U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5105

Water-Quality and Biological Assessment of the Iowa River

and Tributaries Within and Contiguous to the Meskwaki

Settlement of the Sac and Fox Tribe of the Mississippi in

Iowa, 2006–07

Prepared in cooperation with the

Sac and Fox Tribe of the Mississippi in Iowa
Front cover. Background photograph is view along bend in Iowa River below Montour, IA, July 2007 (photograph taken by Jason McVay, 

USGS). Inset photograph shows USGS and Meskwaki Settlement field personnel collecting water-quality samples on a cross section of the 

Iowa River near Montour, Iowa, June 2006 (photograph taken by Greg Littin, USGS).

Back cover. Upper left photograph shows USGS hydrologist taking multiprob measurements of the Iowa River from the Avenue E bridge near 

Montour, IA (photograph taken by Doug Goodrich, USGS). Lower left photograph shows USGS hydrologic technician collecting water-quality 

sample from the Iowa River near the pow wow grounds, December 2006 (photograph taken by Greg Littin, USGS). Right inset photograph 

shows USGS and Meskwaki Settlement field personnel collecting and cataloging aquatic macroinvertebrate samples, July 2007 (photograph 

taken by Jason McVay, USGS).
Water-Quality and Biological Assessment 

of the Iowa River and Tributaries Within 

and Contiguous to the Meskwaki 

Settlement of the Sac and Fox Tribe of the 

Mississippi in Iowa, 2006–07

By Gregory R. Littin and Jason C. McVay

Prepared in cooperation with the Sac and Fox Tribe of the Mississippi in Iowa

Scientific Investigations Report 2009–5105

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Littin, G.R., and McVay, J.C., 2008, Water-quality and biological assessment of the Iowa River and tributaries within 

and contiguous to the Meskwaki Settlement of the Sac and Fox Tribe of the Mississippi in Iowa, 2006–07: U.S. 

Geological Survey Scientific Investigation Report, 2009–5105, 41 p. 
iii

Contents

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

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

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

Location and Population......................................................................................................................2

Physiographic Setting and Land Use ................................................................................................2

Climate....................................................................................................................................................4

Design and Methods of Data Collection ....................................................................................................4

Water-Quality Sampling Sites.............................................................................................................4

Biological Assessment Sites ..............................................................................................................4

Sampling Methods................................................................................................................................4

Laboratory Methods.............................................................................................................................6

Quality Assurance and Quality Control Methods ............................................................................7

Sampling Quality Control ............................................................................................................7

Field and Trip Blank Samples............................................................................................7

Field Replicate Samples ....................................................................................................7

Laboratory Quality Control .........................................................................................................7

Spike and Blank Samples and Surrogate Compounds.................................................7

Water-Quality Assessment...........................................................................................................................9

Surface-Water Setting.........................................................................................................................9

Streamflow Data ...................................................................................................................................9

Water-Quality Data.............................................................................................................................10

Physical Properties ...................................................................................................................11

Major Ions...................................................................................................................................11

Water Type.........................................................................................................................11

Dissolved Solids................................................................................................................11

Nutrients and Dissolved Organic Carbon ..............................................................................11

Trace Metals...............................................................................................................................14

Organic Compounds..................................................................................................................15

Pesticides...........................................................................................................................15

Wastewater Compounds .................................................................................................17

Fuel Compounds................................................................................................................20

Bacteria.......................................................................................................................................20

Total Suspended Solids.............................................................................................................20

Sediment-Quality Data.......................................................................................................................20

Trace Metals and Organic Compounds..................................................................................22

Biological Assessment................................................................................................................................22

Fish Community ...................................................................................................................................23

Benthic Macroinvertebrate Community .........................................................................................26

Periphyton (Algae)..............................................................................................................................27

Fish Tissue ...........................................................................................................................................28

Physical Habitat ..................................................................................................................................32

Summary and Conclusions.........................................................................................................................34

Acknowledgments..............................................................................................................................35
iv

References Cited..........................................................................................................................................35

Glossary.........................................................................................................................................................41

Appendixes ............................................................................................................... On CD-ROM in pocket

Appendix 1. Water-quality records for the Iowa River near Montour, Iowa (05451750) from 

water years 2006 to 2007.................................................................. On CD-ROM in pocket

Appendix 2. Water-quality records for Onion Creek below Highway 30 near Montour, Iowa 

(05451753) from water years 2006 to 2007 ..................................... On CD-ROM in pocket

Appendix 3. Water-quality records for Onion Creek near Montour, Iowa (05451754) from 

water years 2006 to 2008.................................................................. On CD-ROM in pocket

Appendix 4. Water-quality records for Raven Creek near Montour, Iowa (05451762) from 

water years 2006 to 2007 ................................................................. On CD-ROM in pocket

Appendix 5. Water-quality records for the Iowa River at Highway 49 near Tama, Iowa 

(05451770) from water years 2006 to 2007 ..................................... On CD-ROM in pocket

Appendix 6. Water-quality records for Bennett Creek near Tama, Iowa (05451773) from 

water years 2006 to 2007.................................................................. On CD-ROM in pocket

Appendix 7. Water-quality records for the Iowa River at Wetlands Reserve Property near 

Tama, Iowa (05451785) from water years 2006 to 2007................ On CD-ROM in pocket

Appendix 8. Water-quality records for Cattail Creek near Tama, Iowa (05451765) from water 

years 2006 to 2007.............................................................................. On CD-ROM in pocket

Appendix 9. Fish sample populations for the Iowa River within the Meskwaki Settlement, 

central Iowa, and for Onion Creek near Montour, Iowa, 2007... On CD-ROM in pocket

Figures

1. Map showing location of boundary of Meskwaki Settlement and water-quality and 

biological sampling sites along the Iowa River and associated tributaries in central 

Iowa ................................................................................................................................................3

2. Graph showing comparison of discharge measurements at streamflow gages 

upstream and downstream from sampling sites 1, 5, and 7 on the Iowa River at the 

Meskwaki Settlement, April 2006–September 2007..............................................................10

3. Trilinear diagram showing relative median compositions of surface water within and 

contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07.................12

4. Graphs showing concentrations of nitrate and phosphorus in surface water within and 

contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07.................14

5. Graphs showing concentrations of selected pesticides in surface water within and 

contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07.................18

6. Graphs showing bacteria densities in surface water within and contiguous to the 

Meskwaki Settlement, central Iowa, between April and October, water years 

2006–07 .........................................................................................................................................21

7. Graphs showing concentrations of median total suspended solids compared to median 

turbidity in surface water within and contiguous to the Meskwaki Settlement, central 

Iowa, water years 2006–07........................................................................................................22

8. Schematic diagram showing Fish Index of Biological Integrity (FIBI) qualitative scoring 

ranges in relation to a conceptual tiered (1–6) human disturbance gradient..................23

9. Schematic diagram showing Benthic Marcoinvertebrate Index of Biological Integrity 

(BMIBI) qualitative scoring ranges in relation to a conceptual tiered (1–6) human 

disturbance gradient..................................................................................................................26
v

Tables

1. Description of sampling-site locations within and contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07................................................................................5

2. Laboratory analytical methods used in the analysis of samples from the Meskwaki 

Settlement, central Iowa, water years 2006–07 ......................................................................6

3. Summary of analytical results for field blank and replicate samples for selected analytes, Meskwaki Settlement, central Iowa, water years 2006–07 ........................................8

4. Statistical summary of surface-water discharge at Iowa River and tributary sampling 

sites within and contiguous to the Meskwaki Settlement, central Iowa, water years 

2006–07 ...........................................................................................................................................9

5. Statistical summary of nutrient concentrations in water samples from the Iowa River 

and tributaries within and contiguous to the Meskwaki Settlement, central Iowa, water 

years 2006–07, and comparison to water-quality guidelines ..............................................13

6. Statistical summary of nutrient concentrations in water samples from the Iowa River 

at the Meskwaki Settlement, central Iowa, water years 2006–07, and the Wapsipinicon 

River near Tripoli, Iowa, water years 1996–04 .......................................................................15

7. Statistical summary of trace metal concentrations in water samples from the Iowa 

River and tributaries within and contiguous to the Meskwaki Settlement, central Iowa, 

water years 2006–07, and comparison to water-quality guidelines...................................16

8. Analytical results for selected pesticides in water samples from the Iowa River and 

tributaries within and contiguous to the Meskwaki Settlement, central Iowa, water 

years 2006–07, and comparison to water-quality guidelines ..............................................17

9. Frequency of quantifiable pesticide detections in water samples from the Iowa River 

and tributaries within and contiguous to the Meskwaki Settlement, central Iowa, water 

years 2006–07 ..............................................................................................................................19

10. Frequency of quantifiable wastewater compound detections in water samples from 

the Iowa River and tributaries within and contiguous to from the Iowa River and 

tributaries within and contiguous to at the Meskwaki Settlement, central Iowa, water 

years 2006–07 ..............................................................................................................................19

11. Relations between quantifiable and unquantifiable wastewater compound detections 

in water samples from the Iowa River and tributaries within and contiguous to the 

Meskwaki Settlement, central Iowa, water years 2006–07.................................................20

12. Statistical summary of escherichia coli (E. coli) densities at selected sampling sites 

along the Iowa River and tributaries within and contiguous to the Meskwaki Settlement, central Iowa, between April and October, water years 2006–07.............................24

13. Statistical summary of selected trace metals in streambed-sediment samples from the 

Iowa River in comparison to samples from Onion Creek, Meskwaki Settlement, central 

Iowa, August 2007.......................................................................................................................25

14. Fish Indexes of Biological Integrity (FIBI) for fish community data collected from the 

Meskwaki Settlement, central Iowa, 2007..............................................................................27

15. Benthic Macroinvertebrate Index of Biological Integrity (BMIBI) for benthic macroinvertebrate data collected from the Meskwaki Settlement, central Iowa, 2007 ...............27

16. Weighted average (WA) results for periphyton community data collected from the 

Meskwaki Settlement, central Iowa, 2007..............................................................................28

17. Trophic conditions defined for periphyton community data collected from the 

Meskwaki Settlement, central Iowa, 2007..............................................................................29

18. Trophic condition results for periphyton community data collected from the Meskwaki 

Settlement, central Iowa, 2007 .................................................................................................29
vi

19. Comparison of consumption advisory protocols for whole or fillet fish-tissue 

samples ........................................................................................................................................30

20. Results of analysis of selected organochlorine pesticides in whole or fillet fish-tissue 

samples collected from the Meskwaki Settlement, central Iowa, 2007............................31

21. Results of analysis of selected organochlorine pesticides in fish liver or liver dilution 

samples collected from the Meskwaki Settlement, central Iowa, 2007............................31

22. Results of analysis of selected trace metals in fish liver samples collected from the 

Meskwaki Settlement, central Iowa, 2007..............................................................................32

23. Results of analysis of selected organic wastewater contaminants in fish-tissue 

samples collected from the Meskwaki Settlement, central Iowa, 2007............................32

24. Individual metrics for Ohio Environmental Protection Agency Qualitative Habitat Evaluation Index (QHEI) used in the physical habitat assessment .............................................33

25. Results of Qualitative Habitat Evaluation Index (QHEI) assessment of physical habitat 

data collected from the Meskwaki Settlement, central Iowa, 2007...................................33

Conversion Factors and Abbreviations

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square meter (m2) 4,046.856 acre

square mile (mi2) 2.590 square kilometer (km2

) 

Flow rate

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

/s)

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

/d)

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

°F=(1.8×°C)+32.

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

°C=(°F-32)/1.8.

Horizontal coordinate information is referenced to the insert datum name (and abbreviation) 

here for instance, “North American Datum of 1983 (NAD 83).”

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).

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

or micrograms per liter (μg/L).

Streambed-sediment concentrations are given in micrograms per gram (μg/g).

Bacteria densities are measured in the number of colony-forming units per 100 milliliters of 

water (cfu/100 mL). 
vii

Acronyms Used in Report

ANSP Academy of Natural Sciences of Philadelphia

BMIBI Benthic Macroinvertebrate Index of Biological Integrity

CALFED California Federal

CIAT 2-Chloro-4-Isopropylamino-6-Amino-s-Triazine

DDT Dichloro-Diphenyl-Trichloroethane

DELT Deformities Eroded fins Lesions Tumors

DOC Dissolved Organic Carbon

EPA Environmental Protection Agency

EWI Equal Width Increment

FDA U.S. Food and Drug Administration

FIBI Fish Index of Biological Integrity

HQR High Quality Resource

IBI Index of Biotic Integrity

IDNR Iowa Department of Natural Resources

IEPA Illinois Environmental Protection Agency

IDPH Iowa Department of Public Health

LRB Laboratory Reagent Blank

LRL Laboratory Reporting Level

LRS Laboratory Reagent Spike

LT-MDL Long-Term Method Detection Level

MCL Maximum Contaminant Level

MRL Minimum Reporting Limit

MTBE Tert-Butyl Methyl Ether

NAWQA National Water Quality Assessment

NOAA National Oceanographic and Atmospheric Administration

NWQL National Water Quality Laboratory

PAH Polycyclic Aromatic Hydrocarbon

PBDE PolyBrominated Dephenyl Ether

PCB PolyChlorinated Biphenyls

PEL Probable Effects Level

QA Quality Assurance

QC Quality Control

QHEI Qualitative Habitat Evaluation Index

QMH Qualitative Multihabitat

RPD Relative Percentage Difference

RTH Rich Targeted Habitat

SM Standard Method

SMCL Secondary Maximum Contaminant Level

SOP Standard Operating Procedure

SV Screening Value
Acronyms Used in Report—Continued

TEL Threshold Effects Level

TN Total Nitrogen

TSS Total Suspended Solids

UHL University Hygienic Laboratory

USACOE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency

WRP Wetlands Reserve Property
Abstract 

In cooperation with the Sac and Fox Tribe of the Mississippi in Iowa (Meskwaki Nation), the U.S. Geological Survey 

conducted a 2-year baseline assessment of the chemical and 

biological quality of streams within the Meskwaki Settlement 

in central Iowa. The Meskwaki Nation is a federally recognized tribe that wishes to establish water-quality standards 

to safeguard the integrity of surface waters and aquatic biota 

within the settlement for the health and welfare of the tribal 

community. The settlement is drained by the Iowa River and 

four tributaries (Onion, Cattail, Raven, and Bennett Creeks). 

Water-quality samples were collected at three sites on the 

Iowa River, two sites on Onion Creek, and one site each on 

Cattail, Raven, and Bennett Creeks from April 2006 through 

July 2007. Biological and habitat assessments were conducted 

at all three sites on the Iowa River and the downstream-most 

site on Onion Creek from June through August 2007. Analysis 

of physical properties, major ions, nutrients, trace compounds, 

bacteria, and total suspended solids in water, and trace metals 

and organic compounds in streambed sediment provided information about the effects of anthropogenic (human related) 

activities on the water quality of settlement streams. Analysis 

of biological samples collected during the summer of 2007, 

including fish community, benthic macroinvertebrates, and 

periphyton samples, as well as physical habitat characteristics, 

provided information on the effects of water quality on the 

condition of the aquatic environment. 

 The majority of surface water sampled within the settlement was predominately a calcium bicarbonate type. Nitrates 

(nitrate plus nitrite as nitrogen) exceeded the U.S. Environmental Protection Agency’s (USEPA) primary drinking-water 

Maximum Contaminant Level of 10 μg/L in 19 of 36 samples 

from sites on the Iowa River and Raven and Bennett Creeks 

but not in samples from Onion and Cattail Creeks. None of the 

samples analyzed for pesticides, trace metals, wastewater, or 

fuel contaminants were found to exceed drinking-water regulations for the USEPA or State of Iowa targeted constituents. 

Bacteria densities for Escherichia coli (E. coli) ranged from 

less than 10 to more than 600,000 colony-forming units per 

100 milliliters of water and were largest following intense 

rainfall runoff. The largest densities were recorded in samples 

collected from the tributaries, most notably from Cattail Creek 

downstream from the tribal headquarters area and Onion 

Creek downstream from the sewage lagoons. Arsenic and 

nickel concentrations in bottom sediment from Onion Creek 

exceeded the USEPA threshold effects level in a composite 

sample collected during the habitat assessment in July 2007. 

Suspended-sediment concentration was estimated in terms of 

total suspended solids. Overall, Onion and Bennett Creeks 

were the least turbid, whereas the ephemeral Cattail Creek had 

the most turbid samples. 

Aquatic-community data were collected at four sites 

on the Meskwaki Settlement during the summer of 2007 to 

provide a baseline biological assessment of stream conditions. 

This assessment was based on sampling of the fish, benthic 

macroinvertebrate, and periphyton communities along with 

physical habitat characteristics. Individual biological metrics 

were derived from the data collected during the community 

surveys. These metrics were used to calculate Indexes of 

Biological Integrity (IBIs). The calculated values from the 

IBIs provided a numerical value that was used to provide an 

assessment of the biological condition at each biological sampling site. The fish community samples indicated that all of the 

sampling sites would be considered in fair condition, with one 

exception being a collection site on the Iowa River at Highway 

49 near Tama, Iowa, which was classified in poor condition. 

The benthic macroinvertebrate IBI indicated a classification 

of good for three of the four biological sampling sites, with 

the Iowa River near Montour, Iowa, site classified as fair. The 

periphyton community assessment indicated that the potential 

for eutrophic conditions exists on the basis of the species that 

are present in the streams at all of the biological sampling 

sites. The physical in-stream habitat and proximate-riparian 

habitat indicate that the Iowa River sites are in fair condition 

and that the Onion Creek site is in poor condition. A cause for 

Water-Quality and Biological Assessment of the Iowa 

River and Tributaries Within and Contiguous to the 

Meskwaki Settlement of the Sac and Fox Tribe of the 

Mississippi in Iowa, 2006–07 

By Gregory R. Littin and Jason C. McVay
2 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

this difference in classification would be that the Onion Creek 

site has had greater effects from anthropogenic sources.

Fish-tissue samples, both fillet and liver, were collected to provide an assessment of current fish health and the 

potential effects on human health related to the contaminants 

present in fish tissue. Both cadmium and mercury were found 

in liver samples at concentrations that would warrant fish-consumption advisories. The insecticide dieldrin was also detected 

at all sites in both the fillet and liver samples at concentrations greater than USEPA risk-based screening values. A few 

organic wastewater contaminants also were found in fishtissue samples; a class of chemicals known as polybrominated 

dephenyl ethers (PBDEs), a flame retardant, was found at all 

four sites in both fillet and liver samples. Other organic wastewater contaminants found in the whole fish samples from the 

Onion Creek site were triclosan, an antimicrobial disinfectant, 

and its degradate methoxytriclosan. The fish-tissue sample 

results indicated the need for further study of contamination 

levels and potential health effects so that effective fish-consumption advisory levels can be developed for the Meskwaki 

Settlement. 

