U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008–5176

Prepared in cooperation with the Indiana Department of Environmental Management

Total Mercury and Methylmercury in Indiana Streams, 

August 2004–September 2006
Upper left—East Fork Whitewater River at Brooksville, Indiana, USGS 

site 03276000. (Photogaph by Martin R. Risch, USGS)

Lower right—Maumee River at New Haven, Indiana, USGS 

site 04183000. (Photogaph by Amanda L. Ulberg, USGS)
Total Mercury and Methylmercury in Indiana Streams, 

August 2004–September 2006

In cooperation with the Indiana Department of Environmental Management

Scientific Investigations Report 2008–5176

U.S. Department of the Interior

U.S. Geological Survey

By Amanda L. Ulberg and Martin R. Risch
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

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

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Suggested citation:

Ulberg, Amanda L., and Risch, Martin R., 2008, Total mercury and methylmercury in Indiana streams, August 

2004–September 2006: U.S. Geological Survey Scientific Investigations Report 2008–5176, 76 p.

ISBN 978-1-4113-2290-5
iii

Contents

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

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

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

Description of the Study Area ............................................................................................................2

Mercury in the Environment ...............................................................................................................2

Monitoring of Mercury in Indiana Streams......................................................................................4

Methods...........................................................................................................................................................5

Monitoring Station Selection..............................................................................................................5

Sample Collection and Processing..................................................................................................11

Sample Analysis..................................................................................................................................15

Additional Measurements.................................................................................................................17

Data Analysis.......................................................................................................................................18

Quality Assurance and Quality Control ....................................................................................................18

Total Mercury and Methylmercury in Indiana Streams ........................................................................19

Sample Characteristics .....................................................................................................................20

Total Mercury and Methylmercury Concentrations......................................................................21

Highest Concentrations ............................................................................................................23

Concentrations That Exceeded a Standard ..........................................................................24

Particulate Mercury ..................................................................................................................26

Concentrations in Relation to Sampling Locations and Upstream Drainage Areas................29

Seasonal Variations in Concentrations...........................................................................................29

Concentrations in Relation to Water-Quality Characteristics and Streamflow .......................33

Summary........................................................................................................................................................39

Acknowledgments.......................................................................................................................................40

References Cited..........................................................................................................................................40

Appendixes 1–7............................................................................................................................................43

1. Total mercury concentrations in quality-control field-blank samples 

from mercury monitoring in Indiana streams, August 2004–September 2006..........................44

2. Total mercury concentrations in environmental and field-duplicate samples 

from mercury monitoring in Indiana streams, August 2004–September 2006..........................46

3. Methylmercury concentrations in environmental and field-duplicate samples 

from mercury monitoring in Indiana streams, August 2004–September 2006..........................47

4. Matrix-spike and spike-duplicate sample quality-control data from mercury

monitoring in Indiana streams, August 2004–September 2006 ...................................................48

5. Total mercury and methylmercury concentrations in water samples 

from monitoring in Indiana streams, August 2004–September 2006, 

and streamflow conditions at the time of sample collection ......................................................50

6. Estimated particulate total mercury and particulate methylmercury 

concentrations and methylation efficiencies in water samples from monitoring 

in Indiana streams, August 2004–September 2006 .......................................................................59

7. Instantaneous streamflow and water-quality characteristics at monitoring

stations for mercury in Indiana streams, August 2004–September 2006 ..................................68
iv

Figures

1–2. Maps showing:

1. Locations of monitoring stations for mercury in Indiana streams,

 August 2004–September 2006...........................................................................................8

2. Locations of monitoring stations for mercury in Indiana streams, 

August 2004–September 2006, and upstream drainage areas and 

hydrologic systems..............................................................................................................9

3. Graphs showing daily mean streamflow and daily precipitation at 

six selected monitoring stations for mercury in Indiana streams, 

August 2004–August 2006..........................................................................................................12

4–8. Photographs showing:

4. Method used on a bridge to collect water samples for analysis 

of mercury in Indiana streams by use of a US DH-95 sampler 

suspended from a cable reel on a portable bridge crane ..........................................14

5. Method used while wading to collect water samples for 

analysis of mercury in Indiana streams by use of a 

US DH-81 sampler on a wading rod................................................................................14

6. Isokinetic sampler (US D-95) with a nozzle used to collect 

water samples for analysis of mercury in Indiana streams .......................................15

7. Class 100, laminar-flow, high-efficiency particulate-air filter 

work station and apparatus used to filter water samples for 

analysis of mercury in Indiana streams.........................................................................16

8. U.S. Geological Survey Mercury Research Laboratory facilities 

used for analysis of mercury in water samples from Indiana streams ....................17

9. Map showing locations of monitoring stations with unfiltered 

total mercury concentrations that equaled or exceeded the Indiana 

chronic aquatic criterion for mercury, August 2004–September 2006 .....................25

10–14. Graphs showing:

10. Estimated total particulate mercury and turbidity in water 

at the time of sample collection at 25 monitoring stations in Indiana, 

August 2004–September 2006..........................................................................................27

11. Estimated total particulate mercury and turbidity in water at the 

time of sample collection by streamflow statistical category for 

24 monitoring stations on Indiana streams, August 2004–September 2006.............28

12. Distributions of concentrations of unfiltered total mercury and unfiltered

methylmercury in water samples at 25 monitoring stations in Indiana,

 August 2004–September 2006.........................................................................................30

13. Distributions of concentrations of unfiltered total mercury and unfiltered

methylmercury in water samples during four seasons in Indiana, 

August 2004–September 2006..........................................................................................32

14. Unfiltered total mercury and methylation efficiency by streamflow 

statistical category, for 24 monitoring stations on Indiana streams, 

August 2004–September 2006..........................................................................................38
v

Tables

1. Summary of some previous studies of total mercury and 

methylmercury in streams of the United States ......................................................................4

2. Characteristics of monitoring stations for mercury in Indiana 

streams, August 2004–September 2006 ....................................................................................6

3. Land–use settings of monitoring stations for mercury in Indiana 

streams, August 2004–September 2006 ..................................................................................10

4. Constituents and water-quality characteristics reported in samples 

from Indiana streams, August 2004–September 2006 ..........................................................16

5. Water samples collected from streams in Indiana and analyzed for 

mercury, August –September 2006, grouped by hydrologic system, 

season, and streamflow ............................................................................................................20

6. Summary statistics for total mercury and methylmercury 

concentrations, estimated particulate mercury and methylmercury, 

and methylation efficiency in water samples from the monitoring 

network in Indiana, August 2004–September 2006. ..............................................................21

7. Ranges and medians of total mercury and methylmercury 

concentrations, estimated particulate mercury and methylmercury, 

and methylation efficiency in water samples from 25 monitoring stations 

in Indiana, August 2004–September 2006...............................................................................22

8. Monitoring stations with unfiltered total mercury concentrations that 

equaled or exceeded the Indiana chronic aquatic criterion for mercury, 

August 2004–September 2006...................................................................................................24

9. Mercury concentrations and instantaneous streamflow for samples 

from Indiana streams, August 2004–September 2006, grouped by 

drainage area upstream from monitoring station .................................................................31

10. Median concentrations of mercury in water samples and median 

streamflow and median water–quality characteristics at the time of sample 

collection during four seasons in Indiana, August 2004–September 2006 .......................33

11. Summary statistics for water–quality characteristics and 

streamflow in water samples from 25 monitoring stations in Indiana, 

August 2004–September 2006...................................................................................................33

12. Ranges and medians of water–quality characteristics and streamflow 

from 25 monitoring stations in Indiana, August 2004–September 2006 .............................34

13. Highest unfiltered total mercury concentrations in water samples 

from Indiana streams, August 2004–September 2006, and turbidity 

at the time of sample collection ...............................................................................................36

14. Median mercury concentrations and methylation efficiency in 

water samples from Indiana streams, August 2004–September 2006, 

by streamflow statistical category...........................................................................................37
vi

Conversion Factors

Multiply By To obtain

inch (in.) 25.4 millimeter (mm)

foot (ft) .3048 meter (m)

mile (mi) 1.609 kilometer (km)

acre 4,047 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

foot per second (ft/s) .3048 meter per second (m/s) 

cubic foot per second (ft3/s) .02832 cubic meter per second (m3/s)

milliliter (mL) .03382 ounce, fluid (fl.oz)

liter (L) 33.81 ounce, fluid (fl. oz)

gram (g) .03527 ounce, avoirdupois (oz)

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum 

of 1929 (NGVD29).

Altitude, as used in this report, refers to distance above the vertical datum.

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

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

or nanograms per liter (ng/L). 

Concentrations of a chemical in solid are given in micrograms per kilogram (μg/kg).

A kilogram is 1,000 grams.

A milligram is 0.001 gram and 1,000 milligrams equal 1 gram.

A microgram is 0.001 milligram and 1,000 micrograms equal 1 milligram.

A nanogram is 0.001 microgram and 1,000 nanograms equal 1 microgram.

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

(μS/cm at 25 °C).

Turbidity is given in nephelometric turbidity ratio units (ntru).
Total Mercury and Methylmercury in Indiana Streams, 

August 2004–September 2006

By Amanda L. Ulberg and Martin R. Risch

Abstract

Total mercury and methylmercury were determined by 

use of low (subnanogram per liter) level analytical methods in 

225 representative water samples collected following ultraclean protocols at 25 Indiana monitoring stations in a statewide network, on a seasonal schedule, August 2004–September 2006. The highest unfiltered total mercury concentrations 

were at six monitoring stations—five that are downstream 

from urban and industrial wastewater discharges and that have 

upstream drainage areas more than 1,960 square miles and one 

that is downstream from active and abandoned mine lands and 

that has an upstream drainage area of 602 square miles. 

Total mercury concentrations in unfiltered samples 

ranged from 0.24 to 26.9 nanograms per liter (ng/L), with a 

median of 2.35 ng/L. The highest concentrations of total mercury, those in the 90th percentile and above, were more than 

9.05 ng/L, and most were in samples collected during winter 

and spring 2006 during changing streamflow hydrograph 

conditions. Seasonal medians for unfiltered total mercury were 

highest during winter and spring. Instantaneous streamflow 

and turbidity at the time of sample collection also were highest 

in winter and spring and potentially indicate conditions for the 

most particulate mercury transport. 

Samples with the highest total mercury concentrations 

were from water that had the highest turbidity at the time of 

sample collection. Unfiltered total mercury concentrations 

were significantly lower in samples collected at five stations 

downstream from dams. Values for particulate total mercury and streamflow also were significantly lower at these 

five stations.

Total mercury concentrations equaled or exceeded 

the 2007 Indiana chronic aquatic criterion of 12 ng/L in 

5.8 percent of samples and at 10 monitoring stations. Most 

of the total mercury in these 13 samples was estimated to be 

particulate. Most of the samples with mercury concentrations 

that equaled or exceeded the 12 ng/L criterion were collected 

during winter and spring 2006 during changing streamflow 

hydrograph conditions and in streamflow that was high for 

2004–2006.

Methylmercury was detected in 83 percent of unfiltered samples; reported concentrations ranged from 0.04 to 

0.57 ng/L, with a median of 0.09 ng/L. The highest concentrations of methylmercury, those in the 90th percentile and above, 

were more than 0.25 ng/L, and most were in samples collected 

during spring and summer. Methylation efficiency in most 

samples was less than 5.8 percent, but was as much as 24.6 

percent. Seasonal medians for methylmercury were highest 

during spring and summer. Seasonal medians for water temperatures at the time of sample collection were highest during 

these seasons and potentially indicate conditions for the most 

formation of methylmercury. The low streamflow statistical 

category had the significantly highest methylation efficiency.

Introduction

A monitoring program for mercury in Indiana streams 

was operated by the U.S. Geological Survey (USGS) in 

cooperation with the Indiana Department of Environmental 

Management (IDEM). The data from the monitoring program 

support assessments of the efficacy of mercury regulations and 

provide information for policymakers and resource managers 

who make decisions about mercury that could affect aquatic 

ecosystems in Indiana. Mercury concentrations measured 

through this monitoring program required subnanogramper-liter level analytical techniques at a USGS laboratory 

designed for mercury research. In addition, specialized 

equipment and ultraclean protocols were used to obtain and 

process representative stream-water samples for the low-level 

mercury analysis.

Purpose and Scope

This report presents total mercury and methylmercury 

concentrations in 225 water samples collected from streams 

in Indiana at 25 stations in a statewide monitoring network, 

August 2004–September 2006. The report summarizes 

data from 88 quality-control samples and streamflow and 

water-quality characteristics at the time of sample collection. Methods of study are described. Mercury concentrations 

are compared with Indiana water-quality standards, selected 

water-quality characteristics, and streamflow. Mercury 
2 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

concentrations are displayed in maps, tables, and graphs, with 

regard to monitoring locations, upstream drainage areas, and 

seasons. Estimates of mercury loads and statistical evaluations 

of factors affecting mercury concentrations are outside the 

scope of this report.

Description of the Study Area

Indiana is 35,887 mi2 in size, 38th in geographic area 

in the Nation. The State population estimate in 2006 was 

6.3 million, 15th in the Nation; population density was 176 

individuals per mi2. Children represent one-fourth of the total 

Indiana population (Indiana Business Research Center, 2007)1. Indiana has 35,673 mi of rivers, 575 publicly owned lakes and 

reservoirs that total 106,205 acres, 813,000 acres of wetlands, 

and 59 mi of Lake Michigan shoreline (Indiana Department of 

Environmental Management, 2006). 

The climate of Indiana is continental, influenced mainly 

by eastward-moving cold polar and warm gulf-air masses. 

The low-pressure centers formed by the interaction of these 

air masses are the major sources of precipitation in Indiana. 

Spring and early summer are normally the wettest periods of 

the year, as storm systems tap moisture from the Gulf of Mexico and travel across Indiana. Early fall is generally the driest 

period. Seasonal precipitation patterns vary statewide, particularly in the summer when isolated thunderstorms are common 

and during the winter when lake-effect snows fall in northern 

Indiana. Mean annual temperature in Indiana is approximately 

52°F and ranges from 49.6°F in the north to more than 54.8°F 

in the south (Purdue Applied Meteorology Group, 2005). 

The statewide mean annual precipitation is 42 in. and 

ranges from 37 in. for northern Indiana to nearly 47 in. for 

southern Indiana. Snowfall (as liquid) accounts for 2 to 7 in. 

of the mean annual precipitation, and the greatest amounts 

of snow fall in northern Indiana (Morlock and others, 2004; 

Purdue Applied Meteorology Group, 2005). According to 

Clark (1980), approximately 68 percent of the mean annual 

precipitation in Indiana returns to the atmosphere through 

evapotranspiration, 24 percent enters streams and lakes 

through surface runoff, and 8 percent recharges ground water. 

Generally, runoff is greatest in areas with steep slopes and 

relatively impermeable soils, which are characteristic of much 

of the southern one-third of Indiana.

Mercury in the Environment

Mercury is a metallic element that occurs in the environment from natural and anthropogenic sources. It poses risks 

as an environmental contaminant, and it has been linked to 

1

 According to the Indiana Business Research Center (2007), children 

less than 4 years in age (0.43 million) plus children 5 to 17 years in age 

(1.15 million) total 1.6 million of the 6.3 million total Indiana population 

(25.4 percent).

adverse health effects in humans and wildlife. Naturally occurring mercury is found as mercuric sulfide, or cinnabar, in rock 

and soil. Mercury can be released into the environment during 

volcanic eruptions and forest fires. Anthropogenic sources 

of mercury include emissions to the atmosphere from fossil 

fuel combustion, waste incineration, and industrial processes. 

Aquatic ecosystems receive mercury from atmospheric deposition (National Research Council, 2000) and through wastewater discharge, including discharge from household, medical, 

and dental sources (U.S. Environmental Protection Agency, 

2008). The State of Indiana has designated mercury as a “bioaccumulative chemical of concern” (Indiana Administrative 

Code, 2007a). 

 Low concentrations of inorganic mercury in aquatic 

ecosystems can be converted to organic methylmercury by 

microorganisms. Methylmercury is highly absorbable and 

concentrations accumulate and magnify in food chains. 

Concentrations of methylmercury in water have been strongly 

correlated with bioaccumulation of mercury in fish (Brumbaugh and others, 2001). The greatest concentrations are 

present in fish and in fish-eating mammals and birds at the top 

of the food chain. Methylmercury is a potent neurotoxin and 

potential endocrine disruptor that can slow nervous-system 

and cognitive development in humans and wildlife. Methylmercury can interfere with reproduction in vertebrates (Klaper 

and others, 2006), and it has been linked to congenital birth 

defects, increased risk of heart attack, renal damage, and blood 

pressure dysfunction (National Research Council, 2000). 

The U.S. Environmental Protection Agency (2001a) 

freshwater criterion for mercury is based on a level for mercury in fish tissue of 0.3 micrograms per kilogram (μg/kg). 

The Indiana Water-Quality Standards list three criteria for 

mercury expressed as total mercury concentration. Statewide, 

the chronic aquatic criterion for mercury is 12 nanograms per 

liter (ng/L) to protect aquatic life from chronic toxic effects 

(Indiana Administrative Code, 2007a). The State of Indiana 

lists two criteria for water in the Great Lakes System, which 

includes “all the streams, rivers, lakes, and other waters of the 

state within the drainage basin of the Great Lakes (Lake Michigan and Lake Erie) within Indiana” (Indiana Administrative 

Code, 2007b). For water in the Great Lakes System, Indiana’s 

water-quality criterion for mercury, including methylmercury, 

is 1.8 ng/L, and it is intended to protect human health from 

possible noncancerous effects resulting from consumption 

of aquatic organisms (Indiana Administrative Code, 2007b). 

An additional water-quality criterion for mercury, including 

methylmercury, of 1.3 ng/L for water in Indiana in the Great 

Lakes System is intended to protect avian and mammalian 

wildlife populations from adverse effects that may result from 

consumption of aquatic organisms (Indiana Administrative 

Code, 2007b). 

Wastewater dischargers in Indiana are required to meet 

the applicable surface-water standards for mercury or obtain 

a permit variance. One justification for the availability of a 

permit variance for mercury is that ambient mercury concentrations in some streams are expected to exceed the standard. 
Introduction 3

In part, ambient mercury concentrations in Indiana streams 

are thought to be influenced by nonpoint-source contributions, 

primarily runoff and direct input from atmospheric deposition. 

Concentrations of mercury in precipitation in Indiana, 2001–

2003, were greater than the 12 ng/L Indiana chronic aquatic 

criterion in 47 percent of 517 samples; nearly all precipitation 

samples exceeded the most conservative Indiana water-quality 

criterion of 1.3 ng/L (Risch, 2007).

Mercury has been detected in nearly all fish-tissue 

samples collected in Indiana since 1983 (Stahl, 1997). Concentrations of mercury in some tissue samples have prompted 

State health officials to issue advisories warning about human 

consumption of fish (Indiana State Department of Health, 

2008). The Indiana annual fish consumption advisories are 

based on the U.S. Environmental Protection Agency Reference 

Dose2 and measured concentrations of mercury in fish-tissue 

samples collected throughout the state. These advisories recognize a greater risk to some members of the population. The 

advisories can be summarized generally with the following 

statements. If safety is unknown, women who are pregnant, 

breast-feeding, or planning pregnancy and children less than 

15 years of age may assume that one meal of Indiana sport fish 

per month is safe. Women and children in this group should 

not eat any large carp, flathead catfish, walleye, sauger, or 

striped bass. Adult men and women not in the previous group 

may assume that one meal of Indiana sport fish per week is 

safe; however, some Indiana rivers and streams have “do 

not eat” advisories for all fish (Indiana State Department of 

Health, 2008). 

As of 2006, fish-consumption advisories for mercury 

applied to fish caught in 3,113 mi or 9 percent of streams, 

40,628 acres or 38 percent of lakes, and all 59 mi of Great 

Lakes shoreline in Indiana (Indiana Department of Environmental Management, 2006). According to the IDEM, 524 

Indiana stream segments were classified as having impaired 

beneficial use because of fish-consumption advisories for 

mercury. Each year, some 833,000 resident anglers 16 years 

and older spend 15.5 million person-days and $469 million 

fishing. An estimated 286,000 more resident anglers were 

6 to 15 years old (U.S. Department of the Interior, 2003). 

Based on these numbers, fish-consumption advisories could 

affect approximately 1 of 6 Indiana residents.3

Particulate and filtered total mercury and methylmercury in water have been monitored in many ecosystems 

as explained by Mason and others (2005), and changes in 

2

 The U.S. Environmental Protection Agency Reference Dose is 0.1 μg 

mercury per kg of body weight per day of exposure for women of childbearing years, nursing mothers, and all children under age 15. The Reference 

Dose is 0.3 μg mercury per kg of body weight per day of exposure for women 

beyond their childbearing years and adult men (Indiana State Department of 

Health, 2006).

3

 The sum of 833,000 Indiana resident anglers over 16 years in age and 

an estimated 286,000 resident anglers 6 to 15 years in age is approximately 

1 million Indiana anglers out of 6.3 million Indiana residents (Indiana Business Research Center, 2007).

concentrations are expected to be an indicator of response 

to changes in atmospheric mercury deposition. It is noted, 

however, that interpreting the response of mercury concentrations in water to changes in atmospheric mercury input may 

be difficult. Mercury concentrations in water can be influenced 

by factors unrelated to mercury inputs, such as the variation 

in organic carbon and particulate matter. Some studies have 

shown a reasonable correlation between methylmercury in 

water and in fish that reflects changes at the base of the food 

chain, and one study includes a prediction that reductions 

in mercury emissions will rapidly decrease methylmercury 

concentrations in fish (Harris and others, 2007). In addition, 

recent studies in the northeastern United States (Evers, 2005) 

demonstrated that mercury exposure can be related to populationwide effects in fish and wildlife.

Four previous studies of total mercury and methylmercury in streams in the U.S. have involved different sizes of 

study areas—nationwide, multistate, and single state (table 1). 

A nationwide study from June through October 1998 analyzed 

mercury in stream-water samples from 106 locations in 21 

river basins (Krabbenhoft and others, 1999). Total mercury 

concentrations were a maximum of 1,107 ng/L, with a median 

of 2.3 ng/L; methylmercury concentrations were a maximum of 1.48 ng/L, with a median of 0.06 ng/L. Methylation 

efficiency (methylmercury concentration as a percentage of 

total mercury concentration), computed from their published 

data for water, was a maximum 47.2 percent, with a median of 

2.7 percent.

A multistate study in 1998–2001 analyzed mercury in 

stream-water samples from 25 locations in the 12,700-mi2

Delaware River Basin in Pennsylvania, New Jersey, and New 

York (Brightbill and others, 2004). Total mercury concentrations were a maximum of 22 ng/L, with a median of 1.3 ng/L; 

methylmercury concentrations were a maximum of 0.28 ng/L, 

with a median of 0.04 ng/L. Methylation efficiency computed 

from their published data was a maximum of 8.6 percent, with 

a median of 3.6 percent.

A statewide study in Wisconsin in 1993–94, analyzed 

mercury in nine monthly stream-water samples from locations 

on seven rivers (Babiarz and others, 1998). Total mercury 

concentrations were a maximum of 45.9 ng/L, with a median 

2.60 ng/L; methylmercury concentrations were a maximum of 

1.8 ng/L, with a median of 0.11 ng/L (concentrations less than 

the reporting limit were omitted). The authors reported that the 

maximum total mercury concentrations were associated with 

storm events. They also observed methylmercury detections 

at all locations only during summer. As reported by Babiarz 

and others, methylation efficiencies rarely exceeded 6 percent. 

Methylation efficiency computed from their published data 

was a maximum of 51.2 percent, with a median of 4.8 percent.

A previous study of total mercury in streams in the 

Midwest included two drainage basins in Indiana—the Indiana 

Harbor Canal and the St. Joseph River (table 1). This study 

in 1994 analyzed mercury in stream-water samples from 

11 tributaries of Lake Michigan in 3 states (Hurley and others, 1998). Total mercury concentrations were a maximum 
4 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

of 182 ng/L, with a mean of 9.02 ng/L. Total mercury concentrations in the Indiana Harbor Canal in Indiana were a 

maximum of 15.9 ng/L, with a median of 8.56 ng/L. Total 

mercury concentrations at the mouth of the St. Joseph River 

in Michigan were a maximum of 14.8 ng/L, with a median of 

5.34 ng/L. Particulate total mercury concentrations increased 

during spring snowmelt and other high streamflow conditions 

and coincided with high concentrations of suspended particulate matter. 

Monitoring of Mercury in Indiana Streams

Previous studies have analyzed mercury in stream-water 

samples from a small river basin in northwestern Indiana, 

from a large river basin in central-southern Indiana, and from 

multiple river basins statewide (table 1). Samples collected 

in Indiana prior to 1999 have been excluded from this discussion unless they were analyzed with methods capable of 

detecting mercury and methylmercury at subnanogram per 

liter concentrations, and collected with ultraclean protocols. 

For this discussion, particulate and filtered mercury concentrations are combined and are considered to be equivalent 

to unfiltered mercury concentrations summarized for other 

previous studies.

Mercury was analyzed in stream-water samples from 

as many as 15 locations on the Grand Calumet River/Indiana Harbor Canal in a small river basin in Lake County in 

northwestern Indiana in July 1999 (Stewart and others, 2001) 

and in August 2001 and May 2002 (Risch, 2005). Samples 

were collected during warm, dry-weather conditions and 

during cool, wet-weather conditions. Total mercury concentrations were a maximum of 19 ng/L, with a median of 4.6 ng/L; 

methylmercury concentrations were a maximum of 0.18 ng/L, 

with a median of 0.02 ng/L. Methylation efficiency was a 

maximum of 6.2 percent, with a median of 0.4 percent. Nearly 

all of the mercury transported in the Grand Calumet River was 

particulate mercury. 

