U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008–5014

Prepared in cooperation with the 

JOHNSON COUNTY STORMWATER MANAGEMENT PROGRAM

Estimation of Constituent Concentrations, Loads, and 

Yields in Streams of Johnson County, Northeast Kansas, 

Using Continuous Water-Quality Monitoring and 

Regression Models, October 2002 through December 2006
Front cover. Blue River at Kenneth Road, June 2007 (photograph taken by Ryan Smith, U.S. Geological Survey, Lawrence Kansas).

Back cover. (Top) Blue River at Kenneth Road, May 2007 (photograph taken by Teresa Rasmussen, U.S. Geological Survey, Lawrence, Kansas); 

(Bottom) Indian Creek at State Line Road, March 2004 (photograph taken by Jeff Barnard, U.S. Geological Survey, Lawrence, Kansas).
Estimation of Constituent Concentrations, 

Loads, and Yields in Streams of Johnson 

County, Northeast Kansas, Using 

Continuous Water-Quality Monitoring and 

Regression Models, October 2002 through 

December 2006

By Teresa J. Rasmussen, Casey J. Lee, and Andrew C. Ziegler

Prepared in cooperation with the Johnson County 

Stormwater Management Program

Scientific Investigations Report 2008–5014

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

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

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Rasmussen, T.J., Lee, C.J., and Ziegler, A.C., 2008, Estimation of constituent concentrations, loads, and yields in 

streams of Johnson County, northeast Kansas, using continuous water-quality monitoring and regression models, 

October 2002 through December 2006: U.S. Geological Survey Scientific Investigations Report 2008–5014, 103 p. 
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Description of Study Area ...................................................................................................................5

Previous Studies ...................................................................................................................................6

Methods...........................................................................................................................................................7

Data Collection and Analysis..............................................................................................................7

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

Estimation of Constituent Concentrations, Densities, Loads, and Yields ..................................17

Duration Curves...................................................................................................................................17

Results of Continuous In-Stream Measurements ..................................................................................17

Streamflow...........................................................................................................................................17

Specific Conductance........................................................................................................................18

pH. ..................................................................................................................................................19

Water Temperature ............................................................................................................................21

Turbidity ................................................................................................................................................21

Dissolved Oxygen................................................................................................................................21

Variability in Streamflow and Water-Quality Measurements......................................................24

Relation Between Streamflow and Turbidity..................................................................................24

Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields...........................26

Regression Models.............................................................................................................................26

Regression-Estimated Constituents ................................................................................................39

Suspended Sediment and Total Suspended Solids..............................................................39

Dissolved Solids, Chloride, and Other Major Ions................................................................60

Fecal-Indicator Bacteria ..........................................................................................................70

Results of Selected Discrete-Sample Analysis ......................................................................................74

Nutrients...............................................................................................................................................74

Pesticides.............................................................................................................................................78

Watershed Characteristics Affecting Water Quality in Johnson County Streams...........................81

Summary and Conclusions.........................................................................................................................91

References Cited..........................................................................................................................................94

Appendix .......................................................................................................................................................99

Figures

1. Maps showing location of monitoring sites, watershed boundaries, and land use, 

Johnson County, northeast Kansas...........................................................................................3

2. Photographs of Kill Creek at 95th Street, one of five continuous water-quality 

monitoring sites in Johnson County, Kansas, and monitor used to measure continuous, in-stream specific conductance, pH, water temperature, turbidity, and dissolved 

oxygen ............................................................................................................................................7
iv

3–11. Graphs showing:

3. Comparison between suspended-sediment concentrations in samples collected using 

manual flow-weighted sampling methods and automated samplers at five monitoring 

sites in Johnson County, Kansas, 2003–06 ...............................................................................8

4. Duration curves for measured streamflow at five monitoring sites in Johnson County, 

Kansas, March 2004 through December 2006 .......................................................................18

5. Duration curves for measured specific conductance at five monitoring sites in Johnson County, Kansas, March 2004 through December 2006..................................................20

6. Duration curves for measured pH at five monitoring sites in Johnson County, Kansas, 

March 2004 through December 2006.......................................................................................20

7. Duration curves for measured water temperature at five monitoring sites in Johnson 

County, Kansas, March 2004 through December 2006.........................................................22

8. Duration curves for measured turbidity at five monitoring sites in Johnson County, 

Kansas, March 2004 through December 2006 .......................................................................22

9. Duration curves for (A) measured dissolved oxygen at five monitoring sites in 

Johnson County, Kansas, for March 2004 through December 2006 and (B) seasonal 

dissolved oxygen at the Indian Creek monitoring site for January 2005 through 

December 2006............................................................................................................................23

10. Variability in (A) streamflow, pH, water temperature, and dissolved oxygen and 

(B) specific conductance and turbidity at the Indian Creek monitoring site in Johnson 

County, Kansas, August 2005 ....................................................................................................25

11. Comparison of continuously measured streamflow and turbidity at the Cedar Creek 

monitoring site, Johnson County, Kansas, January 2005 through December 2006.........26

12. Diagram showing common streamflow and suspended-sediment hysteresis patterns, 

types, and sediment-source explanations .............................................................................27

13–34. Graphs showing:

13. Examples of hysteresis patterns in streamflow and turbidity data from selected monitoring sites in Johnson County, Kansas, 2004–05..................................................................28

14. Comparison of explanatory and response variables for selected water-quality constituent regression models for (A) suspended-sediment concentration, (B) chloride, and 

(C) Escherichia coli bacteria.....................................................................................................43

15. Duration curves for estimated suspended-sediment concentration at five water-quality 

monitoring sites in Johnson County, Kansas, March 2004–December 2006 ....................51

16. Estimated annual loads and yields for suspended sediment, chloride, and Escherichia 

coli bacteria at five water-quality monitoring sites in Johnson County, Kansas, 

2005–06 .........................................................................................................................................59

17. Duration curves for estimated suspended-sediment load at five water-quality monitoring sites in Johnson County, Kansas, January 2005–December 2006 ...............................60

18. Cumulative estimated suspended-sediment loads and frequency of exceedance at 

five water-quality monitoring sites in Johnson County, Kansas, January 2005–

December 2006............................................................................................................................66

19. Streamflow and cumulative suspended-sediment load at five water-quality monitoring 

sites in Johnson County, Kansas, 2005–06 .............................................................................67

20. Estimated suspended-sediment load during June 2005 at the Blue River monitoring 

site, Johnson County, Kansas...................................................................................................69

21. Duration curves for estimated chloride concentration at five water-quality monitoring 

sites in Johnson County, Kansas, March 2004–December 2006.........................................71
v

22. Frequency and probability of exceeding chloride criteria at the Indian Creek monitoring site, Johnson County, Kansas, January 2005–December 2006.....................................71

23. Cumulative estimated chloride loads and frequency of exceedance at five waterquality monitoring sites in Johnson County, Kansas, 2005–06............................................72

24. Seasonal chloride concentration duration curves at the Indian Creek monitoring site, 

Johnson County, Kansas, January 2005–December 2006....................................................72

25. Elevated chloride concentrations during snowmelt as a result of road-salt application at five water-quality monitoring sites in Johnson County, Kansas, January–

February 2005 ..............................................................................................................................73

26. Duration curves for estimated Escherichia coli bacteria at five water-quality monitoring sites in Johnson County, Kansas, March 2004–December 2006..................................74

27. Seasonal duration curves for estimated Escherichia coli bacteria density at the 

(A) Indian Creek and (B) Cedar Creek water-quality monitoring sites, January 2005–

December 2006............................................................................................................................75

28. Probability of exceeding Escherichia coli bacteria criteria at the (A) Blue River and 

(B) Indian Creek water-quality monitoring sites in Johnson County, Kansas, January 

2005–December 2006 .................................................................................................................76

29. Cumulative estimated Escherichia coli bacteria loads and frequency of exceedance 

at five water-quality monitoring sites in Johnson County, Kansas, January 2005–

December 2006............................................................................................................................77

30. Total annual estimated fecal coliform bacteria loads and loads originating from 

wastewater-treatment-facility discharges to Blue River and Indian Creek, Johnson 

County, Kansas, 2005–06............................................................................................................77

31. Concentrations of (A) total nitrogen and (B) nitrates as nitrogen in relation to streamflow at five water-quality monitoring sites in Johnson County, Kansas, October 

2002–January 2006 .....................................................................................................................80

32. Concentrations of total phosphorus in relation to streamflow at five water-quality 

monitoring sites in Johnson County, Kansas, October 2002–January 2006......................81

33. Annual estimated total nitrogen and total phosphorus loads originating from wastewater-treatment-facility discharges to Blue River and Indian Creek, Johnson County, 

Kansas, 2005–06..........................................................................................................................82

34. Constituent yields and impervious surface area at five water-quality monitoring sites in 

Johnson County, Kansas, 2005–06 ...........................................................................................90

Tables

1. Continuous in-stream monitoring sites, contributing drainage areas, estimates of urban 

and nonurban land-use percentages, and estimated number of septic systems per 

square mile of drainage area in Johnson County, northeast Kansas..................................4

2. Watersheds containing stream segments with 303(d) listings and total maximum daily 

loads (TMDLs) completed or being developed, Johnson County, northeast Kansas, 

2006 .................................................................................................................................................5

3. Water-quality constituents, units of measurement, laboratory reporting levels, 

and results of replicate stream sample and blank sample analysis for five waterquality monitoring sites in Johnson County, northeast Kansas, October 2002–

December 2006............................................................................................................................10
vi

4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and 

dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast 

Kansas, 2003–06..........................................................................................................................11

5. Mean daily streamflow, annual streamflow volume, and annual streamflow yield at five 

water-quality monitoring sites in Johnson County, northeast Kansas, 2004–06..............19

6. Average annual precipitation in five watersheds of Johnson County, northeast Kansas, 

2003–06 .........................................................................................................................................19

7. Relation between hourly streamflow and turbidity measurements at five water-quality 

monitoring sites in Johnson County, northeast Kansas, 2005–06.......................................26

8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson 

County, northeast Kansas, October 2002–January 2006......................................................29

9. Regression models and statistics for estimating concentrations of selected 

constituents using suspended-sediment concentration (SSC) in discrete samples 

from five water-quality monitoring sites in Johnson County, Kansas, October 2002–

January 2006................................................................................................................................40

10. Regression-estimated concentrations for selected water-quality constituents at five 

water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–

December 2006............................................................................................................................44

11. Estimated concentrations, loads, and yields for selected water-quality constituents at 

five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06 ......52

12. Regression-estimated loads for selected water-quality constituents at five waterquality monitoring sites in Johnson County, northeast Kansas, January 2005–

December 2006............................................................................................................................61

13. Percentage of annual suspended-sediment load that occurred during the single 

largest storm runoff for 2005 at five water-quality monitoring sites in Johnson County, 

northeast Kansas........................................................................................................................70

14. Results of analysis of nutrients in discrete samples collected at five continuous 

water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–

January 2006................................................................................................................................79

15. Results of analysis of pesticides in discrete samples collected at five continuous 

water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–

January 2006................................................................................................................................83
vii

Conversion Factors, Abbreviations, and Datum

Multiply By To obtain

acre-foot (acre-ft) 1,233 cubic meter (m3)

acre-foot per square mile per year 

[(acre-ft/mi2)/yr]

476.1 cubic meter per square kilometer per year 

[(m3/km2)/yr]

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

gallon (gal) 3.785 liter (L)

inch (in.) 2.54 centimeter (cm)

microgram per liter (μg/L) 1.0 parts per billion (ppb)

micron (μm) 0.00003937 inch (in.)

mile (m) 1.609 kilometer (km)

milligram per liter (mg/L) 1.0 parts per million (ppm)

milliliter (mL) 0.0338 ounce, fluid (oz)

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

pound (lb) 453.6 gram (g)

pound per acre (lb/acre) 1.121 kilogram per hectare (kg/ha)

square mile (mi2) 2.590 square kilometer (km2)

ton 0.9072 megagram (Mg)

ton per day (ton/d) 0.0105 kilogram per second (kg/s)

ton per square mile per year 

[(ton/mi2)/yr]

0.3503 tonne per square kilometer per year 

[(t/km2)/yr]

 

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

°F=(1.8×°C)+32.

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

°C=(°F-32)/1.8.

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

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25°C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Densities of fecal-indicator bacteria are given in colonies per 100 milliliters of water 

(col/100 mL).

Abstract

Johnson County is one of the most rapidly developing counties in Kansas. Population growth and expanding 

urban land use affect the quality of county streams, which are 

important for human and environmental health, water supply, 

recreation, and aesthetic value. This report describes estimates 

of streamflow and constituent concentrations, loads, and yields 

in relation to watershed characteristics in five Johnson County 

streams using continuous in-stream sensor measurements. 

Specific conductance, pH, water temperature, turbidity, and 

dissolved oxygen were monitored in five watersheds from 

October 2002 through December 2006. These continuous 

data were used in conjunction with discrete water samples 

to develop regression models for continuously estimating 

concentrations of other constituents. Continuous regressionbased concentrations were estimated for suspended sediment, 

total suspended solids, dissolved solids and selected major 

ions, nutrients (nitrogen and phosphorus species), and fecalindicator bacteria. Continuous daily, monthly, seasonal, and 

annual loads were calculated from concentration estimates and 

streamflow. The data are used to describe differences in concentrations, loads, and yields and to explain these differences 

relative to watershed characteristics.

Water quality at the five monitoring sites varied according to hydrologic conditions; contributing drainage area; land 

use (including degree of urbanization); relative contributions 

from point and nonpoint constituent sources; and human activity within each watershed. Dissolved oxygen (DO) concentrations were less than the Kansas aquatic-life-support criterion 

of 5.0 mg/L less than 10 percent of the time at all sites except 

Indian Creek, which had DO concentrations less than the criterion about 15 percent of the time. Concentrations of suspended 

sediment, chloride (winter only), indicator bacteria, and 

pesticides were substantially larger during periods of increased 

streamflow. Suspended-sediment concentration was nearly 

always largest at the Mill Creek site. The Mill Creek watershed is undergoing rapid development that likely contributed 

to larger sustained sediment concentrations. During most of 

the time, the smallest sediment concentrations occurred at the 

Indian Creek site, the most urban of the monitored sites, likely 

because most of the streamflow originates from wastewaterEstimation of Constituent Concentrations, Loads, and 

Yields in Streams of Johnson County, Northeast Kansas, 

Using Continuous Water-Quality Monitoring and 

Regression Models, October 2002 through December 2006

By Teresa J. Rasmussen, Casey J. Lee, and Andrew C. Ziegler

treatment facilities located just upstream from the monitoring site. However, estimated annual suspended-sediment 

load and yield were largest annually at the Indian Creek site 

because of substantial contributions during storm runoff. At 

least 90 percent of the total annual sediment load in 2005–06 

at all five monitoring sites occurred in less than 2 percent of 

the time, generally associated with large storm runoff. About 

50 percent of the 2005 sediment load at the Blue River site 

occurred during a single 3-day storm, the equivalent of less 

than 1 percent of the time. Suspended-sediment concentration 

is statistically related to other water-quality constituents, and 

these relations have potential implications for implementation 

of best management practices because, if sediment concentrations are decreased, concentrations of sediment-associated 

constituents such as suspended solids, some nutrients, and 

bacteria will also likely decrease. Chloride concentrations 

were largest at the Indian and Mill Creek sites, the two most 

urban stream sites which also are most affected by roadsalt runoff and wastewater-treatment-facility discharges. 

Two chloride runoff occurrences in January–February 2005 

accounted for 19 percent of the total chloride load in Indian 

Creek in 2005. Escherichia coli density at the Indian Creek 

site was nearly always largest of the five sites with a median 

density more than double that of any other site and 15 times 

the density at the Blue River site which is primarily nonurban. 

More than 97 percent of the fecal coliform bacteria load at 

the Indian Creek site and near the Blue River site originated 

from nonpoint sources in 2005 and 2006. In Johnson County, 

generally as impervious surface area increased, so did total 

annual yield for sediment, chloride, and indicator bacteria 

in 2005 and 2006. Total nitrogen discharged from the two 

Indian Creek wastewater-treatment facilities accounted for at 

least two-thirds of estimated total nitrogen load at the downstream Indian Creek monitoring site in 2005 and 2006. Total 

phosphorus load from the Indian Creek wastewater-treatment 

facilities was at least 90 percent of the total phosphorus load 

at the downstream monitoring site in 2005 and 2006. On the 

Blue River about 40 percent of the total nitrogen load in 2005 

and 70 percent of the total nitrogen load in 2006, when stormwater runoff was less, originated from wastewater-treatment 

discharge. One-fourth (in 2005) to one-half (in 2006) of the 
2 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

downstream total phosphorus load in the Blue River originated 

from WWTF discharges.

The results presented in this report may be used to better understand fluctuations of concentration and load during 

changing seasons and flow conditions and to assess waterquality conditions relative to total maximum daily load goals, 

National Pollutant Discharge Elimination System requirements, and water-quality standards. The information also 

will be useful for evaluating loading characteristics, such as 

range and variability, and for determining effectiveness of best 

management practices. The continuous streamflow data and 

estimated concentrations, densities, and loads are available at 

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

Introduction

Johnson County is one of the most rapidly developing 

counties in Kansas, with a population increase of about 90 percent in the last 25 years, from 270,269 in 1980 (University of 

Kansas, 2006) to an estimated 516,731 in 2006 (U.S. Census 

Bureau, 2007). Population growth and expanding urban land 

use affect the quality of county streams, which are important 

for human and environmental health, water supply, recreation, 

and aesthetic value.

Urbanization generally affects streams by altering hydrology, geomorphology, chemistry, and biology (Paul and Meyer, 

2001). Increases in impervious surface area from urbanization 

result in increased surface runoff, larger flood streamflows 

(Dunne and Leopold, 1978), and floods that peak more rapidly 

(Hirsch and others, 1990) but are shorter in duration (Seaburn, 

1969). Changes in channel depth and width occur in response 

to changes in streamflow and sediment supply (Dunne and 

Leopold, 1978). Stream-water chemistry is affected by 

increases in most water-quality constituents including nutrients such as ammonium and nitrate, major ions, suspended 

solids, metals, and hydrocarbons (Porcella and Sorenson, 

1980; U.S. Geological Survey, 1999), which can be attributed 

to nonpoint-source runoff, wastewater-treatment-facility discharges (Paul and Meyer, 2001), and other sources. Biological 

communities are affected by changes in habitat and stream 

hydrology and chemistry.

Effective implementation of total maximum daily loads 

(TMDLs) and the National Pollutant Discharge Elimination System (NPDES) program requires quantification and 

documentation of water-quality conditions and changes. 

Constituent concentrations and load information can be used 

to identify degraded stream segments, to evaluate compliance 

with water-quality standards, and to compare water-quality 

conditions over space and time. Required by the Federal Clean 

Water Act and established by States, TMDLs define the maximum quantity of a contaminant that a water body can receive 

and still meet water-quality criteria (Kansas Department of 

Health and Environment, 2004a). The U.S. Environmental 

Protection Agency’s (USEPA) NPDES Phase II Stormwater 

Program is designed to reduce effects of urban stormwater 

runoff on stream-water quality. Water-quality criteria for constituents discussed in this report are listed in Appendix 1.

Five watersheds in Johnson County (Blue River, Cedar 

Creek, Indian Creek, Kill Creek, and Mill Creek, fig. 1, 

table 1) contain stream segments that have been included by 

the Kansas Department of Health and Environment (KDHE) 

on the section 303(d) list (Kansas Department of Health and 

Environment, 2006a) for water-quality impairments (table 2). 

Kansas water-quality criteria for Escherichia coli (E. coli)

bacteria require stream sites to be classified and regulated 

according to designated use and accessibility (Appendix 1). 

Segments of the Blue River and Cedar, Kill, and Mill Creeks 

have been designated as primary contact recreation Class B, 

defined as being open to and accessible by the public with 

landowner permission. Designated uses for Indian Creek 

have not been determined by the State (Kansas Department of 

Health and Environment, 2005).

The NPDES program, which affects most municipalities 

in Johnson County, requires that best management practices 

(BMPs) be established to reduce runoff effects to urban 

streams (U.S. Environmental Protection Agency, 2005). In the 

early 1990s, Johnson County adopted a 1/10-cent sales tax to 

fund stormwater projects and created the Stormwater Management Advisory Council (SMAC). SMAC, composed of representatives from each of the county’s 20 cities, is an advisory 

group that makes recommendations to the county regarding 

the stormwater management program (Johnson County Stormwater Management Program, 2007).

In 2002, the U.S. Geological Survey (USGS), in cooperation with the Johnson County Stormwater Management 

Program and the financial oversight of SMAC, began an 

investigation to characterize the water-quality conditions of 

Johnson County streams. Initial study efforts described the 

effects of nonpoint and selected point contaminant sources on 

stream-water quality and the relation of contaminant sources 

to land use using analytical results from stream-water and 

streambed-sediment samples (Lee and others, 2005). A subsequent phase of the study characterized biological conditions of 

Johnson County streams (Poulton and others, 2007). The most 

recent part of the study investigated constituent concentrations, 

densities, loads, and yields using continuous in-stream sensor 

measurements.

Purpose and Scope

The purpose of this report is to describe methods and 

summarize results for providing continuous estimates of 

water-quality constituent concentrations, densities, loads, and 

yields in five Johnson County watersheds using continuous 

in-stream sensor measurements and regression models. Differences in water quality are described relative to watershed 

characteristics including hydrologic conditions, contributing drainage area, land use, point and nonpoint sources, and 

human activity. Specific conductance, pH, water temperature, 
Introduction 3

Figure 1. Location of monitoring sites, watershed boundaries, and land use, Johnson County, northeast Kansas.

5

35

35

435

435

56

56

69

10

7

7

169

50’

38°45’

39°

95° 94°55’

50’

45’ 94°40’

55’

MISSOURI

KANSAS

MIAMI COUNTY

DOUGLAS COUNTY

LEAVENWORTH COUNTY

WYANDOTTE COUNTY

 CASS COUNTY

JACKSON COUNTY

Kansas River

0 1 2 3 4 5 MILES

0 1 2 3 4 5 KILOMETERS

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

Albers Conic Equal-Area Projection,

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

Horizontal coordinate information is referenced to the

North American Datum of 1983 (NAD 83)

Land use from Johnson County Automated Information 

Mapping System (written commun., 2003)

Physiographic divisions from Schoewe (1949)

Mill Creek

watershed

Indian Creek

watershed

Brush Creek

watershed

Rock Creek

watershed

Turkey

Creek

watershed

Kill Creek

watershed

Cedar Creek

watershed

Blue River

watershed

Big Bull Creek

watershed

Little Bull Creek

watershed

Tomahawk

Creek

watershed

Captain

Creek

watershed

Dykes Branch

watershed

Kill Creek at 95th

Street (06892360)

Cedar Creek near

DeSoto (06892495)

Mill Creek at Johnson

Drive (06892513)

Indian Creek

at State Line

Road 

(06893390)

Indian Creek

at Overland

Park

(06893300)

Blue River at

Kenneth Road 

(06893100)

Blue River 

at Stanley

(06893080)

Captain Creek

Kill Creek

Big Bull Creek

Little Bull Creek

Mill Creek

Turkey Creek

Brush

Cree

Ro

k

ck Creek

Dykes

Branch

Indian Creek

Tomahawk Creek

Blue River

Lake Olathe

Cedar

Lake

Coffee Creek

Wolf Creek

Camp Branch

Osage Cuestas

Kansas City

metropolitan area Johnson County

Dissected Till Plains

Index map

KANSAS MISSOURI

EXPLANATION

Commercial

Industrial

Parks

Residential

Land use

Surface water

Nonurban land use

No data (government 

 property, public roads)

Watershed boundary

U.S. Geological Survey streamflow-gaging 

 station and number

Water-quality monitoring site

Municipal wastewater-treatment facility—

 Capacity more than 1 million gallons per day

Municipal wastewater-treatment facility—

 Capacity less than 1 million gallons per day
4 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 1. Continuous in-stream monitoring sites, contributing drainage areas, estimates of urban and nonurban land-use percentages, and estimated number of septic systems per square mile of drainage area in Johnson County, northeast Kansas. [Data from Johnson County Automated Information Mapping System, written commun., 2003; mi2, square miles] Continuous monitoring site (fig. 1) Station number Contribut- ing drain- age area (mi2

)

Percentage land use

Percentage 

impervious 

surface

Estimated 

number 

of septic 

systems per 

square mile of 

drainage area

Residential Commer- cial Indus- trial Rights-of- way Parks Surface water Unde- veloped1 (nonurban) No data2 Urban3

Blue River at Kenneth Road 06893100 65.7 15.1 2.5 1.0 0.6 1.6 2.2 69.3 7.7 23.0 3.0 36.5Cedar Creek near DeSoto 06892495 58.5 12.4 4.9 3.8 2.5 2.8 2.3 64.5 6.8 28.7 3.9 16.6Indian Creek at State Line Road 06893390 63.1 68.1 8.9 .3 1.9 2.2 .6 6.4 11.6 82.0 23.5 5.7Kill Creek at 95th Street 06892360 48.6 6.4 .9 1.3 .8 .5 1.9 61.7 26.5 11.8 2.9 14.8Mill Creek at Johnson Drive 06892513 58.8 26.7 11.1 2.8 3.4 3.4 1.9 37.8 12.9 49.3 12.2 24.4

1“Undeveloped” land use includes agricultural and vacant land.2“No data” land use includes untaxed land uses (such as government property and public roads).3“Urban” land use includes residential, commercial, industrial, rights-of-way, parks, and surface water.
Introduction 5

turbidity, and dissolved oxygen were monitored continuously 

in the five watersheds between October 2002 and December 

2006. The continuous information was used in conjunction 

with discrete water samples collected from October 2002 

through January 2006 to develop regression models for estimating selected constituent concentrations, loads, and yields. 

Continuous regression-based concentrations were estimated 

for suspended sediment, total suspended solids, dissolved 

solids, major ions, nutrients (nitrogen and phosphorus species), and fecal-indicator bacteria. Continuous daily, monthly, 

seasonal, and annual loads and yields were calculated using 

concentration estimates and streamflow. Relations between 

streamflow and turbidity are described to help infer sources of 

sediment in streams. In addition, results of discrete samples 

analyzed for pesticides are presented.

The results presented in this report may be used to better 

understand concentration and load fluctuations during changing seasonal and streamflow conditions and to assess waterquality conditions relative to TMDLs, NPDES requirements, 

and water-quality standards. With long-term operation, the 

information could be useful for evaluating loading characteristics such as range and variability of selected water-quality 

constituents, for describing the relation of loading characteristics to land use and basin characteristics, and for evaluating the 

effectiveness of implemented BMPs.

Description of Study Area

Johnson County, Kansas consists of 477 mi2 of surface 

area located in the western part of the Kansas City metropolitan area (U.S. Census Bureau, 2007). The five largest watersheds in Johnson County (fig. 1) comprise 73 percent of the 

total land area in the county and are the focus of this report. 

Designated uses for streams within the county include support 

of aquatic life, contact recreation, drinking-water supply, food 

procurement, ground-water recharge, irrigation, industrial use, 

and livestock watering (Kansas Department of Health and 

Environment, 2006a).

Physiographic regions of Johnson County include the 

Osage Cuestas in the central and southern parts of the county 

and the Dissected Till Plains along the northern part of the 

county (fig. 1) (Schoewe, 1949). The county is underlain by 

sedimentary rock characterized by alternating layers of limestone and shale and smaller amounts of fine-grained sandstone. Soils consist primarily of loess, glacial deposits, and 

residual from the weathering of bedrock (Plinsky and others, 

1975). Johnson County streams that flow north into the Kansas 

River such as Kill, Cedar, and Mill Creeks have steeper gradients than those flowing east such as Indian Creek and the Blue 

River (O’Connor, 1971).

The climate of Johnson County is classified as humid 

continental, characterized by variable weather patterns and 

large temperature ranges (Ritter, 2006). The mean annual temperature of the study area is about 55°F, with a mean monthly 

range from 28°F in January to 78°F in July (National Oceanic 

and Atmospheric Administration, 1966–98). Mean annual 

precipitation (1961–90) is about 40 in., with 68 percent of the 

rain occurring during the growing season from April through 

September (National Oceanic and Atmospheric Administration, 1966–98).

Population increases in Johnson County have resulted in 

increased urban and suburban land uses. From 1990 to 2004, 

land parcels dedicated to residential and commercial land 

use in Johnson County have increased more than 45 percent 

(K. Skridulis, Johnson County Appraiser’s Office, written 

commun., 2004). Figure 1 shows urban and nonurban land use 

for Johnson County in 2003 (S. Porter, Automated Information 

Mapping System, written commun., 2003). The northeastern 

part of the county including the Brush Creek, Dykes Branch, 

Table 2. Watersheds containing stream segments with 303(d) listings and total maximum daily loads (TMDLs) completed or being developed, 

Johnson County, northeast Kansas, 2006. 

[Data from Kansas Department of Health and Environment, 2006a; X, Section 303(d) listing and total maximum daily load developed; --, no total maximum 

daily load]

Watershed 

(fig. 1)

303(d) listing and TMDLs

Biology Dissolved 

oxygen

Chloride Chlordane1

Fecal 

coliform 

bacteria

Mercury Nitrates

Nutrients/ 

biological 

oxygen 

demand

Sediment 

impact on 

aquatic 

life3

Blue River -- X2 -- X X X1,2 -- X --

Cedar Creek -- -- -- -- X -- X -- --

Indian Creek -- -- -- -- X -- X2 -- --

Kill Creek -- -- -- X X -- -- -- --

Mill Creek X -- X -- X -- -- X X

1

Impairment identified by fish-tissue analysis.

2

TMDLs scheduled to be developed in 2006–08.

3

Impairment identified by biological monitoring.

 
6 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Indian Creek, Rock Creek, Tomahawk Creek, and Turkey 

Creek watersheds contain most of the urban development 

with more than 75 percent of the watershed areas devoted to 

residential, commercial, industrial, and rights-of-way land 

uses. More than 18 percent of these watersheds are overlain 

by impervious surface. New urban developments primarily are 

focused in the Blue River and Mill Creek watersheds (MidAmerica Regional Council, 2002).

Ten municipal wastewater-treatment facilities (WWTFs) 

are located within the monitored watersheds, seven of which 

have a design discharge capacity of more than 1 million 

gallons per day (Mgal/d) (fig. 1). The largest wastewater 

discharges occur in the Indian Creek watershed where two 

WWTFs with a combined design flow capacity of 22 Mgal/d 

discharge upstream from the monitoring site. The major 

WWTF in the Blue River watershed, which has a design flow 

capacity of 10.5 Mgal/d, discharges downstream from the 

monitoring site. The remaining three WWTFs in the monitored Cedar, Kill, and Mill Creek watersheds have design flow 

capacities ranging from 2.5 to 3.2 Mgal/d. Generally, WWTF 

effluent can affect water quality and biological communities of 

receiving streams by increasing oxygen-demanding substances 

such as organic matter and ammonia, which then reduce oxygen available to aquatic life and release excessive amounts of 

nutrients (such as carbon, nitrogen, and phosphorus), pathogens, and organic chemicals, altering stream-water temperature (U.S. Environmental Protection Agency, 2004b).

Previous Studies

Although a comprehensive study of Johnson County 

streams had not been conducted prior to 2002 when the current investigation began, studies of several streams and lakes 

within individual watersheds have been conducted. A study of 

Indian and Rock Creeks in 1981–82 (Mid-America Regional 

Council and F.X. Browne and Associates, Inc., 1983) found 

that commercial and industrial areas had increased nitrogen 

and metal concentrations, suspended-sediment concentrations were much larger during stormflow and likely originated from exposed soils and steep channel slopes, and some 

contaminants including phosphorus, manganese, and iron were 

associated with suspended sediment. A study of Lake Olathe 

in the Cedar Creek watershed (Mau and others, 2004) found 

nutrient yields consistent with mixed agricultural watersheds 

and atrazine concentrations that occasionally exceeded KDHE 

chronic aquatic-life criterion of 3.0 μg/L during spring and 

summer. A study of Big Bull and Little Bull Creeks found 

that during base flow the largest total nitrogen and phosphorus 

concentrations occurred downstream from wastewater discharges (Putnam, 1997).

Studies also have characterized water quality in the Blue 

River Basin in Kansas and Missouri. Indian Creek flows into 

the Blue River downstream from Johnson County and is, 

therefore, considered part of the Blue River Basin. Blevins 

(1986) recorded larger stormwater runoff per unit area for 

urban sites than for nonurban sites and smaller concentrations 

of suspended sediment, nutrients, and metals in concrete channels. During 1998–2000, the nearly continuous discharge of 

treated wastewater effluent was found to be a primary source 

of nutrients, wastewater compounds, and pharmaceutical compounds in the Blue River and Indian Creek (Wilkison and others, 2002). The same study found that overflow of combined 

storm and sanitary sewers triggered by stormflow contributed 

untreated wastewater into Brush Creek which feeds into the 

Blue River. In a followup study of the Blue River Basin, 

Indian Creek was found to contribute about 60 percent of total 

nitrogen and phosphorus loads to the Blue River in Missouri 

(Wilkison and others, 2005, 2006). In addition, bacteria in 

streams originated primarily from nonpoint sources during 

storm runoff (Wilkison and others, 2006).

Lee and others (2005) used water- and sediment-quality 

analysis from samples collected in multiple Johnson County 

watersheds from October 2002 through June 2004 to describe 

the effects of point and nonpoint contaminant sources on 

Johnson County streams. The study found that during baseflow conditions, discharge from wastewater-treatment facilities 

(WWTFs) comprised greater than 50 percent of total streamflow at the farthest downstream sampling sites in six of seven 

basins. Also during base-flow conditions, nutrients, organic 

wastewater-indicator compounds, and pharmaceutical compounds generally were found in the largest concentrations at 

sites at, or immediately downstream from, WWTF discharges. 

Nutrients, silver, and many wastewater-indicator and pharmaceutical compounds had the largest concentrations in streambed-sediment samples collected immediately downstream 

from WWTFs. Generally, sites upstream from WWTFs had 

significantly larger fecal-indicator bacteria densities than sites 

downstream during base-flow conditions, indicating WWTFs 

were not a major source of bacteria during base flow. The largest suspended-sediment concentrations and indicator-bacteria 

densities occurred during storm runoff. In addition, stormflow samples had the largest nutrient concentrations with the 

exception of samples collected immediately downstream from 

WWTFs. Trace elements, chlordane, total dichloro-diphenyltrichloroethane (DDT), polyaromatic hydrocarbons (PAHs), 

and some wastewater-indicator compounds had the largest 

concentrations in streambed sediment from watersheds with 

predominantly urban land use.

A recent biological assessment of Johnson County 

streams found that as urbanization increased, biological 

condition generally decreased, and stream conditions at the 

most urbanized sites were nonsupportive of aquatic life on the 

basis of State criteria (Poulton and others, 2007). In addition, 

upstream sites on the Blue River and Cedar and Kill Creeks 

were minimally affected by human disturbance, and Johnson County sites on Indian, Tomahawk, and Turkey Creeks 

and Missouri sites in downstream reaches of the Blue River 

and Brush Creek were most affected by human disturbance 

(Poulton and others, 2007).
Methods 7

Methods

Data Collection and Analysis

Continuous water-quality monitors (fig. 2) and streamflow-gaging stations were installed on five streams in Johnson 

County (fig. 1, table 1). Monitoring sites were located as far 

downstream as possible in the largest watersheds in the county 

and represented urban, urbanizing, and nonurban land uses. 

Streamflow was measured using methods presented in Buchanan and Somers (1969) and Oberg and others (2005). Each 

site was equipped with a water-quality monitor that provided 

continuous (every 5 or 15 minutes) in-stream measurements 

of specific conductance, pH, water temperature, turbidity, and 

dissolved oxygen (DO). Hourly values (values measured at 

1:00 am, 2:00 am, 3:00 am, and so forth) were used for data 

analysis and interpretation in this report. These data are available in real time on USGS Web pages (http:// ks.water.usgs.

gov/Kansas/rtqw/ and http://waterdata.usgs.gov/ks/nwis/). 

Monitor maintenance and data reporting followed standard 

procedures described in Wagner and others (2000, 2006). 

Two of the sites, Cedar Creek near DeSoto (station 06892495, 

fig. 1) and Mill Creek at Johnson Drive (station 06892513), 

were installed in October 2002, and three sites, Blue River 

at Kenneth Road (station 06893100), Indian Creek at State 

Line Road (station 06893390), and Kill Creek at 95th Street 

(station 06892360), were installed in March 2004. Results are 

presented for all sites through December 2006.

Continuous in-stream sensor data were compared to average cross-section data at the monitor location to verify that 

the continuous data were representative of conditions across 

the width of the stream. A total of 126 cross-section measurements were made with an independent water-quality monitor 

during various hydrologic conditions at the five monitoring 

sites. Each measurement consisted of about 10 readings within 

the cross-section. Relative percentage differences (RPDs) were 

calculated between the cross-section median for each constituent (specific conductance, pH, water temperature, turbidity, 

and DO) and the concurrent continuous-monitor reading. 

Median values were used because the mean was affected by 

extreme readings that occurred most often on the far right or 

left streambank where zero or low-velocity water was present 

(and therefore were not representative of flow conditions).

