U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1722

In cooperation with the Wisconsin Department of Natural Resources

Nutrient Concentrations and Their Relations to the 

Biotic Integrity of Wadeable Streams in Wisconsin

Nutrient Concentrations and Their 

Relations to the Biotic Integrity of 

Wadeable Streams in Wisconsin

By Dale M. Robertson, David J. Graczyk, Paul J. Garrison, Lizhu Wang, 

Gina LaLiberte, and Roger Bannerman

In cooperation with the Wisconsin Department of Natural Resources

Professional Paper 1722

U.S. Department of the Interior

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

P. Lynn Scarlett, Acting Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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Library of Congress Cataloging-in-Publication Data

Nutrient concentrations and their relations to the biotic integrity of wadeable streams 

in Wisconsin / by Dale M. Robertson ... [et al.] ; in cooperation with the Wisconsin 

Department of Natural Resources.

p. cm. -- (Professional paper ; 1722)

Includes bibliographical references and index.

ISBN 1-4113-0975-8 (alk. paper)

1. Water quality biological assessment--Wisconsin. 2. Nutrient pollution of water--Wisconsin. 

I. Robertson, Dale M. II. Series: Professional paper (Geological Survey (U.S.)) ; no. 1722.

QH96.8.B5N88 2006

577.6’42709775--dc22

2006006900

ISBN 1-4113-0975-8
iii

Contents

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

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

Purpose and Scope ..................................................................................................................... 8

Approach ..................................................................................................................................... 10

Methods of Data Collection and Analysis ...................................................................................... 10

Field Methods ............................................................................................................................. 10

Discharge, Water Chemistry, and Suspended Chlorophyll a Concentrations ........ 10

Benthic Chlorophyll a and Diatoms ............................................................................... 12

Physical Habitat and Fish ............................................................................................... 12

Macroinvertebrates ........................................................................................................ 13

Watershed Boundaries and Environmental Characteristics .............................................. 13

Data Summaries ......................................................................................................................... 14

Statistical Methods.................................................................................................................... 16

Normalization..................................................................................................................... 16

Correlations and Regressions ....................................................................................... 16

Simultaneous Partial Residualization ............................................................................ 16

Regression-Tree Analysis ................................................................................................ 17

Redundancy Analysis ....................................................................................................... 17

Statistical Differences among Groups .......................................................................... 18

Water Quality and Its Relations with Environmental Characteristics in the Watershed ........ 19

Relations between Water Quality and Environmental Characteristics in the 

Watershed .................................................................................................................... 21

Correlations between Individual Characteristics ........................................................ 21

Correlations with Individual Characteristics after Removing Relations 

with Anthropogenic Characteristics ....................................................... 24

Thresholds in Water-Quality Responses....................................................................... 25

Effects of Multiple Environmental Characteristics on Water Quality ...................... 29

Stepwise Regression ............................................................................................. 29

Redundancy Analysis .............................................................................................. 31

Environmental Characteristics Most Strongly Related to Water Quality ............... 32

Regionalization Schemes for Reference Water Quality and the Response in 

Water Quality to Changes in Land Use ..................................................................... 34

Reference Water-Quality Conditions ............................................................................. 34

Total Phosphorus .................................................................................................... 38

Total Nitrogen .......................................................................................................... 38

Suspended Chlorophyll a ....................................................................................... 39

Secchi Tube Depth .................................................................................................. 40

Responses of Nutrient Concentrations to Changes in Land Use .............................. 40

Responses of Chlorophyll a Concentrations and Secchi Tube Depth to 

Changes in Nutrient Concentrations and Land Use ...................................... 45

Physical Habitat .................................................................................................................................. 48
iv

Benthic Chlorophyll a and Periphytic-Diatom Communities and Their Relations 

with Water-Quality, Environmental, and Physical-Habitat Characteristics ................. 51

Relations with Individual Characteristics ............................................................................. 51

Correlations ....................................................................................................................... 51

Responses to Changes in Nutrient Concentrations ................................................... 55

Effects of Multiple Characteristics on Benthic Chlorophyll a Concentrations and 

Diatom Indices .............................................................................................................. 59

Stepwise Regressions ..................................................................................................... 59

Redundancy Analysis ....................................................................................................... 59

Reference Values for Benthic Chlorophyll a Concentrations and Diatom Indices ......... 60

Macroinvertebrate Communities and Their Relations with Water-Quality, 

Environmental, and Physical-Habitat Characteristics .................................................... 62

Relations with Individual Characteristics ............................................................................. 62

Correlations ....................................................................................................................... 62

Response to Changes in Nutrient Concentrations ..................................................... 66

Effects of Multiple Characteristics on Macroinvertebrate Indices .................................. 69

Stepwise Regressions ..................................................................................................... 69

Redundancy Analysis ....................................................................................................... 70

Reference Values for the Macroinvertebrate Indices ......................................................... 70

Fish Communities and Their Relations with Water-Quality, Environmental, and 

Physical-Habitat Characteristics ........................................................................................ 72

Relations with Individual Characteristics ............................................................................. 72

Correlations ....................................................................................................................... 72

Responses to Changes in Nutrient Concentrations ................................................... 76

Effects of Multiple Characteristics on Fish Indices ............................................................. 76

Stepwise Regressions ..................................................................................................... 76

Redundancy Analysis ....................................................................................................... 80

Reference Values for the Fish Indices ................................................................................... 80

Multiparameter Biotic Indices to Estimate Nutrient Concentrations in Wadeable 

Streams ................................................................................................................................... 82

Summary and Conclusions ................................................................................................................ 84

Final Regionalization Scheme for Wisconsin Streams ........................................................ 84

Reference Conditions ................................................................................................................ 86

Responses of Water Quality to Changes in Land Use ........................................................ 88

Responses of Biotic Indices to Changes in Nutrient Concentrations ............................... 88

Multiparameter Biotic Indices to Estimate Nutrient Concentrations in 

Wadeable Streams ....................................................................................................... 89

Nutrient Concentrations Controlling the Biotic Integrity of Streams ................................ 90

Literature Cited .................................................................................................................................... 91

Appendixes .......................................................................................................................................... 95
v

Figures

 1. National nutrient ecoregions and major land uses in the upper Midwest ................ 4

 2. Two regionalization schemes considered for wadeable streams in 

Wisconsin: A, level III ecoregions with major land-use/land-cover categories 

and B, environmental phosphorus zones ........................................................................ 5

 3. Environmental phosphorus zones in the upper Midwest ............................................. 7

 4. Sites on wadeable streams in Wisconsin included in this study .............................. 11

 5. Distributions of median monthly total phosphorus, total nitrogen, and 

suspended chlorophyll a concentrations, and Secchi tube depth ............................ 20

 6. Total phosphorus and total nitrogen concentrations as a function of the 

percentage of total agriculture in the watersheds of the studied wadeable 

streams in Wisconsin ........................................................................................................ 27

 7. Suspended chlorophyll a concentrations and Secchi tube depths as a 

function of median total phosphorus and total nitrogen concentrations ................. 28

 8. Percentages of explained variance in water quality described by 

anthropogenic/land-use, basin, soil and surficial-deposit characteristics, 

and interactions among categories ................................................................................ 33

 9. Percentages of explained variance in A, Secchi tube depths and B, 

suspended chlorophyll a concentrations described by nutrients, 

environmental characteristics, and interactions among categories ........................ 33

 10. Percentiles of A, total agriculture in the watersheds, B, total phosphorus, 

and C, total nitrogen in streams in the level III ecoregions and environmental 

phosphorus zones .............................................................................................................. 35

 11. A, suspended chlorophyll a concentrations and B, Secchi tube depths in 

Reference sites, High sites, and sites with only reference total nitrogen 

or reference total phosphorus concentrations ............................................................ 39

 12. Total phosphorus concentrations as a function of the percentage of 

agricultural land use in A, environmental phosphorus zones and B,

level III ecoregions, and response curves for phosphorus concentrations 

as a function of the percentage of agriculture in the watershed, in C, EPZs, 

and D, level III ecoregions ............................................................................................... 41

 13. Total nitrogen concentrations as a function of the percentage of 

agricultural land use in A, environmental phosphorus zones and B,

level III ecoregions, and response curves for nitrogen concentrations 

as a function of the percentage of agriculture in the watershed, in C, EPZs, 

and D, level III ecoregions ............................................................................................... 42

 14. Suspended chlorophyll a concentrations as a function of total phosphorus 

and total nitrogen concentration, by environmental phosphorus zones 

and by level III ecoregions ............................................................................................... 46

 15. Secchi tube depth as a function of total phosphorus and total nitrogen 

concentration, by environmental phosphorus zones and by level III 

ecoregions .......................................................................................................................... 47
vi

Figures—Continued

 16. Response curves for A, suspended chlorophyll a concentrations and 

B, Secchi tube depths in the environmental phosphorus zones as a 

function of the percentage of agriculture in the watershed ...................................... 48

 17. Distributions of benthic chlorophyll a concentrations, Diatom Nutrient 

Index values, Diatom Siltation Index values, and Diatom Biotic Index values ........ 52

 18. Benthic chlorophyll a concentrations, Diatom Nutrient Index values, and 

Diatom Siltation Index values as a function of total phosphorus and total 

nitrogen concentration in the environmental phosphorus zones and 

level III ecoregions ............................................................................................................ 56

 19. Benthic chlorophyll a concentrations, Diatom Nutrient Index values, 

and Diatom Siltation Index values as a function of dissolved phosphorus, 

dissolved nitrite plus nitrate, dissolved ammonia, and total Kjeldahl 

nitrogen concentrations in the environmental phosphorus zones ............................ 57

 20. Benthic chlorophyll a concentrations and Diatom Nutrient Index values 

for five nutrient categories ............................................................................................... 58

 21. Percentage of explained variance in benthic chlorophyll a concentrations 

and diatom index values described by nutrients, other water-quality 

characteristics, environmental and physical-habitat characteristics, 

and interactions among categories ................................................................................ 60

 22. Benthic chlorophyll a concentrations, Diatom Nutrient Index, Diatom 

Siltation Index, and Diatom Biotic Index values in Reference sites, High 

sites, and sites with only reference total nitrogen or reference total 

phosphorus concentrations ............................................................................................. 61

 23. Distributions of macroinvertebrate Hilsenhoff Biotic Index values, the 

percentages of individuals that were Ephemeroptera, Plecoptera, or 

Trichoptera, and the percentages of taxa that were Ephemeroptera, 

Plecoptera, or Trichoptera ............................................................................................... 63

 24. Hilsenhoff Biotic Index values, the percentages of individuals that 

were Ephemeroptera, Plecoptera, or Trichoptera, and the percentages 

of taxa that were Ephemeroptera, Plecoptera, or Trichoptera as a 

function of total phosphorus and total nitrogen concentration in the 

environmental phosphorus zones and level III ecoregions ........................................ 67

 25. Hilsenhoff Biotic Index values, the percentages of individuals that 

were Ephemeroptera, Plecoptera, or Trichoptera, and the percentages 

of taxa that were Ephemeroptera, Plecoptera, or Trichoptera as a 

function of dissolved phosphorus, dissolved nitrite plus nitrate, 

dissolved ammonia, and total Kjeldahl nitrogen concentrations in the 

environmental phosphorus zones ................................................................................... 68

 26. Percentages of explained variance in six macroinvertebrate index 

values described by nutrients, other water-quality characteristics, 

environmental and physical-habitat characteristics, and interactions 

among categories .............................................................................................................. 70

 27. Hilsenhoff Biotic Index values, the percentages of individuals that 

were Ephemeroptera, Plecoptera, or Trichoptera, and the percentages 

of taxa that were Ephemeroptera, Plecoptera, or Trichoptera in 

Reference sites, High sites, and sites with only reference total nitrogen 

or reference total phosphorus concentrations ............................................................ 71
vii

 28. Distributions of fish Index of Biotic Integrity values, the percentages of 

the fish that are carnivorous, the percentages of fish considered pollution 

intolerant, and the number of fish caught ..................................................................... 73

 29. Fish Index of Biotic Integrity values, the percentages of fish considered 

pollution intolerant, and the percentages of the fish that are carnivorous 

as a function of total phosphorus and total nitrogen concentration in the 

environmental phosphorus zones and level III ecoregions ........................................ 77

 30. Fish Index of Biotic Integrity values, the percentages of fish considered 

pollution intolerant, and the percentages of the fish that are carnivorous 

as a function of dissolved phosphorus, dissolved nitrite plus nitrate, 

dissolved ammonia, and total Kjeldahl nitrogen concentrations in the 

environmental phosphorus zones ................................................................................... 78

 31. Percentages of explained variance in eight fish index values described 

by nutrients, other water-quality characteristics, environmental and 

physical-habitat characteristics, and interactions among categories .................... 80

 32. Fish Index of Biotic Integrity values, the percentages of the fish that 

are carnivorous, and the percentages of fish that are considered pollution 

intolerant in Reference sites, High sites, and sites with only reference 

total nitrogen or reference total phosphorus concentrations ................................... 81

 33. Measured and estimated A, total phosphorus and B, total nitrogen 

concentrations for the four-parameter regression models, C, measured 

phosphorus concentrations as a function of Biotic Index of total 

Phosphorus values, and D, measured nitrogen concentrations as a 

function of Biotic Index of total Nitrogen values .......................................................... 83

 34. Proposed regionalization scheme for defining nutrient criteria for 

wadeable streams in Wisconsin. .................................................................................... 85
viii

Tables

 1. Reference concentrations for total phosphorus, total nitrogen, and 

suspended chlorophyll a, and turbidity in selected national 

nutrient and level III ecoregions and environmental phosphorus zones ................... 9

 2. Summary statistics for median monthly water-quality and environmental 

characteristics of the watersheds of the sites in the studied wadeable 

streams in Wisconsin ........................................................................................................ 15

 3. Median and average monthly concentrations for total and dissolved 

phosphorus, suspended chlorophyll a, total nitrogen, nitrite plus nitrate, 

ammonia, and Kjeldahl nitrogen, and Secchi tube depths ......................................... 21

 4. Spearman correlation coefficients between median concentrations of 

total phosphorus, dissolved phosphorus, total nitrogen, nitrite plus nitrate, 

ammonia, total Kjeldahl nitrogen, median Secchi tube depths, suspended 

chlorophyll a concentrations, percentages of urban and agricultural areas, 

point-source loadings of phosphorus, and specific environmental 

characteristics ................................................................................................................... 22

 5. Spearman correlation coefficients between residualized logarithmically 

transformed median concentrations of total phosphorus, dissolved 

phosphorus, nitrogen, nitrite plus nitrate, total Kjeldahl nitrogen, ammonia 

and suspended chlorophyll a, median Secchi tube depths, and specific 

residualized environmental characteristics .................................................................. 26

 6. Results of forward stepwise-regression analyses used to explain the 

variance in raw and residualized water-quality concentrations ............................... 30

 7. Results from redundancy analysis between water-quality and environmental 

characteristics ................................................................................................................... 32

 8. Reference conditions for total phosphorus, total nitrogen, and suspended 

chlorophyll a concentrations, and Secchi tube depths in the environmental 

phosphorus zones and level III ecoregions .................................................................. 36

 9. Responses in total phosphorus total nitrogen, suspended chlorophyll a, 

and Secchi tube depth to changes in the percentage of agricultural land 

use in the watershed ......................................................................................................... 44

 10. Summary statistics for the physical-habitat characteristics and biotic 

indices ................................................................................................................................. 49

 11. Spearman rank correlation coefficients between benthic chlorophyll a

concentrations and diatom community indices, and median water-quality, 

environmental, and physical-habitat characteristics .................................................. 53 

 12. Thresholds or breakpoints in the responses of benthic chlorophyll a

concentrations and diatom indices to changes in nutrient concentrations ............ 55

 13. Percentiles of total phosphorus and total nitrogen concentrations for the 

studied streams having both benthic chlorophyll a and diatom index data ............ 55

 14. Results of forward stepwise-regression analysis to explain the variance 

in benthic chlorophyll a concentrations and the three diatom indices .................... 59

 15. Spearman rank correlation coefficients between macroinvertebratecommunity indices and median water-quality, environmental, and 

physical-habitat characteristics ..................................................................................... 64
ix

 16. Thresholds or breakpoints in the responses in macroinvertebrate 

indices to changes in nutrient concentrations ............................................................. 69

 17. Results of forward stepwise-regression analyses to explain variance 

in macroinvertebrate indices ........................................................................................... 69

 18. Spearman rank correlation coefficients (rs

) between fish-community 

indices and median water-quality, environmental, and physical-habitat 

characteristics ................................................................................................................... 74

 19. Thresholds or breakpoints in the responses in fish indices to changes 

in nutrient concentrations ................................................................................................ 79

 20. Results of forward stepwise-regression analyses to explain variance 

in fish indices ...................................................................................................................... 79

 21. Results of forward stepwise-regression analyses to explain variance 

in total phosphorus and total nitrogen concentrations with biotic 

indices ................................................................................................................................. 82

 22. Reference conditions for water quality, chlorophyll a, diatoms, 

macroinvertebrates, and fish indices for wadeable streams in Wisconsin ............ 87

 23. Summary of thresholds or breakpoints in the responses of suspended 

chlorophyll a concentrations, Secchi tube depth, and various biotic 

indices to changes in nutrient concentrations for the studied wadeable 

streams in Wisconsin ........................................................................................................ 89

Appendixes

1. Stream identification information, location information, and summary 

statistics for flow and water-quality data collected for each of the 240 

studied wadeable streams in Wisconsin. ...................................................................... 96

 2. Physical-habitat characteristics of each of the 240 studied wadeable 

streams in Wisconsin ...................................................................................................... 110

 3. Diatom nutrient-tolerance ranking for individual diatom taxa ................................. 124

 4. Biological data for each of the 240 studied wadeable streams in Wisconsin ...... 126


Conversion Factors

Multiply By To obtain

Length

micrometer (μm) 0.00003927 inch (in.)

millimeter (mm) 0.03937 inch (in.)