Mercury was analyzed in stream-water samples at eight 

locations on the White River, in a large river basin in central and southern Indiana, in summer 2002, as part of the 

USGS National Water Quality Assessment program study of 

mercury in selected river basins nationwide (Brigham and 

others, 2003). Total mercury concentrations were a maximum 

of 7.61 ng/L, with a median of 2.11 ng/L; methylmercury 

concentrations were a maximum of 0.38 ng/L, with a median 

of 0.15 ng/L. Methylation efficiency computed from published data was a maximum of 15 percent, with a median of 

9.1 percent.

The IDEM initiated a statewide reconnaissance of 

concentrations of trace metals, including mercury, in Indiana 

streams during 2002–2004 (Steve Boswell, Indiana Department of Environmental Management, written commun., 2001). 

This reconnaissance utilized a network of 24 monitoring 

stations at USGS streamflow-gaging stations and involved collection of grab samples of water 3 to 4 times per year. These 

Table 1. Summary of some previous studies of total mercury and methylmercury in streams of the United States.

[ng/L, nanograms per liter; NR, not reported]

Scale of study

Number

of sample 

locations

Unfiltered total mercury 

concentration (ng/L)

Unfiltered methylmercury 

concentration (ng/L)

Methylation efficiency

(percent)

Maximum Median Maximum Median Maximum Median

Nationwide1 106 1,107 2.3 1.48 0.06 47.2 2.7

Multistate2 25 22 1.3 .28 .04 8.61 3.61

Statewide3 7 46 2.6 1.8 .11 51.2 4.8

Regional4 11 182 NR NR NR NR NR

Indiana small 

river basin5 15 19 4.6 .18 .02 6.2 .6

Indiana large river basin6 8 7.6 2.1 .38 .15 15.3 9.1

Indiana multiple river 

basins7

24 28 2.2 .66 .17 15 3.6

1

Krabbenhoft and others (1998); methylation efficiency computed from published data.

2

Brightbill and others (2004); methylation efficiency computed from published data.

3

Babiarz and others (1998); methylation efficiency computed from published data.

4

Hurley and others (1998).

5

Stewart and others (2001) and Risch (2005).

6

Brigham and others (2003).

7

Indiana Department of Environmental Management, Assessment Information Management System database, unpublished data (2005). 
Methods 5

samples were analyzed for total mercury and methylmercury 

(Indiana Department of Environmental Management Assessment Information Management System database, unpub. 

data, 2005). Unfiltered total mercury concentrations in 185 

samples were a maximum of 28.2 ng/L, with a median of 2.23 

ng/L; unfiltered methylmercury concentrations in 65 samples 

were a maximum of 0.66 ng/L, with a median of 0.17 ng/L. 

Methylation efficiency was a maximum of 64.8 percent, with 

a median of 3.6 percent. Filtered total mercury concentrations 

in 162 samples were a maximum of 5.86 ng/L, with a median 

of 0.56 ng/L (23 percent of the median unfiltered total mercury 

for these samples). Filtered methylmercury concentrations 

in 13 samples were a maximum of 0.68 ng/L, with a median 

concentration of 0.12 ng/L. Unfiltered total mercury in 4.9 

percent of the IDEM samples, or 9 of 185 samples, exceeded 

the 12 ng/L Indiana chronic aquatic criterion for mercury. 

Median unfiltered total mercury concentrations were higher 

during spring and winter (3.6 and 2.9 ng/L) than summer and 

fall (1.8 and 1.0 ng/L).

Data on ambient concentrations of mercury and methylmercury in Indiana streams have been used by the IDEM as a 

measure of progress toward achieving statewide water-quality 

standards. In addition, these mercury data can be used to interpret the relation of mercury in streams to mercury in fish and 

atmospheric mercury deposition in Indiana. During summer 

2004, the USGS, in cooperation with the IDEM, implemented 

a monitoring program that utilized 23 of the 24 stations in the 

IDEM network. Two new monitoring stations were included 

in the USGS network to replace a discontinued station, for 

a total of 25 stations. In 2004–2006, stream-water samples 

were collected once each season by use of stream-width and 

streamflow-integrating techniques. The results presented in 

this report are from 9 sets of 25 seasonal samples collected by 

the USGS during summer 2004 through summer 2006. 

Methods 

 Total mercury and methylmercury were determined for 

water samples collected from a statewide stream-monitoring 

network in Indiana. Samples were collected on a seasonal 

schedule, following ultraclean protocols, with equipment and 

techniques for obtaining representative samples, consistent 

with USGS practices nationwide. Samples were filtered and 

preserved under cleanroom conditions at the trace metals laboratory at the USGS Indianapolis office. Unfiltered 

and filtered water samples were analyzed for total mercury 

and methylmercury. Analyses were completed at the USGS 

Mercury Research Laboratory in Middleton, Wis. by use of 

low-level methods. Instantaneous streamflow was obtained 

from, or estimated with, data from the nearby USGS streamflow-gaging stations.

Monitoring Station Selection

The USGS network of monitoring stations for mercury 

in Indiana streams (table 2, fig. 1) consisted of 25 locations 

representing 78 percent of the land area in the State4. The locations are identified by a station number (1 through 25) in this 

report. The locations of 23 monitoring stations in the USGS 

network were selected by the IDEM in 2002 to represent 

major watersheds, reservoirs, sources of water supply, urban 

wastewater discharges, special habitats, and areas with active 

and abandoned mine lands (Steve Boswell, Indiana Department of Environmental Management, written commun., 2001). 

Stations 15 and 25 were added by the USGS in 2004. Most 

monitoring stations were at bridges where USGS streamflowgaging stations also are located. Five monitoring stations 

(stations 5, 12, 17, 18, and 25) were at bridges upstream or 

downstream from USGS streamflow-gaging stations. Station 6 was a tailwater pool below the Cagles Mill Lake dam, 

upstream from the USGS streamflow-gaging station.

The drainage areas upstream from the 25 monitoring stations (fig. 2) ranged from 59 mi2 for station 22 to 13,800 mi2 

for station 25. The 25 monitoring stations represent 6 major 

hydrologic systems—the Wabash River, White River, Illinois 

River, Ohio River, Lake Michigan, and Lake Erie Systems. 

White River is physically part of the Wabash River basin; 

however, it is treated as an independent hydrologic system in 

this report. The 25 monitoring stations also represent 11 IDEM 

water management basins—the Upper Wabash River, Middle 

Wabash River, Lower Wabash River, West Fork White River, 

East Fork White River, Maumee River, St. Joseph River, 

Kankakee River, Patoka River, Whitewater River, and Lake 

Michigan Basins (table 2). 

The monitoring stations represent different land-use 

settings primarily identified by the IDEM (table 3). Some stations represent more than one land-use setting. Five stations 

(6, 10, 17, 18, and 23) are within 2.7 mi downstream from a 

dam impounding a reservoir. Five stations are upstream from 

public water-supply intakes (1, 8, 12, 18, and 23). At least 

seven stations are downstream from urban and industrial 

wastewater discharges (5, 7, 8, 15, 19, 22, and 25); station 23 

is downstream from urbanized and developed land use. Two 

stations—stations 13 and 20—represent special habitats. Station 13 is on a stream designated by IDEM for “exceptional 

use” for reasons of exceptional natural beauty or character or 

support of unique assemblages of aquatic organisms (Indiana 

Administrative Code, 2007c). Station 20 is on a stream that 

supports three endangered species of mussels (Sparks and 

others, 1999). Stations 14 and 16 are in watersheds with active 

and abandoned mine lands. Sixteen stations are downstream 

from rural and agricultural land uses (1, 2, 3, 4, 6, 9, 10, 11, 

12, 13, 14, 17, 18, 20, 21, and 24).

4

 The total land area of Indiana is 35,887 mi2 and the sum of the unique 

drainage areas upstream from the 25 stations in the USGS stream-monitoring 

network, less any area outside the Indiana border, is 27,968 mi2.
6 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Table 2. Characteristics of monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [ddmmss, degrees minutes seconds; mi2, square mile; NGVD29, National Geodetic Vertical Datum of 1929; IDEM, Indiana Department of Environmental Management] Monitoring station number Station name Latitude (ddmmss) Longitude (ddmmss) National Water Information System station identifier USGS streamflow gaging station number Upstream drainage area (mi2

)

Altitude 

NGVD29

(feet)

IDEM water 

management 

basin

Major 

hydrologic 

system

Hydrologic 

unit

 code

 1 Fall Creek 

near Fortville, Ind.

395717 855203 03351500 03351500 173 787.4 West Fork White 

River

White 5120201

 2 Eel River 

near Logansport, Ind.

404655 861550 03328500 03328500 789 621.5 Upper Wabash River Wabash 5120104

 3 Tippecanoe River 

at Winamac, Ind.

410259 863557 03331753 03331753 941 674.2 Upper Wabash River Wabash 5120106

 4 Wildcat Creek 

near Lafayette, Ind.

402626 864945 03335000 03335000 794 527.7 Upper Wabash River Wabash 5120107

 5 Wabash River at U.S. Highway 40 at Terre Haute, Ind. 392801 872513 392801087251301 03341500 12,300 445.8 Middle Wabash River Wabash 5120111 6 Mill Creek at tailwater 

pool near Manhattan, Ind.

392911 865508 392911086550701 03359000 293 650.0 West Fork White 

River

White 5120203

 7 White River 

near Centerton, Ind.

392951 862402 03354000 03354000 2,440 595.4 West Fork White 

River

White 5120201

 8 White River 

near Nora, Ind.

395438 860620 03351000 03351000 1,220 710.9 West Fork White 

River

White 5120201

 9 Sugar Creek 

at New Palestine, Ind.

394251 855308 03361650 03361650 94 786.0 East Fork White 

River

White 5120204

10 East Fork Whitewater 

River at Brookville, Ind.

392602 850012 03276000 03276000 381 621.8 Whitewater River Ohio 5080003

11 Vernon Fork Muscatatuck 

River at Vernon, Ind.

385835 853711 03369500 03369500 198 585.0 East Fork White 

River

White 5120207

12 White River at State Road 

258 near Seymour, Ind.

385823 855546 385823085554501 03365500 2,340 560.0 East Fork White 

River

White 5120206

13 Blue River 

at Fredericksburg, Ind.

382602 861130 03302800 03302800 283 590.0 Ohio River Ohio 5140104

14 Patoka River 

at Winslow, Ind.

382249 871300 03376300 03376300 602 400.0 Patoka River Wabash 5120209
Methods 

7

Table 2. Characteristics of monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued[ddmmss, degrees minutes seconds; mi2, square mile; NGVD29, National Geodetic Vertical Datum of 1929; IDEM, Indiana Department of Environmental Management]

Monitoring 

station 

number

Station 

name

Latitude 

(ddmmss)

Longitude 

(ddmmss)

National Water 

Information 

System station 

identifier

USGS

streamflow

gaging

station number

Upstream 

drainage 

area 

(mi2)

Altitude 

NGVD29

(feet)

IDEM water 

management 

basin

Major 

hydrologic 

system

Hydrologic 

unit

 code

15 White River 

at Petersburg, Ind.

383039 871722 03374000 03374000 11,100 400.0 West Fork White 

River

White 5120202

16 Busseron Creek 

near Carlisle, Ind.

385827 872533 03342500 03342500 228 425.4 Lower Wabash 

River

Wabash 5120111

17 Mississinewa River 

at County Road 275 East near Peoria, Ind.

404330 855909 404330085590901 03327000 808 660.0 Upper Wabash River Wabash 5120103

18 Wabash River 

at County Road 200 West near Huntington, Ind.

405112 852923 405112085292301 03323500 766 700.0 Upper Wabash River Wabash 5120101

19 Maumee River 

at New Haven, Ind.

410506 850120 04183000 04183000 1,960 724.5 Maumee River Great Lakes 

(Lake Erie)

4100005

20 Fish Creek 

near Artic, Ind.

412754 844851 04177810 04177810 96 833.0 Maumee River Great Lakes 

(Lake Erie)

4100003

21 St. Joseph River 

at Elkhart, Ind.

414130 855830 04101000 04101000 3,380 700.0 St. Joseph River Great Lakes 

(Lake Michigan)

4050001

22 Trail Creek at Michigan City 

Harbor, Ind.

414322 865415 04095380 04095380 59 575.0 Lake Michigan Great Lakes 

(Lake Michigan)

4040001

23 Deep River at Lake George 

outlet at Hobart, Ind.

413210 871525 04093000 04093000 124 588.2 Lake Michigan Great Lakes 

(Lake Michigan)

4040001

24 Kankakee River at Shelby, 

Ind.

411058 872025 05518000 05518000 1,780 628.1 Kankakee River Illinois 7120001

25 Wabash River at Vigo Street 

at Vincennes, Ind.

384053 873207 384156087310701 03343000 13,800 394.4 Lower Wabash 

River

Wabash 5120111
ALLEN

UNION

OHIO

CRAWFORD

GIBSON

LAKE PORTER

LAPORTE

ST.JOSEPH

ELKHART

LAGRANGE STEUBEN

NOBLE DEKALB

KOSCIUSKO

MARSHALL

STARKE

WHITLEY

FULTON

PULASKI

JASPER

WHITE CASS WELLS

ADAMS

BENTON CARROLL

HOWARD

GRANT FORD

JAY

RANDOLPH TIPTON

CLINTON WARREN

PARKE PUTNAM

WAYNE

HENRY

MARION HANCOCK

RUSH

SHELBY

MORGAN JOHNSON

OWEN

CLAY

VIGO

FRANKLIN

DECATUR

MONR BROWN OE

RIPLEY

JENNINGS

LAWRENCE JACKSON

DAVIESS

GREENE

KNOX

JEFFERSON

ORANGE SCOTT

CLARK

FLOYD

PERRY

SPENCER

WARRICK

POSEY

PIKE

DUBOIS

SULLIVAN

MIAMI

NEWTON

WABASH

TIPPECANOE

MADISON

DELAWARE

HENDRICKS

VERMILLION

FAYETTE

BARTHOLOMEW

DEARBORN

SWITZERLAND

WASHINGTON

HARRISON

VANDER

BURGH

HUNTINGTON

FOUNTAIN

MONTGOMERY

BOONE HAMILTON

MARTIN

19

20

22 21

24

23

3

18

2

17

4

10

9

8 1

6 7

12 11

14

16

13

5

15

25

Base from U. S. Geological Survey digital data 1:100,000 1983

Universal Transverse Mercator projection zone 16

North American Dutum of 1983 (NAD83)

0 30 60

0 30 60 KILOMETERS

MILES

88°

38°

39°

40°

41°

87° 86° 85°

EXPLANATION

13 Monitoring station for

mercury in Indiana streams

and monitoring station number

8 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 1. Locations of monitoring stations for mercury in Indiana streams, August 2004–September 2006.
UUpstrea

EXPLANATION

Monitoring station and 

identification number

7

Hydrologic system:

 Wabash River

 White River

 Great Lakes

 Ohio River

 Illinois River

Drainage area upstream of

monitoring station

Base from U. S. Geological Survey digital data 1:100,000 1983

Universal Transverse Mercator projection zone 16

North American Datum of 1983 (NAD 83)

0 30 60

0 30 60 KILOMETERS

MILES

88°

38°

39°

40°

41°

87° 86° 85°

2

24

23

22

21 20

19

18

17

8 1

9

10

11

12

13

14

15

25

5

16

6 7

4

3

MICHIGAN

ILLINOIS OHIO

KENTUCKY

INDIANA

Methods 9

Figure 2. Locations of monitoring stations for mercury in Indiana streams, August 2004–September 2006, and 

upstream drainage areas and hydrologic systems.
10 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Table 3. Land–use settings of monitoring stations for mercury in Indiana streams, August 2004–September 2006.

Monitoring station 

number Station name Land–use setting or location of monitoring station

 1 Fall Creek near Fortville, Ind. Downstream from rural and agricultural land use; upstream from public 

water–supply intake. 

 2 Eel River near Logansport, Ind. Downstream from rural and agricultural land use.

 3 Tippecanoe River at Winamac, Ind. Downstream from rural and agricultural land use.

 4 Wildcat Creek near Lafayette, Ind. Downstream from rural and agricultural land use.

 5 Wabash River at U.S. Highway 40 at 

Terre Haute, Ind.

Downstream from urban and industrial wastewater discharges.

 6 Mill Creek at tailwater pool near 

Manhattan, Ind.

Downstream from reservoir; downstream from rural and agricultural land use.

 7 White River near Centerton, Ind. Downstream from urban and industrial wastewater discharges.

 8 White River near Nora, Ind. Downstream from urban wastewater discharges; upstream from public water–

supply intake.

 9 Sugar Creek at New Palestine, Ind. Downstream from rural and agricultural land use.

10 East Fork Whitewater River at 

Brookville, Ind.

Downstream from reservoir; downstream from rural and agricultural land use.

11 Vernon Fork Muscatatuck River at 

Vernon, Ind.

Downstream from rural and agricultural land use and forest.

12 White River at State Road 258 near 

Seymour, Ind.

Downstream from rural and agricultural land use; upstream from public 

water–supply intake. 

13 Blue River at Fredericksburg, Ind. Special habitat: “exceptional use” stream; downstream from rural and agricultural land use and forest.

14 Patoka River at Winslow, Ind. Downstream from active and abandoned mine lands; downstream from rural 

and agricultural land use and forest.

15 White River at Petersburg, Ind. Downstream from urban and industrial wastewater discharges.

16 Busseron Creek near Carlisle, Ind. Downstream from active and abandoned mine lands.

17 Mississinewa River at County Road 

275 East near Peoria, Ind.

Downstream from reservoir; downstream from rural and agricultural land use.

18 Wabash River at County Road 200 

West, near Huntington, Ind.

Downstream from reservoir; upstream from public water–supply intake; 

downstream from rural and agricultural land use.

19 Maumee River at New Haven, Ind. Downstream from urban and industrial wastewater discharges.

20 Fish Creek near Artic, Ind. Special habitat: endangered mussel species; downstream from rural and agricultural land use.

21 St. Joseph River at Elkhart, Ind. Downstream from rural and agricultural land use.

22 Trail Creek at Michigan City Harbor, Ind.Downstream from urban and industrial wastewater discharges.

23 Deep River at Lake George outlet at 

Hobart, Ind.

Downstream from reservoir; upstream from public water–supply; downstream 

from urbanized and developed land use.

24 Kankakee River at Shelby, Ind. Downstream from rural and agricultural land use.

25 Wabash River at Vigo Street at 

Vincennes, Ind.

Downstream from urban and industrial wastewater discharges.
Methods 11

Daily mean streamflow and daily mean precipitation for 

August 2004 through August 2006 are shown for six selected 

monitoring stations for mercury in Indiana streams (fig. 3). 

Streamflow data are from nearby USGS gaging stations and 

precipitation data are from nearby National Weather Service 

cooperative observer stations. These six monitoring stations 

represent a range of upstream drainage area sizes, land-use 

settings, and regions of Indiana. The ranges of mean daily 

streamflow vary with the upstream drainage area, and higher 

streamflow is shown for larger upstream drainage areas. Station 5, with an upstream drainage area larger than 10,000 mi2

, 

had maximum streamflow of approximately 120,000 ft3/s. 

Station 7, with an upstream drainage area larger than 1,000 

mi2, had maximum streamflow of approximately 50,000 ft3/s. 

Station 9, with an upstream drainage area smaller than 100 

mi2, had maximum streamflow of approximately 2,500 ft3/s. 

Station 6, unlike stations 5, 7, and 9 for example, is downstream from a dam that controls streamflow. The hydrograph 

for station 6 was computed with daily stream stage and has 

multiday time segments with unchanging streamflow. Regionally, station 19 is in northern Indiana, station 14 is in southern 

Indiana, and station 7 is in central Indiana. Bar graphs of 

precipitation near these stations show that daily maximums 

did not exceed 3.5 inches. Precipitation was recorded year 

round in all regions, but amounts were smallest in northern 

Indiana. In a few of the graphs, high precipitation corresponds 

with high streamflow, such as for station 14 in early 2006, and 

for stations 5, 7, and 9 in early 2005; more often, however, the 

increases in mean daily streamflow do not appear to be a direct 

response to nearby precipitation. 

Sample Collection and Processing

 Water samples were collected from a bridge, or while 

wading, or from a boat. (An inflatable, rubberized boat with a 

wooden floor and minimal amounts of metal was used primarily at station 6.) Samples were collected from a bridge by use 

of a US D-95 or US DH-95 sampler suspended from a cable 

reel on a portable bridge crane (fig. 4). Samples were collected 

while wading or from a boat by use of a US DH-81 sampler on 

a wading rod, with extensions as necessary (fig. 5). Materials for the samplers that contacted the water were of plastic 

construction or were plastic coated. Each sampler consisted of 

a 1-L Teflon bottle with a Teflon sampler cap and nozzle. The 

1-L bottle had been cleaned in a heated acid bath according to 

procedures for low-level mercury in the USGS National Field 

Manual (Wilde and Radtke, 1998) 5 and transported in new, 

doubled zip-seal plastic bags. 

Representative samples were collected according to 

USGS procedures in Wilde and Radtke (1998) that are 

intended to composite water collected across the full width 

and depth of the stream, thus accounting for differences in 

velocity and water chemistry. Prior to sample collection at a 

monitoring station, stream velocity at the swiftest point was 

measured by using a stopwatch to repeatedly time the passage of a float along a known distance. If stream velocity was 

greater than 1.5 ft/s, samples were obtained by use of a depthintegrating isokinetic sampler with a 1/4-in. Teflon nozzle 

(fig. 6). The nozzle accumulates water in the sample bottle 

at the stream velocity to assure a representative sample. If 

stream velocity was less than 1.5 ft/s, samples were collected 

as depth-integrated samples at multiple verticals, without 

a nozzle. In addition, prior to sample collection, the stream 

width was measured and divided into 10 to 15 equal-width 

increments so that samples could be collected in the center 

of each increment. Increments were marked on bridge rails 

or on a tagline stretched across the stream for wading or boat 

samples. In addition, the maximum depth of the stream was 

measured with a sounding weight so that a uniform transit rate 

for the sampler could be determined.

Water-sample collection and processing for total mercury 

and methylmercury analysis followed ultraclean protocols for 

low-level mercury in Wilde and Radtke (1998)6, which are 

comparable to the trace metals sample-collection methods in 

EPA Method 1669 (U.S. Environmental Protection Agency, 

1996) and the USGS Inorganic Protocol (Horowitz and others, 1994). Ultraclean protocols are designed to avoid the 

unintentional introduction of mercury or other contaminants 

into a sample. A minimum of two USGS personnel collected 

samples. To protect sample integrity, Tyvek lab coats and 

powder-free disposable nitrile gloves were used (fig. 5). Sampling procedures followed a “clean hands-dirty hands” outline. 

For example, one person (clean hands) handled sample bottles 

and inner bags of double-bagged supplies; the other person 

(dirty hands) handled sampling equipment and the outer bag 

of double-bagged supplies. All water for analysis of mercury 

was dispensed into Teflon bottles that had been cleaned in a 

heated acid bath according to procedures in Wilde and Radtke 

(1998)6 and transported in new, doubled zip-seal plastic bags. 

Each sample bottle contained 20 mL of 1-percent high-purity 

hydrochloric acid, which was emptied from the bottle before it 

was triple rinsed and filled with sample water.

The sampler was lowered and raised through the water 

column one or more times in the center of each equal-width 

increment to obtain a minimum 4 L total sample volume from 

5, 6 USGS National Field Manual for Collection of Water-Quality Data, 

chapter 5, section 5.6.4B, Low-Level Mercury, version 1.0, 10/2004,

http://water.usgs.gov/owq/FieldManual/chapter5/pdf/5.6.4.B_v1.0.pdf

6
0

10,000

20,000

30,000

40,000

50,000 USGS 03354000 

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

2004 2005 2006

DAILY PRECIPITATION, IN INCHES

0

40,000

80,000

120,000

STATION 5 

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

2004 2005 2006

DAILY PRECIPITATION, IN INCHES 0

5,000

10,000

15,000

20,000 USGS 04183000

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

2004 2005 2006

DAILY PRECIPITATION, IN INCHES

0

2,000

4,000

6,000

8,000

10,000 USGS 03376300

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

2004 2005 2006

DAILY PRECIPITATION, IN INCHES

0

1

2

3

NWS COOP 128723 

2004 2005 2006

2004 2005 2006 0

1

2

3

2004 2005 2006

NWS COOP 125407 

0

1

2

3

2004 2005 2006

NWS COOP 123037 

0

1

2

3

NWS COOP 128442

USGS 03341500 

STATION 5 

STATION 7 

STATION 7

STATION 19 

STATION 19 

STATION 14 

STATION 14 

12 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 3. Daily mean streamflow and daily precipitation at six selected monitoring stations for mercury in Indiana streams, 

August 2004–August 2006.
0

500

1,000

1,500

2,000

2,500 USGS 03361650

0

1,000

2,000

3,000

4,000

USGS 03359000 

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

2004 2005 2006

2004 2005 2006

EXPLANATION

Daily precipitation, August 2004 - August 2006

Daily mean streamflow, August 2004 - August 2006

USGS 03341500 - Wabash River at Terre Haute, Ind.

USGS 03354000 - White River near Centerton, Ind.

USGS 04183000 - Maumee River at New Haven, Ind.

USGS 03376300 - Patoka River at Winslow, Ind.

USGS 03361650 - Sugar Creek at New Palestine, Ind.