Monitor placement did not result in a consistent bias for 

any constituents measured at any of the water-quality cross 

sections. The median value of all 126 RPDs (which compared 

cross-section median to continuous-monitor reading) was less 

than 1 percent for each constituent at each station. Several 

continuous-monitor readings had more than a 10-percent difference between cross-section median values. Six turbidity 

values were more than 10-percent different from cross-section 

medians. All of these differences occurred at sites in which 

the monitor was installed on the right or left streambank rather 

than near the center of flow. The largest RPD for turbidity was 

38 percent and occurred at the Kill Creek site. One specific 

conductance value was more than 10 percent different (45 percent at Indian Creek), likely because of highway drainage 

pipes contributing road-salt affected runoff near the right bank 

where the monitor is located.

The quality of the continuous monitoring data during 

the study period generally was good according to guidelines 

described by Wagner and others (2006). Quality of in-stream 

sensor data was determined primarily by evaluating sensor 

readings during routine calibration verification procedures. 

Each monitor was serviced a minimum of 15 times annually 

Figure 2. (A) Kill Creek at 95th Street (station 06892360), one of five 

continuous water-quality monitoring sites in Johnson County, Kansas. 

The water-quality monitor is placed beneath the water surface next to 

the streambank. (B) Monitor used to measure continuous, in-stream 

specific conductance, pH, water temperature, turbidity, and dissolved 

oxygen. A fluorescence sensor is pictured, but fluorescence was not 

monitored continuously during this study.

(A) Kill Creek at 95th Street

(B) Continuous water-quality monitor

Location of water- quality monitor

Specific conductance

Temperature

Fluorescence

Turbidity Dissolved oxygen

pH
8 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

for routine cleaning and calibration purposes. If the majority 

of the cleaning and calibration measurements were less than 

10 percent different from the expected (cleaned and calibrated) 

value, the data quality was considered good. If the measurements differed by 10–15 percent, the data quality was considered fair. If the measurements differed by 15–30 percent, 

the data quality was considered poor. Data that differed by 

more than 30 percent were deleted from the dataset. Specific 

conductance, pH, and water temperature datasets were nearly 

always good. Turbidity data usually were good but occasionally fair. DO datasets were usually fair. The final data for 

all sensors were corrected to ensure accuracy as described 

by Wagner and others (2006). Annual datasets for in-stream 

sensor measurements were 90–100 percent complete except 

for DO at the Indian Creek site in 2006, which was 85 percent 

complete. More DO data were missing from the final dataset 

during 2006 because fouling of the sensor was more common 

during that time period, resulting in removal of more measurements that did not meet verification criteria described in 

the guidelines.

In addition to continuous monitoring, discrete water 

samples were manually collected from each site according to 

either the equal depth integrated (EDI) method or the equal 

width integrated (EWI) method described by Wilde and others (1999) or using automated samplers. Sample collection 

also followed methods described by Edwards and Glysson 

(1999) for collecting representative samples to be analyzed 

for suspended sediment and other water-quality constituents. 

Samples to be analyzed for dissolved constituents were filtered 

using 0.45 micron filters, and samples to be analyzed for total 

constituents were not filtered. Sample collection began when 

monitors were installed and continued through December 

2006. At each site, 18 to 28 samples were collected between 

October 1, 2002 and January 31, 2006 during various runoff 

conditions. About 90 percent of these samples were collected 

following width- and depth-integrated sampling methods, and 

the rest were collected using automated samplers. EDI and 

EWI sample collection, which results in integrated samples 

that are representative of the entire width and depth of the 

stream cross section, were generally the preferred sampling 

methods in this study. However, automated samplers also were 

used because storm runoff in small, urban basins often results 

in rapidly rising and falling streamflow peaks that can be difficult to capture with manual samples.

Because of the potential differences associated with sampling methods, 17 automated samples were collected as near in 

time as possible with integrated suspended-sediment samples 

to evaluate variability between the sampling methods (fig. 3). 

Results indicated that sediment samples collected using 

automated samplers differed from samples collected using 

integrated methods by an average of 28 percent (fig. 3). Differences occurred because automated samplers collect samples 

from a single point rather than a complete depth-integrated 

cross section and because varying pumping speed and stream 

Figure 3. Comparison between suspended-sediment concentrations in samples collected using manual 

flow-weighted sampling methods and automated samplers at five monitoring sites in Johnson County, 

Kansas, 2003–06.

y = 0.723x

Monitoring sites (fig. 1)

R2

 = 0.95

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Suspended-sediment concentration, in milligrams per liter,

using manual flow-weighted samples

Suspended-sediment concentration, in milligrams

per liter, using automated point samples

1:1 line

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Methods 9

velocity prevent the automated samplers from collecting 

isokinetic (equal flow) samples as is done with EDI and EWI 

methods. Other factors contributing to the difference include 

rapidly changing streamflow and sediment conditions (for 

example, an automated sample is collected from a fixed point 

usually within 15 minutes, and an EDI or EWI sample may 

require as much as an hour to collect) and lack of adequate 

lift from pumps to carry large amounts of suspended sediment 

from stream to samplers.

Samples were analyzed for nutrients, indicator bacteria, 

sediment, and other constituents. Data qualified by the analyzing laboratory as “estimated” (for example, bacteria in the 

“nonideal” count range as defined by the analytical method 

protocol) were treated the same as unqualified data. These 

discrete samples, including all samples regardless of collection method (EDI, EWI, automated sampler), were collected 

throughout the range of streamflow and sensor conditions 

recorded at each site. The discrete samples that were collected 

represented about 95 percent of the range in flow conditions 

for the site and represented rising, falling, peak, and base 

streamflow conditions.

Discrete quality-control samples, including blank and 

replicate samples, were collected and analyzed to assess variability among samples resulting from collection, processing, 

shipping, and laboratory procedures conducted at different 

sampling times (Wilde and others, 1999). Equipment blank 

samples were collected to measure a combination of the potential contamination from the equipment used in sample collection and environmental conditions in the laboratory. Rinse 

blank samples were collected to measure the effectiveness of 

equipment cleaning protocols and replicate samples were collected to evaluate laboratory and subsample bias and precision.

Water samples were analyzed at several laboratories. 

Major ions and nutrients were analyzed at the Johnson County 

Environmental Laboratory in Johnson County, Kansas, according to standard methods (American Public Health Association 

and others, 1995). Selected dissolved pesticides and replicate 

samples for major ions and nutrients were analyzed by the 

USGS National Water-Quality Laboratory (NWQL) in Denver, 

Colorado, according to methods presented in Fishman and 

Friedman (1989), Faires (1993), Fishman (1993), and Zaugg 

and others (1995). Suspended-sediment samples were analyzed by the USGS Sediment Laboratory in Iowa City, Iowa, 

according to methods presented in Guy (1969). Analysis of 

indicator bacteria (E. coli, fecal coliform, and enterococci) 

was done at the USGS laboratory in Lawrence, Kansas. The 

bacteria samples were processed within 6 hours of collection 

using membrane filtration methods described by Wilde and 

Radtke (1998). Although both USGS and Johnson County 

laboratories analyzed all three types of fecal indicator bacteria 

for most samples, results from USGS were used as the primary 

data source. Values reported by a laboratory as estimated 

occurred when data quantification deviated in any way from 

standard procedures. Tables containing additional constituents 

analyzed and laboratory reporting levels are provided in Lee 

and others (2005).

Results of blank and replicate sample analysis are 

included in table 3. The median RPD between replicate pairs 

was less than 10 percent for all constituents except some 

nutrient species and indicator bacterias. Analysis for most of 

the replicate samples involved analysis of the same sample 

set by the two different laboratories. For acid neutralizing 

capacity, dissolved solids, E. coli bacteria, and enterococci 

bacteria, comparison information applies to different laboratory methods used by the USGS and Johnson County laboratories. Both laboratories analyzed sulfate, silica, ammonia, and 

manganese for most samples because of method differences, 

resulting in more replicate pairs for these constituents than the 

other constituents except indicator bacteria (table 3). Pesticide compounds were not detected in blank samples. RPDs 

for pesticides when detectable concentrations were reported 

were less than 20 percent. Generally for all constituents, but 

especially for the nutrient species, larger RPDs occurred when 

values were near the reporting level. In addition, variability 

in indicator bacteria data may be caused by rapidly changing 

conditions during storm runoff making it difficult to collect 

samples with comparable bacteria densities.

Regression Models

Ordinary least squares (OLS) regression analysis was 

used to develop relations between the continuous sensor 

measurements, streamflow, time, and discretely sampled constituent concentrations (Helsel and Hirsch, 2002; Christensen 

and others, 2000). Discrete sample data used in regression 

analysis included EDI, EWI, and automated samples collected from October 2002 through January 2006. Site-specific 

regression models were developed using an overall modelbuilding approach (Helsel and Hirsch, 2002) that included 

plotting each possible explanatory (independent) variable 

against the response (dependent) variable and visually and 

statistically examining the residual plots for patterns. For 

each response variable, all continuously measured variables 

(streamflow, specific conductance, pH, water temperature, 

turbidity, and dissolved oxygen) were tested for significance. 

In addition, seasonal patterns in data were tested for significance by using sine and cosine terms as possible explanatory 

variables (Helsel and Hirsch, 2002). Explanatory and response 

variables (except time) were log transformed if necessary to 

normalize datasets to satisfy statistical assumptions, prior to 

developing the linear relation. Many data transformations and 

all possible regression equations were evaluated. Generally, 

if there were several acceptable models (F-test p-value less 

than 0.05), the one with the smallest prediction error sum of 

squares (PRESS) statistic was selected. The PRESS statistic is 

a measure of goodness of fit of a regression model (Helsel and 

Hirsch, 2002). Explanatory variables were included in a model 

only if there was a physical basis for their inclusion.

For statistical analysis, when concentrations were 

reported as less than the laboratory reporting level, they were 

assumed to be one-half the reporting level. Uncertainties 
10 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

associated with each model were evaluated on the basis of 

diagnostic statistics (R2, coefficient of determination; RMSE, 

root mean square error), patterns in residual plots, and the 

range and distribution of discrete (EDI, EWI, and automated) 

samples and continuous data.

Uncertainty for each estimate from regression models 

was calculated using 90-percent prediction intervals (Helsel 

and Hirsch, 2002). Probabilities of exceeding water-quality 

standards, recommended criteria, or guidelines of the State 

of Kansas and USEPA also were calculated (Rasmussen and 

Ziegler, 2003; Francy and Darner, 2006). Regression methods 

used in this study are described in greater detail in Cohn and 

others (1989), Hirsch and others (1993), Helsel and Hirsch 

(2002), and Rasmussen and Ziegler (2003). Duration (frequency of exceedance) curves were constructed to display 

and help characterize the frequency, duration, and magnitude 

of water-quality variability. When OLS regression is used to 

generate estimates for which probability statements are made, 

such as with duration curves and probability of exceeding 

criteria, values at the upper end likely are underestimated 

and values at the lower end may be overestimated (Helsel 

and Hirsch, 2002). The continuous concentration and load 

Table 3. Water-quality constituents, units of measurement, laboratory reporting levels, and results of replicate stream sample and blank sample 

analysis for five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002 through December 2006.

[RPD, relative percentage difference; mg/L, milligrams per liter; <, less than; μg/L, micrograms per liter; col/100 mL, colonies per 100 milliliters of water; 

--, not detected]

Constituent

Units of 

measurement

Laboratory 

reporting 

level

Replicate sample or 

method 

comparison results 

Blank sample results

Number of 

replicate 

pairs

 Median 

RPD1

Number 

of blank 

samples

Concentration 

range in blank 

samples

Acid neutralizing capacity mg/L 5 25 3.0 0 --

Dissolved solids mg/L 10 18 8.4 1 <10

Calcium, dissolved mg/L .02 19 9.6 3 0.08 – 0.1

Magnesium, dissolved mg/L .008 19 3.8 3 0.02 – <0.1

Sodium, dissolved mg/L .20 18 4.6 3 <0.1 – 0.6

Potassium, dissolved mg/L .16 18 4.7 3 <0.16 – <1.0

Sulfate, dissolved mg/L .18 83 6.7 5 <0.18 – <5

Chloride, dissolved mg/L .20 18 4.8 3 <0.2 – <10

Silica, dissolved mg/L .20 84 9.5 4 <0.1 – 1.68

Nitrogen nitrite, dissolved mg/L .002 18 50 3 <0.01 – <0.02

Nitrogen nitrite plus nitrate, dissolved mg/L .06 18 8.1 3 <0.05 – <0.06

Nitrogen, ammonia dissolved mg/L .02 87 30 4 <0.02 – <0.04

Nitrogen, ammonia plus organic, dissolved mg/L .10 19 24 3 <0.1 – <0.2

Nitrogen, ammonia plus organic, total mg/L .10 19 25 3 <0.1 – <0.2

Phosphorus, total mg/L .04 19 12 3 <0.01 – <0.04

Phosphorus, dissolved mg/L .04 19 8.6 3 <0.01 – <0.04

Phosphorus orthophosphate mg/L .006 18 6.0 3 <0.01 – <0.02

Manganese, dissolved μg/L .2 82 31 4 0.11 – <10

Escherichia coli (E. coli) bacteria col/100 mL 1 86 28 91 1 – 10 (7) 2

Fecal coliform bacteria col/100 mL 1 76 47 121 1 – 10 (8) 2

Enterococci bacteria col/100 mL 1 85 145 67 1 – 13 (9) 2

1 / 100, 2

A B RPD A B  +   =− ×       where A and B are concentrations in each replicate pair.

2

 Numbers indicate range in number of bacteria colonies. Number in parentheses ( ) indicates number of blank samples with bacteria colonies.
Methods 11

Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.[ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than]

Calendar year and 

monitoring site

Number 

of values

Percentage of 

hourly 

values 

missing

Sample 

standard 

deviation

Measurement at indicated frequency of exceedance

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum

Streamflow (ft3/s)

2003

6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Cedar Creek1 8,681 0.9 71.7 1.31 1.42 1.73 1.93 2.97 4.93 11.6 28.1 38.9 110 2,9506893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Mill Creek 8,760 0 168 1.64 1.91 2.82 3.51 4.59 7.34 15.3 32.4 60.1 431 6,020

2004

6893100 Blue River2 7,344 0 772 1.72 2.33 3.87 5.88 12.5 23.1 48.1 116 243 1,061 19,2006892495 Cedar Creek 8,656 1.5 275 2.40 4.15 4.93 6.61 11.0 18.7 31.2 58.6 101 461 6,1406893390 Indian Creek2 7,300 .6 497 13.6 18.7 22.8 25.3 28.1 37.4 63.0 139 301 1,461 11,6006892360 Kill Creek2 7,344 0 198 .88 1.19 1.91 2.45 4.79 9.61 18.0 47.9 114 516 4,6906892495 Mill Creek 8,784 0 298 4.35 6.62 8.13 9.72 13.2 19.0 30.9 66.5 143 651 9,700

2005

6893100 Blue River 8,760 0 336 .36 .43 .76 1.50 6.36 12.2 37.0 108 246 941 9,8406892495 Cedar Creek 8,649 1.3 205 2.75 3.25 5.69 7.14 9.55 15.5 34.7 77.8 174 952 4,3906893390 Indian Creek 8,711 .6 389 12.7 16.3 19.3 20.5 24.0 31.0 60.0 129 306 1,355 10,5006892360 Kill Creek 8,760 0 230 .81 .88 1.59 3.18 5.66 9.24 21.4 65.4 142 800 5,8206892495 Mill Creek 8,760 0 293 4.35 5.66 8.13 9.35 12.2 19.0 36.9 96.4 255 989 8,290

2006

6893100 Blue River 8,760 0 123 .02 .06 .45 .70 1.85 5.77 10.8 24.7 47.7 184 3,8806892495 Cedar Creek 8,710 .6 78.6 2.51 3.07 3.50 3.74 4.79 7.59 12.7 22.2 46.4 211 1,8606893390 Indian Creek 8,760 0 363 11.2 14.4 17.3 18.3 21.6 25.3 37.4 88.0 188 811 10,7006892360 Kill Creek 8,717 .5 48.0 .19 .35 .55 .68 1.05 3.82 6.28 13.6 27.2 99.0 1,6606892495 Mill Creek 8,760 0 106 2.52 2.98 3.91 5.10 6.97 10.1 16.4 36.9 73.4 360 3,450
12 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.—Continued [ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than] Calendar year and monitoring site Number of values Percent- age of hourly values missing Sample standard deviation Measurement at indicated frequency of exceedance Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum Specific conductance (μS/cm) 2003 6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Cedar Creek1 7,599 13.3 229 226 421 583 669 782 916 1,130 1,260 1,320 1,430 1,560 6893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Mill Creek 8,760 0 294 204 382 474 544 680 908 1,110 1,320 1,400 1,600 2,250 2004 6893100 Blue River2 7,300 .6 81.4 149 266 379 435 511 563 590 627 645 698 729 6892495 Cedar Creek 8,784 0 163 202 433 541 585 666 752 837 947 1,090 1,300 1,370 6893390 Indian Creek2 7,344 0 197 205 349 459 554 735 877 959 1,040 1,100 1,370 1,510 6892360 Kill Creek2 7,344 0 84.7 152 290 384 435 527 584 617 636 652 722 747 6892495 Mill Creek 8,784 0 504 156 363 482 551 730 905 1,030 1,370 2,168 3,060 4,540 2005 6893100 Blue River 8,760 0 84.9 164 316 405 460 516 589 624 646 675 769 832 6892495 Cedar Creek 8,656 1.2 111 192 368 500 555 657 743 787 829 844 916 1,000 6893390 Indian Creek 8,723 .4 397 222 340 500 621 822 933 1,020 1,460 1,880 2,553 2,970 6892360 Kill Creek 8,760 0 86.0 159 295 397 460 542 603 640 661 676 697 712 6892495 Mill Creek 8,654 1.2 260 242 371 489 576 736 894 965 1,230 1,380 1,720 2,270 2006 6893100 Blue River 8,760 0 88.6 143 315 436 491 567 625 675 704 713 731 752 6892495 Cedar Creek 8,760 0 126 162 368 519 624 727 810 861 904 929 1,059 1,240 6893390 Indian Creek 8,760 0 401 195 358 521 635 818 965 1,110 1,248 1,420 2,909 4,340

6892360 Kill Creek 8,691 .8 76.6 229 379 453 492 538 613 654 672 691 726 7356892495 Mill Creek 8,760 0 318 245 374 476 573 672 866 1,030 1,120 1,340 2,139 3,170
Methods 13

Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.—Continued[ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than]

Calendar year and 

monitoring site

Number 

of values

Percentage of 

hourly 

values 

missing

Sample 

standard 

deviation

Measurement at indicated frequency of exceedance

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum

pH (standard units)

2003

6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Cedar Creek1 7,597 13.3 0.301 7.6 7.6 7.7 7.8 7.9 8.1 8.3 8.6 8.7 8.9 9.16893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Mill Creek 8,760 0 .234 7.4 7.6 7.7 7.8 7.9 8 8.2 8.4 8.5 8.7 9.1

2004

6893100 Blue River2 7,299 .6 .166 7.6 7.7 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.3 8.56892495 Cedar Creek 8,784 0 .228 7.4 7.7 7.8 7.8 7.9 8.0 8.2 8.4 8.5 8.7 8.96893390 Indian Creek2 7,344 0 .230 7.3 7.4 7.5 7.5 7.6 7.8 7.9 8.0 8.2 8.6 8.86892360 Kill Creek2 7,344 0 .152 7.5 7.6 7.7 7.7 7.8 7.9 8.0 8.1 8.2 8.2 8.46892495 Mill Creek 8,784 0 .219 7.4 7.5 7.6 7.7 7.8 8.0 8.1 8.3 8.3 8.5 8.7

2005

6893100 Blue River 8,601 1.8 .218 7.3 7.4 7.5 7.6 7.8 8.0 8.1 8.2 8.2 8.3 8.56892495 Cedar Creek 8,658 1.2 .258 7.2 7.4 7.6 7.7 7.9 8.0 8.2 8.4 8.5 8.6 8.86893390 Indian Creek 8656 1.2 .271 7.1 7.2 7.3 7.4 7.5 7.7 7.8 8 8.3 8.6 9.16892360 Kill Creek 8,760 0 .165 7.5 7.6 7.6 7.7 7.8 7.9 8.0 8.1 8.2 8.2 8.36892495 Mill Creek 8,760 0 .218 7.4 7.5 7.6 7.7 7.8 8.0 8.1 8.3 8.4 8.5 8.7

2006

6893100 Blue River 8,165 6.8 .318 7.4 7.5 7.6 7.6 7.7 7.9 8.2 8.4 8.5 8.8 8.96892495 Cedar Creek 8,760 0 .286 7.3 7.4 7.5 7.6 7.7 7.8 8.0 8.3 8.4 8.7 9.06893390 Indian Creek 8,760 0 .272 6.9 7.0 7.1 7.2 7.3 7.5 7.7 7.9 8.0 8.3 8.76892360 Kill Creek 8,691 .8 .232 7.3 7.4 7.6 7.7 7.8 8.0 8.2 8.3 8.3 8.5 8.76892495 Mill Creek 8,760 0 .308 7.3 7.4 7.5 7.6 7.7 7.9 8.2 8.4 8.5 8.6 8.8
14 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.—Continued [ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than] Calendar year and monitoring site Number of values Percent- age of hourly values missing Sample standard deviation Measurement at indicated frequency of exceedance Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum Water temperature (°C) 2003 6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Cedar Creek1 7,599 13.3 8.57 0 1.0 2.6 3.7 9.1 17.3 23.5 27.6 28.8 30.6 31.8 6893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Mill Creek 8,760 0 9.37 .2 .7 1.6 2.4 4.3 15.2 22.3 27.6 28.9 30.6 32.7 2004 6893100 Blue River2 7,296 .7 7.01 .1 .5 2.9 6.5 11.2 17.5 22.0 24.2 25.8 28.3 29.9 6892495 Cedar Creek 8,784 0 8.61 0 .1 .4 1.0 7.0 15.4 22.2 24.5 26.1 28.5 31.1 6893390 Indian Creek2 7,344 0 6.34 1.3 3.5 6.6 8.4 12.8 18.9 22.8 24.9 26.3 28.7 31.8 6892360 Kill Creek2 7,344 0 7.22 .2 .4 3.0 6.2 11.3 18.0 22.6 24.7 26.2 28.2 29.6 6892495 Mill Creek 8,784 0 8.72 0 0 .3 .9 6.9 15.6 22.4 24.7 26.2 28.7 30.9 2005 6893100 Blue River 8,760 0 8.98 -.1 .2 1.2 2.0 6.4 15.0 22.9 26.0 27.4 29.4 32.4 6892495 Cedar Creek 8,706 .6 8.96 -.1 .1 .7 2.4 6.5 15.0 23.1 26.2 27.4 29.1 30.5 6893390 Indian Creek 8,723 .4 8.02 1.1 2.0 3.7 4.9 8.6 16.3 23.4 26.2 27.6 29.8 32.5 6892360 Kill Creek 8,760 0 9.08 0 .3 .5 1.9 6.5 14.9 23.2 26.1 27.6 29.5 32.1 6892495 Mill Creek 8,760 0 9.06 .1 .3 .7 2.1 6.8 15.2 23.3 26.4 28.0 29.4 30.5 2006 6893100 Blue River 8,760 0 8.93 .2 .8 2.4 3.5 6.4 14.7 23.2 27.0 28.4 30.8 32.4 6892495 Cedar Creek 8,760 0 8.97 .1 .7 2.2 3.3 6.4 14.8 23.8 26.9 28.1 30.3 32.6 6893390 Indian Creek 8,760 0 7.66 1.4 2.8 5.5 6.9 9.3 15.8 23.5 26.6 28.1 30.5 33.0

6892360 Kill Creek 8,691 .8 9.00 .5 1.3 2.5 3.4 6.2 15.0 23.6 27.1 28.4 30.4 32.96892495 Mill Creek 8,760 0 9.01 .2 .9 2.5 3.7 6.9 15.3 24.1 27.2 28.5 30.7 32.6
Methods 15

Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.—Continued[ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than]

Calendar year and 

monitoring site

Number 

of values

Percentage of 

hourly 

values 

missing

Sample 

standard 

deviation

Measurement at indicated frequency of exceedance

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum

Turbidity (FNU)

2003

6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Cedar Creek1 7,599 13.3 68.3 E 0 2.2 4.7 6.0 7.8 11 18 30 45 205 >2,0006893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- --6892495 Mill Creek 8,704 .6 109 .2 .7 1.1 1.7 3.8 8.6 20 46 83 436 1,900

2004

6893100 Blue River2 7,199 2.0 80.1 1.2 1.7 3.2 5.8 8.6 13 25 51 92 365 1,1906892495 Cedar Creek 8,409 4.3 49.6 E 0 .7 1.0 2.0 5.8 9.8 17 26 39 130 1,9606893390 Indian Creek2 6,868 6.5 76.6 .3 1.1 1.7 2.0 2.9 4.6 12 42 98 410 9906892360 Kill Creek2 7,228 1.6 84.4 .1 2.1 4.4 5.8 9.1 14 25 46 76 364 1,2006892495 Mill Creek 8,726 .7 114 1.0 1.5 2.0 2.6 4.0 8.0 20 48 95 490 1,820

2005

6893100 Blue River 8,724 .4 58.0 1.0 1.7 2.8 4.2 6.7 9.6 19 45 86 290 1,1706892495 Cedar Creek 8,654 1.2 74.6 E 0 1.0 2.0 2.7 5.0 8.0 13 26 54 300 1,5906893390 Indian Creek 8,723 .4 67.5 .4 .7 1.1 1.6 2.9 5.3 11 39 95 360 1,1206892360 Kill Creek 8,692 .8 59.2 .7 .7 1.0 1.8 5.1 8.6 14 32 68 310 1,4506892495 Mill Creek 8,573 2.1 103 1.8 3.2 4.0 4.7 6.7 12 25 62 120 589 1,180

2006

6893100 Blue River 8,760 0 72.2 1.6 2.5 3.4 4.0 5.2 8.0 13 28 57 279 1,8506892495 Cedar Creek 8,760 0 37.1 1.0 1.5 2.2 2.8 4.5 7.7 12 18 28 110 1,4906893390 Indian Creek 8,315 5.1 58.4 .6 1.3 1.9 2.2 3.2 5.5 11 32 66 268 1,1706892360 Kill Creek 8,526 2.7 37.1 E 0 .7 1.3 2.3 5.4 10 16 25 40 97 1,2306892495 Mill Creek 8,718 .5 60.5 .1 1.9 2.4 3.0 4.5 7.8 13 26 52 210 >2,000
16 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 4. Summary of continuous in-stream measured data and frequency of exceedance percentiles for streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen at five water-quality monitoring sites in Johnson County, northeast Kansas, 2003–06.—Continued [ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; FNU, formazin nephelometric units; mg/L, milligrams per liter; --, no data available; E, estimated; >, greater than] Calendar year and monitoring site Number of values Percent- age of hourly values missing Sample standard deviation Measurement at indicated frequency of exceedance Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile Median 50 per- centile 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maxi- mum Dissolved oxygen (mg/L) 2003 6893100 Blue River -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Cedar Creek1 7,538 13.9 3.18 1.2 3.9 5.4 5.9 7.1 8.9 11.7 13.8 15.6 17.9 22.9 6893390 Indian Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892360 Kill Creek -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6892495 Mill Creek 8,710 .6 3.47 1.8 4.8 6.0 6.7 8.1 9.9 12.3 16.6 17.5 18.5 21.0 2004 6893100 Blue River2 6,857 6.6 2.28 4.2 5.3 6.2 6.7 7.3 8.5 10.7 12.4 13.8 14.6 15.5 6892495 Cedar Creek 7,886 10.2 2.69 4.7 5.3 6.0 6.4 7.3 9.0 11.4 13.3 14.5 16.8 18.8 6893390 Indian Creek2 6,496 11.5 2.65 1.9 3.3 4.2 4.9 6.0 7.7 9.7 11.6 12.9 15.4 17.9 6892360 Kill Creek2 7,344 0 2.38 3.5 4.8 5.7 6.2 7.1 8.4 10.4 12.3 13.4 15.3 16.5 6892495 Mill Creek 8,064 8.2 3.82 5.0 5.8 6.6 7.1 8.1 10.3 13.4 17.5 18.8 20.7 24.0 2005 6893100 Blue River 8,340 4.8 3.05 1.8 2.7 4.2 5.5 6.6 8.0 11.7 13.1 13.9 14.8 15.8 6892495 Cedar Creek 8,567 2.2 2.96 3.1 3.9 5.2 5.8 7.2 9.3 11.8 13.7 14.6 15.9 17.4 6893390 Indian Creek 8,132 7.2 3.26 1.5 2.3 3.7 4.4 6.0 8.0 10.6 12.4 14.2 17.4 21.1 6892360 Kill Creek 8,702 .7 3.04 2.8 3.8 5.2 6.1 7.1 9.3 12.5 13.7 14.2 15.7 17.7 6892495 Mill Creek 8,475 3.3 3.29 3.0 4.6 5.8 6.6 7.7 9.8 12.9 15.1 16.1 17.5 21.8 2006 6893100 Blue River 8,612 1.7 3.33 2.0 3.0 4.1 4.6 6.0 7.9 11.4 13.5 14.4 16.1 17.8 6892495 Cedar Creek 8,653 1.2 3.40 3.2 4.1 4.8 5.4 7.1 9.2 12.1 14.4 15.9 18.3 21.4 6893390 Indian Creek 7,890 9.9 2.97 0.9 1.7 2.8 3.6 5.3 7.2 9.6 11.6 12.5 14.2 18.8

6892360 Kill Creek 8,402 4.1 3.24 1.8 3.3 4.4 5.1 6.2 8.4 11.5 13.2 14.0 17.4 21.26892495 Mill Creek 8,331 4.9 3.15 1.0 3.9 5.1 5.7 7.1 9.0 11.8 14.0 15.2 16.5 17.8

1Monitoring began in February of this year at this site.2Monitoring began March 1 of this year at this site.
Results of Continuous In-Stream Measurements 17

estimates, probability, uncertainty, and duration curves for the 

five monitoring sites are available on the World Wide Web at 

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

Several factors can contribute to variability in the regression models. These factors include equipment limitations 

associated with obtaining accurate measurements, variability 

in sample collection, processing, and analysis, and unmixed or 

rapidly changing stream conditions.

Estimation of Constituent Concentrations, 

Densities, Loads, and Yields

Continuous (hourly) constituent concentrations and loads 

were estimated using the regression models. In this report, 

in-stream and estimated continuous concentration data were 

evaluated from March 2004 through December 2006 when all 

five monitoring sites were operating simultaneously. Estimated 

load and yield data were evaluated for 2005 and 2006, the two 

full calendar years when all five monitor sites were operating. Seasonal comparisons were made by grouping the data 

into three periods consistent with the seasonal periods used 

by KDHE and determined primarily by streamflow. March 

through July represent the spring and early summer runoff 

season, August through October represent variable streamflow 

associated with late summer and fall, and November through 

February represent the winter low-flow season. Additional 

data are available at http://ks.water.usgs.gov/Kansas/rtqw/.

Continuous data occasionally were missing during 

periods when the water-quality instruments malfunctioned, 

extreme weather conditions occurred, or during routine maintenance visits. Generally, after initial equipment installation, 

less than 2 percent of the hourly values were missing from 

each site annually (table 4). Missing data were not estimated 

during these periods. In addition, a specified range of operation is associated with each sensor on the in-stream monitor. 

Conditions in the monitored streams remained within these 

specified ranges except for turbidity. Turbidity sensors used 

in the study (YSI model 6136, Yellow Springs Instruments, 

Yellow Springs, Ohio) were capable of measuring a range 

from less than 3 to about 2,000 formazin nephelometric units 

(FNUs), depending on the individual sensor. Turbidity conditions rarely exceeded the upper measurement limit during the 

study. Five hourly turbidity values were affected by sensor 

maximization at Mill Creek in 2003 and 19 hourly turbidity 

values were affected by sensor maximization at Kill Creek in 

2004. When the actual turbidity was more than the maximum 

a sensor could measure, the sensor reported only the maximum 

value. That maximum sensor value was used to estimate the 

concentrations and loads.

For response variables that were log-transformed, 

retransformation of regression-estimated concentrations was 

necessary. Retransformation can cause bias (underestimation) 

in the estimated constituent loads when adding individual 

estimates over a period of time (Helsel and Hirsch, 2002). 

Therefore, a log-transformation bias correction factor, Duan’s 

smearing estimator (Duan, 1983) was calculated and applied 

to the estimated hourly concentration values to correct for this 

underestimation.

Constituent loads and yields were estimated from continuous concentration estimates, continuous streamflow data, and 

respective drainage basin area. Hourly constituent loads were 

calculated for each constituent at each of the five monitoring 

sites by multiplying hourly estimated concentrations by hourly 

streamflow and a conversion factor. Seasonal and annual loads 

were calculated by summing hourly load estimates during the 

specified period of time. Constituent yields from the contributing drainage areas were calculated by dividing total loads by 

corresponding drainage areas to determine constituent concentration per square mile. Yields are important for comparing 

relative contributions of each basin.

Duration Curves

Duration curves are used to compare conditions among 

the five monitoring sites from March 2004 through December 2006 when monitors at all sites were operating simultaneously. Duration curves are cumulative distribution functions 

of all measurements (hourly values, in this report) within a 

specified period of time. The curves show the percentage of 

time specific conditions were equaled or exceeded, or the 

frequency of exceedance (Maidment, 1993). Historically, 

streamflow duration curves have been used in hydrologic 

studies to describe frequency and magnitude characteristics of 

streamflow (Searcy, 1959; Vogel and Fennessey, 1995). More 

recently, duration curves have been used to describe frequency 

and magnitude of continuous water-quality data (Rasmussen 

and Ziegler, 2003; Rasmussen and others, 2005). Although 

several similar formulas exist for calculating plotting position, 

the Weibull formula (Weibull, 1939; Helsel and Hirsch, 2002) 

was used in this study.

Results of Continuous In-Stream 

Measurements

Streamflow

Hourly streamflow ranged from less than 1 ft3/s in Kill 

Creek (2004, 2005, and 2006) and the Blue River (2005 and 

2006) to 19,200 ft3/s in the Blue River (2004) (table 4). The 

largest median streamflow from March 2004 through 2006 

occurred in Indian Creek (fig. 4), which is the second largest drainage basin (63.1 mi2

) and the most urban of the five 

monitored basins (table 1). Median annual streamflow at 

all sites in 2006 was about one-half of the median annual 

streamflow in 2005, except at the Indian Creek site where the 

2006 median was only about 20 percent lower than the 2005 

median (table 4). At all continuous monitoring sites except 
18 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

the Blue River, the majority of streamflow during base-flow 

conditions originated from WWTF discharge (Lee and others, 

2005). Base flow is defined as the sustained flow of a stream 

in the absence of direct runoff, usually originating from 

ground water seepage, springs, and/or wastewater discharges. 

The Blue River was not affected by WWTF discharges at 

the monitoring site but was affected downstream from the 

site. The Indian Creek site was downstream from the largest 

magnitude of WWTF discharge received at the five monitoring sites (Lee and others, 2005), thus accounting for its larger 

streamflow during base-flow conditions. Kill Creek, the 

smallest and least urban of the monitored basins (48.6 mi2

, 

table 1), generally had the smallest streamflow except during minimum flows when Blue River streamflow was smallest. The Blue River, with the largest drainage area (65.7 mi2

, 

table 1), had the smallest streamflow during about 10 percent 

of the time (fig. 4) likely because of the lack of WWTF discharge at that site to sustain low flow. In 2005, 118 acre-ft of 

water was withdrawn from the Blue River approximately 1 to 

3 mi upstream from the monitoring site for sod farm irrigation (J. Bagley, Kansas Department of Agriculture, written 

commun., 2006) accounting for less than 1 percent of the total 

annual flow volume. Streamflow volumes and yields for the 

five monitoring sites from 2004–06 are provided in table 5.

Historical streamflow records (http://waterdata.usgs.gov/

ks/nwis) at two streamflow-gaging stations in Johnson County, 

each with periods of record of at least 30 years (Indian Creek 

at Overland Park, station 06893300, and Blue River at Stanley, 

station 06893080, fig. 1), indicated that the mean annual 

streamflow in 2005 was about 50 percent larger than the mean 

annual streamflow for the period of record. In 2006, streamflow at the Indian Creek station (06893300) was about 90 percent of the historic average streamflow and at the Blue River 

site (06893080) only about 40 percent of the historic average.

Annual differences in streamflow can be attributed to differences in precipitation. Average annual precipitation during 

the study period, calculated using the City of Overland Park’s 

online flood-warning system “Stormwatch” (http://www.

stormwatch.com) data from two to four collection sites within 

each watershed (depending on the number of Stormwatch 

sites within each watershed), indicated that annual precipitation in all watersheds was less in 2006 than in 2004 and 2005 

(table 6). Average annual precipitation in 2004 and 2005 was 

similar to the historical mean annual precipitation of 40 in. 

in all five watersheds except the Blue River watershed which 

received 8 in. more precipitation than normal (about 48 in.) 

in 2004. Precipitation in 2006 was less than normal, ranging 

from about 28 to 34 in.

Specific Conductance

Specific conductance is a measure of water’s ability to 

conduct an electrical current and is related to the concentration of ionized substances in water (Hem, 1992). Specific 

conductance is affected by soil and rock composition; size of 

the watershed, which affects contact with soil before runoff 

reaches streams; evaporation, which concentrates dissolved 

Figure 4. Duration curves for measured streamflow at five monitoring sites in Johnson County, 

Kansas, March 2004 through December 2006.