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 0.0002471 acre 

square centimeter (cm2) 0.001076 square foot (ft2)

square meter (m2) 10.76 square foot (ft2) 

square centimeter (cm2) 0.1550 square inch (in2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 0.2642 gallon (gal)

cubic centimeter (cm3) 0.06102 cubic inch (in3) 

cubic meter (m3) 35.31 cubic foot (ft3)

Flow rate

cubic meter per second (m3/s) 70.07 acre-foot per day (acre-ft/d) 

cubic meter per second per 

square kilometer [(m3/s)/km2]

91.49 cubic foot per second per square

 mile [(ft3/s)/mi2]

meter per second (m/s) 3.281 feet per second (ft/s)

millimeter per hour (mm/hr) 0.03937 inch per hour (in/hr)

millimeter per year (mm/yr) 0.03937 inch per year (in/yr) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound, avoirdupois (lb)

kilogram per square kilometer 

(kg/km2)

5.70992 pound per square mile (lb/mi2)

milligram (mg) 0.00003527 ounce, avoirdupois (oz)

milligram per square meter 

(mg/m2)

0.000003277 ounce, avoirdupois, per square foot 

(oz/ft2)

Hydraulic gradient

meter per kilometer (m/km) 5.27983 foot per mile (ft/mi) 

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

follows:

°F=(1.8×°C)+32

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).
xi

Abbreviations 

Ag Agricultural land

BCHL Benthic chlorophyll a

BIN Biotic Index of total Nitrogen

BIP Biotic Index of total Phosphorus

CARN% Percentage of fish that are top carnivores

DBI Diatom Biotic Index

DEM Digital Elevation Model

DFA Driftless Area level III ecoregion

DNI Diatom Nutrient Index

DP Dissolved phosphorus

DSI Diatom Siltation Index

EPT Ephemeroptera, Plecoptera, or Trichoptera 

EPTN% Percentage of macroinvertebrate individuals that were EPT

EPTTX% Percentage of macroinvertebrate taxa that were EPT

EPZ Environmental phosphorus zone

EV Explained Variance

FISHN Number of fish caught

FISHSPEC Number of fish species caught

GIS Geographic Information System

HBI Hilsenhoff Biotic Index

High Sites Sites with nutrient concentration above the upper 95-percent confidence 

limits for reference nutrient concentrations

IBI Fish Index of Biotic Integrity

INSECT% Percentage of fish that are insectivores

INTOL% Percentage of fish that are pollution intolerant

Log Logarithmic transformation to base 10

n number

N Nitrogen

NCHF North Central Hardwood Forest level III ecoregion

NLF Northern Lakes and Forests level III ecoregion

NH4

-N Dissolved ammonia

NO3-N Dissolved nitrite plus nitrate

NWIS National Water Information System

OEPA Ohio Environmental Protection Agency

OMNI% Percentage of fish that are omnivorous

p Probability

P Phosphorus

PtS Point-source loadings of phosphorus

r Pearson correlation coefficient

rs

 Spearman correlation coefficient

R2 Coefficient of determination

Ref Sites Sites with nutrient concentration below median reference concentrations 

Res Residualized

RDA Redundancy analysis

SCHL Suspended chlorophyll a
xii

SCRAP% Percentage of macroinvertebrates that are scrapers

SD Secchi tube depth

SHRED% Percentage of macroinvertebrates that are shredders

SPARTA Spatial regression-tree analysis

SWTP Southeastern Wisconsin Till Plains level III ecoregion

t tolerance-index value

TAXAN Number of macoinvertebrate taxa

TKN Total Kjeldahl nitrogen

TOL% Percentage of fish that are pollution tolerant

Urb Urban land

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

WDNR Wisconsin Department of Natural Resources

< Less than

% Percentage of

# Number
xiii

Acknowledgments

Technical Reviewers

Michael A. Miller, Water Resources Management Specialist, Wisconsin Department 

of Natural Resources, Madison, Wis.

Mark D. Munn, Stream Ecologist, U.S. Geological Survey, Tacoma, Wash.

Editorial and Graphics

Mary S. Ashman, Technical Editor, U.S. Geological Survey, Northborough, Mass.

Jennifer L. Bruce, Geographer, U.S. Geological Survey, Middleton, Wis.

Michelle M. Greenwood, Publications Unit Chief, U.S. Geological Survey, Middleton, Wis.

James L. Kennedy, Geographer, U.S. Geological Survey, Middleton, Wis.

David A. Saad, Hydrologist, Geographer, U.S. Geological Survey, Middleton, Wis.

Approving Official 

Angel Martin, Jr., Hydrologist, Reports Specialist, Urbana, Ill.
xiv
Nutrient Concentrations and Their Relations to the 

Biotic Integrity of Wadeable Streams in Wisconsin

Dale M. Robertson1, David J. Graczyk1, Paul J. Garrison2, Lizhu Wang3, Gina LaLiberte2, and 

Roger Bannerman4

Abstract

Excessive nutrient (phosphorus and nitrogen) loss 

from watersheds is frequently associated with degraded 

water quality in streams. To reduce this loss, agricultural 

performance standards and regulations for croplands and 

livestock operations are being proposed by various States. 

In addition, the U.S. Environmental Protection Agency 

is establishing regionally based nutrient criteria that can 

be refined by each State to determine whether actions are 

needed to improve a stream’s water quality. More confidence in the environmental benefits of the proposed performance standards and nutrient criteria will be possible with 

a better understanding of the biotic responses to a range of 

nutrient concentrations in different environmental settings. 

The U.S. Geological Survey and the Wisconsin 

Department of Natural Resources collected data from 240 

wadeable streams throughout Wisconsin to: 1) describe 

how nutrient concentrations and biotic-community 

structure vary throughout the State; 2) determine which 

environmental characteristics are most strongly related to 

the distribution of nutrient concentrations; 3) determine 

reference water-quality and biotic conditions for different 

areas of the State; 4) determine how the biotic community of streams in different areas of the State respond to 

changes in nutrient concentrations; 5) determine the best 

regionalization scheme to describe the patterns in reference 

conditions and the responses in water quality and the biotic 

community; and 6) develop new indices to estimate nutrient concentrations in streams from a combination of biotic 

indices. The ultimate goal of this study is to provide the 

information needed to guide the development of regionally 

based nutrient criteria for Wisconsin streams.

For total nitrogen (N) and suspended chlorophyll 

(SCHL) concentrations and water clarity, regional variability in reference conditions and in the responses in 

water quality to changes in land use are best described by 

subdividing wadeable streams into two categories: streams 

in areas with high clay-content soils (Environmental Phosphorus Zone 3, EPZ 3) and streams throughout the rest of 

the State. The regional variability in the response in total 

phosphorus (P) concentrations is also best described by 

subdividing the streams into these two categories; however, little consistent variability was found in reference P 

concentrations in streams throughout the State.

Reference P concentrations are similar throughout the 

State (0.03–0.04 mg/L). Reference N concentrations are 

divided into two categories: 0.6–0.7 mg/L in all streams 

except those in areas with high clay-content soils, where 

0.4 mg/L is more appropriate. Reference SCHL concentrations are divided into two categories: 1.2–1.7 μg/L in 

all streams except those in areas with high clay-content 

soils, where 1.0 μg/L may be more appropriate. Reference 

water clarity is divided into two categories: streams in 

areas with high clay-content soils with a lower reference 

water clarity (Secchi tube depth, SD, of about 110 cm) and 

streams throughout the rest of the State (SD greater than 

or equal to about 115 cm). For each category of the biotic 

community (SCHL and benthic chlorophyll a concentrations (BCHL), periphytic diatoms, macroinvertebrates, and 

fish), a few biotic indices were more related to differences 

in nutrient concentrations than were others. For each of the 

indices more strongly related to nutrient concentrations, 

reference conditions were obtained by determining values 

corresponding to the worst 75th percentile value from a 

subset of minimally impacted streams (streams having 

reference nutrient concentrations). 

By examining the biotic community in streams having either reference P or N concentrations but not both, the 

relative importance of these two nutrients was determined. 

For SCHL, P was the more important limiting nutrient; 

1

 U.S. Geological Survey, Wisconsin Water Science Center, 

Middleton, Wisconsin

2

 Wisconsin Department of Natural Resources, Monona, Wisconsin

3

 Michigan Department of Natural Resources, Ann Arbor, Michigan

4

 Wisconsin Department of Natural Resources, Madison, Wisconsin
however, for BCHL and all macroinvertebrate indices, it 

appears that N was the more important nutrient when concentrations were near reference concentrations. For other 

diatom indices and all fish indices, small additions of P or 

N appear to have little effect on these communities when 

nutrient concentrations are near reference conditions.

Concentrations of P and N in streams increase as 

the percentage of agricultural land increases. Concentrations of P increase more quickly and concentrations of N 

increase more slowly in response to increasing percentages 

of agriculture in areas with high clay-content soils than do 

streams in the rest of the State. The response in water clarity is similar in streams throughout the State; however, the 

streams in areas with high clay-content soils have poorer 

reference water clarity, and, therefore, as the percentage 

of agriculture increases, their clarity remains lower than in 

streams in areas with other soil types. 

As nutrient concentrations increase, many biotic indices change. This result indicates that these nutrients have 

direct or indirect effects on the composition of the biotic 

community. Thresholds were identified at which a small 

change in nutrient concentrations results in a relatively 

large change in the biotic communities. The thresholds in 

the response to changes in P concentrations range from 

about 0.04 mg/L for BCHL, to 0.06–0.07 mg/L for diatom 

and fish indices, to about 0.09 mg/L for macroinvertebrate indices. The thresholds in the response to changes 

in N concentrations range from 0.5 mg/L for the fish 

indices and one macroinvertebrate index to about 0.9–1.2 

mg/L for the diatom and other macroinvertebrate indices. 

Most of the biotic indices had a wedge-shaped response 

to increases in nutrient concentrations. At relatively low 

nutrient concentrations, the biotic indices ranged widely, 

but at relatively high concentrations, the indices generally 

were poor. The wedge-shaped distribution indicates that 

at low nutrient concentrations, factors other than nutrients 

often limit the health of biotic communities, whereas, at 

high nutrient concentrations, nutrients and factors correlated with high nutrient concentrations are the predominant 

factors.

The biotic communities that are present in a stream 

reflect the overall ecological integrity; therefore, they 

integrate the effects of many different stressors and thus 

provide a broad measure of their aggregate effect. Nutrient concentrations by themselves explained from about 6 

to 13 percent of the total variance in the components of 

the biotic communities or from about 14 to 23 percent of 

the explained variance. Nutrient concentrations were most 

important in affecting SCHL concentrations and macroinvertebrate communities, and least important in affecting 

BCHL, periphytic diatoms, and fish-community structure. 

For each component of the biotic community, nutrients 

by themselves only explained a small part of the overall 

variance; about half of the variance could not be explained 

by the variables examined in this study and about one-third 

of the explained variance could not be assigned to single 

categories of environmental characteristics. 

By use of a combination of four biotic indices, two 

new multiparameter indices (Biotic Index of total Phosphorus, BIP, and Biotic Index of total Nitrogen, BIN) were 

developed to estimate P and N concentrations in streams 

from biotic data collected in streams. These multiparameter models estimated high and low nutrient concentrations 

equally well. The BIP predicted P concentrations better 

than the BIN predicted N concentrations. The difference 

in the accuracy of these indices was consistent with biotic 

indices being more correlated with P concentrations than 

with N concentrations. This result suggests that P is more 

important than N in affecting most biotic communities as 

nutrient concentrations increase above reference concentrations.

Although specific mechanisms of how nutrients 

affect the biota in wadeable streams were not examined in 

this study, the results indicate that nutrients are important 

in controlling the biotic health of streams. Although the 

biotic-community structure represents the overall ecological integrity of the stream, nutrients alone explained only a 

small part of the variance in the biotic community. Therefore, it is difficult to predict the exact result of reducing 

nutrient concentrations without also modifying the factors 

typically associated with high nutrient concentrations. 

Nutrient concentrations in many streams, especially those 

in agricultural areas, are well above the concentrations 

where thresholds in the response were found to occur; 

therefore, small reductions in nutrient concentrations in 

these streams are not expected to have large effects on the 

biotic community. Even with these limitations, however, 

it is expected that reducing nutrient concentrations will 

improve the biotic community, further the beneficial 

ecological functioning of most streams, and improve the 

quality of downstream nutrient-limited receiving waters.

Introduction

 Elevated nutrient concentrations above background 

conditions are one of the most common stressors (contaminants) affecting streams throughout the United States. 

2 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Problems associated with elevated nutrient concentrations in surface water are not new, but they are among the 

most persistent. According to the National Water Quality 

Inventory: 1996 Report to Congress by the U.S. Environmental Protection Agency (USEPA), 50 States, Tribes, and 

other jurisdictions surveyed water-quality conditions in 

19 percent of the Nation’s 3.6 million miles of rivers and 

streams and found overenrichment of nutrients to be the 

second most common reason for impairment following 

the combined effects of suspended sediment and siltation 

(U.S. Environmental Protection Agency, 1996). Excessive 

nutrients in rivers and streams can result in the overgrowth 

of benthic algae in shallow areas and in areas with fast 

current and an overabundance of phytoplankton and macrophytes in deep areas with slow current. High algal and 

macrophyte biomass can cause severe diurnal fluctuations 

in dissolved oxygen and pH because of biotic production 

and respiration, and can generate harmful organic materials 

when part of the population dies (Welch and others, 1992). 

These conditions can lead to an increase in the availability 

of toxic substances, reduction in available aquatic habitat, 

modifications to the composition of the biotic communities, and a decrease in the overall usefulness of the stream 

(Miltner and Rankin, 1998; Dodds and Welch, 2000). 

Excessive transport of nutrients has also been linked to 

eutrophication of downstream lakes and impoundments, 

outbreaks of Pfiesteria in bays and estuaries in various 

Gulf and Mid-Atlantic States, and hypoxia in the Gulf of 

Mexico (U.S. Environmental Protection Agency, 2000a). 

Under recommendations of the Clean Water Action 

Plan released in 1998, the USEPA has developed a 

National strategy to develop waterbody-specific nutrient criteria for lakes and reservoirs, rivers and streams, 

wetlands, and estuaries (U.S. Environmental Protection 

Agency, 1998); this study is concerned with those for 

rivers and streams. The intent of this strategy is to get all 

States and tribes to establish nutrient standards, that, if 

enforced, will reduce nutrient concentrations and improve 

the beneficial ecological uses of surface waters. The best 

way to control nutrient concentrations is to reduce that part 

contributed by humans, not that part contributed naturally. 

It has been recognized that various environmental characteristics, such as land use, geology, soils, climate, and 

hydrology (including human modifications and hydrologic 

structures) are important in determining water quality 

(Monteith and Sonzogni, 1981; Clesceri and others, 1986; 

and Robertson, 1997). Because these characteristics vary 

greatly across the United States, the establishment of 

regional nutrient criteria makes scientific sense. 

