<3.5

<4.0

<3.1

<3.8

<2.6

<1.9

<1.7

<1.4

<7

10

<7

15

10

13

14

13

17

10

11

11

7

9

<7

9

9

10

11

11

12

13

9

11

<10

6

8

9

9

11

13

11

7

6

15

4

23

22

22

25

25

25

24

23

25

23

23

24

15

17

17

18

26

25

24

23

24

25

22

25

27

15

19

18

18

21

16

19

22

19

22

7

25,100

23,800

23,700

26,500

24,100

24,900

24,000

23,000

27,100

22,300

23,000

22,800

21,400

23,000

21,200

23,200

23,700

24,400

25,000

24,000

25,700

26,500

22,900

23,500

24,400

22,800

24,400

24,300

22,000

22,400

25,200

24,100

21,800

18,400

25,400

9,200

Supplemental Information 43
Table 11. Results of analyses of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample Magneidentifi- Lead slum 

cation (mg/kg) (mg/kg)

Manganese 

(mg/kg)

Mercury Nickel 

(mg/kg) (mg/kg)

Selenium 

(mg/kg)

Stron- Vanatium dium 

(mg/kg) (mg/kg)

Total Total 

nitro- phosZinc gen phorus 

(mg/kg) (mg/kg) (mg/kg)

Total 

organic 

carbon 

(mg/kg)

Kirwin Reservoir bottom-sediment cores (fig. 24)

KIR 1.3 20

19

21

19

14

23

22

26

23

16

16

21

KIR 2.2 16

 16

25

20

17

19

25

22

23

24

24

22

7,130

6,970

7,200

7,090

7,280

9,590

7,640

8,000

8,080

7,810

8,250

5,060

6,490

4,370

6,940

6,590

7,550

7,070

8,050

9,760

8,650

10,300

10,500

7,380

552

473

498

503

446

509

463

553

489

490

492

492

518

496

573

567

471

495

553

542

490

538

423

371

.<0.2 <11

<.2 <9

<.2 9

<.2 <10

<.2 9

<.2 12

<.2 13

<.2 11

<.2 13

<.2 15

<.2 12

<.2 10

<.2 12

<.2 <8

<.2 15

<.2 19

<.2 <9

<.2 11

<.2 12

<.2 24

<.2 14

<.2 14

<.2 14

<.2 12

2.2

2.0

2.0

1.0

1.1

2.2

1.6

1.9

.6

1.0

1.0

<.5

1.9

.5

1.6

.9

.6

1.3

1.6

.6

1.0

1.2

1.0

<.3

191

179

162

157

149

169

141

135

104

99

98

74

188

149

170

151

146

161

219

168

128

91

108

94

80

76

78

82

85

106

54

53

55

50

53

23

87

42

106

114

88

86

96

99

92

103

82

63

83

83

87

87

89

112

92

95

93

95

96

59

82

76

105

113

94

90

108

114

104

118

110

79

1,740

1,450

1,740

1,710

1,750

1,830

1,860

1,980

1,800

1,780

1,780

1,720

1,710

1,360

1,600

1,510

1,360

1,550

1,690

1,350

1,560

1,380

1,420

1,200

754

780

795

755

716

630

611

719

625

546

621

603

688

631

644

564

589

598

598

502

533

422

458

501

13,600

10,300

10,300

10,200

10,900

12.900

12,100

13,000

12,700

13,000

12,500

12,100

11,500

9,290

10,400

1 1 ,000

10,100

10,800

1 1 ,600

12,200

1 1 ,800

12,000

11,500

8,310

Webster Reservoir bottom-sediment cores (fig. 2B)

WEB 1.2 24

25

27

26

26

28

17

28

16

16

29

20

WEB 2.4 21

22

25

23

27

31

32

26

5,740

6,100

7,210

8,760

9,100

10,200

10,500

10,300

10,900

9,600

9,900

6,280

6,320

6,180

7,160

7,110

7,850

6,820

8,500

7,110

636

555

539

536

682

543

516

511

495

509

432

341

788

642

692

640

587

626

551

543

<.2 <10

<.2 <10

<.2 <10

<.2 16

<.2 13

<.2 19

<.2 17

<.2 19

<.2 30

<.2 17

<.2 16

<.2 11

<2 <12'