0

1

10

100

1,000

10,000

100,000

0 10 20 30 40 50

(median)

60 70 80 90 100

Streamflow, in cubic feet per second

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Results of Continuous In-Stream Measurements 19

solids; and contaminant sources, including agricultural and 

urban runoff (Hem, 1966; Jordan and Stamer, 1995). In most 

Kansas streams, specific conductance is larger during low flow 

because of ground-water contributions of dissolved carbonate 

minerals in underlying limestone (Jordan and Stamer, 1995). 

Specific conductance in stream water can increase as a result 

of point-source discharges from WWTFs and urban runoff 

(Pope and Putnam, 1997).

Specific conductance at the five monitoring sites 

ranged from about 150 μS/cm in the Blue River and Kill and 

Mill Creeks to 4,540 μS/cm in Mill Creek (table 4). From 

March 2004 through 2006, specific conductance was nearly 

always largest at the Indian Creek site, followed by the Mill 

Creek site, the two most urban sites and the two sites with the 

largest WWTF contribution (fig. 5) which can lead to elevated 

specific conductance. All sites except Kill Creek show sharp 

increases in specific conductance during the 0- to 15-percent 

exceedance frequency (fig. 5), likely as a result of road-salt 

application. Specific conductance conditions in the Blue River 

and Kill Creek, both mainly undeveloped watersheds, were 

similar during the monitoring period. Cedar Creek, which also 

is predominantly undeveloped, had a median specific conductance about 25 percent larger than the Blue River and Kill 

Creek (fig. 5), possibly because of bedrock dissolution from 

large rock quarries in the upstream portions of the watershed. 

The Blue River and Kill Creek sites did not show major effects 

from road-salt application in 2005 (fig. 5).

pH

pH is a measure of the effective hydrogen ion concentration and is used as an index of the status of chemical and 

biological equilibrium reactions in water (Hem, 1992). The 

pH of natural water generally ranges from 6.5 to 8.5 standard 

units (Hem, 1992). Kansas aquatic-life-support criteria require 

that pH in streams measure not less than 6.5 and not more 

than 8.5 standard units (Kansas Department of Health and 

Environment, 2005).

pH ranged from 6.9 (Indian Creek in 2006) to 9.1 standard units (Cedar, Indian, and Mill Creeks) (table 4). From 

March 2004 through 2006, exceedances of the upper criterion of 8.5 standard units occurred at the Cedar, Indian, and 

Mill Creek sites less than 3 percent of the time (fig. 6). pH of 

streams in northeastern Kansas has been found to be slightly 

alkaline primarily because of the buffering capacity of the 

surficial soils and rocks (Jordan and Stamer, 1995). pH at the 

Indian Creek site remained less than pH at the other Johnson County sites most of the time, except during the 0- to 

10-percent frequency-of-exceedance period when pH sharply 

increased and exceeded pH at the other sites (fig. 6). Urban 

runoff can be more acidic (Welch and Lindell, 1992), resulting 

in lesser values of pH at the Indian Creek site.

Table 5. Mean daily streamflow, annual streamflow volume, and annual streamflow yield at five water-quality monitoring sites in Johnson County, 

northeast Kansas, 2004–06.

[acre-ft, acre-feet; --, not available]

Monitoring site 

(fig. 1)

2004 2005 2006

Mean 

daily 

streamflow 

(cubic 

feet per 

second)

Annual 

streamflow 

volume 

(acre-ft)

Annual 

streamflow 

yield 

[acre-ft/

mi2)/yr]

Mean 

daily 

streamflow 

(cubic 

feet per 

second)

Annual 

streamflow 

volume 

(acre-ft)

Annual 

streamflow yield 

[acre-ft/

mi2)/yr]

Mean 

daily 

streamflow 

(cubic 

feet per 

second)

Annual 

streamflow 

volume 

(acre-ft)

Annual 

streamflow 

yield 

[acre-ft/

mi2)/yr]

Blue River at Kenneth Road -- -- -- 66.7 48,300 735 19.2 13,900 212

Cedar Creek near DeSoto 51.2 37,100 634 56.1 40,600 694 18.5 13,400 229

Indian Creek at State Line 

Road

-- -- -- 99.4 72,000 1,140 71.6 51,800 821

Kill Creek at 95th Street -- -- -- 48.1 34,800 717 9.5 6,880 142

Mill Creek at Johnson Drive 56.4 40,800 694 71.4 51,700 879 27 19,500 332

 

Table 6. Average annual precipitation in five watersheds of 

Johnson County, northeast Kansas, 2003–06 (data source 

http://www.stormwatch.com).

[--, not determined because collection sites were not yet operating]

Watershed 

(fig. 1)

Average annual precipitation, in inches

2003 2004 2005 2006

Blue River -- 48.4 37.7 34.0

Cedar Creek 29.9 42.2 41.9 28.0

Indian Creek -- 43.6 39.0 34.2

Kill Creek -- 43.4 44.2 28.1

Mill Creek 29.7 43.8 43.6 30.7
20 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 5. Duration curves for measured specific conductance at five monitoring sites in Johnson County, 

Kansas, March 2004 through December 2006.

Figure 6. Duration curves for measured pH at five monitoring sites in Johnson County, Kansas, 

March 2004 through December 2006. 

0

500

1,000

1,500

2,000

2,500

3,000

0 10 20 30 40 50 60 70 80 90 100

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

7.0

7.5

8.0

8.5

9.0

9.5

pH, in standard units

Maximum Kansas Department of

Health and Environment (2005)

aquatic-life-support criterion

(8.5 standard units)

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Results of Continuous In-Stream Measurements 21

Water Temperature

Water temperature has an important effect on the density of water, the solubility of constituents in water, specific 

conductance, pH, the rate of chemical reactions, and biological activity in water (Wilde and others, 2006). Kansas 

water-quality criteria require that discharges to streams 

not raise the water temperature more than 3oC or raise the 

temperature above 32oC (Kansas Department of Health and 

Environment, 2005).

Water temperature ranged from about 0oC at all sites 

except Indian Creek to about 32oC at all sites (table 4). All 

the sites demonstrated similar water temperature conditions 

except Indian Creek. From March 2004 through 2006, the 

temperature of Indian Creek, the most urban site and the site 

most affected by WWTF discharge, exceeded that of the other 

sites about 60 percent of the time (fig. 7). The largest difference in water temperature between Indian Creek and the 

other less urban sites occurred at low temperatures (during 

winter months) when the temperature at the Indian Creek site 

was 2.5 to 3oC warmer than the other sites (table 4). Besides 

being affected by warmer wastewater discharges, increased 

water temperature in urban streams is caused by the decrease 

in streamside shade from loss of riparian habitat, heating of 

runoff from roads and parking lots, and generally warmer temperatures formed by cities (Galli, 1991; LeBlanc and others, 

1997; Paul and Meyer, 2001).

Turbidity

Turbidity is caused by suspended and dissolved matter 

such as clay, silt, finely divided organic matter, plankton and 

other microscopic organisms, organic acids, and dyes (ASTM 

International, 2003; Anderson, 2005). Turbidity is affected by 

the amount of precipitation and runoff, intensity and duration 

of storms, slope of the river channel, geomorphic structure of 

the channel, origin of the water including point and nonpoint 

sources, and time of travel from the point of origin to the point 

of measurement. Biological activity, such as algal blooms, can 

increase turbidity. Particulates in water provide attachment 

sites for nutrients, pesticides, indicator bacteria, and other 

potential contaminants. Also, increased turbidity reduces light 

penetration and photosynthesis, smothers benthic habitats, and 

interferes with feeding activities. Very large values of turbidity for short periods of time may be less harmful than smaller 

values that persist (Wetzel, 2001). USEPA level III ecoregion 

40 recommended criteria for turbidity is 15.5 nephelometric turbidity units (U.S. Environmental Protection Agency, 

2003b). The instrument technology used in this study to 

measure turbidity in formazin nephelometric units (FNUs) is 

appropriate for comparison to the criteria, which are expressed 

in nephelometric turbidity units (NTUs).

Turbidity values ranged from less than 2 FNUs at all 

sites annually to about 2,000 FNUs at the Cedar and Mill 

Creek sites (table 4). During infrequent storms at the Mill and 

Kill Creek monitoring sites (less than 1 percent of the time), 

turbidity exceeded the maximum value the sensor was capable 

of measuring; therefore, the absolute maximum turbidity 

at those sites is unknown. From March 2004 through 2006 

turbidity values at the Blue River, Kill and Mill Creek sites 

were similar except within the 90- to 100-percent frequency 

range when the Kill Creek values dropped to nearly 0 (fig. 8). 

The Indian Creek site had the smallest turbidity most of the 

time (fig. 8), probably because of the high clarity of WWTF 

discharge, which dominates streamflow at that site most of the 

time (Lee and others, 2005). The largest turbidity measurements at all sites occurred during storm runoff. The USEPArecommended ecoregion criterion was exceeded 20 to 30 

percent of the time (fig. 8).

Dissolved Oxygen

The dissolved oxygen (DO) concentration in surface 

water is related primarily to photosynthetic activity of aquatic 

plants, atmospheric reaeration, and water temperature (Lewis, 

2006). Diffusion of oxygen across the air-water interface can 

be a major factor affecting DO concentrations for small, shallow streams with a high surface area to volume ratio (Huggins 

and Anderson, 2005). DO is an important factor in chemical reactions and the survival of aquatic organisms. Kansas 

aquatic-life- support criterion requires that DO concentrations 

are not less than 5.0 mg/L (Kansas Department of Health and 

Environment, 2005).

Continuous dissolved oxygen concentration ranged from 

about 1 mg/L at the Cedar Creek site in 2003 and the Indian 

and Mill Creek sites in 2006, to 24 mg/L at the Mill Creek 

site in 2004 (table 4). From March 2004 through December 

2006, DO concentrations were less than the KDHE criterion 

of 5.0 mg/L less than about 10 percent of the time at all sites 

except Indian Creek, which was less than the criterion about 

15 percent of the time (fig. 9A). Low DO at all sites generally coincided with higher water temperatures resulting in 

decreased oxygen solubility in water. More frequent low DO 

at Indian Creek likely was caused by WWTF discharges that 

contribute nutrients increasing growth of microorganisms that 

consume nutrients and reduce DO.

Low DO at all sites occurred during all three seasonal 

periods but most frequently at the Indian Creek site and 

during the August–October period (fig. 9B), corresponding 

with the lowest streamflow, warmest water temperatures, and 

likely high algal activity. Most DO values less than 5.0 mg/L 

at Blue, Cedar, and Kill also coincided with low-flow conditions during mid- to late summer. Streamflow reduced by 

irrigation withdrawals just upstream from the monitor may 

contribute to low DO values at the Blue River site during dry 

periods. Generally, larger DO concentrations were sustained 

at all sites during winter because the solubility of oxygen is 

greater in colder water (Hem, 1992). However, the largest DO 

concentrations (in excess of 20 mg/L at all sites except Blue 

River sometime during the monitoring period) occurred during 
22 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 8. Duration curves for measured turbidity at five monitoring sites in Johnson County, Kansas, 

March 2004 through December 2006.

Figure 7. Duration curves for measured water temperature at five monitoring sites in Johnson 

County, Kansas, March 2004 through December 2006.

0

5

10

15

20

25

30

35

40

Water temperature, in degrees Celsius

-5

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

1

10

100

1,000

10,000

Turbidity, in formazin nephelometric units (FNUs, YSI 6136 sensor)

U.S. Environmental Protection

Agency (2003a) recommended 

ecoregion criterion (15.5 FNUs) 

0

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Results of Continuous In-Stream Measurements 23

Figure 9. Duration curves for (A) measured dissolved oxygen at five monitoring sites in Johnson 

County, Kansas from March 2004 through December 2006 and (B) seasonal dissolved oxygen at 

the Indian Creek monitoring site for January 2005 through December 2006.

0

5

10

15

20

25

0

5

10

15

20

25

Dissolved oxygen concentration, in milligrams per liter (mg/L)

(A) Measured dissolved oxygen at five monitoring sites in Johnson 

 County, Kansas, March 2004−December 2006

Minimum Kansas Department

of Health and Environment (2005)

aquatic-life-support criterion (5 mg/L)

Minimum Kansas Department

of Health and Environment (2005)

aquatic-life-support criterion (5 mg/L)

March−July

August−October

November−February

(B) Seasonal dissolved oxygen at Indian Creek at State Line Road

 (station 06893390, fig. 1), January 2005−December 2006

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
24 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

spring and summer when algal activity is high. For example, at 

the Indian Creek site during 2005–06, DO generally was largest during the winter months (November–February), but the 

largest measurements occurred during about 10 percent of the 

time during the March–July period (fig. 9B).

Variability in Streamflow and Water-Quality 

Measurements

A typical example of the water-quality variability that 

occurred in Johnson County streams is provided in figures 10A

and 10B using August 2005 data from the Indian Creek monitoring site. Distinct daily fluctuations occurred in pH, water 

temperature, and DO until changes in streamflow disturbed the 

patterns (fig. 10A). Daily variability in pH and DO is an indication of photosynthetic activity and is affected by availability 

of sunlight and nutrients (Wetzel, 2001). During the day, photosynthesis by aquatic plants increases the amount of oxygen 

dissolved in the water and decreases dissolved carbon dioxide, 

thus increasing pH during the daytime. Oxygen is consumed 

and carbon dioxide is released during respiration and decomposition, which occur throughout the day and night, resulting 

in lower pH and DO during the night. pH and DO fluctuations 

generally were more extreme at sites immediately downstream 

from WWTFs, like the Indian Creek site, because of increased 

algal activity from increased nutrient contributions from 

WWTFs. Increases in pH and water temperature result in an 

increase in the toxicity of ammonia for fish (Kansas Department of Health and Environment, 2005).

Rapid changes in specific conductance and turbidity associated with changes in streamflow occurred in Johnson County 

streams, as seen in data from the Indian Creek monitoring 

site (fig. 10B). Typically, specific conductance decreases and 

turbidity increases in response to storm runoff. Three different 

streamflow response sequences occurred in August 2005 as a 

result of precipitation and runoff. During runoff on August 19, 

2005, turbidity increased to about 1,100 FNUs when streamflow peaked at about 1,400 ft3

/s. The following day, a much 

larger streamflow peak of more than 6,000 ft3/s was accompanied by a much smaller turbidity peak of about 600 FNUs. A 

similar response occurred about a week later. This indicates 

that the magnitude of the streamflow peak does not necessarily determine the magnitude of the turbidity peak. In both 

cases, turbidity increased from less than 40 FNUs to more than 

1,000 FNUs in less than 5 hours. Turbidity fluctuations are 

affected by the source of sediment (channel bank or bed, or 

overland erosion), distance from the source, rainfall intensity, 

and length of time since the last runoff occurrence. The two 

pairs of streamflow and turbidity peaks that occurred at the 

Indian Creek site August 19–20 (fig. 10B) likely represented 

runoff from the two primary watersheds upstream from the 

monitoring site (Indian and Tomahawk Creeks) arriving at 

different times.

Relation Between Streamflow and Turbidity

Correlations between continuously measured streamflow and turbidity values at each monitoring site (at the 

Cedar Creek site, for example, fig. 11) in 2005–06 are poor, 

with coefficients of determination (R2) ranging from 0.39 to 

0.55 (table 7). Although the largest turbidity values occurred 

during stormwater runoff, peak turbidity values most often do 

not coincide with peak streamflow values. Turbidity peaks can 

either precede or follow associated streamflow peaks. Effects 

of these differences in turbidity during the rising and falling limbs of streamflow peaks (hysteresis) can be seen in the 

curved pattern (red line) within the data plotted in figure 11. 

Because the relation between streamflow and turbidity is complex, alternative interpretive tools are useful.

Williams (1989) and Nistor and Church (2005) describe 

patterns of streamflow and suspended-sediment concentration 

and explain sediment sources and transport characteristics on 

the basis of observed patterns. According to Nistor and Church 

(2005), the most common pattern is the clockwise hysteresis 

loop (Type 2, fig. 12B), which indicates depletion of available 

sediment before the streamflow peak occurs. Counterclockwise hysteresis (Type 4, fig. 12C) indicates delayed sediment 

travel time resulting from the downstream distance of the 

measuring station from the sediment source (Williams, 1989). 

Single-line curves (Type 1, fig. 12A) occur when an unlimited 

supply of sediment is available throughout runoff resulting in 

simultaneous peaks in both suspended-sediment concentration 

and streamflow (Williams, 1989). Variations such as figureeight patterns and multiple loops (Type 2 or 4, fig. 12D) occur 

because of bank collapses and tributary inflows, and these patterns also are affected by changes in precipitation and runoff 

rates, sediment availability, and rates and distances of travel 

(Williams, 1989). According to Asselman (1999), suspended 

sediment originating from the stream channel typically causes 

larger turbidity values during the rising limb of a streamflow 

peak (clockwise hysteresis), and sediment originating from 

more distant basin sources often causes larger turbidity values 

during the falling limb (counterclockwise hysteresis).

Streamflow and turbidity data from the monitoring 

sites in the study area were examined for hysteresis patterns during various runoff periods (fig. 13). Generally, large 

runoff resulted in clockwise hysteresis patterns (fig. 13A, 

for example), indicating sediment depletion during runoff 

(Nistor and Church, 2005) and substantial sediment contributions likely from the stream channel (Asselman, 1999). Small 

runoff, which occurred more frequently but resulted in smaller 

turbidity values compared to larger runoff, often resulted in 

counterclockwise hysteresis patterns (fig. 13B, for example) 

indicating sediment likely originated from more distant basin 

sources (Asselman, 1999; Nistor and Church, 2005). The 

Indian Creek site experienced more runoff periods showing 

single-line curve characteristics (fig. 13C) than any other 

site, indicating unlimited sediment supplies during several 

runoff periods that occurred that year. Characterizing turbidity changes during varying streamflow conditions leads to a 
Results of Continuous In-Stream Measurements 25

Figure 10. Variability in (A) streamflow, pH, water temperature, and dissolved oxygen, and (B) specific conductance 

and turbidity at the Indian Creek monitoring site in Johnson County, Kansas, August 2005.

0

5

10

15

20

25

30

35

2 7 12 17 22 26

pH, in standard units

 Water temperature, in degrees Celsius

Dissolved oxygen, in milligrams per liter

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Streamflow , in cubic feet per second

Streamflow

pH

Water temperature

Dissolved oxygen

(A) Variability in streamflow, pH, water temperature, and 

 dissolved oxygen

0

200

400

600

800

1,000

1,200

10 12 14 16 18 20

August 2005

22 24 26 28 30

Specific conductance, in microsiemens per centimeter at 25 degrees Celsius

Turbidity, in formazin nephelometric units (YSI 6136 sensor) 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Streamflow

Specific conductance

Turbidity

(B) Variability in specific conductance and turbidity
26 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

better understanding of concentration and loading properties 

for sediment and sediment-associated constituents like bacteria 

and some nutrients.

Regression-Estimated Constituent 

Concentrations, Densities, Loads, and 

Yields

Regression models for estimating selected waterquality constituents at the five continuous monitoring sites 

are presented and discussed in this section, followed by 

regression-estimated concentrations, densities, loads, and 

yields. Three constituents (suspended sediment, chloride, and 

E. coli bacteria) are discussed in more detail than the others. 

These three particular constituents were selected for additional 

discussion because they represent three major categories of 

concern in Johnson County streams (sediment, major ions, 

and indicator bacteria) that have been identified as sources of 

water-quality impairment by KDHE (Kansas Department of 

Health and Environment, 2006a).

Regression Models

Regression models and summary statistics for estimating water-quality constituents in the five monitored streams 

in Johnson County are presented in table 8. Separate models were developed for each monitoring site. Models were 

included in table 8 if at least one significant (p-value less 

Table 7. Relation between hourly streamflow (y) and turbidity (x) measurements at five water-quality monitoring sites in Johnson County, northeast 

Kansas, 2005–06.

Continuous monitoring site 

(fig. 1)

Station number 

(fig. 1) Equation Coefficient of determination (R2

)

Blue River at Kenneth Road 06893100 y = 2.42x - 11.2 0.39

Cedar Creek near DeSoto 06892495 y = 1.80x + 6.93 .48

Indian Creek at State Line Road 06893390 y = 4.13x + 2.64 .47

Kill Creek at 95th Street 06892360 y = 2.41x - 15.0 .50

Mill Creek at Johnson Drive 06892513 y = 1.95x - 3.47 .55

Figure 11. Comparison of continuously measured (hourly) streamflow and turbidity at the Cedar 

Creek monitoring site, Johnson County, Kansas, January 2005 through December 2006.

y = 1.80x + 6.93

Values for rising

and falling limbs of

hydrograph for an

individual runoff 

event showing effects

of hysteresis

R2

 = 0.48

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

Turbidity, in formazin nephelometric units (YSI 6136 sensor)

Streamflow, in cubic feet per second
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 27

than 0.05) explanatory variable was found. Summaries of 

discrete-sample data in table 8 may not identically match 

summaries in other tables within this report because table 8 

presents specific information for each site and constituent, and 

models require each discrete-sample data point (response variable) to be paired with available explanatory variable data.

Uncertainties associated with each model varied because 

of the number of samples collected, water-quality conditions 

at the time of sample collection including rapidly changing 

conditions, cross-section variability during sample collection, 

sampling and analytical error, and other factors affecting independent variables. Generally, for most constituents, models for 

the less urban sites (Blue River and Kill Creek) contained less 

variability than models for the more urban sites (Indian and 

Mill Creeks). This is because water quality in urban areas is 

more complex as a result of multiple sources and often altered 

pathways (Driver and Troutman, 1989).

Specific conductance and turbidity were the most 

common explanatory variables used in the models. Specific 

conductance is the primary explanatory variable for models 

estimating major ions because of the strong relation between 

specific conductance and dissolved ions. Turbidity was the primary explanatory variable for constituents associated with particulates, such as suspended-sediment concentration, unfiltered 

nutrient species, and fecal-indicator bacteria because these 

constituents attach to sediment particles. Most of the models 

include one of these two explanatory variables. However, some 

of the models also included streamflow as an explanatory variable, and several of the nutrient models included seasonal sine 

and cosine variables, indicative of the seasonal nature of some 

nutrient sources.

Figure 12. Common streamflow and suspended-sediment hysteresis patterns, types, and sediment source explanations 

[adapted from Williams (1989) and Nistor and Church (2005)].

C

Time

Concentration

Streamflow

Q

C Q

Q C

C Q

(A)

Type 1 – Unlimited sediment supply

(B)

Type 2 – Limited sediment supply

(C)

Type 4 - Distant source of sediment, 

new source, or bank collapse

(D)

Type 2 or 4 Variation – New sediment

 source or bank collapse

 

Suspended-sediment

concentration (C) 

and streamflow (Q) 

over time

Suspended-sediment 

concentration over 

the storm hydrograph
28 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 13. Examples of hysteresis patterns in streamflow and turbidity data from selected monitoring sites in Johnson County, northeast 

Kansas, 2005 (arrows indicate direction of hysteresis).

0

100

200

300

400

500

600

700

800

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

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

5/18/04 5/19/04 5/19/04 5/20/04

0

100

200

300

400

500

600

700

800

Streamflow

Turbidity

0

100

200

300

400

500

600

0 500 1,000 1,500

Turbidity, in formazin nephelometric units (YSI 6136 sensor)

Turbidity, in formazin nephelometric units ( YSI 6136 sensor)

0

200

400

600

800

1,000

1,200

1,400

Streamflow

1/3/05 1/3/05 1/4/05 1/4/05

, in cubic feet per second Streamflow, in cubic feet per second Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

0

100

200

300

400

500

600

Streamflow

Turbidity

Streamflow

Turbidity

0

100

200

300

400

500

600

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

0

1,000

2,000

3,000

4,000

5,000

6,000

8/26/05 8/26/05 8/26/05 8/26/05 8/27/05 8/27/05

August 2005

January 2005

24-hour intervals, May 2004

0

100

200

300

400

500

600

(A) Cedar Creek near DeSoto (station 06892495, fig. 1)

(B) Blue River at Kenneth Road (station 06893100, fig. 1)

(C) Indian Creek at State Line Road (station 06893390, fig. 1)
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 29

Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias correction 

factor 

(Duan, 

1983)

Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Suspended-sediment concentration (SSC), mg/L

Blue River at Kenneth Road logSSC = 1.16logTBY-0.140 0.96 0.162 1.05 19 SSC 7–4,170 630 440 977

TBY 5–1,270 278 250 312

Cedar Creek near DeSoto logSSC = 1.17logTBY-0.116 .97 .135 1.05 21 SSC 4–2,060 429 206 551

TBY 5–905 203 123 249

Indian Creek at State Line Road logSSC = 1.10logTBY+0.068 .96 .205 1.10 22 SSC 2–3,530 711 299 992

TBY 2–1,010 267 176 285

Kill Creek at 95th Street logSSC = 1.16logTBY-0.111 .98 .121 1.03 24 SSC 7–3,690 736 288 1,020

TBY 5–1,230 303 183 332

Mill Creek at Johnson Drive logSSC = 1.02logTBY+0.144 .95 .216 1.11 22 SSC 4–2,890 654 242 821

TBY 2–1,100 353 219 379

Sites combined logSSC = 1.12logTBY-0.020 .96 .172 1.08 107 SSC 2–4,170 285 169 314

TBY 2–1,270 642 263 883

Total suspended solids (TSS), mg/L

Blue River at Kenneth Road logTSS = 1.14logTBY-0.179 .96 .166 1.06 18 TSS 3.0–1,560 428 315 321

TBY 5.3–1,270 277 210 321

Cedar Creek near DeSoto logTSS = 1.23logTBY-0.271 .96 .167 1.08 21 TSS 3.0–1,690 391 171 526

TBY 5.0–905 195 102 253

Indian Creek at State Line Road logTSS = 1.03logTBY+0.194 .96 .179 1.07 22 TSS 5.0–2,880 546 250 802

TBY 2.0–1,010 247 155 289

Kill Creek at 95th Street logTSS = 1.14logTBY-0.150 .93 .246 1.11 24 TSS 3.0–3,380 627 239 887

TBY 2.9–1,230 297 146 338

Mill Creek at Johnson Drive logTSS = 0.985logTBY+0.242 .95 .228 1.13 22 TSS 4.0–2,780 661 210 822
30 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias cor- rection factor (Duan, 1983) Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Acid neutralizing capacity (ANC), mg/L as calcium carbonate

Blue River at Kenneth Road logANC = 0.846logSC-0.0418 0.82 0.0733 1.01 19 ANC 67–270 154 160 54

SC 172–658 430 456 153

Cedar Creek near DeSoto logANC = 0.433logSC+0.937 .44 .0912 1.00 22 ANC 70–224 141 136 38

SC 246–1,300 636 599 268

Indian Creek at State Line Road logANC = 0.360logSC+1.03 .60 .115 1.02 24 ANC 50–205 114 120 43

SC 211–3,710 886 498 986

Kill Creek at 95th Street logANC = 0.497logSC+0.901 .39 .120 1.01 25 ANC 86–270 156 140 57

SC 160–675 389 366 161

Mill Creek at Johnson Drive logANC = 0.413logSC+0.999 .52 .101 1.01 22 ANC 80–255 148 150 46

SC 227–1,740 739 561 442

Dissolved solids (DS), mg/L

Blue River at Kenneth Road logDS = 0.778logSC+0.390 .88 .0521 1.01 23 DS 125–400 275 265 85

SC 172–658 432 456 155

Cedar Creek near DeSoto logDS = 0.928logSC-0.0194 .98 .0269 1.00 26 DS 27–793 385 372 181

SC 246–1,300 662 624 284

Indian Creek at State Line Road logDS = 0.951logSC-0.0865 .98 .0509 1.01 28 DS 102–2,030 474 277 493

SC 211–3,710 825 428 931

Kill Creek at 95th Street logDS = 0.739logSC+0.490 .89 .0523 1.01 26 DS 130–480 251 218 93

SC 160–675 388 356 168

Mill Creek at Johnson Drive logDS = 0.886logSC+0.107 .95 .0515 1.01 29 DS 190–960 439 344 213

SC 227–1,740 735 563 422
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 31

Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias correction 

factor 

(Duan, 

1983)

Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Calcium (Ca), dissolved, mg/L

Blue River at Kenneth Road logCa = 1.08logSC-1.10 0.95 0.0459 1.00 19 CA 21–101 58 60 24

SC 172–658 430 456 153

Cedar Creek near DeSoto logCa = 0.562logSC+0.198 .68 .0721 1.01 22 CA 28–95 59 58 16

SC 246–1,300 636 599 268

Indian Creek at State Line Road logCa = 0.798logSC-0.562 .88 .0808 1.02 22 CA 15–83 41 29 22

SC 211–1,610 538 396 356

Kill Creek at 95th Street logCa = 1.02logSC-0.958 .90 .0662 1.01 25 Ca 18–105 50 44 25

SC 160–675 389 366 161

Mill Creek at Johnson Drive logCa = 0.718logSC-0.233 .79 .0958 1.02 23 CA 28–133 65 55 31

SC 227–1,740 716 559 434

Magnesium (Mg), dissolved, mg/L

Blue River at Kenneth Road logMg = 1.09logSC-2.04 .96 .0423 1.00 19 Mg 2.6–11 6.8 7.0 2.8

SC 172–658 430 456 153

Cedar Creek near DeSoto logMg = 0.824logSC-1.36 .89 .0527 1.01 22 Mg 3.6–15 8.8 8.4 2.9

SC 172–658 636 599 268

Indian Creek at State Line Road logMg = 1.05logSC-2.04 .90 .0944 1.02 22 Mg 2.0–17 7.2 4.8 5.0

SC 211–1,610 538 393 356

Kill Creek at 95th Street logMg = 0.997logSC-1.77 .93 .0531 1.01 26 Mg 2.2–11.7 6.5 6.2 2.7

SC 160–675 383 356 161

Mill Creek at Johnson Drive logMg = 0.837-logSC-1.40 .82 .100 1.03 23 Mg 3.5–18 9.6 7.4 4.9

SC 227–1,740 716 559 434
32 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias cor- rection factor (Duan, 1983) Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Sodium (Na), dissolved, mg/L

Blue River at Kenneth Road logNa = 1.22logSC-2.02 0.85 0.0961 1.02 19 Na 4.9–36 16 15 8.1

SC 172–658 430 456 153

Cedar Creek near DeSoto logNa = 1.60logSC-2.84 .94 .0720 1.01 23 Na 12–152 50 42 37

SC 246–1,300 642 618 264

Indian Creek at State Line Road logNa = 1.34logSC-2.02 .97 .0936 1.02 25 Na 8.2–524 98 49 149

SC 211–3,710 864 444 972

Kill Creek at 95th Street logNa = 1.26logSC-2.09 .89 .0876 1.02 25 Na 3.5–29 15 16 7.4

SC 160–675 389 366 161

Mill Creek at Johnson Drive logNa = 1.38logSC-2.21 .93 .0978 1.04 23 Na 11–206 59 43 55

SC 227–1,740 716 559 434

Sulfate (SO4), dissolved, mg/L

Blue River at Kenneth Road logSO4 = 1.29logSC-1.92 .85 .0906 1.02 18 SO4 8.8–76 32 30 16

SC 172–658 443 470 145

Cedar Creek near DeSoto logSO4 = 1.27logSC-1.69 .89 .0851 1.02 18 SO4 23–196 76 64 46

SC 246–1,300 626 580 272

Indian Creek at State Line Road logSO4 = 1.28logSC-1.84 .87 .1208 1.04 22 SO4 11–122 47 29 36

SC 211–1,010 504 393 275

Kill Creek at 95th Street logSO4 = 1.14logSC-1.45 .82 .1025 1.03 23 SO4 7.5–60 33 28 15

SC 160–675 390 373 153

Mill Creek at Johnson Drive logSO4 = 1.14logSC-1.42 .72 .1257 1.05 18 SO4 15–116 54 44 29

SC 227–968 544 545 210
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 33

Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias correction 

factor 

(Duan, 

1983)

Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Chloride (Cl), dissolved, mg/L

Blue River at Kenneth Road logCl = 1.26logSC-1.93 0.73 0.142 1.05 19 Cl 8.0–60 26 23 15

SC 172–658 430 456 153

Cedar Creek near DeSoto logCl = 1.76logSC-3.18 .92 .0944 1.02 22 Cl 10–270 66 51 59

SC 246–1,300 636 599 268

Indian Creek at State Line Road logCl = 1.53logSC-2.43 .94 .160 1.06 27 Cl 9–1,680 222 69 393

SC 211–5,710 428 69 1,320

Kill Creek at 95th Street logCl = 1.21logSC-1.91 .66 .168 1.07 25 Cl 5–50 18 16 11

SC 160–675 389 366 161

Mill Creek at Johnson Drive logCl = 1.48logSC-2.30 .92 .110 1.05 23 Cl 15–366 96 63 96

SC 227–1,740 716 559 434

Sites combined logCl = 1.63logSC-2.82 .87 .179 1.09 116 Cl 5–1,680 91 37 208

SC 160-5,710 664 493 718

Nitrogen nitrate (NO3), dissolved, mg/L

Blue River at Kenneth Road logNO3 = 0.224logQ-0.812 .62 .237 1.14 20 NO3 0.23–7.83 .61 .63 .32

Q 0.2–10,900 1,578 322 3,110

Cedar Creek near DeSoto logNO3 = -0.119logQ+0.500 .34 .297 1.47 21 NO3 0.25–7.83 1.68 1.12 1.65

(Poor model) Q 2.2–4,350 637 288 991

Indian Creek at State Line Road logNO3 = -0.0005SC+2.06logSC-4.97 .79 .212 1.11 24 NO3 0.41–10.4 3.2 2.01 3.02

SC 211–3,710 886 498 986

Kill Creek at 95th Street logNO3 = 0.284logQ-1.02 .37 .416 1.47 25 NO3 0.04–1.97 .64 .55 .51

(Poor model)

Mill Creek at Johnson Drive logNO3 = 0.146logQ+1.47logSC-4.30 .72 .205 1.1 23 NO3 0.27–9.29 1.92 1.36 2.04

SC 227–1,740 716 559 434Q 4.4–2,780 634 478 821
34 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias cor- rection factor (Duan, 1983) Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Orthophosphorus (OrthoP), mg/L

Blue River at Kenneth Road logOrthoP = 0.274logTBY-1.79sin 

(2*pi*day/365)-.082cos(2*pi*day/365)-1.78

0.68 0.170 1.06 19 OrthoP 0.01–0.12 0.06 0.06 0.03

TBY 3.9–1,270 263 169 318

Cedar Creek near DeSoto logOrthoP = -0.361logQ-0.085 .57 .331 1.37 21 OrthoP 0.04–2.22 .39 .21 .5

Q 2.2–4,350 637 288 991

Indian Creek at State Line Road logOrthoP= -0.0005SC+2.30logSC-6.31 .77 .249 1.40 25 OrthoP 0.06–2.76 .67 .38 .74

SC 211–3,710 864 444 972

Kill Creek at 95th Street No significant explanatory variables -- -- -- -- OrthoP 0.02–0.73 .13 .1 .14Mill Creek at Johnson Drive logOrthoP = 1.47logSC-0.265sin 

(2*pi*day/365)-0.019cos(2*pi*day/365)-4.83

.61 .284 1.17 23 OrthoP 0.02–1.5 .29 .18 .34

SC 227–1,741 716 559 434

Nitrogen, ammonia (NH3) dissolved, mg/L

Blue River at Kenneth Road logNH3 = 0.194logTBY-1.70 .22 .294 1.24 18(3) NH3 ‹0.02–0.26 .06 .04 .06

(Poor model)

Cedar Creek near DeSoto logNH3 = 0.264sin(2*pi*day/365)- 

0.083cos(2*pi*day/365)-1.40 (Poor model)

.32 .262 1.00 22(7) NH3 ‹ 0.02–0.12 .05 .04 .03

Indian Creek at State Line Road logNH3 = 0.256sin(2*pi*day/365)- 

0.180cos(2*pi*day/365)-0.212logQ-0.136

.54 .311 1.20 25(1) NH3 0.04–1.27 .34 .19 .35

Q 14–9,830 1,661 872 2,505

Kill Creek at 95th Street logNH3 = 0.274logTBY-2.03 .41 .250 1.16 24(11) NH3 0.01–0.17 .05 .03 .04

TBY 2.9–1,230 289 146 338

Mill Creek at Johnson Drive (Poor model) -- -- -- -- NH3 ‹0.02–0.34 .06 .05 .07
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 35

Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias correction 

factor 

(Duan, 

1983)

Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Nitrogen, ammonia plus organic (DON), dissolved, mg/L

Blue River at Kenneth Road No significant explanatory variables -- -- -- -- DON 0.07–2.40 0.64 0.54 0.49Cedar Creek near DeSoto logDON = 0.003TBY-0.3104 0.25 0.126 1.00 22 DON 0.3–1.0 .58 .60 .19

(Poor model)

Indian Creek at State Line Road logDON = 0.350logSC-0.945 .50 .134 1.05 25 DON 0.5–2.6 1.14 1.1 .53

SC 211–3,710 864 444 972

Kill Creek at 95th Street logDON = 0.264logTBY+0.0570 .43 .228 1.00 25 DON 0.2–1.3 .61 .57 .29

TBY 2.9–1,230 293 152 332

Mill Creek at Johnson Drive logDON = 0.127logTBY-0.548 .50 .122 1.04 23 DON 0.2–1.0 .54 .50 .20