Various frameworks have been used to divide large 

areas into smaller areas of relatively similar environmental 

characteristics to minimize the natural variation in water 

quality within the areas and maximize the differences 

among the areas. One such framework is the ecoregion 

delineation developed and refined by Omernik (1987; 

1995) and Omernik and others (2000). Ecoregions are a 

mapped-classification system of regions with assumed 

relative homogeneity in ecological characteristics. These 

regions were said to be defined on the basis of relative differences in a suite of environmental characteristics, such 

as land use/land cover, land-surface form, geology, physiography, climate, soils, potential natural vegetation, and 

other environmental characteristics (Omernik, 1987 and 

1995). The USEPA has taken the initial step in developing 

regional nutrient criteria based on combining Omernik’s 

84 level III ecoregions into 14 national nutrient ecoregions 

for the conterminous United States (U.S. Environmental 

Protection Agency, 1998; fig. 1). On a subregional basis, 

such as a specific State, each of these 14 nutrient ecoregions can be further subdivided into the original level III 

ecoregions. Wisconsin is subdivided into two national 

nutrient ecoregions (ecoregions 7 and 8; fig. 1), which are 

further subdivided into four primary level III ecoregions: 

Northern Lakes and Forests (NLF), North Central Hardwood Forests (NCHF), Southeastern Wisconsin Till Plains 

(SWTP), and the Driftless Area (DFA)(Omernik and 

others, 2000; fig. 2A). In addition, there are small pieces 

of the Western Cornbelt Plains and the Central Cornbelt 

Plains ecoregions. Because the Cornbelt Plains ecoregions 

represent only a small part of the State, they will not be 

discussed in this report. The nutrient ecoregions provide 

an initial classification scheme for developing nutrient 

criteria; however, the USEPA expects individual States and 

tribes to evaluate and possibly develop alternative regionalization schemes (U.S. Environmental Protection Agency, 

2000b).

The nutrient ecoregions proposed by the U.S. Environmental Protection Agency (1998) may define spatial 

patterns in water quality; however, this regionalization 

scheme has some inherent problems. Although the boundaries between ecoregions are supposed to represent the differences in a suite of related environmental characteristics 

(Omernik, 1995), specific boundary lines are often based 

on differences in a single environmental characteristic and 

that characteristic may not be the primary one affecting 

a specific water-quality characteristic. Therefore, greater 

variations in water quality may occur within an ecoregion than among ecoregions. Second, in defining most 

Introduction 3
6

6

8

8

8

9

7

7

7

1

11

11

11 0

0

250 500 KILOMETERS

250 125 MILES

CroplandCropland and pastureForestWetlandUrbanWater

EXPLANATION

Ecoregion

Corn Belt and Northern Great PlainsMostly Glaciated Dairy RegionGlaciated Upper Midwest and NortheastSoutheast Temperate Forested PlainsCentral/Eastern Forested Uplands

Land use/land cover

6789

11

102° 84°

45°

36°

Base from USGS digital line graphs

Figure 1. National nutrient ecoregions (U.S. Environmental Protection Agency, 1998) and major land uses in the upper Midwest (U.S. Geological Survey, 2000 and 2004).

4 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Environmental phosphorus zones

B. A.

1

Zones

2345

Mostly cropland

EXPLANATIONLand Use EXPLANATION

NorthCentralHardwoodForests(NCHF)

Northern Lakes and Forests

(NLF)

SoutheasternWisconsinTill Plains(SWTP)

Driftless Area

(DFA)

Mixed croplandMixed forestMostly forestUrbanWaterEcoregion boundary

Level III ecoregions

00

20 40 60 KILOMETERS

20 40 60 MILES

43°

46°

92°

88°

43°

46°

92°

88°

Figure 2. Two regionalization schemes considered for wadeable streams in Wisconsin: A, level III ecoregions (Omernik and others, 2000) with major land-use/land-cover 

categories (Lillesand and others, 1998) and B, environmental phosphorus zones (Robertson and others, 2006; described on page 6).

Introduction 5
ecoregions, the relative importance of each environmental 

characteristic is often unknown and can vary from one area 

of the country to another in an unknown way. Therefore, 

the differences in water quality among ecoregions can be 

difficult to attribute to any specific environmental characteristic. Finally, for many applications, such as establishing 

reference conditions for nutrient criteria, the environmental characteristics used to delineate regions of similar 

water quality should be restricted, as much as possible, to 

characteristics that are intrinsic, or natural, and are not the 

result of human activities (U.S. Environmental Protection 

Agency, 2000a). Here, “reference” water quality refers to 

background concentrations or the potential water quality 

that could be achieved in the absence of human activities. 

By comparing the lines delineating the ecoregions with the 

land-use patterns in figure 1, it is apparent, however, that 

land use was the most important characteristic in defining the ecoregions in the upper Midwest. Although the 

ecoregion delineation is supposed to represent differences 

in a full suite of environmental characteristics, nutrient 

ecoregions primarily subdivide the upper Midwest (and 

Wisconsin) into areas of forest, cropland and pasture, and 

cropland.

To overcome the problems just described with the 

USEPA’s nutrient ecoregions, SPARTA (SPAtial Regression-Tree Analysis) was developed to define characteristicspecific zones with similar reference water quality for the 

upper Midwest (Robertson and Saad, 2003) and refined 

to remove both the direct and indirect effects of land use 

(Robertson and others, 2006). There are two steps in the 

SPARTA process to delineate water-quality zones. The first 

step is to use regression-tree analysis (Breiman and others, 

1984) to describe the relations between a single dependent 

variable (for example, phosphorus (P) concentrations) and 

various independent variables (for example, clay content of 

the soil and basin slope) thought to affect the distribution 

of the dependent variable. The second step of SPARTA is 

to use the regression-tree results (specific characteristics 

and breakpoints) to divide the entire study area into zones 

representing each of the final branches of the analysis. 

To refine the SPARTA approach, land-use-adjusted 

(residualized) water-quality and environmental characteristics were computed and used to remove the direct and 

indirect effects of land use from the data for each site. 

Although SPARTA can be applied with only intrinsic or 

natural characteristics to remove the direct effects of land 

use as done by Robertson and Saad (2003), these natural 

characteristics themselves may be strongly correlated with 

land use. Thus, even if natural characteristics are the only 

factors included in the analysis, land use can be indirectly 

incorporated into the results. SPARTA was applied to the 

land-use-adjusted nutrient data and land-use-adjusted environmental-characteristic data for sites throughout the upper 

Midwest to develop environmental water-quality zones 

(Robertson and others, 2006). Because the biota in streams 

were assumed to be more influenced by P than by total 

nitrogen (N) concentrations, environmental P zones (EPZs) 

were examined as an alternative regionalization scheme 

for the wadeable streams of Wisconsin (fig. 3). The upper 

Midwest is divided into five EPZs based primarily on the 

clay content of the soil and secondarily on the slope of the 

terrain. Wisconsin consists of four major EPZs and one 

minor EPZ (fig. 2B). Streams in EPZ 1 have basins with 

the lowest clay content, streams in EPZ 2 have soils with 

moderate clay content and low-gradient terrain, streams in 

EPZ 3 have basins with high clay content and low-gradient 

terrain, and streams in EPZ 4 have basins with moderate 

clay content and steep terrain. Only a small part of EPZ 5 

(basins with high clay content, steep terrain, and high soil 

erodibility) is in Wisconsin and, therefore, is not examined 

in detail in this study. Each of these zones contain streams 

with relatively similar reference P concentrations and with 

P concentrations that should respond similarly to changes 

in land use. 

After relatively homogenous geographic areas are 

chosen, several approaches have been used to define quantitative nutrient criteria. The approach suggested by the 

USEPA to define possible criteria is based on the reference 

or potential water quality of each area. In other words, 

the criteria should be based on the conditions that are 

attainable in the geographic location of each stream (U.S. 

Environmental Protection Agency, 2000a). Reference 

concentrations for P, N, suspended chlorophyll a (SCHL, 

also referred to as sestonic chlorophyll), and turbidity have 

been defined from the frequency distribution of all available data (from USEPA’s Storage and Retrieval, STORET, 

database) for each area. It has been suggested that the 

lower 25th percentile of all concentration data for an area 

may represent this reference condition (U.S. Environmental Protection Agency, 2000b). In other words, 25 percent 

of all the sites have water quality at least as good as this 

reference condition. It has also been suggested that the 

upper (highest or worst) 75th percentile of the concentration data for a subset of streams thought to be minimally 

impacted for a defined area may represent this reference 

condition. In other words, 75 percent of the minimally 

impacted sites have water quality at least as good as this 

reference condition. The final criterion should be between 

6 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
these two concentrations. Another approach to estimate 

reference concentrations for each relatively homogeneous 

area is to develop a multiple linear-regression model that 

relates water quality to various anthropogenic factors or 

characteristics such as the percentages of agriculture and 

urban area in the watershed (Dodds and Oakes, 2004). 

With this approach, the estimated concentration of a 

constituent occurring in the absence of human activities 

(in other words, with 0-percent agricultural and 0-percent 

urban areas) represents the reference concentration. These 

relations or equations can also be used to place confidence 

intervals on the reference concentrations.

An alternative approach to defining the nutrient 

criteria is based on thresholds in the response between 

nutrient concentrations and biotic indices such as algal 

productivity (chlorophyll a concentration), water clarity, or 

diatom or fish biotic indices (U.S. Environmental Protection Agency, 2000a). The biotic community that is present 

in a stream, however, reflects more than just the nutrient 

concentrations that are or were present in the stream. The 

biotic community represents the overall ecological integrity of the stream (in other words, physical, chemical, and 

biological integrity), and thus provides a broad measure of 

the aggregate effect of all stressors (Barbour and others, 

1999). Biotic communities are controlled by many physical, chemical, and biological factors, though they may be 

directly affected by only a subset of variables. Watershed 

characteristics (such as geomorphology, geochemistry, 

and land use/land cover) control the physical/chemical 

habitat of the stream where the biota live (Frissell and 

others, 1986; Poff, 1997). Nutrients have been shown to 

directly affect the productivity and species composition 

of primary producers, such as macrophytes and benthic 

and suspended algae, and indirectly affect the primary 

and secondary consumers in controlled nutrient-enrichment experiments (for example, Mundie and others, 1991; 

Peterson and others, 1993; Perrin and Richardson, 1997); 

however, only limited studies have shown observational 

linkages between nutrients and the health of the biotic 

communities in natural streams. Among the limited studies in natural environments, Miltner and Rankin (1998) 

reported that macroinvertebrate- and fish-community 

indices were negatively correlated with N and P concentrations in wadeable streams in Ohio. Zorn (2003) reported 

that P was one of the important variables for predicting the 

presence or absence of specific fish species in Michigan 

streams. Heiskary and Markus (2003) also reported significant negative correlations between macroinvertebrate- and 

fish-community characteristics and P and N concentrations 

in nonwadeable rivers in Minnesota.

If relations between nutrient concentrations and 

biotic integrity are used to define criteria, the final nutrient 

Environmental

phosphorus zones

Zone

1

2

3

4

5

EXPLANATION

Base from USGS digital line graphs

0 100 200 MILES

0 100 200 KILOMETERS

102° 84°

45°

36°

Figure 3. Environmental phosphorus zones (EPZs) in the upper Midwest from Robertson and others (2006).

Introduction 7
criteria should be chosen to minimize degradation in the 

biotic integrity of the streams. In other words, the criteria 

should be the concentrations that would not result in high 

algal concentrations or degradation of other biotic indices. One of the difficulties in defining nutrient criteria is 

determining the chlorophyll a concentration or other biotic 

index values for which a stream is considered degraded or 

impaired. The assumption made with this biotic-response 

approach is that each of the subregions in a regional framework also delineates an area with streams whose biotic 

indices respond in a similar manner to changes in nutrients. Whichever approach is used, the final criteria must be 

stringent enough to protect the specific site and cause no 

adverse effects in downstream waters. 

Reference nutrient concentrations, the responses 

in nutrient concentrations to changes in land use, and 

the biotic responses to changes in nutrients may differ 

in streams throughout Wisconsin. There would be more 

confidence in the potential environmental benefits of 

enforcing nutrient criteria and standards for the State, if 

the criteria and standards were based on the most appropriate regionalization scheme (such as nutrient ecoregions 

or EPZs), and if the criteria and standards were based on 

the appropriate regionally defined thresholds to biotic 

response. Defined nutrient criteria and thresholds for 

responsive biotic indices would enable the use of monitoring data to identify streams affected by excessive nutrients 

and to direct rehabilitation efforts.

The two regionalization schemes being considered 

for the establishment of nutrient criteria for Wisconsin, 

level III ecoregions and EPZs, are shown in figure 2. 

The USEPA developed the preliminary criteria based on 

median concentrations of all the data measured at each site 

rather than mean concentrations, because a median value 

represents the concentration most frequently occurring 

in the stream, and a statistical summary based on median 

values reduces the effects of outliers and values reported as 

less than their respective detection limits. The USEPA has 

provided preliminary criteria for P, N, SCHL, and turbidity for the national nutrient ecoregions and most level III 

ecoregions (table 1). The proposed criteria by the USEPA 

for P, based on the 25th-percentile approach, are 0.033 

mg/L for national nutrient ecoregion 7 and 0.010 mg/L for 

national nutrient ecoregion 8 (same as the NLF ecoregion). 

The USEPA has refined the P criteria for level III ecoregions in national nutrient ecoregion 7: 0.029 mg/L for 

NCHF, 0.070 mg/L for DFA, and 0.080 for SWTP (U.S. 

Environmental Protection Agency, 2000b and 2001). 

Robertson and others (2006) estimated median 

reference P concentrations for the two major national 

ecoregions and four major EPZs in Wisconsin (fig. 2) by 

use of the multiple linear-regression approach (previously 

described). They found that median reference P concentrations for the two national nutrient ecoregions were similar, 

approximately 0.015–0.016 mg/L. They also found that 

the four major EPZs could be combined into two zones 

based on estimated reference P concentrations of 0.012 

mg/L for EPZ 1 and approximately 0.021–0.023 mg/L for 

EPZ 2, EPZ 3, and EPZ 4, and the four major EPZs could 

be combined into three zones based on the response of P 

concentrations to changes in land use: EPZ 1 was least 

responsive, EPZ 2 and EPZ 4 were moderately responsive, 

and EPZ 3 was most responsive. Streams in EPZ 3, with 

the highest clay content, had high reference P concentrations (similar to EPZs 2 and 4), but were the most responsive to changes in land use. 

Purpose and Scope

In 2001, the U.S. Geological Survey (USGS) and the 

Wisconsin Department of Natural Resources (WDNR), 

began a collaborative study to: 1) describe how the nutrient 

concentrations and biotic-community structure in streams 

differ throughout Wisconsin; 2) determine which environmental characteristics of watersheds are most strongly 

related to the distribution of nutrient concentrations in 

streams; 3) determine reference water-quality and biotic 

conditions for different areas of the State; 4) determine 

how the biotic community of streams in different areas of 

the State respond to changes in nutrient concentrations; 

5) evaluate existing regionalization schemes in terms of 

describing patterns in reference water-quality conditions 

and patterns in biotic response to changes in nutrient 

concentrations; and 6) develop new multiparameter biotic 

indices to predict nutrient concentrations in streams. The 

ultimate goal of this study is to provide the information 

needed to guide the development of regionally based nutrient criteria for streams in Wisconsin.

Because the biotic response in streams was expected 

to vary as a function of stream size, and wadeable streams 

are sampled with different techniques than nonwadeable 

streams, the study was divided into two parts. The first part 

involved sampling 240 wadeable streams in 2001–03, and 

the second part involved sampling approximately 40 nonwadeable streams in 2003. In this report, the results of the 

first part of this study are presented: nutrient concentrations and their relations to the biotic integrity of wadeable 

streams in Wisconsin. The second part of the study will be 

presented in a separate report.

8 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 1. Reference concentrations for total phosphorus, total nitrogen, and suspended chlorophyll a, and turbidity in selected 

national nutrient and level III ecoregions (U.S. Environmental Protection Agency, 2000b and 2001) and environmental phosphorus 

zones (EPZs) from Robertson and others (2006).