USGS 03359000 - Mill Creek near Manhattan, Ind.

USGS streamflow-gaging stations 

National Weather Service Cooperative Observer Stations

 128723 - Terre Haute, Ind. 

 125407 - Martinsville, Ind. 

 123037 - Fort Wayne, Ind. 

 128442 - Stendal, Ind. 

 123527 - Greenfield, Ind. 

 121647 - Cloverdale, Ind.

0

1

2

3

2004 2005 2006

2004 2005 2006

DAILY PRECIPITATION, IN INCHES

NWS COOP 123527

0

1

2

3

DAILY PRECIPITATION, IN INCHES

NWS COOP 121647

STATION 9

STATION 9 

STATION 6 

STATION 6 

Methods 13

Figure 3. Daily mean streamflow and daily precipitation at six selected monitoring stations for mercury in Indiana streams, 

August 2004–August 2006.—Continued
14 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 4. Method used on a bridge to 

collect water samples for analysis of 

mercury in Indiana streams by use of 

a US DH-95 sampler suspended from a 

cable reel on a portable bridge crane.

Figure 5. Method used while wading 

to collect water samples for analysis 

of mercury in Indiana streams by 

use of a US DH-81 sampler on a 

wading rod.
Methods 15

all increments sufficient for processing and analysis. A 14-L 

Teflon churn was used to thoroughly mix the composite of 

samples from all the increments. The churn has an internal 

perforated disc attached to a handle. Water was mixed by moving the disc up and down with the handle. The churn, sampler 

cap, and nozzle were cleaned prior to sampling with a sequential process of detergent solution scrub and deionized water 

rinse, 5-percent hydrochloric acid rinse, and ultrapure deionized water rinse; the deionized water had a specific conductance of less than 1.0 μS/cm. The clean churn was transported 

and operated inside new, doubled plastic bags.

While it was mixed in the churn, water for analysis of 

unfiltered mercury and unfiltered methylmercury was dispensed into clean 500-mL and 250-mL Teflon bottles. The 

composited sample water to be filtered was dispensed into the 

1-L Teflon bottle used to collect the sample. Unfiltered, unpreserved samples were stored in coolers, which were transported 

or shipped overnight to the USGS Indianapolis office. 

Within 24 hours of collection, samples were filtered 

and preserved in a Class 100, laminar-flow, high-efficiency 

particulate-air filter work station (fig. 7) in the trace metals 

laboratory at the USGS Indianapolis office. Filtered samples 

were pumped with a peristaltic pump from the 1-L bottle of 

unfiltered, mixed, composite sample. Samples were pumped 

through Teflon tubing, a short piece of c-flex pump-head tubing, and a 0.7-μm nominal pore-size quartz-fiber filter in a Teflon holder. The tubing and filter holder had been cleaned in a 

heated acid bath according to procedures in Wilde and Radtke 

(1998)6 and transported in new, doubled zip-seal plastic bags. 

Water for analysis of filtered mercury and filtered methylmercury was dispensed into clean 500-mL and 250-mL Teflon 

bottles. All samples for mercury analysis were preserved with 

50-percent high-purity hydrochloric acid at the rate of 5 mL 

of acid per 250 mL of sample. After filtering and preservation, and within 2 weeks of sample collection, samples were 

shipped by overnight freight to the USGS Mercury Research 

Laboratory for analysis.

Sample Analysis

Water samples were analyzed for mercury and waterquality constituents were determined by measurement in the 

field (table 4). Water samples were analyzed for mercury at 

the USGS Mercury Research Laboratory in Middleton, Wis. 

(table 4). Total mercury was analyzed by oxidation, purge and 

trap, and cold vapor atomic fluorescence spectrometry (Olson 

and DeWild, 1997), equivalent to EPA Method 1631 (U.S. 

Environmental Protection Agency, 1999). Methylmercury 

samples were prepared by distillation and analyzed by aqueous phase ethylation and gas chromatography separation with 

cold vapor atomic fluorescence detection (DeWild and others, 

2002), equivalent to EPA Method 1630 (U.S. Environmental 

Protection Agency, 1998). All total mercury and methylmercury determinations were made on multiple aliquots from each 

sample. Mercury concentrations in this report are the mean of 

the multiple-aliquot analyses.

The USGS Mercury Research Laboratory utilizes equipment to minimize potential mercury contamination including: 

high-efficiency particulate-air filters, mercury-free Class 100 

laminar flow hoods, gold-coated cloth filters at the intakes of 

the laminar flow hoods, a vinyl curtain at the main doorway, 

and tacky mats (fig. 8). Water purification systems provide 

ultrapure reagent grade water. The laboratory follows a written 

Figure 6. Isokinetic sampler 

(US D-95) with a nozzle used to collect 

water samples for analysis of mercury 

in Indiana streams. The nozzle was 

used to obtain a representative 

sample when the stream velocity was 

greater than 1.5 ft/s. A typical USGS 

streamflow-gaging station can be 

seen on the shoreline.
16 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Table 4. Constituents and water quality characteristics reported in samples from Indiana streams, August 2004–September 2006.

[ng/L nanograms per liter; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; oC, degree Celsius; ntru, nephelometric turbidity ratio unit]

Constituent Analysis Reporting 

limit

Unfiltered total mercury Oxidation, purge and trap, and cold vapor atomic fluorescence spectrometry 0.04 ng/L

Filtered total mercury Oxidation, purge and trap, and cold vapor atomic fluorescence spectrometry 0.04 ng/L

Unfiltered methylmercury Aqueous phase ethylation and gas chromatography separation with cold vapor atomic 

fluorescence

0.04 ng/L

Filtered methylmercury Aqueous phase ethylation and gas chromatography separation with cold vapor atomic 

fluorescence

0.04 ng/L

pH In–stream measurement with multiparameter instrument ±0.01 standard unit

Specific conductance In–stream measurement with multiparameter instrument ±1 μS/cm

Dissolved oxygen In–stream measurement with multiparameter instrument ±0.01 mg/L

Water temperature In–stream measurement with multiparameter instrument ±0.1 oC

Turbidity Field measurement of composite sample with portable turbidimeter ±0.1 ntru

Figure 7. Class 100, laminar-flow, highefficiency particulate-air filter work station 

and apparatus used to filter water samples 

for analysis of mercury in Indiana streams.
Methods 17

quality-assurance plan (U.S. Geological Survey, 2007) that 

details procedures for reagents, containers, instrument calibration and maintenance, quality control, record keeping, and 

quality-assurance reports.

Additional Measurements

A multiparameter instrument was used to measure pH, 

specific conductance, dissolved oxygen, and water temperature 

in the field. The meter was calibrated each day prior to its use, 

following procedures outlined in Wilde and Radtke (1998). 

Water-quality characteristics were measured at the center of 

the equal-width increments where the water samples were collected. Summary values for the stream at the time of sampling 

were recorded as the median pH, mean specific conductance, 

mean dissolved oxygen, and mean water temperature. A portable turbidimeter (Hach model 2100p) was used to measure 

turbidity in three aliquots drawn from the churn used to mix 

the composite water samples. A mean of the turbidity values in 

the three aliquots was reported as the summary turbidity value 

for each sample. The turbidimeter was checked with secondary standards each day prior to its use, and it was calibrated 

annually.

Instantaneous streamflow was determined with data 

obtained from the USGS streamflow-gaging station at or 

nearest each monitoring station, with the exception of station 

16. Hereafter in this report, “streamflow” refers to instantaneous streamflow. The hourly streamflow value closest to the 

time of sample collection was obtained for 19 monitoring 

stations. The hourly gage-height value closest to the time of 

sample collection (from USGS streamflow-gaging stations 

that provided only stage) was obtained for five monitoring 

stations. Streamflow was estimated for these five stations 

with the stream stage (gage height) and the most current 

stage-streamflow rating curve. Station 16 was discontinued 

as a USGS streamflow-gaging station after December 2, 2003 

(prior to the USGS sampling); streamflow measurements 

were therefore required at this station. For the first sample at 

station 16, during summer 2004, streamflow was computed 

as a product of stream velocity measured by use of a float and 

stopwatch, incremental depth, and stream width at the time of 

sampling. For the next eight samples at station 16, streamflow 

was measured with a handheld acoustic doppler velocimeter. 

Figure 8. U.S. Geological Survey Mercury Research Laboratory facilities used for analysis of mercury in water samples from 

Indiana streams.
18 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Streamflow measurements followed USGS methods in Rantz 

and others (1982).

Data Analysis

Bioaccumulation of mercury in fish is driven by many 

factors including total mercury load, methylation efficiency, 

fish size, and food chain dynamics in a given water body 

(Brumbaugh, 2001, 1999; Kidd and others, 1995). For this 

report, methylation efficiency was computed as the methylmercury concentration as a percentage of the total mercury 

concentration, following the method in Krabbenhoft and 

others (1999). Methylation efficiency was computed for 187 

samples in which both methylmercury and mercury concentrations were greater than the reporting limit.

Particulate mercury was not measured directly in the 

225 water samples collected during August 2004–September 

2006. Particulate mercury concentrations were estimated 

by subtracting the filtered concentration from the unfiltered 

concentration (appendix 6). The fraction of unfiltered mercury 

that was estimated to be particulate mercury was expressed as 

a percentage. Particulate mercury concentrations were computed for samples in which unfiltered mercury concentrations 

were greater than the reporting limit. For samples with filtered 

mercury concentrations less than the reporting limit, all of the 

mercury was estimated to be particulate.

Mercury concentration data in this report do not have a 

normal distribution; therefore nonparametric statistics are most 

appropriate for their analysis (Helsel and Hirsch, 1995). Nonparametric tests are completed on data ranks rather than the 

data values, thus minimizing the effects of outliers. Concentrations reported as less than the reporting limit of 0.04 ng/L 

were set equal to one-half of the reporting limit for ranking in 

the statistical tests and graphical presentations of data. 

A confidence level of 95 percent (significance level 

α=0.05) was used for all statistical tests. A p-value is reported 

for the statistical tests and compared to the significance level. 

If the p-value for a test is greater than 0.05, it indicates a 

statistically significant difference between two or more groups. 

The p-value is the "attained significance level" or the probability of incorrect reporting of a difference among groups or 

failure to report a statistically significant difference.

Three nonparametric tests are used in data analysis for 

this report. The Wilcoxon rank-sum test is a nonparametric test 

for determination of whether two groups of data come from 

the same population (Helsel and Hirsch, 1995). For comparisons involving three or more groups, the Kruskal-Wallis test 

was computed. The Kruskal-Wallis test is a nonparametric 

one-way analysis of variance used to accept or reject the null 

hypothesis that the groups of data have the same distributions. 

The alternate hypothesis is that at least one group differs in its 

distribution (Helsel and Hirsch, 1995). If the Kruskal-Wallis 

test rejects the null hypothesis, which indicates a difference 

among the groups, Tukey’s test was computed to determine 

which groups are statistically different. Tukey’s test is a 

multiple-stage test, computed on ranked data, which compares 

the medians of the distributions from each group (Helsel and 

Hirsch, 1995). 

Concentration data are summarized graphically in standard boxplots and a scatterplot. Boxplots provide visual summaries and comparisons of median, distribution, skewness, 

and presence of outliers among data sets (Helsel and Hirsch, 

1995). Upper and lower limits of the central boxes are defined 

by quartiles. 

Quality Assurance and Quality Control

A Quality Assurance Program Plan (QAPP) was prepared prior to the beginning of sample collection. The QAPP 

described the project approach to achieving quality assurance 

objectives of precision, accuracy, completeness, representativeness, and comparability. In addition, the QAPP outlined 

procedures for analytical calibration, quality-control checks, 

performance audits, and data validation. 

Field quality-control samples included field-blank and 

field-duplicate samples. For each set of 25 stream-water samples, 6 field-blank samples (4 equipment blanks and 2 source 

solution/bottle blanks) were prepared to evaluate cleaning of 

the sampling equipment. Blank water for mercury analysis 

was provided by the USGS Mercury Research Laboratory. 

Equipment-blank samples were collected by pouring blank 

water into the 1-L sample bottle, then through the sampler cap 

with nozzle into the churn; the sample was then mixed and 

dispensed into a 1-L bottle. In the Class 100, laminar-flow, 

high-efficiency particulate-air filter work station in the trace 

metals laboratory at the USGS Indianapolis office, the sample 

was pumped through the Teflon tubing, pump-head tubing, 

and a filter into a sample bottle. Source-solution/bottle-blank 

samples were collected by pouring blank water into a sample 

bottle. Field-blank samples were preserved in a manner identical to the stream-water samples. Field-blank samples were filtered and preserved in a manner identical to the stream-water 

samples. Field-blank samples were analyzed for filtered total 

mercury. Source-solution/bottle-blank samples were analyzed 

for unfiltered total mercury.

For each set of 25 stream-water samples, field-duplicate 

samples were collected at 3 or 4 different monitoring stations. Split-duplicate samples were prepared by sequentially 

filling a second set of sample bottles from the same churn. 

Concurrent-duplicate samples were collected simultaneously 

in two churns. Duplicate samples were filtered, preserved, and 

analyzed in a manner identical to the stream-water samples. 

Field-duplicate samples were analyzed for unfiltered and filtered total mercury and methylmercury. A total of 35 duplicate 

samples were collected, consisting of 19 split- and 16 concurrent-duplicates, for the 225 stream-water samples.
Total Mercury and Methylmercury in Indiana Streams 19

Laboratory quality-control samples included 71 matrixspike and spike-duplicate samples that were analyzed for unfiltered and filtered total mercury and unfiltered methylmercury. 

For a matrix-spike sample, a known concentration of mercury 

or methylmercury was added to a sample of stream water. The 

purpose of the matrix-spike samples was to quantify interference with determination of a mercury concentration due to the 

sampling matrix. Matrix-spike duplicate samples were used to 

evaluate the precision of the matrix-spike analyses. 

The following discussion summarizes the data from 

89 field quality-control samples and 71 laboratory quality-control samples associated with mercury analyses for this study. 

Quality-control data for the mercury concentrations from 

this study indicated there were few, if any, biases caused by 

artifacts from sampling and processing or by interference from 

the sampling matrix and that precision of the reported concentrations was not substantially affected by natural variability or 

variability from sampling and processing.

The 54 field-blank samples (appendix 1) consisted of 

18 bottle-blank samples to evaluate the blank water, sample 

bottles, and acid preservatives and 36 equipment-blank 

samples to evaluate the sampling and processing equipment. 

These field-blank data were evaluated with procedures for 

EPA Method 1631 (U.S. Environmental Protection Agency, 

2001b). Unfiltered total mercury concentrations greater than or 

equal to the 0.04 ng/L reporting limit were 0.04 and 0.06 ng/L 

in two source-solution/bottle-blank samples from two different sets of seasonal samples. Filtered total mercury was 

not detected in the equipment blanks associated with these 

samples and the average field-blank mercury concentration 

for each set of samples was less than the 0.04 ng/L reporting limit. Filtered total mercury concentrations greater than 

the 0.04 ng/L reporting limit were 0.05, 0.05, and 0.09 ng/L 

for three equipment-blank samples from two different sets of 

seasonal samples. Unfiltered total mercury was not detected 

in the source-solution/bottle-blank samples associated with 

these equipment-blank samples. The mean equipment-blank 

mercury concentration for these two sets of samples was less 

than or equal to one-fifth the filtered total mercury concentration in the associated environmental samples. On the basis of 

the field-blank evaluations, it was determined that no substantial mercury artifacts were introduced during sampling 

and processing of the samples that would bias the accuracy of 

reported concentrations.

Field-duplicate samples were a measure of the natural 

variability of mercury concentrations in the stream water and 

the variability associated with sample collection and processing, rather than a measure of analytical precision. Analytical 

precision in the determination of mercury concentrations was 

quality assured by the laboratory, through analysis of duplicate 

or triplicate aliquots of water from the same sample bottle 

until a control limit for a percentage difference of less than 

10 percent was attained. Each of the 35 field-duplicate samples 

was paired with the water sample (called “environmental 

sample” in this discussion) collected at the same station and 

date. Total mercury concentrations in the field-duplicate 

samples were compared with the mercury concentrations in 

the environmental samples by computing the relative percent 

difference7 (RPD) (appendix 2). Relative percent difference of 

methylmercury concentrations in the field-duplicate and environmental sample pairs were also computed (appendix 3). The 

median RPD’s were 8.2 and 9.8 for unfiltered and filtered total 

mercury. The median RPD’s of 13.3 and 15.4 for unfiltered 

and filtered methylmercury were higher than those for total 

mercury, although the median numerical differences between 

methylmercury concentrations of 0.01 ng/L were smaller compared with numerical differences of 0.22 ng/L and 0.06 ng/L 

for unfiltered and filtered methylmercury. These field-duplicate 

data indicate that most of the mercury concentrations in this 

report were not substantially affected by natural variability or 

variability from sampling and processing. 

The laboratory quality-control data (appendix 4) for 

60 matrix-spike and 11 spike duplicates for samples collected 

in Indiana had median percent recovery8 of 98 for unfiltered 

total mercury, 98 for filtered total mercury, and 99 for unfiltered methylmercury. No matrix-spike samples were performed for filtered methylmercury. These data indicate that the 

mercury concentrations were not biased by interference from 

the sample matrix. The laboratory quality-control data for 11 

matrix-spike-duplicate samples had a median RPD of 7.0 percent. These data indicate good agreement of the matrix-spike 

concentrations.

Total Mercury and Methylmercury in 

Indiana Streams

Concentrations of unfiltered and filtered total mercury 

and methylmercury (appendix 5) were analyzed and reported 

for 225 water samples collected from Indiana streams, August 

2004–September 2006. These samples represent the major 

hydrologic systems in Indiana, multiple seasons, and a range 

of streamflow conditions statewide. This section describes 

total mercury and methylmercury in the samples with regard 

to the highest concentrations, concentrations exceeding an 

Indiana Water Quality Standard, and estimated particulate 

mercury (appendix 6). Mercury data are discussed with regard 

to the locations, upstream drainage areas, and seasonal observation. Streamflow and water-quality characteristics (appendix 

7) at the time of sampling are summarized and compared to 

mercury concentrations.

7

 Relative percent difference is the nonnegative difference of the duplicate 

and environmental sample concentrations divided by the average of the concentrations, expressed as a percentage.

8

 Percent recovery was computed as the mercury concentration in the 

matrix-spike sample divided by the sum of the mercury concentration in the 

sample and the mercury concentration in the spike solution, expressed as 

a percentage.
20 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Sample Characteristics

The monitoring network was designed to provide data 

from the major hydrologic systems in Indiana (table 5). Of the 

225 samples, 36 percent were from the Wabash River System; 

32 percent from the White River System; 20 percent from the 

Great Lakes Systems, combining Lake Michigan and Lake 

Erie; 8 percent from the Ohio River System; and 4 percent 

from the Illinois River System. 

The schedule for sample collection was intended to 

include the variety of weather and streamflow conditions of 

the four seasons9 in Indiana. Two sets of water samples were 

collected at the 25 monitoring stations during winter (2005 

and 2006), spring (2005 and 2006), and fall (2004 and 2005); 

three sets of samples were collected during summer (2004, 

2005, and 2006). Streamflow hydrograph conditions at the 

time of sample collection were classified by an examination of 

several days of data from the nearby USGS streamflow-gaging 

station. The classifications (appendix 5) were stable (normal, 

low, high) and changing (peak, rising, falling). Slightly more 

than one-half of the samples, or 117 of 225, were collected 

during stable hydrograph conditions (table 5), including 3 

9

 Temperate seasons for the northern hemisphere are used in this report, and 

the changes are at dates of solstices and equinoxes: winter is from December 

22 to March 19; spring is from March 20 to June 21; summer is from June 22 

to September 22; and fall is from September 23 to December 21.

from a high stage. The 99 samples collected during changing 

hydrograph conditions included 2 at peak stage. Streamflow 

hydrograph conditions were not determined for the nine 

samples collected at station 16, because the streamflow-gaging 

station had been discontinued.

 Streamflow statistical category, for purposes of this 

report, was based on the daily mean streamflow record from 

the USGS streamflow-gaging station near each monitoring 

station, for water years 2004–2006 (October 1, 2003, through 

September 30, 2006). For five stations, the gage height record 

was used instead of streamflow. Statistical categories were 

based on the rank ordered streamflow (or gage-height) data for 

a monitoring station, and are defined as low (less than or equal 

to the 10th percentile), medium (greater than the 10th percentile to equal to the median), high (greater than the median to 

equal to the 90th percentile), and event (greater than the 90th 

percentile). Instantaneous streamflow at the time of sample 

collection was placed in one of these four statistical categories (appendix 5). Samples collected at Station 16 were not 

assigned a streamflow statistical category because data were 

not available.

Table 5. Water samples collected from streams in Indiana and analyzed for mercury, August –September 2006, 

grouped by hydrologic system, season, and streamflow.

Hydrologic system Season Streamflow 1

Name

Number

of 

samples

Name

Number

of 

samples

Hydrograph 

condition2

Number

of 

samples

Statistical

 category3

Number

of 

samples

Wabash River 81 Spring 50 Stable normal 39 Low flow 43

White River 72 Summer 73 Stable low 75 Medium flow 89

Ohio River 18 Fall 52 Stable high 3 High flow 58

Great Lakes 45 Winter 50 Peak stage 2 Event flow 26

Illinois River 9 Rising stage 31 Not determined 9

Falling stage 66

Not determined 9

1

 Streamflow was not classified for samples collected at station 16, due to discontinuation of USGS streamflow–gaging station.

2 Streamflow hydrograph condition classified from several days of streamflow data around the time of sample collection.

3

 Streamflow statistical category (October 1, 2003, through September 30, 2006): low (less than or equal to the 10th percentile), medium (greater than the 10th percentile to equal to the median), high (greater than the median to equal to the 90th 

percentile), and event (greater than the 90th percentile). 
Total Mercury and Methylmercury in Indiana Streams 21

Overall variability in the values of the water-quality 

characteristics (water temperature, specific conductance, and 

dissolved oxygen) at each sampling interval at a station were 

used to classify the stream conditions at the time of sample 

collection as well mixed or poorly mixed. Differences of less 

than 1 oC for water temperature, 5 μS/cm for specific conductance, and 3 mg/L for dissolved oxygen were used to classify 

stream conditions as well mixed. If differences were greater 

than these values, stream conditions were classified as poorly 

mixed. Stream conditions for 94 samples (42 percent) were 

classified as well mixed and 130 samples (58 percent) were 

classified as poorly mixed. Stream conditions for one sample 

were not classified because water-quality characteristics were 

not measured. Poorly-mixed streams were most susceptible to 

bias in the mercury concentration. This bias was minimized by 

the use of depth-integrating isokinetic, equal-width increment, 

and depth-integrating, multiple-vertical sampling techniques.

Total Mercury and 

Methylmercury Concentrations

In the following discussions, total and methylmercury 

concentrations are summarized, along with estimated particulate total mercury and methylmercury and methylation 

efficiency (table 6 shows all monitoring stations, table 7 shows 

each monitoring station). The highest concentrations and 

concentrations equal to or exceeding an Indiana Water Quality Standard are described with respect to location and time. 

Concentrations of total mercury and methylmercury, along 

with estimated particulate mercury, are compared according 

to upstream drainage areas, land uses, seasons, water-quality 

characteristics, and streamflow.

The 2.35 ng/L median unfiltered total mercury in 

225 samples, August 2004–September 2006 (table 6), was 

similar to median unfiltered total mercury in 187 samples 

collected at 23 of these stations by the IDEM, 2002–2004 

(2.23 ng/L). The range of concentrations (table 6) also was 

similar between August 2004–September 2006 (0.24 to 

26.9 ng/L) and 2002–2004 (0.19 to 28.1 ng/L). Median unfiltered total mercury between August 2004–September 2006 

(2.35 ng/L, table 6) was similar to the median of 2.3 ng/L for 

the Krabbenhoft and others (1999) nationwide study in 1998 

and slightly less than the median of 2.6 ng/L from the Babiarz 

and others (1998) statewide study in Wisconsin, 1993–1994. 

Median unfiltered methylmercury in August 2004–September 

2006 (0.9 ng/L, table 6) was about half the median unfiltered 

methylmercury in 65 samples collected by the IDEM, 2002–

2004 (0.17 ng/L). Median unfiltered methylmercury between 

August 2004–September 2006 was slightly higher than the 

median for the nationwide study in 1998 (0.06 ng/L) and 

slightly less than the median from the statewide study in Wisconsin, 1993–1994 (0.11 ng/L). Median methylation efficiency 

(table 6) was similar between August 2004–September 2006 

(3.7 percent, n=187) and 2002–2004 (3.6 percent, n=65) and 

was approximately nine times higher than the Risch (2005) 

Grand Calumet River/Indiana Harbor Canal study in Indiana 

in 2001–2002 (0.4 percent, n=18).

Table 6. Summary statistics for total mercury and methylmercury concentrations, estimated particulate mercury and methylmercury, 

and methylation efficiency in water samples from the monitoring network in Indiana, August 2004–September 2006.