<.2 <10

<.2 <10

<.2 <10

<.2 13

<.2 14

<.2 19

<.2 <10

2.5

1.5

1.6

1.1

1.9

1.1

1.1

1.3

1.3

.7

1.6

.5

2.5

2.7

1.7

1.6

2.0

2.0

1.1

1.4

237

202

192

172

218

187

143

153

152

130

146

109

263

248

224

209

182

207

191

152

47

48

70

95

112

125

97

114

119

96

95

62

59

51

57

60

65

60

83

58

76

79

92

104

104

116

116

115

119

110

111

79

88

80

90

91

101

88

106

90

1,690

1,400

1,190

1,850

1,910

1,730

1,690

1,780

1,460

1,400

1,700

1,740

521

30.0

1,710

1,720

1,720

1,540

1,180

940

682

639

640

644

692

556

582

671

557

487

668

486

463

251

692

633

536

556

606

495

12,300

10,600

11,500

11,900

12,300

12,100

13,100

12,500

12,900

12,000

12,300

11,800

16,200

13,400

12,300

13,400

11,100

12,100

12,200

13,700

44 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
Table 11. Results of analyses of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample Magneidentifi- Lead sium 

cation (mg/kg) (mg/kg)

Manga- Mer- Selenese cury Nickel nium 

(mg/kg) (mg/kg) (mg/kg) (mg/kg)

Strontium 

(mg/kg)

Vanadium Zinc 

(mg/kg) (mg/kg)

Total 

nitrogen 

(mg/kg)

Total 

phosphorus 

(mg/kg)

Total 

organic 

carbon 

(mg/kg)

Webster Reservoir bottom-sediment cores (fig. 2B) Continued

WEB 2.4 29 8,190

28 7,930

28 7,660

22 8,040

WEB 3.3 -'-

..

..

..

--

WEB 4.1

..

..

-

-

WEB 5.2

..

..

..

--

WEB 6.1

-

..

..

--

WEB 7.2

-

-

..

--

WEB 10.1

WEB 11. 3

519 <0.2 15 0.9

509 <.2 18 1.2

505 <.2 17 1.1

519 <.2 16 .6

4.0

2.3

2.0

.6

.4

.7

.2

<.2

.2

.8

2.1

2.1

2.3

1.5

1.3

<.2

<.2

<.2

<.2

<.2

.3

3.9

.7

<3

<.3

.4

0.3

124

140

139

133

278.5

172.6

134.8

67.6

18.9

74.8

45.1

41.1

57.8

198.9

185.9

153.5

155.0

131.6

118.5

114.6

111.0

120.2

148.3

131.9

190.7

374.0

265.1

208.0

171.5

214.8

108.8

53 98

65 101

53 97

57 98

..

..

..

--

..

..

..

--

..

..

..

--

-.

..

..

..

--

..

..

--

--

..

1,020

1,710

1,450

1,600

--

--

--

--

..

-

--

--

--

..

--

--

--

--

..

--

--

--

--

-

-

--

--

--

467

567

520

463

98.9

352

403

219

69.4

159

67.5

54.8

57.9

91.1

314

116

58.7

63.3

118

97.8

107

609

166

246

112

351

384

337

<50

311

370

13,600

14,000

12,800

13,100

--

--

-

--

..

--

--

--

--

..

--

--

--

--

..

--

--

--

--

..

--

--

--

--

--

..