[USEPA, U.S. Environmental Protection Agency; NCHF, North Central Hardwood Forests; DFA, Driftless Area; SWTP, Southeastern Wisconsin Till 

Plains; --, no data; NTU, nephelometric turbidity units; FTU, formazin turbidity units; mg/L, milligram per liter; μg/L, microgram per liter]

Region USEPA

criteria

Reference concentration based on Robertson and others (2006) 

Median Standard error Upper 95-percent 

confidence limit

25th percentile 

of all sites

Total phosphorus (mg/L)

Ecoregion 7 0.033 0.016 0.003 0.024 0.040

 NCHF-51a .029 -- -- -- --

 DFA-52a .070 -- -- -- --

 SWTP-53a .080 -- -- -- --

Ecoregion 8 .010 .015 .002 .019 .010

EPZ 1 -- .012 .002 .017 .020

EPZ 2 -- .021 .003 .026 .030

EPZ 3 -- .021 .004 .030 .060

EPZ 4 -- .023 .003 .030 .050

Total nitrogen (mg/L, calculated/reported)

Ecoregion 7 0.54/0.54 -- -- -- --

 NCHF-51a .46/.71 -- -- -- --

 DFA-52a 1.88/1.51 -- -- -- --

 SWTP-53a 1.59/1.30 -- -- -- --

Ecoregion 8 .20/.38 -- -- -- --

Turbidity (NTU/FTU)

Ecoregion 7 1.7/2.32 -- -- -- --

 NCHF-51a .84/2.14 -- -- -- --

 DFA-52a 3.38/2.4 -- -- -- --

 SWTP-53a --/2.74 -- -- -- --

Ecoregion 8 .81/1.3 -- -- -- --

Chlorophyll a (μg/L, fluorometric/spectrophotometric/trichromatic methods)

Ecoregion 7 1.54/3.50/5.8 -- -- -- --

 NCHF-51a 1.03/8.76/-- -- -- -- --

 DFA-52a 1.00/2.32/-- -- -- -- --

 SWTP-53a .55/3.52/-- -- -- -- --

Ecoregion 8 .60/2.60/4.3 -- -- -- --

a

 USEPA level III ecoregion identification numbers

Introduction 9
Approach

Because simultaneously collected hydrological, 

water-quality, and biological data were not available to 

determine how the biotic integrity of Wisconsin streams 

is related to changes in nutrient concentrations, a network 

of streams was selected to represent the wadeable and 

nonwadeable streams in the level III ecoregions and EPZs 

in the State. Although some level III ecoregions were 

combined into larger-scale national nutrient ecoregions 

and some of the EPZs were combined because there were 

no statistical differences in reference concentrations or in 

the responses to changes in land use among some zones 

in the upper Midwest study (Robertson and others, 2006), 

each of the level III ecoregions and EPZs were examined 

separately in this study. The locations of the 240 wadeable streams are shown in figure 4 and listed in appendix 

1. To try to obtain streams that represent the range in 

environmental conditions in Wisconsin, approximately 

the same number of sites was chosen in each of the level 

III ecoregions. To try to obtain streams with a wide range 

in nutrient concentrations, sites in each ecoregion were 

chosen to try to represent a full range in the percentage 

of agricultural land, although this was not always possible. Discharge and water quality of each stream were 

sampled monthly over a 6-month period (May through 

October). Benthic (attached) algae and diatoms were 

sampled once during the period. During 2001, 157 streams 

with the smallest watersheds were sampled (2.2 to 222 

km2

, but generally less than 90 km2). During 2002, 78 

larger streams were sampled (40 to 1,947 km2). In 2003, 

42 nonwadeable streams (not discussed in this report) and 

five additional wadeable streams were sampled (11 to 106 

km2). Data on macroinvertebrate and fish populations were 

not collected as part of this study, but were available from 

past surveys. A prerequisite for site selection was that the 

macroinvertebrate and fish populations in the stream had 

been sampled during the past 5 years. 

For each site, the drainage basin was digitized and a 

geographic information system (GIS) was used to describe 

the environmental characteristics of the watershed. Various 

multivariate statistical approaches were then used to determine how the environmental characteristics of the watershed were related to water quality and biotic-community 

structure. The data were used to determine which stratification scheme (level III ecoregions or EPZs) best describes 

the distributions in reference nutrient concentrations and 

the responses in nutrient concentrations to changes in land 

use. Reference concentrations of P, N, and SCHL, and 

water clarity were estimated by use of the multiple linearregression approach and the 25th-percentile approach for 

the best regionalization scheme. Reference values for the 

biotic indices were estimated by use of the 75th-percentile 

approach by examining the values of the biotic indices at 

minimally impacted sites (sites with nutrient concentrations at or below the estimated reference concentrations). 

Water-quality data were statistically compared with biotic 

indices describing the suspended and benthic algae, diatoms, macroinvertebrates, and fish to determine how the 

biotic integrity of streams is related to changes in nutrient 

concentrations, and whether or not thresholds in P and (or) 

N concentrations can be defined above which the biology 

is adversely affected. Two new multiparameter indices 

were then developed to estimate P and N concentrations in 

streams on the basis of the biotic-community structure.

Methods of Data Collection and 

Analysis

Field Methods

Discharge, Water Chemistry, and Suspended 

Chlorophyll a Concentrations

Streamflow and water quality in each stream were 

sampled monthly over a 6-month period (May through 

October). Each site was sampled near the middle of the 

month regardless of flow conditions. During each visit, 

discharge and field parameters (specific conductance, 

water temperature, dissolved oxygen, and pH) were either 

measured or estimated and a water-quality sample was 

collected. 

Discharge was determined at each site with a current 

meter (Rantz and others, 1982), with a stage/discharge 

relation for a continuous-recording gaging station at the 

site, or estimated from a nearby site. If the site was not 

wadeable because of high flow and did not have a continuous-recording gage, the discharge was estimated from 

a nearby streamflow-gaging station by use of relations 

between previous discharge measurements at the site and 

at the nearby station.

Specific conductance, water temperature, dissolved 

oxygen, pH, and, at some sites, turbidity were measured 

in the field at the time of sampling by use of a multiparameter meter. The meters were calibrated each day 

before use. Water clarity was measured by use of a 120-cm 

10 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
EXPLANATION

Site and identification 

number

Selected city

209

MADISON

MILWAUKEE

STEVENS

POINT

STEVENS

EAU CLAIRE POINT GREEN

BAY

Base map from U.S. Geological Survey 

digital data, 1:2,000,000.

3

1

2

8 9

10

15

28

29

220

52

53

54

55

56

218 217

62

221

58

60

57

59

30

17

19

20

21

18

14

13 12

13

253

255

256

16

219

252

251

249

250

4

6 5

254

7

238

24 27

36

47

48 49

50

223

222

224

301

302

68

69

67

73

229

230

70

303

228

61 225

226

227

71 72

65 63 64

66

74

214 76

77 86

212

110

81

210

209

89

87

88

90 207

208

106

121 104

105 211

103

205

203 204 122

201 98

93

91

206

92

94

97

96 95

202

108

109

107

102

85 79

83

84 78

80 75

215

216

82

213

23

22

45

46

248

39 40

42 41

43

239

240 237

241

32

242

33

34

231

232

304

35

287277 275

274

136

271

273

138

270 139 272

134

131

129

130

128

157

267

113

116

112

118

258

257 123

124

125 126

156

155

127

114 115

111

117

144 143 145

264

266

147

146

265 148 151 149 150 263

262

152

158 153 154

261

51

99

101

100

260 259

119

120

133 132

269 141 140

142

268

137

135

276

236

305

233

234

235

37 38

31 245 247

244 246

243

25

26

0

0 20 40 60 KILOMETERS

20 40 60 MILES

44°

45°

43°

46°

92°

91°

90°

89°

88°

87°

Figure 4. Sites on wadeable streams in Wisconsin included in this study. Water-quality and biotic data for each site are given by 

site identification number in the appendixes. 

Methods of Data Collection and Analysis 11
Secchi tube (also referred to as a transparency tube, U.S. 

Environmental Protection Agency, 2004). The Secchi tube 

was held into the flowing stream and filled. The tube was 

then held perpendicular to the ground and drained until the 

Secchi disk at the bottom of the tube became visible. The 

water level in the tube was read to the nearest centimeter 

and defined as the Secchi tube depth (SD). If the disk was 

visible when the tube was full, the value was reported as 

greater than 120 cm.

All water samples were collected by use of the 

equal-width-increment (EWI) method with a hand-held 

DH-59 depth-integrating sampler (Edwards and Glysson, 

1999), except when stream conditions were not appropriate (stream velocity less than approximately 0.45 m/s, 

maximum depth less than 0.15 m, or the stream was 

nonwadeable); in this case, a grab sample was collected 

with an open bottle at the center of the flow. Samples were 

then split into appropriate bottles for lab analysis. Samples 

to be analyzed for dissolved constituents were filtered in 

the field through 0.45-μm membrane filters. Samples to 

be analyzed for SCHL were obtained by filtering a known 

volume of water through a 5-μm membrane filter. The 

filter was then placed in a labeled petri dish and wrapped 

in aluminum foil. All samples were chilled until they were 

delivered to the Wisconsin State Laboratory of Hygiene for 

analysis, except samples to be analyzed for SCHL, which 

were frozen, kept in the dark, and delivered to the WDNR 

Research Laboratory. All samples were analyzed for P, 

dissolved phosphorus (DP), total Kjeldahl nitrogen (TKN), 

dissolved nitrite plus nitrate nitrogen (NO3

-N), dissolved 

ammonia nitrogen (NH4-N), and SCHL. In July of 2002, 

samples were also collected for analysis of suspended 

sediment. All chemical analyses of water samples (except 

SCHL) were done by the Wisconsin State Laboratory of 

Hygiene in accordance with standard analytical procedures 

described in the “Manual of Analytical Methods, Inorganic 

Chemistry Unit” (Wisconsin State Laboratory of Hygiene, 

1993). At the WDNR Research Laboratory, the filters for 

SCHL analysis were placed in tubes containing 90 percent 

acetone, stored at least 24 hours, sonicated for 15 minutes, 

and stored an additional 24 hours in a freezer. The trichromatic chlorophyll a content of the samples was determined 

by means of a USEPA-approved method (Greenberg and 

others, 1992). Throughout this report, the water-chemistry, 

water-clarity, and SCHL data are collectively referred to as 

“water-quality data.” All water-quality data were input into 

the USGS National Water Information System (NWIS) 

(U.S. Geological Survey, 1998).

Benthic Chlorophyll a and Diatoms

Samples for benthic chlorophyll a (BCHL) and 

periphytic-diatom analyses were collected once during 

August or September. Care was taken to avoid collecting samples within 2 weeks of appreciable rainfall to 

minimize the potential effect of scouring. Samples were 

collected by brushing a known area of three to five rocks 

with a toothbrush. Following collection, the samples were 

placed on ice and kept in the dark. Within 12 hours of 

sampling, the sample was diluted to a known volume with 

distilled water, homogenized in a blender, and a portion 

was filtered through two 3–5 μm glass-fiber filters. One 

filter was placed in 90 percent acetone and was analyzed 

for its acid-corrected chlorophyll a content (BCHL) by 

means of a USEPA-approved monochromatic method 

(Greenburg and others, 1992). The other filter was used for 

the determination of ash-free dry weight. This sample was 

dried overnight at 105oC and ashed at 550oC for 1 hour. 

The sample was weighed before and after ashing. Because 

of either lack of suitable substrate or lack of water at the 

time of collection, BCHL samples were collected from 

only 199 sites.

The sample for microscopic analysis of the diatom 

assemblage was obtained from a portion of the homogenized sample used for BCHL analysis; however, if rocks 

were not available, samples were collected from sticks. 

The sample was preserved with Lugols solution and 

cleaned with hydrogen peroxide and potassium dichromate 

(van der Werff, 1955). A portion of the diatom suspension 

was dried on a cover slip and mounted in Naphrax. Specimen were identified and counted under an oil-immersion 

objective (1,400 or 1,750X). At least 300 diatoms were 

counted from two slides in each sample. The keys used to 

identify the species included Patrick and Reimer (1966, 

1975), Camburn and others (1984–86), Dodd (1987), 

and Krammer and Lange-Bertalot (1986, 1988, 1991a,b). 

Because of either lack of coarse substrate or lack of water 

at the time of collection, samples were collected from only 

214 sites.

Physical Habitat and Fish 

Physical-habitat and fish data were collected by the 

WDNR once at each site between 1997 and 2002. The 

physical habitat was determined for a stream length equal 

to 35 times the mean stream width, or a minimum of 

100 m. This length is generally sufficient to encompass 

about three meander sequences (Simonson and others, 

12 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
1994; Wang and others, 1996). The physical habitat and 

fish were quantified between late May and late August 

when low flows facilitated effective sampling and largescale seasonal fish movement was unlikely to occur 

(Lyons and Kanehl, 1993). At each site, 30 physical-habitat characteristics, including channel morphology, bottom 

substrates, cover, bank conditions, riparian vegetation, 

and land cover were measured or visually estimated along 

12 transects by use of standard procedures (Simonson 

and others, 1994). The entire length of each site was 

electrofished with either two backpack units in tandem 

or a single tow-barge unit with three anodes (Lyons and 

Kanehl, 1993; Simonson and Lyons, 1995). Efforts were 

made to collect all of the fish greater than or equal to 25 

cm in length. All captured fish were identified to species, 

counted, and weighed in aggregate by species.

Macroinvertebrates 

Macroinvertebrate samples were collected by the 

WDNR once at each site between 1999 and 2002. Two 

types of macroinvertebrate samples were collected according to procedures described by Hilsenhoff (1988). Samples 

were generally collected from each site during low flow 

in early October by use of a 600-μm mesh D-frame kick 

net. The first sample was collected from riffles or rocky 

substrates. If rocky substrates were not present, then vegetative snags (areas with overhanging grasses, logs, woody 

debris, and leaf packs) were sampled to ensure that the 

sample was from the most representative habitat at each 

site. The second sample was collected only from snags to 

ensure that these data were comparable between all sites 

because rocky substrates were not always present.

Samples from riffle or rocky substrates were collected by placing the net on the stream bottom and kicking 

an area immediately upstream of the net to dislodge the 

macroinvertebrates and wash them into the net. In addition, individual rocks were picked up and the attached 

macroinvertebrates were removed and added to the sample. 

This process was repeated in at least three locations within 

the same riffle or different riffles until at least 200–300 

organisms were collected. Samples were collected in snags 

by placing a net in the water column downstream of the 

snag, where it would collect most of the dislodged debris. 

The snags were then disturbed by scraping or shaking 

them with a net, hands, or feet. At each site, all available 

snag types at multiple locations were sampled, with first 

consideration given to larger snags in higher water-velocity 

habitats.

Samples were sorted and identified at the laboratory 

of Dr. Stanley Szczytko at the University of Wisconsin, 

Stevens Point. The samples were placed in a glass pan 

positioned over a 6.5-cm2 grid. All of the organisms 

from randomly chosen grid squares were selected until a 

minimum of 125 organisms having tolerance values cited 

in the literature (such as the values in Hilsenhoff, 1988) 

were picked, or, until the entire sample was sorted. All of 

the picked organisms were counted and identified to the 

species or the lowest taxonomic level possible. 

Watershed Boundaries and Environmental 

Characteristics

Watershed boundaries for the sampled streams were 

manually digitized from 1:24,000-scale USGS topographic 

quadrangle maps. The environmental characteristics 

thought to affect the water quality and biology in the 

streams were compiled for each watershed used in this 

study: land use/land cover (Lillesand and others, 1998); 

soil characteristics (from the USSOILS digital coverage of 

the State Soil Geographic, STATSGO, data base; Schwarz 

and Alexander, 1995); types of surficial deposits (Fullerton 

and others, 2003); annual air temperature and precipitation 

(National Climatic Data Center, 2002); mean land-surface 

slope (based on 30-m DEM data resampled to 100 m; 

U.S. Geological Survey, 1999); and average annual runoff 

(Gebert and others, 1987).

Point-source loadings of phosphorus upstream of each 

sampling site (PtS) were estimated from monthly mean 

P concentrations and monthly mean discharge volumes 

as reported by the dischargers (for example, wastewatertreatment plants and cheese factories) in their Discharge 

Monitoring Report with the WDNR (James Baumann, 

Wisconsin Department of Natural Resources, written commun., 2004). The number of concentrations and discharge 

volumes reported in a month varied with the size and type 

of discharger and ranged from one sample per month to 

daily samples. For sites where P concentrations were not 

required to be measured and, therefore not reported, the P 

concentrations were estimated based on the size and type 

of discharger.

All basin characteristics were compiled in digital 

form by use of a GIS. A digital coverage of each watershed was used to compute the average or percentage value 

for each environmental characteristic, including the PtS 

for each of the 240 watersheds. A summary of the environMethods of Data Collection and Analysis 13
mental characteristics (with the specific metric describing 

each environmental characteristic) for all of the watersheds 

used in this study is given in table 2. 

Data Summaries

All of the water-quality data collected in this study 

were input into the USGS NWIS database (U.S. Geological Survey, 1998) and are summarized in appendix 1. In 

computing summary statistics, all of the data were used 

regardless of whether or not flow could be detected. During some samplings, the water in the streams was found to 

have dried up, and no water-quality data were collected. 