Introduction

The Sac and Fox Tribe of the Mississippi in Iowa 

(Meskwaki Nation) is a federally recognized Native American 

Tribe. Tribal lands include about 7,300 acres encompassing the Meskwaki Settlement near Tama in central Iowa 

and another 700-acre tract in Palo Alto County in northwest 

Iowa. This study was conducted on surface water within and 

contiguous to the settlement in central Iowa. The Iowa River 

flows through the southern part of the settlement from west to 

east and is the major waterway in the area. The tribal members 

depend on the river for supplemental sustenance from fish and 

game that normally inhabit the riverine areas. 

In 2006, the Meskwaki Nation cooperated with the U.S. 

Geological Survey (USGS) to conduct a baseline study that 

included periodic sampling and analysis of water samples 

from the Iowa River and local tributaries (Onion, Cattail, 

Raven, and Bennett Creeks) to determine (1) ranges in the 

quality of water at selected sampling sites, (2) exceedances 

of State or Federal water-quality standards, and (3) ranges of 

constituent concentrations in bed sediment in sampled streams. 

Analyses of physical properties, major ions, nutrients, trace 

metals, organic compounds, bacteria, and sediment provided 

information about the effects of anthropogenic (humanrelated) activities on the water quality of settlement streams. 

In addition, a biological assessment was conducted during the 

summer of 2007 to determine the overall condition of aquatic 

life in streams within the settlement. The biological samples 

included fish community, benthic macroinvertebrates, and 

periphyton samples, as well as physical habitat characteristics. 

Purpose and Scope

The purpose of this report is to describe a surface-waterquality and biological assessment for use in the determination 

of baseline conditions and the design and implementation of 

tribal water-quality-related programs. The data will be used 

as a basis for developing realistic water-quality standards 

for surface water on the settlement. The scope includes a 

presentation and analysis of data including periodic measurements of streamflow and surface-water quality (April 2006 

to July 2007), streambed sediment (June and July 2007), 

and biological and habitat assessments (June 2007 to August 

2007). Streamflow data include discharge and stage measurements from three main-stem sites and four tributaries 

to the Iowa River. Water-quality analyses were conducted 

on samples collected during base-flow, intermediate, and 

storm-flow conditions.

Location and Population

The Meskwaki Settlement in central Iowa is located 

about 40 miles (mi) west of Cedar Rapids near the towns of 

Toledo and Tama (fig. 1). The settlement was established 

in 1857 on 80 acres of land purchased by tribal members a 

year after they were granted residential status from the Iowa 

General Assembly. Through additional land purchases, the 

original 80 acres now forms the core of more than 7,300 acres 

of tribal land. 

Approximately 650 of nearly 1,300 tribal members live 

on the settlement (Bob Hipple, Meskwaki Natural Resources 

Department, oral commun., 2006). Members generally reside 

near the boundaries of the settlement, and as with most tribal 

lands, there is no individual ownership. 

Physiographic Setting and Land Use

The settlement is in the landform region known as the 

Southern Iowa Drift Plain, which is dominated by glacial 

deposits left by ice sheets that covered this region between 

2.5 million and 500,000 years ago (Iowa Department of 

Natural Resources, 1997). The deposits then were carved by 

deepening episodes of stream erosion. Native surface and 

near-surface sediment in the northern area of the settlement 

consists of gently sloping to very steep, well-drained, silty 

soils formed in loess on uplands to nearly level, moderately 

well-drained and poorly drained silty soils formed in alluvium on flood plains and low terraces (Iowa Department of 

Natural Resources, 2005). Topographic relief varies from a 

high of 1,000 feet (ft) in the northern and eastern parts of the 

settlement to a low of 825 ft near the Iowa River valley in the 

southeastern part of the settlement. The Iowa River enters the 

settlement at the southwest boundary at sampling site 1 and 

flows in a southeasterly direction where it forms the southern 

boundary of much of the settlement (fig. 1). 
Introduction 3

Wetlands

Reserve

Property

Bison pasture

Montour 

0.3 mile

Union Pacific Railroad

Marshalltown

15 miles

Pow wow

grounds

Toledo 3N

Sewage 

lagoons

Casino

Tribal

Headquarters

Base from U.S. Geological Survey digital data, 1:100,000, 2006

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

Trading

post

1 3

5

6

4

8

2

7

92°42’30” 40' 37’30” 92°35’

42°00’

42°02’30”

41°57’30”

0 1

0 1 2 KILOMETER

2 MILE

U.S. Highway 30

U.S. Highway 30

Highway 49

U.S. Highway 63

U.S. HIghway 63

Orthophotograph modified from Farm Services Administration,

National Agriculture Imagery Program, 2007

Iowa

Rive

R

r

aven Creek

Bennett Creek

Cattail Creek

Tama

O

Toledo nion Creek

6

EXPLANATION

Property boundary of Meskwaki Settlement 

Water-quality sampling site and identifier

Water-quality and biological sampling site

 and identifier

National Weather Service precipitation gage

 and identifier

U.S. Army Corps of Engineers streamflow-

 gaging station

U.S. Geological Survey streamflow-gaging 

 station and number (on index map)

5

Toledo 3N

Marshalltown

05453100

05451500

05420680

05451500

Study area

Tripoli

Skunk

River

North Skunk River

South Skunk River

Richland Creek

IOWA

Index map

Haven Marengo

Rosehill

Wapsipinicon River

Iowa

River

Palo Alto

County

Figure 1. Location of boundary of Meskwaki Settlement and water-quality and biological sampling sites along the Iowa 

River and associated tributaries in central Iowa.
4 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Land is used for rural residential, agricultural, recreational, commercial, livestock, and conservational purposes. 

The latter represents about 40 percent of all land-use cover 

and includes much of the wetlands along the Iowa River corridor. Vegetation consists of cottonwood, silver maple, and oak 

along the Iowa River and its tributaries. Cedar, maple, hickory, 

and oak commonly are found throughout the east residential 

area surrounding the tribal headquarters. Prairie grasses, such 

as big and little blue stem, fill much of the open areas. Agriculture is limited and consists of corn and soybeans in the central 

part of the settlement bounding Onion Creek. Small amounts 

of alfalfa are grown in the north-central area north of State 

Highway 30 and on the Wetlands Reserve Property (WRP) 

near Tama. Livestock consists of bison maintained on noncontiguous property south of the southern boundary of the main 

settlement area (Kelly Schott, Meskwaki Natural Resources 

Department, oral commun., 2007). 

Historically, the Meskwaki Nation has maintained a society that is based on hunting, gathering, and farming. In recent 

years, the economic base of the tribe has shifted to retail commerce and gaming. Commercial enterprises include a resort 

hotel, casino, and trading post located along Highway 30 near 

the northern boundary of the settlement. 

Climate

The climate throughout the settlement is temperate. 

Average daily high temperatures generally vary from the low 

80 degrees Fahrenheit (oF) during the summer months to the 

mid-20s oF during the winter. Precipitation averages about 

34 inches per year (in/yr) on the basis of State of Iowa climate 

records for Toledo (Iowa Department of Agriculture, 2007). 

However, precipitation measured at the National Weather 

Service (NWS) Toledo 3N gage (fig. 1) was 22.38 inches (in.) 

during 2006 and 30.96 in. during 2007. Precipitation measured 

at the NWS Marshalltown gage, about 15 miles northwest of 

the settlement, was 34.23 and 35.66 in., respectively, for the 

same periods of record (Iowa State University Department of 

Agronomy, 2007). 

Design and Methods of Data Collection 

Water-Quality Sampling Sites

Sampling locations are listed in table 1 and shown in figure 1. Eight sites were selected for water-quality and sediment 

sampling using methods described in Averett and Schroder 

(1994) and Edwards and Glysson (1999). Sites represent combinations of natural and human factors thought to collectively 

affect the physical, chemical, and biological characteristics 

of surface-water quality on the settlement with the objective 

of answering questions regarding source, occurrence, effects, 

and spatial distribution of potential contaminants. These sites 

were located upstream from backwater during both low- and 

high-flow conditions and were accessible for sampling on the 

basis of site characteristics and landowner permission. Some 

sampling sites were at or near road overpasses or bridges so 

that safe access could occur during high-flow sampling.

Biological Assessment Sites

Biological assessments were conducted along three 

reaches of the Iowa River and one reach of Onion Creek 

(table 1; fig. 1) on the basis of protocols and guidelines 

detailed in Barbour and others (2002), Moulton and others (2002), and Fitzpatrick and others (1998). In general, 

reach lengths ranged from about 500 to 1,000 ft for wadeable streams and from about 1,500 to 3,000 ft for nonwadeable streams. Characterization of physical habitat included 

documentation of general land use, description of the stream 

origin and type, summary of the riparian vegetation features, 

and measurements of in-stream characteristics such as width, 

depth, flow, water-surface gradient, and substrate. Each proposed site was named and identified by a site number and a 

location description, as well as by its latitude, longitude, and 

elevation, as determined by global positioning system (U.S. 

Environmental Protection Agency, 1992; Federal Geographic 

Data Committee, 1998). 

Sampling Methods

Stream discharges were measured and water-quality samples were collected by USGS and Meskwaki personnel at three 

locations on the Iowa River and at five locations on four tributaries that drain the settlement (table 1; fig. 1) using methods 

described in Rantz and others (1982) and Wilde and Radtke 

(1998). Six synoptic measurements were performed during the 

first year of this study (April 2006 – July 2007) and included 

base- and storm-flow conditions (low-flow and high-flow conditions). Additionally, water-quality samples were collected 

at each of the four habitat sites (sites 1, 3, 5, and 7) during the 

second year of the investigation (June–August 2007). Waterquality sampling entailed parts-per-billion, equal-width- increment sampling methods (Edwards and Glysson, 1999). Sampling instrumentation included a Yellow Springs Instrument’s 

multiprobe meter (YSI Corporation, Yellow Springs, OH) for 

collecting water-quality physical properties, a USGS DH-81 

for collecting water-quality samples at wadeable sites, and a 

USGS D-95 depth-integrated sampler for collecting samples at 

nonwadeable sites.

Following discharge measurements, instantaneous 

measurements of water properties (specific conductance, pH, 

temperature, and dissolved-oxygen concentration) were made. 

Water samples then were collected for major ions, nutrients, 

trace metals, pesticides, wastewater compounds, polycyclic 

aromatic hydrocarbons (PAHs, fuel compounds), and escherichia coli (E. coli) and fecal coliform bacteria. As part of 

onsite training, Meskwaki Nation staff assisted in the collection of samples during both low- and high-flow conditions.
Design and Methods of Data Collection 5

Biological surveys were made during the summer of 

2007 on fish, benthic macroinvertebrate, and physical 

habitat. The sampling methods for the collection of fish, 

macroinvertebrates, and periphyton used during the survey 

period followed the protocol discussed in Moulton and others 

(2002). The surveying methods used for collection of physical 

habitat data are outlined in Fitzpatrick and others (1998).

During fish sampling, the data were collected using directcurrent electrofishing equipment mounted on either a 

backpack or boat depending on the stream depth (Moulton 

and others, 2002). The fish-sampling methods used by the 

USGS for both wadeable and large river sites are similar to the 

methods used by the Iowa Department of Natural Resources 

(IDNR; Iowa Department of Natural Resources, 2006), and 

the Ohio Environmental Protection Agency (Ohio EPA; 

Ohio Environmental Protection Agency, 1987). Fish-tissue 

samples were collected and processed according to Crawford 

and Luoma (1992) and shipped to the USGS National Water 

Quality Laboratory (NWQL) in Denver, Colorado, for 

contaminant analysis. Fish collected during the sampling 

period were identified on site by a U.S. Fish and Wildlife 

Service (USFWS) biologist to the species level. All fish were 

returned to the water within the reach sampled other than the 

fish that were sent into the NWQL for tissue contamination 

analysis.

Macroinvertebrate data were collected using two methods, the first being rich-targeted habitat (RTH) and the second 

being qualitative multihabitat (QMH), which are described 

further in Moulton and others (2002). The RTH samples were 

hand samples of woody snags collected at five discrete locations throughout each sampling reach at what is considered 

the most abundant and best representative habitat available. 

The QMH samples are collected with a D-frame kick net at all 

available habitat types within the reach in a designated amount 

of time. When using the IDNR Index of Biotic Integrity 

(IBIs), the IDNR standard habitat sample is comparable to 

the USGS RTH sample and the IDNR multihabitat sample is 

comparable to the USGS QMH sample. Both the RTH and the 

QMH samples are used in the IBI calculations. Macroinvertebrate samples were composited and preserved in 10-percent 

buffered formalin and sent to the NWQL for identification and 

enumeration of organisms. 

Periphyton composite samples were preserved with 

a final concentration of 5-percent buffered formalin and 

shipped to the Academy of Natural Sciences of Philadelphia, Pennsylvania (ANSP). Identification and enumeration 

Table 1. Description of sampling site locations within and contiguous to the Meskwaki Settlement, central Iowa, water years 

2006–07.

[All water-quality and sediment samples were composite samples collected using the equal width increments (EWI) method (Edwards and Glysson, 1999). 

Shaded rows are comprehensive sampling sites and include periodic water and sediment sampling, and a biological and habitat assessment; mi2, square miles]

Site 

number

(fig. 1)

Site name

Drainage 

area 

(mi2)

Location and selection rationale

1 Iowa River near Montour, IA 1,840 Western boundary of the settlement provides baseline 

data for water entering the settlement. Water-quality 

and biological assessment site. 

2 Onion Creek below Hwy 30 near Montour, IA 5.0 Tributary to the Iowa River that drains the northern 

settlement housing area, enters upstream from casino 

sewage lagoons. Water quality only.

3 Onion Creek near Montour, IA 5.3 Site is downstream from outflow of casino sewage 

lagoons near mouth of Onion Creek. Water-quality 

and biological assessment site.

4 Raven Creek near Montour, IA 26.3 Raven Creek at Highway 49 to determine if this creek is 

a possible source of contamination to the Iowa River. 

Water quality only.

5 Iowa River at Highway 49 near Tama, IA 1,882 This is a culturally significant site for the Meskwaki 

Nation and a site of recreation for tribal members. 

Water-quality and biological assessment site. 

6 Bennett Creek near Tama, IA 7.0 Tributary to Iowa River entering on the south side of 

settlement. Site of restoration project for settlement as 

well. Water quality only. 

7 Iowa River at Wetlands Reserve Property (WRP) near 

Tama, IA

 1,896 Last piece of tribally owned land that the Iowa River 

passes through before it leaves the settlement. Waterquality and biological assessment site.

8 Cattail Creek near Tama, IA 1.8 Ephemeral discharge from tribal housing area. 

Storm-flow site, water quality only. 
6 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

of periphyton species were performed for each sample by 

the ANSP. 

Physical habitat characteristics were collected according 

to USGS protocol discussed in Fitzpatrick and others (1998). 

The IBI that was used to assess the condition of the physical habitat on the Meskwaki Settlement was the Qualitative 

Habitat Evaluation Index (QHEI), which was developed by 

the Ohio EPA (Ohio Environmental Protection Agency,1987). 

The QHEI index metrics are included within the data that are 

collected when following the USGS protocol.

Suspended- and bed-sediment samples were collected 

at selected stream locations in conjunction with the physical 

habitat evaluation (fig. 1; table 1). Analytes included trace 

metals and pesticides. All aspects of sample collection were 

conducted in accordance with guidelines and procedures as 

described in Wilde and Radtke (1998). 

Laboratory Methods

Water samples were analyzed at the USGS NWQL for 

major ions using atomic absorption spectrometry as described 

in Fishman and Friedman (1989); nutrient concentrations 

by ion-exchange chromatography and colorimetric methods 

(Fishman, 1993); and trace metal concentrations in water and 

bed sediment using methods described in Faires (1993) and 

Briggs and Meier (1999), respectively. Pesticide compounds in 

water, bed sediment, and wastewater were analyzed at NWQL 

using gas chromatographic/mass spectrometric methods 

described in Foreman and others (1995), Zaugg and others 

(1995), Furlong and others (1996), and Zaugg and others 

(2002). Fuel compounds (PAHs) in water were analyzed at the 

NWQL according to methods described in Connor and others 

(1998). Water samples were analyzed at the University of 

Iowa Hygienic Laboratory for E. coli and fecal coliform densities using standard methods 9213D and 9222D, respectively 

(University Hygienic Laboratory, 2004; table 2). Pesticide 

and trace metal concentrations in fish tissue were determined 

by the NWQL according to Leiker and others (1995), Hoffman (1996), and U.S. Environmental Protection Agency 

(USEPA;1996). 

Laboratory methods included the analysis of water, bed 

sediment, and fish tissue for pesticides and metals. Accuracy 

and precision were determined by analyzing laboratory replicate samples and monitoring recovery of surrogates. Laboratory turnaround times varied by sample medium and procedure 

but were generally within 30 days of the sample login date. 

Laboratory standard operating procedures (SOPs) were consistent with USEPA requirements as specified in the method.

The USGS National Water Quality Laboratory collects 

quality-control data on a continuing basis to evaluate selected 

analytical methods to determine long-term method detection 

levels (LT–MDL’s) and laboratory reporting levels (LRL’s). 

These values are re-evaluated each year on the basis of the 

most recent quality-control data and, consequently, may 

change from year to year. 

This reporting procedure limits the occurrence of false 

positive error. The chance of falsely reporting a concentration 

greater than the LT–MDL for a sample in which the analyte is 

not present is 1 percent or less. Application of the LRL limits 

the occurrence of false negative error. The chance of falsely 

reporting a non-detection for a sample in which the analyte is 

present at a concentration equal to or greater than the LRL is 

1 percent or less. 

Accordingly, concentrations are reported as <LRL for 

samples in which the analyte was either not detected or did not 

Table 2. Laboratory analytical methods used in the analysis of samples from the Meskwaki Settlement, central Iowa, water years 

2006–07. 