Waconda Lake bottom-sediment cores (fig. 2C)

WAC 1.3 <14 6,390

17 6,220

18 5,900

19 6,650

20 5,980

19 6,270

16 5,970

17 5,800

789 <.2 <14 1.7

736 <.2 <15 3.0

767 <.2 <13 1.1

841 <.2 <15 .9

987 <.2 13 .6

863 <.2 <13 <.6

749 <.2 <12 <.6

745 <.2 11 .8

197

199

216

157

168

164

134

122

66 119

65 137

60 103

67 104

58 94

64 133

59 95

57 101

2,180

2,520

2,340

2,070

1,580

1,700

2,040

2,050

719

771

744

701

568

558

641

690

17,300

18,100

16,700

16,400

16,100

16,000

17,400

18,200

Supplemental Information 45
Table 11 . Results of analyses of sediment-quality constituents in bottom-sediment cores collected from Kirwin 

Reservoir, Webster Reservoir, and Waconda Lake, May 1998 Continued

Coresample 

identifi- Lead 

cation (mg/kg)

Magnesium 

(mg/kg)

Manga- Mernese cury 

(mg/kg) (mg/kg)

Nickel 

(mg/kg)

Selenium 

(mg/kg)

Stron- Vanatium dium 

(mg/kg) (mg/kg)

Zinc 

(mg/kg)

Total 

nitrogen 

(mg/kg)

Total 

phosphorus 

(mg/kg)

Total 

organic 

carbon 

(mg/kg)

Waconda Lake bottom-sediment cores (fig. 2C) Continued

WAC1.3 19

17

18

17

WAC2.1 13

15

<14

22

16

24

18

18

21

19

19

17

WAC3.1 24

15

15

16

19

19

17

20

25

19

16

7

6,710

5,530

5,580

5,440

5,660

5,860

5,200

5,810

5,840

6,150

6,260

6,010

6,430

6,660

5,500

5,620

7,260

5,780

5,920

6,100

5,570

5,590

6,270

6,010

5,260

4,520

6,680

2,260

807 <0.2

812 <.2

767 <.2

639 <.2

704 <.2

670 <.2

861 <.2

777 <.2

903 <.2

905 <.2

774 <.2

745 <.2

791 <2

871 <.2

766 <.2

731 <.2

1,110 <.2

678 <.2

786 <.2

874 <.2

793 <.2

741 <.2

767 <.2

786 <.2

744 <.2

556 <.2

372 <.2

235 <.2

14

10

13

<12

<12

<12

<14

<15

12

14

15

16

18

15

15

15

<21

<12

<14

<14

<14

<16

<12

<15

<10

<8

13

6

0.8

.9

.6

.8

2.3

2.0

1.2

1.2

1.2

1.1

.8

.9

.9

1.3

1.4

.6

3.1

3.4

2.9

3.2

1.6

1.4

1.9

1.1

2.3

.7

<.4

.3

139

145

147

68

195

192

186

166

172

169

163

139

151

169

141

134

336

93

150

162

84

99

142

171

157

119

102

93

69

57

57

62

54

62

49

54

57

58

62

58

64

73

58

56

64

61

59

60

54

52

64

66

52

45

51

22

110

112

125

91

76

82

84

107

91

109

102

101

100

124

98

128

108

92

96

98

80

111

117

131

125

85

88

35

2,210

1,720

2,370

2,180

2,280

2,020

3,210

2,160

2,380

,780

,190

,540

,460

,880

2,050

1,890

2,630

2,550

2,220

2,180

2,100

2,150

1,610

1,760

1,800

1,910

1,620

704

658

618

785

710

451

281

843

646

740

589

506

621

475

589

600

680

885

904

812

111

726

673

483

544

565

661

533

526

19,600

18,000

18,400

16,500

16,600

14,900

15,900

14,800

17,600

16,700

19,100

17,800

17,600

17,200

19,600

19,400

16,100

13,700

15,700

14,800

14,800

16,100

16,000

17,900

19,900

17,300

10,300

3,440

46 Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon River Basin, North-Central Kansas
V. G. Christensen DEPOSITION OF SELENIUM AND OTHER CONSTITUENTS IN RESERVOIR BOTTOM SEDIMENT 

OF THE SOLOMON RIVER BASIN, NORTH-CENTRAL KANSAS USGS/WRIR 99-4230

©