All data reported as less than the detection limit were set 

to one-half of the detection limit, and all SD data greater 

than 120 cm were set to 120 cm prior to any statistical and 

graphical analyses.

Physical-habitat data were summarized into: mean 

wetted width, depth, thalweg depth, and stream gradient; 

the percentage of the stream reach with riffles, runs, or 

pools; the mean depth of sediment; the percentage of the 

bottom of the stream reach composed of different substrates, embedded rocky substrate, and covered by algae 

or macrophytes; the percentage of the stream reach that 

contains fish cover, is shaded, and that has streambank 

erosion; and buffer width (Simonson and others, 1994). 

The physical-habitat data for each site are summarized in 

appendix 2.

Three metrics were used to summarize the diatomcommunity data: the Diatom Nutrient Index (DNI), the 

Diatom Siltation Index (DSI; Bahls, 1992), and the Diatom 

Biotic Index (DBI). The DNI computations are based on 

tolerance values assigned to individual taxa. DNI values 

range from 1 to 6, with 1 representing species typically 

found with the lowest nutrient concentrations (oligotrophic, good water quality) and 6 typically representing 

species found with the highest nutrient concentrations 

(hypereutrophic, poor water quality). The values for Wisconsin diatoms (appendix 3) were generated largely from 

Van Dam and others (1994), but values were also assigned 

based upon experience with the diatom communities in 

Wisconsin. If no autecological data were known, the taxa 

were not assigned a value and were not included in the 

DNI calculation. Because the index is based upon relative 

abundance, rare species have little effect on the final index 

value. The formula used to calculate DNI value is

(1),

where

 ni = number of individuals of species i;

 ti = tolerance-index value for species i; 

 j = total number of species in the sample with 

tolerance-index values; and

 N = total number of individuals in the sample 

having tolerance-index values.

The second metric for the diatom community is the 

Diatom Siltation Index (DSI). This index is based on the 

sum of all individuals in the Navicula (including Cavinula, 

Chamaepinnularia, Craticula, Diadesmis, Fallacia, Fistulifera, Geissleria, Hippodonta, Kobayasiella, Luticola, 

Mayamaia, Placoneis, and Sellaphora), Nitzschia (including Psammodictyon and Tryblionella), and Surirella taxa. 

These taxa were chosen because they have good motility; 

therefore, this metric reflects the degree of siltation in a 

reach (Bahls, 1992). The scale for the index is 0–100 with 

lower values indicating less silt and thus better water quality.

To assess stream biotic integrity, a multimetric index 

called the Diatom Biotic Index (DBI) was created. The 

DBI is based on both diatom indices, DNI and DSI. For 

computing the DBI, each metric was standardized to the 

95th percentile for a number of reference sites and then 

the two metrics were averaged. For sites with an individual 

metric exceeding its 95th percentile, the metric was set to 

100. The scale of the DBI is 0 to 100, with higher values 

indicating better biotic integrity. The DBI is intrinsically 

designed to be sensitive to nutrient enrichment and the 

effects of sedimentation. The reference sites used to standardize the metric were chosen by combining the northern 

ecoregions (NLF, NCHF) and the southern ecoregions 

(DFA, SWTP). Reference sites for the southern ecoregions 

were those where P concentrations for August were less 

than or equal to 0.050 mg/L. For the southern ecoregions, 

there were 13 reference sites and 105 sites with P concentrations exceeding 0.050 mg/L. Reference sites for the 

northern ecoregions were sites with less than or equal to 

10-percent agriculture in the watershed. For the northern 

ecoregions, there were 42 reference sites and 55 sites with 

more than 10-percent agriculture.

Six common measures were used to summarize the 

macroinvertebrate data: the Hilsenhoff Biotic Index (HBI; 

Hilsenhoff, 1988) and five other macroinvertebrate indices 

based on the percentage or total number of individuals of 

various groups or species that were counted in the samples 

(for example, Ohio Environmental Protection Agency, 

DNI = 

N

ni t 3 i i = 1

j

14 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 2. Summary statistics for median monthly water-quality and environmental (anthropogenic/land-use, basin, soil, and 

surficial-deposit) characteristics of the watersheds of the sites in the studied wadeable streams in Wisconsin.

[mg/L, milligram per liter; log, logarithm to base 10 transformation; μg/L, microgram per liter; C, Celsius; μS/cm, microSiemen per centimeter; cm, centimeter; (m3

/s)/km2, cubic meter per second per square kilometer; km2, square kilometer; mm, millimeter; mm/year, millimeter per year; --, unitless; %, 

percent; mm/hr, millimeter per hour; kg/km2, kilogram per square kilometer; >, greater than; no PtS, only sites with less than 12 kg/km2 of point-source 

loading of phosphorus are included in this part of the analysis; summary statistics based on monthly values] 

Characteristic Unit Transformation Count Median Mean Standard 

deviation Minimum Maximum

Water-quality characteristics

Total phosphorus mg/L log 240 0.085 0.116 0.144 0.012 1.641

Total phosphorus (no PtS) mg/L log 234 .082 .105 .097 .012 .741

Dissolved phosphorus mg/L log 240 .050 .079 .122 .004 1.495

Dissolved phosphorus (no PtS) mg/L log 234 .050 .069 .074 .004 .553

Total nitrogen mg/L log 240 1.695 2.807 2.860 .131 21.260

Dissolved nitrite plus nitrate mg/L log 240 1.048 2.086 2.865 .005 20.550

Dissolved ammonia mg/L log 240 .029 .039 .044 .007 .040

Total Kjeldahl nitrogen mg/L log 240 .563 .675 .414 .070 2.350

Suspended chlorophyll a μg/L log 240 2.27 3.23 4.06 .40 38.01

Water temperature C none 240 15.7 15.5 2.0 9.3 21.6

Specific conductance μS/cm none 240 478 455 284 27 1,405

Secchi tube deptha cm none 240 112.0 97.3a 28.9 23.5 >120

Flow per unit area (m3

/s)/km2 log 240 .007 .009 .011 .001 .122

Anthropogenic/land-use characteristics

Urban % none 240 .00 .01 .01 .00 .14

Agriculture (row crops) % none 240 .20 .24 .21 .00 .78

Agriculture (other) % none 240 .20 .19 .15 .00 .57

Total agriculture % none 240 .46 .42 .31 .00 .94

Grassland % none 240 .09 .10 .08 .00 .39

Wetland (open) % none 240 .02 .04 .06 .00 .48

Wetland (forested) % none 240 .03 .07 .10 .00 .85

Barren % none 240 .01 .02 .02 .00 .21

Forest (all) % none 240 .31 .40 .31 .01 .99

Point-source loading of phosphorus kg/km2 log 240 .00 1.47 6.44 .00 73.62

Basin characteristics

Watershed area km2 log 240 26.4 121.9 261.8 2.2 1947.1

Air temperature C none 240 6.9 6.5 1.4 3.7 9.2

Precipitation mm none 240 837 836 37 743 926

Runoff mm/yr none 240 229 246 50 152 366

Basin slope degrees none 240 5.92 6.85 3.49 1.35 16.04

Soil characteristics

Clay content % none 240 18.10 19.07 10.58 3.43 41.80

Erodibility -- none 240 .28 .26 .07 .11 .40

Organic-matter content % none 240 3.83 5.19 5.06 .30 31.02

Permeability mm/hr none 240 58.32 84.57 66.41 16.00 307.71

Soil slope % none 240 6.03 7.49 4.59 1.02 23.03

Surficial-deposit characteristics

Nonglacial deposits % none 240 .00 .23 .41 .00 1.00

Clay % none 240 .00 .12 .30 .00 1.00

Loam % none 240 .00 .08 .26 .00 1.00

Peat % none 240 .00 .01 .04 .00 .42

Sand % none 240 .26 .37 .40 .00 1.00

Sand and gravel % none 240 .01 .19 .28 .00 1.00

a

 All values greater than 120 cm were set to 120 cm for computation of summary statistics, which result in the mean values being biased low.

Methods of Data Collection and Analysis 15
1988; Kerans and Karr, 1994; Barbour and others, 1999; 

and Weigel, 2003). The HBI is an abundance-weighted 

tolerance index based on the tolerance of each macroinvertebrate taxon to organic pollution and dissolved oxygen 

depletion. HBI values range from 0 to 10, with higher 

values indicating more degraded water quality. The five 

other macroinvertebrate indices included the percentage 

of individuals that were either Ephemeroptera, Plecoptera, 

or Trichoptera (EPTN%), the percentage of taxa that were 

Ephemeroptera, Plecoptera, or Trichoptera (EPTTX%), the 

percentage of individuals that were scrapers (SCRAP%), 

the percentage of individuals that were shredders 

(SHRED%), and the total number of taxa (TAXAN). For 

each site, each of these indices was computed for the riffle 

and snag samples separately, and then an average value 

was computed. The macroinvertebrate indices for each site 

are summarized in appendix 4.

Eight community measures were computed to summarize the fish data. Two measures described the quantity 

of fish caught: total number of fish caught (FISHN) and 

total number of species caught (FISHSPEC). Five indices described feeding and tolerant classifications: the 

percentages of top carnivores (CARN%), insectivores 

(INSECT%), and omnivores (OMNI%), and the percentages of pollution-tolerant (TOL%) and pollution-intolerant 

(INTOL%) fish (based on Lyons, 1992; and Lyons and 

others, 1996). In addition, the fish Index of Biotic Integrity 

(IBI) score was computed by use of both the cold-water 

(Lyons and others, 1996) and warm-water (Lyons, 1992) 

versions. Because all of the sites were not classified as a 

warm-water, cool-water, or cold-water fishery and a coolwater version of the IBI is not available for Wisconsin, the 

higher of the two IBI scores was used as the site’s fish IBI 

value. The use of different versions of the IBI compensates 

for different fish assemblages in different thermal regimes. 

Differences in the other fish indices represent broad feeding and pollution-tolerance classifications; therefore, the 

metrics in streams with very different species are comparable. The fish metrics for each site are summarized in 

appendix 4.

Statistical Methods

The SAS statistical software package (SAS Institute, 

Inc., 1989) was used for all statistical analyses except 

for the redundancy analyses, which were done with the 

CANOCO statistical software package (ter Braak and 

Smilauer, 2002), and the regression-tree analyses, which 

were done with the SPLUS statistical software package 

(Lam, 2001).

Normalization

Before statistical analyses, all water-quality data 

except the SD data were logarithmically transformed (base 

10) to improve the normality of the data. This transformation improved the normality of the data although not 

always to the 5-percent-significance level (Shapiro-Wilk 

normality test). In addition, all chlorophyll a data, pointsource data, and watershed areas were logarithmically 

transformed prior to statistical analyses.

Correlations and Regressions 

Spearman correlation analyses were used to determine the relation between each water-quality characteristic 

and biotic index and each environmental characteristic. 

This nonparametric procedure was chosen to reduce the 

influence of the assumption of normal-data distributions. 

Sequential Bonferroni tests were used to determine the 

statistical significance of the correlations to eliminate the 

effects of the number of tests on the significant level (Rice, 

1989). Pearson correlation analyses were also used to 

determine the relation between each water-quality characteristic and each environmental characteristic prior to the 

use of multiple regressions and forward stepwise-regression analysis (with p < 0.05 as the critical level for entry). 

This procedure was used to determine the magnitude of 

the interaction between environmental characteristics and 

water-quality characteristics, as well as to determine the 

best multivariate relation to estimate concentrations at a 

specific site as a function of the environmental characteristics in its watershed.

Simultaneous Partial Residualization

Many studies (such as Robertson and others, 2006, 

and this study), have shown that land use not only directly 

affects water quality, but it is often strongly correlated with 

the environmental characteristics used to define regions of 

similar water quality (indirect effects of land use). Therefore, in order to determine the relation between water quality and the nonanthropogenic or natural characteristics, a 

simultaneous partial-residualization approach, related to 

partial correlation, was used to remove the agricultural and 

urban effects from the concentrations of P and N and from 

the measures of each of the environmental characteristics. 

16 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
In simple regression, the relation between the dependent variable Y (for example, P) and a predictor variable 

X1 (for example, the clay content of the soil in the basin) 

can be measured by the sample correlation rYX1. If the 

variable X1 is regressed on the variable X2 (for example, 

the percentage of agricultural area), the estimated regression equation X1, 2 = β0

 + β1X2 would be obtained. To 

adjust X1 for the effects of X2, a “residualized X1”, X1

*

, 

can be obtained by computing X1

*

 = X1 – X1,2. In a manner 

similar to simple correlation, the strength of the relation 

between Y and X1 adjusted for X2 (in this case, land use) 

can be obtained by the correlation between the residuals 

for Y on X2 (Y*) and the residuals for X1 on X2 (X1

*

). The 

resulting correlation is the partial correlation of Y and X1

adjusted for X2; the strength of the relation between Y and 

X1

 has been adjusted for the effects of X2. This approach, 

described by Weisberg (1980), is easily extended to control 

for more than one variable; X2 can be replaced by an 

arbitrary set of variables. In this study, the residualization 

approach was used to remove the effects of the percentages 

of agriculture and urban areas and PtS (logarithmically 

transformed point-source loading in the basin) to enable 

the relations between the dependent variables P, N, SCHL, 

and SD and all of the nonanthropogenic environmental 

characteristics to be further examined. This approach was 

not used to examine relations between environmental characteristics and the biotic indices. Spearman correlations 

and forward stepwise regressions were done with raw data 

and with residualized data to determine which environmental characteristics best described the distribution of 

each water-quality characteristic.

Regression-Tree Analysis

In traditional linear-regression analysis, a continuous 

dependent variable is assumed to be a linear function of a 

set of independent variables. This is often an unrealistic 

assumption, and departures from linearity can result in 

underestimating, or completely discounting, important 

independent variables. Although departures from linearity can be addressed to some extent by trial-and-error data 

transformations, this approach becomes problematic when 

independent variables interact in multiple dimensions. The 

method of regression-tree analysis (Breiman and others, 

1984) prevents these problems by not incorporating the 

assumptions about the shapes of the relations between a 

dependent variable and one or more independent variables. 

Regression-tree analysis sequentially partitions the values 

of each independent variable into two groups, computes 

mean values of the dependent variable for each group, and 

then computes square errors for each partition. At each 

step, all of the independent variables are scanned, and the 

independent variable and its breakpoint that minimize the 

least-square-error criterion are chosen. In a manner similar 

to the F-statistic in an analysis of variance, the leastsquare-error criterion is used to identify breakpoints that 

maximize the variance of the interpartition means relative 

to the intrapartition variance. This process partitions the 

independent-variable space into increasingly homogeneous 

regions (branches on a tree). The end result of this sequential process is a branching diagram. If only one independent variable is used (for example, the concentration of 

P or N) at each step in the analysis, the best breakpoint 

for the independent variable is defined as the value which 

subdivides values of the dependent variable (for example, 

IBI) into the two groups with the maximum difference in 

their mean values. This breakpoint represents the threshold 

in the response of the dependent variable.

Regression-tree analyses were done with various 

dependent variables (SCHL, SD, and various biotic indices) and the corresponding independent variables (nutrient 

concentrations) to determine breakpoints or thresholds in 

the responses of the dependent variables to changes in specific nutrient concentrations. In the analysis, the minimum 

number of sites used to define a subgroup was set to 25 to 

avoid creating small outlier groups. Regression-tree analysis was also used to determine the value (threshold) below 

which PtS had minimal effect on P concentrations. 

Redundancy Analysis

Redundancy analysis (RDA) is a form of direct-gradient analysis that describes the variation between two 

mul tivariate data sets (for example, water-quality and environmental characteristics; ter Braak and Prentice, 1988). In 

RDA, the site scores from a principal-component analysis 

are regressed on a specified set of environmental characteristics, and the fitted values of the regression become new 

site scores for the following iteration; therefore, the principal component analysis is constrained by the environmental variables (Jongman and others, 1987). RDA was used 

in this study to quantify the variance in the dependent variables (for example, water-quality characteristics) explained 

by the independent variables (for example, environmental 

characteristics) and to determine which environmental 

characteristics best explained the variance in water quality. 

Methods of Data Collection and Analysis 17
In addition, partial RDA (Richards and others, 1996) was 

used to determine the fraction of the variance in the waterquality characteristics explained by specified categories of 

the environmental characteristics (such as land-use, basin, 

and soil/surficial-deposit characteristics), and to determine 

the fraction of the variance in populations of specified 

groups of the biotic community (such as benthic chlorophyll a concentrations and populations of diatoms, macroinvertebrates, and fish) explained by specified categories 

of environmental characteristics (such as nutrient characteristics and environmental characteristics). Monte Carlo 

permutation tests with 99 iterations, the default number of 

iterations in CANOCO, were used to determine the validity of the total and partial RDA results. Monte Carlo tests 

were done by permutating the assignment of the independent (environmental) data to the dependent (water-quality 

or biological) data randomly and repeating the ordinations 

(Richards and others, 1996; Johnson and others, 1997). 