[USGS, U.S. Geological Survey; USEPA, U.S. Environmental Protection Agency; UHL, University Hygienic Laboratory; CALFED, California Federal; SM, 

standard method]

Group Medium Schedule Method reference

Major ions Surface water USGS 2750 Fishman and Friedman (1989); USEPA 200.7/300.0A

Nutrients Surface water USGS 2752 Fishman and Friedman (1993); USEPA 200.7/350.1/353.2/365.1/365.4

Trace metals Surface water USGS 2703 Faires (1993); USEPA 200.7/200.8/908.0/1631 

Bed sediment USGS 2420 Briggs and Meier (1999); CALFED-D16

Fish tissue USGS 2200 Hoffman (1996); USEPA (1996); CALFED-D16

Organic compounds

Pesticides Surface water USGS 2001 Zaugg and others (1995); USEPA 507/8141

Bed sediment USGS 2200 Foreman and others (1995), Furlong and others (1996); USEPA 8081A

Fish tissue USGS 2101 Leiker and others (1995); USEPA 8081A/8141

Wastewater contaminants Surface water USGS 1433 Zaugg and others (2002); USEPA 508/8081A

Fuel compounds Surface water USGS 1378 Connor and others (1998); USEPA 8260

Bacteria Surface water UHL SM9213D, SM9221B/E, SM9222B/D, SM9223B
Design and Methods of Data Collection 7

pass identification. Analytes that are detected at concentrations 

between the LT–MDL and LRL and that pass identification 

criteria are estimated. Estimated concentrations will be noted 

with a remark code of “E.” These data should be used with 

the understanding that their uncertainty is greater than that 

of data reported without the “E” remark code (Childress and 

others, 1999). 

Quality-Assurance and Quality-Control Methods

Quality assurance (QA) is defined as the procedures used 

to control the ummeasurable components of the sample collection, processing, and analytical methods (Pirkey and Glodt, 

1998). QA elements include SOPs, sample and analysissequence protocols, instrument maintenance logs, and personnel training records. Quality-control (QC) data are collected 

to measure bias and variability of the sample and analytical 

methods and may include replicate, blank, spike, surrogate 

samples, and standard reference materials (Mueller and others, 

1997). In this study, surface-water samples were collected 

in accordance with “Methods for Collection and Processing of Surface-Water and Bed-Material Samples for Physical 

and Chemical Analyses” (Ward and Harr, 1990). Analyses of 

water-quality analytes were conducted using QA/QC practices 

of the NWQL, as described in Farrar (1997). Analytical results 

of quality-control samples are given in table 3 and appendixes 

1 through 8 (on CD-ROM in back of this report). All QA/QC 

procedures were conducted in accordance with the USEPAapproved ”Quality Assurance Project Plan” for the study 

described in this report (on file with the USGS in Iowa City, 

Iowa). 

Sampling Quality Control

Field and Trip Blank Samples 

A field blank sample is used to demonstrate that sampling 

equipment has been cleaned adequately to remove potential 

contamination introduced by samples collected at previous 

sites, that sample collection and processing have not resulted 

in contamination, and that sample handling and transport have 

not resulted in contamination. Blank samples were prepared 

by passing laboratory certified deionized water through all 

sampling equipment to verify cleanliness of the equipment. 

Nutrient, pesticide, and wastewater contaminant concentrations were analyzed in 11 field blank samples and compared 

to subsequent environmental samples. A trip blank sample, 

used to identify contamination that might occur during sample 

transport and analysis, was collected at sampling site 2 to test 

for potential volatile organic contamination. 

Field Replicate Samples 

A field replicate sample is defined as a second sample (or 

measurement) from the same location, collected in immediate 

succession, using identical techniques. Field replicate samples 

commonly are drawn from environmental samples and are 

used to estimate the precision of sample processing and 

analysis. Such samples are prepared by partitioning a larger 

environmental sample from one container into subsamples; 

samples are split in an enclosed environment using equipment 

and methods that preclude sample contamination. Replicate 

samples are sealed, handled, stored, shipped, and analyzed in 

the same manner as the environmental samples. Precision of 

replicate results is calculated by the RPD (relative percentage difference) as defined by the difference (range) of each 

replicate sample set, divided by the average value (mean) of 

the set times 100. For replicate results, S1 and S2, the RPD is 

calculated from the following equation:

RPD = (S - S )/ (S +S )/2 100 { 1 2 1 2 }∗ ,

where

S1 is the concentration from the environmental 

sample; and

S2 is the concentration from the replicate sample.

Field replicates were collected at a frequency of 

10 percent or greater. Analyte concentrations from a total of 

21 nutrient, pesticide, and wastewater replicate samples were 

compared to concurrent environmental sample concentrations. Table 3 summarizes QA data for selected field blank and 

replicate sample constituent concentrations. Field blank concentrations were equal to or less than the minimum reporting 

limit (MRL) for all constituents, indicating little, if any, cross 

contamination. The maximum RPD for the replicate samples 

ranged from 1.9 to about 94 percent; the median RPD ranged 

from 0 to 4.2 percent. When comparing the small concentrations and slight differences between some replicate samples, 

the RPD can be relatively large, which is generally the case 

with the majority of replicate samples with a greater than 

10 percent RPD (Becher and others, 2001). 

Laboratory Quality Control

Spike and Blank Samples and Surrogate Compounds

Laboratory reagent spike (LRS) samples were used to 

yield information about method performance for organic 

analysis. An LRS is a sample solution to which known 

concentrations of the compounds of interest are added. The 

results are compared to acceptable criteria for each method to 

assess potential bias of environmental sample results (Pirkey 

and Glodt, 1998). In addition, laboratory reagent blank (LRB) 

samples were processed and analyzed in the same fashion as 

the environmental samples. The LRB matrix has negligible 

concentrations of compounds of interest and, as such, is 

used to monitor for laboratory processing contamination. If a 

compound of interest is detected in the blank sample, then the 

concentration of that same compound in the environmental 

sample can be qualified. A surrogate compound is a compound 

that is expected to perform similarly to the compounds being 

analyzed in a laboratory method (Pirkey and Glodt, 1998). 
8 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07 Table 3. Summary of analytical results for field blank and replicate samples for selected analytes, Meskwaki Settlement, central Iowa, water years 2006–07. [MRL, minimum reporting limit; mg/L, milligrams per liter; μg/L, micrograms per liter; N, nitrogen; P, phosphorus; RPD, relative percentage difference; <, less than; CIAT, 2-dichloro-4-isopropyl- amine-6-amino-S-triazine] Analyte (unit of measurement) MRL Number of blank samples Maximum concentration Median concentration Number of blank samples with concentrations greater than MRL Number of replicate samples Maximum RPD Median RPD Number of replicate samples with greater than 10 percent RPD Ammonia (mg/L as N) 0.02 5 <0.020 0.006 0 10 93.9 1.1 2 Nitrite (mg/L as N) .002 4 <.002 <.002 0 9 22.2 0 1 Nitrite plus nitrate (mg/L as N) .060 5 <.060 <.060 0 10 4.6 .8 0 Orthophosphate (mg/L as P) .006 4 <.01 <.006 0 9 1.9 .9 0 Acetochlor (μg/L) . 5 1 <.006 <.006 0 7 11.8 4.2 1 Atrazine (μg/L) . 5 1 <.007 <.007 0 7 2.2 1.6 0 CIAT (μg/L) . 5 1 <.014 <.014 0 7 20.9 11.8 2 Metolachlor (μg/L) . 5 1 <.010 <.010 0 7 4.3 1.7 0

1Based on estimated values.
Water-Quality Assessment 9

Surrogate compounds were added to all environmental and QC 

samples to monitor compound recovery and potential environmental effects. In this study, spike and blank samples and 

surrogate compounds were used in the analysis of all 93 environmental and QC samples. 

Water-Quality Assessment

Surface-Water Setting

The Meskwaki Settlement is drained by the Iowa River 

and its tributaries (fig. 1). The Iowa River enters the settlement along the southwestern boundary of the settlement near 

the town of Montour and forms much of the southern boundary before leaving along the settlement’s southeast boundary 

near Tama. The main tributaries are Onion and Cattail Creeks 

from the north and Raven and Bennett Creeks from the south. 

The headwaters of Onion Creek drain residential lands in the 

northern part of the settlement before flowing through areas 

used for limited commercial and agrarian purposes. Cattail 

Creek, which drains the main tribal residential and headquarters area along the eastern boundary, flows only during periods 

of intense or prolonged rainfall. Raven and Bennett Creeks 

drain extensive agricultural lands to the south before passing 

through sparse residential areas near the banks of the Iowa 

River. All tributaries enter a broad riparian buffer that borders 

the Iowa River in the settlement. 

Streamflow Data

Miscellaneous streamflow data were collected as conditions allowed at all water-quality sampling locations during 

times of sample collection (table 4). Measurements were made 

using a handheld acoustic Doppler velocimeter on tributaries 

and a trimaran acoustic data-collection platform on the Iowa 

River. Only one streamflow discharge measurement, at Iowa 

River near Montour (site 1), was not performed due to unsafe 

river ice in December 2006. Discharge for Cattail Creek 

(site 8) was estimated during two runoff periods in 2006. 

The nearest USGS-maintained gaging station (05451500) 

is located on the Iowa River in Marshalltown about 15 mi 

upstream from the settlement. Another Iowa River gage, 

operated by the U.S. Army Corps of Engineers (USACOE), 

is located along Highway 63 just south of Tama, about 1 mi 

east of the settlement (fig. 1). Both of these gaging stations are 

owned by the USACOE, and daily mean streamflow data are 

available on the USACOE Web site at http://www2.mvr.usace.

army.mil/nic2/default.cfm. 

Mean discharge for the Iowa River ranged from 

905 cubic feet per second (ft3/s) at site 1 near Montour to 

1,034 ft3/s at site 7 adjacent to the WRP (table 4). The minimum discharge recorded for the Iowa River was 354 ft3

/s at 

site 1 and the maximum discharge was 1,890 ft3/s at site 7. 

No discharge measurements were performed during storm 

flow but on the basis of data recorded at the Marshalltown 

(05451500) and Marengo (05453100) gaging stations (U.S. 

Geological Survey, 2007, 2008), discharge along the Iowa 

River in the settlement exceeded 6,000 ft3/s on five occasions 

during 2006–07 (fig. 2) and a maximum discharge of about 

14,000 ft3/s probably was reached in late April 2007. 

Measurements on Onion Creek ranged from less than 

0.01 ft3/s during July 2006 at site 2 to a maximum of 1.80 ft3/s 

during April 2006 at site 3. Mean discharge ranged from about 

0.5 ft3/s at site 2 to about 0.7 ft3/s at site 3. Discharge from 

sites 4 and 6 ranged from less than 1 ft3/s during August and 

September 2006 for Bennett Creek to 26.8 ft3/s during December 2006 for Raven Creek. Mean flow in Bennett Creek was 

about 3.5 ft3/s, whereas mean flow in Raven Creek was about 

15.4 ft3/s. 

Table 4. Statistical summary of surface-water discharge at Iowa River and tributary sampling sites within and contiguous to the 

Meskwaki Settlement, central Iowa, water years 2006–07.

[mi2, square miles; ft3/s, cubic feet per second; --, not available]

Site

number

(fig. 1)

Site name Drainage area

(mi2)

Minimum

discharge

(ft3/s)

Maximum

discharge

(ft3/s)

Mean

(ft3/s)

Number of

measurements 

or estimates

Type of 

measurements

1 Iowa River near Montour, Iowa 1,840 354 1,554 905 6 Periodic

2 Onion Creek below Highway 30 near 

Montour, Iowa

5.0 .004 1.72 .49 6 Periodic

3 Onion Creek near Montour, Iowa 5.3 .08 1.80 .66 7 Periodic

4 Raven Creek near Montour, Iowa 26.3 6.09 26.8 15.37 6 Periodic

5 Iowa River at Highway 49 near Tama, 

Iowa

1,882 371 1,830 1,031.9 7 Periodic

6 Bennett Creek near Tama, Iowa 7.0 .75 7.86 3.49 6 Periodic

7 Iowa River at WRP near Tama, Iowa 1,896 381 1,890 1,034.3 7 Periodic

8 Cattail Creek near Tama, Iowa 1.8 -- 13 -- 2 Stormflow only

1

 Estimated
10 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Water-Quality Data

Water-quality samples were collected at eight locations 

throughout the settlement (fig. 1). Samples were collected at 

approximately 5-week intervals between April and September 2006, followed by winter samples collected during late 

November and early December. Storm-flow samples were 

collected from all four tributaries by tribal technicians during 

August 2006 and again during November 2006 at Cattail 

Creek. In 2007, samples were collected in conjunction with 

habitat assessments conducted during June and July. Waterquality data for all sites are given in appendixes 1 through 8. 

Water-quality data are divided into seven categories of 

analytes and include physical properties, major ions, nutrients, 

trace metals, organic compounds, bacteria, and total suspended 

solids. Major constituents within each category are discussed 

as they relate to the quality of water defining baseline conditions. Where applicable, constituents are compared to the 

State of Iowa water-quality criteria for primary and secondary contact (Iowa Administrative Code, 2002). Changes in 

water chemistry and sediment concentration are explored as a 

function of water movement within the stream network of the 

settlement. 

The surface water in the Iowa River within and contiguous to the Meskwaki Settlement is classified according to the 

State of Iowa (Iowa Administrative Code, 2002) as Class A 

for primary contact recreation; Class B (WW) potential for 

wildlife, fish, aquatic and semi-aquatic life; and as HQR, or 

“high quality resource,” having substantial recreational or 

ecological significance. A set of criteria were established by 

the State of Iowa to protect these uses by assuring that waterquality levels are maintained or improved to meet the designated-use criterion. The criteria include levels of protection 

necessary to prevent chronic and acute toxicity to aquatic life 

and harmful effects to human health through consumption of 

fish (Iowa Administrative Code, 2002). Accordingly, chronic 

levels can be exceeded only in “mixing zones” (mathematically defined areas where wastewater or agricultural discharge mixes with stream water) or outside mixing zones for 

a brief time. Acute levels can be exceeded only at the “point 

of initial dilution” where the point source enters the stream 

(Iowa Administrative Code, 2002). A mathematical model for 

delineating dimensions of a mixing zone and zone of initial 

dilution can be found in “Supporting Document for Iowa 

Water Quality Management Plans” (Iowa Department of Natural Resources, 2000). A complete list of criteria for chemical 

constituents by use designations can be accessed on the Web at 

http://www.iowadnr.com/water/standards/files/chapter61.pdf. 

The physical, chemical, and biological compositions of 

surface water in the Iowa River and its tributaries are in a constant flux, both spatially and temporally, due to the dynamic 

relation between climate, streamflow, stream morphology, 

and land-use practices. Water quality, therefore, typically falls 

within a range of values for a specific body of water under a 

14,000

12,000

10,000

8,000

6,000

4,000

2,000

Apr. May June July Aug. Apr. May June July

2006 2007

Sept. Oct. Nov. Dec. Jan. Feb. Mar. Aug. Sept.

0

16,000

DISCHARGE, IN CUBIC FEET PER SECOND

Sampling site 1

Sampling site 5

Sampling site 7

Iowa River at Marengo, Iowa (05453100, fig. 1)

Iowa River at Marshalltown, Iowa (05451500, fig. 1)

Figure 2. Comparison of discharge measurements at streamflow gages upstream and downstream from sampling sites 1, 5, and 7 on 

the Iowa River at the Meskwaki Settlement, April 2006–September 2007.
Water-Quality Assessment 11

specific set of conditions. It is this range that defines the baseline conditions as discussed in the following sections. 

Physical Properties

Specific conductance, pH, water temperature, and dissolved oxygen concentrations did not indicate adverse waterquality conditions. Specific conductance is a measure of the 

ability of water to conduct an electrical current and varies as a 

function of the concentration of dissolved solids in the sample 

—the larger the concentration of dissolved solids, the larger 

the specific conductance. Smaller specific conductance values 

generally followed rainfall. Specific conductance for the Iowa 

River ranged from 391 to 782 microsiemens per centimeter 

(μS/cm) at 25 degrees Celsius (oC) with a median value of 

654 μS/cm, and from 289 to 703 μS/cm for the tributaries, 

with a median value of 548 μS/cm. In general, values were 

similar for all sites along the Iowa River on a specific day. 

Both the minimum and maximum values for the tributaries were recorded at Site 3 below the sewage lagoons. Water 

temperatures for all sites were typical for the times of the year 

that the sites were sampled. Temperatures ranged from a low 

of 0 oC in December to a high of 28 oC in July. The pH ranged 

from 7.7 to 8.9 standard units in the Iowa River and 7.2 to 

8.4 in the tributaries. The USEPA secondary drinking-water 

regulation (acceptable range) for pH is 6.5 to 8.5 (U.S. Environmental Protection Agency, 2007b). Biological and chemical 

processes are directly affected by the availability of dissolved 

oxygen in the water. Dissolved oxygen concentrations ranged 

from 6.8 to 22.7 milligrams per liter (mg/L) for the Iowa 

River, and 2.9 to 14.2 mg/L in the tributaries. The lowest 

value, 2.9 mg/L, was measured in Onion Creek due presumably to the effect of ground-water flow to the tributary or 

effluent from lagoons. The unusually high value of 22.7 mg/L, 

recorded on the Iowa River near Montour in July, 2007 was 

attributed to an observed algae bloom. 

Major Ions 

Water commonly is described by its major dissolved 

components, those chemical constituents that make up the bulk 

of inorganic dissolved solids in a sample of water. According to Hem (1985), they are defined as constituents generally 

present in concentrations exceeding 1.0 mg/L, whereby the 

predominant cation and anion concentrations, in milliequivalents per liter, define the water type. The dissolved cations 

that comprise a major part of the samples include calcium, 

magnesium, sodium, and potassium. Dissolved anions include 

sulfate, chloride, nitrate, and carbonate. Nitrate concentrations 

are discussed in more detail in the section on ”Nutrients.” 

Water Type

A trilinear diagram (Piper, 1944) illustrates the relative 

percentages of major cations and anions for all the samples 

collected during the study (fig. 3). The major-ion composition 

for each site was selected on the basis of the respective median 

concentration of dissolved solids. The diagram indicates that 

the majority of surface water sampled within the settlement 

was predominately a calcium bicarbonate type, which is the 

most common type of natural water found in Iowa. Major-ion 

data for the Iowa River, including Raven and Bennett Creeks 

from the south, plotted in a tight group. General clustering of 

data indicates sources of water that have potentially common 

processes affecting the water quality. Common processes 

would include surface-water runoff from similar land-surface 

areas with similar land-use practices and ground-water inflow 

containing natural or human inputs that might significantly 

alter the major-ion composition. Sites 2 and 3 on Onion Creek 

and site 8 on Cattail Creek, which plotted outside the group, 

represent urban effects in contrast with the Iowa River and 

Raven and Bennett Creeks, which largely represent agricultural effects. 

Dissolved Solids

Dissolved solids, also referred to as total dissolved solids 

(TDS) or total solids (Hem, 1985), is the residue on evaporation at a given temperature, in this case 105 oC, whereby the 

liquid is evaporated off and the remaining residue is weighed. 