TBY 2.0–1,100 339 149 378 

Nitrogen, ammonia plus organic (TON), total, mg/L

Blue River at Kenneth Road logTON = 0.472logTBY-0.862 .86 .141 1.05 18 TON 0.3–7.6 1.8 1.3 1.71

TBY 5.3–1,270 277 210 321

Cedar Creek near DeSoto logTON = 0.267logTBY-0.441 .63 .155 1.06 22 TON 0.4–3.1 1.3 1.1 .79

TBY 2.4–905 186 85 250

Indian Creek at State Line Road logTON = 0.0006TBY+0.180 .65 .124 1.04 24 TON 0.89–8.04 2.55 1.8 1.56

TBY 2–1,010 227 122 284

Kill Creek at 95th Street logTON = 0.0010TBY-0.280 .74 .207 1.38 25 TON 0.3–6.2 1.73 1.1 1.53

TBY 2.9–1,230 293 152 332

Mill Creek at Johnson Drive logTON = 0.0006TBY+0.1331logTBY-0.392 .89 .131 1.04 23 TON 0.4–5.80 1.73 1.1 1.53

TBY 2–1,100 339 149 378
36 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias cor- rection factor (Duan, 1983) Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Nitrogen, total (TN), mg/L

Blue River at Kenneth Road logTN = 0.111logQ+0.0004TBY-0.0585 0.78 0.153 1.06 18 Q 0.2–10,900 1,730 586 3,250

TN 0.6–8.8 2.5 2.4 1.9TBY 3.9–1,270 268 180 327

Cedar Creek near DeSoto No significant explanatory variables -- -- -- -- TN 1.4–9.2 3.0 2.5 1.6Indian Creek at State Line Road logTN = -0.173logTBY+0.126sin(2*pi*day/ 

365) +0.0302cos(2*pi*day/365)+0.986

.61 .146 1.05 24 TN 2.3–13 5.6 5.4 2.9

TBY 1.0–1,010 227 122 284

Kill Creek at 95th Street logTN = 0.423logTBY-0.624 .76 .178 1.08 25 TN 0.4–7.3 2.4 2.0 1.8

TBY 2.9–1,230 293 152 332

Mill Creek at Johnson Drive logTN = 0.0006logTBY+0.0483sin(2*pi*day/ 

365)+ 0.2205cos(2*pi*day/365)+0.296

.61 .187 1.09 23 TN 0.1–11 3.7 2.7 2.5

TBY 2.0–1,100 339 149 378

Phosphorus, total (TP), mg/L

Blue River at Kenneth Road TP = 0.0012TBY+0.152 .88 .099 1.00 19 TP 0.1–2.5 .52 .38 .54

TBY 3.9–1,270 263 169 318

Cedar Creek near DeSoto No significant explanatory variables -- -- -- -- TP 0.2–2.4 .69 .59 .49Indian Creek at State Line Road logTP = -0.299logQ+0.0009TBY+0.586 .62 .144 1.05 23 Q 14–9,830 1431 519 2,358

TP 0.5–3.0 1.2 1.0 .71TBY 1.0–1,010 229 101 290

Kill Creek at 95th Street TP = 0.0015TBY+0.199 .81 .222 1.00 24 TP 0.1–2.1 .60 .40 .50

TBY 2.9–1,230 262 146 300

Mill Creek at Johnson Drive logTP = 0.0008TBY+0.0222sin(2*pi*day/365)+ 

0.156cos(2*pi*day/365)-0.426

.70 .183 1.10 22 TP 0.2–2.4 .87 .63 .65

TBY 2.0–1,100 341 144 386
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 37

Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias correction 

factor 

(Duan, 

1983)

Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Fecal coliform bacteria (FCB), colonies per 100 milliliters

Blue River at Kenneth Road logFCB = 1.25logTBY+0.697 0.77 0.581 1.96 20 FCB 9–26,000 6,850 2,850 8,710

TBY3–1,270 250 139 316

Cedar Creek near DeSoto logFCB = 1.641logTBY-0.121 .84 .53 1.85 26 FCB 4–32,000 5,957 230 9,299

TBY 4–905 160 48 238

Indian Creek at State Line Road logFCB = 1.00logTBY+1.75 .67 .611 1.99 25 FCB 10–88,000 17,200 11,000 21,400

TBY 2–1,010 237 168 279

Kill Creek at 95th Street logFCB = 1.38logTBY+0.442 .77 .602 2.00 27 FCB 1–43,000 8,950 5,500 11,600

TBY 2–1,230 270 140 326

Mill Creek at Johnson Drive logFCB = 1.36logTBY+0.422 .80 .646 2.12 25 FCB 2–39,000 9,830 1,400 13,500

E. Coli bacteria (ECB), colonies per 100 milliliters

Blue River at Kenneth Road logECB = 1.38logTBY+0.287 .74 .661 2.15 21 ECB 2–32,000 6,630 1,500 9,950

TBY 3–1,270 240 109 311

Cedar Creek near DeSoto logECB = 1.54logTBY-0.0563 .86 .445 1.59 23 ECB 7–21,000 4,120 1,300 5,950

TBY 6–905 180 68 246

Indian Creek at State Line Road logECB = 1.02logTBY+1.58 .71 .570 1.85 25 ECB 10–32,000 11,300 8,700 11,100

TBY 2–1,010 237 168 279

Kill Creek at 95th Street logECB = 1.29logTBY+0.524 .79 .533 1.76 27 ECB 2–26,000 6,190 4,300 7,360

TBY 2–1,230 270 140 326

Mill Creek at Johnson Drive logECB = 1.23logTBY+0.508 .83 .526 1.74 25 ECB 2–22,000 4,990 360 7,270

TBY 2–1,100 269 91 363

Sites combined logECB = 1.28logTBY+0.602 .74 .624 2.67 121 ECB 2–32,000 6,630 2,400 8,730

TBY 2–1,270 239 110 305
38 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 8. Regression models and summary statistics for estimating concentrations and densities of selected constituents in water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete samples; mg/L, milligrams per liter; μg/L, micrograms per liter; ( ), number of values in sample set that were less than laboratory reporting level; log, refers to log10; SC, specific conductance, in microsiemens per centimeter at 25 degrees Celsius; Q, streamflow, in cubic feet per second (ft3/s); WT, water temperature in degrees Celsius (°C); TBY, turbidity, in formazin nephelometric units (FNUs); --, not applicable; <, less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias cor- rection factor (Duan, 1983) Discrete samples

n

Range of values in 

variable 

measurements

Mean Median Standard deviation

Enterococci bacteria (ENT), colonies per 100 milliliters

Blue River at Kenneth Road logENT = 1.73logTBY+0.392 0.88 0.512 1.79 21 ENT 215–380,000 65,900 11,000 113,000

TBY 3–1,270 240 109 311

Cedar Creek near DeSoto logENT = 1.79logTBY+0.170 .90 .446 1.71 25 ENT 18–110,000 22,300 3,500 31,800

TBY 4–905 166 50 241

Indian Creek at State Line Road logENT = 1.31logTBY+1.57 .81 .547 1.95 25 ENT 63–250,000 59,000 41,000 68,900

TBY 2–1,010 237 168 279

Kill Creek at 95th Street logENT = 1.44logTBY+1.07 .83 .529 1.69 27 ENT 39–440,000 57,700 31,000 92,700

TBY 2–1,230 270 140 326

Mill Creek at Johnson Drive logENT = 1.40logTBY+0.750 .80 .668 1.94 26 ENT 24–300,000 40,900 2,250 80,800

TBY 2–1,100 270 100 355
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 39

Regression models shown in table 9 demonstrate the 

statistical relations between suspended-sediment concentration 

and constituents often associated with particulates. Although 

strong relations exist for total suspended sediment and some 

indicator bacteria, relations with unfiltered (total) nutrients 

are weaker except at the Blue River site, and to a lesser extent 

the Kill Creek site, where nonpoint-source agricultural runoff 

is the primary source of nutrients. The trapping effects of 

impoundments may interfere with relations between sediment and nutrients in the Cedar Creek watershed. Nutrients 

originating from WWTFs at the Indian Creek site may result 

in poor relations with sediment at that site. These statistical relations have potential implications for implementation 

of BMPs demonstrating that if sediment concentrations are 

decreased, concentrations of sediment-associated constituents 

such as suspended solids, some nutrients, and bacteria also 

may decrease.

Graphs comparing the five site-specific models for 

suspended sediment, chloride, and E. coli indicator bacteria 

are shown in figure 14 and discussed in the relevant sections below. The 90-percent prediction intervals shown in 

figure 14 were calculated using a model with data from 

all sites combined; most of the model estimates fall within 

these boundaries.

Regression-Estimated Constituents

Suspended Sediment and Total Suspended 

Solids

Sediment in the water can reduce light penetration, 

smother benthic habitats, clog gill structures in fish, reduce 

photosynthesis, and interfere with water-treatment equipment 

(Devlin and McVay, 2001). Suspended sediment, particularly 

sediment composed of fine material (silt and clay), gives water 

a muddy appearance and provides attachment sites allowing 

accumulation and transport of nutrients, pesticides, and indicator bacteria (Jordan and Stamer, 1995). Sediment originates 

primarily from geology and surface soils, channel bank erosion, and streambed sediment re-suspended during stormflow. 

KDHE narrative criteria for suspended sediment state that 

artificial sources shall not interfere with aquatic life. Artificial 

sources include sources that result from human activities and 

may be minimized by construction of control structures, modification of operating practices, or restraint of activities (Kansas 

Department of Health and Environment, 2005).

Urbanization affects sediment supply and transport differently during construction and post-construction phases, as 

summarized by Paul and Meyer (2001). During the construction phases, erosion of exposed soils leads to larger sediment 

loads (Leopold, 1968). This effect intensifies in more sloped 

watersheds and generally occurs during a few large floods 

(Wolman, 1967). The increase in sediment supply leads to 

bed aggradation, and stream depths may decrease resulting 

in decreased channel capacity, larger floods, and overbank 

sediment deposition (Wolman, 1967). The aggradation phase 

is followed by an erosional phase, during which channel erosion is the largest source of sediment. Increases in impervious 

surface area substantially increase the frequency or volume 

of bankfull floods leading to a general deepening (incision) 

and widening of the channel (Booth, 1990). After incision, 

channels migrate laterally and bank erosion begins (Trimble, 

1997). In developed urban streams, the majority of sediment 

being transported originates from channel erosion rather than 

hillside erosion (Trimble, 1997).

Suspended-sediment concentration (SSC) and total 

suspended solids (TSS) are the two terms typically used to 

quantify concentrations of suspended solid-phase material 

in surface water. Although the terms are sometimes used 

interchangeably, the laboratory analytical methods differ 

and may produce considerably different results, particularly 

when samples contain sand-sized material (Gray and others, 

2000). The SSC method is preferred for quantifying solids in 

natural water samples because it has been found to be more 

reliable than the TSS method, which was originally designed 

for analysis of wastewater samples (Gray and others, 2000). 

However, TSS is sometimes used in regulatory applications 

such as TMDLs and NPDES permits. For example, the Mill 

Creek TMDL for biological impairment (Kansas Department 

of Health and Environment, 2007) identifies large sediment 

load and particularly TSS as a cause of biological impairment. 

The TMDL establishes a goal of 35 percent reduction in average TSS concentrations during the biologically active season. 

Although regression models were developed for both SSC and 

TSS (table 8), more emphasis is placed on the SSC models in 

this report.

Regression models for SSC (table 8) were among those 

with the least uncertainty, as indicated by R2 values equal to or 

larger than 0.95, RMSE values less than about 0.2, and evenly 

distributed residual plots (not shown). All SSC models used 

turbidity as the only explanatory variable. The regression lines 

are similar when compared between sites (fig. 14A) although 

the Mill Creek model has a slightly smaller slope than the 

other models indicating that sources of suspended sediment 

and turbidity might differ slightly from other sites. Different sources of sediment likely are caused by construction in 

urbanizing parts of the Mill Creek watershed. The models 

were developed using suspended-sediment concentrations in 

discrete samples ranging from less than 10 mg/L to greater 

than 2,000 mg/L at each site with a maximum of 4,170 mg/L 

at the Blue River site (table 8). In-stream turbidity in regression models ranged from about 5 FNUs to greater than 

1,000 FNUs at all sites except Cedar which had a maximum of 

905 FNUs (table 8).

Continuous estimates of suspended-sediment concentration in 2005–06 ranged from a minimum of less than 

3 mg/L at all sites, to a maximum of 4,600 mg/L at the 

Cedar Creek site in 2005 and the Blue River site in 2006 

(table 10). The other sites may have had suspended-sediment concentrations as large as Cedar Creek, but 
40 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 9. Regression models and statistics for estimating concentrations of selected constituents using suspended-sediment concentration in discrete samples from water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006. [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete sampes; SSC, suspended-sediment concetration; mg/L, milligrams per liter; --, not applicable; < less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias correction factor (Duan, 1983) Discrete sample results

n Range in response variable Range in SSC (mg/L) Mean Median Standard deviation

Total suspended solids (TSS), mg/L

Blue River at Kenneth Road logTSS = 1.01logSSC-0.102 0.98 0.1109 1.03 19 TSS 3–4,470 -- 571 240 1,010

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto logTSS = 1.04logSSC-0.134 .99 .0872 1.02 20 TSS 3–1,690 -- 410 183 532

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road logTSS = 0.912logSSC+0.176 .99 .0948 1.02 22 TSS 5–2,880 -- 582 285 795

-- SSC 2–3,530 711 299 992

Kill Creek at 95th Street logTSS = 1.03logSSC-0.175 .95 .1945 1.07 24 TSS 3–3,380 -- 637 261 881

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive logTSS = 0.989logSSC+0.0221 .99 .1129 1.04 21 TSS 4–2,780 -- 582 231 814

-- SSC 4–2,890 685 251 828

Combined logTSS = 0.989logSSC+0.0739 .97 .1359 1.07 106 TSS 3–4,470 -- 582 231 814

-- SSC 2–4,170 645 257 887

Total nitrogen (TN), mg/L

Blue River at Kenneth Road logTN = 0.330logSSC-0.451 .84 .0155 1.04 19 TN 0.59–8.75 -- 2.45 2.12 1.84

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto SSC not a significant 

explanatory variable

-- -- -- -- TN 1.37–9.20 -- 3.01 2.54 1.70

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road logTN = -0.121logSSC+0.936 .34 .0304 1.08 22 TN 2.30–12.5 -- 5.22 4.24 2.69

-- SSC 2–3,530 711 299 992

Kill Creek at 95th Street logTN = 0.360logSSC-0.577 .73 .0308 1.08 24 TN 0.45–7.31 -- 2.48 2.02 1.75

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive SSC not a significant 

explanatory variable

-- -- -- -- TN 0.68–10.9 -- 3.74 2.74 2.61

-- SSC 4–2,890 685 251 828

Combined logTN = 0.106logSSC+0.193 .09 .0834 1.27 106 TN 0.45–12.5 -- 3.39 2.83 2.37

-- SSC 2–4,170 645 257 887
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 41

Table 9. Regression models and statistics for estimating concentrations of selected constituents using suspended-sediment concentration in discrete samples from water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued[R2, coefficient of determination; RMSE, root mean square error; n, number of discrete sampes; SSC, suspended-sediment concetration; mg/L, milligrams per liter; --, not applicable; < less than]

Monitoring site 

(fig. 1) Regression model R2 RMSE

Bias 

correction 

factor (Duan, 

1983)

Discrete sample results

n Range in response variable Range in SSC (mg/L) Mean Median Standard deviation

Total phosphorus (TP), mg/L

Blue River at Kenneth Road logTP = 0.48logSSC-1.55 0.92 0.0144 1.04 19 TP 0.06–2.45 -- 0.52 0.38 0.54

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto SSC not a significant 

explanatory variable

-- -- -- -- TP 0.20–2.43 -- .69 .56 .51

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road SSC not a significant 

explanatory variable

-- -- -- -- TP 0.54–2.96 -- 1.19 1.00 .67

-- SSC2–3,530 711 299 992

Kill Creek at 95th Street logTP = 0.387logSSC-1.30 .63 .0550 1.14 24 TP 0.09–2.14 -- .60 .40 .50

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive logTP = 0.212logSSC-0.649 .37 .0670 1.18 21 TP 0.22–2.38 -- .89 .63 .66

-- SSC 4–2,890 685 251 828

Combined logTP = 0.181logSSC-0.652 .18 .108 1.36 106 TP 0.06–2.96 -- .78 .64 .62

-- SSC 2–4,170 645 257 887

Escherichia coli (E. coli) bacteria (ECB), colonies per 100 milliliters

Blue River at Kenneth Road logECB = 1.21logSSC+0.393 .71 .6566 2.03 19 ECB 2–32,000 -- 7,510 3,400 12,100

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto logECB = 1.27logSSC+0.199 .83 .4788 1.63 20 ECB 5–2,100 -- 4,720 1,900 6,160

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road logECB = 0.832logSSC+1.76 .58 .5785 1.83 22 ECB 10–32,000 -- 12,800 12,500 11,100

-- SSC 2–3,530 711 299 992

Kill Creek at 95th Street logECB = 0.984logSSC+0.983 .69 .5182 1.85 24 ECB 46–26,000 -- 6960 6,050 7460

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive logECB = 1.22logSSC+0.334 .88 .4425 1.48 20 ECB 2–22,000 -- 6,220 2,050 7,670

-- SSC 4–2,890 620 216 850

Combined logECB = 1.09logSSC+0.779 .71 .607 2.48 105 ECB 2–7,900 -- 8,940 4,200 12,500

SSC 2–4,170 632 236 891
42 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 9. Regression models and statistics for estimating concentrations of selected constituents using suspended-sediment concentration in discrete samples from water at five water-quality monitoring sites in Johnson County, northeast Kansas, October 2002–January 2006.—Continued [R2, coefficient of determination; RMSE, root mean square error; n, number of discrete sampes; SSC, suspended-sediment concetration; mg/L, milligrams per liter; --, not applicable; < less than] Monitoring site (fig. 1) Regression model R2 RMSE Bias correction factor (Duan, 1983) Discrete sample results

n Range in response variable Range in SSC (mg/L) Mean Median Standard deviation

Fecal coliform bacteria (ECB), colonies per 100 milliliters

Blue River at Kenneth Road logFCB = 1.09logSSC+0.802 0.71 0.5995 1.99 19 FCB 9–26,000 -- 7,420 4,000 8,660

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto logFCB = 1.28logSSC+0.342 .79 .5549 1.86 20 FCB 14–32,000 -- 7,730 3,900 9,970

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road logFCB = 0.819logSSC+1.94 .66 .6063 1.85 23 FCB 10–88,000 -- 19,400 13,500 21,900

-- SSC 2–3,530 711 299 992

Kill Creek at 95th Street logFCB = 1.03logSSC+0.998 .69 .5505 2.04 24 FCB 24–43,000 -- 10,100 6,400 11,900

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive logFCB = 1.31logSSC+0.304 .84 .5533 1.88 21 FCB 2–39,000 -- 11,700 5,100 14,000

-- SSC 4–2,890 624 234 828

Combined logFCB = 1.09logSSC+0.918 .70 .6155 2.39 106 FCB 2–88,000 -- 11,400 5,450 14,600

-- SSC 2–4,170 633 244 887

Enterococci bacteria (ECB), colonies per 100 milliliters

Blue River at Kenneth Road logENT = 1.47logSSC+0.669 .85 .5327 1.92 19 ENT 27–380,000 -- 75,700 18,000 115,000

-- SSC 7–4,170 627 384 977

Cedar Creek near DeSoto logENT = 1.44logSSC+0.586 .88 .4398 1.80 20 ENT 28–110,000 -- 27,800 22,000 33,400

-- SSC 4–2,060 437 202 564

Indian Creek at State Line Road logENT = 1.07logSSC+1.79 .76 .6157 2.29 22 ENT 63–250,000 -- 67,000 43,500 69,700

-- SSC 2–3,530 711 299 992

Kill Creek at 95th Street logENT = 1.31logSSC+1.02 .79 .5413 1.86 24 ENT 39–440,000 -- 64,900 39,000 96,100

-- SSC 7–3,690 736 288 1,020

Mill Creek at Johnson Drive logENT = 1.30logSSC+0.846 .87 .4864 1.51 21 ENT 47–300,000 -- 50,700 14,000 87,400

-- SSC 4–2,890 624 234 828

Combined logENT = 1.29logSSC+0.104 .81 .5468 2.15 106 ENT 27–440,000 -- 57,400 29,500 84,900

-- SSC 2–4,170 633 244 887
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 43

Figure 14. Comparison of explanatory (x-axis) and response (y-axis) variables for 

selected water-quality constituent regression models for (A) suspended-sediment 

concentration, (B) chloride, and (C) Escherichia coli bacteria.

logECB = 1.38logTBY + 0.287

 R2 = 0.74

logECB = 1.54logTBY - 0.0563

 R2

 = 0.86

logECB = 1.02logTBY + 1.58

 R2

 = 0.71

logECB = 1.29logTBY + 0.524

 R2

 = 0.79

logECB = 1.23logTBY + 0.508

 R2 = 0.83

logECB = 1.28logTBY + 0.602

 R2

 = 0.74 

1

10

100

1,000

10,000

100,000

1,000,000

1 10 100 1,000 10,000

Turbidity (TBY), in formazin nephelometric units (YSI 6136 sensor)

Escherichia coli bacteria, in colonies per 100 milliliters

(C) Escherichia coli bacteria (ECB)

logCl = 1.53logSC - 2.43

 R2 = 0.94

logCl = 1.76logSC - 3.18

 R2

 = 0.92

logCl = 1.26logSC - 1.93

 R2 = 0.73

logCl = 1.21logSC - 1.91

 R2

 = 0.66

logCl = 1.48logSC - 2.30

 R2

 = 0.92

logCl = 1.63logSC - 2.82

 R2

 = 0.87 

1

10

100

1,000

10,000

100 1,000 10,000

Specific conductance (SC), in microsiemens per centimeter

Chloride concentration, in milligrams per liter

(B) Chloride (Cl)

logSSC = 1.16logTBY - 0.140

 R2 = 0.96

logSSC = 1.17logTBY - 0.116

 R2

 = 0.97

logSSC = 1.10logTBY + 0.068

 R2

 = 0.96

logSSC = 1.16logTBY - 0.111

 R2

 = 0.98

logSSC = 1.02logTBY + 0.144

 R2

 = 0.95

log SSC = 1.12logTBY - 0.020

 R2

 = 0.96

1

10

100

1,000

10,000

1 10 100 1,000 10,000

Turbidity (TBY), in formazin nephelometric units (YSI 6136 sensor)

Suspended-sediment concentration, in milligrams per liter

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Sites combined

90-percent prediction interval

(A) Suspended-sediment concentration (SSC)

Monitoring sites (fig.1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Sites combined

90-percent prediction interval

Monitoring sites (fig.1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Sites combined

90-percent prediction interval

Monitoring sites (fig.1)
44 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006. Calendar year and monitoring site (fig. 1) Number of values Sample standard deviation Concentration or density at indicated frequency of exceedance, in percent Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum Suspended-sediment concentration, in milligrams per liter 2005 Blue River at Kenneth Road 8,724 120 1.0 1.4 2.5 4.0 6.9 10 23 62 130 540 2,700 Cedar Creek near DeSoto 8,654 200 1.0 1.0 1.8 2.6 5.3 9.2 16 37 87 650 4,600 Indian Creek at State Line Road 8,723 160 1.0 1.0 1.1 1.9 4.0 7.9 18 72 190 840 3,000 Kill Creek at 95th Street 8,692 130 1.0 1.0 1.0 1.1 5.2 9.8 17 45 110 640 3,900 Mill Creek at Johnson Drive 8,573 190 2.8 3.1 4.8 6.4 9.7 19 42 110 210 1,100 2,200 2006 Blue River at Kenneth Road 8,760 160 1.3 2.2 3.1 3.8 5.1 8.5 15 36 82 520 4,600 Cedar Creek near DeSoto 8,760 92 1.0 1.3 2.0 2.7 4.7 8.8 15 24 40 200 4,300 Indian Creek at State Line Road 8,315 140 1.0 1.7 2.6 3.1 4.6 8.4 18 59 130 610 3,100 Kill Creek at 95th Street 8,526 85 1.0 1.0 1.1 2.1 5.7 12 20 34 59 170 3,200 Mill Creek at Johnson Drive 8,718 110 1.0 3.0 3.8 4.8 7.2 13 21 44 89 370 3,900 Total suspended solids, in milligrams per liter 2005 Blue River at Kenneth Road 8,724 96 0.70 1.3 2.3 3.6 6.1 9.3 20 54 110 450 2,200 Cedar Creek near DeSoto 8,654 210 .13 .58 1.4 2.0 4.2 7.5 14 32 78 640 5,000 Indian Creek at State Line Road 8,723 130 .20 1.0 1.8 2.8 5.6 10 22 77 190 720 2,300 Kill Creek at 95th Street 8,692 110 .06 .06 .28 1.1 4.9 9.1 16 41 97 540 3,200 Mill Creek at Johnson Drive 8,573 180 3.5 3.9 5.8 7.7 12 22 47 120 220 1,100 2,100 2006 Blue River at Kenneth Road 8,760 130 1.2 2.0 2.8 3.4 4.6 7.5 13 31 71 430 3,700 Cedar Creek near DeSoto 8,760 96 .58 1.0 1.5 2.1 3.7 7.1 12 20 35 190 4,600 Indian Creek at State Line Road 8,315 120 1.2 2.6 3.8 4.4 6.3 11 22 64 130 540 2,400 Kill Creek at 95th Street 8,526 71 .06 .52 1.1 2.0 5.4 11 19 31 53 150 2,600

Mill Creek at Johnson Drive 8,718 110 .20 3.7 4.7 5.8 8.7 15 25 49 97 380 3,700
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 45

Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued

Calendar year and monitoring 

site (fig. 1)

Number of 

values

Sample 

standard 

deviation

Concentration or density at indicated frequency of exceedance, in percent

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum

Dissolved solids, in milligrams per liter

2005

Blue River at Kenneth Road 8,760 6.8 22 36 44 48 53 58 61 63 65 72 76Cedar Creek near DeSoto 8,656 62 130 230 310 340 390 440 470 490 500 540 580Indian Creek at State Line Road 8,723 220 140 210 310 380 490 550 600 840 1,100 1,400 1,700Kill Creek at 95th Street 8,760 39 130 210 260 290 330 350 370 380 390 390 400Mill Creek at Johnson Drive 8,654 140 170 240 310 360 450 530 570 710 780 950 1,200

2006

Blue River at Kenneth Road 8,760 42 120 220 280 310 340 370 390 410 410 420 430Cedar Creek near DeSoto 8,760 70 110 230 320 380 430 480 510 530 540 610 710Indian Creek at State Line Road 8,760 220 130 220 320 380 490 570 650 730 820 1,600 2,400Kill Creek at 95th Street 8,691 34 170 250 290 310 330 360 380 380 390 410 410Mill Creek at Johnson Drive 8,760 160 170 250 310 360 410 520 600 650 760 1,200 1,600

Calcium, dissolved, in milligrams per liter

2005

Blue River at Kenneth Road 8,760 12 20 40 52 60 68 78 83 87 90 100 110Cedar Creek near DeSoto 8,656 7.8 37 54 65 69 76 82 85 88 89 93 98Indian Creek at State Line Road 8,723 19 20 28 38 45 56 62 66 87 110 140 150Kill Creek at 95th Street 8,760 11 20 37 50 58 68 76 81 84 86 88 90Mill Creek at Johnson Drive 8,654 16 31 42 51 57 68 79 83 99 110 130 150

2006

Blue River at Kenneth Road 8,760 13 17 40 56 64 75 83 90 95 96 98 100Cedar Creek near DeSoto 8,760 8.6 33 54 66 74 81 86 90 92 94 100 110Indian Creek at State Line Road 8,760 19 18 29 39 46 56 63 71 78 86 150 210Kill Creek at 95th Street 8,691 9.9 28 48 57 62 68 78 83 85 88 92 93Mill Creek at Johnson Drive 8,760 19 31 42 50 57 64 77 87 92 110 150 200
46 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued Calendar year and monitoring site (fig. 1) Number of values Sample standard deviation Concentration or density at indicated frequency of exceedance, in percent Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum Magnesium, dissolved, in milligrams per liter 2005 Blue River at Kenneth Road 8,760 1.5 2.4 4.8 6.3 7.3 8.3 9.6 10 11 11 13 14 Cedar Creek near DeSoto 8,656 1.3 3.4 5.7 7.4 8.1 9.3 10 11 11 11 12 13 Indian Creek at State Line Road 8,723 5.5 2.7 4.2 6.4 8.0 11 12 13 19 25 35 41 Kill Creek at 95th Street 8,760 1.4 2.7 5.0 6.7 7.8 9.1 10 11 11 11 12 12 Mill Creek at Johnson Drive 8,654 2.9 4.1 5.8 7.3 8.4 10 12 13 16 17 21 26 2006 Blue River at Kenneth Road 8,760 1.6 2.0 4.8 6.9 7.8 9.2 10 11 12 12 12 12 Cedar Creek near DeSoto 8,760 1.5 2.9 5.7 7.6 8.9 10 11 12 12 12 14 16 Indian Creek at State Line Road 8,760 5.7 2.4 4.5 6.6 8.2 11 13 15 17 19 40 61 Kill Creek at 95th Street 8,691 1.3 3.9 6.4 7.6 8.3 9.1 10 11 11 12 12 12 Mill Creek at Johnson Drive 8,760 3.5 4.1 5.8 7.1 8.3 9.5 12 14 15 17 25 35 Sodium, dissolved, in milligrams per liter 2005 Blue River at Kenneth Road 8,760 4.1 4.9 11 15 17 20 23 25 27 28 32 36 Cedar Creek near DeSoto 8,656 13 6.6 19 30 36 47 57 63 68 70 80 92 Indian Creek at State Line Road 8,723 60 14 24 40 54 78 93 110 170 240 360 440 Kill Creek at 95th Street 8,760 4.5 4.9 11 16 19 23 26 29 30 31 32 33 Mill Creek at Johnson Drive 8,654 32 13 23 33 41 58 76 84 120 140 190 270 2006 Blue River at Kenneth Road 8,760 4.2 4.2 11 16 19 22 25 28 29 30 30 31 Cedar Creek near DeSoto 8,760 15 5.0 19 32 43 55 66 73 78 82 100 130 Indian Creek at State Line Road 8,760 65 11 26 43 56 78 97 120 140 160 430 730 Kill Creek at 95th Street 8,691 4.1 7.8 15 18 20 23 27 29 30 31 33 34

Mill Creek at Johnson Drive 8,760 42 13 23 32 41 51 73 92 100 130 250 440
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 47

Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued

Calendar year and monitoring 

site (fig. 1)

Number of 

values

Sample 

standard 

deviation

Concentration or density at indicated frequency of exceedance, in percent

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum

Sulfate, dissolved, in milligrams per liter

2005

Blue River at Kenneth Road 8,760 8.4 8.8 21 28 33 39 46 50 53 55 65 72Cedar Creek near DeSoto 8,656 17 17 38 56 64 79 92 99 110 110 120 130Indian Creek at State Line Road 8,723 57 15 26 43 57 81 95 110 170 230 340 420Kill Creek at 95th Street 8,760 8.6 12 24 33 40 48 54 58 60 62 64 65Mill Creek at Johnson Drive 8,654 31 21 34 47 56 74 92 100 130 150 200 270

2006

Blue River at Kenneth Road 8,760 8.7 7.4 21 31 36 44 50 55 58 59 61 63Cedar Creek near DeSoto 8,760 20 13 38 58 74 90 100 110 120 120 140 180Indian Creek at State Line Road 8,760 61 13 28 45 58 80 99 120 140 160 410 680Kill Creek at 95th Street 8,691 7.7 18 32 39 43 47 55 59 61 63 67 68Mill Creek at Johnson Drive 8,760 39 21 34 45 56 67 89 110 120 150 250 390

Chloride, dissolved, in milligrams per liter

2005

Blue River at Kenneth Road 8,760 6.8 7.6 17 24 28 32 38 41 43 45 53 59Cedar Creek near DeSoto 8,656 18 7.0 22 38 46 61 76 84 92 95 110 130Indian Creek at State Line Road 8,723 111 16 30 54 75 120 140 160 270 400 640 820Kill Creek at 95th Street 8,760 5.1 6.1 13 18 22 27 30 33 34 35 36 37Mill Creek at Johnson Drive 8,654 56 18 33 50 64 92 120 140 200 230 320 490

2006

Blue River at Kenneth Road 8,760 7.1 6.4 17 26 30 36 41 45 48 49 50 52Cedar Creek near DeSoto 8,760 22 5.2 22 40 56 73 89 99 110 110 140 190Indian Creek at State Line Road 8,760 127 13 32 57 77 110 140 180 220 260 790 1,500Kill Creek at 95th Street 8,691 4.6 9.4 17 22 24 27 31 34 35 36 38 39Mill Creek at Johnson Drive 8,760 76 18 34 48 64 81 120 150 170 220 450 800
48 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued Calendar year and monitoring site (fig. 1) Number of values Sample standard deviation Concentration or density at indicated frequency of exceedance, in percent Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum Nitrogen, total, in milligrams per liter 2005 Blue River at Kenneth Road 8,760 0.23 0.83 0.84 0.90 0.97 1.1 1.2 1.4 1.6 1.7 2.0 2.6 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,723 1.85 2.30 3.06 4.35 5.11 6.40 7.48 9.14 10.1 10.4 10.7 11.6 Kill Creek at 95th Street 8,692 .47 .10 .10 .17 .29 .51 .64 .78 1.1 1.5 2.9 5.6 Mill Creek at Johnson Drive 8,573 .41 1.3 1.3 1.3 1.4 1.6 2.2 3.2 3.6 3.8 4.9 13 2006 Blue River at Kenneth Road 8,760 .19 .61 .68 .85 .89 .99 1.1 1.2 1.3 1.4 1.7 2.3 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,315 1.74 2.48 3.33 4.43 5.26 6.37 7.29 8.70 9.70 10.3 11.2 12.6 Kill Creek at 95th Street 8,526 .33 .10 .22 .29 .37 .52 .68 .83 1.0 1.2 1.8 5.2 Mill Creek at Johnson Drive 8,718 .89 1.3 1.3 1.3 1.3 1.5 2.2 3.2 3.6 3.6 3.7 23.0 Phosphorus, total, in milligrams per liter 2005 Blue River at Kenneth Road 8,760 .07 .16 .16 .16 .16 .16 .17 .18 .21 .26 .51 1.6 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,723 .29 .26 .47 .74 .95 1.2 1.5 1.6 1.6 1.7 1.8 1.9 Kill Creek at 95th Street 8,692 .10 .23 .23 .23 .23 .24 .25 .26 .29 .35 .77 2.8 Mill Creek at Johnson Drive 8,573 .20 .29 .29 .30 .30 .34 .43 .55 .61 .65 1.1 3.3 2006 Blue River at Kenneth Road 8,760 .09 .15 .16 .16 .16 .16 .16 .17 .19 .22 .49 2.4 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,315 .27 .25 .55 .84 1.1 1.4 1.5 1.6 1.7 1.7 1.8 2.0 Kill Creek at 95th Street 8,526 .06 .20 .20 .20 .20 .21 .21 .22 .24 .26 .34 2.0

Mill Creek at Johnson Drive 8,718 .21 .29 .29 .29 .30 .33 .43 .54 .59 .60 .63 14
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 49

Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued

Calendar year and monitoring 

site (fig. 1)

Number of 

values

Sample 

standard 

deviation

Concentration or density at indicated frequency of exceedance, in percent

Minimum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum

Escherichia coli bacteria, in colonies per 100 milliliters

2005

Blue River at Kenneth Road 8,724 668 1.1 2.3 4.6 8.0 15 25 64 210 510 2,700 18,000Cedar Creek near DeSoto 8,654 4,234 1.0 1.4 4.1 6.5 17 34 73 210 650 9,100 120,000Indian Creek at State Line Road 8,723 5,290 6.7 35 63 99 200 380 810 2,900 7,200 28,000 90,000Kill Creek at 95th Street 8,692 2,116 3.7 3.7 5.9 13 48 94 180 510 1,400 9,600 70,000Mill Creek at Johnson Drive 8,573 2,550 12 13 22 31 50 110 290 880 2,000 14,000 32,000

2006

Blue River at Kenneth Road 8,760 1,040 2.1 3.9 6.0 7.5 11 19 38 110 290 2,600 34,000Cedar Creek near DeSoto 8,760 1,894 1.4 2.6 4.7 6.9 14 32 64 120 240 2,000 110,000Indian Creek at State Line Road 8,315 4,617 42 92 140 160 230 400 800 2,400 5,000 21,000 94,000Kill Creek at 95th Street 8,526 1,405 0.1 3.7 8 17 52 110 210 370 690 2,200 57,000Mill Creek at Johnson Drive 8,718 1,560 1.0 12 16 22 35 69 130 300 710 3,900 65,000

Fecal coliform bacteria, in colonies per 100 milliliters

2005

Blue River at Kenneth Road 8,724 2,737 9.9 19 36 60 110 170 400 1,200 2,600 12,000 69,000Cedar Creek near DeSoto 8,654 8,797 1.0 1.4 4.4 7.2 20 43 95 300 1,000 16,000 260,000Indian Creek at State Line Road 8,723 7,494 11 56 100 160 310 580 1,200 4,300 10,000 40,000 120,000Kill Creek at 95th Street 8,692 3,639 1.0 1.0 1.6 8.0 51 110 210 660 1,900 15,000 130,000Mill Creek at Johnson Drive 8,573 6,194 12 14 25 37 64 150 440 1,500 3,700 32,000 83,000

2006

Blue River at Kenneth Road 8,760 3,961 18 31 46 56 78 130 250 640 1,600 11,000 120,000Cedar Creek near DeSoto 8,760 3,890 1.4 2.7 5.1 7.7 17 40 83 160 340 3,200 230,000Indian Creek at State Line Road 8,315 6,533 67 140 210 250 350 620 1,200 3,600 7,400 30,000 130,000Kill Creek at 95th Street 8,526 2,399 1.0 3.4 8.0 18 57 130 250 470 900 3,100 100,000Mill Creek at Johnson Drive 8,718 3,938 1.0 13 18 25 43 91 180 470 1,200 8,000 180,000
50 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 10. Regression-estimated concentrations for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued Calendar year and monitoring site (fig. 1) Number of values Sample standard deviation Concentration or density at indicated frequency of exceedance, in percent Mini- mum 1 per- centile 5 per- centile 10 per- centile 25 per- centile 50 per- centile (median) 75 per- centile 90 per- centile 95 per- centile 99 per- centile Maximum Enterococci bacteria, in colonies per 100 milliliters 2005 Blue River at Kenneth Road 8,724 26,440 4.4 11 26 53 120 220 720 3,200 9,800 80,000 900,000 Cedar Creek near DeSoto 8,654 45,110 1.0 2.5 8.8 15 45 100 250 870 3,200 70,000 1,400,000 Indian Creek at State Line Road 8,723 33,410 3.6 29 63 110 280 630 1,700 8,700 28,000 160,000 720,000 Kill Creek at 95th Street 8,692 19,260 1.0 1.0 5.3 29 200 440 890 2,900 8,600 77,000 710,000 Mill Creek at Johnson Drive 8,573 16,530 25 29 51 77 140 340 1,000 3,600 9,100 85,000 230,000 2006 Blue River at Kenneth Road 8,760 50,310 10 22 37 49 77 160 370 1,400 4,800 75,000 2,000,000 Cedar Creek near DeSoto 8,760 19,710 2.5 5.2 10 16 38 98 220 450 990 12,000 1,200,000 Indian Creek at State Line Road 8,315 29,810 37 100 170 200 330 680 1,700 6,800 18,000 110,000 760,000 Kill Creek at 95th Street 8,526 12,810 1.0 12 29 66 220 550 1,100 2,000 4,000 14,000 560,000 Mill Creek at Johnson Drive 8,718 10,670 1.0 27 37 51 90 200 400 1,100 2,800 20,000 500,000
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 51

different maximum measurement on turbidity sensors may 

have prevented larger readings. The largest median concentration for any year occurred at the Mill Creek site in 

2005 (19 mg/L) where the median was nearly double that 

of the other four sites (7.9–10 mg/L). Suspended-sediment 

concentration was nearly always largest at the Mill Creek 

site (fig. 15). The Mill Creek watershed is undergoing rapid 

development that likely is contributing to larger sustained 

sediment concentrations. About 70 percent of the time, the 

smallest sediment concentration occurred at the Indian Creek 

site (fig. 15), in part because most of the streamflow at this site 

originated from treated WWTF discharge just upstream (Lee 

and others, 2005).