Statistical Differences among Groups

To determine whether any apparent differences 

among groupings of data (such as reference sites compared 

to nonreference sites) were statistically significant, the 

nonparametric Kruskal-Wallis rank analysis of variance 

test was used, fol lowed by a Tukey multiple-comparison 

procedure (SAS Institute, Inc., 1989). For all statistically 

significant differ ences, the probability of their occurring 

by chance was less than 5 percent (p < 0.05), unless otherwise specified. 

18 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Median monthly concentrations of total P ranged 

from 0.012 to 1.641 mg/L (table 2 on page 15). The 

overall median and mean were 0.085 and 0.116 mg/L, 

respectively. Highest concentrations were measured in the 

central part of the State, especially south of Green Bay 

(fig. 5). High concentrations were also measured in the 

southwestern part of the State. The lowest P concentrations 

were measured in the northern one-third of the State. The 

highest P concentrations were measured in June and July, 

and the lowest concentrations were measured in October 

(table 3). 

Median monthly concentrations of DP ranged from 

0.004 mg/L (less than the 0.005 mg/L detection limit) to 

1.495 mg/L (table 2). The overall median and mean were 

0.050 and 0.079 mg/L, respectively. The distribution and 

seasonality in DP concentrations were similar to total P 

concentrations (table 3). DP concentrations were strongly 

correlated to total P concentrations. Pearson correlation 

coefficients (r values) between DP and P ranged from 0.90 

in June to 0.98 in September. DP represented about 53 to 

62 percent of the phosphorus during May through July and 

about 70 percent during August through October. 

Median monthly concentrations of N ranged from 

0.131 to 21.260 mg/L (table 2). The overall median and 

mean were 1.695 and 2.807 mg/L, respectively. The highest median N concentrations were measured in the southern quarter of the State and the eastern half of the State 

(fig. 5). The lowest N concentrations were found in the 

northern quarter of the State. The highest N concentrations 

were measured in June, but no consistent seasonal patterns 

were measured (table 3). 

Median monthly concentrations of NO3

-N ranged 

from 0.005 mg/L (less than the 0.010 mg/L detection limit) 

to 20.550 mg/L (table 2). The overall median and mean 

were 1.048 and 2.086 mg/L, respectively. Median monthly 

concentrations of NH4-N ranged from 0.007 mg/L (less 

than the 0.013 mg/L detection limit) to 0.040 mg/L. The 

overall median and mean were 0.029 and 0.039 mg/L, 

respectively. Median monthly concentrations of TKN 

ranged from 0.070 mg/L (less the 0.140 mg/L detection 

limit) to 2.350 mg/L. The overall median and mean were 

0.563 and 0.675 mg/L, respectively. Most of the nitrogen 

was in the form of NO3

-N (ranging from 63 percent in 

June to 73–79 percent in other months). Highest NO3-N 

Water Quality and Its Relations with Environmental 

Characteristics in the Watershed

Water Quality and Its Relations with Environmental Characteristics in the Watershed 19

U.S. Geological Survey personnel collecting streamflow measurements.
Total phosphorus (P)

0.012 – 0.038

Concentrations,

in milligrams per liter

Concentrations,

in milligrams per liter

Depth, in centimeters

Concentrations,

in micrograms per liter

0.039 – 0.066

0.067 – 0.103

0.104 – 0.162

0.163 – 1.641

0.404 – 1.44

1.45 – 1.99

2.00 – 2.56

2.57 – 3.80

3.81 – 38.01

0.131 – 0.735

0.736 – 1.361

1.362 – 2.245

2.246 – 4.500

4.501 – 21.260

24 – 67

68 – 102

103 – 119

r120

Total nitrogen (N)

Suspended chlorophyll a

(SCHL)

Secchi tube depth

(SD)

Figure 5. Distributions (quintiles) of median monthly total phosphorus (P), total nitrogen (N), and suspended chlorophyll a

concentrations (SCHL), and Secchi tube depth (SD) for the studied wadeable streams in Wisconsin. (Note: the upper 40 percent of

SDs were all greater than or equal to 120 centimeters.)

20 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
and TKN concentrations were measured in June, but no 

consistent seasonal patterns were measured in any form of 

nitrogen. 

Median monthly concentrations of SCHL ranged from 

0.40 to 38.01 μg/L (table 2). The overall median and mean 

were 2.27 and 3.23 μg/L, respectively. Highest SCHL 

concentrations were measured in the central and eastern 

parts of the State, especially south of Green Bay and north 

of Milwaukee (fig. 5). Lowest SCHL concentrations were 

measured in the northern one-third of the State and in the 

southwestern part of the State. Highest SCHL concentrations were measured in July, and lowest concentrations 

were measured in September and October (table 3). 

Median monthly SDs ranged from 23.5 cm to greater 

than 120 cm (table 2). Many sites consistently had clarities greater than the length of the Secchi tube. The overall 

median and mean were 112 and 97.3 cm, respectively. 

Highest SDs (the best clarities) were measured in the northern half of the State (fig. 5). Lowest SDs (the worst clarities) were measured in the southwestern and central parts 

of the State and south of Green Bay. Lowest SDs were 

measured during May through July, and the highest SDs 

were measured during August through October (table 3).

Relations between Water Quality and 

Environmental Characteristics in the 

Watershed 

Correlations between Individual 

Characteristics

Spearman correlation coefficients (rs values) between 

median water-quality characteristics are shown in table 

4. P and DP were significantly correlated with N, NO3-N, 

NH4-N, and TKN (rs values ranged from 0.36 to 0.61). 

Correlations between P and the nitrogen species were 

slightly stronger than between DP and the nitrogen species. Concentrations of N were strongly correlated 

(rs = 0.91) to NO3-N because NO3-N was the major form 

of nitrogen. Concentrations of NH4

-N and TKN were 

more strongly correlated to one another (rs = 0.66) and 

to P (rs ~ 0.6) than they were to total N and NO3-N (rs ~ 

0.1–0.3). NH4-N is part of TKN; therefore, a correlation 

between these two forms of nitrogen was expected. Total 

organic nitrogen was computed by subtracting the NH4-N 

concentration from the TKN concentration. Total organic 

nitrogen and NH4-N were still strongly correlated with one 

Table 3. Median and average monthly concentrations for total and dissolved phosphorus, suspended chlorophyll a, total 

nitrogen, nitrite plus nitrate, ammonia, and Kjeldahl nitrogen, and Secchi tube depths in the studied wadeable streams in 

Wisconsin.

[mg/L, milligram per liter; μg/L, microgram per liter; cm, centimeter; >, greater than; all concentrations are in mg/L, except chlorophyll a, which is in 

μg/L, and Secchi tube depth, which is in cm] 

Total phosphorus Dissolved phosphorus Chlorophyll a Secchi tube depth

Month Median Average Median Average Median Average Median Average

May 0.070 0.115 0.037 0.071 2.890 4.420 105.0 89.8

June .107 .164 .058 .101 2.120 3.120 88.5 79.6

July .092 .143 .052 .089 3.042 7.885 90.0 82.9

August .088 .138 .059 .096 2.168 5.096 > 120 92.9

September .075 .120 .049 .085 1.773 3.336 > 120 101.1

October .049 .101 .035 .070 1.546 2.922 > 120 107.9

Total nitrogen Nitrite plus nitrate Ammonia Kjeldahl nitrogen

Month Median Average Median Average Median Average Median Average

May 1.589 2.919 0.911 2.120 0.030 0.061 0.700 0.800

June 2.110 3.949 1.120 2.500 .033 .049 .790 .949

July 1.740 2.851 .903 2.083 .032 .067 .560 .768

August 1.573 2.634 .788 1.919 .031 .062 .525 .715

September 1.622 2.750 .987 2.115 .031 .060 .510 .650

October 1.657 2.834 1.080 2.229 .027 .046 .470 .606

Water Quality and Its Relations with Environmental Characteristics in the Watershed 21
Table 4. Spearman correlation coefficients (rs) between median concentrations of total phosphorus, dissolved phosphorus, total nitrogen, nitrite plus nitrate, ammonia, total

Kjeldahl nitrogen, median Secchi tube depths, suspended chlorophyll a concentrations, percentages of urban and agricultural areas, point-source loadings of phosphorus, and 

specific environmental (anthropogenic/land-use, basin, soil and surficial-deposit) characteristics for the studied wadeable streams in Wisconsin.

[P, total phosphorus; DP, dissolved phosphorus; N; total nitrogen; NO3-N, nitrite plus nitrate; NH4-N, ammonia; TKN, total Kjeldahl nitrogen; SD, Secchi tube depth; SCHL, suspended chlorophyll a

concentration; % Urb, percentage of urban area; % Ag, percentage of agricultural area; PtS, point-source loading of phosphorus in kilograms per square kilometer; <, less than; no PtS, only sites with less than 12 kilograms per square kilometer of point-source loading of phosphorus are included in analysis; all values with an absolute value greater than 0.22 are statistically significant at p < 0.05; all values with an absolute value greater than 0.4 are in bold] 

Characteristic P P (no PtS) DP DP (no PtS) N NO3-N NH4-N TKN SD SCHL % Urb % Ag PtS

Water-quality characteristics

Total phosphorus 1.00 1.00 0.95 0.95 0.54 0.38 0.61 0.56 -0.57 0.44 0.14 0.67 .29

Dissolved phosphorus 0.95 0.95 1.00 1.00 .51 .36 .55 .52 -.48 .35 .11 .63 .27Total nitrogen .54 .52 .51 .50 1.00 .91 .29 .19 -.55 .31 .28 .81 .19

Dissolved nitrite 

plus nitrate

.38 .37 .36 .35 .91 1.00 .11 -.12 -.42 .18 .29 .77 .18

Dissolved ammonia .61 .61 .55 .56 .29 .11 1.00 .66 -.48 .35 -.02 .34 -.02

Total Kjeldahl 

nitrogen

.56 .55 .52 .52 .19 -.12 .66 1.00 -.38 .45 .04 .25 .08

Suspended 

chlorophyll a

.44 .43 .35 .34 .31 .18 .35 .45 -.40 1.00 .25 .45 .29

Secchi tube depth -.56 -.55 -.48 -.46 -.55 -.42 -.47 -.38 1.00 -.40 -.26 -.55 -.23

Anthropogenic/land-use characteristics

Urban .14 .08 .11 .05 .28 .29 -.02 .04 -.26 .25 1.00 .20 .49Agriculture 

(row crops)

.65 .65 .60 .59 .81 .73 .37 .33 -.55 .46 .23 .94 .20

Agriculture (other) .56 .56 .56 .56 .61 .63 .22 .04 -.37 .31 .16 .80 .22Total agriculture .67 .67 .63 .63 .81 .76 .34 .25 -.55 .45 .20 1.00 .21

Grassland .02 .03 .03 .04 .17 .25 -.02 -.19 .07 -.07 .21 .00 .08Wetland (open) .07 .06 .03 .02 -.10 -.23 .18 .48 -.04 .21 .18 -.10 .18Wetland (forested) -.22 -.21 -.21 -.20 -.52 -.66 .08 .47 .27 -.04 -.10 -.52 -.08

Barren .34 .32 .29 .27 .37 .33 .14 .22 -.23 .40 .33 .46 .17

Forest (all) -.64 -.63 -.58 -.58 -.83 -.75 -.38 -.30 .57 -.47 -.27 -.94 -.21

Point-source loading 

of phosphorus

.29 .22 .27 .19 .19 .18 -.02 .08 -.23 .29 .49 .21 1.00

22 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Characteristic P P (no PtS) DP DP (no PtS) N NO3-N NH4-N TKN SD SCHL % Urb % Ag PtS

Basin characteristics

Watershed area -0.07 -0.07 -0.08 -0.09 -0.06 -0.02 -0.23 -0.04 0.03 0.21 0.28 -0.04 0.51Air temperature .50 .47 .44 .42 .76 .74 .29 .09 -.55 .30 0.25 0.76 0.15

Precipitation .07 .04 .05 .02 .27 .36 -.07 -.32 -.17 .03 0.20 0.14 0.02Runoff -.48 -.48 -.43 -.43 -.60 -.59 -.36 -.19 .41 -.25 -0.24 -0.62 -0.16

Basin slope .19 .20 .22 .23 .17 .31 .00 -.39 -.14 -.15 -0.05 0.23 0.03Flow per unit area -.21 -.20 -.17 -.16 -.17 -.13 -.13 -.18 .15 -.16 -0.04 -0.25 -0.18

Soil characteristics

Clay content .52 .53 .52 .52 .58 .58 .24 .04 -.54 .22 0.14 0.73 0.15

Erodibility .54 .55 .55 .55 .57 .55 .21 .15 -.47 .35 0.11 0.76 0.12

Organic matter 

content

-.34 -.36 -.35 -.36 -.38 -.51 -.05 .33 .17 .01 0.02 -0.40 -0.05

Permeability -.53 -.54 -.54 -.56 -.46 -.44 -.21 -.09 .48 -.21 -0.05 -0.63 -0.09

Soil slope -.31 -.32 -.30 -.30 -.21 .01 -.35 -.68 .28 -.34 -0.06 -0.30 -0.04

Surficial-deposit characteristics

Nonglacial deposits .03 .02 .03 .02 .26 .36 -.11 -.45 -.17 -.01 0.05 0.22 0.09

Clay .26 .28 .24 .25 .09 .04 .21 .31 -.29 .20 0.06 0.31 0.16Loam .23 .26 .22 .25 -.04 -.07 .07 .18 .04 -.01 -0.02 0.06 0.15Peat -.06 -.06 -.08 -.07 -.14 -.20 .09 .17 -.08 .07 -0.05 -0.20 0.05Sand -.13 -.14 -.14 -.15 -.16 -.24 -.04 .20 .12 .08 0.05 -0.22 -0.05Sand and gravel -.42 -.44 -.43 -.45 -.34 -.33 -.13 .07 .23 -.08 0.13 -0.42 0.05

Table 4. Spearman correlation coefficients (rs) between median concentrations of total phosphorus, dissolved phosphorus, total nitrogen, nitrite plus nitrate, ammonia, total

Kjeldahl nitrogen, median Secchi tube depths, suspended chlorophyll a concentrations, percentages of urban and agricultural areas, point-source loadings of phosphorus, and 

specific environmental (anthropogenic/land-use, basin, soil and surficial-deposit) characteristics for the studied wadeable streams in Wisconsin—Continued.

[P, total phosphorus; DP, dissolved phosphorus; N; total nitrogen; NO3-N, nitrite plus nitrate; NH4-N, ammonia; TKN, total Kjeldahl nitrogen; SD, Secchi tube depth; SCHL, suspended chlorophyll a

concentration; % Urb, percentage of urban area; % Ag, percentage of agricultural area; PtS, point-source loading of phosphorus in kilograms per square kilometer; <, less than; no PtS, only sites with less than 12 kilograms per square kilometer of point-source loading of phosphorus are included in analysis; all values with an absolute value greater than 0.22 are statistically significant at p < 0.05; all values with an absolute value greater than 0.4 are in bold] 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 23
another (rs

 = 0.62). Concentrations of P and DP were also 

significantly correlated with the PtS in the basin (rs ~ 0.3). 

The six streams with PtS values higher than 12 kg/km2

had some of the highest measured P (ranging from 0.17 to 

1.64 mg/L) and DP concentrations (ranging from 0.098 to 

1.49 mg/L). Annual PtS below 12 kg/km2 had little effect 

on the concentrations of P and DP in the streams (on the 

basis of results from regression-tree analyses and graphical 

examination of the data). Omitting the six streams with PtS 

greater than 12 kg/km2 from the analyses, however, had 

little effect on the correlations with the other characteristics (table 4).

Spearman correlation coefficients between the 

water-quality characteristics and each environmental 

characteristic (anthropogenic/land-use, basin, soil, and 

surficial-deposit characteristics) are also shown in table 

4. All water-quality characteristics were significantly correlated with many environmental characteristics; however, 

they were most strongly correlated with characteristics 

describing land use (presence of agriculture or absence 

of forest), basin characteristics describing air temperature 

and runoff from the watershed, and the soil characteristics 

(clay content, erodibility, and permeability). In general, 

N (and NO3-N) and P (and DP) were correlated with the 

same environmental characteristics; however, the correlations with N concentrations were generally stronger than 

with P concentrations. Concentrations of NH4-N and TKN 

were less strongly correlated with the nonanthropogenic 

or natural environmental characteristics than the other 

water-quality characteristics. Concentrations of NH4-N 

were most strongly correlated with runoff and soil slope 

(rs ~ -0.35) and concentrations of TKN were most strongly 

correlated with soil slope (rs = -0.68). 