Dissolved solids in surface water from the Meskwaki Settlement ranged from 182 to 492 mg/L (indicated as residue on 

evaporation at 180 degrees Celsius in the appendixes). As with 

specific conductance, smaller values in surface water generally 

followed rainfall. 

The State of Iowa is currently (2009) revising its interim 

2004 dissolved solids site-specific criteria in favor of a 

numerical chloride and sulfate criteria similar to that proposed 

by the Illinois Environmental Protection Agency (IEPA) 

for protection of aquatic life (Iowa Department of Natural 

Resources, 2007). Accordingly, research by the IEPA has 

shown that although other more toxic cations could occur in 

industrial waste, the relative concentrations of individual constituents, chloride and sulfate in this case, are more effective in 

determining toxicity than dissolved solids (Iowa Department 

of Natural Resources, 2007). The current interim dissolved 

solids toxicity level is 1,000 mg/L, above which acute toxicity 

tests would be required to show that facility discharge will not 

result in toxicity to aquatic life. 

Nutrients and Dissolved Organic Carbon

Nutrients, primarily nitrogen and phosphorus (as orthophosphate), are monitored in surface water because substantial 

amounts can result in excessive plant growth, such as algae, 

and reduction in dissolved oxygen. Nitrogen concentrations, in 

the bio-available form of nitrate, in excess of 3 mg/L generally are attributed to human activities (Madison and Brunett, 

1984), and large concentrations, primarily of phosphorus, have 

been linked to hypoxia in the Gulf of Mexico (Alexander and 

others, 2007). 
12 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

PERCENT

CALCIUM

 0 100 

 80 

 60 

 40 

 20 

 0 

 20 

 40 

 60 

 80 

 100 

MAGNESIUM

 0 

 20 

 40 

 60 

 80 

 100 

SODIUM PLUS POTASSIUM

CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

 0 

 20 

 40 

 60 

 80 

 100 

 100 

 80 

 60 

 40 

 20 

 0 

CARBONATE PLUS BICARBONATE

 100 

 80 

 60 

 40 

 20 

 0 

SULFATE

 0 

 20 

 40 

 60 

 80 

 100 

SULFATE PLUS CHLORIDE

 0 

 20 

 40 

 60 

 80 

 100 

CALCIUM PLUS MAGNESIUM

 100 

 80 

 60 

 40 

 20 

 0 

 100 

 80 

 60 

 40 

 20 

 0 

PERCENT

PERCENT

EXPLANATION

Iowa River and

southern tributaries

Northern

tributaries

Site 1

Site 2

Site 3

Site 4

Site 5

Site 6

Site 7

Site 8

Water sampling sites

Figure 3. Relative median compositions of surface water within and contiguous to the Meskwaki Settlement, central Iowa, water years 

2006–07.
Water-Quality Assessment 13

Nitrate (nitrate plus nitrite as nitrogen) concentrations, 

which constituted about 95 percent of the median total dissolved nitrogen, ranged from 1.85 to 14.2 mg/L in the Iowa 

River (sites 1, 5, and 7) with a median concentration of 

11.0 mg/L; 0.19 to 6.72 mg/L in Onion and Cattail Creeks 

(sites 2, 3, and 8) with a median concentration of 1.10 mg/L; 

and 2.56 to 13.4 mg/L in Raven and Bennett Creeks (sites 

4 and 6) with a median concentration of 7.50 mg/L (table 

5; fig. 4). About 62 percent of the nitrate samples collected 

from the Iowa River exceeded the USEPA MCL of 10 mg/L 

for drinking water as compared to 0 percent from Onion and 

Cattail Creeks and 43 percent from Raven and Bennett Creeks. 

Phosphorus in the form of orthophosphate ranged from 0.02 to 

5.74 mg/L, with a median concentration of 0.13 mg/L at all 

sites. The largest concentrations were in samples collected 

from Onion Creek downstream from the sewage lagoons 

(site 3) which had a median orthophosphate concentration of 

3.09 mg/L. 

Nutrient concentrations from the Iowa River (sites 1, 5, 

and 7) were compared with concentrations from the Wapsipinicon River near Tripoli, Iowa (table 6). The Wapsipinicon 

River near Tripoli (index map, fig. 1), a reference site for 

the USGS National Water-Quality Assessment (NAWQA) 

Program’s Eastern Iowa Watershed Assessment, was selected 

because of its similar land use and large percentage of streamcorridor wetlands as compared to other central Iowa drainage 

basins (Becher and others, 2001). Although maximum nitrate 

concentrations in the Iowa River were less than that for the 

Wapsipinicon River, the median concentrations indicate that, 

for the Iowa River, concentrations in excess of the MCL 

were more prolonged. The difference in ranges in total nitrate 

concentrations between the two rivers likely is attributed to 

the temporal extent of the respective datasets. Phosphorus 

(orthophosphate) concentrations were consistently larger in the 

Iowa River at all sites but for the single outlier of 0.29 mg/L in 

the Wapsipinicon River. 

Dissolved organic carbon (DOC) concentrations in 

natural water ranges from about 2 to 15 mg/L, with a median 

of about 5 mg/L (Degens, 1982). DOC in stream samples collected from the Meskwaki Settlement ranged from about 2.5 to 

56 mg/L (appendixes 1–8), with a median concentration of 

about 8.0 mg/L, which is consistent with concentrations of 5 to 

60 mg/L in water draining swamps and wetlands (Thurman, 

1985; Becher and others, 2001). The largest concentrations 

Table 5. Statistical summary of nutrient concentrations in water samples from the Iowa River and tributaries within and 

contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07, and comparison to water-quality guidelines.

[Location of sampling sites shown in figure 1; mg/L, milligrams per liter; MCL, Maximum Contaminant Level (U.S. Environmental Protection 

Agency’s primary drinking water regulations, 2007b); Min, minimum; Max, maximum; N, nitrogen; P, phosphorus; --, not applicable]

Nutrient

Minimum 

reporting level

(mg/L)

Concentration

MCL

(mg/L)

Number of 

samples 

exceeding 

MCL/number of 

samples

Min Max Median

Iowa River (sites 1, 5, and 7)

Ammonia, as N 0.05 0.002 0.067 0.008 -- --

Nitrate plus nitrite, as N .1 1.85 14.2 11.0 10 13/21

Nitrite, as N .02 .016 1.017 .021 1 1/20

Nitrogen, as N, total .06 2.32 15.3 12.5 -- --

Orthophosphate, as P .05 .059 .285 .13 -- --

Northern tributaries (sites 2, 3, and 8)

Ammonia, as N .05 .009 14.28 .036 -- --

Nitrate plus nitrite, as N .1 .19 6.72 1.10 10 0/16

Nitrite, as N .02 .003 .145 .022 1 0/15

Nitrogen, as N, total .06 .52 16.2 2.0 -- --

Orthophosphate, as P .05 .022 5.74 .401 -- --

Southern tributaries (sites 4 and 6)

Ammonia, as N .05 .003 .088 .026 -- --

Nitrate plus nitrite, as N .1 2.56 13.4 7.50 10 6/14

Nitrite, as N .02 .008 .07 .041 1 0/14

Nitrogen, as N, total .06 4.3 12.6 7.50 -- --

Orthophosphate, as P .05 .021 .18 .065 -- --
14 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

occurred in Raven Creek near Montour (site 4), which had a 

median concentration of 17.6 mg/L.

Trace Metals

Improvements in analytical equipment and methodologies are continually changing the ability to detect the minutest 

presence of trace metals in natural water. The term “trace” is 

used most often to refer to substances that commonly occur 

at concentrations less than 1 mg/L or 1,000 micrograms per 

liter (μg/L) (Hem, 1985). Technological advances in mass 

spectrometry have enhanced detection levels of 17 dissolved 

trace metals in the range from 1 to 0.001 mg/L (Faires, 1993; 

Fishman and Friedman, 1989). In addition, cold-vapor atomic 

fluorescence spectrometry was used to test for the presence of 

dissolved mercury (Garbarino and Damrau, 2001). 

Nine of the 18 trace metals analyzed in stream-water 

samples from the Meskwaki Settlement are on the USEPA’s 

list of metals assigned maximum contaminant levels (MCLs) 

for primary drinking water (U.S. Environmental Protection 

Agency, 2007b; table 7). They are antimony, arsenic, barium, 

beryllium, cadmium, chromium, mercury, selenium, and 

uranium. However, none of the samples analyzed had concentrations exceeding the respective MCLs or the State of 

Iowa criteria for chronic or acute toxicity (Iowa Administrative Code, 2002). Of the five analytes for which secondary 

MCLs (SMCL) exist (aluminum, copper, manganese, silver, 

and zinc), only manganese was found to exceed its respective SMCL of 50 mg/L (U.S. Environmental Protection 

Agency, 2007b). Manganese concentrations in the Iowa River 

ranged from 0.7 To 27 mg/L, with a median concentration of 

1.8 mg/L, whereas concentrations in water from the tributaries ranged from 3.9 to 1,060 mg/L, with a median value of 

56.3 mg/L. Seventeen of the 30 samples collected from the 

tributaries exceeded the SMCL, with about 65 percent of the 

exceedances coming from the Onion Creek sites. Large concentrations of soluble manganese may indicate anthropogenic 

input to the surface-water system (Hem, 1985), but it is 

unknown what the actual source(s) may be. 

Site 1 Site 2 Site 3 Site 4

SAMPLING SITES (fig. 1)

Site 5 Site 6 Site 7 

4

6

8

0

2

10

12

14

16

(A) Nitrate (nitrate plus nitrite) 

U.S. Environmental Protection Agengy (2007) 

Maximum Contaminant Level = 10 mg/L

CONCENTRATIONS, IN MILLIGRAMS PER LITER (mg/L)

Site 8

4

6

8

0

2

10

12

14

16

(B) Phosphorus (orthophosphate)

Figure 4. Concentrations of nitrate and phosphorus in surface water within and contiguous to the Meskwaki Settlement, central Iowa, 

water years 2006–07.
Water-Quality Assessment 15

Organic Compounds

In Iowa, as elsewhere in the Midwest, organic compounds such as pesticides are largely associated with use in 

the control of weeds and insects for agriculture. Compounds 

associated with non-agricultural uses commonly are found 

in pharmaceuticals, cosmetics, road and building materials, 

and automotive products, to name but a few. Whether entering the environment through direct application to crops, from 

landfills, sewage waste, fuel spills, or negligence, many of 

these compounds eventually end up contaminating rivers 

and streams generally as a result of surface runoff following intense or prolonged rainfall. To understand the extent to 

which these contaminants are present in waterways within the 

Meskwaki Settlement, surface-water samples were analyzed 

for the presence of pesticides, wastewater compounds, and 

fuel compounds. 

Pesticides

Laboratory analyses were conducted to determine the 

presence of pesticide contaminants in water samples collected 

from all eight sampling sites in the settlement (fig. 1). Samples 

were analyzed for 54 pesticide compounds that included 

herbicides and insecticides. Twelve of the 54 compounds had 

detectable concentrations among the 50 samples analyzed 

(table 8). Of those, 163 quantifiable detections were recorded 

in addition to 76 unquantifiable (estimated) detections. Atrazine had quantifiable detections in all 50 samples, metolachlor 

Table 6. Statistical summary of nutrient concentrations in water samples from the Iowa River at the Meskwaki Settlement, central 

Iowa, water years 2006–07, and the Wapsipinicon River near Tripoli, Iowa, water years 1996–2004.

[Location of sampling sites shown in figure 1; mg/L, milligrams per liter; N, nitrogen; P, phosphorus; WRP, Wetlands Reserve Property; <, less than; --, not 

applicable]

Constituent Number

of samples

Concentration, 

in milligrams per liter

Minimum 25th 

percentile Median 75th percentile Maximum

Iowa River near Montour, Iowa (site 1)

Ammonia (as N), dissolved 7 <0.010 <0.040 0.011 0.04 0.066

Nitrate plus nitrite (as N), dissolved 7 1.85 2.67 11.5 12.3 14

Nitrite (as N), dissolved 6 .016 .017 .024 .034 .035

Nitrogen (as N), total 6 2.36 5.74 12.3 13.38 15.1

Orthophosphate (as P), dissolved 6 .062 .082 .153 .198 .232

Iowa River at Highway 49 near Tama, Iowa (site 5)

Ammonia (as N), dissolved 7 <.010 <.020 .007 .017 .068

Nitrate plus nitrite (as N), dissolved 7 2.11 7.05 12.1 13.6 13.7

Nitrite (as N), dissolved 7 .016 .018 .018 .031 .04

Nitrogen (as N), total 7 2.6 7.49 12.6 14.5 15.3

Orthophosphate (as P), dissolved 7 .071 .097 .126 .214 .241

Iowa River at WRP near Tama, Iowa (site 7)

Ammonia (as N), dissolved 7 <.010 <.020 .007 .011 .065

Nitrate plus nitrite (as N), dissolved 7 2.09 7.05 12.3 13.7 14.2

Nitrite (as N), dissolved 7 .017 .018 .021 .03 .037

Nitrogen (as N), total 7 2.32 7.48 12.6 14.5 15.1

Orthophosphate (as P), dissolved 7 .059 .081 .14 .216 .23

Wapsipinicon River near Tripoli, Iowa (05420680)

Ammonia (as N), dissolved 76 -- 1.007 1.22 1.08 .88

Nitrate plus nitrite (as N), dissolved 76 .11 2.62 4.94 7.98 15

Nitrite (as N), dissolved 76 .006 .018 .035 .057 .146

Nitrogen (as N), total 9 .88 1.96 4 9.61 213.5

Orthophosphate (as P), dissolved 75 -- .01 .022 .05 .29

1

 Value is estimated by using a log-probability regression to estimate the values of data below the detection limit.

2

 Anomalous value is attributed to the small sample set for total nitrogen as compared to the other nitrogen species. 
16 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Table 7. Statistical summary of trace metal concentrations in water samples from the Iowa River and tributaries within and 

contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07, and comparison to water-quality guidelines.

[Location of sampling sites shown in figure 1; μg/L, micrograms per liter; MCL, Maximum Contaminant Level (U.S. Environmental Protection Agency’s 

primary drinking-water regulations, 2007b); SMCL, secondary Maximum Contaminant Level (U.S. Environmental Protection Agency’s secondary drinkingwater regulations, 2007b); E, estimated value; <, less than; --, no data]

Trace 

metal

Minimum 

reporting 

level

(mg/L)

Concentration (μg/L)

MCL

(μg/L)

SMCL

(μg/L)

State of Iowa criteria1 (μg/L) Number 

of 

Minimum Maximum Median samples

Chronic 

aquatic 

toxicity

Acute 

aquatic 

toxicity

Harmful to 

humans

Iowa River (sites 1, 5, and 7)

Aluminum 1.6 E1.4 17.2 3.0 -- 50 388 4,539 -- 21

Antimony .2 E.2 .3 .2 6 -- -- 21

Arsenic .12 1.4 2.6 2.1 10 -- 200 360 50 21

Barium .2 62.8 132 115 2,000 -- -- 21

Beryllium .06 <.06 <.06 <.06 4 -- -- 21

Cadmium .04 E.02 .05 <.04 5 -- 15 75 168 21

Chromium .04 .06 .4 .1 100 -- 40 60 3,365 21

Cobalt .04 .07 .39 .19 -- -- -- 21

Copper .04 .61 12.8 1.5 -- 1,000 35 60 1,000 21

Lead .08 E.04 1.24 .1 -- -- 30 200 -- 21

Manganese .2 .7 27 1.8 -- 50 -- 21

Mercury .01 <.01 <.01 <.01 2 -- 2.1 4 .15 3

Molybdenum .4 1.4 2.9 2 -- -- -- 21

Nickel .06 .73 5.21 1.58 -- -- 650 5,800 4,584 21

Selenium .08 1 2.3 1.8 50 -- 125 175 -- 21

Silver .2 <.2 <.2 <.2 -- 100 -- 100 -- 21

Uranium .04 1.72 4.81 3.75 30 -- -- 21

Zinc .06 E.4 52.1 1.8 -- 5,000 450 500 5,000 21

Northern tributaries (sites 2, 3 and 8)

Aluminum 1.6 2 23.8 5.4 -- 50 388 4,539 -- 16

Antimony .2 E.1 .9 .2 6 -- -- 16

Arsenic .12 1 4 1.8 10 -- 200 360 50 16

Barium .2 65.4 229 126 2,000 -- -- 16

Beryllium .06 <.06 <.06 <.06 4 -- -- 16

Cadmium .04 E.02 .14 <.04 5 -- 15 75 168 16

Chromium .04 E.07 3.2 .1 100 -- 40 60 3,365 16

Cobalt .04 .22 .87 .45 -- -- -- 16

Copper .04 .64 6.34 1.84 -- 1,000 35 60 1,000 16

Lead .08 E.04 .27 .1 -- -- 30 200 -- 16

Manganese .2 3.9 1,060 105 -- 50 -- 16

Mercury .01 -- -- -- 2 -- 2.1 4 .15 0

Molybdenum .4 1.2 56.3 2.8 -- -- -- 16

Nickel .06 1.55 5.75 2.76 -- -- 650 5,800 4,584 16

Selenium .08 .2 3.4 .4 50 -- 125 175 -- 16

Silver .2 <.2 <.2 <.2 -- 100 -- 100 -- 16

Uranium .04 .33 2.21 1.74 30 -- -- 16

Zinc .06 E.5 38.5 4.3 -- 5,000 450 500 5,000 16

Southern tributaries (sites 4 and 6)

Aluminum 1.6 1.7 16 3.6 -- 50 388 4,539 -- 14

Antimony .2 E.1 .5 .2 6 -- -- 14

Arsenic .12 .6 2.5 1.1 10 -- 200 360 50 14

Barium .2 109 156 144 2,000 -- -- 14

Beryllium .06 <.06 <.06 <.06 4 -- -- 14

Cadmium .04 E.02 .1 E.02 5 -- 15 75 168 14

Chromium .04 .09 1 .2 100 -- 40 60 3,365 14

Cobalt .04 .1 .4 .25 -- -- -- 14

Copper .04 E.34 7.79 1.84 -- 1,000 35 60 1,000 14

Lead .08 E.05 .75 <.08 -- -- 30 200 -- 14

Manganese .2 17.5 65.5 32.2 -- 50 -- 14

Mercury .01 -- -- -- 2 -- 2.1 4 .15 0

Molybdenum .4 .6 3.1 1 -- -- -- 14

Nickel .06 .83 5.58 2.08 -- -- 650 5,800 4,584 14

Selenium .08 1 2.7 1.8 50 -- 125 175 -- 14

Silver .2 <.2 <.2 <.2 -- 100 100 -- -- 14

Uranium .04 .76 1.72 1.33 30 -- -- 14

Zinc .06 E.3 14.1 .9 -- 5,000 450 500 5,000 14 1

 State of Iowa water-quality criteria (Iowa Administrative Code, 2002).
Water-Quality Assessment 17

in 48 of 50, acetochlor in 30 of 50, simazine in 14 of 50, and 

alachlor in 4 of 50 samples. Atrazine, simazine, and alachlor 

are on the USEPA’s list of contaminants for primary drinking water (U.S. Environmental Protection Agency, 2007b), 

but none were present in concentrations that exceeded their 

respective MCL (table 8; fig. 5). Chloripyrifos ranged in concentration from less than 0.005 to 0.010 mg/L and is the only 

pesticide analyzed that is regulated by the State. All samples 

from all sites contained one or more quantifiable detections of 

pesticides (table 9). Of the unquantifiable (estimated) detections, the triazine degradate ciat (2-chloro-4-isopropylamino6-amino-s-triazine) was found in all samples and accounted 

for about 66 percent of the detections (appendixes 1–8). 