[ng/L, nanograms per liter; <, less than; R.L., reporting limit of 0.04 ng/L]

Summary

 statistic

Unfiltered 

total 

mercury 

(ng/L)

Filtered 

total 

mercury 

(ng/L)

Unfiltered 

methyl–

mercury 

(ng/L)

Filtered 

methyl–

mercury 

(ng/L)

Particulate 

total 

mercury 

(ng/L)

Particulate 

methyl–

mercury 

(ng/L)

Methylation 

efficiency 

(percent)

Maximum 26.9 6.14 0.57 0.42 21.7 0.37 24.6

90th percentile 9.05 2.35 .25 .09 7 .21 10.3

75th percentile 4.60 1.21 .15 .06 3.43 .14 6.2

50th percentile (median) 2.35 .63 .09 .04 1.43 .07 3.7

25th percentile 1.31 .40 .05 <.04 .69 .03 2.2

Minimum .24 .06 <.04 <.04 .03 0 .4

Number of reported concentrations 225 225 187 116 225 116 187

Number of concentrations < R.L. 0 0 38 109 0 109 38

Total number of samples 225 225 225 225 225 225 225
22 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Table 7. Ranges and medians of total mercury and methylmercury concentrations, estimated particulate mercury and methylmercury, and methylation efficiency in water samples from 25 monitoring stations in Indiana, August 2004–September 2006.—Continued [ng/L, nanograms per liter; <, less than] Monitoring station number Unfiltered total mercury (ng/L) Filtered total mercury (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury (ng/L) Particulate total mercury (ng/L) Particulate methylmercury (ng/L) Methylation efficiency (percent) Range Median Range Median Range Median Range Median Range Median Range Median Range Median 1 0.39–21.2 1.28 0.22–4.17 0.43 <0.04–0.29 0.07 <0.04–0.06 <0.04 0.14–17.0 1.05 0.04–0.24 0.07 1.4 – 11.6 4.7 2 0.28–14.7 0.88 0.18–3.99 0.54 <0.04–0.27 0.06 <0.04–0.11 0.06 0.10–10.7 0.39 0–0.18 0.06 1.8 – 17.9 5.4 3 0.59–7.42 1.21 0.23–1.35 0.42 <0.04–0.19 0.06 <0.04–0.08 <0.04 0.27–6.19 0.72 0.05–0.14 0.09 1.8 – 7.2 4.6 4 0.34–8.33 1.39 0.26–1.11 0.48 <0.04–0.33 0.08 <0.04–0.13 <0.04 0.08–7.22 0.53 0.04–0.2 0.10 1.9 – 14.7 4.5 5 2.14–11.6 4.32 0.30–1.86 0.78 0.06–0.42 0.12 <0.04–0.05 <0.04 1.77–10.7 2.66 0.06–0.37 0.12 1.3 – 17.6 2.5 6 1.17–3.26 1.67 0.31–2.45 0.90 <0.04–0.57 0.12 <0.04–0.42 <0.04 0.15–1.25 0.85 0.06–0.26 0.14 3.1 – 24.6 12.5 7 2.90–17.8 6.34 0.54–1.53 0.80 0.07–0.29 0.12 <0.04–0.12 0.07 2.05–16.3 5.42 0–0.22 0.08 1.1 – 4.4 2.4 8 0.88–11.3 2.55 0.06–2.35 0.53 <0.04–0.26 0.09 <0.04–0.07 0.06 0.82–9.86 1.99 0.01–0.21 0.05 0.8 – 10.2 4.5 9 0.43–4.76 1.10 0.18–1.95 0.41 <0.04–0.12 0.04 <0.04–0.06 <0.04 0.25–2.81 0.45 0–0.08 0.04 2.5 – 9.3 7.1 10 0.24–1.85 0.54 0.17–1.21 0.40 <0.04–0.04 <0.04 <0.04–<0.04 <0.04 0.04–0.64 0.14 0.04–0.04 0.04 15.4–15.4 15.4 11 1.08–16.2 2.32 0.90–6.14 1.11 <0.04–0.20 0.08 <0.04–0.13 0.07 0.18–10.1 1.11 0–0.14 0.04 1.2 – 6.0 3.6 12 0.73–20.1 1.67 0.16–4.45 0.35 0.05–0.44 0.10 <0.04–0.08 0.04 0.5–15.7 1.3 0.05–0.36 0.06 1.2 – 9.8 4.4 13 0.83–2.96 1.98 0.43–1.90 0.67 <0.04–0.20 0.08 <0.04–0.13 <0.04 0.4–1.74 1.06 0–0.1 0.07 1.9 – 10.8 4.0

14 1.78– 16.0 3.97 0.30–4.40 0.95 0.05–0.32 0.07 <0.04–0.14 <0.04 1.26–11.7 2.75 0–0.18 0.07 0.4 – 4.8 2.515 3.42– 12.0 5.63 0.46–2.58 0.80 0.06–0.41 0.20 <0.04–0.10 <0.04 2.8–9.42 4.66 0.06–0.36 0.13 1.6 – 9.9 2.716 1.37–6.24 2.49 0.10–2.44 0.49 0.05–0.18 0.12 <0.04–0.13 0.05 0.03–4.05 2.07 0–0.13 0.07 1.9 – 6.5 4.517 1.12–3.39 2.31 0.32–2.16 0.99 0.05–0.18 0.06 <0.04–0.10 <0.04 0.44–1.99 1.09 0.01–0.16 0.06 1.5 – 16.1 2.918 1.24–15.0 2.67 0.35–5.85 1.68 0.04–0.40 0.12 <0.04–0.17 <0.04 0.89–9.15 1.91 0.04–0.23 0.08 0.7 – 15.4 2.4

19 3.45–26.9 9.28 0.46–5.97 1.00 0.07–0.43 0.23 <0.04–0.09 0.06 2.71–21.7 7.89 0.01–0.36 0.17 0.7 – 7.0 2.220 0.76–8.66 2.20 0.43–4.79 0.77 0.06–0.21 0.09 <0.04–0.10 0.06 0.25–6.33 1.35 0.01–0.21 0.06 1.0 – 10.3 7.9
Total Mercury and Methylmercury in Indiana Streams 23

Table 7. Ranges and medians of total mercury and methylmercury concentrations, estimated particulate mercury and methylmercury, and methylation efficiency in water samples from 25 monitoring stations in Indiana, August 2004–September 2006.—Continued[ng/L, nanograms per liter; <, less than]

Monitoring 

station 

number

Unfiltered 

total mercury 

(ng/L)

Filtered 

total mercury 

(ng/L)

Unfiltered 

methylmercury 

(ng/L)

Filtered 

methylmercury 

(ng/L)

Particulate 

total mercury 

(ng/L)

Particulate 

methylmercury 

(ng/L)

Methylation 

efficiency

(percent)

Range Median Range Median Range Median Range Median Range Median Range Median Range Median

21 0.39–9.05 1.77 0.25–2.28 0.48 <0.04–0.12 0.08 <0.04–0.12 0.05 0.14–6.77 1.15 0–0.1 0.02 1.1 – 12.5 4.522 0.55–7.15 1.42 0.17–3.31 0.40 <0.04–0.39 0.08 <0.04–0.23 0.05 0.38–3.84 0.68 0.01–0.16 0.03 1.3 – 6.3 5.323 1.37–6.89 1.85 0.55–3.17 0.80 <0.04–0.15 0.05 <0.04–0.11 <0.04 0.57–3.72 1.03 0–0.12 0.05 0.7 – 6.3 3.624 0.75–12.2 3.23 0.16–3.49 0.46 <0.04–0.13 0.07 <0.04–0.06 0.04 0.4–8.71 2.71 0–0.07 0.07 0.8 – 4.2 1.925 1.95–9.73 4.11 0.16–2.00 0.53 <0.04–0.42 0.16 <0.04–0.08 <0.04 1.79–8.04 3.19 0.08–0.34 0.15 1.6 – 16.5 2.3

Highest Concentrations 

Total mercury concentrations were greater than the 

0.04 ng/L reporting limit in all 225 unfiltered and filtered 

samples (appendix 5). Unfiltered total mercury ranged from 

0.24 to 26.9 ng/L, and filtered total mercury ranged from 0.06 

to 6.14 ng/L (table 6). Median unfiltered total mercury was 

2.35 ng/L and median filtered total mercury was 0.63 ng/L. 

The highest concentrations of unfiltered total mercury (in the 

90th percentile)10 ranged from 9.05 to 26.9 ng/L, and 13 of 

these 23 samples were collected during winter and spring, 

including 8 in March 2006 and 4 in May 2006. The highest 

concentrations of unfiltered total mercury were detected in 

10 samples from the White River System, 6 samples from 

the Wabash River System, 6 samples from the Great Lakes 

System, and 1 sample from the Illinois River System. Station 

19 (Maumee River at New Haven) was the location with the 

most (5 of 23) unfiltered total mercury concentrations in the 

90th percentile, three of these during changing streamflow 

hydrograph conditions. The majority of the highest unfiltered 

total mercury concentrations, 21 of 23, were collected during 

high or event streamflow.

Methylmercury concentrations were greater than the 

0.04 ng/L reporting limit in 83 percent (187 of 225) of unfil-

tered samples and 52 percent (116 of 225) of filtered samples. 

Concentrations less than the 0.04 ng/L reporting limit were 

included in the calculation of medians and summary statistics 

in this report. Unfiltered methylmercury concentrations ranged 

from <0.04 to 0.57 ng/L, and filtered methylmercury con-

centrations ranged from <0.04 to 0.42 ng/L (table 6). Median 

unfiltered methylmercury (including 38 censored values 

<0.04 ng/L) was 0.09 ng/L, and median filtered methylmer-

cury (including 109 censored values <0.04 ng/L) was 0.04 

ng/L. The highest concentrations of unfiltered methylmercury 

(in the 90th percentile) ranged from 0.25 to 0.57 ng/L, and 19 

of these 23 concentrations were measured during the spring 

and summer seasons. The highest unfiltered methylmercury 

concentrations were detected in 11 samples from the White 

River System, 8 samples from the Wabash River System, and 

4 samples from the Great Lakes System. Locations with the 

most unfiltered methylmercury concentrations in the 90th 

percentile were station 19 (Maumee River at New Haven) 

and station 15 (White River at Petersburg) with three samples 

each. A majority (16 of 23) of the highest unfiltered meth-

ylmercury concentrations were collected during changing 

streamflow hydrograph conditions. 

The two highest methylation efficiencies (appendix 6) 

were 24.6 percent and 23.5 percent, in samples from station 6 

(Mill Creek at tailwater pool near Manhattan), which also had 

the most values higher than 9.9 percent (the 90th percentile). 

Most of the methylation efficiencies in the 90th percentile 

were in samples from low and medium flow. Methylation 

efficiency was less than 5 percent in 63 percent of the 187 

samples.

10 The 90th percentile is the top one-tenth of a group of values that are rank 

ordered from highest to lowest.
24 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Concentrations That Exceeded a Standard

Unfiltered total mercury concentrations equaled or 

exceeded the 12 ng/L Indiana chronic aquatic criterion in 

5.8 percent of samples (13 of 225) and at 10 of the 25 monitoring stations (table 8, fig. 9). A majority (9 of 13) of the 

samples with concentrations that equaled or exceeded the 

12 ng/L criterion were collected during winter and spring 

(March 2006 and May 2006). These 13 samples were divided 

among stations in the White River System (6), Wabash River 

System (3), Great Lakes System (3), and Illinois River System 

(1). All but one of these samples was collected during changing streamflow hydrograph conditions; one was collected 

during stable, high streamflow. Most of the samples (12 of 

13) with concentrations that equaled or exceeded the 12 ng/L 

criterion were collected during high or event streamflow. 

Unfiltered total mercury concentrations were less than or equal 

to 12 ng/L in all 43 samples collected during low streamflow. 

Of the 10 monitoring stations where mercury concentrations 

equaled or exceeded the 12 ng/L criterion, five were downstream from rural and agricultural land use and five were 

downstream from urban and industrial wastewater discharges. 

The proportion of samples in which total mercury equaled or 

exceeded the 12 ng/L criterion was slightly higher between 

August 2004–September 2006 (5.8 percent) than in samples 

collected at most of these stations by the IDEM during 

2002–2004, (4.9 percent).

Unfiltered total mercury concentrations equaled or 

exceeded the most conservative Indiana water-quality criterion of 1.3 ng/L in 73 percent of samples, or 170 of 225. Of 

the 170 samples with concentrations that equaled or exceeded 

1.3 ng/L, 102 were collected during spring and summer and 

68 were collected during fall and winter. All nine samples collected August 2004–September 2006 at eight stations (figs. 1 

and 2) equaled or exceeded 1.3 ng/L—stations 5, 14, 16, and 

25 in the Wabash River System, stations 7 and 15 in the White 

River System, and stations 19 and 23 in the Great Lakes System (where 1.3 ng/L is the applicable water-quality criterion). 

Five of these stations are downstream from urban and industrial wastewater discharges; stations 14 and 16 are downstream 

from active and abandoned mine lands, and station 23 is 

downstream from urbanized land use (table 3).

Table 8. Monitoring stations with unfiltered total mercury concentrations that equaled or exceeded the Indiana chronic aquatic 

criterion for mercury, August 2004–September 2006.

[Indiana chronic aquatic criterion for mercury is 12 ng/L; ng/L, nanograms per liter]

Monitoring

station 

number

Station name

Date of sample 

collection

(month/day/year)

Unfiltered

 total 

mercury 

(ng/L)

Streamflow 

hydrograph 

condition

Streamflow 

statistical 

category

Hydrologic 

system Season

1 Fall Creek near Fortville 03/10/2006 21.2 Rising Event flow White River Winter.

2 Eel River near Logansport 08/30/2004 14.7 Falling Event flow Wabash River Summer.

7 White River near Centerton 05/16/2006 17.8 Falling Event flow White River Spring.

11 Vernon Fork Muscatatuck River at 

Vernon

03/09/2006 16.2 Rising Event flow White River Winter.

12 White River at State Road 258 near 

Seymour

03/09/2006 20.1 Rising High flow White River Winter.

12 White River at State Road 258 near 

Seymour

05/11/2006 17.9 Rising High flow White River Spring.

14 Patoka River at Winslow 10/28/2004 16.0 Falling High flow Wabash River Fall.

15 White River at Petersburg 10/28/2004 12.0 Falling Low flow White River Fall.

18 Wabash River at County Road 200 

West near Huntington

03/13/2006 15.0 Stable high High flow Wabash River Winter.

19 Maumee River at New Haven 03/14/2006 26.9 Rising Event flow Great Lakes Winter.

19 Maumee River at New Haven 05/23/2006 23.6 Rising High flow Great Lakes Spring.

19 Maumee River at New Haven 08/29/2006 12.5 Falling High flow Great Lakes Summer.

24 Kankakee River at Shelby 03/16/2006 12.2 Rising Event flow Illinois River Winter.
2

19

18

1

11

12

14

15

7

MICHIGAN

ILLINOIS OHIO

KENTUCKY

INDIANA

EXPLANATION

Monitoring station for 

mercury in Indiana streams

7

17.8

17.8

14.7

21.2

15.0

26.9

16.0

12.0

20.1 16.2

17.9

23.6 12.5

24

12.2

Drainage area upstream 

from monitoring station

Station number

Concentration of unfiltered

total mercury, in nanograms

per liter

88°

38°

39°

40°

41°

87° 86° 85°

Base from U. S. Geological Survey digital data 1:100,000 1983

Universal Transverse Mercator projection zone 16

North American Datum of 1983 (NAD 83)

0 30 60

0 30 60 KILOMETERS

MILES

Total Mercury and Methylmercury in Indiana Streams 25

Figure 9. Locations of monitoring stations with unfiltered total mercury concentrations that equaled or exceeded 

the Indiana chronic aquatic criterion for mercury, August 2004–September 2006.
26 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

The monitoring station with mercury concentrations that 

exceeded the 12 ng/L and 1.3 ng/L standards most frequently 

was station 19, Maumee River at New Haven, (figs. 1 and 2) 

in the Great Lakes System, including the two highest concentrations measured August 2004–September 2006 of 26.9 and 

23.6 ng/L. Five samples were collected during stable conditions; four samples were collected during changing streamflow 

hydrograph conditions, including samples with the three highest concentrations. Station 19 is downstream from urban and 

industrial wastewater discharges (table 3). 

Particulate Mercury

Unfiltered mercury is a combination of mercury adsorbed 

to and entrained in suspended particles (“particulate mercury”) 

and mercury dissolved in the water. With the methods used in 

this study, mercury dissolved in the water is measured in water 

passed through a 0.7-μm nominal pore-size filter. Therefore, 

in this report, particulate mercury is adsorbed to and entrained 

in particles larger than 0.7 μm, which includes nearly all sand, 

silt, and clay suspended sediment particles because only very 

fine clay is smaller than 0.7 μm (Horowitz, 1991). 

Generally, most of the total mercury in the August 

2004–September 2006 samples was estimated to be particulate. The median particulate fraction was 78 percent for 

samples with total mercury concentrations that equaled or 

exceeded the 12 ng/L Indiana chronic aquatic criterion and 

73 percent for samples with total mercury concentrations that 

equaled or exceeded the 1.3 ng/L Indiana criterion. Among the 

225 samples, 84 samples had more than 75 percent particulate total mercury and 15 samples had more than 90 percent. 

Particulate methylmercury was estimated in 172 of the 

225 samples. Of these, 87 samples had more than 75 percent 

particulate methylmercury and 71 samples had 100 percent 

particulate methylmercury. 

Generally, the fraction of unfiltered total mercury that 

was estimated to be particulate mercury increased as the turbidity in the water at the time of sample collection increased, 

as shown in the scatter plot in figure 10. The turbidity of the 

water samples was classified by range, and the estimated particulate total mercury concentrations were graphed as boxplots 

for these ranges (fig. 10). The median estimated particulate 

total mercury in ranges of turbidity more than 20 nephelometric turbidity ratio units (ntru) was higher than the 1.43 ng/L 

median estimated particulate total mercury in all samples at 

the 25 stations. In addition, the highest estimated particulate total mercury of more than 12 ng/L, the Indiana chronic 

aquatic criterion, was in samples with the highest turbidity.

Estimated particulate total mercury and turbidity were 

significantly higher when streamflow at the time of sample 

collection was in the high or event statistical category11

rather than the low or medium statistical category (KruskalWallis test, p < 0.0001 and Tukey’s test). Median estimated 

particulate total mercury was 1.90 ng/L for high streamflow 

and 3.85 ng/L for event streamflow (fig. 11), exceeding the 

most conservative Indiana water-quality criterion of 1.3 ng/L. 

Median turbidity at the time of sample collection was 21 ntru 

for high streamflow and 48 ntru for event streamflow (fig. 11).

Dams impede streamflow, causing suspended particles 

to settle and turbidity to decrease. Mercury concentrations 

were examined in a group of five monitoring stations (6, 10, 

17, 18, and 23, figs. 1 and 2, table 3) located within 2.7 miles 

downstream from dams. The unfiltered total mercury, particulate mercury, and the unfiltered and filtered methylmercury 

concentrations in 45 samples at monitoring stations downstream from dams were significantly lower12 than those in 

171 samples from stations not downstream from dams13. For 

example, the median unfiltered total mercury was 1.74 ng/L 

and 50 percent particulate in samples at stations downstream 

from dams, compared with 2.61 ng/L and 72 percent particulate in the samples from the stations not downstream from 

dams. Streamflow for samples at stations downstream from 

dams had a median of 141 ft3/s and was significantly lower13

than the streamflow for samples not downstream from dams, 

where the median was 621 ft3/s. 

11 Streamflow statistical category, for purposes of this report, was based 

on the daily mean streamflow record from the USGS streamflow-gaging 

station near each monitoring station, for water years 2004–2006 (October 1, 

2003 through September 30, 2006). For five stations, the gage height record 

was used instead of streamflow. Statistical categories were based on the rank 

ordered streamflow (or gage-height) data for a monitoring station, and are 

defined as low (less than or equal to the 10th percentile), medium (greater 

than the 10th percentile to equal to the median), high (greater than the median 

to equal to the 90th percentile), and event (greater than the 90th percentile). 

Instantaneous streamflow at the time of sample collection was placed in one 

of these four statistical categories. Station 16 was not assigned a streamflow 

statistical category because data were not available.

12 The Wilcoxon rank-sum test was computed to examine differences in 

mercury and methylmercury concentrations and streamflow from stations 

downstream and not downstream from dams (unfiltered total mercury, 

p = 0.003; unfiltered methylmercury, p = 0.001; filtered total mercury, 

p=0.284; filtered methylmercury, p <0.001; percent particulate total mercury, 

p<0.001; particulate total mercury, p<0.001, and streamflow, p<0.001). 

13 Station 22 was frequently affected by flow stagnation and flow reversals 

influenced by conditions in nearby Lake Michigan, and was excluded from 

this analysis
x

x

x

xx

o

o

o o

o

o

o

o

x

x

x x

o

x

RANGES OF TURBIDITY IN WATER SAMPLES AT TIME OF COLLECTION,

IN NEPHELOMETRIC TURBIDITY RATIO UNITS

0 - 10 11 - 20 21 - 30 31 - 40 41 -50 51 - 60 61 - 70 71 - 80

20

15

10

5

0

81 -100 110-200 210-500

ESTIMATED PARTICULATE TOTAL MERCURY CONCENTRATION,

IN NANOGRAMS PER LITER

73 50 19 20 13 9 7 3 7 8 6

EXPLANATION 

x

o

Whisker includes adjacent 

values within 1 step above box 

75th percentile (top of box)

Median (50th percentile)

25th percentile (bottom of box)

Whisker includes adjacent 

values within 1 step below box 

Upper detached values more

than 2 steps above box

Upper outside values within

1 to 2 steps above box

(Box height is variation or spread of data 

values, also called the interquartile range; 

1 step equals 1.5 times the height of the box)

25-station median estimated

total particulate mercury 

concentration,

August 2004--September 2006 

(1.43 nanograms per liter)

Indiana water-quality chronic 

aquatic criterion

 (12 nanograms per liter)

9 Number of samples

10 100

.10

1.0

10

.04

.05

.06

.07

.08

.20

.30

.40

.50

.60

.70

.80

2

3

4

5

6

7

8

20

30

TURBIDITY IN WATER SAMPLES AT TIME OF COLLECTION, IN NEPHELOMETRIC TURBIDITY RATIO UNITS

ESTIMATED PARTICULATE TOTAL MERCURY CONCENTRATION,

IN NANOGRAMS PER LITER

 1.0 2 3 4 5 6 7 8 20 30 40 50 60 70 80 200 300 400 500

EXPLANATION 

LOWESS

Locally Weighted

Scatterplot

Smoothing line

Data point

25

Total Mercury and Methylmercury in Indiana Streams 27

Figure 10. Estimated total particulate mercury and turbidity in water at the time of sample collection at 25 monitoring stations in 

Indiana, August 2004–September 2006.
LOW MEDIUM HIGH EVENT

ESTIMATED PARTICULATE TOTAL MERCURY, IN NANOGRAMS PER LITER

STREAMFLOW STATISTICAL CATEGORY

o

x

x

oo

o

o

x

o

x

43 89 58 26

0

5

10

15

20

x x

x

xx

o

o

o

o

x

o

o

o

x

o

43 89 57 26

LOW MEDIUM HIGH EVENT

STREAMFLOW STATISTICAL CATEGORY

TURBIDITY AT THE TIME OF SAMPLE COLLECTION, 

IN NEPHELOMETRIC TURBIDITY RATIO UNITS

500

400

300

200

100

0

EXPLANATION 

x

o

Whisker includes adjacent 

values within 1 step above box 

75th percentile (top of box)

Median (50th percentile)

25th percentile (bottom of box)

Whisker includes adjacent 

values within 1 step below box 

Upper detached values more

than 2 steps above box

Upper outside values within

1 to 2 steps above box

(Box height is variation or spread of data 

values, also called the interquartile range; 

1 step equals 1.5 times the height of the box)

 Streamflow Statistical Category

 for instantaneous streamflow at

 the time of sample collection

Ranking daily mean streamflow at USGS

streamflow-gaging station near each

mercury monitoring station, from

October 1, 2003 through September 30, 2006

 LOW - less than or equal to 

 the 10th percentile

MEDIUM - greater than 10 percentile 

 to equal to median

 HIGH - greater than median 

 to equal to 90th percentile

 EVENT - greater than 90th percentile 

26 Number of samples represented

by box

PARTICULATE TOTAL MERCURY

TURBIDITY

25

600

28 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 11. Estimated total particulate mercury and turbidity in water at the time of sample collection by streamflow statistical 

category for 24 monitoring stations on Indiana streams, August 2004–September 2006.
Total Mercury and Methylmercury in Indiana Streams 29

The observation in this study that higher total mercury 

and estimated particulate mercury concentrations correspond 

to higher streamflow and turbidity (representing suspended 

particles) is similar to observations in previous investigations. The correlations of particulate mercury, streamflow, and 

suspended particles were reported in a study of Lake Michigan 

tributaries from 1994 (Hurley and others, 1998), a study of a 

watershed in Vermont from 2000 (Shanley and others, 2002), 

and a study of the Grand Calumet River in Indiana, 2001–

2002 (Risch, 2005).

Concentrations in Relation to Sampling 

Locations and Upstream Drainage Areas 

Distributions of unfiltered total mercury and unfiltered 

methylmercury concentrations in the nine samples at each 

monitoring station during August 2004–September 2006 are 

displayed in box plots (fig. 12). The plots in fig. 12 show six 

stations (5, 7, 14, 15, 19, and 25) had the highest distribution of total mercury concentrations, and the 25th percentile 

for those stations and at least seven of the nine samples 

were higher than the 2.35 ng/L median for all stations. All 

54 unfiltered total mercury concentrations at these 6 stations 

were higher than the most conservative Indiana water-quality 

criterion (1.3 ng/L), and 6 concentrations were higher than the 

12 ng/L Indiana chronic aquatic criterion. The plots in fig. 12 

show five stations (8, 15, 16, 19, and 25) had the highest distribution of methylmercury concentrations14, and the 25th percentile at those stations and at least seven of the nine samples 

were higher than or equal to the 0.09 ng/L median for all stations. Station 25 had the most methylmercury concentrations 

(nine of nine) higher than the 0.09 ng/L median. It should be 

noted that stations 5, 6, 7, 12, and 18 had five or six concentrations higher than the statewide median and had medians, 75th 

percentiles, and maximums that were higher than station 8. 