Estimated annual suspended sediment loads and yields 

were largest at the Indian Creek site, and annual loads were 

smallest at the Kill Creek site (table 11, fig. 16). Most of the 

time between January 2005 and December 2006, the hourly 

sediment load was larger at the Indian and Mill Creek sites 

(fig. 17, table 12), which carry larger streamflow volumes. The 

estimated annual sediment load at all sites was larger in 2005 

than in 2006 by 33 (Indian Creek) to 750 percent (Kill Creek; 

table 11). Annual differences can be attributed to differences 

in precipitation and streamflow both of which were larger in 

2005 (table 6).

At least 90 percent of the total annual load in 2005–06 

at all sites occurred during less than 2 percent of the time 

(fig. 18), generally corresponding with the largest streamflow. 

The streamflow that was exceeded less than 2 percent of the 

time at the monitoring sites ranged from about 250 ft3/s at the 

Cedar and Kill Creek sites to about 1,000 ft3/s at the Indian 

Creek site (fig. 4). Therefore, management practices designed 

to control sediment during typical streamflows rather than 

infrequent large streamflow will have minimal effect on total 

annual loads. During the 3- to 4-year period of record for the 

five monitoring sites, streamflow has only slightly exceeded 

the estimated 2-year peak streamflow (Perry and others, 2004) 

at all sites except the Cedar and Kill Creek sites where streamflow has not exceeded the 2-year peak since monitoring began 

(fig. 19). Therefore, sediment load contributions when the 

2-year streamflow is exceeded have not been well documented 

but are expected to be even larger than loads measured during 

this study period. Without continuous water-quality monitoring and load estimation, variations in loads corresponding 

with rapidly changing streamflow conditions would not be 

documented. Long-term monitoring makes it possible to assess 

both changes in streamflow and changes in sediment concentrations and loads and may make it possible to relate changes 

to implemented BMPs.

Individual runoff occurrences were examined for relative 

sediment load contributions and hysteresis patterns to improve 

characterization of sediment transport within each watershed. In June 2005, a single runoff period on the Blue River 

that included a peak streamflow of 9,840 ft3/s (between the 

estimated 2-year peak streamflow of 6,570 ft3/s and the 5-year 

Figure 15. Duration curves for estimated suspended-sediment concentration at five water-quality 

monitoring sites in Johnson County, Kansas, March 2004–December 2006.

0

1

10

100

1,000

10,000

0 10 20 30 40 50 60 70 80 90 100

Suspended-sediment concentration, in milligrams per liter

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
52 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06. [mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day] Calendar year and monitoring site (fig. 1) Num- ber of values Mean daily con- centration (mg/L) Esti- mated mean daily load (tons per day) Esti- mated annual load (tons) Total seasonal loads, in tons, and mean daily load (in parentheses), in tons per day Esti- mated yield [(ton/ mi2)/yr] November 1–February 28 March 1–July 31 August 1–October 31 Suspended-sediment concentration 2005 6893100 Blue River at Kenneth Road 8,724 36.8 84.5 30,800 5,350 (44.6) 18,900 (124) 6,530 (71.0) 469 6892495 Cedar Creek near DeSoto 8,654 36.2 75.8 27,100 4,650 (39.6) 14,300 (93.4) 8,180 (93.4) 463 6893390 Indian Creek at State Line Road 8,723 45.7 132 47,800 5,300 (44.2) 24,100 (161) 18,400 (200) 758 6892360 Kill Creek at 95th Street 8,692 34.5 67.5 24,500 3,160 (27.0) 11,500 (75.0) 9,830 (107) 504 6892513 Mill Creek at Johnson Drive 8,573 63.5 121 43,300 6,590 (57.7) 15,900 (105) 20,800 (226) 736 2006 6893100 Blue River at Kenneth Road 8,760 31.6 41.6 15,200 738 (6.15) 6,960 (45.5) 7,490 (81.4) 231 6892495 Cedar Creek near DeSoto 8,760 19.0 14.3 5,190 216 (1.83) 2,880 (18.8) 2,090 (22.8) 88.7 6893390 Indian Creek at State Line Road 8,315 37.5 104 35,900 948 (8.78) 19,600 (131) 15,400 (172) 569 6892360 Kill Creek at 95th Street 8,526 22.5 8.14 2,880 215 (1.90) 2,480 (16.2) 186 (2.07) 59.3 6892513 Mill Creek at Johnson Drive 8,718 30.5 29.8 10,800 696 (5.89) 4,710 (30.8) 5,400 (58.7) 184 Total suspended solids 2005 6893100 Blue River at Kenneth Road 8,724 31.3 69.8 25,400 4,460 (37.1) 15,500 (103) 5,390 (58.6) 387 6892495 Cedar Creek near DeSoto 8,654 34.6 78.1 28,000 4,730 (40.3) 14,800 (96.6) 8,450 (96.5) 479 6893390 Indian Creek at State Line Road 8,723 43.9 111 40,200 4,810 (40.0) 20,000 (134) 15,400 (168) 637 6892360 Kill Creek at 95th Street 8,692 30.2 57.0 20,700 2,710 (23.2) 9,640 (63.0) 8,310 (90.3) 426 6892513 Mill Creek at Johnson Drive 8,573 66.5 119 42,400 6,540 (57.3) 15,600 (103) 20,300 (221) 721 2006 6893100 Blue River at Kenneth Road 8,760 26.7 34.2 12,500 616 (5.15) 5,760 (37.6) 6,090 (66.2) 190 6892495 Cedar Creek near DeSoto 8,760 17.1 14.5 5,260 205 (1.74) 2,920 (19.1) 2,140 (23.3) 89.9

6893390 Indian Creek at State Line Road 8,315 37.2 85.9 29,700 948 (8.77) 15,900 (107) 12,900 (144) 4716892360 Kill Creek at 95th Street 8,526 20.1 6.86 2,430 181 (1.64) 2,090 (13.6) 159 (1.77) 50.06892513 Mill Creek at Johnson Drive 8,718 33.0 29.2 10,600 710 (6.01) 4,630 (30.3) 5,270 (57.3) 180
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 53

Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued[mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day]

Calendar year and monitoring site 

(fig. 1)

Number of 

values

Mean 

daily concentration 

(mg/L)

Estimated 

mean 

daily 

load 

(tons per 

day)

Estimated 

annual 

load (tons)

Total seasonal loads, in tons, and mean daily load (in parentheses), 

in tons per day Estimated 

yield 

[(ton/

mi2)/yr]

November 1–February 28 March 1–July 31 August 1–October 31

Dissolved solids

2005

6893100 Blue River at Kenneth Road 8,760 345 46.8 17,100 7,120 (59.3) 6,530 (42.7) 3,430 (37.3) 2606892495 Cedar Creek near DeSoto 8,656 425 49.2 17,600 7,140 (60.9) 6,710 (43.9) 3,770 (43.0) 3016893390 Indian Creek at State Line Road 8,723 583 114 41,200 18,200 (152) 13,200 (88.3) 9,820 (107) 6536892360 Kill Creek at 95th Street 8,760 343 32.4 11,800 4,240 (35.3) 4,700 (30.7) 2,900 (31.5) 2436892513 Mill Creek at Johnson Drive 8,654 526 70.1 25,300 10,600 (87.9) 8,650 (56.5) 6,070 (69.3) 430

2006

6893100 Blue River at Kenneth Road 8,760 362 14.5 5,290 1,370 (11.4) 2,900 (19.0) 1,020 (11.1) 80.56892495 Cedar Creek near DeSoto 8,760 463 19.8 7,170 1,890 (16.0) 3,800 (24.9) 1,480 (16.1) 1236893390 Indian Creek at State Line Road 8,760 583 77.5 28,300 9,860 (82.2) 11,200 (73.3) 7,220 (78.5) 4486892360 Kill Creek at 95th Street 8,691 350 8.06 2,910 640 (5.55) 2,060 (13.5) 206 (2.24) 59.96892513 Mill Creek at Johnson Drive 8,760 522 30.5 11,200 3,700 (30.8) 4,740 (31.0) 2,710 (29.5) 190

Calcium, dissolved

2005

6893100 Blue River at Kenneth Road 8,760 75.2 9.34 3,400 1,480 (12.4) 1,260 (8.26) 660 (7.18) 51.86892495 Cedar Creek near DeSoto 8,656 79.9 10.0 3,590 1,370 (11.7) 1,390 (9.09) 828 (9.44) 61.46893390 Indian Creek at State Line Road 8,723 63.9 13.0 4,690 1,910 (15.9) 1,580 (10.6) 1,200 (13.0) 74.36892360 Kill Creek at 95th Street 8,760 73.2 6.25 2,280 857 (7.14) 905 (5.91) 521 (5.66) 46.96892513 Mill Creek at Johnson Drive 8,654 77.3 10.7 3,870 1,520 (12.7) 1,370 (8.96) 980 (11.2) 65.8

2006

6893100 Blue River at Kenneth Road 8,760 80.7 3.00 1,100 302 (2.52) 608 (3.97) 186 (2.02) 16.76892495 Cedar Creek near DeSoto 8,760 84.3 3.79 1,380 344 (2.92) 733 (4.79) 300 (3.26) 23.66893390 Indian Creek at State Line Road 8,760 64.0 8.91 3,250 1,040 (8.69) 1,320 (8.63) 887 (9.64) 51.56892360 Kill Creek at 95th Street 8,691 75.2 1.67 604 138 (1.20) 424 (2.77) 41.5 (.45) 12.46892513 Mill Creek at Johnson Drive 8,760 76.7 4.65 1,700 527 (4.40) 727 (4.75) 442 (4.81) 28.9
54 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued [mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day] Calendar year and monitoring site (fig. 1) Num- ber of values Mean daily con- centration (mg/L) Esti- mated mean daily load (tons per day) Esti- mated annual load (tons) Total seasonal loads, in tons, and mean daily load (in parentheses), in tons per day Esti- mated yield [(ton/ mi2)/yr] November 1–February 28 March 1–July 31 August 1–October 31 Magnesium, dissolved 2005 6893100 Blue River at Kenneth Road 8,760 9.21 1.14 416 181 (1.51) 154 (1.01) 80.5 (0.87) 6.32 6892495 Cedar Creek near DeSoto 8,656 9.88 1.17 420 167 (1.42) 161 (1.05) 92.0 (1.05) 7.18 6893390 Indian Creek at State Line Road 8,723 13.1 2.51 906 420 (3.50) 280 (1.87) 206 (2.24) 14.4 6892360 Kill Creek at 95th Street 8,760 9.74 .84 306 115 (.95) 121 (.79) 70.3 (.76) 6.30 6892513 Mill Creek at Johnson Drive 8,654 12.0 1.61 581 238 (1.99) 201 (1.31) 142 (1.62) 9.88 2006 6893100 Blue River at Kenneth Road 8,760 9.88 .37 134 37.0 (.31) 74.2 (.49) 22.6 (.25) 2.04 6892495 Cedar Creek near DeSoto 8,760 10.7 .46 168 43.5 (.37) 89.2 (.58) 35.3 (.38) 2.87 6893390 Indian Creek at State Line Road 8,760 13.1 1.69 618 226 (1.88) 241 (1.57) 151 (1.64) 9.79 6892360 Kill Creek at 95th Street 8,691 10.0 .22 80.6 18.4 (.16) 56.6 (.37) 5.55 (.06) 1.66 6892513 Mill Creek at Johnson Drive 8,760 11.9 .70 256 83.3 (.69) 109 (.71) 63.5 (.69) 4.35 Sodium, dissolved 2005 6893100 Blue River at Kenneth Road 8,760 22.5 2.68 979 434 (3.62) 359 (2.34) 186 (2.02) 14.9 6892495 Cedar Creek near DeSoto 8,656 54.4 5.50 1,970 881 (7.51) 725 (4.74) 362 (4.13) 33.7 6893390 Indian Creek at State Line Road 8,723 104 19.1 6,900 3,630 (30.3) 1,910 (12.8) 1,360 (14.8) 109 6892360 Kill Creek at 95th Street 8,760 25.2 1.99 725 282 (2.35) 287 (1.87) 156 (1.70) 14.9 6892513 Mill Creek at Johnson Drive 8,654 76.6 9.23 3,330 1,630 (13.6) 1,020 (6.67) 677 (7.73) 56.6 2006 6893100 Blue River at Kenneth Road 8,760 24.3 .88 320 90.6 (.75) 178 (1.17) 51.3 (.56) 4.87 6892495 Cedar Creek near DeSoto 8,760 63.1 2.47 896 258 (2.19) 470 (3.07) 168 (1.82) 15.3 6893390 Indian Creek at State Line Road 8,760 104 12.7 4,620 1,940 (16.2) 1,690 (11.1) 993 (10.8) 73.2

6892360 Kill Creek at 95th Street 8,691 26.0 .56 204 48.1 (.42) 142 (.93) 13.6 (.15) 4.206892513 Mill Creek at Johnson Drive 8,760 76.5 4.10 1,500 594 (4.95) 610 (3.99) 293 (3.19) 25.5
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 55

Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued[mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day]

Calendar year and monitoring site 

(fig. 1)

Number of 

values

Mean 

daily concentration 

(mg/L)

Estimated 

mean 

daily 

load 

(tons per 

day)

Estimated 

annual 

load (tons)

Total seasonal loads, in tons, and mean daily load (in parentheses), 

in tons per day Estimated 

yield 

[(ton/

mi2)/yr]

November 1–February 28 March 1–July 31 August 1–October 31

Sulfate, dissolved

2005

6893100 Blue River at Kenneth Road 8,760 44.2 5.17 1,890 845 (7.04) 688 (4.50) 356 (3.87) 28.86892495 Cedar Creek near DeSoto 8,656 88.1 9.48 3,390 1,450 (12.4) 1,270 (8.30) 672 (7.66) 57.96893390 Indian Creek at State Line Road 8,723 105 19.5 7,050 3,620 (30.1) 2,000 (13.4) 1,430 (15.6) 1126892360 Kill Creek at 95th Street 8,760 51.7 4.24 1,550 591 (4.93) 612 (4.00) 343 (3.73) 31.96892513 Mill Creek at Johnson Drive 8,654 92.1 11.6 4,180 1,900 (15.9) 1,360 (8.87) 924 (10.6) 71.1

2006

6893100 Blue River at Kenneth Road 8,760 48.0 1.71 623 178 (1.49) 348 (2.27) 97.2 (1.06) 9.486892495 Cedar Creek near DeSoto 8,760 99.0 4.04 1,460 405 (3.43) 773 (5.05) 287 (3.12) 25.06893390 Indian Creek at State Line Road 8,760 105 13.0 4,750 1,940 (16.1) 1,760 (11.5) 1,050 (11.4) 75.36892360 Kill Creek at 95th Street 8,691 53.3 1.17 422 98.1 (.85) 295 (1.93) 28.6 (.31) 8.686892513 Mill Creek at Johnson Drive 8,760 91.6 5.11 1,860 680 (5.66) 778 (5.09) 407 (4.42) 31.6

Chloride, dissolved

2005

6893100 Blue River at Kenneth Road 8,760 36.7 4.34 1,580 705 (5.88) 578 (3.78) 299 (3.25) 24.06892495 Cedar Creek near DeSoto 8,656 72.2 7.09 2,540 1,160 (9.90) 931 (6.08) 450 (5.13) 43.46893390 Indian Creek at State Line Road 8,723 162 29.1 10,500 5,960 (49.6) 2,680 (18.0) 1,870 (20.3) 1666892360 Kill Creek at 95th Street 8,760 29.1 2.33 851 329 (2.74) 337 (2.20) 185 (2.02) 17.56892513 Mill Creek at Johnson Drive 8,654 125 14.8 5,340 2,690 (22.4) 1,600 (10.4) 1,050 (12.0) 90.8

2006

6893100 Blue River at Kenneth Road 8,760 39.8 1.43 520 148 (1.23) 290 (1.90) 82.1 (.89) 7.916892495 Cedar Creek near DeSoto 8,760 85.0 3.26 1,180 348 (2.95) 618 (4.04) 217 (2.36) 20.26893390 Indian Creek at State Line Road 8,760 161 19.1 6,970 3,180 (26.5) 2,430 (15.9) 1,360 (14.8) 1106892360 Kill Creek at 95th Street 8,691 30.0 .65 236 55.4 (.48) 165 (1.08) 15.9 (.17) 4.866892513 Mill Creek at Johnson Drive 8,760 125 6.61 2,410 990 (8.25) 970 (6.34) 451 (4.90) 41.0
56 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued [mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day] Calendar year and monitoring site (fig. 1) Num- ber of values Mean daily con- centration (mg/L) Esti- mated mean daily load (tons per day) Esti- mated a nnual load (tons) Total seasonal loads, in tons, and mean daily load (in parentheses), in tons per day Esti- mated yield [(ton/ mi2)/yr] November 1–February 28 March 1–July 31 August 1–October 31 Nitrogen, total 2005 6893100 Blue River at Kenneth Road 8,760 1.26 0.33 121 40.4 (0.34) 55.1 (0.36) 25.8 (0.28) 1.84 6892495 Cedar Creek near DeSoto Estimated values not available 6893390 Indian Creek at State Line Road 8,723 7.59 1.39 503 157 (1.31) 223 (1.46) 123 (1.34) 7.98 6892360 Kill Creek at 95th Street 8,692 .72 .28 101 21.8 (.19) 44.3 (.29) 35.2 (.38) 2.08 6892513 Mill Creek at Johnson Drive 8,573 2.41 .69 247 88.3 (.77) 72.5 (.48) 86.2 (.94) 4.20 2006 6893100 Blue River at Kenneth Road 8,760 1.12 .09 31.1 5.54 (.05) 15.5 (.10) 10.1 (.11) .47 6892495 Cedar Creek near DeSoto Estimated values not available. 6893390 Indian Creek at State Line Road 8,315 7.44 1.03 358 87.90 (.73) 174 (1.14) 96 (1.04) 5.67 6892360 Kill Creek at 95th Street 8,526 .71 .04 14.0 1.82 (.02) 11.0 (.07) 1.20 (.01) .29 6892513 Mill Creek at Johnson Drive 8,718 2.36 .24 87.1 22.6 (.19) 33.3 (.22) 31.2 (.34) 1.48 Phosphorous, total 2005 6893100 Blue River at Kenneth Road 8,724 .18 .08 28.5 7.11 (.06) 15.2 (.10) 6.15 (.07) .43 6892495 Cedar Creek near DeSoto Estimated values not available. 6893390 Indian Creek at State Line Road 8,674 1.36 .21 77.0 23.6 (.20) 30.5 (.20) 22.9 (.25) 1.22 6892360 Kill Creek at 95th Street 8,692 .23 .07 26.2 5.26 (.05) 11.5 (.08) 9.39 (.10) .54 6892513 Mill Creek at Johnson Drive 8,573 .46 .18 62.7 17.4 (.15) 20.0 (.13) 25.3 (.28) 1.07 2006 6893100 Blue River at Kenneth Road 8,760 .18 .03 11.2 1.05 (.01) 5.34 (.03) 4.78 (.05) .17 6892495 Cedar Creek near DeSoto Estimated values not available. 6893390 Indian Creek at State Line Road 8,315 1.45 .17 59.8 15.1 (.14) 26.5 (.18) 18.2 (.20) .95

6892360 Kill Creek at 95th Street 8,526 .22 .01 3.80 .51 (0) 3.01 (.02) .28 (0) .086892513 Mill Creek at Johnson Drive 8,718 .44 .06 23.2 3.95 (.03) 9.61 (.06) 9.62 (.10) .39
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 57

Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued[mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day]

Calendar year and monitoring site

(fig. 1)

Number 

of values

Mean daily 

concentration 

(col/100mL)

Estimated 

mean 

daily 

load 

(billion 

col/day)

Estimated 

annual 

load 

(billion 

col)

Total seasonal loads (mean daily load) in billion colonies

Estimated 

yield 

[(billion 

col/mi2)/yr)

November 1–February 28 March 1–July 31 August 1–October 31

Escherichia coli bacteria

2005

6893100 Blue River at Kenneth Road 8,724 149 4,310 1,560,000 240,000 (2,000) 1,000,000 (6,620) 322,000 (3,500) 23,7006892495 Cedar Creek near DeSoto 8,654 466 13,100 4,690,000 758,000 (6,470) 2,510,000 (16,400) 1,420,000 (16,200) 80,2006893390 Indian Creek at State Line Road 8,723 1,700 39,800 14,400,000 1,690,000 (14,100) 7,120,000 (47,700) 5,570,000 (60,500) 228,0006892360 Kill Creek at 95th Street 8,692 461 9,720 3,540,000 422,000 (3,520) 1,670,000 (10,900) 1,450,000 (15,800) 73,0006892513 Mill Creek at Johnson Drive 8,573 646 14,500 5,180,000 743,000 (6,510) 1,920,000 (12,700) 2,520,000 (27,400) 88,100

2006

6893100 Blue River at Kenneth Road 8,760 140 2,430 889,000 35,000 (292) 408,000 (2,670) 446,000 (4,840) 13,5006892495 Cedar Creek near DeSoto 8,760 166 2,260 820,000 21,800 (185) 437,000 (2,860) 361,000 (3,920) 14,0006893390 Indian Creek at State Line Road 8,315 1,410 30,700 10,600,000 327,000 (3,030) 5,710,000 (38,300) 4,600,000 (51,400) 168,0006892360 Kill Creek at 95th Street 8,526 271 1,140 418,000 27,900 (229) 364,000 (2,320) 25,600 (278) 8,6806892513 Mill Creek at Johnson Drive 8,718 266 3,590 1,300,000 68,600 (580) 576,000 (3,770) 659,000 (7,160) 22,100

Fecal coliform bacteria

2005

6893100 Blue River at Kenneth Road 8,724 737 17,900 6,490,000 1,070,000 (8,910) 4,060,000 (26,800) 1,360,000 (14,800) 98,8006892495 Cedar Creek near DeSoto 8,654 873 26,300 9,400,000 1,510,000 (12,900) 5,030,000 (32,900) 2,860,000 (32,600) 161,0006893390 Indian Creek at State Line Road 8,723 2,450 56,300 20,300,000 2,430,000 (20,300) 10,100,000 (67,600) 7,810,000 (84,900) 322,0006892360 Kill Creek at 95th Street 8,692 679 16,200 5,870,000 658,000 (5,620) 2,780,000 (18,100) 2,430,000 (26,400) 121,0006892513 Mill Creek at Johnson Drive 8,573 1,340 34,700 12,400,000 1,710,000 (15,000) 4,610,000 (30,500) 6,080,000 (66,100) 211,000

2006

6893100 Blue River at Kenneth Road 8,760 654 9,350 3,410,000 151,000 (1,260) 1,570,000 (10,300) 1,690,000 (18,400) 51,9006892495 Cedar Creek near DeSoto 8,760 283 4,430 1,610,000 37,700 (319) 844,000 (5,520) 727,000 (7,900) 27,5006893390 Indian Creek at State Line Road 8,315 2,080 43,500 15,100,000 480,000 (4,440) 8,060,000 (54,100) 6,520,000 (72,900) 239,0006892360 Kill Creek at 95th Street 8,526 373 1,950 691,000 42,200 (381) 608,000 (3,970) 40,800 (454) 14,2006892513 Mill Creek at Johnson Drive 8,718 512 8,700 3,170,000 146,000 (1,230) 1,410,000 (9,200) 1,610,000 (17,500) 53,900
58 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 11. Estimated concentrations, loads, and yields for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, 2005–06.—Continued [mg/L, milligrams per liter; ton/mi2/yr, tons per square mile per year; col/100 mL, colonies per 100 milliliters; billion col/day, billion colonies per day] Calendar year and monitoring site (fig. 1) Number of values Mean daily concen- tration (col/100mL) Esti- mated mean daily load (billion col/day) Esti- mated annual load (billion col) Total seasonal loads (mean daily load) in billion colonies Esti- mated yield [(billion col/mi2)/yr) November 1–February 28 March 1–July 31 August 1–October 31 Enterococci bacteria 2005 6893100 Blue River at Kenneth Road 8,724 3,800 162,000 59,100,000 7,380,000 (61,500) 40,100,000 (264,000) 11,600,000 (126,000) 900,000 6892495 Cedar Creek near DeSoto 8,654 3,960 128,000 45,800,000 7,350,000 (62,700) 24,500,000 (160,000) 14,000,000 (160,000) 783,000 6893390 Indian Creek at State Line Road 8,723 7,250 235,000 84,900,000 8,200,000 (68,300) 43,800,000 (293,000) 32,900,000 (357,000) 1,350,000 6892360 Kill Creek at 95th Street 8,692 3,320 84,600 30,700,000 3,310,000 (28,300) 14,600,000 (95,300) 12,800,000 (139,000) 632,000 6892513 Mill Creek at Johnson Drive 8,573 3,400 92,200 33,000,000 4,500,000 (39,400) 12,300,000 (81,200) 16,200,000 (176,000) 561,000 2006 6893100 Blue River at Kenneth Road 8,760 4,450 114,000 41,500,000 1,200,000 (9,930) 18,900,000 (123,000) 21,400,000 (232,000) 632,000 6892495 Cedar Creek near DeSoto 8,760 1,150 21,100 7,640,000 150,000 (1,270) 3,900,000 (25,500) 3,590,000 (39,000) 131,000 6893390 Indian Creek at State Line Road 8,315 5,690 191,000 66,300,000 1,220,000 (11,300) 37,300,000 (250,000) 27,800,000 (310,000) 1,050,000 6892360 Kill Creek at 95th Street 8,526 1,740 10,200 3,620,000 210,000 (1,900) 3,200,000 (20,900) 209,000 (2,320) 74,500 6892513 Mill Creek at Johnson Drive 8,718 1,270 23,200 8,440,000 371,000 (3,140) 3,770,000 (24,700) 4,300,000 (46,700) 144,000
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 59

Figure 16. Estimated annual loads and yields for suspended sediment, chloride, and Escherichia coli bacteria at five water-quality 

monitoring sites in Johnson County, Kansas, 2005–06.

0

100

200

300

400

500

600

700

800

Estimated suspended-sediment yield,

in tons per square mile per year

0

20

40

60

80

100

120

140

160

180

Estimated chloride yield,

in tons per square mile per year

0

50,000

Monitoring sites (fig. 1)

100,000

150,000

200,000

250,000

Estimated Escherichia coli bacteria yield,

in billion colonies per square mile per year

0

10,000

20,000

30,000

40,000

50,000

60,000

Blue River

at Kenneth

Road

Cedar Creek

near DeSoto

Indian Creek

at State Line

Road

Kill Creek

at 95th

Street

Mill Creek

at Johnson

Drive

Blue River

at Kenneth

Road

Cedar Creek

near DeSoto

Indian Creek

at State Line

Road

Kill Creek

at 95th

Street

Mill Creek

at Johnson

Drive

Estimated suspendedsediment load, in tons

2005

2006

2005

2006

2005

2006

2005

2006

2005

2006

2005

2006

0

2,000

4,000

6,000

8,000

10,000

12,000

Estimated chloride load, in tons

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

16,000,000

Estimated Escherichia coli bacteria

load, in billion colonies
60 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

estimated peak streamflow of 11,600 ft3/s) on the Blue River 

lasted about 3 days but contributed more than 50 percent of 

the total annual suspended-sediment load (fig. 20, table 13). 

Therefore, about 50 percent of the 2005 sediment load at the 

Blue River site occurred during less than 1 percent of the time. 

Similarly, a June 2005 storm runoff lasting about 4 days on 

Kill Creek contributed 42 percent of the annual sediment load 

(table 13). The associated peak streamflow was 5,820 ft3/s, 

which was less than the estimated 2-year streamflow of 

6,470 ft3/s. Approximately 80 percent of the total annual 

sediment load in 2005 at the Kill Creek site occurred during four periods of runoff totaling about 10 days. A 2.4-day 

runoff at the Indian Creek site in June 2005 contributed about 

30 percent of the total annual suspended-sediment load while 

reaching a peak streamflow of 10,500 ft3/s, approximately 

equal to the estimated 5-year peak streamflow. Five of 10 runoff periods at the Indian Creek site that exceeded 1,000 ft3

/s 

in 2005 showed single-line (Type 1) hysteresis characteristics, 

indicative of unlimited sediment supplies during runoff conditions. However, large peak streamflows at the Indian Creek 

site did not result in turbidity conditions or sediment loads 

as large as those that occurred at the other sites under similar 

streamflow conditions.

Dissolved Solids, Chloride, and Other Major Ions

Dissolved solids in surface water primarily consist of 

the major ions calcium, magnesium, sodium, potassium, 

bicarbonate, sulfate, and chloride. These ions originate from 

the decomposition of soils and rocks (Hem, 1992). In addition, 

dissolved solids in stream water can increase as a result of 

sewage, industrial effluents, agricultural runoff, urban runoff, 

and atmospheric deposition (Maidment, 1993; Wetzel, 2001). 

The relative amount of different ions in surface water varies 

depending on the sources. Dissolved solids are used as an 

indicator for suitability of water for drinking, irrigation, and 

industrial use (Maidment, 1993).

All of the regression models for dissolved solids and 

major ions included specific conductance as the only explanatory variable (table 8), which is reasonable because specific 

conductance is an indirect measure of the ionized substances 

in water. Uncertainty in the regression models for dissolved 

solids (which is a measure of all the major ions combined) 

was minimal, as indicated by high R2 values ranging from 

0.88 to 0.98, and low RMSE values of 0.0523 or less (table 

8). The ranges of specific conductance and dissolved solids 

at the Blue River and Kill Creek sites were smaller than the 

other sites (because of the larger percentage of nonurban 

land use upstream from the sites) which contributed to more 

uncertainty in the models. Uncertainty in models for individual ions varied. R2

 values ranged from 0.66 for chloride at 

the Kill Creek site to 0.97 for sodium at the Indian Creek site. 

RMSE values ranged from 0.0423 for magnesium at the Blue 

River site to 0.168 for chloride at the Kill Creek site (table 8). 

A much smaller portion of dissolved solids at nonurban sites 

comes from chloride compared to urban sites.

Figure 17. Duration curves for estimated suspended-sediment load at five water-quality monitoring 

sites in Johnson County, Kansas, January 2005–December 2006.

0

0.001

0.01

0.1

1.0

10

100

1,000

10,000

100,000

0 10 20 30 40 50 60 70 80 90 100

Estimated suspended-sediment load, in tons per hour 

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 61

Table 12. Regression-estimated loads for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.