Wastewater Compounds

Laboratory analyses were conducted to determine the 

presence and concentration of wastewater contaminants in 

water samples collected from sites 2 and 3 on Onion Creek, 

upstream and downstream from the Meskwaki sewage-lagoon 

outflow, respectively; Cattail Creek downstream from the 

tribal headquarters and central housing complex; and the 

three sites along the Iowa River (fig. 1). Analyses included 

67 compounds consisting of pesticides, fragrance (HHCB), 

insect repellant (DEET), and petroleum derivatives (polycyclic aromatic hydrocarbons; PAHs). Pesticide compounds and 

PAHs usually are not found in sewage effluent and most likely 

represent transport due to surface runoff. Thirty-six of the 

67 wastewater compounds were detected among 36 samples 

analyzed. Of that, nine quantifiable detections were recorded 

(table 10) in addition to 217 unquantifiable detections (appendixes 1–8). Six of the nine quantifiable detections were from 

Onion Creek site 3 and included four occurrences of HHCB 

and one each of caffeine and DEET. In comparison, site 2 

had no quantifiable detections of any compound and about 

9 percent of the total number of detections, or about 75 percent fewer total detections than site 3 (table 11). DEET also 

was detected in a sample from the Iowa River near Montour (site 1). A single detection of the pesticide metolachlor 

was found in a sample from the Iowa River at the Wetlands 

Reserve Property (WRP). Of the unquantifiable detections, 

caffeine, the fragrance derivatives (HHCB and AHTN), and 

insect repellent (DEET) accounted for approximately 50 percent of the 36 compounds. PAHs accounted for approximately 

22 percent of the 36 compounds, and metolachlor accounted 

for about 11 percent. Most of the PAH detections occurred following runoff. All but 4 of the 24 unquantifiable detections of 

metolachlor were from the Iowa River. Only phenol, of which 

there were three unquantifiable detections, is regulated by the 

State1; estimated concentrations ranged 0.008 to 0.172 μg/L. 

________________ 1 State regulations for class B(WW) water are 50, 2,500 and 300 mg/L 

for chronic and acute toxicity for aquatic life and human health levels, 

respectively.

Table 8. Analytical results for selected pesticides in water samples from the Iowa River and tributaries within and contiguous to the 

Meskwaki Settlement, central Iowa, water years 2006–07, and comparison to water-quality guidelines.

[μg/L, micrograms per liter; MCL, Maximum Contaminant Level (U.S. Environmental Protection Agency’s primary drinking-water regulations, 2007b; 

HAL, health advisory level, (U.S. Environmental protection Agency, 1996); E, estimated; <, less than; --, not applicable]

Pesticide

Minimum 

reporting 

level

(μg/L)

Range in 

concentration

(μg/L)

Median

(μg/L)

MCL

(μg/L)

HAL

(μg/L)

State of Iowa criteria (μg/L) Number of 

detections/

number of 

samples

Chronic 

aquatic 

toxicity

Acute 

aquatic 

toxicity

Harmful to 

humans

Acetochlor 0.006 E0.003 to 0.091 0.040 -- -- -- -- -- 35/50

Alachlor .005 <.005 to .01 <.005 2 -- -- -- -- 4/50

Atrazine .005 .028 to 1.10 .107 3 -- -- -- -- 50/50

Carbaryl .041 E.003 to E.035 E.017 -- -- -- -- -- 5/50

Chlorpyrifos .005 E.004 to .010 <.005 -- -- 0.041 0.083 -- 5/50

CIAT (2-chloro4-isoproplyamino-6-aminos-triazine) .050 E.013 to E.127 E.049 -- -- -- -- -- 50/50

Cyanazine .005 <.018 to .067 <.018 -- 1 -- -- -- 1/50

Dacthal .003 E.001 to .005 <.003 -- -- -- -- -- 8/50

Malathion .027 <.016 to .318 <.027 -- -- -- -- -- 2/50

Metolachlor .005 E.008 to 1.45 .045 -- 70 -- -- -- 48/50

Prometon .010 E.004 to .064 <.010 -- 100 -- -- -- 14/50

Simazine .018 E.003 to .609 <.005 4 -- -- -- -- 17/50
18 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Site 1 Site 2 Site 3 Site 4

SAMPLING SITES (fig. 1) 

Site 5 Site 6 Site 7 

0.25

0.50

0.75

0

1.0

1.25

1.50

(B) Atrazine 

CONCENTRATIONS, IN MICROGRAMS PER LITER (μg/L)

Site 8

0.25

0.50

0.75

0

1.0

1.25

1.50

(A) Alachlor

Maximum Contaminant Level = 2 μg/L Maximum Contaminant Level from 

U.S. Environmental Protection 

Agency (2007)

Maximum Contaminant Level = 3 μg/L

0.25

0.50

0.75

0

1.0

1.25

1.50

(C) Simazine

Maximum Contaminant Level = 4 μg/L

Figure 5. Concentrations of selected pesticides in surface water within and contiguous to the Meskwaki Settlement, central Iowa, 

water years 2006–07.
Water-Quality Assessment 19

Table 9. Frequency of quantifiable pesticide detections in water samples from the Iowa River and tributaries within and contiguous 

to the Meskwaki Settlement, central Iowa, water years 2006–07. 

[Pesticide compounds listed in order of decreasing detection frequency. mg/L, micrograms per liter; --, not applicable]

Pesticide

compound

Percentage of 

samples with

 detections

 Number of

samples

Maximum

concentration

(μg/L)

Minimum

reporting limit

(μg/L)

Action/use1

Any compound 100 50 1.45 -- --

Atrazine 100 50 1.10 0.005 Selective herbicide/corn, sorghum

Metolachlor 92.0 50 1.45 .005 Selective herbicide/corn, sorghum, pasture 

Acetochlor 60.0 50 .091 .006 Selective herbicide/corn, soybeans

Simazine 28.0 50 .609 .018 Selective herbicide/corn

Prometon 16.0 50 .064 .010 Nonselective herbicide

Dacthal 10.0 50 .005 .003 Herbicide metabolite 

Chlorpyrifos 6.0 50 .010 .005 Insecticide/corn, soybeans

Alachlor 8.0 50 .010 .005 Preemergent herbicide/corn, soybeans

Malathion 3.9 50 .318 .027 Nonselective insecticide 

Cyanazine 2.0 50 .067 .005 Selective herbicide/corn

1

Modified from Kolpin and others (1993).

Table 10. Frequency of quantifiable wastewater compound detections in water samples from the Iowa River and tributaries within 

and contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07. 

[Wastewater compounds listed in order of decreasing detection frequency. μg/L, micrograms per liter; --, not applicable]

Wastewater

compound

Percentage of 

samples with

detections

Number of

samples

Maximum

concentration

(mg/L)

Reporting

limit

(mg/L)

Action/use1

Any compound 25.0 36 1.33 -- --

HHCB 8.3 36 .598 0.5 Fragrance/personal care products

N,N-diethyltoluamide (DEET) 5.6 36 1.33 .5 Insect repellant

Caffeine 2.8 36 1.11 .5 Stimulant/coffee, soft drinks, medicine

Carbaryl 2.8 36 .25 .041 Contact insecticide

Metolachlor 2.8 36 .169 .16 Selective herbicide/corn, sorghum, pasture 

Indole 2.8 36 1.09 .5 Chemical reagent/perfumery, medicine; 

flavoring agent

1

Modified from Kolpin and others (1993).
20 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Fuel Compounds

Tests were conducted to determine the presence of fuel 

compounds in water samples collected from sites 1–3, 5, 7, 

and 8 (fig. 1) and included benzene, ethylbenzene, tert-butyl 

methyl ether (MTBE), toluene, and xylene. Of the 34 samples 

collected, the only detections that occurred were for toluene in 

the Iowa River near Montour (site 1) and at Highway 49 near 

Tama (site 5). Both sample concentrations were at the reporting limit of 0.1 μg/L and may have resulted from motorcraft 

discharge at the time of sampling. Due to their volatility in 

contact with the atmosphere, fuel compounds are not commonly detected in Iowa streams under normal circumstances 

(S.J. Kalkhoff, U.S. Geological Survey, oral commun, 2007). 

Bacteria

Bacteria samples were collected at all sites during this 

study and included E. coli and fecal coliform. E. coli is a type 

of fecal bacteria that comes from human and animal wastes 

that may be washed into waterways during periods of rainfall or snowmelt runoff. Fecal coliform is used to indicate 

the potential presence of harmful bacteria in water supplies. 

For surface water designated as Class “A,” primary contact 

recreation, the State of Iowa’s sample maximum E. coli

content has been set at 235 colony forming units per 100 milliliters (cfu/100 mL) from March 15 through November 15, 

except when affected by surface runoff (Iowa Administrative 

Code, 2006). 

Between April and October 2006 and 2007, E. coli densities in samples from the Iowa River within and contiguous 

to the settlement ranged from less than 10 to 1,600 cfu/100 

mL with a median value of about 160 cfu/100 mL (table 

12; fig. 6). In general, densities over 200 cfu/100 mL were 

storm-flow related. E. coli densities in tributaries north of 

the Iowa River ranged from 73 to 880 cfu/100 mL in Onion 

Creek at the upstream site 2, and from 130 to 440,000 cfu/100 

mL downstream from the sewage lagoons (site 3). A density 

of 440,000 cfu/100 mL, in a storm-flow sample collected in 

August 2006, was likely the result of overflow from the sewage lagoons just upstream from sampling site 3. Densities in 

two storm-flow samples from Cattail Creek were 1,700 and 

610,000 cfu/100 mL. The unusually large bacterial density 

was reportedly due to raw sewage from a local residential 

septic system (K. Schott, Meskwaki Natural Resources 

Department, oral commun., 2006). E. coli densities measured 

south of the Iowa River in samples from Raven and Bennett 

Creeks ranged from 1,100 to 23,000 cfu/100 mL and 270 to 

33,000 cfu/100 mL, respectively. 

E. coli densities in samples from the Iowa River and its 

tributaries within and contiguous to the Meskwaki Settlement 

were either equal to or less than the respective densities for 

fecal coliform in the same samples (fig. 6). 

Total Suspended Solids

Median total suspended solids (TSS) concentrations 

ranged from less than or equal to about 20 mg/L at sampling 

sites 2, 3, and 6 on Onion and Bennett Creeks to more than 

150 mg/L at site 8 on Cattail Creek (fig. 7). Water with TSS 

concentrations less than about 20 mg/L generally is considered 

to be relatively clear, whereas water with TSS concentrations 

more than about 150 mg/L is considered dirty (Michigan 

Department of Environmental Quality, 2008). Median TSS 

concentrations for water from sites 1, 5, and 7 on the Iowa 

River and site 4 at Raven Creek fall within the cloudy or 

murky range. In this regard, TSS provides an indication of 

median water-quality conditions in relation to turbidity for the 

Meskwaki Settlement. 

TSS originally was developed for the analysis of 

wastewater samples but has become a common measure in 

the analysis of natural water as a surrogate for suspendedsediment concentration. However, a recent study has shown 

that TSS values provide, at best, an estimation of suspended 

sediment only when the sand fraction of a suspended-sediment 

sample is less than about 25 percent of the dry sediment mass 

(Gray and others, 2000). In general, although TSS is a fair 

approximation of suspended-sediment concentration at base 

flow, it should not be used for computing sediment load other 

than during base-flow conditions. 

Sediment-Quality Data

Streambed sediment samples were collected in conjunction with the biological assessments from the three sampling 

sites along the Iowa River (sites 1, 5, and 7) and from Onion 

Table 11. Relations between quantifiable and unquantifiable 

wastewater compound detections in water samples from the 

Iowa River and tributaries within and contiguous to the Meskwaki 

Settlement, central Iowa, water years 2006–07. 

Site 

number Site name

Quantifiable 

detections

Unquantifiable 

detections

Total 

detections

Relative

percentage of 

detections

1 Iowa River near 

Montour, IA

1 28 29 12.8

2 Onion Creek below 

Highway 30 near 

Montour, IA

0 20 20 8.9

3 Onion Creek near 

Montour, IA

6 82 88 38.9

5 Iowa River at 

Highway 49 near 

Tama, IA

1 35 36 15.9

7 Iowa River near 

Tama, IA

1 34 35 15.5

8 Cattail Creek near 

Tama, IA

0 18 18 8.0
Water-Quality Assessment 21

DENSITIES, IN COLONY FORMING UNITS PER 100 MILLILITERS

10,000

0

30,000

40,000

20,000

440,000

450,000

430,000

610,000

620,000

600,000

(B) Fecal coliform

SAMPLING SITES (fig. 1)

Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8

(A) Escherichia coli

10,000

0

30,000

40,000

20,000

440,000

450,000

430,000

610,000

620,000

600,000

Figure 6. Bacteria densities in surface water within and contiguous to the Meskwaki Settlement, central Iowa, between April and 

October, water years 2006–07.
22 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Creek downstream from the sewage lagoons (site 3). Because 

aquatic species often feed off nutrients attached to streambed 

sediment, in-situ or in suspension, they are susceptible to 

ingesting chemicals and metals adsorbed to the granular surfaces. Toxic concentrations for some species may be attained 

over time through bioaccumulation. The Florida Department 

of Environmental Protection developed a set of effects-based 

guidelines for its coastal waters through a statistical comparison of chemical concentrations associated with biological 

effects to concentrations associated with no observed effects 

(U.S. Environmental Protection Agency, 2004a). Adopted by 

the USEPA, the “threshold effects level” (TEL) represents 

the concentrations below which toxic biological effects rarely 

occur, the “probable effects level” (PEL) represents the concentrations above which toxic effects usually occur, and values 

ranging between the TEL and PEL represent those concentrations where toxic effects occasionally occur. The TEL and PEL 

guidelines can be used as a screening tool because the effectscorrelation procedure does not demonstrate that a particular 

contaminant is solely responsible for an adverse organism 

response (Schnoebelen and others, 2003; U.S. Environmental 

Protection Agency, 2004a). 

Trace Metals and Organic Compounds

No trace metal concentrations were found in sediment 

from the Iowa River that exceeded either the TEL or PEL 

guidelines (table 13). However, arsenic and nickel concentrations of 13.4 and 19 micrograms per gram (mg/g) were 

found in a composite sample from Onion Creek (site 3) 

that exceeded the TEL of 7.24 and 15.9 mg/g, respectively. 

The source of the metals is unknown. Also, it is unknown if 

any silver concentrations exceeded the TEL of 0.733 mg/g 

because the minimum reporting level for silver is 1.0 mg/g. 

Tests for organic compounds sorbed to sediment included 

108 compounds. None of the samples were found to contain organic compounds exceeding the respective minimum 

reporting limits. 

Biological Assessment

During the summer of 2007, biological data were collected at the Meskwaki Settlement. Three sites on the Iowa 

River—Iowa River near Montour (site 1), Iowa River at 

County Road E49 near Tama (site 5), and Iowa River at 

Wetlands Reserve Property near Tama (site 7), and one site 

0

10

20

30

-10

-20

MEDIAN TURBIDITY, IN NEPHELOMETRIC TURBIDITY UNITS

MEDIAN TOTAL SUSPENDED SOLIDS CONCENTRATIONS, IN MILLIGRAMS PER LITER (mg/L)

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

WATER APPEARS CLOUDY OR MURKY

WATER APPEARS CLEAR

 curve = -106.9654 + 133.2082*log x 

WATER APPEARS DIRTY

(~150 mg/L)

(~20 mg/L)

Site 1

Site 2

Site 3

Site 4

Site 5

Site 6

Site 7

Site 8

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

Figure 7. Concentrations of median total suspended solids compared to median turbidity in surface water 

within and contiguous to the Meskwaki Settlement, central Iowa, water years 2006–07.
Biological Assessment 23

on Onion Creek—Onion Creek near Montour (site 3)—were 

sampled. These sites were sampled to provide a baseline 

assessment of aquatic biological conditions. The biological 

samples collected included fish community, benthic macroinvertebrates, and periphyton samples, as well as physicalhabitat measurements. In addition, fish-tissue samples were 

collected at these four sites. Where available, Indexes of 

Biological Integrity (IBI) were used to assess the overall 

condition of the specific biotic communities. A benefit of using 

an IBI is to provide a translation of an ecologist’s assessment 

of the biological community into a value that will make sense 

to persons unfamiliar with ecological communities (Hughes 

and others, 1998). An IBI consists of a series of biotic community attributes, termed metrics, which reflect basic structural 

characteristics of biotic assemblages (Lyons, 1992). Each individual metric is rated and that rating is based on quantitative 

expectations of what is considered excellent biotic integrity. 

The sites within the Meskwaki Settlement were separated 

into large river and wadeable sites. The three sites on the Iowa 

River are considered large river sites, and Onion Creek is considered a wadeable site. This separation is important to know 

because the choice of indexes used has been based upon drainage area of the sampling site. Wadeable streams are considered 

to have drainage areas of less than 1,000 square miles (mi2), 

and large river sites are considered to fall in the range from 

1,000 mi2 and 2,300 mi2 (Simon, 2007). 

There are few large river indexes in use today. Reasons 

for this may include that within large rivers systems there is 

increased difficulty in accurately sampling the different biotic 

assemblages, and few quality reference sites are available 

to develop expectations of metric values (Davis and Simon, 

1995). 