On the basis of having at least 7 of 9 unfiltered total mercury 

and unfiltered methylmercury concentrations higher than the 

statewide median, three stations had the highest distributions 

(15, 19, and 25, figs. 1 and 2), but stations 5 and 7 could be 

included in this group too when their overall methylmercury 

concentrations were considered. By either rating, it can be 

observed that these three or five stations were downstream 

from urban and industrial wastewater discharges (table 3).

For descriptive purposes, samples were grouped by the 

size of their drainage areas (table 2) upstream from the 25 

monitoring stations—large (more than 10,000 mi2), medium 

(1,000 to 10,000 mi2), and small (less than 1,000 mi2). The 

unfiltered mercury concentrations (table 9) were compared 

14 Concentrations less than the 0.04 ng/L reporting limit were set to one-half 

of the reporting limit for the plots in figure 12.

for each group. It was observed that the median unfiltered 

total mercury and methylmercury concentrations and median 

streamflow were highest in the samples from the large drainage areas. All of the total mercury concentrations from samples in the large drainage areas equaled or exceeded the most 

conservative Indiana water-quality criterion, 1.3 ng/L. The 

medium drainage areas had the highest proportion (13 percent) 

of the samples with total mercury concentrations that equaled 

or exceeded the 12 ng/L standard, compared with 3.7 percent 

from the large drainage areas and 3.4 percent from the small 

drainage areas. 

Seasonal Variations in Concentrations

The 225 water samples from Indiana streams were collected from summer 2004 through summer 2006. Distributions of unfiltered total mercury and unfiltered methylmercury 

concentrations in these samples during the four temperate 

seasons (winter, spring, summer, and fall) were displayed 

in box plots (fig. 13) and examined statistically. A KruskalWallis test was computed to examine differences among the 

distributions of unfiltered total mercury and methylmercury 

concentrations measured during each season. These comparisons indicate that unfiltered total mercury concentrations were 

significantly higher during spring than fall15. For example, the 

median spring unfiltered total mercury concentration was 2.56 

ng/L compared with a 1.36 ng/L median for fall. Most of the 

concentrations that equaled or exceeded the 12 ng/L Indiana 

chronic aquatic criterion were collected during winter and 

spring. The highest mercury concentrations correspond to high 

median streamflow and highest turbidity during spring (table 

10), which potentially could contribute to more transport of 

particulate mercury. Graphical (fig. 13) and statistical comparisons also indicate that unfiltered methylmercury concentrations were higher during spring and summer than winter and 

fall16. For example, the median spring and summer unfiltered 

methylmercury concentrations were 0.13 and 0.11 ng/L, compared with 0.07 and 0.05 ng/L for winter and fall. The highest methylmercury concentrations correspond to the highest 

median water temperatures during spring and summer (table 

10), which potentially could contribute to more microbially 

mediated formation of methylmercury.

15 The Kruskal-Wallis test confirmed statistically significant differences 

among seasons for unfiltered total mercury (p = 0.008). Tukey’s test indicated 

unfiltered total mercury was higher in spring than fall. Median values were 

compared to identify which season had higher values when they were statistically different.

16 The Kruskal-Wallis test confirmed the presence of statistically significant 

differences among seasons for unfiltered methylmercury (p < 0.001). Tukey’s 

test indicated unfiltered methylmercury was higher in spring and summer than 

winter.
x

o

o

o x

x

x

x

o

o

o

o

o

o

x

x

x

o

x o

o

o o

x

UNFILTERED TOTAL MERCURY, IN NANOGRAMS PER LITER

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

 MONITORING STATION FOR MERCURY IN INDIANA STREAMS

EXPLANATION 

x

o

Whisker includes adjacent 

values within 1 step above box 

75th percentile (top of box)

Median (50th percentile)

25th percentile (bottom of box)

Whisker includes adjacent 

values within 1 step below box 

Upper detached values more

than 2 steps above box

Upper outside values within

1 to 2 steps above box

(Box height is variation or spread of data 

values, also called the interquartile range; 

1 step equals 1.5 times the height of the box)

25-station median unfiltered

total mercury concentration,

August 2004--September 2006 

(2.35 nanograms per liter)

Mercury concentrations greater than

25th percentile exceed 25-station 

median concentration, 2004--2006

x

x

x

x

o

o

x

o

x

o

x

x

o

x

x

o

x

x

0

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

 MONITORING STATION FOR MERCURY IN INDIANA STREAMS

UNFILTERED METHYLMERCURY, IN NANOGRAMS PER LITER

25-station median unfiltered

methylmercury concentration,

August 2004--September 2006 

(0.09 nanograms per liter)

Indiana water quality chronic

aquatic criterion 

(12 nanograms per liter)

x

x

x

0.7

30

UNFILTERED TOTAL MERCURY

UNFILTERED METHYLMERCURY

30 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 12. Distributions of concentrations of unfiltered total mercury and unfiltered methylmercury in water samples at 25 monitoring 

stations in Indiana, August 2004–September 2006.
Total Mercury and Methylmercury in Indiana Streams 31

Table 9. Mercury concentrations and instantaneous streamflow for samples from Indiana streams, August 2004–

September 2006, grouped by drainage area upstream from monitoring station.

[mi2, square mile; ng/L, nanograms per liter; ft3/s, cubic foot per second; ≥, greater than or equal to; IWQC, Indiana water–quality criterion; 

NA, not applicable; RL, reporting limit; ––, no data]

Drainage area

upstream from

monitoring station

(mi2)

Number 

of 

samples

Descriptive

statistic

Unfiltered total 

mercury

(ng/L)

Unfiltered

methylmercury

(ng/L)

Instantaneous 

streamflow1

(ft3/s)

Large—more than 10,000 27 Median 4.32 0.16 7,220

Minimum 1.95 .06 1,780

Maximum 12.0 .42 35,200

Number ≥12 ng/L IWQC 1 NA ––

Number ≥1.3 ng/L IWQC 27 NA ––

Number <0.04 ng/L RL 0 0 ––

Medium—1,000 to 10,000 54 Median 3.28 .10 1,270

Minimum .39 <.04 106

Maximum 26.9 .44 8,140

Number ≥12 ng/L IWQC 7 NA ––

Number ≥1.3 ng/L IWQC 46 NA ––

Number <0.04 ng/L RL 0 5 ––

Small—Less than 1,000 144 Median 1.74 .08 151

Minimum .24 <.04 49

Maximum 21.0 .57 3,730

Number ≥12 ng/L IWQC 5 NA ––

Number ≥1.3 ng/L IWQC 97 NA ––

Number <0.04 ng/L RL 0 33 ––

1

Small drainage area does not include streamflow from station 22, which was affected by flow reversals and flow stagnation.
x

x

x

x

o

xx

o

x

x

x

x

x

o

o x

x

x

x

x

o

WINTER

SPRING

SUMMER

FALL

50 50 75 50

37 48 70 32

WINTER

SPRING

SUMMER

FALL

9 Number of samples per season

EXPLANATION 

x

o

Whisker includes adjacent 

values within 1 step above box 

75th percentile (top of box)

Median (50th percentile)

25th percentile (bottom of box)

Whisker includes adjacent 

values within 1 step below box 

Upper detached values more

than 2 steps above box

Upper outside values within

1 to 2 steps above box

(Box height is variation or spread of data 

values, also called the interquartile range; 

1 step equals 1.5 times the height of the box)

25-station median unfiltered

total mercury concentration,

August 2004--September 2006 

(2.35 nanograms per liter)

25-station median unfiltered

methylmercury concentration,

August 2004--September 2006 

(0.09 nanograms per liter)

Statewide Indiana Water

Quality Standard (12 nanograms

per liter)

0.1

0.2

0.3

0.4

0.5

0.6

UNFILTERED METHYLMERCURY IN NANOGRAMS PER LITER

0

25

20

15

10

5

0

UNFILTERED TOTAL MERCURY IN NANOGRAMS PER LITER

AUGUST 2004 THROUGH SEPTEMBER 2006

AUGUST 2004 THROUGH SEPTEMBER 2006

x

x

x

o

x

x

x x

x

x

o

x

x

x

UNFILTERED TOTAL MERCURY

UNFILTERED METHYLMERCURY

30

0.7

32 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 13. Distributions of concentrations of unfiltered total mercury and unfiltered methylmercury in water samples during four 

seasons in Indiana, August 2004–September 2006.
Total Mercury and Methylmercury in Indiana Streams 33

Table 10. Median concentrations of mercury in water samples and median streamflow and median 

water–quality characteristics at the time of sample collection during four seasons in Indiana, 

August 2004–September 2006.

[ng/L, nanograms per liter; ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter; oC, degree Celsius; ntru, 

nephelometric turbidity ratio unit]

Parameter Winter Spring Summer Fall

Unfiltered total mercury (ng/L) 2.63 2.56 2.32 1.36

Unfiltered methylmercury (ng/L) .07 .13 .11 .05

Instantaneous streamflow1 (ft3/s) 1,340 553 172 361

pH (standard unit) 7.8 7.9 7.9 7.8

Specific conductance (μS/cm) 550 593 599 661

Water temperature (oC) 5.34 19.0 22.6 9.40

Turbidity (ntru) 17 20 15 9.6

1 Station 22 was frequently affected by flow stagnation and flow reversals influenced by conditions in nearby Lake 

Michigan; station 22 was therefore excluded from the statistics for streamflow.

Concentrations in Relation to Water-Quality 

Characteristics and Streamflow

Water-quality characteristics were measured at the time 

of sample collection (table 11 shows all monitoring stations, 

table 12 shows each monitoring station). In the following 

discussion, pH, specific conductance, and turbidity are summarized and compared with mercury concentrations.

Values of pH indicated neutral to alkaline waters and 

ranged from 7.0 to 8.7 standard units, with a median value of 

7.8 (table 11). Some differences in mercury concentrations 

were noted for groups of samples that had the lowest pH values (in the 10th percentile, less than or equal to 7.4 standard 

units) and the highest pH values (in the 90th percentile, more 

than or equal to 8.2 standard units). Station 14, Patoka River 

at Winslow (figs. 1 and 2), is downstream from active and 

abandoned mine lands and had the lowest median pH (7.2 

Table 11. Summary statistics for water–quality characteristics and streamflow in water samples from 25 monitoring stations in 

Indiana, August 2004–September 2006.

[μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; C, Celsius; ntru, nephelometric turbidity ratio unit]

Summary statistic

pH

(standard 

units)

Specific

conductance

(μS/cm)

Dissolved 

oxygen

(mg/L)

Water

temperature

(degrees C)

Turbidity

(ntru)

Streamflow1

(ft3)s)

Maximum 8.7 1,280 14.5 30.7 500 35,200

90th percentile 8.2 856 13.0 24.7 74 5,730

75th percentile 8.0 704 11.6 22.5 39 1800

50th percentile (median) 7.8 605 9.4 16.2 16 438

25th percentile 7.7 491 7.7 6.7 8 99

Minimum 7.0 180 4.4 –.3 1 4.9

1 Station 22 was frequently affected by flow stagnation and flow reversals influenced by conditions in nearby Lake Michigan; station 22 was therefore 

excluded from the statistics for streamflow.
34 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Table 12. Ranges and medians of water–quality characteristics and streamflow from 25 monitoring stations in Indiana, August 2004–September 2006.—Continued

[μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; oC, Celsius; ntru, nephelometric turbidity ratio unit; ft3/s. cubic foot per second]

Monitoring 

station 

number

pH

(standard

units)

Specific 

conductance

(μS/cm)

Dissolved 

oxygen

(mg/L)

Temperature

(oC)

Turbidity

(ntru)

Streamflow

(ft3/s)

Range Median Range Median Range Median Range Median Range Median Range Median

1 7.4–8.1 7.8 368–832 746 6.4–13.0 8.4 1.4–23.3 11.9 2.3–280 13 28–1,660 782 7.5–8.3 7.9 365–804 684 6.5–14.1 10.9 –0.2–22.6 13.6 1.5–140 5.7 115–3,730 3783 7.5–8.2 8.0 511–657 606 6.9–14.1 8.8 3.8–23.8 18.6 2.5–36 5.7 172–2,430 5974 7.6–8.3 8.0 607–866 681 7.8–13.3 9.6 –0.3–22.8 12.8 2.5–74 8.1 67–2,470 4095 7.8–8.7 8.0 508–663 597 5.5–13.8 11.2 5.3–30.7 19.3 32–73 39 2,130–26,700 7,2206 7.1–7.9 7.4 287–445 310 6.8–14.5 9.1 4.5–25.1 16.4 8.2–17 13 12–632 1137 7.4–8.2 7.8 561–1,280 999 7.2–11.7 9.7 4.1–26.4 17.9 6.9–60 15 570–7,480 9758 7.7–8.2 7.8 472–969 865 6.6–13.8 9.2 1.3–26.9 14.8 4.3–77 12 227–5,010 5169 7.7–8.2 7.9 508–728 632 7.1–14.0 9.6 0.6–25.7 12.9 4.3–33 6.0 9.3–346 21

10 7.6–8.3 7.8 418–503 472 7.7–13.8 10.2 3.9–21.8 13.4 1.1–14 2.9 50–2,010 307

11 7.4–8.4 7.9 180–729 385 6.5–13.9 8.9 1.8–26.7 14.3 2.5–180 9.3 4.9–2,030 65

12 7.7–8.3 7.9 334–709 640 7.5–13.3 9.4 3.2–27.5 16.2 5.2–290 9.9 362–6,740 1,09013 7.4–7.9 7.7 332–520 435 6.2–13.2 8.2 3.4–24.3 15.8 3.5–18 14 10–351 3314 7.1–7.5 7.2 235–626 350 5.2–12.7 7.5 4.4–25.9 17.1 15–240 48 47–1,240 31115 7.6–8.2 8.0 460–831 545 6.9–14.5 9.9 5.5–28.7 18.6 22–110 47 1,780–15,100 7,65016 7.2–8.0 7.6 603–1,280 863 5.4–12.2 7.3 3.2–24.1 17.0 14–57 27 14–244 8417 7.4–8.0 7.8 458–575 511 4.5–13.2 9.7 3.4–24.5 14.0 5.2–41 21 89–2,020 24818 7.5–8.2 7.9 478–708 591 7.5–13.5 10.1 0.6–28.1 15.7 26–280 46 25–2,290 13319 7.4–7.8 7.7 384–905 580 4.4–12.5 9.3 –0.1–24.5 14.5 22–500 68 106–8,140 1,30020 7.0–8.2 7.9 373–692 619 6.6–12.3 8.4 –0.2–20.9 14.0 4.4–98 21 6.4–592 5921 7.4–8.2 7.9 496–668 586 7.1–13.3 9.7 0.0–23.5 16.1 2.0–59 4.5 1,060–6,030 1,920
Total Mercury and Methylmercury in Indiana Streams 35

Table 12. Ranges and medians of water–quality characteristics and streamflow from 25 monitoring stations in Indiana, August 2004–September 2006.—Continued[μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; oC, Celsius; ntru, nephelometric turbidity ratio unit; ft3/s. cubic foot per second]

Monitoring 

station 

number

pH

(standard

units)

Specific 

conductance

(μS/cm)

Dissolved 

oxygen

(mg/L)

Temperature

(oC)

Turbidity

(ntru)

Streamflow

(ft3/s)

Range Median Range Median Range Median Range Median Range Median Range Median

22 7.5–8.2 7.8 610–854 757 7.5–13.7 9.4 2.1–21.7 14.0 4.1–45 9.9 –2821–583 4923 7.3–8.5 7.9 520–939 666 6.0–12.2 9.9 1.5–24 18.4 12–91 18 15–417 3624 7.7–8.0 7.8 522–766 662 7.4–12.7 8.7 –0.3–22.9 16.7 5.9–160 19 629–3,440 1,59025 7.6–8.6 8.2 487–629 597 7.7–14.5 11.6 4.4–28 18.8 24–98 49 2,340–35,200 6,050

1Instantaneous streamflow from station 22 includes positive values indicating a flow direction downstream toward nearby Lake Michigan and negative values indicating a flow direction upstream 

from Lake Michigan that were influenced by water levels in Lake Michigan.

standard units) and had eight pH values among the lowest pH 

of all samples. Median unfiltered total mercury in these eight 

samples at station 14 was 4.29 ng/L, higher than the median 

of 2.35 ng/L for all samples and the median of 3.29 ng/L for 

samples with the lowest pH. In contrast, median unfiltered 

total mercury was 1.49 ng/L in the samples with the highest 

pH values. 

Values of specific conductance ranged from 180 to 

1,280 μS/cm, with a median of 605 μS/cm (table 11). Median 

specific conductance was highest during fall, 661 μS/cm, 

and lowest during winter, 550 μS/cm (table 10). Most of the 

samples that had the highest specific conductance (in the 90th 

percentile, more than or equal to 857 μS/cm) were at station 

7, White River at Centerton (seven samples), station 8, White 

River near Nora (six samples), and station 16, Busseron Creek 

near Carlisle (six samples). These three stations (figs. 1 and 2) 

also had the highest median specific conductance for August 

2004–September 2006; median specific conductance was 

999 μS/cm at station 7, 865 μS/cm at station 8, and 863 μS/cm 

at station 16. The median unfiltered total mercury at station 7 

was 6.34 ng/L, which is higher than the median unfiltered total 

mercury of 2.55 ng/L at station 8 and 2.49 ng/L at station 16. 

Station 7 is downstream from urban and industrial wastewater 

discharges (table 3), which potentially could contribute to its 

high specific conductance and unfiltered total mercury. Most 

of the samples with the lowest specific conductance (in the 

10th percentile, less than 377 μS/cm) were at station 6, Mill 

Creek at tailwater pool near Manhattan, and station 14, Patoka 

River at Winslow. 

Values of turbidity ranged from 1.1 to 500 ntru, with a 

16 ntru median (table 11). Median turbidity differed substan-

tially among seasons (table 10), and it was highest during 

spring (20 ntru). As noted previously, the median fraction of 

total mercury that was estimated to be particulate increased in 

ranges of turbidity greater than 20 ntru, where turbidity poten-

tially could indicate more transport of particulate mercury 

(fig. 11). The samples with the highest turbidity (in the 90th 

percentile, greater than or equal to 74 ntru) include most of 

the highest unfiltered total mercury concentrations. Stated in 

another way, 15 of the 23 highest unfiltered total mercury con-

centrations were in samples with the highest turbidity values 

(table 13). Station 19, Maumee River at New Haven, had the 

most samples with high turbidity.

Streamflow17 ranged from 4.9 to 35,200 ft

3

/s, with a 

median of 438 ft

3

/s. Median streamflow differed substantially 

among seasons (table 10), and it was highest during winter. 

Median mercury concentrations and methylation efficiency 

were related to streamflow statistical category (table 14), as 

described in the following discussion.

17 Station 22, Trail Creek at Michigan City Harbor was frequently affected 

by flow stagnation and flow reversal influenced by conditions in nearby Lake 

Michigan and was therefore excluded from summary statistics for streamflow.
36 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Table 13. Highest unfiltered total mercury concentrations in water samples from Indiana streams, August 2004–September 2006, and 

turbidity at the time of sample collection.

[ng/L, nanograms per liter; ntru, nephelometric turbidity ratio unit]

Monitoring

station

number

Station name

Date of sample 

collection

(month/day/year)

Unfiltered total 

mercury 

(ng/L)

Turbidity 

(ntru)

Turbidity

in 90th

percentile

19 Maumee River at New Haven 03/14/2006 26.9 500 Yes.

19 Maumee River at New Haven 05/23/2006 23.6 68 No.

1 Fall Creek near Fortville 03/10/2006 21.2 280 Yes.

12 White River at State Road 258 near Seymour 03/09/2006 20.1 290 Yes.

12 White River at State Road 258 near Seymour 05/11/2006 17.9 260 Yes.

7 White River near Centerton 05/16/2006 17.8 60 No.

11 Vernon Fork Muscatatuck River at Vernon 03/09/2006 16.2 180 Yes.

14 Patoka River at Winslow 10/28/2004 16.0 240 Yes.

18 Wabash River at County Road 200 West near 

Huntington

03/13/2006 15.0 280 Yes.

2 Eel River near Logansport 08/30/2004 14.7 140 Yes.

19 Maumee River at New Haven 08/29/2006 12.5 92 Yes.

24 Kankakee River at Shelby 03/16/2006 12.2 160 Yes.

15 White River at Petersburg 10/28/2004 12.0 110 Yes.

5 Wabash River at U.S. Highway 40 at Terre Haute 11/03/2004 11.6 69 No.

8 White River near Nora 03/10/2006 11.3 77 Yes.

14 Patoka River at Winslow 11/30/2005 10.3 160 Yes.

7 White River near Centerton 10/14/2004 10.1 20 No.

25 Wabash River at Vigo Street at Vincennes 11/04/2004 9.73 93 Yes.

19 Maumee River at New Haven 03/08/2005 9.64 110 Yes.

8 White River near Nora 05/15/2006 9.51 59 No.

19 Maumee River at New Haven 08/30/2005 9.28 31 No.

7 White River near Centerton 08/24/2004 9.10 15 No.

21 St. Joseph River at Elkhart 03/15/2006 9.05 59 No.
Total Mercury and Methylmercury in Indiana Streams 37

Unfiltered total mercury was significantly higher when 

streamflow at the time of sample collection was in the high 

or event statistical category18 rather than the low or medium 

statistical category (Kruskal-Wallis test, p < 0.001 and Tukey’s 

test). Median unfiltered total mercury was 3.29 ng/L for high 

streamflow and 7.02 ng/L for event streamflow (fig. 14). Unfiltered total mercury concentrations that exceeded the Indiana 

water-quality chronic aquatic criterion of 12 ng/L were all 

from samples collected during high or event streamflow. Unfiltered methylmercury was not significantly different among 

the streamflow statistical categories (Kruskal-Wallis test, 

18 Streamflow statistical category, for purposes of this report, was based 

on the daily mean streamflow record from the USGS streamflow-gaging 

station near each monitoring station, for water years 2004–2006 (October 1, 

2003 through September 30, 2006). For five stations, the gage height record 

was used instead of streamflow. Statistical categories were based on the rank 

ordered streamflow (or gage-height) data for a monitoring station, and are 

defined as low (less than or equal to the 10th percentile), medium (greater 

than the 10th percentile to equal to the median), high (greater than the median 

to equal to the 90th percentile), and event (greater than the 90th percentile). 

Instantaneous streamflow at the time of sample collection was placed in one 

of these four statistical categories. Station 16 was not assigned a streamflow 

statistical category because data were not available.

p = 0.15). However, methylation efficiency was significantly 

higher if streamflow at the time of sample collection was in 

the low or medium statistical category rather than the high or 

event statistical category (Kruskal-Wallis test, p < 0.001 and 

Tukey’s test). Median methylation efficiency was 6 percent 

for low streamflow and 4.7 percent for medium streamflow 

(fig. 14). As noted previously, the median fraction of total 

mercury that was estimated to be particulate mercury was 

highest during high and event streamflow, when streamflow 

potentially could contribute to more transport of particulate 

mercury (fig. 11). 

Table 14. Median mercury concentrations and methylation efficiency in water samples from Indiana streams, 

August 2004–September 2006, by streamflow statistical category.

[Streamflow statistical category for 216 samples, excluding 9 samples from station 16; ng/L, nanograms per liter]

Streamflow 

statistical 

category

Median

unfiltered

total mercury

(ng/L)

Median

unfiltered

methylmercury

(ng/L)

Median

estimated

particulate

total mercury

(ng/L)

Median

estimated 

particulate 

methylmercury

(ng/L)

Median 

methylation 

efficiency

(percent)

Low flow 1.56 0.10 1.11 0.06 6.0

Medium flow 1.82 .09 1.08 .05 4.7

High flow 3.29 .09 1.90 .09 2.4

Event flow 7.02 .14 3.85 .08 2.0
x

x

x

xx

x

o

o

o

x

x

x

x

15

20

25

43 89 58 26

LOW MEDIUM HIGH EVENT

UNFILTERED TOTAL MERCURY, IN NANOGRAMS PER LITER

5

0

STREAMFLOW STATISTICAL CATEGORY

x

x

x

x

xx

x

x

o

o

x

x

39 67 48 24

LOW MEDIUM HIGH EVENT

STREAMFLOW STATISTICAL CATEGORY

METHYLATION EFFICIENCY, IN PERCENT 

(UNFILTERED METHYLMERCURY / UNFILETERED TOTAL MERCURY)

0

5

10

15

20

25

EXPLANATION 

x

o

Whisker includes adjacent 

values within 1 step above box 

75th percentile (top of box)

Median (50th percentile)

25th percentile (bottom of box)

Whisker includes adjacent 

values within 1 step below box 

Upper detached values more

than 2 steps above box

Upper outside values within

1 to 2 steps above box

(Box height is variation or spread of data 

values, also called the interquartile range; 

1 step equals 1.5 times the height of the box)

 Streamflow Statistical Category

 for instantaneous streamflow at

 the time of sample collection

Ranking daily mean streamflow at USGS

streamflow-gaging station near each

mercury monitoring station, from

October 1, 2003 through September 30, 2006

 LOW - less than or equal to 

 the 10th percentile

MEDIUM - greater than 10 percentile 

 to equal to median

 HIGH - greater than median 

 to equal to 90th percentile

 EVENT - greater than 90th percentile 

26 Number of samples represented

by box

10

Indiana water quality chronic

aquatic criterion 

(12 nanograms per liter)

UNFILTERED TOTAL MERCURY

METHYLATION EFFICIENCY

30

30

38 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Figure 14. Unfiltered total mercury and methylation efficiency by streamflow statistical category, for 24 monitoring stations on Indiana 

streams, August 2004–September 2006.
Summary 39

Summary

A monitoring program for mercury in Indiana streams 

was operated by the U.S. Geological Survey (USGS) in 

cooperation with the Indiana Department of Environmental 

Management (IDEM). Total mercury and methylmercury 

concentrations were determined by use of low (subnanogram 

per liter) level analytical methods in 225 representative water 

samples collected following ultraclean protocols at 25 stations 

in a statewide monitoring network, August 2004–September 

2006. These samples represent the major hydrologic systems 

in Indiana and were collected during multiple seasons and a 

range of streamflow conditions. Data from 89 quality-control 

samples indicated there were few, if any, biases in the mercury concentrations caused by artifacts from sampling and 

processing or interference from the sampling matrix and that 

precision of the reported concentrations was not substantially 

affected by natural variability or variability from sampling and 

processing.