Calendar year and 

monitoring site 

(fig. 1)

Number of 

values

Sample 

standard 

deviation

Load or density at indicated frequency of exceedance, in percent

Minimum 1 percentile 5 percentile 10 percentile 25 percentile 50 percentile 75 percentile 90 percentile 95 percentile 99 percentile Maximum

Suspended-sediment load, in tons per day

2005

Blue River at Kenneth Road 8,724 1,253 0.002 0.007 0.017 0.031 0.110 0.340 1.60 13.0 70.0 1,300 45,000Cedar Creek near DeSoto 8,588 1,059 .020 .028 .049 .074 .160 .350 1.20 6.10 32.0 1,100 39,000Indian Creek at State Line Road 8,674 1,362 .037 .053 .076 .120 .290 .670 2.80 21.0 140 2,680 43,000Kill Creek at 95th Street 8,692 876 .005 .013 .018 .030 .083 .200 .720 6.30 38.0 1,360 33,000Mill Creek at Johnson Drive 8,573 1,277 .062 .089 .150 .200 .390 .860 3.70 24.0 139 2,600 45,000

2006

Blue River at Kenneth Road 8,760 807 .0002 .001 .006 .013 .035 .100 .320 2.00 8.10 220 41,000Cedar Creek near DeSoto 8,710 293 .023 .033 .044 .053 .081 .170 .330 1.10 3.10 74.4 13,000Indian Creek at State Line Road 8,315 1,460 .032 .086 .140 .180 .280 .600 1.70 14.0 64.0 870 46,000Kill Creek at 95th Street 8,483 181 .005 .010 .014 .016 .029 .065 .170 .610 2.40 31.0 10,000Mill Creek at Johnson Drive 8,718 520 .012 .046 .071 .093 .150 .290 .860 3.80 14.0 290 31,000

Total suspended solids, in tons per day

2005

Blue River at Kenneth Road 8,724 1,028 .002 .006 .015 .028 .998 .303 1.36 11.3 59.2 1,090 36,700Cedar Creek near DeSoto 8,588 1,120 .003 .016 .037 .057 .124 .281 .955 5.21 28.4 1,090 41,800Indian Creek at State Line Road 8,674 1,099 .011 .055 .115 .184 .406 .877 3.35 22.4 142 2,290 34,000Kill Creek at 95th Street 8,692 730 .001 .002 .006 .022 .078 .183 .670 5.73 33.9 1,150 26,900Mill Creek at Johnson Drive 8,573 1,232 .077 .110 .176 .240 .457 .996 4.10 25.4 141 2,540 42,900

2006

Blue River at Kenneth Road 8,760 658 .0001 .001 .005 .012 .031 .089 .284 1.72 6.99 185 33,400Cedar Creek near DeSoto 8,710 307 .014 .025 .034 .041 .064 .137 .278 .903 2.67 69.6 14,100Indian Creek at State Line Road 8,315 1,168 .041 .130 .199 .257 .386 .783 2.07 15.3 65.3 767 36,100Kill Creek at 95th Street 8,483 151 .001 .006 .011 .015 .027 .060 .161 .562 2.22 27.3 8,280Mill Creek at Johnson Drive 8,718 495 .004 .056 .087 .112 .180 .340 .989 4.23 15.4 300 29,100

Dissolved solids, in tons per day

2005

Blue River at Kenneth Road 8,760 154 .281 .361 .674 1.27 6.59 11.6 33.6 93.8 183 581 3,640Cedar Creek near DeSoto 8,590 125 3.00 3.73 6.58 8.28 11.2 17.8 38.3 84.6 160 718 2,230Indian Creek at State Line Road 8,674 255 17.9 23.9 28.6 30.9 36.2 46.8 86.2 206 380 1,270 4,000Kill Creek at 95th Street 8,760 112 .765 .828 1.46 3.17 5.46 9.41 20.2 53.5 110 483 2,610Mill Creek at Johnson Drive 8,654 168 5.63 6.79 10.7 12.8 16.9 26.9 54.7 127 258 864 3,310

2006

Blue River at Kenneth Road 8,760 60 .023 .055 .440 .687 1.74 5.86 10.9 22.8 40.9 140 1,380Cedar Creek near DeSoto 8,710 63 1.74 2.63 4.11 4.70 6.25 10.2 15.7 27.1 51.8 198 1,550Indian Creek at State Line Road 8,760 184 18.0 22.4 26.3 28.7 32.8 40.1 54.5 126 236 632 3,990Kill Creek at 95th Street 8,648 32 .184 .332 .494 .567 .947 3.68 6.25 13.0 24.7 83.1 991Mill Creek at Johnson Drive 8,760 80 2.57 3.42 4.34 5.86 9.68 14.7 24.6 49.3 86.2 344 1,630
62 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 12. Regression-estimated loads for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006. —Continued Calendar year and monitoring site (fig. 1) Num- ber of values Sample standard deviation Load or density at indicated frequency of exceedance, in percent Minimum 1 percentile 5 percentile 10 percentile 25 percentile 50 percentile 75 percentile 90 percentile 95 percentile 99 percentile Maximum Calcium, dissolved, in tons per day 2005 Blue River at Kenneth Road 8,760 26.5 0.057 0.075 0.143 0.270 1.47 2.56 7.38 19.8 36.7 110 571 Cedar Creek near DeSoto 8,590 28.9 .575 .720 1.24 1.56 2.10 3.32 7.36 16.1 32.0 156 560 Indian Creek at State Line Road 8,674 30.9 2.02 2.70 3.22 3.48 4.03 5.27 9.70 22.5 41.2 150 563 Kill Creek at 95th Street 8,760 19.1 .164 .178 .310 .670 1.17 2.03 4.35 11.0 21.4 86.4 426 Mill Creek at Johnson Drive 8,654 27.6 .881 1.03 1.62 1.93 2.50 3.97 7.98 18.8 40.0 138 593 2006 Blue River at Kenneth Road 8,760 10.8 .005 .012 .101 .152 .381 1.32 2.41 5.02 8.84 28.4 258 Cedar Creek near DeSoto 8,710 13.3 .412 .573 .760 .866 1.13 1.83 2.87 5.02 9.78 40.6 307 Indian Creek at State Line Road 8,760 23.6 2.02 2.52 2.97 3.22 3.66 4.41 6.08 14.3 25.8 79.2 537 Kill Creek at 95th Street 8,648 5.99 .040 .071 .102 .118 .198 .795 1.37 2.77 5.32 17.2 179 Mill Creek at Johnson Drive 8,760 13.1 .404 .540 .670 .903 1.44 2.17 3.62 7.18 12.50 54.8 288 Magnesium, dissolved, in tons per day 2005 Blue River at Kenneth Road 8,760 3.22 .007 .009 .017 .033 .180 .313 .903 2.42 4.47 13.5 69.1 Cedar Creek near DeSoto 8,590 3.09 .070 .088 .153 .194 .261 .412 .892 1.98 3.79 17.4 56.8 Indian Creek at State Line Road 8,674 5.44 .395 .526 .630 .678 .799 1.03 1.89 4.70 8.64 27.1 84.5 Kill Creek at 95th Street 8,760 2.58 .022 .024 .041 .089 .156 .269 .579 1.47 2.87 11.7 58.0 Mill Creek at Johnson Drive 8,654 3.93 .130 .156 .244 .293 .385 .612 1.24 2.89 5.96 19.9 79.6 2006 Blue River at Kenneth Road 8,760 1.31 .001 .002 .012 .019 .047 .161 .295 .614 1.08 3.47 31.5 Cedar Creek near DeSoto 8,710 1.52 .044 .065 .095 .109 .144 .233 .361 .630 1.21 4.70 36.6 Indian Creek at State Line Road 8,760 3.81 .397 .494 .576 .631 .723 .892 1.20 2.77 5.31 13.6 90.2 Kill Creek at 95th Street 8,648 .805 .005 .009 .014 .016 .026 .106 .182 .369 .708 2.30 24.2 Mill Creek at Johnson Drive 8,760 1.88 .060 .079 .100 .135 .221 .336 .562 1.12 1.96 8.04 38.2 Sodium, dissolved, in tons per day 2005 Blue River at Kenneth Road 8,760 7.14 .016 .022 .042 .079 .443 .771 2.22 5.82 10.6 32.0 146 Cedar Creek near DeSoto 8,590 11.2 .357 .412 .779 1.04 1.44 2.28 4.87 10.5 18.3 64.2 158 Indian Creek at State Line Road 8,674 40.3 2.95 3.86 4.69 5.09 6.04 7.72 14.7 37.8 69.1 207 774 Kill Creek at 95th Street 8,760 5.45 .057 .061 .106 .227 .410 .706 1.50 3.63 6.89 25.9 117 Mill Creek at Johnson Drive 8,654 19.0 .674 .863 1.40 1.69 2.33 3.92 7.71 17.8 36.1 104 289 2006 Blue River at Kenneth Road 8,760 2.98 .002 .004 .030 .046 .114 .399 .729 1.50 2.31 8.41 74.3

Cedar Creek near DeSoto 8,710 6.52 .139 .249 .505 .635 .857 1.43 2.12 3.64 6.63 21.3 175Indian Creek at State Line Road 8,760 25.8 2.97 3.63 4.22 4.72 5.43 6.87 9.43 20.5 41.8 108 729Kill Creek at 95th Street 8,648 1.87 .014 .025 .035 .040 .067 .273 .481 .952 1.83 5.74 53.3Mill Creek at Johnson Drive 8,760 9.32 .302 .405 .541 .710 1.30 2.09 3.52 7.44 13.0 39.8 250
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 63

Table 12. Regression-estimated loads for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued

Calendar year and 

monitoring site 

(fig. 1)

Number of 

values

Sample 

standard 

deviation

Load or density at indicated frequency of exceedance, in percent

Minimum 1 percentile 5 percentile 10 percentile 25 percentile 50 percentile 75 percentile 90 percentile 95 percentile 99 percentile Maximum

Sulfate, dissolved, in tons per day

2005

Blue River at Kenneth Road 8,760 13.4 0.032 0.043 0.082 0.155 0.877 1.53 4.36 11.4 20.4 61.7 266Cedar Creek near DeSoto 8,590 21.4 .606 .736 1.32 1.71 2.34 3.69 7.89 17.3 31.0 121 342Indian Creek at State Line Road 8,674 41.1 3.03 3.99 4.82 5.22 6.20 7.91 15.0 38.1 70.7 210 763Kill Creek at 95th Street 8,760 12.2 .116 .125 .219 .472 .834 1.44 3.06 7.59 14.8 56.6 268Mill Creek at Johnson Drive 8,654 25.4 .894 1.12 1.79 2.13 2.89 4.70 9.38 21.9 43.5 136 427

2006

Blue River at Kenneth Road 8,760 5.66 .003 .007 .059 .090 .224 .791 1.44 2.95 5.12 16.4 143Cedar Creek near DeSoto 8,710 11.7 .284 .467 .841 .996 1.35 2.20 3.34 5.78 10.7 37.5 301Indian Creek at State Line Road 8,760 26.8 3.06 3.78 4.38 4.86 5.56 7.01 9.57 21.2 42.5 111 737Kill Creek at 95th Street 8,648 4.02 .028 .051 .072 .082 .138 .560 .976 1.95 3.76 12.0 117Mill Creek at Johnson Drive 8,760 12.4 .404 .534 .705 .940 1.64 2.55 4.25 8.86 15.8 54.6 294

Chloride, dissolved, in tons per day

2005

Blue River at Kenneth Road 8,760 11.3 .027 .036 .069 .129 .726 1.26 3.62 9.49 17.2 51.8 229Cedar Creek near DeSoto 8,590 13.8 .463 .531 1.02 1.38 1.91 3.02 6.47 13.9 23.7 78.7 182Indian Creek at State Line Road 8,674 62.8 4.10 5.58 6.89 7.57 8.98 11.5 22.6 57.2 104 309 1,310Kill Creek at 95th Street 8,760 6.53 .065 .071 .123 .264 .472 .812 1.73 4.23 8.08 30.6 141Mill Creek at Johnson Drive 8,654 29.9 1.05 1.33 2.19 2.70 3.75 6.35 12.4 29.2 57.2 163 476

2006

Blue River at Kenneth Road 8,760 4.77 .002 .006 .049 .074 .186 .654 1.19 2.46 4.25 13.7 120Cedar Creek near DeSoto 8,710 8.28 .164 .304 .651 .847 1.14 1.93 2.83 4.86 8.75 27.5 225Indian Creek at State Line Road 8,760 38.5 4.41 5.20 6.14 6.86 8.07 10.3 14.4 30.7 61.4 175 1,140Kill Creek at 95th Street 8,648 2.20 .016 .028 .040 .046 .078 .316 .553 1.10 2.11 6.69 63.4Mill Creek at Johnson Drive 8,760 14.7 .470 .626 .851 1.11 2.08 3.38 5.71 12.2 21.5 60.6 411

Nitrogen, total, in tons per day

2005

Blue River at Kenneth Road 8,760 2.18 .001 .001 .002 .004 .020 .040 .138 .454 1.13 5.02 68.2Cedar Creek near DeSoto Estimated values not available.Indian Creek at State Line Road 8,674 3.69 .195 .345 .396 .429 .515 .696 1.08 2.14 3.86 13.65 103Kill Creek at 95th Street 8,692 2.22 .001 .002 .002 .003 .007 .015 .037 .180 .540 6.17 57.3Mill Creek at Johnson Drive 8,573 4.41 .016 .021 .031 .040 .074 .117 .258 .687 1.79 11.7 141

2006

Blue River at Kenneth Road 8,760 .725 .0001 .0001 .001 .002 .005 .018 .035 .088 .183 .821 24.2Cedar Creek near DeSoto Estimated values not available.Indian Creek at State Line Road 8,315 2.97 .244 .308 .349 .371 .442 .563 .747 1.44 2.82 8.80 75.3Kill Creek at 95th Street 8,483 .461 .0003 .001 .001 .001 .002 .005 .010 .026 .072 .406 20.5Mill Creek at Johnson Drive 8,718 2.45 .010 .012 .016 .021 .037 .066 .120 .229 .448 2.59 159
64 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Table 12. Regression-estimated loads for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006. —Continued Calendar year and monitoring site (fig. 1) Num- ber of values Sample standard deviation Load or density at indicated frequency of exceedance, in percent Minimum 1 percentile 5 percentile 10 percentile 25 percentile 50 percentile 75 percentile 90 percentile 95 percentile 99 percentile Maximum Phosphorus, total, in tons per day 2005 Blue River at Kenneth Road 8,724 0.8223 0.000156 0.0001887 0.000327 0.0006479 0.00281 0.00544 0.017 0.05701 0.1566 1.24 27.2 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,674 .3572 .0649 .0772 .0871 .0907 .102 .121 .193 .327 .5948 1.725 7.24 Kill Creek at 95th Street 8,692 .6597 .000458 .0005154 .000934 .00189 .0032 .00544 .0125 .0432 .112 1.416 20.2 Mill Creek at Johnson Drive 8,573 1.433 .00356 .00464 .00681 .00867 .0143 .0221 .0467 .127 .3647 3.078 51.2 2006 Blue River at Kenneth Road 8,760 .4601 .0000102 .000025 .000192 .000301 .000798 .00255 .00488 .0119 .02715 .2258 21.3 Cedar Creek near DeSoto Estimated values not available. Indian Creek at State Line Road 8,315 .3179 .0593 .0709 .0805 .0838 .0942 .105 .143 .259 .441 1.21 7.32 Kill Creek at 95th Street 8,483 .1369 .000109 .000207 .000331 .000402 .000615 .00208 .00359 .008062 .0183 .08297 6.98 Mill Creek at Johnson Drive 8,718 1.174 .00214 .00258 .003464 .00459 .00764 .0122 .0212 .04357 .08744 .5453 78.4 Escherichia coli bacteria, in billion colonies per day 2005 Blue River at Kenneth Road 8,724 70,700 .029 .127 .339 .563 2.20 7.31 37.8 379 2,320 57,700 2,710,000 Cedar Creek near DeSoto 8,588 212,000 .188 .376 1.02 1.66 4.68 12.1 44.3 307 2,080 131,000 8,640,000 Indian Creek at State Line Road 8,674 394,000 11.7 24.5 44.3 64.7 137 291 1,130 7,690 49,300 818,000 12,200,000 Kill Creek at 95th Street 8,692 135,000 .170 .463 .903 2.21 7.04 16.8 66.4 630 4,200 186,000 5,440,000 Mill Creek at Johnson Drive 8,573 165,000 2.29 6.37 9.22 11.6 21.2 47.5 232 1,700 11,800 303,000 5,910,000 2006 Blue River at Kenneth Road 8,760 51,000 .003 .015 .107 .261 .713 1.97 7.12 53.9 261 9,610 2,800,000 Cedar Creek near DeSoto 8,710 56,000 .305 .662 .969 1.27 2.24 5.80 12.8 44.8 148 6,390 2,980,000 Indian Creek at State Line Road 8,315 420,000 13.0 41.6 64.0 83.0 125 257 688 5,200 22,500 269,000 13,000,000 Kill Creek at 95th Street 8,483 51,900 .088 .512 1.21 1.83 3.65 8.74 23.2 89.4 372 6,070 2,940,000 Mill Creek at Johnson Drive 8,718 72,400 .178 1.77 2.88 3.89 6.75 13.9 47.2 238 1,010 27,300 4,510,000 Fecal coliform bacteria, in billion colonies per day 2005 Blue River at Kenneth Road 8,724 277,000 .243 .918 2.37 4.14 15.6 49.6 238 2,170 12,300 264,000 10,300,000 Cedar Creek near DeSoto 8,588 441,000 .188 .377 1.10 1.85 5.54 15.0 56.8 435 3,170 233,000 18,400,000 Indian Creek at State Line Road 8,674 557,000 5.60 27.7 58.2 93.3 206 444 1,700 11,300 71,800 1,160,000 17,200,000 Kill Creek at 95th Street 8,692 27,800 .001 .390 .871 1.28 2.46 5.84 15.5 57.9 239 3,570 1,560,000 Mill Creek at Johnson Drive 8,573 412,000 2.48 3.69 6.90 10.6 23.8 64.9 351 2,860 22,100 699,000 15,000,000 2006 Blue River at Kenneth Road 8,760 188,000 .020 .112 .786 1.85 5.01 14.1 47.6 319 1,440 43,900 9,920,000

Cedar Creek near DeSoto 8,710 115,000 .306 .696 1.06 1.42 2.63 7.14 16.6 59.9 206 10,400 6,390,000Indian Creek at State Line Road 8,315 591,000 20.9 65.7 101 130 195 396 1,050 7,750 33,000 389,000 18,300,000Kill Creek at 95th Street 8,483 47,800 .088 .356 .875 1.36 2.80 6.71 18.0 70.4 296 5,080 2,720,000Mill Creek at Johnson Drive 8,718 191,000 .151 1.96 3.30 4.59 8.37 18.0 65.9 362 1,710 54,700 12,200,000
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 65

Table 12. Regression-estimated loads for selected water-quality constituents at five water-quality monitoring sites in Johnson County, northeast Kansas, January 2005–December 2006.—Continued

Calendar year and 

monitoring site 

(fig. 1)

Number of 

values

Sample 

standard 

deviation

Load or density at indicated frequency of exceedance, in percent

Minimum 1 percentile 5 percentile 10 percentile 25 percentile 50 percentile 75 percentile 90 percentile 95 percentile 99 percentile Maximum

Enterococci bacteria, in billion colonies per day

2005

Blue River at Kenneth Road 8,724 3,060,000 0.136 0.899 2.32 3.86 16.9 63.2 431 5,790 44,000 1,700,000 128,000,000Cedar Creek near DeSoto 8,588 2,250,000 .188 .681 2.20 3.93 12.7 37.2 149 1,250 10,200 977,000 97,100,000Indian Creek at State Line Road 8,674 2,600,000 1.78 14.8 37.1 66.7 183 480 2,360 21,700 187,000 4,510,000 83,800,000Kill Creek at 95th Street 8,692 1,260,000 .088 .233 .996 6.04 30.3 76.9 341 3,540 27,700 1,520,000 54,700,000Mill Creek at Johnson Drive 8,573 1,110,000 4.96 7.42 14.1 22 50.5 142 799 6,780 53,300 1,830,000 40,400,000

2006

Blue River at Kenneth Road 8,760 2,650,000 .015 .104 .752 1.87 5.58 15.1 65.8 673 4,280 259,000 161,000,000Cedar Creek near DeSoto 8,710 583,000 .552 1.35 2.20 3.05 5.91 17.6 42.8 164 593 36,100 34,000,000Indian Creek at State Line Road 8,315 2,850,000 11.5 47.4 79.5 108 180 441 1,420 14,600 77,100 1,360,000 92,800,000Kill Creek at 95th Street 8,483 256,000 .088 1.26 3.22 5.31 11.4 27.6 74.7 300 1,280 24,300 14,700,000Mill Creek at Johnson Drive 8,718 524,000 .199 3.99 6.71 9.50 17.5 38.3 145 821 4,000 136,000 33,700,000
66 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

In the category of dissolved solids and major ions, chloride was selected for additional evaluation and 

discussion in this report. Chloride, an ion of interest because 

of the aquatic-life criteria established by KDHE and USEPA, 

occurs naturally in various rock types. However, it generally 

occurs in low concentrations and is most likely to occur as an 

impurity (Hem, 1992). Potential sources include agricultural 

and industrial runoff, and WWTF discharges. In addition, 

chloride, in the form of sodium chloride (NaCl), calcium 

chloride (CaCl), and magnesium chloride (MgCl), is a major 

component of road de-icers (U.S. Environmental Protection 

Agency, 2002a). KDHE has established an acute aquatic-life 

criterion of 860 mg/L for chloride (Kansas Department of 

Health and Environment, 2005). The USEPA-recommended 

chronic freshwater quality criterion for chloride is 230 mg/L 

(U.S. Environmental Projection Agency, 2002b). In this report 

chloride concentrations are compared to the acute aquaticlife criterion of 860 mg/L and to the Secondary Drinking 

Water Regulation of 250 mg/L (U.S. Environmental Protection Agency, 2003a) which also corresponds to the Kansas 

chloride criterion for domestic water supply at the point of 

water supply diversion (Kansas Department of Health and 

Environment, 2005).

Like the other major ions, the regression models for 

chloride include specific conductance as the only explanatory variable (table 8). Uncertainty in the models is small for 

the most urban sites (Indian and Mill Creeks). Uncertainty 

associated with the chloride models for the Blue River and 

Kill Creek sites is larger in part because the range in chloride 

concentrations is smaller at these two nonurban sites (table 8). 

In addition, chloride generally makes up a smaller proportion 

of dissolved solids at nonurban sites where dissolved solids 

would be expected to originate from natural sources. Chloride concentrations in discrete samples ranged from 5.0 mg/L 

at the Kill Creek site to 1,678 mg/L at the Indian Creek site 

(table 8). Two discrete samples, collected in January 2004 and 

January 2007 at the Indian Creek site and affected by road-salt 

application, exceeded the KDHE criterion of 860 mg/L. Corresponding specific conductance in the discrete-sample dataset 

ranged from 160 μS/cm at the Kill Creek site to 5,710 μS/cm 

at the Indian Creek site.

The slopes of the chloride regression models are similar 

for the sites with comparable land use (fig. 14B). The slopes 

for the Blue River and Kill Creek regression models are similar, and the slopes for the Indian and Mill Creek models are 

similar, indicating similar chloride sources in the watersheds 

(predominantly agricultural sources in the first two watersheds 

and urban sources in the latter two watersheds). The steepest 

regression slope occurred in the Cedar Creek model, indicating larger chloride concentrations than at the other sites as 

specific conductance increased. The Cedar Creek watershed 

contains a larger percentage of industrial land use than the 

other four watersheds (table 1) which may result in varying 

principal sources of chloride possibly resulting in a different 

regression relation at this site.

Regression-estimated chloride concentrations were largest at the Indian and Mill Creek sites (fig. 21), the two most 

urban monitoring sites which also are affected by WWTFs. 

Figure 18. Cumulative estimated suspended-sediment loads and frequency of exceedance at five 

water-quality monitoring sites in Johnson County, Kansas, January 2005–December 2006.

0

10

20

30

40

50

60

70

80

90

100

Cumulative estimated suspended-sediment load, in percent

0 1 234567 8 9 10

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 67

Figure 19. Streamflow and cumulative suspended-sediment load at five water-quality monitoring sites in Johnson 

County, Kansas, 2005–06.

(A) Blue River at Kenneth Road (fig. 1)

0

0.10

1.0

10

100

1,000

10,000

100,000

Streamflow corresponding to cumulative suspended-sediment load, cubic feet per second (ft3/s)

25-year peak streamflow, 22,000 ft3/s

10-year peak streamflow, 15,800 ft3

/s

2-year peak streamflow, 6,570 ft3

/s

y = -67.8x + 6,780

R2

 = 0.81

(B) Cedar Creek near DeSoto (fig.1)

1

10

100

1,000

10,000

100,000

1

10

100

1,000

10,000

100,000

2-year peak streamflow, 6,240 ft3/s

10-year peak streamflow, 15,600 ft3

/s

25-year peak streamflow, 21,700 ft3

/s

 y = -45.1x + 4,520

 R2 = 0.82

(C) Indian Creek at State Line Road (fig. 1)

2-year peak streamflow, 6,680 ft3/s

10-year peak streamflow, 13,700 ft3

/s

25-year peak streamflow, 17,800 ft3

/s

y = -77.3x + 7,740

R2

 = 0.86

0 10 20 30 40 50 60 70 80 90 100

Percentage of total suspended-sediment load
68 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Lee and others (2005) reported that during base flow, chloride concentrations in samples at or immediately downstream 

from WWTFs generally were the largest in each watershed. 

Estimated chloride concentrations ranged from about 5 mg/L 

at the Cedar Creek site in 2006 to 1,500 mg/L at the Indian 

Creek site in 2006 (table 10). The median chloride concentration at each site in 2005 was similar to that in 2006, even 

though the maximum chloride concentration at the Indian 

and Mill Creek sites in 2006 was nearly double the respective 

maximums in 2005. Generally, the median chloride concentration from January 2005 through December 2006 at the Indian 

Creek site was about four times the median at the Kill Creek 

site (table 10). The steep upward slopes in the duration curves 

for the Indian and Mill Creek sites are a result of road-salt 

application during winter months (fig. 21). About 10 percent 

of the time, the Indian and Mill Creek sites were noticeably 

affected by increased chloride concentrations as a result of 

road-salt runoff, while there were no major effects from roadsalt application at the Blue River and Kill Creek monitoring 

sites (fig. 21). The effect of accumulated road salt on ground 

water and base flow throughout the remainder of the year is 

unknown. Studies have shown that road salt can accumulate in 

soil and groundwater resulting in elevated chloride even when 

no salt is being applied (Kaushal and others, 2005).

At the Indian Creek site during 2005–06, there was a 

50-percent probability of chloride concentration exceeding 

the 250-mg/L USEPA Secondary Drinking Water Regulation about 8 percent of the time, and exceeding the 860-mg/L 

KDHE acute aquatic-life criterion less than 1 percent of the 

time (fig. 22). Estimated annual chloride load at Indian Creek 

Figure 19. Streamflow and cumulative suspended-sediment load at five water-quality monitoring sites in Johnson 

County, Kansas, 2005–06.—Continued

1

10

100

1,000

10,000

100,000

2-year peak streamflow, 7,770 ft3/s

10-year peak streamflow, 18,400 ft3

/s

25-year peak streamflow, 25,000 ft3

/s

y = -46.4x + 4,640

R2

 = 0.85

2-year peak streamflow, 6,470 ft3/s

10-year peak streamflow, 15,900 ft3

/s

25-year peak streamflow, 22,000 ft3

/s

0

1

10

100

1,000

10,000

100,000

y = -46.5x + 4,650

R2

 = 0.85

(E) Mill Creek at Johnson Drive (fig.1)

(D) Kill Creek at 95th Street (fig.1)

Streamflow corresponding to cumulative suspended-sediment load, cubic feet per second (ft3/s)

0 10 20 30 40 50 60 70 80 90 100

Percentage of total suspended-sediment load
Regression-Estimated Constituent Concentrations, Densities, Loads, and Yields 69

in 2006 was more than twice that of Mill Creek and more than 

25 times the estimated annual load at Kill Creek (table 11). 

About 50 percent of the total chloride load during 2005–06 

occurred in less than 10 percent of the time at all five monitoring sites (fig. 23). Estimated yield characteristics were similar 

to load in that the Indian Creek chloride yield in 2006 was 

more than double that of Mill Creek, and more than 20 times 

that of Kill Creek (table 11).

Seasonal differences in chloride concentration and 

loads occur because of differences in streamflow sources and 

effects of road-salt application. Winter chloride concentrations 

(November 1–February 28) generally were larger than other 

seasons at all monitoring sites in part because ground water is 

a natural source of chloride and during the winter streamflow 

originates primarily from ground water with minimal dilution effects from rainfall. At urban sites, very high chloride 

concentrations during the winter (fig. 24) were caused by 

application of deicing chemicals to keep roadways clear of 

snow and ice. Nationwide, the most commonly used and 

economical deicer is sodium chloride (salt), which is effective because it lowers the freezing point of water, preventing 

ice and snow from bonding to the pavement and allowing 

easy removal by snow plows (U.S. Environmental Protection 

Agency, 2002a). During two winter storms in December 2005, 

an estimated 2,550 tons of salt, 917 tons of salt/sand mix, and 

8,000 gal of calcium chloride were applied to roadways in 

Overland Park, Kansas, (City of Overland Park, written commun., April 2005) which includes a large part of the Indian 

Creek watershed. Deicing chemicals concentrate in runoff and 

enter surface and ground water, potentially causing problems 

for aquatic environments. The Indian and Mill Creek sites 

were most affected by road-salt application, and the maximum 

concentrations were larger during 2006 (table 11) when annual 

precipitation and streamflow were less than normal compared 

to 2005. In 2005, 39 percent (Kill Creek) to 57 percent (Indian 

Creek) of the total annual chloride load occurred during the 

winter (November 1 through February 28); in 2006, 23 percent 

(Kill Creek) to 46 percent (Indian Creek) of the total annual 

load occurred during the winter (table 11).

Two apparently similar chloride runoff occurrences 

resulting from road-salt application can nevertheless have 

different effects on stream chemistry, depending on rainfall, 

snowmelt, and runoff. Cedar, Indian, and Mill Creeks were 

affected by road-salt runoff in January and February 2005 

(fig. 25). During that time at Indian Creek, for example, the 

first chloride increase, caused primarily by warming temperatures and gradual runoff from snowmelt, resulted in a 

10-day period when chloride concentrations were larger 

than 250 mg/L, and total chloride load during that period 

was 725 tons. The second chloride increase resulted in about 

6 days when chloride concentration was larger than 250 mg/L, 

but the chloride load was nearly double the load during the 

first chloride increase at 1,330 tons because of the larger 

associated streamflow. These two periods of runoff contributed 

19 percent of the total chloride load in Indian Creek in 2005.

Figure 20. Estimated suspended-sediment load during June 2005 at the Blue River monitoring site, Johnson 

County, Kansas.

0.01

0.1

1.0

10

100

1,000

10,000

100,000

Estimated suspended-sediment load, in tons per day

1

10

100

1,000

10,000

Streamflow, in cubic feet per second

1 5 10 15 20 25 30

June 2005

90-percent 

prediction interval

Estimated hourly 

sediment load

Storm runoff June 3–5

(about 50 percent of total

sediment load in 2005)

Streamflow
70 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Fecal-Indicator Bacteria

Fecal coliform, E. coli, and enterococci are the three most 

common types of bacteria used as indicators of pathogens in 

surface water. Indicator bacteria are used to evaluate the sanitary quality of water and its use as a public water supply and 

for recreational activities such as swimming, wading, boating, 

and fishing (American Public Health Association and others, 

1995). The presence of E. coli indicates the possible presence 

of pathogens found in feces of warmblooded animals (Dufour, 

1977). These indicator bacteria and pathogens may cause 

human diseases ranging from mild diarrhea to respiratory disease, septicemia, meningitis, and polio (Dufour, 1977).

Kansas water-quality criteria for E. coli bacteria require 

stream sites to be classified and regulated according to designated use and accessibility. Most segments of the Blue River 

and Cedar and Mill Creeks have been designated as Class C, 

indicating primary contact recreation not open to and accessible by the public. Most segments of Kill Creek are Class B, 

indicating primary contact recreation accessible by the public 

with landowner permission. Designated uses for Indian Creek 

have not been determined by the State (Kansas Department of 

Health and Environment, 2005). Primary contact recreational 

use criteria for E. coli state that for the three use classifications of water (Appendix 1), a geometric mean of five samples 

collected during separate 24-hour periods within a 30-day 

period cannot exceed 160, 262, and 427 colony-forming units 

per 100 mL of water from April through October each year. 

From November through March primary contact criteria for 

E. coli are 2,358 or 3,843 col/100 mL for the three use classes 

(Kansas Department of Health and Environment, 2005). 

Geometric means were not applied in this report because 

the data used are continuous rather than five discrete samples 

collected during separate 24-hour periods within 30-day periods, as described by the criteria. A direct comparison to the 

actual criteria values, however, is considered meaningful when 

evaluating continuous data.

All regression models for indicator bacteria included 

turbidity as the only explanatory variable (table 8). Indicator 

bacteria have been shown to be closely related to sediment 

because bacteria attach to sediment particles and because sediment concentration is closely related to turbidity (Rasmussen 

and Ziegler, 2003; Rasmussen and others, 2005). R2 values 

ranged from 0.67 for fecal coliform at the Indian Creek site 

to 0.90 at the Cedar Creek site for enterococci, and RMSE 

values ranged from 0.445 for E. coli at the Cedar Creek site 

to 0.668 for enterococci at the Mill Creek site (table 8). Some 

regression models for indicator bacteria are characterized by 

somewhat high variability in data (table 8) and in the relation 

between bacteria and sediment (table 9).

E. coli bacteria models for each site are shown in figure 14C. The models were developed using discrete samples 

ranging from less than 10 to greater than 20,000 col/100 

mL at each site and turbidity values ranging from less than 

10 to greater than 900 FNUs (table 8). The relation between 

turbidity and E. coli bacteria at the Indian Creek site is different from the other sites (fig. 14C). The slope is less and the 

y-intercept is larger, indicating that at small turbidity values, 

E. coli densities at the Indian Creek site are larger relative to 

the other sites. The Indian Creek site is located in the most 

urban watershed. Lee and others (2005) found larger indicator bacteria densities at stream sites in urban areas (upstream 

from WWTFs) than in nonurban areas. Urban sources, such 

as leaking sewage lines, pet waste, or regrowth in sediment, 

also may cause larger bacteria densities. In addition, the Indian 

Creek site is immediately downstream from a WWTF, which 

likely is affecting indicator bacteria densities. The small 

indicator bacteria densities found in the WWTF discharge may 

be enough to affect indicator bacteria densities at the Indian 

Creek monitoring site during low streamflow conditions. Lee 

and others (2005) found that resuspension of streambed sediment accounted for less than 1 percent of the bacteria density 

in stormflow samples.

E. coli density at the Indian Creek site was usually the 

largest of the five monitoring sites (fig. 26) with a median 

density more than double that of any other site, and at least 

15 times the density at the Blue River site (table 10). At the 

Indian Creek site, the primary criterion (262 col/100 mL) was 

exceeded about 65 percent of the time, and the secondary 

criterion (2,358 col/100 mL) was exceeded about 10 percent of 

the time (fig. 26). The primary contact criterion was exceeded 

between about 8 and 25 percent of the time at the other monitoring sites. The secondary contact criterion was exceeded less 

than 5 percent of the time at the other sites. The Blue River 

and Cedar Creek sites had the smallest bacteria densities most 

of the time (fig. 26). In 2005–06, estimated densities at Indian 

Creek generally were largest during the winter, except during 

the 0–20 percent exceedance period (fig. 27A) compared to the 

other sites, which experienced the smallest concentrations 

Table 13. Percentage of annual suspended-sediment load that occurred during the single largest storm runoff for 2005 at five waterquality monitoring sites in Johnson County, northeast Kansas.

Continuous 

in-stream 

monitoring site 

(fig. 1)

Dates of 

largest storm 

runoff in 2005

Peak streamflow, in 

cubic feet per 

second

Percentage 

of annual 

suspendedsediment load

Blue River at 

Kenneth 

Road

June 3–5 9,840 52

Cedar Creek 

near DeSoto

June 3–6 4,390 41

Indian Creek 

at State Line 

Road

June 3–5 10,500 31

Kill Creek at 

95th Street

June 3–6 5,820 42

Mill Creek 

at Johnson 

Drive

August 19–22 8,280 20

 
Results of Selected Discrete-Sample Analysis 71

Figure 21. Duration curves for estimated chloride concentration at five water-quality monitoring sites in 

Johnson County, Kansas, March 2004–December 2006.

Figure 22. Frequency and probability of exceeding chloride criteria at the Indian Creek monitoring 

site, Johnson County, Kansas, January 2005–December 2006.

0

200

400

600

800

1,000

1,200

1,400

1,600

Kansas Department of Health 

and Environment (2005) acute 

aquatic-life criterion (860 mg/L)

U.S. Environmental Protection 

Agency (2003a) Secondary DrinkingWater Regulation (250 mg/L)

Estimated chloride concentration, in milligrams per liter (mg/L)

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

0

10

20

30

40

50

60

70

80

90

100

Probability of exceeding criterion

250-mg/L criterion (U.S. Environmental 

 Protection Agency, 2003a)

860-mg/L criterion (Kansas Department

 of Health and Environment, 2005)

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent
72 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 23. Cumulative estimated chloride loads and frequency of exceedance at five water-quality 

monitoring sites in Johnson County, Kansas, 2005–06.

Figure 24. Seasonal chloride concentration duration curves at the Indian Creek monitoring site, 

Johnson County, Kansas, January 2005–December 2006.

0

10

20

30

40

50

60

70

80

90

100

Cummulative estimated chloride load, in percent

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

0

200

400

600

800

1,000

1,200

1,400

1,600

Estimated chloride concentration, in milligrams per liter (mg/L)

November−February

March–July

August–October

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Kansas Department of Health 

and Environment (2005) acute 

aquatic-life criterion (860 mg/L)

U.S. Environmental Protection 

Agency (2003a) Secondary DrinkingWater Regulation (250 mg/L)
Results of Selected Discrete-Sample Analysis 73

during the winter (Cedar, for example, in figure 27B). In 

2005–06 at the Blue River site during April through October 

when water-quality criteria apply, there was a 50-percent 

probability of exceeding the primary criterion about 8 percent 

of the time and exceeding the secondary criterion 1 percent 

of the time (fig. 28A). At the Indian Creek site, there was a 

50-percent probability of exceeding the primary criterion 

about 30 percent of the time and exceeding the secondary 

criterion 10 percent of the time (fig. 29B).

During 2005–06, the largest annual E. coli bacteria 

loads occurred at the Indian Creek site where the loads were 

at least double that of any other site (table 11). Also during 

2005–06, more than 90 percent of the total E. coli bacteria 

load at the Cedar Creek site occurred in less than 1 percent 

of the time, generally during storm runoff, compared to the 

Indian Creek site where about 80 percent of the total E. coli 

load occurred less than 1 percent of the time (fig. 29). The 

largest annual bacteria yields occurred at the Indian Creek 

site as well (table 11). Potential urban sources of bacteria in 

Indian Creek include leaking sewer lines, pet waste, wildlife, 

WWTF discharges and bypasses, and unauthorized dumping. 

Total annual E. coli loads at the Cedar monitoring site, which 

is located in the downstream part of the watershed, in 2005 

(4,690,000 billion colonies) and 2006 (820,000 billion colonies) bracketed the total annual E. coli loads in the upstream 

parts of the watershed reported by Mau and others (2004), in 

2001 (3,900,000 billion colonies) and 2002 (1,400,000 billion 

colonies). Potential nonurban sources of bacteria in less urban 

watersheds include livestock, leaking septic systems, and wildlife waste. Permitted confined animal facilities located in the 

upstream part of the Blue River watershed have a combined 

animal count of about 1,500 animals, in the upstream part of 

Cedar and Kill Creeks, 250 and 950 animals, respectively, 

and in the downstream part of Mill Creek about 100 animals 

(Eileen Hack, Johnson County Stormwater Management Program, written commun., 2004).

E. coli bacteria densities at all sites increased by several orders of magnitude during storm runoff, indicating that 

bacteria in Johnson County streams originates primarily from 

nonpoint sources. This finding is consistent with results of previous studies. Lee and others (2005) reported that E. coli densities and loads were significantly larger (two to four orders 

of magnitude) in stormflow samples than base-flow samples. 

Wilkison and others (2006) found that bacteria densities in the 

Blue River Basin increased by several orders of magnitude 

during storms because most of the bacteria originated from 

nonpoint sources.