Fish Community 

The Iowa Department of Natural Resources (IDNR) 

has developed a Fish Index of Biological Integrity (FIBI) for 

wadeable streams (Wilton, 2004). The Iowa FIBI classifies 

the biological condition of the fish population in a six-tiered 

approach (fig. 8). This approach is endorsed by the USEPA 

as a tool to evaluate the biological condition of a water body 

(U.S. Environmental Protection Agency, 2005). A tiered 

approach provides resource managers with a tool that will 

help develop and refine water-quality management practices. 

On a basis of this approach, tiers 3 and 4 reflect the biological condition in most Iowa rivers and streams (Wilton, 2004: 

fig. 8). For the purpose of comparison, the Iowa FIBI was used 

for all of the sites sampled in this study, although the drainage areas for the three Iowa River sampling sites within the 

Meskwaki Settlement are 1,840 mi2 (site 1), 1,882 mi2 (site 5), 

and 1,896 mi2 (site 7; appendix 9). 

Excellent

(71−100)

Good

(51−70)

Fair

(26−50)

Poor

(0−25)

1 Native or natural conditions

2 Minimal loss of species;

 some density changes may occur

3

Some replacement of

sensitive rare species;

functions fully maintained

4

Some sensitive species maintained,

but notable replacement by more

tolerant taxa; altered distributions;

functions largely maintained

6 Severe alteration of

structure and function

5

Tolerant species show increasing

dominance; sensitive species are

rare; functions are altered

100

125

0

25

50

75

Low

HUMAN DISTURBANCE GRADIENT

High

 IOWA FISH INDEX OF BIOTIC INTEGRITY RATING (SCORING RANGE)

NOT TO SCALE

Figure 8. Fish Index of 

Biological Integrity (FIBI) 

qualitative scoring ranges in 

relation to a conceptual tiered 

(1–6) human disturbance 

gradient.
24 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

Drainage area is important to note because it is a factor in 

the calculation of several of the metrics within the FIBI. Due 

to the concern that the Iowa index was developed for wadeable 

sites, an index developed for large rivers by the Ohio Environmental Protection Agency (Ohio EPA), (Ohio Environmental 

Protection Agency, 1987) was used in an attempt to validate 

the Iowa wadeable site index results. The individual metrics 

used for each particular index can be found in Wilton (2004). 

The results calculated by the two indexes are described in 

table 14. 

 On the basis of the Iowa FIBI, all of the sampling sites 

have calculated indexes indicating a fair classification except 

for the Iowa River at Highway 49 near Tama (site 5). This 

site was classified just below fair by a value of 1.1, which is 

about 5.4 percent of the range of results for all of the sites 

combined. Possible reasons for this FIBI score could be 

attributed to the fact that the sampling at this site was difficult, 

and a small number of fish were obtained. Difficult conditions at site 5 were due to the large abundance of woody snags 

and trees. These snags and trees made for hazardous conditions during boat operation as well as obstacles for netters 

which lead to missed fish. Due to the small number of fish 

obtained, an adjustment, as discussed in Wilton (2004), was 

needed to account for the small number, which led to a lower 

index score. 

The FIBI score for the Iowa River sites was calculated 

using the IDNR FIBI. The ungaged IDNR reference site North 

Skunk River near Rosehill, in southeastern Iowa (fig. 1) was 

used as a comparison. This site was selected because it had 

the closest drainage area (529 mi2) to the Iowa River sites as 

well as being located in the same level IV ecoregion (47f) as 

described by Chapman and others (2002). The North Skunk 

River had an FIBI score of 36, which would be classified as 

fair (Wilton, 2004). This fair classification is consistent with 

the fair classification values outlined in table 14 as determined 

for the Iowa River sites within the Meskwaki Settlement. 

Also, the FIBI score for the wadeable site Onion Creek 

near Montour, Iowa (site 3), was calculated using the IDNR 

FIBI. The IDNR reference site at Richland Creek near Haven 

(05451900) in central Iowa (fig. 1) was used for comparison. 

The reasons for selecting this site were based on similar drainage areas (56 mi2

 for Richland Creek) as well as being located 

within the same level IV ecoregion (47f). Richland Creek 

near Haven (05451900) had an index score of 42 (Wilton, 

2004), which also would be classified as fair. This classification is consistent with the fair classification of 45 that was 

calculated for Onion Creek (table 14). The consistency of IBI 

scores between the Richland Creek reference site (05451900) 

and Onion Creek (site 3) could be attributed to the conditions during the sampling period at Onion Creek. Increased 

flow during the time of fish sampling at Onion Creek would 

have provided additional habitat for fish species that typically would not inhabit the reach during base-flow conditions. 

This increased habitat availability due to the higher flows in 

Onion Creek may have triggered fish from the Iowa River into 

moving upstream into Onion Creek, which resulted in a higher 

FIBI score. The use of the Ohio EPA index was not applicable 

because this site is considered wadeable, and the Iowa FIBI is 

considered valid for this stream. 

In an attempt to validate the findings of the IDNR FIBI, 

an alternative FIBI was determined to be useful. The Ohio 

EPA method was used by the USGS NAWQA program (Sullivan, 2000) to assess six sites sampled by the USGS in 1996. 

Of these six sites, two of them were on the Iowa River, and 

one was the Iowa River at Marengo (05453100, fig. 1), which 

is just 48 river miles downstream from the most downstream 

site sampled within the Meskwaki Settlement during 2007. 

When calculating an index value using the Ohio EPA method 

for the Iowa River sites within the Meskwaki Settlement, 

Table 12. Statistical summary of escherichia coli (E. coli) densities at selected sampling sites along the Iowa River and tributaries 

within and contiguous to the Meskwaki Settlement, central Iowa, between April and October, water years 2006–07.

[cfu/100 mL, colony forming units per 100 milliliters; Min, minimum; Max, maximum; <, less than; WRP, Wetlands Reserve Property; --, not applicable]

Site 

number Site name

E. coli

(cfu/100mL)

Min Max Median

Number

of

samples

Number of samples

exceeding

235 cfu/100 mL

1 Iowa River near Montour, IA 10 1,600 160 6 3

2 Onion Creek below Highway 30 near Montour, IA 73 880 150 6 2

3 Onion Creek near Montour, IA 130 440,000 330 8 7

4 Raven Creek near Montour, IA 1,100 23,000 6,750 6 6

5 Iowa River at Highway 49 near Tama, IA <10 900 175 6 2

6 Bennett Creek near Tama, IA 270 33,000 3,200 6 6

7 Iowa River at WRP near Tama, IA 30 450 155 6 2

8 Cattail Creek near Tama, IA 1,700 610,000 -- 2 2
Biological Assessment 25

Table 13. Statistical summary of selected trace metals in streambed-sediment samples from the Iowa River in comparison to 

samples from Onion Creek, Meskwaki Settlement, central Iowa, August 2007.

[mg/g, Min, minimum; Max, maximum; micrograms per gram; TEL, threshold effects level; PEL, probable effects level; --, not applicable; bold value, 

exceeds U.S. Environmental Protection Agency’s (2004a) sediment-quality guideline; <, less than]

Trace metal

Concentrations in streambed-sediment samples (μg/g) Iowa River 

(sites 1, 5, and 7) Onion Creek 

(site 3)

Sediment-quality guidelines1

(μg/g)

Min Max Median Mean TEL PEL

Aluminum 36,800 39,200 36,900 37,630 30,600 -- --

Antimony .1 .1 .1 .1 .41 -- --

Arsenic 2.3 2.9 2.8 2.7 13.4 7.24 41.6

Barium 487 525 497 503 731 -- --

Beryllium .75 .82 .76 .78 .87 -- --

Bismuth <.06 <.06 <.06 <.06 .06 -- --

Cadmium .06 .09 .07 .07 .32 .676 4.21

Cerium 18.3 23.1 20.7 20.7 46.4 -- --

Cesium .50 .55 .52 .52 .98 -- --

Chromium 10.5 14.1 14.1 12.9 17.8 52.3 160

Cobalt 4.8 5.4 5.2 5.1 17.1 -- --

Copper <2 <2 <2 <2 <2 18.7 108

Gallium 7.6 7.9 7.7 7.7 6.7 -- --

Iron 7,580 8,870 7,830 8,093 17,600 -- --

Lanthanum 9.0 11.3 10.0 10.1 16.1 -- --

Lead 8.54 8.83 8.55 8.6 16.8 30.2 112

Lithium 1.6 2.7 2.4 2.2 4.2 -- --

Manganese 597 609 601 602 2,980 -- --

Mercury <.01 <.01 <.01 <.01 <.01 .13 .696

Molybdenum .1 .1 .1 .1 1 -- --

Nickel 8.3 8.9 8.4 8.5 19 15.9 42.8

Niobium 1.8 3.2 1.9 2.3 3.8 -- --

Phosphorus 216 347 237 267 759 -- --

Rubidium 37.6 41.4 39.5 40.0 39.0 -- --

Scandium 1.6 2.3 2.0 2.0 2.7 -- --

Selenium .1 .1 .1 .1 .2 -- --

Silver <1 <1 <1 <1 <1 .733 1.77

Strontium 202 218 209 210 138 -- --

Thallium .24 .26 .24 .25 .29 -- --

Thorium 1.90 2.36 2.04 2.10 3.11 -- --

Titanium 477 845 530 617 923 -- --

Uranium .49 .57 .57 .54 .92 -- --

Vanadium 13.8 18.8 14.5 15.7 37.7 -- --

Yttrium 5.4 6.7 5.7 5.9 11.1 -- --

Zinc 14.3 17 14.5 15 33 124 271
26 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

a classification of fair was determined for all three sites 

(table 14). This determination of fair is consistent with the 

IDNR FIBI scores. The fair classification of the Meskwaki 

Iowa River sites illustrates an increased level of quality 

compared to the sites previously mentioned in the Sullivan 

report. The Iowa River at Marengo had a score of 22 which 

is considered poor using the Ohio EPA large river index. The 

time frame for the collection of the Iowa River at Marengo 

data could likely be the reason for the classification of poor. 

Benthic Macroinvertebrate Community 

The IDNR also has developed a Benthic Macroinvertebrate Index of Biological Integrity (BMIBI) for wadeable 

streams (Wilton, 2004). The BMIBI classifies the biological 

condition of the invertebrate population in a tiered approach 

similar to the FIBI (fig. 9). This approach is endorsed by the 

USEPA as a tool to evaluate the biological condition of a water 

body. A tiered approach provides resource managers with a 

tool that will help develop and refine water-quality management practices. 

On the basis of this approach, tiers 3 and 4 reflect the biological condition in most of Iowa’s rivers and streams (Wilton, 

2004). Within tiers 3 and 4, the expected classifications using 

the BMIBI include excellent, good, and fair (fig. 9). The index 

includes 12 individual metrics. For the purpose of comparison, 

this index was used for all of the sites sampled in this study, 

although the drainage areas for the Iowa River sites within 

the Meskwaki Settlement varied from 1,840 to 1,896 mi2. The 

results calculated by this index are described in table 15. All 

of the Iowa River sites within the Meskwaki Settlement have 

calculated index scores indicating a good classification except 

for the Iowa River near Montour (site 1) which was classified 

as fair.

The Iowa River sites were compared to the North Skunk 

River near Rosehill, Iowa, using the BMIBI scores. The North 

Skunk River near Rosehill is considered a reference site for 

the IDNR within ecoregion 47f. This site was selected for the 

same reasons as it was for the FIBI because it had a drainage 

area similar in size to the Iowa River sites as well as being 

located in the same level IV ecoregion (47f), as described by 

Chapman and others (2002). The North Skunk River site had a 

BMIBI score of 53 (Wilton, 2004), which would be classified 

as fair. The fair classification from the North Skunk River is 

Excellent

(76−100)

Good

(56−75)

Fair

(31−55)

Poor

(0–30)

1 Native or natural conditions

2 Minimal loss of species;

 some density changes may occur

3

Some replacement of

sensitive rare species;

functions fully maintained

4

Some sensitive species maintained

but notable replacement by more

tolerant taxa; altered distributions;

functions largely maintained

6 Severe alteration of

structure and function

5

Tolerant species show increasing

dominance; sensitive species are

rare; functions are altered

100

125

0

25

50

75

Degraded

Natural

Low

HUMAN DISTURBANCE GRADIENT High

IOWA BENTHIC MACROINVERTEBRATE INDEX OF BIOTIC INTEGRITY RATING (SCORING RANGE)

NOT TO SCALE

Figure 9. Benthic Marcoinvertebrate Index of Biological Integrity (BMIBI) qualitative scoring ranges in 

relation to a conceptual tiered (1–6) human disturbance gradient.
Biological Assessment 27

less favorable than the good classification that was determined 

for two of the Iowa River sites within Meskwaki Settlement. 

Also, the BMIBI score for the wadeable site Onion Creek 

near Montour (site 3) was calculated using the IDNR reference site at Richland Creek near Haven, Iowa, as a comparison. The reasons for selecting this site were based on similar 

drainage areas as well as being located within the same level 

IV ecoregion (47f). Richland Creek near Haven had a BMIBI 

index score of 64 (Wilton, 2004) which would indicate a good 

classification. This classification is consistent with the good 

classification (BMIBI index score of 60.6) that was calculated 

for Onion Creek (site 3). The consistent score between Onion 

Creek and the reference stream is indicative of the quality 

invertebrate habitat available in Onion Creek at the time sampling took place. 

Periphyton (Algae) 

The USEPA assessment data for 2004 for the State of 

Iowa indicates that of the 7,830 mi of rivers and streams 

sampled in Iowa, 76.2 percent were either impaired or 

threatened. Nutrient contamination was among the top 10 

causes of impairment in Iowa rivers and streams (U.S. Environmental Protection Agency, 2004b). Nutrient enrichment can 

be detected through water sampling with chemical analysis 

for nitrogen, phosphorus, and their transformation products as 

well as periphyton (benthic algae) and phytoplankton (algae 

in suspension) sampling and analysis. For the ecological part 

of the study that took place at the sites within the Meskwaki 

Settlement, periphyton samples were collected to assess the 

condition of the water. 

The two metrics that were used for the periphyton assessment are the indicators of nutrient enrichment and trophic 

condition (Porter, 2008). The first metric, nutrient enrichment, 

is based on a weighted average (WA) of taxa that are indicative of either low or high nutrient conditions (Potapova and 

Charles, 2007). The WA metric was derived from the NAWQA 

database (http://infotrek.er.usgs.gov/nawqa_queries/biomaster/

index.jsp) by scientists from ANSP. The NAWQA data were 

divided into a national data set and five ecoregion data sets. 

Because there is evidence that diatom metrics or indices 

developed in one geographic area are less successful when 

applied in other areas (Potapova and Charles, 2007), the study 

Table 14. Fish Indexes of Biological Integrity (FIBI) for fish community data collected from the Meskwaki Settlement, central Iowa, 

2007.

[See table 1 for site descriptions: DNR, Department of Natural Resources; EPA, Environmental Protection Agency; FIBI, Fish Indexes of Biotic Integrity; 

WRP, Wetlands Reserve Property; --, not applicable]

Site number 

(fig. 1) Site name Iowa DNR FIBI1 Ohio EPA FIBI2 Classification

1 Iowa River near Montour, Iowa 42.1 28 Fair (Iowa FIBI)

Fair (Ohio EPA FIBI)

3 Onion Creek near Montour, Iowa 45.0 -- Fair (Iowa FIBI)

5 Iowa River at Highway 49 near Tama, Iowa 24.9 30 Poor (Iowa FIBI)

Fair (Ohio EPA FIBI)

7 Iowa River at WRP near Tama, Iowa 26.3 36 Fair (Iowa FIBI)

Fair (Ohio EPA FIBI)

1

 Iowa FIBI maximum score is 100. Scores are classified as 100–71 (excellent), 70–51 (good), 50–26 (fair), 25–0 (poor) (Wilton, 2004).

2

 Ohio EPA maximum score is 60. Scores are classified as 60–50 (excellent), 48–40 (good), 38–26 (fair), 24–16 (poor), less than 16 (very poor). (Ohio 

Environmental Protection Agency, 1987).

Table 15. Benthic Macroinvertebrate Index of Biological Integrity (BMIBI) for data collected from the Meskwaki Settlement, central 

Iowa, 2007.

[See table 1 for site descriptions: DNR Department of Natural Resources; BMIBI, Benthic Macroinvertebrate Index of Biological Integrity; WRP, Wetlands 

Reserve Property]

Site number (fig. 1) Site name Iowa DNR BMIBI1 Iowa BMIBI

classification

1 Iowa River near Montour, Iowa 53.8 Fair 

3 Onion Creek near Montour, Iowa 60.6 Good

5 Iowa River at Highway 49 near Tama, Iowa 67.2 Good 

7 Iowa River at WRP near Tama, Iowa 68.2 Good 

1

 Iowa BMIBI maximum score is 100. Scores are classified as 100–76 (excellent), 75–56 (good), 55–31 (fair), 30–0 (poor) (Wilton, 2004).
28 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

described in this report chose to use the diatom metrics for 

the Central and Western Plains level IV ecoregion delineated 

by Potapova and Charles (2007). The second metric, trophic 

condition of the water body (Van Dam and others, 1994), is 

described by a percentage of the total richness composed of 

taxa that are considered tolerant of eutrophic conditions. 

The WA metric results indicate that a large percentage of 

the diatom species that were collected from all of the ecological sampling sites within the Meskwaki Settlement indicate 

nutrient enriched conditions (table 16). On a scale from 0 to 

10, the lowest WA score was 8.78 and the highest was 10.0. 

As the WA metric results moved toward a WA score of 10 a 

greater expectation of nutrient enrichment occurs. The diatoms 

metric scores for low and high phosphorus as well as low and 

high nitrogen were assigned by Potapova and Charles (2007) 

on the basis of the following water-sample nutrient concentrations. Diatoms that were attributed to low WA scores corresponded to water samples with total phosphorus (TP) concentrations of less than or equal to 0.01 mg/L, whereas high WA 

scores corresponded to concentrations greater than or equal to 

0.1 mg/L. Diatoms that were attributed to a low WA score corresponded to water samples with total nitrogen (TN) concentrations less than or equal to 0.2 mg/L, and those diatoms that 

were attributed to a high WA score corresponded to concentrations greater than or equal to 3 mg/L. The implication of the 

WA metric results is that the species that were present at the 

Meskwaki Settlement sampling sites indicate nutrient enriched 

conditions. The nutrient data for the water samples that were 

collected during the same sampling period (table 16) also 

indicate nutrient enriched (eutrophic) conditions.