Unfiltered total mercury ranged from 0.24 to 26.9 ng/L, 

with a median of 2.35 ng/L. The highest concentrations (in 

the 90th percentile) of unfiltered total mercury were more 

than 9.05 ng/L, and the majority of these concentrations were 

from samples collected during winter and spring 2006 during 

changing streamflow hydrograph conditions. Samples with 15 

of the 23 highest unfiltered total mercury concentrations had 

the highest turbidity values, greater than or equal to 74 ntru, 

at the time of sample collection. Streamflow at the time of 

sample collection for most of the highest concentrations was 

in the high or event statistical category.

 Unfiltered methylmercury was detected in 83 percent 

of samples, and reported concentrations ranged from 0.04 to 

0.57 ng/L, with a median of 0.09 ng/L. The highest concentrations of methylmercury were more than 0.25 ng/L, and most 

of these samples were collected during spring and summer 

during changing streamflow hydrograph conditions.

Unfiltered total mercury concentrations equaled or 

exceeded the Indiana chronic aquatic criterion of 12 ng/L in 

5.8 percent of the samples and at 10 of the 25 monitoring stations. Of the 13 samples with concentrations that equaled or 

exceeded this criterion, most were collected during winter and 

spring 2006 during changing streamflow hydrograph conditions. Of the 10 monitoring stations where mercury concentrations equaled or exceeded the 12 ng/L criterion, 5 were 

downstream from urban and industrial wastewater discharges 

and 5 were downstream from rural and agricultural land use. 

Unfiltered total mercury concentrations equaled or exceeded 

the most conservative Indiana water-quality criterion of 

1.3 ng/L in 73 percent of samples.

Particulate mercury concentrations were estimated in 

these samples by subtracting the filtered concentration from 

the unfiltered concentration. Generally, most of the total 

mercury that equaled or exceeded the 12 ng/L Indiana chronic 

aquatic criterion and the 1.3 ng/L Indiana water-quality criterion was particulate, which is defined as greater than 0.7 μm 

in diameter, the size of very fine clay. The median fraction of 

unfiltered mercury that was particulate was highest in samples 

in which turbidity was more than 20 ntru and when streamflow at the time of sample collection was in the high or event 

statistical category.

Methylation efficiencies were computed for 187 samples 

with reported concentrations of both unfiltered total and unfiltered methylmercury. Methylation efficiencies ranged from 

0.4 to 24.6 percent, with a median of 3.7 percent. Methylation 

efficiency was less than 5.0 percent in 63 percent of samples. 

Four of the highest methylation efficiency values, including 

the two highest values (23.5 and 24.6 percent), were from 

samples collected at station 6—Mill Creek at tailwater pool 

near Manhattan. The highest methylation efficiencies (21 of 

23) were in samples collected when streamflow was in the low 

and medium statistical categories.

Samples from six stations had the highest distribution 

of total mercury concentrations—at least seven of the nine 

samples for these stations were greater than the 2.35 ng/L 

median for all stations. These stations were station 5, Wabash 

River at U.S. Highway 40 at Terre Haute; 7, White River near 

Centerton; 14, Patoka River at Winslow; 15, White River at 

Petersburg; 19, Maumee River at New Haven; and 25, Wabash 

River at Vigo Street at Vincennes. With the exception of station 14, all of these stations were downstream from urban and 

industrial wastewater discharges in upstream drainage areas 

of more than 1,960 mi2. Station 14 is downstream from active 

and abandoned mine lands in an upstream drainage area of 

602 mi2.

The monitoring station with mercury concentrations that 

exceeded the 12 ng/L and 1.3 ng/L Indiana water-quality criterion most frequently was station 19, Maumee River at New 

Haven, and the two highest unfiltered total mercury concentrations, 26.9 and 23.6 ng/L, were in samples from this station. 

Station 19 had the most methylmercury concentrations greater 

than the 0.09 ng/L median for all samples, the most samples 

with the highest turbidity (more than or equal to 74 ntru), and 

the sample with the highest turbidity (500 ntru). Station 19 is 

downstream from urban and industrial wastewater discharges. 

Samples at station 7, White River near Centerton, had a 

median of 6.34 ng/L total mercury, the highest median specific 

conductance of 999 μS/cm, and seven of the highest specific 

conductance values for all samples. Station 7 also is downstream from urban and industrial wastewater discharges. 

Unfiltered total mercury concentrations were statistically 

higher during spring than fall. High median instantaneous 

streamflow and turbidity potentially indicate conditions for the 

most transport of particulate mercury. Methylmercury concentrations were statistically higher during spring and summer 

than during winter. High median water temperatures in these 

seasons potentially indicate conditions for the most microbially mediated formation of methylmercury.

At five monitoring stations located within 2.7 miles 

downstream from dams, concentrations of unfiltered total 

mercury, particulate mercury, and the unfiltered and filtered 

methylmercury were significantly lower than at stations not 
40 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

downstream from dams. Streamflow for samples at stations 

downstream from dams was significantly lower as well.

The results from monitoring of total mercury and 

methylmercury in Indiana streams, August 2004–September 

2006, are presented with results from previous studies in the 

following comparisons. In general, the results from August 

2004–September 2006 do not differ substantially from results 

of studies in Indiana and other states during 1994–2004.

• The median concentration of unfiltered total mercury 

of 2.35 ng/L in 225 samples, August 2004–September 

2006, was similar to median unfiltered total mercury 

of 2.23 ng/L in 187 samples collected by the IDEM, 

2002–2004. The range of concentrations of 0.24 to 

26.9 ng/L during August 2004–September 2006 and 

0.19 to 28.1 ng/L during 2002–2004 also was similar. 

Median total mercury, August 2004–September 2006, 

was similar to the median for the nationwide study 

in 1998 of 2.3 ng/L and slightly less than the median 

of 2.6 ng/L from the statewide study in Wisconsin, 

1993–1994.

• The proportion of samples from Indiana streams 

in which total mercury equaled or exceeded the 12 

ng/L chronic aquatic criterion was 5.8 percent and 

was slightly higher in August 2004–September 2006 

than in samples collected by the IDEM, 2002–2004, 

4.9 percent.

• The median concentration of unfiltered methylmercury in 187 samples, August 2004–September 2006, 

was 0.09 ng/L, which was nearly one-half the median 

methylmercury of 0.17 ng/L in 65 samples collected by 

the IDEM, 2002–2004. Median methylmercury, August 

2004–September 2006, was slightly higher than the 

median of 0.06 ng/L for the nationwide study in 1998 

and slightly less than the median of 0.11 ng/L from the 

statewide study in Wisconsin, 1993–1994.

• Median methylation efficiencies of 3.7 percent between 

August 2004–September 2006 and 3.6 percent in 

2002–2004 were similar, but both medians were higher 

than the median of 0.6 percent for the Grand Calumet 

River/Indiana Harbor Canal in Indiana in 2001–2002.

• In this study from August 2004 through September 

2006, it was observed that higher total mercury and 

particulate mercury concentrations correspond to 

higher instantaneous streamflow and turbidity (representing suspended particles). This observation is 

similar to the correlations of particulate mercury, 

streamflow, and suspended particles reported in a study 

of Lake Michigan tributaries from 1994, and a study of 

the Grand Calumet River in Indiana, 2001–2002.

Acknowledgments

The authors acknowledge the capable assistance and technical support of Tim Beckman of the IDEM Office of Water 

Management, who participated in most of the field activities of 

the monitoring. Art Garceau, Dennis Clark, and Steve Boswell 

of the IDEM Office of Water Management designed the monitoring network. Mark Olson and John DeWild of the USGS 

Mercury Research Laboratory provided extensive technical 

support regarding sample preparation and data management. 

Richard Duwelius, Tim Willoughby, Bret Robinson, and Lee 

Watson of the USGS Indiana Water Science Center were key 

to the scientific techniques, safety, and logistics used in the 

monitoring. The authors are most grateful to Scott Lowe, 

Cheryl Silcox, Kathleen Fowler and Don Leer of the USGS 

Indiana Water Science Center, who helped collect and process 

the more than 300 water samples and quality-control samples 

described in this report.

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Appendixes 43

Appendixes 1–7

1. Total mercury concentrations in quality-control field-blank samples 

from mercury monitoring in Indiana streams, August 2004–September 2006........................44

2. Total mercury concentrations in environmental and field-duplicate samples 

from mercury monitoring in Indiana streams, August 2004–September 2006........................46

3. Methylmercury concentrations in environmental and field-duplicate samples 

from mercury monitoring in Indiana streams, August 2004–September 2006........................47

4. Matrix-spike and spike-duplicate sample quality-control data from mercury

monitoring in Indiana streams, August 2004–September 2006.................................................48

5. Total mercury and methylmercury concentrations in water samples 

from monitoring in Indiana streams, August 2004–September 2006, 

and streamflow conditions at the time of sample collection ....................................................50

6. Estimated particulate total mercury and particulate methylmercury 

concentrations and methylation efficiencies in water samples from monitoring 

in Indiana streams, August 2004–September 2006 .....................................................................59

7. Instantaneous streamflow and water-quality characteristics at monitoring

stations for mercury in Indiana streams, August 2004–September 2006................................68
44 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Appendix 1. Total mercury concentrations in quality-control field-blank samples from mercury monitoring in Indiana streams, 

August 2004–September 2006.—Continued

[Monitoring station number not assigned to field blanks; ng/L, nanograms per liter; NA, not analyzed; <, less than reporting limit listed]

Type of field blank Description of field blank Sample date

(month/day/year)

Mercury concentrations

Unfiltered total 

mercury

(ng/L)

Filtered total 

mercury1

(ng/L)

Equipment blank Sampling and processing equipment 08/23/2004 NA <0.04

Equipment blank Sampling and processing equipment 08/30/2004 NA <.02

Equipment blank Sampling and processing equipment 09/01/2004 NA <.03

Equipment blank Sampling and processing equipment 09/14/2004 NA <.04

Bottle blank Blank water, sample bottle, preservative 08/23/2004 <.04 NA

Bottle blank Blank water, sample bottle, preservative 09/14/2004 <.04 NA

Equipment blank Sampling and processing equipment 10/12/2004 NA <.01

Equipment blank Sampling and processing equipment 11/04/2004 NA <.04

Equipment blank Sampling and processing equipment 10/22/2004 NA <.04

Equipment blank Sampling and processing equipment 10/18/2004 NA <.04

Bottle blank Blank water, sample bottle, preservative 10/12/2004 <.04 NA

Bottle blank Blank water, sample bottle, preservative 11/04/2004 <.04 NA

Equipment blank Sampling and processing equipment 02/22/2005 NA <.04

Equipment blank Sampling and processing equipment 03/01/2005 NA <.04

Equipment blank Sampling and processing equipment 03/07/2005 NA <.04

Equipment blank Sampling and processing equipment 03/17/2005 NA <.04

Bottle blank Blank water, sample bottle, preservative 02/22/2005 <.04 NA

Bottle blank Blank water, sample bottle, preservative 03/17/2005 <.04 NA

Equipment blank Sampling and processing equipment 06/07/2005 NA .09

Equipment blank Sampling and processing equipment 06/14/2005 NA <.04

Equipment blank Sampling and processing equipment 06/23/2005 NA <.04

Equipment blank Sampling and processing equipment 06/30/2005 NA <.04

Bottle blank Blank water, sample bottle, preservative 06/07/2005 <.04 NA

Bottle blank Blank water, sample bottle, preservative 06/30/2005 <.04 NA

Equipment blank Sampling and processing equipment 08/29/2005 NA <.04

Equipment blank Sampling and processing equipment 09/08/2005 NA <.04

Equipment blank Sampling and processing equipment 09/14/2005 NA .01

Equipment blank Sampling and processing equipment 09/19/2005 NA .02
Appendixes 45

Appendix 1. Total mercury concentrations in quality-control field-blank samples from mercury monitoring in Indiana streams, 

August 2004–September 2006.—Continued

[Monitoring station number not assigned to field blanks; ng/L, nanograms per liter; NA, not analyzed; <, less than reporting limit listed]

Type of field blank Description of field blank Sample date

(month/day/year)

Mercury concentrations

Unfiltered total 

mercury

(ng/L)

Filtered total 

mercury1

(ng/L)

Bottle blank Blank water, sample bottle, preservative 08/29/2005 0.06 NA

Bottle blank Blank water, sample bottle, preservative 09/19/2005 <.04 NA

Equipment blank Sampling and processing equipment 11/28/2005 NA <.04

Equipment blank Sampling and processing equipment 12/06/2005 NA <.04

Equipment blank Sampling and processing equipment 12/19/2005 NA <.04

Equipment blank Sampling and processing equipment 12/16/2005 NA <.04

Bottle blank Blank water, sample bottle, preservative 11/28/2005 <.04 NA

Bottle blank Blank water, sample bottle, preservative 12/16/2005 <.04 NA

Equipment blank Sampling and processing equipment 02/27/2006 NA <.04

Equipment blank Sampling and processing equipment 03/07/2006 NA <.04

Equipment blank Sampling and processing equipment 03/13/2006 NA <.04

Equipment blank Sampling and processing equipment 03/17/2006 NA <.04

Bottle blank Blank water, sample bottle, preservative 02/27/2006 <.04 NA

Bottle blank Blank water, sample bottle, preservative 03/17/2006 <.04 NA

Equipment blank Sampling and processing equipment 05/08/2006 NA <.04

Equipment blank Sampling and processing equipment 05/12/2006 NA <.04

Equipment blank Sampling and processing equipment 05/18/2006 NA <.04

Equipment blank Sampling and processing equipment 05/25/2006 NA <.04

Bottle blank Blank water, sample bottle, preservative 05/08/2006 <.04 NA

Bottle blank Blank water, sample bottle, preservative 05/25/2006 .04 NA

Equipment blank Sampling and processing equipment 08/21/2006 NA <.04

Equipment blank Sampling and processing equipment 08/29/2006 NA <.04

Equipment blank Sampling and processing equipment 09/05/2006 NA .05

Equipment blank Sampling and processing equipment 09/08/2006 NA .05

Bottle blank Blank water, sample bottle, preservative 08/21/2006 <.04 NA

Bottle blank Blank water, sample bottle, preservative 09/08/2006 <.04 NA

1

Filtered concentration determined from water sample processed through a 0.7 micrometer nominal pore-size quartz-fiber filter.
46 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006

Appendix 2. Total mercury concentrations in environmental and field-duplicate samples from mercury monitoring in Indiana streams, 

August 2004–September 2006.

[Locations of stations shown on figure 1; station names shown in table 1; ng/L, nanograms per liter]

Unfiltered total mercury (ng/L) Filtered1 total mercury (ng/L)

Type of fieldduplicate 

sample

Monitoring 

station

 number

Sample 

date

(month/day/year)

Environmental sample

Fieldduplicate 

sample

Relative 

percent 

difference

Environmental sample

Fieldduplicate 

sample

Relative 

percent 

difference2

Split 19 08/27/2004 8.39 7.79 7.4 0.5 0.6 18.2

Split 16 08/31/2004 4.02 3.80 5.6 .56 .62 10.2

Split 14 09/01/2004 3.97 4.21 5.9 1.22 1.09 11.3

Split 6 10/13/2004 1.17 1.13 3.5 .32 .29 9.8

Split 13 10/18/2004 2.96 3.18 7.2 1.9 1.78 6.5

Split 10 10/22/2004 1.02 .94 8.2 .41 .38 7.6

Split 21 10/27/2004 1.3 1.08 18.5 .36 .30 18.2

Split 9 02/23/2005 1.1 1.39 23.3 .4 .51 24.2

Split 5 02/28/2005 4.52 4.26 5.9 1.86 1.82 2.2

Split 20 03/08/2005 4.05 4.60 12.7 2.09 2.54 19.4

Split 3 03/17/2005 1.21 1.08 11.4 .49 .52 5.9

Split 25 06/08/2005 2.54 2.41 5.3 .34 .34 0.0

Split 4 06/13/2005 2.78 2.38 15.5 .9 .65 32.3

Split 22 06/22/2005 1.43 1.23 15.0 .3 .33 9.5

Split 7 06/28/2005 6.47 7.28 11.8 .8 .61 27.0

Split 17 08/29/2005 1.19 1.26 5.7 .38 .34 11.1

Split 15 09/08/2005 7.02 6.77 3.6 .96 .85 12.2

Split 2 09/13/2005 .67 .79 16.4 .33 .43 26.3

Split 1 09/15/2005 .86 .95 9.9 .59 .53 10.7

Concurrent 14 11/30/2005 1.3 10.8 4.7 4.4 3.51 22.5

Concurrent 24 12/08/2005 .75 .68 9.8 .35 .36 2.8

Concurrent 4 12/12/2005 .34 .38 11.1 .26 .31 17.5

Concurrent 8 12/16/2005 .88 .90 2.2 .06 .08 28.6

Concurrent 9 03/08/2006 1.34 1.20 11.0 .57 .72 23.3

Concurrent 1 03/10/2006 21.2 22.0 3.7 4.17 4.18 .2

Concurrent 18 03/13/2006 15.0 15.0 0.0 5.85 4.88 18.1

Concurrent 23 03/16/2006 6.89 6.66 3.4 3.17 3.38 6.4

Concurrent 12 05/11/2006 17.9 18.1 1.1 2.2 2.24 1.8

Concurrent 11 05/12/2006 7.59 7.64 .7 4.8 4.57 4.9

Concurrent 7 05/16/2006 17.8 16.2 9.4 1.53 1.40 8.9

Concurrent 19 05/23/2006 23.6 21.2 10.7 1.89 1.91 1.1

Concurrent 5 08/21/2006 2.14 2.4 11.5 .37 .37 0.0

Concurrent 13 08/24/2006 2.03 1.97 3.0 .48 .49 2.1

Concurrent 21 08/30/2006 3.27 2.69 19.5 .48 .46 4.3

Concurrent 2 09/07/2006 .94 1.16 21.0 .54 .52 3.8

1

Filtered concentration determined from water sample processed through a 0.7 micrometer nominal pore-size quartz-fiber filter.

2

Relative percent difference is the nonnegative difference of the duplicate and environmental sample concentrations divided by the average of the concentrations, expressed as a percentage. 
Appendixes 47

Appendix 3. Methylmercury concentrations in environmental and field-duplicate samples from mercury monitoring in Indiana streams, 

August 2004–September 2006.

[Locations of stations shown on figure 1; station names shown in table 1; ng/L, nanograms per liter; <, less than; —, not computed]

Unfiltered methylmercury (ng/L) Filtered1 methylmercury (ng/L)

Type of fieldduplicate 

sample

Monitoring 

station

 number

Sample 

date

(month/day/year)

Environmental sample

Fieldduplicate 

sample

Relative 

percent 

difference2

Environmental sample

Fieldduplicate 

sample

Relative 

percent 

difference2

Split 19 08/27/2004 0.22 0.23 4.4 0.05 0.06 18.2

Split 16 08/31/2004 .18 .16 11.8 .08 .07 13.3

Split 14 09/01/2004 .05 .05 .0 <.04 .04 —

Split 6 10/13/2004 .12 .10 18.2 <.04 <.04 —

Split 13 10/18/2004 .1 .09 1.5 <.04 <.04 —

Split 10 10/22/2004 <.04 <.04 — <.04 <.04 —

Split 21 10/27/2004 <.04 .05 — <.04 <.04 —

Split 9 02/23/2005 <.04 .06 — <.04 <.04 —

Split 5 02/28/2005 .06 .08 28.6 <.04 .05 —

Split 20 03/08/2005 .09 .11 20.0 .05 .06 18.2

Split 3 03/17/2005 .06 .07 15.4 <.04 <.04 —

Split 25 06/08/2005 .42 .35 18.2 .08 .08 0.0

Split 4 06/13/2005 .33 .32 3.1 .13 .16 20.7

Split 22 06/22/2005 .08 .07 13.3 .05 .05 0.0

Split 7 06/28/2005 .07 .06 15.4 .07 .06 15.4

Split 17 08/29/2005 .12 .10 18.2 <.04 .06 —

Split 15 09/08/2005 .2 .17 16.2 .07 .06 15.4

Split 2 09/13/2005 .12 .12 0.0 .06 .08 28.6

Split 1 09/15/2005 .1 .08 22.2 .05 .05 0.0

Concurrent 14 11/30/2005 .19 .15 23.5 .06 .06 0.0

Concurrent 24 12/08/2005 <.04 <.04 — <.04 <.04 —

Concurrent 4 12/12/2005 <.04 <.04 — <.04 <.04 —

Concurrent 8 12/16/2005 .09 .08 11.8 .06 <.04 —

Concurrent 9 03/08/2006 <.04 <.04 — <.04 <.04 —

Concurrent 1 03/10/2006 .29 .29 0.0 .05 .06 18.2

Concurrent 18 03/13/2006 .14 .13 7.4 .05 .05 .0

Concurrent 23 03/16/2006 .05 .06 18.2 .08 .06 28.6

Concurrent 12 05/11/2006 .44 .46 4.4 .08 .08 .0

Concurrent 11 05/12/2006 .2 .19 5.1 .13 .11 16.7

Concurrent 7 05/16/2006 .26 .24 8.0 .04 <.04 —

Concurrent 19 05/23/2006 .23 .23 .0 .06 .07 15.4

Concurrent 5 08/21/2006 .16 .14 13.3 <.04 <.04 —

Concurrent 13 08/24/2006 .08 .06 28.6 <.04 <.04 —

Concurrent 21 08/30/2006 .07 .06 15.4 .06 .05 18.2

Concurrent 2 09/07/2006 .06 .07 15.4 .06 .06 .0

1

Filtered concentration determined from water sample processed through a 0.7 micrometer nominal pore-size quartz-fiber filter.

2

Relative percent difference is the nonnegative difference of the duplicate and environmental sample concentrations divided by the average of the concentrations, expressed as a percentage. 
48 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 4. Matrix-spike and spike-duplicate sample quality-control data from mercury monitoring in Indiana streams, August 2004–September 2006.—Continued [UTHG, unfiltered total mercury; FTHG, filtered total mercury; UMHG, unfiltered methylmercury; R, field-duplicate sample] Monitoring station number Sample type Analysis Sample date (month/day/year) Percent recovery1 Relative percent difference2 Monitoring station number Sample type Analysis Sample date (month/day/year) Percent recovery1 Relative percent difference2

1 Spike UTHG 08/23/2004 101 13 Spike UTHG 09/09/2005 96

12 Spike UTHG 08/25/2004 100 15 Spike UTHG 11/30/2005 10113 Spike UTHG 09/09/2004 91 23 Spike UTHG 12/08/2005 10325 Spike UTHG 10/07/2004 100 9 Spike UTHG 03/08/2006 10325 Spike UTHG 10/07/2004 93 9R Spike UTHG 03/08/2006 98

6 Spike UTHG 10/13/2004 102 1 Spike UTHG 03/10/2006 96

12 Spike UTHG 10/15/2004 99 22 Spike UTHG 03/15/2006 9613 Spike UTHG 10/18/2004 97 23 Spike UTHG 03/16/2006 9822 Spike UTHG 10/20/2004 99 15 Spike UTHG 05/10/2006 9817 Spike UTHG 10/25/2004 101 13 Spike UTHG 05/11/2006 9712 Spike UTHG 02/24/2005 104 3 Spike UTHG 05/25/2006 96

5 Spike UTHG 02/28/2005 1015R Spike UTHG 02/28/2005 99

14 Spike UTHG 03/02/2005 103 6 Spike UMHG 08/31/2004 8220 Spike UTHG 03/08/2005 104 6 Duplicate UMHG 08/31/2004 97 16.823 Spike UTHG 03/10/2005 111 3 Spike UMHG 10/19/2004 9623 Duplicate UTHG 03/10/2005 112 9.0 20 Spike UMHG 10/26/2004 11424 Spike UTHG 03/10/2005 102 3 Duplicate UMHG 10/19/2004 103 7.0

4 Spike UTHG 03/17/2005 95 20 Duplicate UMHG 10/26/2004 110 3.6

25R Spike UTHG 06/08/2005 91 21R Spike UMHG 10/27/2004 112

8 Spike UTHG 06/27/2005 95 21R Duplicate UMHG 10/27/2004 95 16.4
Appendixes 49

Appendix 4. Matrix-spike and spike-duplicate sample quality-control data from mercury monitoring in Indiana streams, August 2004–September 2006.—Continued[UTHG, unfiltered total mercury; FTHG, filtered total mercury; UMHG, unfiltered methylmercury; R, field-duplicate sample]

Monitoring 

station 

number

Sample 

type Analysis

Sample 

date

(month/day/year)

Percent 

recovery1

Relative 

percent 

difference2

Monitoring 

station 

number

Sample type Analysis Sample date (month/day/year) Percent recovery1 Relative percent difference2

11 Spike UTHG 06/29/2005 82 13 Spike UMHG 06/10/2005 9911 Duplicate UTHG 06/29/2005 97 6.8 19 Spike UMHG 06/21/2005 97

12 Spike UTHG 06/29/2005 91 13 Duplicate UMHG 06/10/2005 109 9.617 Spike UTHG 08/29/2005 81 19 Duplicate UMHG 06/21/2005 97 .017 Duplicate UTHG 08/29/2005 103 23.3 10 Spike UMHG 06/30/2005 110

5 Spike UTHG 09/06/2005 100 10 Duplicate UMHG 06/30/2005 105 4.7

25 Spike UTHG 09/07/2005 100 6 Spike UMHG 08/31/2004 82

3 Spike FTHG 05/25/2006 104 6 Spike FTHG 03/03/2006 102

17 Spike FTHG 05/22/2006 103 13 Spike FTHG 12/01/2005 97

11 Spike FTHG 05/12/2006 106 13 duplicate FTHG 12/01/2005 101 4.5

12 Spike FTHG 05/11/2006 106 16 Spike FTHG 11/29/2005 91

25 Spike FTHG 05/09/2006 102 10 Spike FTHG 09/16/2005 9623 Spike FTHG 03/16/2006 97 7 Spike FTHG 09/14/2005 10218R Spike FTHG 03/13/2006 100 13 Spike FTHG 09/09/2005 88

8 Spike FTHG 03/10/2006 92 6 Spike FTHG 09/02/2005 927 Spike FTHG 03/08/2006 97 23 Spike FTHG 09/01/2005 98

1 Percent recovery was computed as the mercury concentration in the matrix-spike sample divided by the sum of the mercury concentration in the sample and the mercury concentration in the spike solution, 

expressed as a percentage.