In addition, when fecal coliform bacteria load from 

the Blue River WWTF (calculated from data provided by 

D. Nolkemper, Johnson County Wastewater, written commun., 

September 2007), which discharges just downstream from the 

Blue River monitoring site, was added to the total load at the 

Blue River monitoring site (table 11), less than 1 percent of 

the total downstream Blue River fecal coliform bacteria load 

Figure 25. Elevated chloride concentrations during snowmelt as a result of road-salt application at 

five water-quality monitoring sites in Johnson County, Kansas, January–February 2005.

0

100

200

300

400

500

600

700

800

900

21 26 31 5 10

January February

2005

15 20

Estimated dissolved chloride concentration, in milligrams per liter (mg/L)

Monitoring sites

(fig. 1)

Blue River at

 Kenneth Road

Cedar Creek 

 near DeSoto

Indian Creek at

 State Line Road

Kill Creek at 

 95th Street

Mill Creek at

 Johnson Drive

U.S. Environmental 

Protection Agency 

(2003a) Secondary 

Drinking-Water 

Regulation (250 mg/L)
74 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

originated from the WWTF (fig. 30). The 2005 and 2006 load 

calculations for fecal coliform bacteria from the two WWTFs 

on Indian Creek indicated that less than 3 percent of the total 

fecal coliform bacteria load at the Indian Creek monitoring 

site originated from WWTFs and more than 97 percent of the 

load originated from nonpoint sources (fig. 30).

Results of Selected Discrete-Sample 

Analysis

All samples collected during this study were analyzed for 

nutrients and pesticides, and an attempt was made to develop 

regression models for them. However, because significant 

explanatory variables were not found for nutrients at all sites 

and because of large variability in some of the existing models, discrete data, rather than continuous data, are used in this 

report for making comparisons between the five watersheds.

Nutrients

Nutrients, including various forms of nitrogen and 

phosphorus, are essential for proper plant and animal growth 

but in excess can lead to eutrophication, algal blooms, fish 

kills, low dissolved oxygen, taste and odor problems, and 

other disruptions in aquatic ecosystems. Runoff from both 

urban and nonurban sources contributes to nutrient concentrations in streams. Typical nutrient sources include municipal 

wastewater discharge, fertilizers, and runoff from livestock 

operations (Masters, 1991). In addition, natural background 

concentrations of total nitrogen and total phosphorus in 

headwater streams within the study area have been estimated 

to be 0.15 to 0.30 mg/L and 0.06 mg/L or greater, respectively 

(Smith and others, 2003). Kansas has no numerical waterquality criteria for total nitrogen or total phosphorus but has 

set a goal of reducing export of these nutrients from the State 

by 30 percent (Kansas Department of Health and Environment, 2004b). USEPA Ecoregion IX, Level III subecoregion 

40 (Central Irregular Plains which includes Johnson County) 

recommended criteria are 0.855 mg/L total nitrogen and 

0.0925 mg/L for total phosphorus (U.S. Environmental Protection Agency, 2003b).

Regression models for nutrient species were developed 

when significant continuous explanatory variables were found 

(table 8). Generally, variability in total nutrient models was 

minimal at the two nonurban sites (Blue River and Kill Creek) 

compared to the sites where nutrient sources were more 

diverse (Mill and Indian Creeks). No significant explanatory 

variables were found for total nitrogen or total phosphorus 

at the Cedar Creek site. Because watershed comparisons are 

incomplete without including all sites, discussion of estimated 

nutrient values in this report is limited. However, duration 

estimates for estimated concentrations and loads are provided 

in tables 10 and 12 and continuous estimated data are available 

on the World Wide Web at http://ks.water.usgs.gov.

Figure 26. Duration curves for estimated Escherichia coli (E. coli) bacteria density at five water-quality 

monitoring sites in Johnson County, Kansas, March 2004–December 2006.

0

1

10

100

1,000

100,000

10,000

1,000,000

10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Estimated Escherichia coli bacteria density,

in colonies per 100 milliliters of water (col/100mL)

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Secondary contact recreation criterion

(Kansas Department of Health and

Environment, 2005) at any time during

the year for a geometric mean of five

samples within a 30-day period

(2,358 col/100 mL)

Primary contact recreation criterion

(Kansas Department of Health and

Environment, 2005) from April through

October, geometric mean of five samples

within a 30-day period (262 col/100 mL)
Results of Selected Discrete-Sample Analysis 75

Figure 27. Seasonal duration curves for estimated Escherichia coli (E. coli) bacteria density at the 

(A) Indian Creek and (B) Cedar Creek water-quality monitoring sites, January 2005–December 2006.

1

10

100

1,000

10,000

100,000

November–February

March–July

August–October

November–February

March–July

August–October

Estimated Escherichia coli bacteria density, in colonies per 100 milliliters (col/1oomL)

1

10

100

1,000

10,000

100,000

1,000,000

(A) Indian Creek monitoring site (06893390, fig. 1)

(B) Cedar Creek monitoring site (06892495, fig. 1)

Secondary contact recreation criterion 

(Kansas Department of Health and 

Environment, 2005) at any time during 

the year for a geometric mean of five

samples within a 30-day period 

(2,358 col/100 mL)

Primary contact recreation criterion

(Kansas Department of Health and 

Environment, 2005) from April through 

October, geometric mean of five samples 

within a 30-day period (262 col/100 mL)

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

Secondary contact recreation criterion 

(Kansas Department of Health and 

Environment, 2005) at any time during 

the year for a geometric mean of five

samples within a 30-day period 

(2,358 col/100 mL)

Primary contact recreation criterion

(Kansas Department of Health and 

Environment, 2005) from April through 

October, geometric mean of five samples 

within a 30-day period (262 col/100 mL)
76 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 28. Probability of exceeding Escherichia coli bacteria criteria at the (A) Blue River and

(B) Indian Creek water-quality monitoring sites, in Johnson County, Kansas, January 2005–

December 2006. Recreation criteria from Kansas Department of Health and Environment (2005).

0

10

20

30

40

50

60

70

80

90

100

Primary criterion (262 col/100 mL, April 1–October 31)

Secondary criterion (2,358 col/100 mL)

Primary criterion (262 col/100 mL, April 1–October 31)

Secondary criterion (2,358 col/100 mL)

0

10

20

30

40

50

60

70

80

90

100

Probability of exceeding criterion, in percent

(B) Indian Creek monitoring site (06892290, fig. 1)

0 10 20 30 40 50 60 70 80 90 100

Frequency of exceedance, in percent

(A) Blue River monitoring site (06893100, fig.1)
Results of Selected Discrete-Sample Analysis 77

Figure 29. Cumulative estimated Escherichia coli (E. coli) bacteria loads and frequency of exceedance at five water-quality monitoring sites in Johnson County, Kansas, January 2005–

December 2006.

Figure 30. Total annual estimated fecal coliform bacteria loads and loads originating from wastewatertreatment-facility (WWTF) discharges to the Blue River and Indian Creek, Johnson County, Kansas, January 

2005–06 (fecal coliform bacteria loads from WWTF discharges calculated from density and discharge data 

provided by D. Nolkemper, Johnson County Wastewater, written commun., September 2007).

0

10

20

30

40

50

60

70

80

90

100

Cummulative estimated Escherichia coli bacteria load, in percent

012345 6 7 8 9 10

Frequency of exceedance, in percent

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

2005 2006 2005 2006

Blue River Indian Creek

Fecal coliform bacteria load, in billions of colonies

WWTF discharge load

Total downstream load 6,500,000

12,000

3,410,000

2,780

15,100,000

478,000

20,300,000

130,000
78 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Turbidity was found to be a significant explanatory variable for total nitrogen and total phosphorus at all monitoring 

sites except the Cedar Creek site. The best models, as indicated by large R2

 values and small RMSEs, were for the Blue 

River and Kill Creek sites, the two least urban watersheds and 

the two sites with the strongest correlations between suspended-sediment concentration and total nitrogen and phosphorus (table 9). The Cedar Creek watershed contains more 

impoundments than the other watersheds (indicated by the 

larger percentage of surface water compared to the other sites, 

table 1), which may interfere with relations between sediment 

and nutrients. By trapping sediment, impoundments also can 

trap nutrients that attach to sediment. Variability in the Indian 

Creek regression models for total nitrogen and total phosphorus likely is a result of the effects of WWTFs and changing 

predominant sources at that site during various streamflow 

conditions. Discrete-sample data indicated that the median 

total phosphorus concentrations at the Indian Creek site during 

the sample-collection period (1.0 mg/L, table 14) was about 

60 percent larger than median concentrations at the Cedar and 

Mill Creek sites (each about 0.6 mg/L) and more than double 

those at the Kill Creek and the Blue River sites (each about 

0.4 mg/L) (table 14).

Concentrations of different nutrient species varied 

according to primary sources and streamflow conditions. 

Discrete samples collected during various streamflow conditions from October 2002 through January 2006 indicated that 

the largest total nitrogen concentrations occurred at the Indian 

Creek monitoring site during streamflows less than 200 ft3/s, 

with the exception of one sample from the Cedar Creek site 

and one sample from the Mill Creek site (fig. 31A). The largest 

proportion of nitrogen in those samples was nitrate (fig. 31B) 

indicating that WWTFs were likely a primary source of nitrogen during lower streamflow conditions. Ammonia, which 

can be toxic to aquatic life, occurred in the largest concentrations at the Indian Creek site during low flow. The largest total 

phosphorus concentrations at the Blue, Kill, and Mill Creek 

monitoring sites occurred during larger streamflows, whereas 

the largest total phosphorus concentrations at the Cedar and 

Indian Creek sites occurred during flow less than 200 ft3/s 

(fig. 32). Larger total phosphorus concentrations during lower 

flows indicate WWTFs were a primary source, which is 

consistent with findings reported by Lee and others (2005). 

Larger concentrations of total nutrients during storm runoff 

at the Blue River and Kill Creek sites indicate that nonpoint 

sources are predominant in those primarily agricultural watersheds. Large concentrations of total nutrients during both base 

flow and storm runoff at the more urban sites indicate that 

the streams are affected by both point and nonpoint sources of 

nutrients.

Estimates indicate that about 40 percent of the total nitrogen load in 2005 and 70 percent of the total nitrogen load in 

2006 originated from the WWTF discharges to the Blue River 

just downstream from the monitoring site. Nutrient loads from 

WWTFs were calculated using concentration and discharge 

data provided by D. Nolkemper, Johnson County Wastewater, 

written commun., September 2007. One-fourth (in 2005) to 

one-half (in 2006) of the downstream total phosphorus load in 

the Blue River originated from WWTF discharges. Total nitrogen load discharged from the two Indian Creek WWTFs was 

about 65 percent of estimated total nitrogen load at the downstream Indian Creek monitoring site in 2005 and 90 percent of 

the estimated downstream total nitrogen load in 2006 (fig. 33). 

Total phosphorus load from the Indian Creek WWTFs was 

90 percent of the total phosphorus load at the downstream 

monitoring site in 2005 and 120 percent of the downstream 

total phosphorus load in 2006 (fig. 33).

Nutrient loads from the WWTFs were nearly the same in 

2005 and 2006. However, because less precipitation occurred 

in 2006, nutrient loads originating from runoff were smaller 

compared to 2005. At Indian Creek, the total phosphorus load 

from the WWTFs exceeded the downstream total phosphorus load in 2006 primarily because of additional settling of 

nutrients along with sediment that occurred within the distance 

between the WWTF discharges and the monitoring sites, 

with less flushing from stormwater runoff. The largest of the 

two WWTFs on Indian Creek will be undergoing upgrades 

and is scheduled to begin biological nutrient removal in 2010 

(D. Nolkemper, Johnson County Wastewater, written commun., September 2007).

Pesticides

In 2001, an estimated 1,203 million lbs of conventional 

pesticides were sold in the United States, the majority of 

which were herbicides (58 percent) and insecticides (28 percent) (Kiely and others, 2004). An estimated 76 percent of the 

total was used for agricultural purposes, 13 percent for commercial/industrial/government purposes, and 11 percent for 

home and garden purposes (Kiely and others, 2004). Nationwide studies indicate that pesticides and their degradates typically (at least 94 percent of the time) are present in water from 

streams throughout most of the year in both agricultural and 

urban watersheds (Gilliom and others, 2006). The agricultural 

pesticides detected most frequently and in largest concentrations were the herbicides acetochlor, alachlor, atrazine, 

cyanazine, and metolachlor. The most common urban pesticides were the herbicides 2,4-D, diurlon, prometon, simazine, 

and tebuthiuron, and the insecticides carbaryl, chlorpyrifos, 

and diazinon. Nationwide, pesticides seldom were found in 

concentrations large enough to affect humans, but often in 

concentrations that may have effects on aquatic life and fisheating wildlife (Gilliom and others, 2006).

Regression models for providing continuous estimates 

of pesticides in Johnson County streams were not developed 

because no continuously measured explanatory variables 

were found to be significant. Regression models for pesticides 

have been developed for other predominantly agricultural 

stream sites (Christensen and others, 2000; Rasmussen and 

others, 2005), but more mixed land uses in Johnson County 

watersheds likely contributed to large statistical variability in 

the relations between variables.
Results of Selected Discrete-Sample Analysis 79

Table 14. Results of analysis of nutrients in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.

[All concentrations are given in milligrams per liter; N, nitrogen; P, phosphorus; <, less than]

Concentrations

Nitrogen, 

ammonia, as N 

Nitrogen, 

nitrite, 

as N

Nitrogen, 

nitrate, 

as N

Nitrogen, 

ammonia plus 

dissolved 

organic 

nitrogen, 

as N

Nitrogen, 

ammonia 

plus total 

organic 

nitrogen, 

as N

Nitrogen, 

nitrite 

plus 

nitrate, 

as N

Total 

nitrogen

Phosphorus, 

total

Phosphorus, 

dissolved

Phosphorus, orthophosphate, 

as P

Blue River at Kenneth Road (fig. 1)

Number of samples 17 20 20 20 20 20 20 20 20 20

Maximum value .26 .04 1.13 2.40 7.60 1.15 8.75 2.45 .16 .12

Minimum value <.04 <.02 .06 .07 .30 .08 .59 .06 <.01 <.01

Mean .07 .02 .61 .64 1.84 .63 2.47 .51 .08 .06

Median .04 .02 .62 .54 1.52 .64 2.19 .38 .08 .06

Cedar Creek near DeSoto (fig. 1)

Number of samples 22 22 22 22 22 22 22 22 22 22

Maximum value .12 .08 7.83 1.00 3.10 7.90 9.20 2.43 2.27 2.22

Minimum value <.04 <.02 .24 .30 .40 .26 1.37 .20 .05 .04

Mean .06 .03 1.65 .58 1.30 1.67 2.97 .69 .41 .38

Median .04 .02 1.10 .60 1.10 1.12 2.54 .59 .20 .19

Indian Creek at State Line Road (fig. 1)

Number of samples 25 25 25 25 25 25 25 25 25 25

Maximum value 1.27 .31 1.40 2.60 8.04 1.70 12.50 2.96 2.91 2.76

Minimum value <.04 <.02 .41 .50 .89 .43 2.30 .54 .07 .06

Mean .34 .10 3.11 1.14 2.36 3.21 5.57 1.22 .71 .67

Median .19 .08 1.93 1.10 1.80 2.12 4.79 1.01 .41 .38

Kill Creek at 95th Street (fig. 1)

Number of samples 22 25 25 25 25 25 25 25 25 25

Maximum value .17 .05 1.97 1.30 6.20 2.02 7.31 2.14 .76 .73

Minimum value <.04 <.02 .03 .20 .30 <.05 .35 .09 .03 .02

Mean .06 .02 .63 .61 1.74 .65 2.40 .58 .15 .13

Median .04 .02 .55 .57 1.20 .55 1.98 .39 .12 .10

Mill Creek at Johnson Drive (fig. 1)

Number of samples 22 23 23 23 23 23 23 23 23 23

Maximum value .34 .11 9.29 1.00 5.80 9.40 1.90 2.38 1.54 1.50

Minimum value <.04 <.02 .26 .20 .40 .28 .68 .22 .09 .02

Mean .07 .03 1.91 .54 1.73 1.94 3.67 .85 .32 .29

Median .05 .02 1.35 .50 1.10 1.37 2.74 .62 .19 .18
80 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 31. Concentrations of (A) total nitrogen and (B) nitrate in relation to streamflow at five waterquality monitoring sites in Johnson County, Kansas, October 2002–January 2006.

0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Total nitrogen, in milligrams per liter

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

Low flow

Low flow

0

2.0

4.0

6.0

8.0

10.0

12.0

0 1.0 10 100 1,000 10,000 100,000

Streamflow, in cubic feet per second

Nitrate as nitrogen, in milligrams per liter

(A) Total nitrogen

(B) Nitrate as nitrogen
Watershed Characteristics Affecting Water Quality in Johnson County Streams 81

Discrete samples collected for the study described in this 

report indicated that many of the same pesticides frequently 

found nationwide also were most common in Johnson County 

streams (table 15). Atrazine (an herbicide often used in crop 

production) was common at all monitoring sites. Prometon 

(an extensively used urban herbicide) also was detected in 

more than 90 percent of samples at each site. Metolachlor (a 

common agricultural herbicide) was found in the majority of 

samples at all sites except Kill Creek, where it was detected 

in about two-thirds of the samples. Simazine (another extensively used herbicide usually associated with urban uses) was 

found in all samples from all five sites but was detected most 

frequently in samples from the Cedar Creek site. The largest 

concentrations of all pesticides occurred in samples collected 

during storm runoff, usually in the spring.

Atrazine was the most commonly detected pesticide 

at all five monitoring sites. However, concentrations in the 

more agricultural watersheds (Blue River, Cedar Creek, and 

Kill Creek) were largest, exceeding the KDHE aquatic-life 

criterion of 3.0 μg/L in one sample from the Blue River, 

two samples from Cedar Creek, and three samples from 

Kill Creek. Each exceedance occurred during storm runoff 

in April, May, or June. Larger concentrations of atrazine in 

Indian Creek samples collected during base flow compared 

to stormflow indicated that a major source of atrazine in that 

watershed is wastewater discharge, likely originating from 

municipal water supply, as first proposed by Lee and others 

(2005). The primary sources of drinking water in Johnson 

County are the Kansas and Missouri Rivers, both of which 

drain large agricultural watersheds and are known to contain 

atrazine most of the year (Goolsby and Battaglin, 1993; Rasmussen and others, 2005). Treated water contained atrazine 

concentrations ranging from 0.2 to 0.6 μg/L (Water-One, 

2004). In addition, studies have found atmospheric transport 

from agricultural areas can be a notable source of atrazine in 

streams (Cromwell and Thurman, 2000; Hampson and others, 

2000).

Watershed Characteristics Affecting 

Water Quality in Johnson County 

Streams

Hydrologic conditions, land use, contaminant sources, 

and human activity are the most important factors affecting water quality in Johnson County streams. Watershed 

characteristics, including geology, soils, and topography 

also affect water quality. Hydrologic conditions determine 

streamflow during storm runoff and affect both point and 

nonpoint contaminants in streams. Streamflow is the transport 

mechanism for delivering and moving water-quality constituents in streams. Streamflow characteristics affect constituent 

concentrations, rate of delivery and transport (volume and 

velocity), and constituent loads (volume). Precipitation, primarily the amount, frequency, and intensity of rainfall, is the 

fundamental factor contributing to streamflow and affecting 

Figure 32. Concentrations of total phosphorus in relation to streamflow at five water-quality 

monitoring sites in Johnson County, Kansas, October 2002–January 2006.

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Total phosphorus, in milligrams per liter

Monitoring sites (fig. 1)

Blue River at Kenneth Road

Cedar Creek near DeSoto

Indian Creek at State Line Road

Kill Creek at 95th Street

Mill Creek at Johnson Drive

0 1.0 10 100 1,000 10,000 100,000

Streamflow, in cubic feet per second

Low flow
82 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

transport of nonpoint contaminant sources. Because just two 

complete calendar years (2005 and 2006) of continuous data 

have been collected at all five Johnson County monitoring 

sites to date, and four complete calendar years (2003, 2004, 

2005, 2006) of continuous data have been collected at two 

sites (Cedar and Mill Creeks), thorough analysis of the effects 

of hydrologic variability on stream-water quality depends on 

additional data collection and interpretation. However, data 

collected in 2004 and 2005 indicate that just a few large storm 

runoffs lasting a few days can account for more than 50 percent of constituent loads in streams, particularly for sediment, 

chloride from road-salt runoff, and bacteria.

Besides precipitation, the other major source of streamflow in Johnson County is wastewater effluent. WWTFs play 

an important role in streamflow by sustaining base flow. The 

Indian Creek monitoring site is less than 1.4 mi downstream 

from the largest quantity of WWTF discharge of the five sites 

monitored. Lee and others (2005) found that during base flow, 

the majority of streamflow at three of the continuously monitored sites (Cedar, Indian, and Kill Creeks) originated from 

WWTF discharges as far as 13 mi upstream, and streamflow at 

the Mill Creek monitoring site also may often consist primarily of WWTF discharge, but rainfall during data collection 

may have affected estimates. At the Cedar, Indian, Kill, and 

Mill Creek sites, it is likely that streamflow was affected by 

WWTF discharge during normal flow as well. Normal flow 

could be considered that flow within the 25th and 75th percentile (fig. 4; http://water.usgs.gov/waterwatch). In this study, 

only the Blue River site was unaffected by WWTF discharge 

at the monitoring site. However, wastewater does discharge 

into the Blue River just downstream from the monitoring site, 

and therefore, water quality is expected to be different downstream from the monitoring site.

A number of factors associated with urbanization can 

affect water quality. Urban runoff and treated wastewater 

may have increased concentrations of nutrients, pesticides, 

metals, organic compounds, and dissolved ions (Heany and 

Huber, 1984; Zampella, 1994; Paul and Meyer, 2001). Lower 

infiltration capacity of watersheds in urban environments 

with greater amounts of impervious surfaces may inhibit the 

ability of streams to sustain base flow (Finkenbine and others, 

2000; Dodds, 2002). Urbanization affects sediment supply and 

transport differently during the construction phase and postconstruction phase, as summarized by Paul and Meyer (2001). 

During the construction phase, erosion of exposed soils 

leads to larger sediment loads (Leopold, 1968). This effect 

intensifies in more sloped watersheds and generally occurs 

during a few large floods (Wolman, 1967). The increase in 

sediment supply leads to bed aggradation, and stream depths 

may decrease resulting in decreased channel capacity, larger 

floods, and overbank sediment deposition (Wolman, 1967). 

The aggradation phase is followed by an erosional phase, during which channel erosion is the largest source of sediment. 

Increases in impervious surface area substantially increase the 

frequency or volume of bankfull floods leading to a general 

deepening (incision) and widening of the channel (Booth, 

1990). After incision, channels migrate laterally and bank erosion begins (Trimble, 1997). In developed urban streams, the 

majority of sediment being transported originates from channel erosion rather than hillside erosion (Trimble, 1997).

Impervious surfaces produce overland flow and large 

quantities of runoff even at moderate rainfall intensities 

(Arnold and Gibbons, 1996). Impervious surface area also 

has been found to be highly correlated with urban intensity and a good integrator of urban land-use conditions 

(McMahon and Cuffney, 2000), making it a useful surrogate 

for urban intensity.

In Johnson County, as impervious surface area increased, 

so did total annual yield for most water-quality constituents in 

2005 and 2006. Examining suspended-sediment, chloride, and 

E. coli bacteria yields (fig. 34), the three monitoring sites with 

less than 4 percent impervious surface area (table 1) clustered 

together with smaller yields, and Indian Creek with 24 percent 

impervious surface area, had considerably larger yields. 

Suspended sediment may increase in urban areas because of 

more exposed soils at construction sites, increased streamflow 

velocities contributing to more streambed and bank erosion, 

lack of riparian habitats for protecting soils from erosion, 

and settling sediment from water. Urban sources of chloride 

(road-salt runoff, WWTF discharge, industrial runoff) contributed more than nonurban sources (geology). Urban sources of 

E. coli bacteria (leaky sewer lines, pet waste, wildlife, WWTF 

discharges and bypasses, and unauthorized dumping) also 

generally contributed more than nonurban sources (livestock, 

leaky septic systems, and wildlife).

Figure 33. Annual estimated total nitrogen and total phosphorus loads 

and loads originating from wastewater-treatment facility (WWTF) 

discharges to the Blue River and Indian Creek, Johnson County, Kansas, 

2005–06 (nutrient loads from wastewater-treatment facility discharges 

calculated from concentration and discharge data provided by D. Nolkemper, Johnson County Wastewater, written commun., September 2007).

0

100

200

300

400

500

600

2005 2006 2005 2006 2005 2006 2005 2006

Total nitrogen Total phosphorus Total nitrogen Total phosphorus

Nutrient load, in tons

Blue River Indian Creek

WWTF discharge load

Total downstream load
Watershed Characteristics Affecting Water Quality in Johnson County Streams 83

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

1-Naphthol, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), 

recoverable, 

micrograms 

per liter (0.04)

2-Chloro2’,6’-diethylacetanilide, 

water, filtered, 

recoverable, 

micrograms 

per liter (0.01)

2-Chloro4-isopropylamino-6-aminos-triazine, 

water, filtered, 

recoverable, 

micrograms 

per liter (0.06)

2-Ethyl-6-

methylaniline, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.01)

3,4-Dichloroaniline, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.006)

4-Chloro-2-

methylphenol, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.005)

Acetochlor, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.006)

Alachlor, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.006)

Blue River at Kenneth Road

Number of samples 21 21 21 21 20 21 21 21

Number of detections 1 1 21 0 9 9 13 10

Maximum value < .088 .018 E .122 < .010 .096 E .010 .325 .731

Minimum value E .017 < .005 E .006 < .005 E .003 E .002 E .005 E .004

Mean value -- -- .047 -- -- -- .043 --

Median value -- -- .036 -- -- -- .006 --

Cedar Creek near DeSoto

Number of samples 21 21 22 21 21 21 22 22

Number of detections 1 0 21 0 18 0 9 3

Maximum value < .088 < .007 E .222 < .010 E .075 E .009 .401 < .008

Minimum value E .017 < .005 < .010 < .005 < .005 E .003 < .006 < .005

Mean value -- -- .077 -- .028 -- -- --

Median value -- -- .050 -- .029 -- -- --

Indian Creek at State Line Road

Number of samples 23 23 23 23 22 23 23 23

Number of detections 6 0 18 0 18 9 9 7

Maximum value < .088 < .007 E .092 < .010 .146 E .017 .202 .058

Minimum value E .006 < .005 E .002 < .005 < .005 E .004 < .006 < .005

Mean value -- -- .022 -- .036 -- -- --

Median value -- -- .017 -- .025 -- -- --

Kill Creek at 95th Street

Number of samples 25 25 26 25 24 25 25 25

Number of detections 3 0 26 0 4 0 11 5

Maximum value < .088 < .007 E .281 < .010 .014 < .006 1.11 .048

Minimum value E .003 < .005 E .010 < .005 E .003 < .005 < .006 < .005

Mean value -- -- .063 -- -- -- -- --

Median value -- -- .030 -- -- -- -- --

Mill Creek at Johnson Drive

Number of samples 21 21 22 21 21 21 22 22

Number of detections 5 0 18 0 13 9 8 7

Maximum value < .088 < .007 E .066 < .010 .513 E .018 .147 .037

Minimum value E .005 < .005 < .006 < .005 < .005 E .002 E .004 < .005

Mean value -- -- .027 -- .054 -- -- --

Median value -- -- .022 -- .014 -- -- --
84 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

alphaHCH-d6, 

surrogate, 

schedule 

2003, water, 

filtered, 

percent 

recovery

Atrazine, 

water, 

filtered, 

recoverable, 

micrograms 

per liter (0.04)

Azinphosmethyl oxygen 

analog, water, 

filtered, 

recoverable, 

micrograms 

per liter (0.12)

Benfluralin, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), 

recoverable, 

micrograms 

per liter 

(0.004)

Carbaryl, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), 

recoverable, 

micrograms 

per liter (0.06)

Chlorpyrifos, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.005)

Cyfluthrin, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.016)

Cypermethrin, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.014)

Blue River at Kenneth Road

Number of samples 21 21 21 21 21 21 21 21

Number of detections 21 21 0 3 10 0 0 0

Maximum value 116 3.90 < .070 < .010 E .315 < .005 < .053 < .070

Minimum value 58.6 .010 < .016 E .006 E .004 < .005 < .008 < .009

Mean value 89.7 .679 -- -- -- -- -- --

Median value 9.8 .184 -- -- -- -- -- --

Cedar Creek near DeSoto

Number of samples 21 22 21 22 22 22 21 21

Number of detections 21 21 0 2 10 1 0 0

Maximum value 109 4.69 < .075 < .010 E .219 < .010 < .053 < .090

Minimum value 77.5 < .035 < .016 E .006 E .008 < .005 < .008 < .009

Mean value 90.9 .767 -- -- -- -- -- --

Median value 91.8 .244 -- -- -- -- -- --

Indian Creek at State Line Road

Number of samples 22 23 23 23 23 23 23 23

Number of detections 22 22 0 13 16 0 0 0

Maximum value 130 .376 < .070 < .020 E .286 < .018 < .053 < .060

Minimum value 73.8 E .006 < .016 E .005 E .013 < .005 < .008 < .009

Mean value 90.7 .111 -- .010 .066 -- -- --

Median value 88.1 .062 -- .010 .041 -- -- --

Kill Creek at 95th Street

Number of samples 25 26 25 25 26 26 25 25

Number of detections 25 26 0 1 7 2 0 0

Maximum value 115 E 69 < .070 < .010 < 1.000 < .500 < .053 < .600

Minimum value 77.9 .021 < .016 E .006 E .003 < .005 < .008 < .009

Mean value 91.2 3.180 -- .010 -- -- -- --

Median value 89.9 .104 -- .010 -- -- -- --

Mill Creek at Johnson Drive

Number of samples 21 22 21 22 22 22 21 21

Number of detections 21 21 0 6 11 1 0 0

Maximum value 101 .240 < .070 < .020 E .120 .006 < .053 < .046

Minimum value 76.7 < .015 < .016 E .005 E .011 < .005 < .008 < .009

Mean value 89.0 .081 -- -- .043 -- -- --

Median value 87.8 .053 -- -- .041 -- -- --
Watershed Characteristics Affecting Water Quality in Johnson County Streams 85

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

DCPA, water, filtered 

(0.7 micron 

glass-bifer 

filter), recoverable, 

micrograms per 

liter

Desulfinyl 

fipronil, 

water, 

filtered, recoverable, 

micrograms per 

liter (0.012)

Desulfinylfipronil 

amide, water, filtered, 

recoverable, 

micrograms 

per liter 

(0.029)

Diazinon 

oxygen analog, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.006)

Diazinon, 

water, 

filtered, 

recoverable, micrograms 

per liter 

(0.005)

Diazinond10, 

surrogate, 

schedule 

2003, water, 

filtered, 

percent 

recovery

Dichlorvos, 

water, 

filtered, 

recoverable, micrograms 

per liter 

(0.013)

Dieldrin, 

water, 

filtered, 

recoverable, micrograms 

per liter 

(0.009)

Ethion 

monoxon, 

water, 

filtered, recoverable, 

micrograms 

per liter 

(0.021)

Blue River at Kenneth Road

Number of samples 21 21 21 16 21 21 21 21 21

Number of detections 2 11 3 0 5 21 2 0 0

Maximum value .004 < .012 < .029 < .040 .023 121 E .013 < .009 < .034

Minimum value E .002 E .003 E .004 < .006 < .005 75.8 E .001 < .005 < .002

Mean value -- .007 -- -- -- 106 -- -- --

Median value -- .006 -- -- -- 106 -- -- --

Cedar Creek near DeSoto

Number of samples 22 22 22 16 22 21 22 22 21

Number of detections 2 16 7 0 13 21 6 0 0

Maximum value < .003 .013 < .029 < .040 .308 195 < 1.00 < .009 < .034

Minimum value E .002 E .002 E .005 < .006 < .005 94.0 E .003 < .005 < .002

Mean value -- .007 -- -- .025 118 -- -- --

Median value -- .007 -- -- .006 110 -- -- --

Indian Creek at State Line Road

Number of samples 23 23 23 18 23 22 23 23 23

Number of detctions 11 21 10 1 13 22 12 0 0

Maximum value .005 .015 < .029 < .040 .131 232 E .557 < .022 < .034

Minimum value .001 E .003 E .002 E .005 < .005 89.6 E .005 < .005 < .002

Mean value -- .008 -- -- .032 124 .054 -- --

Median value -- .007 -- -- .020 116 .012 -- --

Kill Creek at 95th Street

Number of samples 25 25 25 19 26 25 26 25 25

Number of detections 4 14 6 0 1 25 1 9 0

Maximum value .005 < .012 < .029 < .010 < .500 135 < 1.00 .016 < .034

Minimum value .001 .001 E .006 < .006 < .005 89.0 < .012 E .003 < .002

Mean value -- .008 -- -- -- 107 -- -- --

Median value -- .007 -- -- -- 106 -- -- --

Mill Creek at Johnson Drive

Number of samples 22 22 22 17 22 21 22 22 21

Number of detections 7 19 4 0 12 21 10 0 0

Maximum value .005 .014 < .029 < .040 .080 127 < 1.000 < .009 < .034

Minimum value .001 E .003 E .001 < .006 < .005 95.6 E .003 < .005 < .002

Mean value -- .007 -- -- .024 109 -- -- --

Median value -- .006 -- -- .010 110 -- -- --
86 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

Fenamiphos 

sulfone, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.053)

Fenamiphos 

sulfoxide, 

water, filtered, 

recoverable, 

micrograms 

per liter (0.04)

Fipronil 

sulfide, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.013)

Fipronil sulfone, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.024)

Fipronil, water, filtered, 

recoverable, 

micrograms 

per liter 

(0.02)

Fonofos, water, filtered, 

recoverable, 

micrograms 

per liter 

(0.01)

Hexazinone, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.008)

Iprodione, 

water, 

filtered, 

recoverable, 

micrograms 

per liter (0.01)

Blue River at Kenneth Road

Number of samples 21 21 21 21 21 21 19 21

Number of detections 0 0 7 3 6 0 3 0

Maximum value < .053 < .040 < .013 < .024 < .016 < .005 < .026 < 1.42

Minimum value < .008 < .031 < .005 < .005 E .004 < .003 E .006 < .026

Mean value -- -- -- -- -- -- -- --

Median value -- -- -- -- -- -- -- --

Cedar Creek near DeSoto

Number of samples 21 21 22 22 22 22 20 21

Number of detections 0 0 10 6 18 0 0 0

Maximum value < .053 < 1.25 < .013 < .024 E .043 < .005 < .026 < 1.42

Minimum value < .008 < .031 E .003 < .005 E .008 < .003 < .013 < .026

Mean value -- -- -- -- .015 -- -- --

Median value -- -- -- -- .013 -- -- --

Indian Creek at State Line Road

Number of samples 23 23 23 23 23 23 22 23

Number of detections 0 0 21 13 23 0 1 1

Maximum value < .053 < .040 .016 E .025 E .082 < .005 < .026 < 1.42

Minimum value < .008 < .031 E .002 < .005 E .011 < .003 E .010 < .026

Mean value -- -- .007 .015 .037 -- -- --

Median value -- -- .006 .012 .031 -- -- --

Kill Creek at 95th Street

Number of samples 25 24 25 25 25 25 25 25

Number of detections 0 0 7 6 9 0 0 0

Maximum value < .053 < 1.25 < .013 < .024 < .016 < .005 < .026 < 1.42

Minimum value < .008 < .031 E .004 E .005 E .006 < .003 < .013 < .026

Mean value -- -- -- -- -- -- -- --

Median value -- -- -- -- -- -- -- --

Mill Creek at Johnson Drive

Number of samples 21 21 22 22 22 22 18 21

Number of detections 0 0 10 4 22 0 0 0

Maximum value < .053 < .040 .015 < .024 E .030 < .005 < .026 < 1.42

Minimum value < .008 < .031 E .004 < .005 E .006 < .003 < .013 < .026

Mean value -- -- -- -- .014 -- -- --

Median value -- -- -- -- .013 -- -- --
Watershed Characteristics Affecting Water Quality in Johnson County Streams 87

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

Isofenphos, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.006)

Malaoxon, 

water, filtered, 

recoverable, 

micrograms 

per liter (0.02)

Malathion, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.016)

Metalaxyl, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.0069)

Methidathion, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.004)

Methyl 

paraoxon, 

water, 

filtered, 

recoverable, 

micrograms 

per liter (0.01)

Methyl parathion, water, 

filtered (0.7-

micron glassfiber filter), 

recoverable, 

micrograms 

per liter (0.008)

Metolachlor, 

water, 

filtered, recoverable, 

micrograms 

per liter 

(0.01)