The trophic condition metric used in this periphyton 

assessment is from Van Dam and others (1994) and includes a 

new metric label that combines three of the trophic (TR) levels 

[mesotrophic-eutrophic (TR_ME), eutrophic (TR_ET), and 

polytrophic (TR_PT)] into one metric, eutrophic (TR_E). The 

percentage of taxa of species falling within metric codes 4, 5, 

and 6 (table 17) relative to the total taxa richness of all species 

samples was calculated and is shown in table 18. The range of 

trophic condition results for the four sites sampled for periphyton has TR_E values between 47.9 and 61.7 percent. These 

results show that at a minimum 47.9 percent of the species that 

are present show tolerance for or require large nutrient concentrations. The trophic conditions at the sampling sites show 

an imbalance in the trophic preferences by the species that 

are present. The results once again indicate that surface water 

within the Meskwaki Settlement could be considered nutrient 

enriched, which leads to greater potential for primary production and possibly eutrophic conditions.

Documentation has shown that intense row crop production and confined animal feeding operations in Iowa, Illinois, 

and southern Minnesota have resulted in accelerated nutrient 

and organic enrichment in tributary streams as well as in the 

Mississippi River (Goolsby and others, 1991; Coupe and others, 1995). This documented enrichment of the upper Midwest 

is consistent with the ecological results found during the 2007 

sampling cycle of the surface water within the Meskwaki 

Settlement. 

Fish Tissue 

During the summer of 2007, fish-tissue data were collected on the Meskwaki tribal lands for analysis of selected 

organochlorine, trace metals, and organic wastewater contaminants. Detection of organochlorine pesticides, and trace metals 

within fish tissue has led to the posting of fish-consumption 

advisories all across the United States. In 2005, 26 percent of 

the nation’s river miles were under fish-consumption advisories (U.S. Environmental Protection Agency, 2007a). 

Common carp were chosen for tissue analysis because 

of the relative availability of these fish in Iowa rivers and 

streams. Common carp feed on invertebrates and detritus near 

the stream bottom and, because organochlorines sorb to sediment that tends to settle on the stream bottom, common carp 

have a propensity for greater exposure to organochlorines. 

Table 16. Weighted average (WA) results for periphyton community data collected from the Meskwaki Settlement, central Iowa, 

2007.

[See table 1 for site descriptions: RNr ratio of high nitrogen and low nitrogen indicators, RPr ratio of high phosphorus and low phosphorus indicator species; 

WRP, Wetlands Reserve Property; mg/L, milligrams per liter]

Site number 

(fig. 1) Site name

Weighted averages1 Median total concentrations 

during sampling period 20072 Indication of 

weighted 

RNr RPr average Nitrogen 

(mg/L)

Phosphorus

(mg/L)

 1 Iowa River near Montour, Iowa 9.87 10 2.67 0.285 High nutrient

 3 Onion Creek near Montour, Iowa 10 9.96 1.30 .407 High nutrient

 5 Iowa River at Highway 49 near Tama, Iowa 9.25 9.94 13.6 .126 High nutrient

 7 Iowa River at WRP near Tama, Iowa 9.63 8.78 13.7 .125 High nutrient

1

 Weight average scale 0 to 10: 0 being low indicator of nutrient enrichment, 10 being high indicator of nutrient enrichment (Potapova, and Charles, 2007).

2

 High nitrogen greater than or equal 3 mg/L; Low nitrogen less than or equal to 0.2 mg/L: High phosphorous greater than or equal to 0.1 mg/L: Low 

phosphorous less than or equal to 0.01 mg/L.
Biological Assessment 29

Two separate tissues, fillets and liver, were dissected and 

removed from the sampled fish. The carp were filleted, and the 

fillets were sent to the NWQL for organochlorine and organic 

wastewater contaminant analysis. The livers were preserved 

and sent to the NWQL for organochlorine, trace metal, and 

organic wastewater contaminant analysis. 

Due to the size of Onion Creek, there were not any large 

bottom-dwelling fish species that could be dissected for analysis. To provide an assessment of organochlorine and organic 

wastewater contaminant concentrations in the fish tissue from 

Onion Creek, creek chubs (Semotilus atromaculatus) were 

collected and processed. Creek chubs were chosen at this site 

on the basis of availability. The creek chub fish-tissue analysis 

included eight composited whole fish, the livers of which were 

a composite of all eight fish livers for the analysis of organochlorine and organic wastewater contaminants. An assessment 

of the trace metal concentration in the fish tissue at the Onion 

Creek site was not done because the mass of tissue needed for 

processing could not be collected due to the small size of the 

fish that are present in the creek. The methods used for the dissection and processing of the fish are documented in Crawford 

and Luoma (1993). 

The purpose of the fish tissue assessment was to 

document the level of contamination within the fish-tissue 

samples and whether or not they were at a level that would 

affect human health. To objectively provide a risk to human 

health from the consumption of fish on the settlement, a few 

important concerns were addressed. First, fish-tissue contamination levels for human consumption are based on the 

fish fillet samples; livers typically are not used for humanhealth concerns because the general population commonly 

does not consume fish liver tissue. Liver tissue is used most 

widely for determining occurrence and distribution of contaminants in the fish population. Therefore, any contaminant 

detected in the fish liver tissue is discussed in the following 

paragraphs as occurring in the fish tissue and not in terms of 

human-health concerns.

For the State of Iowa, there are three different contamination levels that are provided by three separate government 

agencies. The first being the U.S. Food and Drug Administration (FDA) action levels (U.S. Food and Drug Administration, 2000), which are guidelines used for fish that are bought 

and sold in the marketplace. The FDA action levels represent 

a limit at or above which the FDA may take legal action to 

Table 17. Trophic conditions defined for periphyton community data collected from the Meskwaki Settlement, central Iowa, 2007.

Metric label1 Metric code Metric name Metric description

TR_OL 1 Oligotraphentic diatoms Oligotrophic

TR_OM 2 Oligotraphentic – mesotraphentic diatoms Oligotrophic-mesotrophic

TR_MT 3 Mesotraphentic diatoms Mesotrophic

TR_ME 4 Mesotrapentic – eutraphentic diatoms Mesotrophic-eutrophic

TR_ET 5 Eutrophentic Eutrophic

TR_PT 6 Hypereutraphentic Polytrophic

TR_EY 7 Eurytraphentic diatoms Indifferent—wide range of tolerance nutrients

TR_E 4+5+6 Eutrophic diatoms Tolerance or requirements of large nutrient concentrations

1

 See metric description from Van Dam and others (1994).

Table 18. Trophic condition results for periphyton community data collected from the Meskwaki Settlement, central Iowa, 

2007.

[See table 1 for site descriptions: TR_E, eutrophic diatom metric, indicates percentage of taxa in metric codes 4, 5, 6 (table 15); %, percent; WRP, 

Wetlands Reserve Property; mg/L, milligrams per liter]

Site number 

(fig. 1) Site name TR_E

Median total concentrations 

during sampling period 2007 Indication of trophic 

Nitrogen condition

(mg/L)

Phosphorus 

(mg/L)

1 Iowa River near Montour, Iowa 60.5 % 2.67 0.285 High nutrient

3 Onion Creek near Montour, Iowa 61.7% 1.30 .407 High nutrient

5 Iowa River at Highway 49 near Tama, Iowa 54.3 % 13.6 .126 High nutrient

7 Iowa River at WRP near Tama, Iowa 47.9 % 13.7 .125 High nutrient

1

 Large nitrogen concentration greater than or equal 3 mg/L; small nitrogen concentrations less than or equal to 0.2 mg/L Large phosphorus concentrations greater than or equal to 0.1 mg/L: small phosphorous concentrations less than or equal to .01 mg/L (from Van Dam and others, 1994).
30 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

remove products from the marketplace (U.S. Environmental 

Protection Agency, 2000). The FDA methodology to determine these action levels was never intended to be protective 

of recreational, tribal, ethnic, and sustenance fishers who 

typically consume larger quantities than the general population 

(U.S. Environmental Protection Agency, 2000). The USEPA 

uses a risk-based approach at setting levels called screening 

values (SVs). Both the USEPA and the FDA agree that the 

USEPA’s risk-based approach is favorable to determine local 

fish consumption advisories (U.S. Environmental Protection 

Agency, 2000). Exceedance of a USEPA SV should be taken 

as an indicator that more site-specific monitoring and/or evaluation of human risk is needed (U.S. Environmental Protection 

Agency, 2000). The Iowa Department of Public Health (IDPH) 

has used a combination of the FDA action levels and the 

USEPA’s risk-based levels to develop advisory levels for water 

within Iowa’s borders (Iowa Department of Natural Resources, 

2006). The SVs from the USEPA and the action levels from 

the FDA are only guidelines and not regulatory values. The 

three different advisory levels are described in table 19.

Of the selected organochorines analyzed in the fish fillet tissue, samples from three Iowa River sites exceeded the 

USEPA SV (table 20) for dieldrin of 0.0025 parts per million 

(ppm; U.S. Environmental Protection Agency, 2000). Dieldrin 

also was found in large concentrations in liver samples from 

all of the sites (table 21). Lipophilic contaminants, such as 

organochlorines, tend to accumulate in fatty tissues of fish, 

and the liver is a storage area for fats, which could explain the 

larger concentrations of dieldrin in this organ. Generally, the 

liver is not consumed, so the human health risk may be considered low. Dieldrin is an organochlorine insecticide that was 

banned completely from production in 1974 by the USEPA 

and for which all uses were voluntarily banned by industry 

in 1987 (U.S. Environmental Protection Agency, 2000). The 

USEPA SV is used as a management tool for this contaminant 

when detected in fillet tissue because the IDPH has not developed advisory levels for dieldrin. 

Trace metal concentrations in fish tissue were analyzed 

using dissected carp liver. Once again fish liver tissue is used 

most commonly as a tool to determine the occurrence of a 

contaminant in the environment and typically is not used to 

assess fish or human-health concerns. Both cadmium and 

mercury were found at concentrations that would warrant fishconsumption advisories if these levels were detected in the fish 

fillet tissue (table 22). 

The fish-tissue samples also were analyzed for organic 

wastewater contaminants. Current (2008) research is documenting that there are many chemical and microbial constituents in the environment that have not been considered 

previously as contaminants. A USGS study (Koplin and 

Table 19. Comparison of consumption advisory protocols for whole or fillet-fish tissue samples.

[FDA, U.S Food and Drug Administration; IDPH, Iowa Department of Public Health; USEPA, U.S.Environmental Protection Agency; ppm, parts per million; PCBs, polychlorinated biphenyls; DDT, dichloro-diphenyl-trichloroethane]

Contaminants FDA action 

level1 (ppm)

USEPA screening 

value2 (ppm)

IDPH advisory 

level3 (ppm) Consumption allowance for IDPH

Organochlorines

Chlordane (sum of all degradates) 0.3 0.114 0 to 0.6 

0.6 to 5.0

5.0 and over 

Unrestricted consumption

One meal per week

Do not eat

DDT (sum of all degradates) 5.0 .117 none Use USEPA value for recreation fishers

Dieldrin .3 .0025 none Use USEPA value for recreation fishers

PCBs (sum of all degradates) 2.0 .02 0 to 0.2 

0.2 to 1.0

1.0 and over

Unrestricted consumption

One meal per week

Do not eat

Trace metals

Arsenic none 1.2 none Use USEPA value for recreation fishers

Cadmium none 4.0 none Use USEPA value for recreation fishers

Mercury 1.0 .40 0 to 0.2

0.2 to 1.0

1.0 and over

Unrestricted consumption

One meal per week

Do not eat

Selenium none 20.0 none Use USEPA value for recreation fishers

1

 U.S. Food and Drug Administration (2000), Modified from Iowa Department of Natural Resources (2006).

2

 U.S. Environmental Protection Agency (2000).

3

 Iowa Department of Natural resources (2006).
Biological Assessment 31

others, 2002) documented that detectable quantities of organic 

wastewater contaminants occur in U.S. streams at a national 

scale. Little is understood about these contaminants, and ongoing research is developing analytical tools to better understand 

the transport and fate of the chemicals as well as the potential 

effect that these contaminants may have on organisms. The 

three most notable organic contaminants that were found in 

the fish tissue sampled in this study were a group of flameretardant chemicals known as polybrominated dephenyl ethers 

(PBDEs) as well as triclosan and its degradate methoxytriclosan (table 23). 

A class of flame retardants known as PBDEs is a group 

chemicals that are added to products to make them more difficult to burn. Some of the more common products are found 

in electronic enclosures (televisions), plastics used for business equipment, and foam in the cushioning of furniture. They 

are released into the environment during manufacture of the 

products and through consumer use of the products. PBDEs 

do not dissolve easily in water, and therefore, large concentrations of PBDEs are not found in water (Centers for Disease 

Control, Agency for Toxic Substances and Disease Registry, 

2004). The main source of human exposure to PBDEs may be 

through foods, particularly those with high fat content, such as 

fatty fish (Centers for Disease Control, Agency for Toxic Substances and Disease Registry, 2004). The fish-tissue samples 

collected on the Meskwaki Settlement had concentrations of 

PBDEs at all four of the sampling sites in both fillet and liver 

tissue. Although the flame retardant results in table 23 seem 

small, as of 2008 there are no regulations or advisory levels 

established for the consumption of fish with PBDEs present to make a determination if these values adversely affect 

human health.

Triclosan is a chemical found in many personal care 

products (antibacterial soaps, dish-washing detergents, 

toothpaste) and has been detected in water samples collected 

downstream from wastewater treatment facilities (Kolpin and 

others, 2002). Due to this relation to wastewater treatment 

facilities, it has been proposed that triclosan has the potential to be used as an indicator of human fecal contamination 

(Glassmeyer and others, 2005). Whole fish tissues sampled 

at Onion Creek site 3, which is downstream from the wastewater plant for the Meskwaki Settlement had concentrations 

Table 21. Results of analysis of selected organochlorine pesticides in fish liver or liver dilution samples collected from the 

Meskwaki Settlement, central Iowa, 2007.

[See table 1 for site descriptions; ppm, parts per million; WRP, wetlands reserve property; DDT, dichloro-diphenyl-trichloroethane; PCBs, polychlorinated 

biphenyls]

Site number (fig. 1) Site name Chlordane

(ppm)

DDT

(ppm)

Dieldrin

(ppm)

PCBs

(ppm)

1 Iowa River near Montour, IA1 0.0033 0.0875 0.0160 0.0053

3 Onion Creek near Montour, IA2 .0022 .0675 .0188 .0045

5 Iowa River at Highway 49 near Tama, IA1 .0003 0 .0184 .0018

7 Iowa River at WRP near Tama, IA1 .0002 .0552 .0113 .0059

1

 Whole liver

2

 Composite of fish liver

Table 20. Results of analysis of selected organochlorine pesticides in whole or fillet fish-tissue samples collected from the 

Meskwaki Settlement, central Iowa, 2007.

[See table 1 for site descriptions: ppm, parts per million is equal to milligrams per kilogram and micrograms per gram; USEPA, U.S. Environmental Protection Agency (2000); WRP, Wetlands Reserve Property; DDT, dichloro-diphenyl-trichloroethane; PCBs, polychlorinated biphenyls]

Site 

number 

(fig. 1)

 Site name

(whole fish or fillet samples)

Chlordane 

(ppm)

DDT

(ppm)

Dieldrin 

(ppm) 

PCBs

(ppm) Contamination level 

 1 Iowa River near Montour, IA2 0.0042 0.0332 0.0077 0.0063 Above USEPA Screening value for 

dieldrin

 3 Onion Creek near Montour, IA1 .0001 .0030 .0004 0 None

 5 Iowa River at Highway 49 near 

Tama, IA2

.0014 .0498 .0070 .0025 Above USEPA Screening value for 

dieldrin

 7 Iowa River at WRP near Tama, IA2 .0041 .0722 .0146 .0164 Above USEPA Screening value for 

dieldrin

1

 Composite of fish tissues

2

 Fillets only
32 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

of 0.0532 ppm of triclosan and 0.0285 ppm of the degradation product methoxytriclosan. Accumulation of triclosan in 

fish tissue has been linked to possible endocrine disruption 

resulting in sexual dimorphic traits within fish anatomy. Foran 

and others (2000) documented that changes in fin length and 

nonsignificant trends in sex ratio suggest triclosan is potentially weakly androgenic. The effects from consumption of 

fish with concentrations of triclosan on human health are not 

understood at this time although ongoing research is taking 

place to determine the effects of triclosan exposure on the 

human population. 

The fish-tissue sample results indicated the need for 

further study of contamination levels and potential health 

effects so that effective fish-consumption advisory levels can 

be developed for the Meskwaki Settlement.

Physical Habitat 

Physical habitat assessments are important to the analysis of the overall condition of a river or stream. Ecological 

studies have implicated or directly shown that habitat is an 

important determination of the distribution and abundance 

of fishes and aquatic invertebrates in streams (Stalnaker and 

others, 1995). There is a significant relation between in-stream 

physical habitat and the survival of aquatic communities. 

This relation is such that high-quality instream habitat tends 

to increase aquatic species diversity. An example of this in 

regards to fish is that young, juvenile, and adult fish have different habitat type preferences. It has been documented that 

shallow shoreline and backwater areas are important to the 

rearing and refuge of small fish species as well as juvenile 

large species of fish (Greenberg and others, 1996). To assess 

the quality of the in-stream physical habitat for this study, the 

Qualitative Habitat Evaluation Index (QHEI) was determined 

Table 22. Results of analysis of selected trace metals in fish-liver samples collected from the Meskwaki Settlement, central Iowa, 

2007.

 [See table 1 for site descriptions; ppm, parts per million; WRP, Wetlands Reserve Property]

Site number 

(fig. 1) Site name Arsenic(ppm)

Cadmium

(ppm)

Mercury 

(ppm)

Selenium 

(ppm)

1 Iowa River near Montour, IA 0.537 7.2 0.205 8.9

3 Iowa River at Highway 49 near Tama, IA .401 3.3 .061 3.6

5 Iowa River at WRP near Tama, IA .886 18.5 .285 12.2

Table 23. Results of analysis of selected organic wastewater contaminants in fish-tissue samples collected from the Meskwaki 

Settlement, central Iowa, 2007.