2 Relative percent difference is the nonnegative difference of the duplicate and environmental sample concentrations divided by the average of the concentrations, expressed as a percentage.
50 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] Monitoring station number Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category

1 Fall Creek near Fortville 08/23/2004 1.28 0.23 0.07 <0.04 Stable low Medium.

10/12/2004 .58 .44 <.04 <.04 Stable low Low.02/22/2005 1.16 .35 <.04 <.04 Falling High.06/27/2005 2.35 .43 .11 .06 Stable low Medium.09/15/2005 .86 .59 .10 .05 Falling Low.12/16/2005 .39 .22 .04 <.04 Rising Medium.03/10/2006 21.2 4.17 .29 .05 Rising Event.05/15/2006 6.00 2.11 .14 <.04 Falling Event.09/05/2006 1.66 .26 .07 <.04 Stable low Low.

2 Eel River near Logansport 08/30/2004 14.7 3.99 .27 .09 Falling Event.

10/19/2004 .79 .55 <.04 <.04 Stable normal Medium.03/17/2005 .88 .49 .04 .04 Stable low High.06/14/2005 2.21 .94 .25 .11 Rising High.09/13/2005 .67 .33 .12 .06 Stable low Low.12/13/2005 .28 .18 <.04 <.04 Stable low Medium.03/07/2006 .74 .39 .04 <.04 Stable normal Medium.05/17/2006 7.92 3.02 .17 .06 Falling Event.09/07/2006 .94 .54 .06 .06 Stable low Medium.

 3 Tippecanoe River at Winamac 09/02/2004 3.81 1.35 .16 .08 Falling Event.

10/19/2004 .61 .34 <.04 <.04 Stable low Medium.03/17/2005 1.21 .49 .06 <.04 Falling High.06/14/2005 2.63 .42 .19 .05 Rising Medium.09/13/2005 .83 .28 .05 <.04 Stable low Low.12/13/2005 .66 .23 <.04 <.04 Stable low Medium.03/07/2006 .59 .27 <.04 <.04 Stable normal Medium.05/25/2006 3.66 .68 .13 .04 Falling High.08/31/2006 7.42 1.23 .13 .04 Falling High.
Appendixes 51

Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] 

Monitoring 

station 

number

Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category

 4 Wildcat Creek near Lafayette 08/30/2004 8.33 1.11 0.21 0.05 Rising High.

10/21/2004 1.55 1.02 .05 <.04 Stable normal Medium.03/16/2005 .57 .44 <.04 <.04 Falling Medium.06/13/2005 2.78 .90 .33 .13 Rising Medium.09/12/2005 .68 .28 .10 .06 Stable low Low.12/12/2005 .34 .26 <.04 <.04 Falling Medium.03/06/2006 .66 .33 <.04 <.04 Stable normal Medium.05/17/2006 7.35 1.04 .14 <.04 Falling Event.09/07/2006 1.39 .48 .08 .04 Stable low Medium.

 5 Wabash River at U.S. Highway 40 at Terre Haute 09/10/2004 5.13 1.06 .19 .05 Stable normal Medium.

11/03/2004 11.6 .86 .26 .05 Rising High.

02/28/2005 4.52 1.86 .06 <.04 Falling High.06/07/2005 2.38 .52 .42 .05 Rising Medium.09/06/2005 2.54 .3 .11 .05 Rising Low.

11/28/2005 3.22 .78 .08 <.04 Falling Medium.

02/27/2006 4.32 1.24 .06 <.04 Falling Medium.05/08/2006 4.99 .56 .12 <.04 Falling High.08/21/2006 2.14 .37 .16 <.04 Falling Low.

 6 Mill Creek at tailwater pool near Manhattan 08/31/2004 1.36 .37 .32 .06 Stable low Low.

10/13/2004 1.17 .32 .12 <.04 Stable low Medium.03/04/2005 3.26 2.45 <.04 <.04 Falling Medium.06/06/2005 2.18 .96 .14 .06 Stable normal Medium.09/02/2005 2.32E 2.17E .57 .42 Stable high High.12/02/2005 1.39 .74 <.04 <.04 Stable normal High.03/03/2006 1.67 .9 <.04 <.04 Stable normal Medium.05/08/2006 1.94 .94 .06 <.04 Stable normal High.08/21/2006 1.56 .31 .23 .05 Stable low Low.
52 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] Monitoring station number Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category 7 White River near Centerton 08/24/2004 9.10 0.64 0.29 0.12 Stable low Medium. 10/14/2004 10.1 1.47 .24 .12 Stable low Medium. 02/23/2005 6.34 .92 .09 .08 Falling High. 06/28/2005 6.47 .8 .07 .07 Stable low Medium. 09/14/2005 5.66 .77 .25 .1 Stable low Low. 12/14/2005 3.29 .54 .08 <.04 Falling Medium. 03/08/2006 2.90 .85 .07 <.04 Rising Medium. 05/16/2006 17.8 1.53 .26 .04 Falling Event. 09/06/2006 5.56 .61 .12 .05 Falling Low. 8 White River near Nora 08/23/2004 2.55 .44 .11 .07 Stable low Medium. 10/12/2004 1.36 .53 .07 .06 Stable low Low. 02/22/2005 2.64 .75 <.04 <.04 Falling High. 06/27/2005 2.54 .55 .12 .07 Stable low Medium. 09/15/2005 2.07 .49 .11 .06 Stable low Medium. 12/16/2005 .88 .06 .09 .06 Stable normal Medium. 03/10/2006 11.3 1.44 .09 <.04 Rising High. 05/15/2006 9.51 2.35 .26 .05 Falling Event. 09/05/2006 3.08 .41 .09 .07 Stable low Low.

 9 Sugar Creek at New Palestine 08/24/2004 .76 .31 <.04 <.04 Stable low Low.

10/14/2004 1.36 .99 .04 .04 Stable low Low.02/23/2005 1.10 .40 <.04 <.04 Falling High.06/28/2005 1.31 .58 .1 .06 Stable low Medium.09/14/2005 .75 .41 .07 .06 Stable low Low.12/14/2005 .43 .18 <.04 <.04 Stable low Medium.03/08/2006 1.34 .57 <.04 <.04 Rising Medium.05/16/2006 4.76 1.95 .12 .04 Falling Event.09/06/2006 .70 .34 .05 <.04 Falling Low.
Appendixes 53

Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] 

Monitoring 

station 

number

Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category

10 East Fork Whitewater River at Brookville 09/03/2004 0.54 0.40 <0.04 <0.04 Stable low Low.

10/22/2004 1.02 .41 <.04 <.04 Stable low High.02/25/2005 1.85 1.21 <.04 <.04 Stable normal High.06/30/2005 .34 .23 <.04 <.04 Rising High.09/16/2005 .32 .22 <.04 <.04 Stable low Medium.12/19/2005 .24 .17 <.04 <.04 Stable normal High.03/17/2006 1.21 .65 <.04 <.04 Rising Event.05/18/2006 .64 .44 <.04 <.04 Falling Event.09/08/2006 .26 .22 .04 <.04 Stable low Medium.

11 Vernon Fork Muscatatuck River at Vernon 08/25/2004 2.80 1.11 .11 .07 Stable low Medium.

10/15/2004 1.08 .90 <.04 <.04 Stable low High.02/24/2005 1.50 1.25 .08 .05 Falling High.06/29/2005 2.32 1.21 .13 .09 Rising Low.09/19/2005 4.50E 1.07E .07 .07 Stable low Low.12/15/2005 1.82 .92 .06 .06 Rising Medium.03/09/2006 16.2 6.14 .19 .06 Rising Event.05/12/2006 7.59 4.80 .20 .13 Falling High.08/24/2006 1.34 .96 .08 .09 Stable low Low.

12 White River at State Road 258 near Seymour 08/25/2004 1.23 .16 .12 .06 Stable normal Low.

10/15/2004 .96 .34 .05 <.04 Stable low Low.02/24/2005 1.82 .52 .05 <.04 Falling High.06/29/2005 1.67 .35 .12 .04 Falling Medium.09/19/2005 3.67E 1.35E .10 .04 Falling Low.12/15/2005 .73 .23 .05 <.04 Rising Medium.03/09/2006 20.1 4.45 .25 .06 Rising High.

05/11/2006 17.9 2.20 .44 .08 Rising High.

08/24/2006 1.36 .29 .06 <.04 Stable low Medium.
54 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] Monitoring station number Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category 13 Blue River at Fredericksburg 09/09/2004 1.74 0.89 0.09 0.09 Stable low Medium. 10/18/2004 2.96 1.90 .10 <.04 Stable low Medium. 03/03/2005 .83 .43 <.04 <.04 Falling High. 06/10/2005 1.85 .67 .20 .13 Stable low Medium. 09/09/2005 1.98 .64 .08 .05 Falling Low. 12/01/2005 2.61 1.62 .05 <.04 Falling High. 03/02/2006 .93 .48 <.04 <.04 Stable low Medium. 05/11/2006 2.42 .68 .13 .04 Rising High. 08/24/2006 2.03 .48 .08 <.04 Stable low Medium. 14 Patoka River at Winslow 09/01/2004 3.97 1.22 .05 <.04 Stable low Medium. 10/28/2004 16.0 4.30 .06 .06 Falling High. 03/02/2005 2.63 .63 .08 <.04 Falling High. 06/09/2005 2.70 .30 .13 <.04 Stable low Low. 09/08/2005 2.79 .95 .07 .06 Stable low Low. 11/30/2005 10.3 4.40 .19 .06 Falling High. 03/01/2006 1.78 .52 .07 <.04 Falling Medium. 05/10/2006 8.74 .78 .32 .14 Falling High. 08/23/2006 4.60 1.10 .07 <.04 Falling Medium.

15 White River at Petersburg 10/07/2004 4.05 .79 .40 .1 Stable low Low.

10/28/2004 12.0 2.58 .20 .07 Falling Medium.03/02/2005 3.60 .80 .06 <.04 Falling High.06/09/2005 6.15 1.48 .28 <.04 Falling Medium.09/08/2005 7.02 .96 .20 .07 Falling Medium.

11/30/2005 5.63 .97 .09 <.04 Rising Medium.

03/01/2006 3.42 .46 .06 <.04 Falling Medium.05/10/2006 6.41 .65 .17 <.04 Stable normal High.08/23/2006 4.40 .61 .41 .05 Falling Low.
Appendixes 55

Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] 

Monitoring 

station 

number

Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category

16 Busseron Creek near Carlisle 08/31/2004 4.02 0.56 0.18 0.08 ND ND.

10/29/2004 3.81 1.73 .17 .13 ND ND.03/01/2005 1.37 .35 .05 .05 ND ND.06/08/2005 2.47 2.44 .12 .07 ND ND.09/07/2005 3.42E .10E .12 <.04 ND ND.

11/29/2005 6.24 2.19 .12 .05 ND ND.

02/28/2006 1.38 .32 .08 <.04 ND ND.05/09/2006 1.55 .49 .10 .05 ND ND.08/22/2006 2.49 .42 .13 <.04 ND ND.

17 Mississinewa River at County Road 275 East near Peoria 08/26/2004 2.38 .99 .16 <.04 Stable low Medium.

10/25/2004 2.31 .32 .05 <.04 Stable low Medium.03/07/2005 1.74 1.01 .05 .04 Stable normal High.06/20/2005 1.12 .68 .18 .1 Stable normal Medium.08/29/2005 1.19 .38 .12 <.04 Stable low Low.12/05/2005 3.25 2.16 .05 <.04 Stable normal High.03/13/2006 3.39 1.76 .06 .05 Stable normal High.05/22/2006 3.33 2.09 .06 <.04 Stable low High.08/28/2006 1.38 .69 .09 <.04 Rising Medium.

18 Wabash River at County Road 200 West near Huntington 08/26/2004 1.48 .40 .13 .05 Stable low Medium.

10/25/2004 1.24 .35 .08 <.04 Stable low Medium.03/07/2005 7.66 3.62 .13 <.04 Rising High.06/20/2005 2.59 1.68 .40 .17 Stable normal Medium.08/29/2005 2.67 .46 .04 <.04 Stable low Medium.12/05/2005 7.14 3.79 .05 <.04 Falling Medium.03/13/2006 15.0 5.85 .14 .05 Stable high Event.05/22/2006 4.37 2.46 .12 <.04 Stable normal High.08/28/2006 2.10 .47 .05 <.04 Stable normal Event.
56 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] Monitoring station number Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category 19 Maumee River at New Haven 08/27/2004 8.39 0.50 0.22 0.05 Stable low Medium. 10/26/2004 4.72 .80 .19 .06 Stable low Medium. 03/08/2005 9.64 3.81 .07 .06 Stable normal High. 06/21/2005 3.45 .46 .24 .09 Stable low Low. 08/30/2005 9.28 .50 .43 .07 Stable low Low. 12/06/2005 7.85 5.14 .07 <.04 Falling High. 03/14/2006 26.9 5.97 .32 <.04 Rising Event. 05/23/2006 23.6 1.89 .23 .06 Rising High. 08/29/2006 12.5 1.00 .27 .05 Falling High. 20 Fish Creek near Artic 09/07/2004 2.48 1.13 .16 .07 Stable low Medium. 10/26/2004 1.00 .62 .08 .07 Stable low Medium. 03/08/2005 4.05 2.09 .09 .05 Rising Event. 06/21/2005 1.46 .63 .15 .10 Stable low Low. 08/30/2005 .98 .43 .08 <.04 Stable low Low. 12/06/2005 .76 .51 .06 <.04 Stable normal High. 03/14/2006 8.66 4.79 .09 .06 Rising Event. 05/23/2006 2.20 .77 .18 .06 Falling High. 08/29/2006 8.62 2.29 .21 <.04 Peak High.

21 St. Joseph River at Elkhart 09/07/2004 1.80 .74 .10 .10 Stable normal Medium.

10/27/2004 1.30 .36 <.04 <.04 Stable low Medium.03/09/2005 1.74 .59 .08 .05 Stable high Event.06/22/2005 1.77 .38 .08 .06 Stable normal Medium.08/31/2005 .96 .30 .12 .12E Stable low Medium.12/07/2005 .39 .25 <.04 <.04 Stable low Low.03/15/2006 9.05 2.28 .10 <.04 Falling Event.05/24/2006 2.34 .62 .08 .04 Falling High.08/30/2006 3.27 .48 .07 .06 Stable normal Medium.
Appendixes 57

Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] 

Monitoring 

station 

number

Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category

22 Trail Creek at Michigan City Harbor 09/08/2004 1.16 0.48 0.06 0.05 Stable normal Medium.

10/20/2004 .55 .17 <.04 <.04 Stable low Medium.03/09/2005 1.42 .83 .09 .08 Stable normal High.06/22/2005 1.43 .30 .08 .05 Stable normal Medium.08/31/2005 .79 .25 <.04 <.04 Stable normal Medium.12/07/2005 .82 .33 <.04 <.04 Stable low Medium.03/15/2006 5.94 2.14 .08 .05 Stable normal Event.05/24/2006 1.86 .40 .09 .04 Stable normal Medium.08/30/2006 7.15 3.31 .39 .23 Rising Event.

23 Deep River at Lake George outlet at Hobart 09/08/2004 2.16 .88 <.04 <.04 Stable normal Medium.

10/20/2004 1.85 .59 <.04 <.04 Stable normal Medium.03/10/2005 1.37 .80 .08 <.04 Falling High.06/23/2005 1.43 .62 .09 <.04 Stable low Low.09/01/2005 1.43 .64 .05 <.04 Falling Low.12/08/2005 1.88 .85 .05 <.04 Stable low Medium.03/16/2006 6.89 3.17 .05 .08 Falling Event.05/25/2006 1.38 .55 .05 <.04 Rising High.08/31/2006 3.02 1.52 .15 .11 Falling Event.

24 Kankakee River at Shelby 09/08/2004 7.33 1.05 .13 .06 Stable normal High.

10/21/2004 .80 .19 <.04 <.04 Stable normal Medium.03/10/2005 2.40 .99 .10 .06 Falling Event.06/23/2005 5.28 .31 .04 .04 Falling Low.09/01/2005 1.82E .16E .05 .05E Falling Low.12/08/2005 .75 .35 <.04 <.04 Stable normal Medium.03/16/2006 12.2 3.49 .11 .04 Rising Event.05/25/2006 3.73 .46 .07 <.04 Falling High.08/31/2006 3.23 .52 .07 <.04 Peak High.
58 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 5. Total mercury and methylmercury concentrations in water samples from monitoring in Indiana streams, August 2004–September 2006, and streamflow conditions at the time of sample collection.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; <, less than; E, estimated; ND, not determined] Monitoring station number Station name Sample date (month/day/year) Unfiltered total mercury (ng/L) Filtered total mercury1 (ng/L) Unfiltered methylmercury (ng/L) Filtered methylmercury1 (ng/L) Streamflow hydrograph condition Streamflow statistical category 25 Wabash River at Vigo Street at Vincennes 10/07/2004 1.95 0.16 0.22 <0.04 Stable low Low. 11/04/2004 9.73 1.69 .16 .08 Falling High 03/01/2005 4.12 2.00 .09 <.04 Falling Event. 06/08/2005 2.54 .34 .42 .08 Stable low Medium. 09/07/2005 2.44 .29 .27 .07 Stable low Low. 11/29/2005 4.11 .92 .09 <.04 Stable normal Medium. 02/28/2006 5.64 1.24 .09 <.04 Falling Medium. 05/09/2006 6.45 .53 .15 <.04 Falling High. 08/22/2006 3.86 .38 .21 .04 Stable low Low.

1Filtered concentration determined from water sample processed with 0.7 micrometer nominal pore-size quartz-fiber filter.
Appendixes 59

Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] 

Total mercury Methylmercury

Monitoring

station 

number

Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3

 1 Fall Creek near Fortville 08/23/2004 1.05 82.0 0.07 100 5.5

10/12/2004 .14 24.1 ND ND ND02/22/2005 .81 69.8 ND ND ND06/27/2005 1.92 81.7 .05 45 4.709/15/2005 .27 31.4 .05 50 11.612/16/2005 .17 43.6 .04 100 10.303/10/2006 17.03 80.3 .24 83 1.405/15/2006 3.89 64.8 .14 100 2.309/05/2006 1.40 84.3 .07 100 4.2

 2 Eel River near Logansport 08/30/2004 10.71 72.9 .18 67 1.8

10/19/2004 .24 30.4 ND ND ND03/17/2005 .39 44.3 .00 0 4.506/14/2005 1.27 57.5 .14 56 11.309/13/2005 0.34 50.7 .06 50 17.912/13/2005 .10 35.7 ND ND ND03/07/2006 .35 47.3 .04 100 5.405/17/2006 4.90 61.9 .11 65 2.109/07/2006 .40 42.6 .00 0 6.4

 3 Tippecanoe River at Winamac 09/02/2004 2.46 64.6 .08 50 4.2

10/19/2004 .27 44.3 ND ND ND03/17/2005 .72 59.5 .06 100 5.006/14/2005 2.21 84.0 .14 74 7.209/13/2005 .55 66.3 .05 100 6.012/13/2005 .43 65.2 ND ND ND03/07/2006 .32 54.2 ND ND ND05/25/2006 2.98 81.4 .09 69 3.608/31/2006 6.19 83.4 .09 69 1.8
60 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] Total mercury Methylmercury Monitoring station number Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3 4 Wildcat Creek near Lafayette 08/30/2004 7.22 86.7 0.16 76 2.5 10/21/2004 .53 34.2 .05 100 3.2 03/16/2005 .13 22.8 ND ND ND 06/13/2005 1.88 67.6 .20 61 11.9 09/12/2005 .40 58.8 .04 40 14.7 12/12/2005 .08 23.5 ND ND ND 03/06/2006 .33 50.0 ND ND ND 05/17/2006 6.31 85.9 .14 100 1.9 09/07/2006 .91 65.5 .04 50 5.8 5 Wabash River at U.S. Highway 40 at Terre Haute 09/10/2004 4.07 79.3 .14 74 3.7 11/03/2004 10.74 92.6 .21 81 2.2 02/28/2005 2.66 58.8 .06 100 1.3 06/07/2005 1.86 78.2 .37 88 17.6 09/06/2005 2.24 88.2 .06 55 4.3 11/28/2005 2.44 75.8 .08 100 2.5 02/27/2006 3.08 71.3 .06 100 1.4

05/08/2006 4.43 88.8 .12 100 2.408/21/2006 1.77 82.7 .16 100 7.5

 6 Mill Creek at tailwater pool near Manhattan 08/31/2004 .99 72.8 .26 81 23.5

10/13/2004 .85 72.6 .12 100 10.303/04/2005 .81 24.8 ND ND ND06/06/2005 1.22 56.0 .08 57 6.409/02/2005 .15 6.5 .15 26 24.612/02/2005 .65 46.8 ND ND ND03/03/2006 .77 46.1 ND ND ND05/08/2006 1.00 51.5 .06 100 3.108/21/2006 1.25 80.1 .18 78 14.7
Appendixes 61

Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] 

Total mercury Methylmercury

Monitoring

station 

number

Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3

 7 White River near Centerton 08/24/2004 8.46 93.0 0.17 59 3.2

10/14/2004 8.63 85.4 .12 50 2.402/23/2005 5.42 85.5 .01 11 1.406/28/2005 5.67 87.6 .00 0 1.109/14/2005 4.89 86.4 .15 60 4.412/14/2005 2.75 83.6 .08 100 2.403/08/2006 2.05 70.7 .07 100 2.405/16/2006 16.27 91.4 .22 85 1.509/06/2006 4.95 89.0 .07 58 2.2

 8 White River near Nora 08/23/2004 2.11 82.7 .04 36 4.3

10/12/2004 .83 61.0 .01 14 5.102/22/2005 1.89 71.6 ND ND ND06/27/2005 1.99 78.3 .05 42 4.709/15/2005 1.58 76.3 .05 45 5.312/16/2005 .82 93.2 .03 33 10.203/10/2006 9.86 87.3 .09 100 .805/15/2006 7.16 75.3 .21 81 2.709/05/2006 2.67 86.7 .02 22 2.9

 9 Sugar Creek at New Palestine 08/24/2004 .45 59.2 ND ND ND

10/14/2004 .37 27.2 0.0 0 2.902/23/2005 .70 63.6 ND ND ND06/28/2005 .73 55.7 .04 40 7.609/14/2005 .34 45.3 .01 14 9.312/14/2005 .25 58.1 ND ND ND03/08/2006 .77 57.5 ND ND ND05/16/2006 2.81 59.0 .08 67 2.509/06/2006 .36 51.4 .05 100 7.1
62 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] Total mercury Methylmercury Monitoring station number Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3 10 East Fork Whitewater River at Brookville 09/03/2004 0.14 25.9 ND ND ND 10/22/2004 .61 59.8 ND ND ND 02/25/2005 .64 34.6 ND ND ND 06/30/2005 .11 32.4 ND ND ND 09/16/2005 .10 31.3 ND ND ND 12/19/2005 .07 29.2 ND ND ND 03/17/2006 .56 46.3 ND ND ND 05/18/2006 .20 31.3 ND ND ND 09/08/2006 .04 15.4 0.04 100 15.4 11 Vernon Fork Muscatatuck River at Vernon 08/25/2004 1.69 60.4 .04 36 3.9 10/15/2004 .18 16.7 ND ND ND 02/24/2005 .25 16.7 .03 38 5.3 06/29/2005 1.11 47.8 .04 31 5.6 09/19/2005 3.43 76.2 .00 0 1.6 12/15/2005 .90 49.5 .00 0 3.3 03/09/2006 10.06 62.1 .13 68 1.2