Blue River at Kenneth Road

Number of samples 21 21 21 21 21 21 21 21

Number of detections 0 0 0 1 0 0 0 20

Maximum value < .011 < .039 < .027 < .025 < .009 < .030 < .015 1.68

Minimum value < .003 < .008 < .027 < .005 < .006 < .019 < .006 < .006

Mean value -- -- -- -- -- -- -- .242

Median value -- -- -- -- -- -- -- .042

Cedar Creek near DeSoto

Number of samples 21 21 22 21 21 21 22 22

Number of detections 0 0 0 5 0 0 0 22

Maximum value < .011 < .150 < .027 E .053 < .009 < .030 < .015 .431

Minimum value < .003 < .008 < .027 < .005 < .006 < .019 < .006 E .006

Mean value -- -- -- -- -- -- -- .103

Median value -- -- -- -- -- -- -- .057

Indian Creek at State Line Road

Number of samples 23 23 23 23 23 23 23 23

Number of detections 0 0 8 0 0 0 0 21

Maximum value < .011 < .039 < .027 < .025 < .030 < .030 < .015 .106

Minimum value < .003 < .008 E .010 < .005 < .006 < .019 < .006 E .006

Mean value -- -- -- -- -- -- -- .037

Median value -- -- -- -- -- -- -- .024

Kill Creek at 95th Street

Number of samples 25 25 25 25 25 25 25 26

Number of detections 0 0 0 0 0 0 0 17

Maximum value < .011 < .039 < .027 < .010 < .020 < .030 < .015 < .500

Minimum value < .003 < .008 < .027 < .005 < .006 < .019 < .006 E .003

Mean value -- -- -- -- -- -- -- .030

Median value -- -- -- -- -- -- -- .010

Mill Creek at Johnson Drive

Number of samples 21 21 22 21 21 21 22 22

Number of detections 0 0 3 1 0 0 0 20

Maximum value < .011 < .039 < .027 < .017 < .009 < .030 < .015 .069

Minimum value < .003 < .008 E .011 < .005 < .006 < .019 < .006 .008

Mean value -- -- -- -- -- -- -- .024

Median value -- -- -- -- -- -- -- .022
88 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, 

northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

Metribuzin, 

water, 

filtered, recoverable, 

micrograms 

per liter 

(0.012)

Myclobutanil, water, 

filtered, recoverable, 

micrograms 

per liter 

(0.01)

Pendimethalin, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), recoverable, micrograms per liter 

(0.012)

Phorate 

oxygen analog, 

water, filtered, 

recoverable, 

micrograms 

per liter (0.027)

Phorate, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), 

recoverable, 

micrograms 

per liter (0.04)

Phosmet 

oxygen analog, 

water, filtered, 

recoverable, 

micrograms 

per liter 

(0.0027)

Phosmet, 

water, 

filtered, recoverable, 

micrograms 

per liter 

(0.0079)

Prometon, 

water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.01)

Blue River at Kenneth Road

Number of samples 21 21 21 21 21 15 17 21

Number of detections 4 3 2 0 0 0 0 21

Maximum value .059 < .033 < .022 < .105 < .055 < .055 < .008 .165

Minimum value < .006 E .006 E .013 < .027 < .011 < .051 < .008 .008

Mean value -- -- -- -- -- -- -- .027

Median value -- -- -- -- -- -- -- .019

Cedar Creek near DeSoto

Number of samples 22 21 22 21 22 15 17 22

Number of detections 2 7 1 0 0 0 0 22

Maximum value .028 < .033 < .022 < .105 < .055 < .055 < .008 .143

Minimum value < .006 E .007 E .016 < .027 < .011 < .051 < .008 E .009

Mean value -- -- -- -- -- -- -- .031

Median value -- -- -- -- -- -- -- .016

Indian Creek at State Line Road

Number of samples 23 23 23 23 23 19 20 23

Number of detections 0 14 12 0 0 0 0 21

Maximum value < .028 < .270 E .074 < .105 < .055 < .055 < .008 .176

Minimum value < .006 < .008 E .018 < .027 < .011 < .051 < .008 < .005

Mean value -- .034 .033 -- -- -- -- .042

Median value -- .020 .025 -- -- -- -- .031

Kill Creek at 95th Street

Number of samples 25 25 25 25 25 17 19 26

Number of detections 3 0 3 0 0 0 0 24

Maximum value < .035 < .033 < .022 < .105 < .055 < .055 < .008 < .500

Minimum value E .005 < .008 E .013 < .027 < .011 < .051 < .008 E .006

Mean value -- -- -- -- -- -- -- .045

Median value -- -- -- -- -- -- -- .017

Mill Creek at Johnson Drive

Number of samples 22 21 22 21 22 16 17 22

Number of detections 0 4 6 0 0 0 0 21

Maximum value < .028 < .033 .073 < .105 < .055 < .055 < .008 .163

Minimum value < .006 E .007 E .020 < .027 < .011 < .051 < .008 .011

Mean value -- -- -- -- -- -- -- .044

Median value -- -- -- -- -- -- -- .032
Watershed Characteristics Affecting Water Quality in Johnson County Streams 89

Table 15. Results of analysis of pesticides in discrete samples collected at five continuous water-quality monitoring sites in Johnson County, northeast Kansas, October 2002 through January 2006.—Continued

[( ), laboratory reporting level; <, less than; E, estimated; --, not calculated because more than half of the values were less than the detection limit]

Monitoring site 

(fig. 1) and summary 

statistics

Prometryn, 

water, filtered, 

recoverable, 

micrograms 

per liter

Propyzamide, 

water, filtered 

(0.7-micron 

glass-fiber 

filter), recoverable, micrograms per liter 

(0.0059)

Simazine, 

water, filtered, 

recoverable, 

micrograms per 

liter (0.006)

Tebuthiuron, 

water, filtered 

(0.7-micron 

glass-fiber filter), 

recoverable, 

micrograms per 

liter (0.016)

Terbufos 

oxygen analog 

sulfone, water, 

filtered, 

recoverable, 

micrograms per 

liter (0.018)

Terbuthylazine, water, 

filtered, 

recoverable, 

micrograms 

per liter 

(0.0083)

Trifluralin, water, 

filtered 

(0.7-micron 

glass-fiber filter), 

recoverable, 

micrograms per 

liter (0.006)

Blue River at Kenneth Road

Number of samples 21 21 21 21 21 21 21

Number of detections 1 0 19 0 0 0 7

Maximum value .009 < .004 .200 < .021 < .068 < .010 < .009

Minimum value < .005 < .004 E .004 < .016 < .045 < .008 E .002

Mean value -- -- .034 -- -- -- --

Median value -- -- .009 -- -- -- --

Cedar Creek near DeSoto

Number of samples 21 22 22 22 21 21 22

Number of detections 0 0 21 3 0 2 5

Maximum value < .006 < .004 .742 .020 < .068 < .025 < .009

Minimum value < .005 < .004 < .012 E .007 < .045 E .005 E .00

Mean value -- -- .150 -- -- -- --

Median value -- -- .079 -- -- -- --

Indian Creek at State Line Road

Number of samples 23 23 23 23 23 23 23

Number of detections 0 0 13 1 0 4 15

Maximum value < .006 < .006 4.64 < .045 < .068 .026 .020

Minimum value < .005 < .004 < .005 E .006 < .011 E .007 E .006

Mean value -- -- .219 -- -- -- .011

Median value -- -- .010 -- -- -- .009

Kill Creek at 95th Street

Number of samples 25 25 24 26 25 24 25

Number of detections 0 0 10 1 0 2 7

Maximum value < .006 < .004 .039 < .026 < .068 < .010 .023

Minimum value < .005 < .004 E .002 E .006 < .045 E .003 E .004

Mean value -- -- -- -- -- -- --

Median value -- -- -- -- -- -- --

Mill Creek at Johnson Drive

Number of samples 21 22 22 22 21 21 22

Number of detections 1 0 15 12 0 3 8

Maximum value .009 < .005 .081 .066 < .068 .037 .012

Minimum value < .005 < .004 < .005 E .012 < .045 < .008 E .003

Mean value -- -- .018 .026 -- -- --

Median value -- -- .012 .018 -- -- --
90 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

Figure 34. Constituent yields and impervious surface area at five water-quality monitoring sites in 

Johnson County, Kansas, 2005–06.

0

100

200

300

400

500

600

700

800

Suspended-sediment yield, in tons per

square mile per year

0

20

40

60

80

100

120

140

160

180

Chloride yield, in tons per square mile per year

2005

2006

2005

2006

2005

2006

Kill Creek at 95th Street

Cedar Creeknear DeSoto

Blue River at Kenneth Road

Kill Creek 

at 95th Street Cedar Creek

near DeSoto

Blue River at 

Kenneth Road

Mill Creek at

Johnson Drive

Indian Creek at

State Line Road

Mill Creek at

Johnson Drive

Indian Creek at

State Line Road

Kill Creek 

at 95th Street Blue River at 

Kenneth Road

Cedar Creek

near DeSoto Mill Creek at

Johnson Drive

Indian Creek at

State Line Road

0

50,000

100,000

150,000

200,000

250,000

0 5 10 15 20 25

Percentage impervious surface area

Escherichia coli bacteria yield, in billion colonies

per square mile per year
Summary and Conclusions 91

Most measured contaminants in Johnson County 

streams, including suspended sediment, indicator bacteria, 

some nutrients, and most pesticides, originate primarily from 

nonpoint sources, primarily overland flow during storm runoff. 

Each can be expected to increase in concentration substantially during storm runoff and decrease again some time after 

streamflow recedes. Although concentrations in the water 

column decrease following storms, contaminants can remain 

in the stream and accumulate in streambed sediment (Lee and 

others, 2005).

Atmospheric deposition may be another important nonpoint source for some water-quality constituents in Johnson 

County streams. Nationwide, the most common air pollutants 

that degrade water quality are nitrogen compounds, mercury 

and other metals, pesticides, and industrial emissions such 

as dioxins, furans, polycyclic aromatic hydrocarbons (PAHs) 

and polychlorinated biphenyls (PCBs) (U.S. Environmental 

Protection Agency, 2004a). In 2004, an estimated 12 lb/acre of 

nitrogen from nitrate and ammonium was deposited in precipitation over eastern Kansas (National Atmospheric Deposition 

Program, 2005).

WWTFs are a primary point source of some contaminants 

in Johnson County streams, and their discharges affect streams 

most during base flow (Lee and others, 2005). Generally, 

wastewater discharges affect receiving streams by introducing oxygen-demanding substances, pathogens, nutrients, and 

organic chemicals to the stream (U.S. Environmental Protection Agency, 2004b). Oxygen-demanding substances, such as 

organic matter and ammonia, consume natural supplies of dissolved oxygen in the stream, and can result in insufficient supplies to support fish and other aquatic life. Dissolved oxygen 

at the Indian Creek monitoring site, which is most affected by 

WWTFs discharge, was less than the KDHE aquatic-life criterion of 5.0 mg/L about 20 percent of the time and more than 

any other site (fig. 9A), indicating that WWTF discharge likely 

was affecting aquatic life at that site. E. coli bacteria densities 

were largest at the Indian Creek site compared to other sites 

(fig. 26). In addition, nutrients including total phosphorus 

were largest at that site (table 14).

Contaminants in streams that originate from WWTFs, 

including some nutrients and wastewater compounds (Lee 

and others, 2005), generally decrease during storm runoff as a 

result of dilution. Exceptions may occur during storms when 

large volumes of water exceed the WWTF’s treatment capacity, resulting in temporary discharge of effluent that has not 

been fully treated. Although WWTFs contribute a relatively 

small portion of the total load of water-quality constituents, 

the primary concern to aquatic environments is large concentrations during base and normal flow that may extend for long 

periods of time.

Although urbanization falls into the general category of 

human activity, additional types of human activities also can 

affect water quality. Physical alterations (such as channelization, impoundments, irrigation), chemical alterations (such 

as application of fertilizers and pesticides, septic systems), 

and biological alterations (such as forest and agricultural 

management, import of exotic species) change the hydrologic 

cycle and water-quality characteristics of streams (Peters and 

Meybeck, 2000). One example of a human activity in Johnson 

County that is not exclusively associated with urbanization but 

has a notable effect on water quality is the seasonal application of pesticides. The largest concentrations of all pesticides 

occurred in samples collected during storm runoff, usually in 

the spring.

Johnson County has developed a stormwater management 

plan that describes implementation of BMPs to reduce adverse 

effects of stormwater runoff on water quality as required by 

the NPDES program. BMPs can improve stormwater quality 

by reducing or removing sediment, metals, bacteria, nutrients, organic compounds and other substances. BMPs can be 

nonstructural, such as maintaining native areas and flood-plain 

vegetation for filtering runoff, or structural, such as constructing ponds, wetlands, and infiltration devices (Mid-America 

Regional Council and American Public Works Association, 

2003). In addition, TMDLs developed by the Kansas Department of Health and Environment describe recommended 

actions to address water-quality impairments. Activities 

recommended in Johnson County TMDLs include installing 

grass buffer strips, maintaining riparian areas, and reducing 

peak streamflows and associated sediment and nutrient loads 

(Kansas Department of Health and Environment, 2007), as 

well as upgrading nutrient treatment in wastewater facilities 

and repairing faulty septic systems (Kansas Department of 

Health and Environment, 2006b). Implementation of BMPs 

is expected to affect water quality of Johnson County streams 

over time.

Summary and Conclusions

Johnson County is one of the most rapidly developing 

counties in Kansas. According to the U.S. Census Bureau, 

population increased by about 90 percent in the last 25 years, 

from 270,269 in 1980 to an estimated 516,731 in 2006. Population growth and expanding urban land use affect the quality 

of county streams, which are important for human and environmental health, water supply, recreation, and aesthetic value. 

Urbanization generally affects streams by altering hydrology, 

geomorphology, chemistry, and biology.

Continuous water-quality monitors and streamflowgaging stations were installed on five different streams in 

Johnson County, northeast Kansas, to estimate water-quality 

constituent concentrations, densities, loads, and yields using 

continuous in-stream sensor measurements and to characterize differences relative to hydrologic conditions, contributing drainage area, land use, point and nonpoint sources, and 

human activity. Monitoring sites were located as far downstream as possible in the largest watersheds in the county and 

designed to represent urban, urbanizing, and nonurban land 

uses. Two of the sites, Cedar Creek near DeSoto and Mill 

Creek at Johnson Drive, were installed in October 2002, and 
92 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

three sites, Blue River at Kenneth Road, Indian Creek at State 

Line Road, and Kill Creek at 95th Street, were installed in 

March 2004. All sites were operated through December 2006.

Each site was equipped with a water-quality monitor 

that provided continuous in-stream measurements of specific 

conductance, pH, water temperature, turbidity, and dissolved 

oxygen. The data are available in real time on USGS Web 

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

http://waterdata.usgs.gov/ks/nwis/). In addition to continuous 

monitoring, discrete water samples were collected manually 

from each site. Samples were analyzed for nutrients, indicator 

bacteria, sediment, pesticides, and other constituents. Regression analysis was used to develop relations between the continuous sensor measurements, streamflow, time, and discretely 

sampled constituent concentrations. Continuous (hourly) 

constituent concentrations were estimated using equations 

from the regression models. Constituent loads and yields were 

estimated from continuous concentration estimates, continuous 

streamflow data, and respective drainage-basin area. Most siteto-site comparisons were made using the period March 2004 

through December 2006 when monitors were operating at all 

five sites simultaneously. Estimated annual loads and yields 

were evaluated for January 2005 through December 2006.

In-stream measurements of streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen (DO) varied with precipitation, season, time of day, and 

contributing sources. Hourly streamflow ranged from less than 

1 ft3/s in Kill Creek (2004, 2005, and 2006) and the Blue River 

(2005 and 2006) to 19,200 ft3/s in the Blue River (2004). The 

largest median streamflow from March 2004 through 2006 

occurred in Indian Creek, which is the second largest drainage basin (63.1 mi2

) and the most urban of the five monitored 

basins. Kill Creek, the smallest and least urban of the monitored basins (48.6 mi2

), generally had the smallest streamflow 

except during base flows when Blue River streamflow was 

smallest. Annual differences in streamflow can be attributed 

to differences in precipitation. Average annual precipitation in 

2004 and 2005 was close to the historical mean annual precipitation of 40 in. Precipitation in 2006 was less than normal, 

ranging from about 30 to 35 in.

Rapid changes in specific conductance and turbidity 

associated with changes in streamflow occurred in Johnson 

County streams. From March 2004 through 2006, specific 

conductance was nearly always largest at the Indian Creek 

site, followed by the Mill Creek site, the two most urban sites 

and the two sites with the largest WWTF contribution. Both 

sites showed sharp increases in specific conductance during 

15 percent of the time, as a result of road-salt application. 

Turbidity ranged from less than 2 FNUs at all sites annually 

to about 2,000 FNUs at the Cedar and Mill Creek sites. Mill 

Creek is in the most rapidly developing of the monitored 

watersheds, which may result in increased sediment runoff in 

the basin contributing to elevated turbidity. The Indian Creek 

site had the smallest turbidity most of the time because of the 

high clarity of WWTF discharge. Most of the time, pH and 

DO remained lower and water temperature higher at the Indian 

Creek site compared to the other Johnson County monitoring sites because of WWTF discharges. From March 2004 

through December 2006, DO concentrations were less than 

the Kansas aquatic-life-support criterion of 5.0 mg/L less than 

10 percent of the time at all sites except Indian Creek, which 

had DO concentrations less than the criterion about 15 percent 

of the time.

Continuous data for three water-quality constituents 

(suspended sediment, chloride, and E. coli bacteria) were 

evaluated thoroughly in this report. These particular constituents were selected for additional discussion because they 

represent three major categories of concern in Johnson County 

streams (sediment, major ions, and bacteria) that have been 

identified as sources of water-quality impairment by KDHE. 

Regression models for nutrients, a fourth category of concern in Johnson County, generally had more variability than 

models for suspended sediment, chloride, and E. coli bacteria 

because of the larger variability in sources, fate, and transport 

in streams. Generally for most constituents, models for the less 

urban sites (Blue River and Kill Creek) contained less variability than models for the more urban sites (Indian and Mill 

Creeks). This is because water quality in urban areas is more 

complex because of multiple sources and often altered pathways. Sediment is statistically related to other water-quality 

constituents, and these relations have potential implications 

for implementation of best management practices (BMPs) in 

that if sediment concentrations decrease, concentrations of 

sediment-associated constituents such as suspended solids, 

some nutrients, and bacteria also will decrease.

Estimated concentrations of suspended sediment in 

2005–06 ranged from a minimum of less than 3 mg/L at all 

five monitoring sites to a maximum of 4,600 mg/L at the 

Cedar Creek site in 2005 and the Blue River site in 2006. 

From March 2004 through December 2006, suspendedsediment concentration was nearly always largest at the Mill 

Creek site. The Mill Creek watershed is undergoing rapid 

development that likely is contributing to larger sustained 

sediment concentrations. About 70 percent of the time, the 

smallest sediment concentration occurred at the Indian Creek 

site, likely because most of the streamflow originated from 

treated WWTF discharge just upstream from the monitoring 

site. Estimated annual suspended-sediment loads and yields 

were largest annually at the Indian Creek site and annual loads 

were smallest at the Kill Creek site. At least 90 percent of the 

total annual load in 2005–06 at all five sites occurred during 

less than 2 percent of the time, generally associated with large 

storm runoff. The streamflow that was exceeded less than 

2 percent of the time at the monitoring sites ranged from about 

250 ft3/s at the Cedar and Kill Creek sites to about 1,000 ft3/s 

at the Indian Creek site. About 50 percent of the 2005 sediment load at the Blue River site occurred during a 3-day storm, 

the equivalent of less than 1 percent of the time. The implication is that management practices designed to control sediment 

during small streamflows will have minimal effect on annual 

loads. During the 3- to 4-year period of record for the five 

monitoring sites, streamflow has only slightly exceeded the 
Summary and Conclusions 93

estimated 2-year peak streamflow at all sites except the Cedar 

and Kill Creek sites where streamflow has not exceeded the 

2-year peak since monitoring began. Therefore, sediment load 

contributions when the 2-year streamflow is exceeded have not 

been well documented but are expected to be substantial.

Chloride concentrations from March 2004 through 

December 2006 were largest at the Indian and Mill Creek 

sites, the two most urban monitoring sites which also are most 

affected by road-salt runoff and WWTF discharges. Estimated 

chloride concentrations ranged from about 5 mg/L at the 

Cedar Creek site in 2006 to 1,500 mg/L at the Indian Creek 

site in 2006. About 10 percent of the time, the Indian and Mill 

Creek sites were noticeably affected by increased chloride 

concentrations as a result of road-salt runoff, while the Blue 

River and Kill Creek sites experienced no major effects from 

road-salt application. At the Indian Creek site during 2005–06, 

there was a 50-percent probability of chloride concentration 

exceeding the 250-mg/L USEPA Secondary Drinking-Water 

Regulation about 8 percent of the time, and exceeding the 860-

mg/L KDHE acute aquatic-life criterion less than 1 percent 

of the time. The effect of accumulated road salt on ground 

water and base flow throughout the remainder of the year is 

unknown. About 50 percent of the total chloride load during 

2005–06 occurred in less than 10 percent of the time at all five 

monitoring sites. Two chloride runoff occurrences in January–

February 2005 accounted for 19 percent of the total chloride 

load in Indian Creek in 2005.

From March 2004 through December 2006, E. coli

density at the Indian Creek site was nearly always largest 

with a median density more than double that of any other 

monitoring site, and at least 15 times the density at the Blue 

River site. The KDHE primary contact criterion for recreation (262 col/100 mL) was exceeded about 65 percent of 

the time at the Indian Creek site, and the secondary criterion (2,358 col/100 mL) was exceeded about 10 percent of 

the time. At the other monitoring sites, the primary contact 

criterion was exceeded between about 8 and 25 percent of the 

time, and the secondary contact criterion was exceeded less 

than 5 percent of the time. The Blue River and Cedar Creek 

sites had the smallest bacteria densities most of the time. 

During 2005–06, more than 90 percent of the total E. coli

bacteria load at the Cedar Creek site occurred in less than 1 

percent of the time, generally associated with storm runoff, 

compared to the Indian Creek site where about 80 percent of 

the total E. coli load occurred during less than 1 percent of 

the time. The largest annual bacteria yields occurred at the 

Indian Creek site as well. Potential urban sources of bacteria 

in Indian Creek include leaky sewer lines, pet waste, wildlife, 

WWTF discharges and bypasses, and unauthorized dumping. 

Potential nonurban sources of bacteria in less urban watersheds include livestock, leaky septic systems, and wildlife. 

Fecal coliform loads originating from two WWTFs on Indian 

Creek contributed less than 3 percent of the downstream 

estimated fecal coliform bacteria load at the Indian Creek 

monitoring site. When fecal coliform bacteria load from the 

Blue River WWTF, which discharges just downstream from 

the Blue River monitoring site, was added to the total load at 

the Blue River monitoring site, less than 1 percent of the total 

downstream Blue River fecal coliform bacteria load originated 

from the WWTF. More than 97 percent of the fecal coliform 

bacteria load in Indian Creek and the Blue River originated 

from nonpoint sources.

Although nutrients originated from both point and 

nonpoint sources, the largest total nitrogen concentrations 

in discrete samples generally occurred at the Indian Creek 

monitoring site during streamflows less than 200 ft3/s and 

were primarily in the form of nitrate, indicating that WWTFs 

were likely the primary source. Total nitrogen discharged from 

the two Indian Creek WWTFs accounted for about 65 percent 

of estimated total nitrogen load at the downstream Indian 

Creek monitoring site in 2005 and 90 percent of the downstream estimated total nitrogen load in 2006 when stormwater 

runoff was less. Total phosphorus load from the Indian Creek 

WWTFs was at least 90 percent of the total phosphorus load 

at the downstream monitoring site in 2005 and 2006. Larger 

concentrations of nutrients in stormwater at nonurban sites, 

including the Blue River and Cedar and Kill Creek sites, indicated the nonpoint sources are predominant. However, downstream from the Blue River monitoring site where the WWTF 

discharges to the river, about 40 percent of the total nitrogen 

load in 2005 and 70 percent of the total nitrogen load in 2006 

originated from the WWTF. One-fourth (in 2005) to one-half 

(in 2006) of the downstream total phosphorus load in the Blue 

River originated from WWTF discharges.

Regression models for providing continuous estimates 

of pesticides in Johnson County streams were not developed 

because no continuously measured explanatory variables were 

found to be significant. Mixed land uses and complex sources 

and pathways in Johnson County watersheds likely contributed to large statistical variability in the relations between 

variables. Discrete-sample analysis indicated that many of the 

same pesticides frequently found nationwide also were most 

common in Johnson County streams. Atrazine (an herbicide 

often used in crop production) and its degradates were common at all monitoring sites. Prometon (an extensively used 

urban herbicide) also was detected in the majority of samples 

at each site. Metolachlor (a common agricultural herbicide) 

was found in the majority of samples at all sites except Kill 

Creek, where it was detected in about one-half of the samples. 

Simazine (another extensively used herbicide usually associated with urban uses) was found in samples from all five sites 

but was detected most frequently and generally in the largest 

concentrations in samples from the Cedar Creek site. The 

largest concentrations of all pesticides occurred in samples 

collected during storm runoff, usually in the spring.

Water-quality conditions at the five monitoring sites 

generally depended on hydrologic conditions, land use, percentage of urbanization, and relative contributions from point 

and nonpoint constituent sources. Precipitation, primarily the 

amount, frequency, and intensity of rainfall, is the fundamental factor contributing to streamflow and affecting transport 

of nonpoint contaminants. WWTF discharge is the primary 
94 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas

source of streamflow during base flow. In Johnson County, 

generally as impervious surface area increased, so did total 

annual yield for many water-quality constituents in 2005 and 

2006. Most contaminants in Johnson County streams, including suspended sediment, indicator bacteria, some nutrients, 

and most pesticides, originate primarily from nonpoint 

sources, primarily overland flow during storm runoff.

Continuous in-stream water-quality monitoring of Johnson County streams provided the foundation for a comprehensive evaluation of variability and chemical-loading characteristics for water-quality constituents including suspended 

sediment, selected major ions, indicator bacteria, and some 

nutrient species. The results presented in this report may be 

used to better understand constituent concentration and load 

fluctuations, range, and variability during changing seasonal 

and flow conditions and to assess water-quality conditions 

relative to TMDLs, NPDES requirements, and water-quality 

standards. The baseline information also will be useful for 

evaluating future changes in land use and effectiveness of 

implemented BMPs.

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Appendix
100 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Appendix 1. Water-quality constituents, descriptions, and criteria used to evaluate stream conditions in Johnson County, northeast Kansas. [mg/L, milligrams per liter or parts per million; col/100 mL, colonies per 100 milliliters of water; mg/L, micrograms per liter or parts per billion; FNU, formazine nephelometric units; SDWR1, Secondary Drinking-Water Regulation (nonenforceable); MCL2, Maximum Contaminant Level (enforceable); C, Celsius; F, Fahrenheit;] Constituent Description Criteria or guidelines Criteria or guideline source Directly measured water-quality constituents Specific conductance (SC) A measure of the capacity of water to conduct an electrical current; a function of the types and quantities of dissolved substances in water (Radtke and others, 2005). As concentra- tions of dissolved ions increase, specific conductance of the water increases. None Useful indicator for dissolved substances in water. pH A measure of the effective hydrogen-ion concentration or activ- ity (Wilde and others, 2005); measure of the acidity (pH less than 7) or alkalinity (pH greater than 7) of a solution; a pH of 7 is neutral. Not less than 6.5 and not more than 8.5 standard units Aquatic-life-support use criteria (Kansas Department of Health and Environment, 2005). Water temperature (WT) Has an important effect on the density of water, the solubil- ity of constituents in water, pH, specific conductance, the rate of chemical reactions, and biological activity in water (Wilde, 2006). Narrative criteria A discharge from an artificial source shall not elevate the tem- perature above 32 degrees C (90 degrees F) and not raise the temperature more than 3 degrees C above natural conditions. Useful to determine chemical treatment of drinking water (Kansas Department of Health and Environment, 2005). Turbidity (FNU) Reduced clarity of water generally caused by suspended par- ticles; measured by quantifying the amount of light scattered by particles in the water (Anderson, 2005). 15.5 FNU Recommended nutrient criteria for streams in Ecoregion IX, Subecoregion 40 (U.S. Environmental Protection Agen- cy, 2003b). Dissolved oxygen (DO) Oxygen dissolved in surface water is related primarily to atmo- spheric reaeration and photosynthetic activity of aquatic plants (Lewis, 2006). It is a significant factor in chemical reactions in water and the survival of aquatic organisms. Not less than 5.0 mg/L Aquatic-life-support use criteria (Kansas Department of Health and Environment, 2005). Laboratory-analyzed and regression-estimated water-quality constituents Suspended-sediment concentration (SSC) Particles of rock, sand, soil, and organic material in suspen- sion in the water column. Suspended sediment, particularly sediment composed of fine material like silt and clay, gives water a muddy appearance and provides attachment sites for accumulation and transport of nutrients, bacteria, and other contaminants. Narrative criteria Suspended solids added by artificial sources shall not interfere with aquatic life (Kansas Department of Health and Environ- ment, 2005). Total suspended solids (TSS) Different from suspended sediment in the way that the sample is collected and analyzed. Narrative criteria Suspended solids added by artificial sources shall not interfere with aquatic life (Kansas Department of Health and Environ- ment, 2005). Dissolved solids (DS) Amount of minerals, such as salt, that are dissolved in water; 

amount of dissolved solids is an indicator of salinity or hardness (Hem, 1992).

500 mg/L SDWR for finished drinking water (U.S. Environmental Protection Agency, 2003a).
Appendix 101

Appendix 1. Water-quality constituents, descriptions, and criteria used to evaluate stream conditions in Johnson County, northeast Kansas.—Continued[mg/L, milligrams per liter or parts per million; col/100 mL, colonies per 100 milliliters of water; mg/L, micrograms per liter or parts per billion; FNU, formazine nephelometric units; SDWR1, Secondary Drinking-Water Regulation (nonenforceable); MCL2, Maximum Contaminant Level (enforceable); C, Celsius; F, Fahrenheit;]

Constituent Description Criteria or guidelines Criteria or guideline source

Laboratory-analyzed and regression-estimated water-quality constituents—Continued

Alkalinity (Alk) The capacity for solutes in the water to react with and neutralize 

acid (Hem, 1992). Natural sources of alkalinity are limestone and decomposition of organic matter. Alkalinity is important in determining a stream’s ability to neutralize acidic pollution from rainfall or wastewater.

None No numeric criteria. 

Bicarbonate (HCO3) Bicarbonate is one of the solutes in the water that buffers the pH 

of natural waters to react with and neutralize acid. Sources of bicarbonate are limestone and decomposition of organic matter. Bicarbonate is important in determining a stream’s ability to neutralize acidic pollution from rainfall or wastewater (Hem, 1992).

None No numeric criteria. 

Hardness (CaCO3) The hardness of water is commonly expressed in an equivalent 

quantity of calcium carbonate that represents the majors cations found in water including calcium, sodium, potassium, and magnesium. Sources of hardness are from all different rock types (Hem, 1992).

None No numeric criteria. 

Calcium (Ca) A cation present in nearly all natural waters, although concentrations vary; present in nearly all rocks and soils and 

frequently is the dominant cation in natural waters. Common source of calcium in water is from dissolution of limestone (Hem, 1992).

None No numeric criteria. 

Sodium (Na) A cation present in nearly all natural waters, although concentrations vary; present in nearly all rocks and soils. Common 

sources of sodium in water are dissolution of clay and feldspar minerals (Hem, 1992).

20 mg/L Drinking Water Effects Level; non-enforceable advisory 

level for persons on low sodium diets; taste threshold of 30–60 milligrams per liter (U.S. Environmental Protection Agency, 2003a).

Chloride (Cl) Present in nearly all natural waters, although concentrations are 

normally low. Can originate from natural evaporate deposits of salt and from past oil and gas brine solutions (Hem, 1992).

250 mg/L SDWR for finished drinking water (U.S. Environmental Protection Agency, 2003a).860 mg/L Acute-aquatic-life criteria (Kansas Department of Health and 

Environment, 2005).

Sulfate (SO4) Contributes to the dissolved solids in water and can come from 

irrigation return flow, which increases concentrations from evapotranspiration. Sulfate originates from evaporate deposits such as gypsum and the oxidation of sulfide minerals such as pyrite (Hem, 1992).

250 mg/L SDWR for finished drinking water (USEPA, 2003a).
102 Estimation of Constituent Concentrations, Loads, and Yields in Streams of Johnson County, Northeast Kansas Appendix 1. Water-quality constituents, descriptions, and criteria used to evaluate stream conditions in Johnson County, northeast Kansas.—Continued [mg/L, milligrams per liter or parts per million; col/100 mL, colonies per 100 milliliters of water; mg/L, micrograms per liter or parts per billion; FNU, formazine nephelometric units; SDWR1, Secondary Drinking-Water Regulation (nonenforceable); MCL2, Maximum Contaminant Level (enforceable); C, Celsius; F, Fahrenheit;] Constituent Description Criteria or guidelines Criteria or guideline source Laboratory-analyzed and regression-estimated water-quality constituents—Continued Sulfate (SO4

) 1,000 mg/L Livestock watering criteria (Kansas Department of Health and 

Environment, 2005).

Fluoride (F) Present in nearly all natural waters, although concentrations are 

normally less than 1 mg/L (Hem, 1992). Typically is present in mineral grains in rocks. Fluoride is added to many drinkingwater supplies to assist in making teeth harder.

4.0 mg/L MCL for fluoride in finished drinking water (USEPA, 2003a).1.0 mg/L Irrigation criterion (Kansas Department of Health and Environment, 2005).2.0 mg/L Livestock watering criteria and domestic water supply (Kansas 

Department of Health and Environment, 2005).

Total nitrogen (TN) A nutrient necessary for growth and reproduction. Large inputs 

to the aquatic environment can cause excessive algal growth. When algal blooms die, concentrations of dissolved oxygen are depleted, which can stress aquatic organisms and may cause taste-and-odor problems in water supplies.

0.855 mg/L as 

nitrogen

Recommended nutrient criteria for streams in Ecoregion IX, 

Subecoregion 40 (U.S. Environmental Protection Agency, 2003b).

Total organic 

nitrogen (TON)

The component of total nitrogen that is organic; usually originates from soils, plant and animal materials, and untreated 

wastewater.

0.625 mg/L as 

nitrogen

Recommended nutrient criteria for streams in Ecoregion IX, 

Subecoregion 40 (U.S. Environmental Protection Agency, 2003b).

Total phosphorus (TP) A nutrient necessary for growth and reproduction. Large inputs 

to the aquatic environment can cause excessive algal growth. When algal blooms die, concentrations of dissolved oxygen are depleted, which can stress aquatic organisms and may cause taste-and-odor problems in water supplies.

0.0925 mg/L as 

phosphorus

Recommended nutrient criteria for streams in Ecoregion IX, 

Subecoregion 40 (U.S. Environmental Protection Agency, 2003b).

Escherichia coli

bacteria (ECB)

Presence in surface water indicates fecal contamination by 

warmblooded mammals and possibly indicates the presence of other organisms that could cause disease.

160 col/100 mL Primary contact (swimming in swim beach) recreation criterion 

from April to October for a geometric mean of at least five samples in 30-day period (Kansas Department of Health and Environment, 2005).

262 col/100 mL Primary contact (swimming in public water or public access) 

recreation criterion from April to October for a geometric mean of at least five samples in 30-day period (Kansas Department of Health and Environment, 2005).

427 col/100 mL Primary contact (swimming in private water, no access) recreation criterion from April to October for a geometric mean of 

at least five samples in 30-day period (Kansas Department of Health and Environment, 2005).
Appendix 103

Appendix 1. Water-quality constituents, descriptions, and criteria used to evaluate stream conditions in Johnson County, northeast Kansas.—Continued[mg/L, milligrams per liter or parts per million; col/100 mL, colonies per 100 milliliters of water; mg/L, micrograms per liter or parts per billion; FNU, formazine nephelometric units; SDWR1, Secondary Drinking-Water Regulation (nonenforceable); MCL2, Maximum Contaminant Level (enforceable); C, Celsius; F, Fahrenheit;]

Constituent Description Criteria or guidelines Criteria or guideline source

Laboratory-analyzed and regression-estimated water-quality constituents—Continued

Escherichia coli

bacteria (ECB)

2,358 col/100 mL Primary contact (swimming in swim beach, public water or 

public access) recreation criterion from November to March for a geometric mean of at least five samples in 30-day period (Kansas Department of Health and Environment, 2005).

3,843 col/100 mL Primary contact (swimming in private water, no access) 

recreation criterion from November to March for a geometric mean of at least five samples in 30-day period (Kansas Department of Health and Environment, 2005).

2,358 col/100 mL Secondary contact (wading in public water or public access) 

recreation criterion at any time during the year for a single sample (Kansas Department of Health and Environment, 2005).

3,843 col/100 mL Secondary contact (wading in private water, no access) recreation criterion at any time during the year for a single sample 

(Kansas Department of Health and Environment, 2005).

Atrazine (Atr) Triazine herbicides, such as atrazine, are commonly applied to 

crops (corn and sorghum) to control the growth of weeds. Typically are applied to fields during the growing season, and high concentrations in surface water result from rainfall and runoff.

3 μg/L MCL for atrazine in finished drinking water as an annual 

average and Kansas Department of Health and Environment chronic aquatic life criteria for atrazine (U.S. Environmental Protection Agency, 2003a; Kansas Department of Health and Environment, 2005).

170 mg/L Acute-aquatic-life criterion (Kansas Department of Health and 

Environment, 2005).

1SDWRs are nonenforceable guidelines for drinking water recommended by the U.S. Environmental Protection Agency and the States for aesthetic effects, such as taste and odor (U.S. Environmental 

Protection Agency, 2002b).

2 MCLs are the maximum permissible levels of a contaminant in drinking water and is enforceable by the U.S. Environmental Protection Agency and the States (U.S. Environmental Protection Agency, 

2002b). The criteria level is assigned at a level where there is a known adverse effect on humans consuming water exceeding the criterion value.
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