 [See table 1 for site descriptions; ND, not detected; ppm, parts per million; WRP, Wetlands Reserve Property]

Site number

(fig.1) Site name Flame retardants (ppm)

Methoxytriclosan 

(ppm) Triclosan 

(ppm)

 Whole fish or fillet samples

 1 Iowa River near Montour, IA2 0.0007 ND ND

 3 Onion Creek near Montour, IA1 .0352 0.0285 0.0532

 5 Iowa River at Highway 49 near Tama, IA2 .0051 ND ND

 7 Iowa River at WRP near Tama, IA2 .0139 ND ND

 Liver or liver dilutions

 1 Iowa River near Montour, IA4 .0088 ND ND

 3 Onion Creek near Montour, IA3 .0164 ND ND

 5 Iowa River at Highway 49 near Tama, IA4 .0112 ND ND

 7 Iowa River at WRP near Tama, IA4 .0126 ND ND

1

 Composite of fish tissues

2

 Fillets only

3

 Composite of fish livers

4

 Whole liver
Biological Assessment 33

to be most useful. The QHEI was first developed by the Ohio 

EPA in 1989 (Rankin, 2006). The QHEI index was selected 

for this study because it is used extensively in the Midwestern 

United States (Frimpong and others, 2005). The individual 

metrics used in the QHEI index are described in table 24. The 

values of the individual QHEI metrics are summed, and the 

results are assigned a narrative range or classification. Rankin 

(2006) cautions that habitat effects on aquatic life, however, 

occur at multiple spatial scales and that narrative ranges are 

general and not always predictable of aquatic assemblages at 

any given site. The results of the QHEI for the sampling sites 

on the Meskwaki Settlement are found in table 25.

The results of the QHEI for the Iowa River sites seem 

to be consistent with the results of the FIBI at the same 

Iowa River sites, which resulted in similar classifications of 

fair. One exception was the Iowa River at Highway 49 near 

Tama (site 5), which had an Iowa FIBI classification of poor 

(table 14); this again could be related to the difficult sampling 

conditions during the fish survey. However, the Ohio EPA 

FIBI indicated a fair classification for the same site. The Ohio 

FIBI is not as affected by the sample size as the Iowa FIBI. 

The Iowa River sites showed little sign of disturbance; the 

multiple series of meanders and bends along with the large 

riparian buffer zone are what increased the QHEI scores for 

the Iowa River sampling sites. 

Onion Creek near Montour (site 3) had a QHEI classification of poor (table 25). This is not consistent with the 

FIBI classification, which had a result of fair (table 14). The 

metrics that comprise the QHEI reflect poorly on the Onion 

Creek site. Onion Creek is a stream that has been straightened 

to meet anthropogenic needs, which has resulted in a stream 

with characteristics that lack sinuosity and a lack of available 

habitat. A high degree of sinuosity typically provides channel 

characteristics that allow increased diversity of habitat and 

fauna (Barbour and others, 1999). Sinuosity allows for the 

absorption of the energy during high flows, protects the stream 

from excessive erosion and flooding, and provides refuge for 

benthic invertebrates and fish during storms (Barbour and others, 1999). The straightening of the channel on Onion Creek 

has adversely affected the quality of the in-stream habitat. 

The FIBI for Onion Creek likely resulted in a classification of fair because recent rainfall resulted in a water-surface 

elevation above previously observed stages. The fish survey took place during a time when Onion Creek was able 

to provide stream margin habitat, which would lead to the 

potential for a more diverse fish community. Natural, variable 

Table 24. Individual metrics for the Ohio Environmental Protection Agency Qualitative Habitat Evaluation Index (QHEI) used in 

physical habitat assessment.

Metric 

number Metric name Metric definition1

1 Substrate Two parts—substrate type (does one type dominate?) and substrate quality (embeddedness). Maximum possible score is 20. 

2 In-stream cover Includes presence of in-stream cover type and amounts of cover. Maximum possible score 

is 20.

3 Channel morphology Include four parts—sinuosity, development, channelization, and stability. Maximum possible score is 20

4 Bank erosion and riparian zone Three parts—erosion, riparian width, flood-plain quality. Maximum possible score is 10.

5a Pool and current Includes maximum pool depth, channel width, and current velocity. Maximum possible 

score is 12.

5b Riffle and run Includes riffle depth, run depth, riffle/run substrate type, and embeddedness. Maximum 

possible score is 8.

6 Gradient Metric score based on severity of gradient. Maximum possible score is 8.

1

 Adapted from Rankin (2006).

Table 25. Results of Qualitative Habitat Evaluation Index (QHEI) assessment of physical habitat data collected from the Meskwaki 

Settlement, central Iowa, 2007.

[See table 1 for site descriptions: Ohio EPA, Ohio Environmental Protection Agency; WRP, wetlands reserve property]

Site number (fig. 1) Site number Ohio EPA QHEI1 Classification

 1 Iowa River near Montour, IA 54.5 Fair

 3 Onion Creek near Montour, IA 32.5 Poor

 5 Iowa River at Highway 49 near Tama, IA 54.5 Fair

 7 Iowa River at WRP near Tama, IA 54.5 Fair

1

 Ohio EPA QHEI narrative ranges: greater than 75 excellent, 60–74 good, 45–59 fair, 30–44 poor, less than 30 very poor (Rankin, 2006).
34 Water-Quality and Biological Assessment of the Iowa River and Tributaries, Meskwaki Settlement, 2006–07

flows create and maintain the dynamics of in-channel and 

flood-plain conditions and habitats that are essential to aquatic 

and riparian species (Poff and others, 1997). This increase in 

flow would have allowed fish species that had taken refuge 

in downstream habitats, such as the Iowa River, to travel 

upstream to utilize the new habitat that the rainfall had 

created. 

The data used to calculate the QHEI for Onion Creek 

were collected under conditions with less streamflow than the 

fish survey. The results of the QHEI were representative of the 

conditions at the time of measurement. 

Summary and Conclusions

In cooperation with the Sac and Fox Tribe of the Mississippi in Iowa (Meskwaki Nation), the U.S. Geological Survey 

conducted a 2-year baseline assessment of the chemical and 

biological quality of streams within the Meskwaki Settlement 

in central Iowa. The Meskwaki Nation is a federally recognized tribe that wishes to establish water-quality standards 

to safeguard the integrity of surface waters and aquatic biota 

within the settlement for the health and welfare of the tribal 

community. The settlement is drained by the Iowa River and 

four tributaries (Onion, Cattail, Raven, and Bennett Creeks). 

Water-quality samples were collected at three sites on the Iowa 

River, two sites on Onion Creek, and one site each on Cattail, Raven, and Bennett Creeks from April 2006 through July 

2007. Biological and habitat assessments were conducted at all 

three sites on the Iowa River and the downstream-most site on 

Onion Creek from June through August 2007.

The physical, chemical, and biological compositions 

of surface water in the Iowa River and its tributaries are in 

a constant flux, both spatially and temporally, owing to the 

dynamic relation between climate, streamflow, stream morphology, and land-use practices. Water quality, therefore, typically falls within a range of values for a specific body of water 

under a specific set of conditions. It is this range that defines 

the baseline conditions for streams throughout the Meskwaki 

Settlement.

Water temperature, specific conductance, pH, and 

dissolved-oxygen concentrations did not indicate any adverse 

water-quality conditions during this study. The majority of 

surface water sampled within the Settlement was predominately a calcium-bicarbonate type. Grouping of major ion 

data on a trilinear plot indicate that Sites 2 and 3 on Onion 

Creek and Site 8 on Cattail Creek represent more urban influences in contrast with the Iowa River and Raven and Bennett 

Creeks, which largely represent agricultural influences. None 

of the samples analyzed for trace metals had concentrations 

exceeding the respective MCLs or the State of Iowa criteria 

for chronic or acute toxicity. Of the five analytes for which 

secondary MCL’s exist, only manganese was found to exceed 

its respective SMCL of 50 micrograms per liter (mg/L).

High concentrations of soluble manganese may indicate 

anthropogenic input to the surface-water system, but it is 

unknown what the actual source(s) may be. About 62 percent 

of the nitrate samples collected from the Iowa River exceeded 

the USEPA MCL of 10 mg/L for drinking water as compared 

to 0 percent of the samples from Onion and Cattail Creeks and 

43 percent from Raven and Bennett Creeks. Atrazine, simazine, and alachlor are on the State and USEPA’s list of contaminants for primary drinking water but none were present in 

concentrations that exceeded their respective MCL. Chloripyrifos is regulated by the State and ranged in concentrations 

from 0.005 to 0.01 μg/L.

 Tests were conducted to determine the presence of 

wastewater contaminants in water samples collected from 

Onion Creek upstream and downstream from the Meskwaki 

sewage lagoons outflow; Cattail Creek downstream from the 

tribal headquarters and central housing complex; and the three 

sites along the Iowa River. Of the 67 compounds tested for, 

only nine quantifiable detections were recorded, in addition to 217 unquantifiable (estimated) detections. Six of the 

nine compounds detected were from the Onion Creek Site 3 

and included four perfume derivatives and an insect repellant. Phenol, of which there were three unquantifiable detections, is regulated by the State and ranged from estimates of 

0.008 to 0.172 μg/L. Tests also were conducted to determine 

the presence of fuel compounds in water samples collected 

from the same sites as the wastewater samples and included 

toluene, benzene, ethylbenzene, xylene, and tert-butyl methyl 

ether (MTBE). Of the 34 samples collected, only toluene was 

detected at a reporting limit of 0.1 mg/L. 

Bacteria samples were collected at all sites during this 

study and included Escherichia coli (E. coli) and fecal coliform. For waters designated as Class “A”, primary contact recreation, the State of Iowa’s maximum allowable E. coli content 

has been set at 235 colony forming units per 100 milliliters 

(cfu/100 mL) from March 15 through November 15, except 

when affected by surface runoff. Between April and October 

2006 and 2007, E. coli densities in samples from the Iowa 

River within and contiguous to the settlement ranged from 

less than 10 to 1,600 cfu/100 mL with a median value of about 

160 cfu/100 mL. E. coli densities in tributaries north of the 

Iowa River ranged from 73 to 880 cfu/100 mL in Onion Creek 

at the upstream site 2, and from 130 to 440,000 cfu/100 mL 

downstream from the sewage lagoons (site 3). E. coli densities 

measured south of the Iowa River in samples from Raven and 

Bennett Creeks ranged from 1,100 to 23,000 cfu/100 mL and 

270 to 33,000 cfu/100 mL, respectively.

Streambed sediment samples were collected in conjunction with the biological assessment from the three sampling 

sites along the Iowa River (Sites 1, 5, and 7) and from Onion 

Creek downstream from the sewage lagoons. 

The USGS and the Meskwaki Nation, with assistance 

from the USFWS, collected and identified fish, benthicmacroinvertebrate, periphyton, and physical habitat data at four sites 

within the Meskwaki Settlement to provide baseline information. Selected Indexes of Biologic Integrity (IBI) were used 
References Cited 35

that provide quantifiable values to assess the current condition 

of the fish and macroinvertebrate communities. The index 

scores were classified on the basis of a tiered system that 

places the scores into a classification of excellent, good, fair, 

or poor. The classifications then were compared to Iowa DNR 

reference sites to evaluate how the Meskwaki sites compare 

in the State of Iowa. The algae community was assessed 

using two separate metrics—one based on a weighted average of taxa by using a ratio of high to low nutrient enrichment 

indicator species and the other based on the percentage of total 

taxa richness composed of eutrophic indicator species present. These metric scores provide a quantifiable value to assess 

the level of nutrient enrichment and trophic condition that 

exists. An assessment of the physical habitat was determined 

using a qualitative technique. Additionally, fish-tissue samples 

were collected and analyzed for selected organochlorine, trace 

metal, and organic wastewater contaminant bioaccumulation.

The fish IBI indicated that the health of the fish population was similar to what was expected within the level 

IV ecoregion (47f) in Iowa. On the basis of index scores, 

the Iowa River sites and the Onion Creek site all indicated 

a fair classification with one exception, the Iowa River at 

Highway 49 near Tama (site 5), which had a poor classification. This poor classification could be related to the difficult 

sampling conditions. 

The benthic macroinvertebrate IBI indicated that the 

health of the macroinvertebrate population was good at all 

of the sites other than the Iowa River near Montour (site 1), 

which was rated fair. A classification of good could be considered better than what would be expected at comparable 

streams within ecoregion 47f. 

The periphyton metrics for the species that were present 

indicated that the potential for eutrophic conditions existed. 

The water within the Meskwaki Settlement was considered 

nutrient enriched, leading to greater potential for primary 

production and possibly a eutrophic condition. 

The insecticide dieldrin was detected in the fish liver 

tissue at all four of the sites sampled. Dieldrin also was found 

in fillet tissue samples at the three Iowa River sites at concentrations above the USEPA screening value. Detections at 

the Onion Creek near Montour (site 3) were confined to the 

liver tissue. The USEPA screening values are guidelines and 

not regulatory; they are provided as a management tool for 

natural-resource managers. Both cadmium and mercury were 

found in liver tissue samples at concentrations that would warrant fish consumption advisories if these levels were detected 

in the fillet fish tissue. Of the organic wastewater contaminants 

that were found in the fish tissue sampled in this study, there 

were three that were most notable—a group of flame-retardant 

chemicals known as polybrominated dephenyl ethers (PBDEs) 

as well as the antibacterial agent triclosan and its degradate 

methoxytriclosan. These contaminants currently (2008) do not 

have any fish consumption advisory recommendations by any 

of the regulatory agencies in Iowa. 

The qualitative habitat evaluation index (QHEI) was used 

to assess the condition of the physical habitat. The Iowa River 

sites resulted in a QHEI score and a classification of fair. In 

contrast, the Onion Creek site located downstream from settlement sewage lagoons resulted in an evaluation of poor. These 

results were indicative of the conditions observed during data 

collection. Onion Creek has been straightened throughout the 

majority of its drainage. This has lead to a loss of sinuosity, 

which can lead to the inability of the stream to develop and 

provide in-stream habitat for fish and invertebrates during all 

flow conditions. Sinuosity and in-stream habitat are important 

factors in the QHEI used to provide this analysis. In contrast, 

the Iowa River sites scored well in the habitat assessment due 

to several factors including the greater number of meanders 

and bends that are indicative of a sinuous stream. The Iowa 

River sites also had large riparian zones. 

Acknowledgments

The authors thank the Meskwaki Natural Resources 

Department personnel for their assistance in project planning 

and coordinating access to sampling sites. Special recognition 

goes to Kelly Schott and Kathy Noe of the Meskwaki Natural 

Resources Department and Doug Goodrich, Jon Nania, Scott 

Strader, Jim Cerveny, Clint Van Schepen, Aimee Donnelly, 

and David Smith of the U.S. Geological Survey for their 

assistance with the collection and processing of water-quality 

samples, the measurement of streamflow, and the biological assessment. Additional thanks go to Nick Paretti, Kymm 

Barnes, Mark Munn, and Lanna Combs for their much appreciated technical and editorial reviews of this report.

References Cited

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Averett, R.C., and Schroder, L.J., 1994, A guide to the design 

of surface-water-quality studies: U.S. Geological Survey 

Open-File Report 93–105, 39 p.

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Glossary 41

Glossary

Analyte A substance or chemical constituent that is undergoing analysis.

Androgenic Pertaining to the stimulation or control of the 

development and maintenance of masculine characteristics.

Anthropogenic Caused or produced by humans, commonly 

used in reference to environmental effects. 

Backwater Water backed up or retarded in its course as 

compared with its normal or natural condition of flow.

Base flow Sustained or fair-weather runoff composed largely 

of groundwater discharge, in most streams. 

Baseline data A reference set of initial conditions used for 

comparison with data collected at a later time for the purpose 

of interpreting changes over time. 

Benthic Pertaining to the biogeographic region that includes 

the bottom of a lake, river, sea, or ocean. 

Ephemeral A stream or portion of a stream which flows only 

in direct response to precipitation, and whose channel is at all 

times above the water table. 

Eutrophic Characterized by an abundant accumulation of 

nutrients that support a dense growth of algae and other organisms, the decay of which depletes shallow water of oxygen in 

summer.

Health Advisory Level (HAL) Also known as the Maximum 

Contaminant Level Goal (MCLG), the level below which no 

adverse noncarcinogenic health effects should result from a 

lifetime of exposure, assuming a consumption of 2 liters per 

day of drinking water. Exceeding this value does not mean that 

a specific set of adverse health effects will occur in humans 

ingesting the water. The risk of adverse health effects, however, increases.

Lipophilic Having an affinity for, tending to combine with, 

or capable of dissolving in lipids or fatty tissue.

Macroinvertebrate Traditionally used to refer to aquatic 

invertebrates including insects, crustaceans, molluscs and 

worms, which inhabit a river channel, pond, lake, wetland, or 

ocean and that are visible to the naked eye.

Maximum Contaminant Level (MCL) Maximum permissible 

level of a contaminant in water that is delivered to any user 

of a public water system. MCLs are enforceable regulations 

established by the U.S. Environmental Protection Agency. 

Microsiemens Metric unit of the measure of electric conductance.

Organochlorine An organic compound containing at least 

one covalently bonded chlorine atom. Organochlorines are 

persistent in the environment because they are resistant to 

rapid decomposition; they are, however, readily sorbed to sediment. Many pesticides used in society today are classified as 

organochlorines. 

PAHs Polycyclic aromatic hydrocarbons are produced as 

byproducts of fuel burning or incomplete combustion of 

organic materials. 

Periphyton A complex matrix of algae attached to submerged substrata in almost all aquatic ecosystems.

Riparian Pertaining to the banks of a river or stream.

Secondary Maximum Contaminant Level (SMCL) Nonenforceable guidelines regulating contaminants that may cause 

cosmetic or aesthetic effects in drinking water. 

Sinuosity The ratio of channel length between two points 

on a channel to straight line distance between the same two 

points; a method of measuring the meandering of a river.

Storm flow Increase in stream discharge resulting from direct 

precipitation and surface runoff entering stream channels 

promptly after rainfall. 

Synoptic measurements Measurements taken concurrently 

at multiple locations for the purpose of documenting conditions at a given time. 

Water year In U.S. Geological Survey reports dealing with 

surface-water supply, the 12-month period, October 1 through 

September 30. The water year is designated by the calendar 

year in which it ends. Thus, the year ending September 30, 

2007, is called the “2007 water year.”

Wetlands Reserve Property Property voluntarily set aside 

by the tribe to protect, restore, and enhance wetlands on the 

settlement through technical and financial support by the U.S. 

Department of Agriculture’s Natural Resource Conservation 

Service. 
Publishing support provided by:

Rolla Publishing Service Center

For more information concerning this publication, contact:

Director, USGS Iowa Water Science Center

400 South Clinton Street, Room #269

Iowa City, IA 52244–1230

(319) 337–4191

Or visit the Iowa Water Science Center Web site at:

http://ia.water.usgs.gov

Littin and Mc Vay—Water-Quality and Biological Assessment of the Iowa River, Meskwaki Settlement in Iowa—Scientific Investigations Report 2009–5105