05/12/2006 2.79 36.8 .07 35 2.608/24/2006 .38 28.4 ND ND 6.0

12 White River at State Road 258 near Seymour 08/25/2004 1.07 87.0 .06 50 9.8

10/15/2004 .62 64.6 .05 100 5.202/24/2005 1.30 71.4 .05 100 2.706/29/2005 1.32 79.0 .08 67 7.209/19/2005 2.32 63.2 .06 60 2.712/15/2005 .50 68.5 .05 100 6.803/09/2006 15.65 77.9 .19 76 1.2

05/11/2006 15.70 87.7 .36 82 2.5

08/24/2006 1.07 78.7 .06 100 4.4
Appendixes 63

Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] 

Total mercury Methylmercury

Monitoring

station 

number

Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3

13 Blue River at Fredericksburg 09/09/2004 0.85 48.9 0.00 0 5.2

10/18/2004 1.06 35.8 .10 100 3.403/03/2005 .40 48.2 ND ND ND06/10/2005 1.18 63.8 .07 35 10.809/09/2005 1.34 67.7 .03 38 4.012/01/2005 .99 37.9 .05 100 1.903/02/2006 .45 48.4 ND ND ND

05/11/2006 1.74 71.9 .09 69 5.4

08/24/2006 1.55 76.4 .08 100 3.9

14 Patoka River at Winslow 09/01/2004 2.75 69.3 .05 100 1.3

10/28/2004 11.70 73.1 .00 0 .403/02/2005 2.00 76.0 .08 100 3.006/09/2005 2.40 88.9 .13 100 4.809/08/2005 1.84 65.9 .01 14 2.5

11/30/2005 5.90 57.3 .13 68 1.8

03/01/2006 1.26 70.8 .07 100 3.905/10/2006 7.96 91.1 .18 56 3.708/23/2006 3.50 76.1 .07 100 1.5

15 White River at Petersburg 10/07/2004 3.26 80.5 .30 75 9.9

10/28/2004 9.42 78.5 .13 65 1.703/02/2005 2.80 77.8 .06 100 1.706/09/2005 4.67 75.9 .28 100 4.609/08/2005 6.06 86.3 .13 65 2.8

11/30/2005 4.66 82.8 .09 100 1.6

03/01/2006 2.96 86.5 .06 100 1.805/10/2006 5.76 89.9 .17 100 2.708/23/2006 3.79 86.1 .36 88 9.3
64 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] Total mercury Methylmercury Monitoring station number Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3 16 Busseron Creek near Carlisle 08/31/2004 3.46 86.1 0.10 56 4.5 10/29/2004 2.08 54.6 .04 24 4.5 03/01/2005 1.02 74.5 .00 0 3.6 06/08/2005 .03 1.2 .05 42 4.9 09/07/2005 3.32 97.1 .12 100 3.5 11/29/2005 4.05 64.9 .07 58 1.9 02/28/2006 1.06 76.8 .08 100 5.8 05/09/2006 1.06 68.4 .05 50 6.5 08/22/2006 2.07 83.1 .13 100 5.2 17 Mississinewa River at County Road 275 East near Peoria 08/26/2004 1.39 58.4 .16 100 6.7 10/25/2004 1.99 86.1 .05 100 2.2 03/07/2005 .73 42.0 .01 20 2.9 06/20/2005 .44 39.3 .08 44 16.1 08/29/2005 .81 68.1 .12 100 10.1 12/05/2005 1.09 33.5 .05 100 1.5 03/13/2006 1.63 48.1 .01 17 1.8

05/22/2006 1.24 37.2 .06 100 1.808/28/2006 .69 50.0 .09 100 6.5

18 Wabash River at County Road 200 West near Huntington 08/26/2004 1.08 73.0 .08 62 8.8

10/25/2004 .89 71.8 .08 100 6.503/07/2005 4.04 52.7 .13 100 1.706/20/2005 .91 35.1 .23 58 15.408/29/2005 2.21 82.8 .04 100 1.512/05/2005 3.35 46.9 .05 100 .703/13/2006 9.15 61.0 .09 64 .905/22/2006 1.91 43.7 .12 100 2.708/28/2006 1.63 77.6 .05 100 2.4
Appendixes 65

Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] 

Total mercury Methylmercury

Monitoring

station 

number

Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3

19 Maumee River at New Haven 08/27/2004 7.89 94.0 0.17 77 2.6

10/26/2004 3.92 83.1 .13 68 4.003/08/2005 5.83 60.5 .01 14 .706/21/2005 2.99 86.7 .15 63 7.008/30/2005 8.78 94.6 .36 84 4.612/06/2005 2.71 34.5 .07 100 .903/14/2006 20.93 77.8 .32 100 1.205/23/2006 21.69 92.0 .17 74 1.008/29/2006 11.50 92.0 .22 81 2.2

20 Fish Creek near Artic 09/07/2004 1.35 54.4 .09 56 6.5

10/26/2004 .38 38.0 .01 13 8.003/08/2005 1.96 48.4 .04 44 2.206/21/2005 .83 56.8 .05 33 10.308/30/2005 .55 56.1 .08 100 8.212/06/2005 .25 32.9 .06 100 7.903/14/2006 3.87 44.7 .03 33 1.005/23/2006 1.43 65.0 .12 67 8.208/29/2006 6.33 73.4 .21 100 2.4

21 St. Joseph River at Elkhart 09/07/2004 1.06 58.9 .00 0 5.6

10/27/2004 .94 72.3 ND ND ND03/09/2005 1.15 66.1 .03 38 4.606/22/2005 1.39 78.5 .02 25 4.508/31/2005 .66 68.8 .00 0 12.512/07/2005 .14 35.9 ND ND ND03/15/2006 6.77 74.8 .10 100 1.105/24/2006 1.72 73.5 .04 50 3.408/30/2006 2.79 85.3 .01 14 2.1
66 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] Total mercury Methylmercury Monitoring station number Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3 22 Trail Creek at Michigan City Harbor 09/08/2004 0.68 58.6 0.01 17 5.2 10/20/2004 .38 69.1 ND ND ND 03/09/2005 .59 41.5 .01 11 6.3 06/22/2005 1.13 79.0 .03 38 5.6 08/31/2005 .54 68.4 ND ND ND 12/07/2005 .49 59.8 ND ND ND 03/15/2006 3.80 64.0 .03 38 1.3 05/24/2006 1.46 78.5 .05 56 4.8 08/30/2006 3.84 53.7 .16 41 5.5 23 Deep River at Lake George outlet at Hobart 09/08/2004 1.28 59.3 ND ND ND 10/20/2004 1.26 68.1 ND ND ND 03/10/2005 .57 41.6 .08 100 5.8 06/23/2005 .81 56.6 .09 100 6.3 09/01/2005 .79 55.2 .05 100 3.5 12/08/2005 1.03 54.8 .05 100 2.7 03/16/2006 3.72 54.0 .00 0 .7

05/25/2006 .83 60.1 .05 100 3.608/31/2006 1.50 49.7 .04 27 5.0

24 Kankakee River at Shelby 09/08/2004 6.28 85.7 .07 54 1.8

10/21/2004 .61 76.3 ND ND ND03/10/2005 1.41 58.8 .04 40 4.206/23/2005 4.97 94.1 .00 0 .809/01/2005 1.66 91.2 .00 0 2.712/08/2005 .40 53.3 ND ND ND03/16/2006 8.71 71.4 .07 64 .905/25/2006 3.27 87.7 .07 100 1.908/31/2006 2.71 83.9 .07 100 2.2
Appendixes 67

Appendix 6. Estimated particulate total mercury and particulate methylmercury concentrations and methylation efficiencies in water samples from monitoring in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ng/L, nanograms per liter; ND, not determined; <, less than] 

Total mercury Methylmercury

Monitoring

station 

number

Station name Sample date (month/day/year) Estimated particulate1 (ng/L) Percentage of unfiltered2 Estimated particulate1 (ng/L) Percentage of unfiltered2 Methylation efficiency (percent)3

25 Wabash River at Vigo Street at Vincennes 10/07/2004 1.79 91.8 0.22 100 11.3

11/04/2004 8.04 82.6 .08 50 1.6

03/01/2005 2.12 51.5 .09 100 2.206/08/2005 2.20 86.6 .34 81 16.509/07/2005 2.15 88.1 .20 74 11.1

11/29/2005 3.19 77.6 .09 100 2.2

02/28/2006 4.40 78.0 .09 100 1.605/09/2006 5.92 91.8 .15 100 2.308/22/2006 3.48 90.2 .17 81 5.4

1Particulate mercury estimated by subtracting filtered concentration from unfiltered concentration.2Percentage unfiltered computed as the estimated particulate concentration divided by the unfiltered concentration, expressed as a percentage.3Methylation efficiency computed as unfiltered methylmercury concentration divided by unfiltered total mercury concentration, expressed as a percentage.
68 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] Monitoring station number Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance

(μS/cm)

Dissolved

oxygen

(mg/L)

Turbidity

 (ntru)

 1 Fall Creek near Fortville 08/23/2004 65 19.3 7.8 726 7.0 8.5

10/12/2004 28 11.9 8.0 810 8.4 2.302/22/2005 360 5.8 7.8 653 11.2 8.206/27/2005 78 23.3 7.8 746 6.4 1809/15/2005 36 21.0 7.8 775 6.4 1312/16/2005 95 1.4 7.8 832 13.0 3.203/10/2006 1,660 8.3 7.4 368 9.8 28005/15/2006 687 11.7 7.8 518 9.5 4209/05/2006 49 17.5 8.1 829 8.1 13

 2 Eel River near Logansport 08/30/2004 3,730 20.6 7.6 365 7.8 140

10/19/2004 244 9.4 8.2 688 11.2 1.503/17/2005 829 5.3 8.0 647 11.7 7.806/14/2005 611 22.6 7.7 650 6.5 1909/13/2005 115 21.6 7.9 684 7.9 3.412/13/2005 214 –.2 7.5 804 12.8 2.403/07/2006 378 2.3 8.2 708 14.1 3.905/17/2006 2,690 13.6 7.8 510 9.3 6509/07/2006 240 20.6 8.3 697 10.9 5.7

 3 Tippecanoe River at Winamac 09/02/2004 2,430 20.0 7.5 511 8.3 11

10/19/2004 360 8.8 8.1 643 10.1 2.503/17/2005 1,440 5.2 7.8 577 12.0 5.706/14/2005 508 23.8 8.0 604 7.5 1609/13/2005 172 22.6 8.0 657 7.9 5.612/13/2005 515 ND ND ND ND 5.003/07/2006 597 3.8 8.2 637 14.1 4.505/25/2006 1,460 17.3 8.0 608 9.3 1308/31/2006 1,240 19.8 7.7 518 6.9 36
Appendixes 69

Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] 

Monitoring

station 

number

Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance (μS/cm) Dissolved oxygen (mg/L) Turbidity (ntru)

 4 Wildcat Creek near Lafayette 08/30/2004 798 20.5 8.0 607 8.3 74

10/21/2004 409 12.1 8.3 640 11.2 8.103/16/2005 467 3.9 7.9 681 13.1 3.906/13/2005 446 22.8 7.9 679 7.8 1809/12/2005 67 22.6 7.9 762 8.2 5.512/12/2005 251 –.3 7.6 866 12.8 2.503/06/2006 365 3.6 8.3 730 13.3 3.005/17/2006 2,470 12.8 8.1 608 9.6 5109/07/2006 224 18.7 8.2 695 8.0 11

 5 Wabash River at U.S. Highway 40 at Terre Haute 09/10/2004 7,220 24.1 8.1 535 7.0 39

11/03/2004 9,430 15.7 8.0 597 7.7 6902/28/2005 26,700 5.3 7.8 508 12.1 4406/07/2005 4,410 27.8 8.0 572 12.0 3809/06/2005 2,130 28.8 8.0 649 5.5 3211/28/2005 4,840 9.8 8.1 632 11.2 3502/27/2006 8,190 5.6 8.0 663 13.8 7305/08/2006 9,510 19.3 8.4 654 11.1 4408/21/2006 3,210 30.7 8.7 548 ND 33

 6 Mill Creek at tailwater pool near Manhattan 08/31/2004 18 E 24.0 7.5 289 7.2 8.2

10/13/2004 39 E 18.6 7.2 302 8.1 9.503/04/2005 61 E 4.5 7.4 287 12.2 1306/06/2005 113 E 16.4 7.5 377 9.1 1309/02/2005 632 E 25.1 7.4 296 7.3 1712/02/2005 429 E 6.3 7.1 319 12.3 9.903/03/2006 136 E 4.9 7.8 445 14.5 1105/08/2006 273 E 14.0 7.3 396 10.1 1408/21/2006 12 E 24.8 7.9 310 6.8 14
70 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] Monitoring station number Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance

(μS/cm)

Dissolved

oxygen

(mg/L)

Turbidity

 (ntru)

 7 White River near Centerton 08/24/2004 975 23.6 7.6 998 7.2 15

10/14/2004 900 17.9 7.7 1,280 7.6 2002/23/2005 3,940 5.7 7.7 731 11.5 1906/28/2005 821 26.4 8.2 1,070 10.2 1509/14/2005 570 24.2 7.9 1,160 8.7 1512/14/2005 1,390 4.1 7.4 1,000 11.7 9.603/08/2006 1,560 8.4 7.8 962 11.3 6.905/16/2006 7,480 13.2 7.8 561 9.7 6009/06/2006 703 20.3 7.8 999 7.5 10

 8 White River near Nora 08/23/2004 516 23.1 7.7 878 7.3 10

10/12/2004 227 14.8 8.2 969 9.4 6.002/22/2005 2,360 4.6 8.0 577 11.9 1406/27/2005 386 26.9 7.8 865 6.6 1009/15/2005 300 23.4 7.7 905 6.7 1212/16/2005 662 1.3 7.8 857 13.8 4.303/10/2006 3,760 7.8 8.0 652 10.7 7705/15/2006 5,010 12.0 7.8 472 9.2 5909/05/2006 325 20.4 8.1 865 7.6 14

 9 Sugar Creek at New Palestine 08/24/2004 11 22.0 7.9 635 9.3 5.9

10/14/2004 9 12.9 7.9 657 7.1 5.202/23/2005 129 5.2 7.9 604 12.3 1006/28/2005 21 25.7 8.1 632 8.1 8.009/14/2005 11 22.5 7.9 621 9.6 4.312/14/2005 40 .6 7.7 728 14.0 6.003/08/2006 46 5.4 8.2 631 13.5 8.905/16/2006 346 12.5 7.8 508 9.6 3309/06/2006 11 18.3 8.2 668 8.8 5.0
Appendixes 71

Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] 

Monitoring

station 

number

Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance (μS/cm) Dissolved oxygen (mg/L) Turbidity (ntru)

10 East Fork Whitewater River at Brookville 09/03/2004 50 E 21.8 7.7 457 8.3 1.5

10/22/2004 468 E 16.2 7.8 446 9.5 1402/25/2005 307 E 3.9 7.8 418 12.5 7.806/30/2005 384 E 13.4 7.8 464 10.2 5.409/16/2005 60 E 17.7 7.6 473 10.0 1.112/19/2005 182 E 5.3 7.8 485 13.4 1.403/17/2006 1,690 E 5.8 8.3 503 13.8 1305/18/2006 2,010 E 9.5 8.0 492 12.5 2.909/08/2006 67 E 21.4 7.8 472 7.7 1.3

11 Vernon Fork Muscatatuck River at Vernon 08/25/2004 36 23.0 7.6 348 6.5 13

10/15/2004 139 13.4 7.9 729 7.4 2.602/24/2005 144 4.4 8.0 385 12.4 7.406/29/2005 8 26.7 8.4 412 7.5 9.309/19/2005 5 20.5 8.1 432 9.1 2.512/15/2005 65 1.8 7.8 508 13.9 1503/09/2006 2,030 6.8 7.4 180 11.1 18005/12/2006 296 14.3 7.8 261 8.9 6408/24/2006 7 25.3 8.1 308 8.8 4.6

12 White River at State Road 258 near Seymour 08/25/2004 688 24.8 7.9 640 8.3 8.0

10/15/2004 362 13.7 8.1 709 9.2 5.202/24/2005 3,440 5.9 7.8 622 11.4 1506/29/2005 1,090 27.5 8.3 615 11.0 1809/19/2005 694 22.8 8.1 708 9.4 9.912/15/2005 1,220 3.2 7.9 708 13.3 7.303/09/2006 6,740 6.7 7.7 334 10.4 29005/11/2006 6,660 16.2 7.8 422 7.5 26008/24/2006 758 25.3 8.2 665 8.7 9.4
72 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] Monitoring station number Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance

(μS/cm)

Dissolved

oxygen

(mg/L)

Turbidity

 (ntru)

13 Blue River at Fredericksburg 09/09/2004 20 20.5 7.9 454 8.2 9.2

10/18/2004 16 10.5 7.8 520 8.6 1303/03/2005 246 3.4 7.4 347 12.8 3.506/10/2005 33 24.3 7.7 469 7.1 1509/09/2005 10 20.7 7.5 435 6.5 1812/01/2005 302 5.8 7.7 332 13.2 1403/02/2006 151 10.1 7.9 378 11.7 5.405/11/2006 351 15.8 7.8 381 8.2 1708/24/2006 30 20.8 7.7 465 6.2 16

14 Patoka River at Winslow 09/01/2004 147 23.4 7.3 350 6.7 47

10/28/2004 1,220 16.1 7.2 303 5.3 24003/02/2005 1,240 4.4 7.4 269 11.0 2606/09/2005 47 25.9 7.5 626 9.4 5109/08/2005 57 22.6 7.2 436 6.1 3911/30/2005 621 8.0 7.1 398 8.8 16003/01/2006 218 6.4 7.3 353 12.7 1505/10/2006 598 17.1 7.2 275 7.5 4808/23/2006 311 24.1 7.2 235 5.2 61

15 White River at Petersburg 10/07/2004 1,780 18.6 8.1 831 9.9 35

10/28/2004 10,000 16.6 7.6 460 6.9 11003/02/2005 15,100 5.5 7.7 503 10.9 2606/09/2005 5,800 27.8 8.1 578 14.5 5309/08/2005 4,550 27.3 8.2 502 8.8 6111/30/2005 7,650 7.7 7.8 590 11.5 4103/01/2006 9,260 7.9 8.0 614 13.1 2205/10/2006 14,400 19.1 7.9 485 8.4 5208/23/2006 3,450 28.7 8.2 545 9.1 47
Appendixes 73

Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] 

Monitoring

station 

number

Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance (μS/cm) Dissolved oxygen (mg/L) Turbidity (ntru)

16 Busseron Creek near Carlisle 08/31/2004 102 E 23.0 7.5 863 7.3 33

10/29/2004 244 16.3 7.2 603 7.2 2403/01/2005 135 3.2 7.7 857 12.0 2206/08/2005 26 24.1 7.6 1,280 5.4 2709/07/2005 15 21.6 7.5 1,210 6.4 4411/29/2005 182 8.8 7.4 720 9.3 5702/28/2006 84 4.7 8.0 852 12.2 1605/09/2006 79 17.0 7.7 945 7.4 1408/22/2006 14 23.4 7.8 1,270 5.7 31

17 Mississinewa River at County Road 275 East near Peoria 08/26/2004 192 E 22.5 7.6 532 7.5 20

10/25/2004 194 E 12.8 7.7 575 9.7 4103/07/2005 574 E 4.2 8.0 562 12.8 2106/20/2005 248 E 20.2 7.8 478 9.0 5.208/29/2005 89 E 24.5 7.9 469 5.7 8.112/05/2005 570 E 3.4 7.4 545 13.2 3703/13/2006 2,020 E 6.5 8.0 511 12.6 2905/22/2006 673 E 14.0 7.9 458 10.4 2208/28/2006 141 E 22.8 7.5 481 4.5 9.4

18 Wabash River at County Road 200 West near Huntington 08/26/2004 92 E 23.8 7.7 599 7.9 36

10/25/2004 133 E 13.1 8.2 708 11.4 2603/07/2005 1,730 E 6.0 7.8 539 12.4 15006/20/2005 104 E 25.8 8.1 600 8.7 4708/29/2005 25 E 28.1 8.0 591 9.4 4612/05/2005 273 E .6 7.5 625 13.5 14003/13/2006 2,290 E 10.7 7.7 478 10.7 28005/22/2006 1,280 E 15.7 7.9 531 10.1 3608/28/2006 100 E 26.0 7.9 580 7.5 33
74 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] Monitoring station number Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance

(μS/cm)

Dissolved

oxygen

(mg/L)

Turbidity

 (ntru)

19 Maumee River at New Haven 08/27/2004 634 23.2 7.8 660 7.4 35

10/26/2004 591 12.8 7.7 795 8.6 4003/08/2005 4,020 4.6 7.4 493 12.5 11006/21/2005 106 22.0 7.8 813 9.3 2208/30/2005 145 24.5 7.4 905 4.4 3112/06/2005 1,300 –.1 7.5 580 11.9 12003/14/2006 8,140 9.3 7.7 384 10.4 50005/23/2006 2,530 14.5 7.8 548 9.3 6808/29/2006 1,380 22.6 7.6 525 5.4 92

20 Fish Creek near Artic 09/07/2004 15 20.9 8.2 619 7.0 21

10/26/2004 19 12.1 7.9 669 8.4 4.403/08/2005 336 2.3 7.7 392 12.3 3606/21/2005 10 18.9 8.0 671 8.3 2208/30/2005 6 20.4 8.0 692 7.7 9.512/06/2005 59 –.2 7.0 661 11.5 ND03/14/2006 592 6.7 7.8 373 10.2 9805/23/2006 71 14.0 8.0 533 8.8 1508/29/2006 157 19.0 7.6 391 6.6 86

21 St. Joseph River at Elkhart 09/07/2004 1,920 23.5 8.2 594 8.6 4.2

10/27/2004 1,560 13.0 7.9 618 9.9 2.703/09/2005 5,930 2.3 7.9 535 12.8 5.406/22/2005 1,790 22.3 7.8 586 8.6 4.508/31/2005 1,060 23.0 8.1 596 8.4 3.212/07/2005 1,200 .0 7.4 668 13.3 2.003/15/2006 6,030 6.9 8.1 496 11.4 5905/24/2006 4,140 16.1 8.1 584 9.7 6.508/30/2006 2,100 20.6 7.9 565 7.1 5.9
Appendixes 75

Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued[Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] 

Monitoring

station 

number

Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance (μS/cm) Dissolved oxygen (mg/L) Turbidity (ntru)

22 Trail Creek at Michigan City Harbor1 09/08/2004 –234 18.0 7.8 756 8.0 4.9

10/20/2004 583 12.3 7.8 757 11.4 4.103/09/2005 236 4.4 7.6 756 12.9 9.906/22/2005 179 21.0 7.9 772 9.3 1008/31/2005 –282 21.7 8.2 774 9.4 6.112/07/2005 –30 2.1 7.5 854 13.7 4.303/15/2006 49 7.6 7.9 702 11.2 4505/24/2006 –23 14.0 7.9 795 9.4 1308/30/2006 199 19.0 7.6 610 7.5 39

23 Deep River at Lake George outlet at Hobart 09/08/2004 36 22.7 7.9 666 8.1 16

10/20/2004 26 9.9 8.0 662 9.9 1803/10/2005 91 4.0 7.9 939 12.2 1506/23/2005 15 24.0 8.3 713 9.4 1909/01/2005 16 24.0 8.1 644 6.0 1612/08/2005 29 1.5 7.3 882 11.7 1903/16/2006 417 6.9 7.7 640 10.0 9105/25/2006 65 18.4 8.5 817 11.3 1208/31/2006 412 20.8 7.5 520 6.5 23

24 Kankakee River at Shelby 09/08/2004 2,390 20.2 7.7 597 7.4 23

10/21/2004 796 10.6 8.0 662 9.7 5.903/10/2005 3,440 3.4 7.8 602 11.6 1406/23/2005 676 22.9 7.9 687 7.9 2809/01/2005 629 21.6 7.9 739 7.5 1212/08/2005 1,240 –.3 7.7 766 12.7 8.203/16/2006 3,290 7.4 7.8 522 9.3 16005/25/2006 1,860 16.7 8.0 679 8.7 2108/31/2006 1,590 18.9 7.8 635 7.4 19
76 Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006 Appendix 7. Instantaneous streamflow and water-quality characteristics at monitoring stations for mercury in Indiana streams, August 2004–September 2006.—Continued [Locations of stations shown on figure 1; ft3/s, cubic foot per second; oC, degree Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; ntru, nephelometric turbidity ratio units; ND, no data; E, streamflow estimated with stage data and historical rating] Monitoring station number Station name Sample date (month/day/ year) Instantaneous streamflow (ft3/s) Water temperature (oC) pH (standard units) Specific conductance

(μS/cm)

Dissolved

oxygen

(mg/L)

Turbidity

 (ntru)

25 Wabash River at Vigo Street at Vincennes 10/07/2004 3,400

E 18.8 8.5 597 14.5 24

11/04/2004 15,500 15.1 7.6 506 7.7 9303/01/2005 35,200 4.4 7.6 487 11.8 4406/08/2005 5,660 27.5 8.0 609 8.3 2909/07/2005 2,340 27.1 8.3 570 11.6 3911/29/2005 6,050 7.7 7.8 624 11.0 4902/28/2006 9,560

E 6.3 8.5 605 13.0 98

05/09/2006 11,300

E 19.4 8.2 629 10.0 69

08/22/2006 4,150

E 28.0 8.6 539 13.6 54

1Instantaneous streamflow from Trail Creek at Michigan City Harbor includes positive values indicating a flow direction downstream toward nearby Lake Michigan and negative values indicating a flow direction 

upstream from Lake Michigan that were influenced by water levels in Lake Michigan.

Ulberg and Risch—Total Mercury and Methylmercury in Indiana Streams, August 2004–September 2006—Scientific Investigations Report 2008–5176

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