Concentrations of SCHL were significantly correlated 

with all but one of the nutrient constituents (the exception 

is NO3

-N with rs = 0.18). Concentrations of SCHL were 

most strongly correlated with TKN and P (rs ~ .45), less 

strongly correlated with NH4-N, DP, and N (rs = 0.31 to 

r

s

 = 0.35), and insignificantly correlated with NO3-N 

(rs = 0.18). Concentrations of SCHL were significantly 

correlated with most environmental characteristics; however, they were most strongly correlated with land-use 

characteristics (positively correlated with the percentage 

of total agriculture and negatively correlated with the 

percentage of forest), basin characteristics describing the 

air temperature and runoff from the watershed, and soil 

properties in the watershed (erodibility and soil slope). 

SDs were most strongly correlated with many of the same 

characteristics as SCHL; however, SDs were more strongly 

correlated with most characteristics, especially more correlated with N, NO3

-N, clay content, and runoff. Similar 

results were obtained if only sites with SDs less than 120 

cm were included in the analysis; however, the correlation 

coefficients were slightly smaller. 

Correlations with Individual Characteristics 

after Removing Relations with Anthropogenic 

Characteristics

Many of the environmental characteristics were 

strongly correlated with the anthropogenic characteristics 

(characteristics describing the land use and PtS in the 

basin), primarily the percentage of agriculture in the basin, 

and less strongly with the percentage of urban area and the 

PtS in the basin (table 4). Many of the nonanthropogenic 

or natural characteristics were also strongly correlated 

with the anthropogenic characteristics. For example, air 

temperature and runoff were correlated with the percentage 

of agriculture (rs values of 0.76 and -0.62, respectively). 

Therefore, even if the anthropogenic characteristics were 

not included in further statistical analyses, their effects 

could be incorporated into the final results by use of characteristics such as air temperature.

To examine the relations between the nonanthropogenic characteristics and the water-quality characteristics 

further, the relations between the anthropogenic characteristics (percentages of agriculture, Ag %, and urban, Urb 

%, areas in the basin and the PtS in the basin) and P, N, 

SCHL, and SD were removed by use of simultaneous partial-residualization. Residualized P, N, and SCHL concentrations and SDs were computed with equations 2–9:

Log PRes = Log PMeasured – Log PPredicted , (2)

where

 Log PPredicted = -1.448 + 0.744 Ag % – 

1.101 Urb % + 0.267 Log(PtS) (3)

 R2

 = 0.49;

Log NRes = Log NMeasured – Log NPredicted , (4)

where

 Log NPredicted = -0.247 + 1.112 Ag % + 

3.830 Urb % + 0.045 Log(PtS) (5)

 R2 = 0.68;

Log SCHLRes = Log SCHLMeasured – Log SCHLPredicted , (6)

where

 Log SCHLPredicted = 0.182 + 0.383 Ag % – 

0.860 Urb % + 0.260 Log(PtS) (7)

 R2 = 0.26;

24 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
SDRes = SDMeasured – SDPredicted , (8)

where

 SDPredicted = 119.6 – 47.371 Ag % – 

227.5 Urb % + 8.039 Log(PtS) (9)

 R2

 = 0.30.

Residual transformations were also applied to all of 

the other water-quality and environmental characteristics.

Spearman correlation coefficients between the residualized values for the water-quality characteristics and the 

residualized values for the environmental characteristics 

are shown in table 5. Residualized concentrations and SDs 

were still significantly correlated with many residualized 

environmental characteristics; however, they were not as 

strongly correlated. PRes and DPRes concentrations were 

most strongly correlated with residualized permeability of 

the soil, residualized soil slope, and residualized sand-andgravel surficial deposits. Basins with more permeable soils 

had lower PRes concentrations. NRes concentrations were 

most strongly correlated with various basin characteristics 

(residualized air temperature, precipitation, and runoff) 

and residualized clay content of the surficial deposits. 

Highest NRes concentrations occurred in areas with warmer 

air temperatures, more precipitation, lower runoff, and 

lower clay content in the surficial deposits. Highest 

NO3-NRes concentrations also occurred in these areas, especially if the areas had steep slopes. Highest TKNRes concentrations occurred where NO3

-NRes concentrations were 

the lowest. Residualized SCHL concentrations were most 

strongly correlated with the slopes of the terrain and the 

soils, organic-matter content, and some surficial-deposit 

characteristics. Lowest SCHLRes concentrations occurred 

in areas with steep terrain and high organic-matter content. 

Residualized SDs were most strongly correlated with the 

clay content of the soil and surficial deposits; the best 

water clarity occurred in areas with low clay content. 

Thresholds in Water-Quality Responses

Concentrations of P and N were significantly correlated with the percentage of agriculture in the watershed. To define these relations better, logarithmically 

transformed P and N concentrations were plotted against 

the percentage of agriculture in the watershed (fig. 6), 

and regression-tree analyses were done to determine the 

percentages of agriculture that were the best breakpoints 

or thresholds in the responses. Regression-tree results 

indicate that the best statistically significant (p < 0.001) 

breakpoints in the responses of P and N to percentages 

of total agriculture were at 14.1 and 21.3 percent, respectively. In both cases, however, the relations between P and 

N concentrations and the percentage of agriculture appear 

linear and the line determined with linear regression better 

defined the response than a step change in values (on the 

basis of a mean-square-error criterion).

Concentrations of SCHL were significantly correlated 

with P and N concentrations (tables 4 and 5). To better 

define these relations, logarithmically transformed SCHL 

concentrations were plotted against logarithmically transformed P and N concentrations (fig. 7) and regression-tree 

analyses were done. Regression-tree results indicate that 

the best breakpoint in the response of SCHL to changes 

in P concentration was at 0.070 mg/L (log P = -1.16) and 

to changes in N concentrations occurred at 1.169 mg/L 

(log N = 0.07); both breakpoints were statistically significant at p < 0.001. The relations between SCHL and P 

and N concentrations appear linear and the regression line 

defines the response better than a step change in median P 

concentrations; however, the step-change response better 

defines the relation with N (on the basis of a mean-squareerror criterion). A similar response was found between P 

and SCHL in temperate streams, with the greatest increase 

in SCHL occurring at P concentrations less than 0.1 mg/L

(Van Nieuwenhuyse and Jones, 1996).

To define the relations between SDs and P and N 

concentrations better, SDs were plotted against logarithmically transformed P and N concentrations (fig. 7) 

and regression-tree analyses were done. There was little 

apparent relation between SDs and P and between SDs and 

N at lower nutrient concentrations because of the limited 

length of the Secchi tube; however, with higher nutrient 

concentrations, SDs gradually decreased. Regression-tree 

results indicate that the best breakpoint in the response 

of SDs to changes in P concentrations was at 0.106 mg/L 

(log P = -0.97) and to changes in N concentrations was at 

3.305 mg/L (log N = 0.52); both breakpoints were statistically significant at p < 0.001. A regression line defines 

the response better than a step change for P and N (on 

the basis of a mean-square-error criterion). The reduction 

in SDs with increasing nutrient concentrations may have 

been caused by other factors that are correlated to P and 

N concentrations, such as the clay content of the soils and 

surficial deposits (table 4).

Water Quality and Its Relations with Environmental Characteristics in the Watershed 25
Table 5. Spearman correlation coefficients (rs

) between residualized logarithmically transformed median concentrations of total 

phosphorus, dissolved phosphorus, nitrogen, nitrite plus nitrate, total Kjeldahl nitrogen, ammonia and suspended chlorophyll a, 

median Secchi tube depths, and specific residualized environmental (basin, soil, and surficial-deposit) characteristics for the

studied wadeable streams in Wisconsin.

[PRes, residualized total phosphorus; DPRes, residualized dissolved phosphorus; NRes residualized nitrogen; NO3-NRes, residualized nitrite plus nitrate; 

NH4-NRes. residualized ammonia; TKNRes, residualized total Kjeldahl nitrogen; SDRes, residualized Secchi tube depth; SCHLRes, residualized suspended 

chlorophyll a concentration; all values with an absolute value greater than 0.18 are statistically significant at p < 0.05; all statistically significant values 

(not including relations between nutrients) are in bold] 

Residualized characteristic PRes DPRes NRes NO3-NRes NH4-NRes TKNRes SDRes SCHLRes

Residualized water-quality characteristics

Total phosphorus 1.00 0.91 -0.02 -0.29 0.58 0.55 -0.26 0.22

Dissolved phosphorus .91 1.00 .00 -.22 .50 .48 -.15 .07

Total nitrogen -.02 .00 1.00 .55 .09 .01 -.15 -.11

Dissolved nitrite plus nitrate -.29 -.22 .55 1.00 -.22 -.56 .14 -.30

Dissolved ammonia .58 .50 .09 -.22 1.00 .63 -.31 .28

Total Kjeldahl nitrogen .55 .48 .01 -.56 .63 1.00 -.25 .40

Suspended chlorophyll a .22 .07 -.11 -.30 .28 .40 -.18 1.00

Secchi tube depth -.26 -.15 -.15 .14 -.31 -.25 1.00 -.18

Residualized basin characteristics

Watershed area -.18 -.19 -.06 .03 -.22 -.05 .09 .14

Air temperature -.08 -.09 .24 .43 .00 -.27 -.06 -.10

Precipitation -.07 -.06 .22 .36 -.12 -.37 -.05 -.03

Runoff -.10 -.08 -.18 -.41 -.18 .04 -.07 .03

Basin slope .01 .07 .01 .33 -.09 -.48 .01 -.32

Flow per unit area -.05 -.01 .09 .13 -.06 -.16 .06 -.08

Residualized soil characteristics

Clay content .08 .15 -.11 .02 -.04 -.19 -.28 -.13

Erodibility .13 .19 -.09 -.02 -.08 -.12 -.02 .00

Organic-matter content -.11 -.16 -.09 -.44 .08 .41 -.13 .23

Permeability -.28 -.34 .06 .01 -.02 .06 .14 .07

Soil slope -.20 -.19 .06 .39 -.23 -.61 .09 -.24

Residualized surficial-deposit characteristics

Nonglacial deposits -.18 -.13 .16 .28 -.19 -.50 -.02 -.19

Clay .12 .12 -.27 -.34 .10 .27 -.22 .06

Loam .12 .11 -.09 -.13 .03 .11 .05 -.06

Peat .06 .03 .07 -.03 .08 .09 -.04 .04

Sand .05 -.01 .03 -.21 .04 .28 .02 .25

Sand and gravel -.31 -.33 -.01 -.02 -.03 .14 .04 .07

26 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
y = 0.79x - 1.44

R2 = 0.44

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

0 10 20

14.1 percent

30 40 50 60 70 80 90 100

PERCENTAGE OF TOTAL AGRICULTURAL LAND USE IN BASIN

LOG (TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER) LOG (TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

y = 1.13x - 0.23

R2 = 0.66

-1.0

-0.5

0.0

0.5

1.0

1.5

0 10 20

21.3 percent

30 40 50 60 70 80 90 100

PERCENTAGE OF TOTAL AGRICULTURAL LAND USE IN BASIN

Figure 6. Total phosphorus and total nitrogen concentrations as a function of the percentage of total agriculture in the 

watersheds of the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. 

Linear-regression lines and coefficients of determination (R2

) are given on each graph. 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 27
Suspended chlorophyll 

a concentration

y = 0.37x + 0.79

 R2 = 0.20

-0.5

2.01.51.00.50.0

-2.0 -1.5 -1.0 -0.5 0.0 0.5

LOG (MEDIAN TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER)

, IN MICROGRAMS PER LITER) A LOG (CHLOROPHYLL 

, IN MICROGRAMS PER LITER) A LOG (CHLOROPHYLL 

Secchi tube depth 

y = -41.69x + 51.28

R2 = 0.28 0

80604020

120100

-2.0 -1.5 -1.0 -0.5 0.0 0.5

LOG (MEDIAN TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER)

SECCHI TUBE DEPTH, IN CENTIMETERS

SECCHI TUBE DEPTH, IN CENTIMETERS

Suspended chlorophyll 

a concentration

y = 0.23x + 0.32

 R2 = 0.10

-0.5

2.01.51.00.50.0

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (MEDIAN TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

Secchi tube depth 

y = -35.48x + 106.14

R2 = 0.28 0

80604020

120100

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (MEDIAN TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

-1.16 (0.070 mg/L) 0.07 (1.169 mg/L)

0.52 (3.305 mg/L) -0.97 (0.106 mg/L)

Figure 7. Suspended chlorophyll a (SCHL) concentrations and Secchi tube depths (SDs) as a function of median total phosphorus and total nitrogen concentrations (logarithm 

to base 10 transformation) for the studied wadeable streams in Wisconsin. Linear-regression lines and coefficients of determination (R2) are given on each graph. 

28 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Effects of Multiple Environmental 

Characteristics on Water Quality

Stepwise Regression 

Forward stepwise regressions were done with all of 

the environmental characteristics to determine which three 

environmental characteristics best described the variance 

in P, N, and SCHL concentrations and SDs, done with only 

the nonanthropogenic (natural) characteristics to determine 

which of these characteristics best described the variance, and done with residualized characteristics (whose 

correlations with anthropogenic characteristics had been 

removed) best described the variance in the water-quality 

characteristics. Models with more than three variables did 

not significantly increase the amount of variance explained 

(accumulative R2 values). 

The percentage of total agriculture was the first variable incorporated into the model explaining variability in P 

concentrations; the second and third variables were log PtS 

and the percentage of loam deposits in the basin, respectively (table 6). Collectively, this model explained 56 

percent of the variance in P concentrations. If the anthropogenic characteristics were omitted from the analysis, the 

erodibility of the soil was the first variable incorporated 

into the model, runoff was second, and the percentage of 

loam deposits was third. This model explained 44 percent 

of the variance. After the characteristics were adjusted 

to remove the anthropogenic effects, residualized loam 

deposits became the first variable incorporated into the 

model, residualized sand-and-gravel deposits was second, 

and residualized nonglacial deposits was third. This model 

collectively explained 19 percent of the variance in PRes. 

The difference in the amount of variance explained by the 

first two regression models was caused by the removal of 

the effects of the anthropogenic characteristics that were 

not correlated with other environmental characteristics in 

the second model. The large difference in the amount of 

variance explained by the last two regressions was caused 

by the removal of all of the effects of the anthropogenic 

characteristics, including the independent (direct) effects 

and correlated (indirect) effects on the other variables. 

The percentage of total forest in the basin was the 

first variable incorporated into the model explaining variability in N concentrations, precipitation was the second, 

and the percentage of row crops in the basin was the 

third. Collectively, this model explained 72 percent of the 

variance in N concentrations. If the anthropogenic characteristics were omitted from the analysis, air temperature 

was the first variable, soil slope was the second, and the 

clay content of the soil was the third. After the characteristics were adjusted to remove the anthropogenic effects, 

residualized clay deposits was the first variable included 

in the model, residualized air temperature was the second, 

and residualized peat deposits was the third. This model 

collectively explained 20 percent of the variance in N 

concentrations. 

For both of these constituents, removing the anthropogenic effects greatly reduced the predictability of the 

regression models. When the direct and indirect effects 

of the anthropogenic characteristics were included in 

the models, 56 to 72 percent of the variance could be 

explained with three variables; however, when all of the 

anthropogenic effects were removed, the models only 

explained about 20 percent of the variance.

To develop regression models to predict SCHL and 

SD, all of the water-quality characteristics and environmental characteristics (including the physical-habitat characteristics, such as shading, streambank erosion, and so on) were 

included. The percentage of total forest in the basin was the 

first variable incorporated into the model to predict SCHL, 

TKN was the second, and watershed area was the third. 

Collectively, this model explained 42 percent of the variance in SCHL concentrations. If the anthropogenic characteristics were simply omitted from the analysis, TKN was 

the first variable selected, watershed area was the second, 

and soil erodibility was the third. After the environmental 

characteristics were adjusted to remove the anthropogenic 

effects, TKN was the first variable incorporated in the 

model, watershed area was the second, and P was the third. 

This model explained 36 percent of the total variance. 

The percentage of row-crop agriculture in the basin 

was the first variable incorporated into the model to predict 

SDs, percentage of clay deposits was the second, and TKN 

was the third. Collectively, this model explained 43 percent 

of the variance in SDs. When the anthropogenic characteristics were omitted, total P was the first variable incorporated into the model, the percentage of clay deposits was 

the second, and DP was the third. After the environmental 

characteristics were adjusted to remove the anthropogenic 

effects, total P was the first variable included in the model, 

total N was the second, and DP was the third. This model 

explained 42 percent of the total variance. 

Removing the anthropogenic effects on the environmental characteristics had little effect on the predictability 

of the SCHL and SD models when nutrients were included 

in the models (second and third models). The anthropogenic characteristics were strongly correlated with nutrient 

concentrations, and therefore, similar predictability was 

obtained by including either the anthropogenic characteristics or the nutrient concentrations. The SD models 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 29
Table 6. Results of forward stepwise-regression analyses used to explain the variance in raw and residualized water-quality 

concentrations in the studied wadeable streams in Wisconsin. 

[all regressions were on log-transformed concentrations; r, Pearson correlation coefficient; R2, coefficient of determination for the one, two, and three 

variable models; Res, residualized]

Dependent variable First variable Second variable Third variable

Total phosphorus (P)

All environmental characteristics

P Total agriculture Point-source loading Loam deposits

r 0.66 0.34 0.24

Accumulative R2 .44 .51 .56

No anthropogenic characteristics

P Erodibility Runoff Loam deposits

r .54 -.54 .24

Accumulative R2 .29 .38 .44

Residualized characteristics

PRes LoamRes deposits Sand-and-gravelRes deposits NonglacialRes deposits

r .30 -.29 -.16

Accumulative R2 .09 .15 .19

Total nitrogen (N)

All environmental characteristics

N Total forest Precipitation Agriculture (row)

r -.82 .29 .77

Accumulative R2 .67 .69 .72

No anthropogenic characteristics

N Air temperature Soil slope Clay content of soil

r .75 -.19 .51

Accumulative R2 .56 .59 .61

Residualized characteristics

NRes ClayRes deposits Air temperatureRes PeatRes deposits

r -.35 .25 .16

Accumulative R2 .12 .17 .20

Suspended chlorophyll a (SCHL)

All environmental characteristics

SCHL Total forest Kjeldahl nitrogen Watershed area

r -.47 .46 .28

Accumulative R2 .22 .33 .42

No anthropogenic characteristics

SCHL Kjeldahl nitrogen Watershed area Erodibility

r .46 .28 .33

Accumulative R2 .21 .30 .41

Residualized characteristics

SCHLRes Kjeldahl nitrogen Watershed areaRes Total phosphorus

r .46 .28 .44

Accumulative R2 .21 .30 .36

Secchi tube depth (SD)

All environmental characteristics

SD Agriculture (row) Clay deposits Kjeldahl nitrogen

r -.55 -.32 -.37

Accumulative R2 .30 .37 .43

No anthropogenic characteristics

SD Total phosphorus Clay deposits Dissolved phosphorus

r -.53 -.32 -.44

Accumulative R2 .28 .36 .44

Residualized characteristics

SDRes Total phosphorus Total nitrogen Dissolved phosphorus

r -.53 -.53 -.44

Accumulative R2 .28 .36 .42

30 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
that included both P concentration and percentage of clay 

deposits were significantly better than models that only 

included P concentrations.

Redundancy Analysis

Each of the four primary water-quality characteristics 

(P, N, SCHL, and SD) has been shown to be influenced by 

the anthropogenic characteristics and other characteristics 

in the watershed upstream from the assessment site. The 

relative importance of these factors differs for each characteristic. The relative impor tance of each of the general 

types of environmental characteristics thought to influence the distribution of overall water quality, as defined by 

these four water-quality characteristics, was determined by 

partial RDA. 

In the partial RDA, the environmental characteristics 

were divided into three main categories: anthropogenic/

land-use characteristics, soil and surficial-deposit characteristics, and basin characteristics (table 2). A two-step 

process was used to select four characteristics to describe 

each category. The characteristics initially chosen were 

those significantly correlated with the individual waterquality characteristics. The final characteristics within a 

specific category were chosen to have minimal correlations 

among themselves. For example, the percentage of agriculture and the percentage of forest, although both strongly 

correlated with water quality, were not both chosen for 

the anthropogenic/land-use category because they were 

strongly correlated to one another. The anthropogenic/

land-use category was described by the percentages of 

total agriculture, urban, and open wetland, and the log PtS 

in the basin. Soils/surficial deposits were described by the 

clay content and organic-matter content of the soils, permeability, and erodibility. The basin characteristics were 

described by log (watershed area), precipitation, runoff, 

and basin slope. The anthropogenic/land-use characteristics category reflects the extent of human intervention—

characteristics that may be altered. The soil and surficialdeposit characteristics and basin characteristics catego ries 

reflect the geological and topographical effects—characteristics that cannot be altered.

The total variance in the four water-quality characteristics was separated into five categories: 1) variance 

explained by the anthropogenic/land-use characteristics 

alone, 2) variance explained by soil and surficial-deposit 

characteristics alone, 3) variance explained by the basin 

char acteristics alone, 4) variance explained by the interactions of anthropogenic/land-use, soil and surficial-deposit, 

and basin character istics (joint variation that could not 

be assigned to a single category), and 5) variance not 

explained by these characteristics. Results from the partial 

RDA indicated that these 12 characteristics collectively 

explained 43 percent of the variance in water quality (P, N, 

SCHL, and SD; p < 0.001). Independently, the anthropogenic/land-use characteristics explained 12 percent of the 

explained variance (5 percent of the total variance; 

p < 0.001; fig. 8), the soil and surficial-deposit characteristics explained 17 percent of the explained variance 

(7 percent of the total variance; p < 0.001), and the basin 

characteristics explained 4 percent of the explained variance (2 percent of the total variance; p < 0.15). The shared 

contribution or interactions of all three general categories 

of environmental characteristics explained about 67 of 

the explained variance or 30 percent of the total variance. 

Therefore, much of the variance in water quality could 

not be explained by a single category of environmental 

characteristics. 

RDA was also used to determine which environmental characteristics explained the most variance in overall 

water quality (P, N, SCHL, and SD). In RDA, as in principal-component analysis, the explained variance is separated into a series of ordination (canonical) axes. Almost 

all of the variance in this analysis was explained on the 

first canonical axis. Therefore, examination of the scores 

on the first axis (table 7) enables the determination of the 

importance of individual environmental characteristics and 

water-quality characteristics that have the most explained 

variance. Total N and SD had the highest scores (absolute 

values) on the first canonical axis, which indicates that 

more of their variance was explained by the environmental 

characteristics than were the variances in P and SCHL. 

The most important characteristics explaining the variance 

in these four water-quality characteristics in descending 

order of axis score were the percentage of agriculture in 

the basin, the clay content of the soil, soil erodibility, runoff, and permeability. The relations between the environmental characteristics and water-quality characteristics can 

be determined by comparing their respective axis scores. 

Areas with high percentages of agriculture, high clay-content soils, highly erodible soils, low runoff, and low soil 

permeability had the highest nutrient and SCHL concentrations and worst water clarity. These results agree with the 

findings of the correlation and regression analyses.

A multiple-regression approach (similar to partial 

RDA) was performed to determine how the total variance 

in SDs and SCHL, independently, could be separated into 

four categories: 1) variance explained by the 5 nutrients 

alone (P, DP, N, NO3

-N, and TKN), 2) variance explained 

by environmental characteristics alone (the same 12 

environmental characteristics used in the partial RDA for 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 31
water quality), 3) variance explained by the interactions 

between nutrients and environmental characteristics, and 

4) variance not explained by these characteristics. In this 

approach, three regressions were performed for SD and 

for SCHL; multiple regressions with all 17 variables, with 

only the 5 nutrients, and with only the 12 environmental 

characteristics. The first regression with all 17 variables 

was used to determine the total variance explained by all 

of the variables. The other two regressions were used to 

partition the variance between the three categories. The 

amount of variance explained by the interaction of the two 

categories was determined by equation 10:

 (10)

where

 EV is the explained variance by the specified group of 

variables.

The variance explained by each subset of variables alone 

was then determined by subtracting the variance explained 

by the interactions between the variables from the total 

variance explained by a subset of variables. For example, 

the variance explained by the nutrients alone is equal to 

the coefficient of determination for the nutrient regression 

minus the variance explained by the interactions. Results 

from this analysis indicated that these characteristics collectively explained about 55 percent of the variance in both 

SDs and SCHL concentrations. Nutrients alone explained 

22–23 percent of the explained variance in each of these 

characteristics (fig. 9). The environmental characteristics 

alone explained more of the variance in SCHL concentrations than in the SDs, whereas the interactions between 

the nutrients and environmental characteristics explained 

more of the variance in SDs than in SCHL concentrations. 

Again, much of the total variability in these two parameters could not be explained by the nutrients alone. 

Environmental Characteristics Most Strongly 

Related to Water Quality 

Correlations, stepwise regressions, and regressiontree analyses all indicated that the anthropogenic/land-use 

characteristics (primarily the amount of forest and agriculture in the basin) were the characteristics most strongly 

related to water quality. Simply omitting the anthropogenic 

characteristics and reanalyzing the data, however, may not 

provide a true indication of what factors affect water quality because some of the remaining factors may be correlated with the anthropogenic characteristics of the basins. 

For example, air temperature and clay content of the soil 

were both strongly correlated with many water-quality 

characteristics and with the percentage of agriculture in 

the basin (table 4). Therefore, it is difficult to determine 

whether it was these factors or the indirect effects of 

agriculture that affected water quality. The clay content 

of the soil has been demonstrated to have a strong effect 

on the water quality of Midwestern streams (Robertson, 

1997; Robertson and others, 2006); however, the effects of 

air temperature seem questionable and may be indirectly 

related to the anthropogenic characteristics. 

Various approaches were used to determine which 

other environmental characteristics were most strongly 

related to water quality. The results of partial RDA indicated 

that soil characteristics were important; however, much 

of the variance explained by soil characteristics was also 

explained by the anthropogenic/land-use characteristics. 

EVInteractions = , (EVNutrients + EVEnvironmental − EVAll Variables )

32 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Table 7. Results from redundancy analysis between waterquality and environmental (anthropogenic/land-use, basin, 

and soil and surficial-deposit) characteristics for the studied 

wadeable streams in Wisconsin.

[log, logarithm to base 10 transformation]

First canonical

axis score

Water-quality characteristics

Total phosphorus – log 0.54

Total nitrogen – log .67

Suspended chlorophyll a – log .48

Secchi tube depth -.65

Anthropogenic/land-use characteristics

Total agriculture .81

Urban .25

Open wetland .19

Point-source loading of phosphorus – log .31

Basin characteristics

Watershed area – log .00

Precipitation .23

Runoff -.61

Basin slope .11

Soil and surficial-deposit characteristics

Clay content of the soil .78

Erodibility .63

Organic-matter content -.24

Permeability -.58
Results of RDA indicated that the most important soil 

characteristics were the clay content of the soils, soil erodibility, and soil permeability. The results also indicated that 

the amount of runoff was also strongly related to water 

quality.

The results of the residualization analyses indicated 

that the natural (nonanthropogenic) environmental characteristics most strongly related to the distribution of P were 

soil permeability, the soil slope, and the percentage of 

sand-and-gravel deposits. The natural environmental characteristics most strongly related to the distribution of N 

were the percentage of clay deposits and other basin characteristics. A few of the natural characteristics, however, 

such as clay content of the soil and soil erodibility, were 

so strongly correlated with the percentage of agriculture 

in the basin that their relation to water quality may have 

been removed by the residualization approach. Stepwise 

regressions with residualized environmental characteristics 

only explained about 20 percent of the variance in P and N 

concentrations. 

In addition to anthropogenic/land-use characteristics, 

residualization analyses indicated that the distribution of 

SCHL concentrations and SDs were related to concentrations of P and various forms of nitrogen. Other important 

A. Percentages of explained variance in Secchi

 tube depth

22%

22% 56%

Nutrients

Environmental characteristics

Interactions among

categories

B. Percentage of explained variance in

 suspended chlorophyll a

23%

34%

43%

General categories

Figure 9. Percentages of explained variance in A, Secchi tube depths and B, suspended chlorophyll a concentrations described 

by nutrients, environmental characteristics (anthropogenic/land-use, soil, and surficial-deposit characteristics), and interactions 

among categories (variance that can not be explained by a single category) for the studied wadeable streams in Wisconsin. 

[%, percentage of explained variance]

12% 4%

17%

67%

Anthropogenic/land-use characteristics

General categories

Basin characteristics

Soil and surficial-deposit characteristics

Interactions among categories

Figure 8. Percentages of explained variance in water quality (total phosphorus, total nitrogen, and suspended chlorophyll a

concentrations and Secchi tube depth) described by anthropogenic/land-use, basin, soil and surficial-deposit characteristics, 

and interactions among categories (variance that can not be explained by a single category) for the studied wadeable streams in

Wisconsin. [%, percentage of explained variance]

Water Quality and Its Relations with Environmental Characteristics in the Watershed 33
natural characteristics related to SCHL concentrations 

were the slope of the basin and the soils, the organic-matter content of the soil, and some surficial-deposit characteristics. Other important natural characteristics related to 

SDs were the clay content of the soil and surficial deposits. 

Regionalization Schemes for Reference 

Water Quality and the Response in Water 

Quality to Changes in Land Use

The two primary regionalization schemes considered 

in choosing the sites for this study and for developing 

nutrient criteria for Wisconsin were the level III ecoregions of Omernik and others (2000) and the environmental 

phosphorus zones of Robertson and others (2006) (fig. 2). 

In addition, a third regionalization scheme was considered after the sites were chosen and sampled. In this third 

scheme, the EPZs were refined based on the water-quality 

and environmental characteristics of only the 240 sites in 

this study rather than from information from sites throughout the entire upper Midwest. To refine the EPZs in figure 

2B, the SPARTA approach (Robertson and others, 2006) 

was used with land-use-adjusted (residualized) waterquality and environmental characteristics computed for 

each site to remove the direct and indirect effects of land 

use (and PtS). P concentrations and many of the natural 

environmental characteristics related to P (such as the clay 

content of the soil and soil erodibility) were so strongly 

correlated with land use (and PtS) that the residualization 

process almost completely removed their relations with 

residualized P concentrations. These correlations resulted 

in a regionalization scheme that explained very little variance in P concentrations and which did not demonstrate 

clear regional patterns. Therefore, the revised EPZ regionalization scheme based on data from only the 240 sites in 

this study was discarded. 

The primary purpose of most regionalization schemes 

is to minimize the variability in water quality within 

regions and maximize the variability among regions. This 

purpose was the reasoning behind the use of Omernik’s 

ecoregions as the building block for USEPA’s nutrient ecoregions. The distribution of agriculture differs 

among the four level III ecoregions in Wisconsin (fig. 

10A). Almost 90 percent of the sites in the NLF had less 

than 8 percent agriculture in their basins; whereas, over 

75 percent of the sites in the SWTP had over 50 percent 

agriculture in their basins. The use of land-use information 

to delineate specific regions may minimize the variability 

in water quality within the ecoregions across the upper 

Midwest and in Wisconsin because land use is the most 

important factor influencing the geographic distribution of 

most water-quality characteristics. The USEPA, however, 

has stated that the environmental characteristics used to 

delineate regions of similar reference or potential water 

quality should be restricted, as much as possible, to those 

that are intrinsic, or natural, and not the result of human 

activities (U.S. Environmental Protection Agency, 2000a). 

Therefore, the most appropriate stratification scheme for 

developing nutrient criteria for Wisconsin should be one 

that delineates areas with different reference or potential nutrient concentrations (not necessarily actual water 

quality), different responses in nutrient concentrations 

to changes in land use, and different biotic responses to 

changes in nutrients.

Reference Water-Quality Conditions

Various approaches have been used to define reference water quality for specific areas. Reference water 

quality is also referred to as background or potential 

water quality in other publications. In defining reference 

conditions for national nutrient criteria, the USEPA has 

suggested that a value based on the frequency distribution 

of the data available for a specific area could be used to 

define a reference condition. The USEPA has suggested 

that the value indicative of reference conditions be defined 

as the lower 25th percentile of all the data for that area 

or the upper (or worst) 75th percentile of the data for a 

subset of streams thought to be minimally impacted (U.S. 

Environmental Protection Agency, 2000a). Because it 

is often difficult to determine which sites are minimally 

impacted, the lower 25th percentile is the more common 

approach and the one that has been used by the USEPA to 

define their proposed water-quality criteria (table 1; U.S. 

Environmental Protection Agency, 2004).

One of the problems with the percentile approach 

(25th percentile) is that differences in land use within 

the ecoregions and zones can strongly affect the results 

for characteristics correlated with land use, such as the 

water-quality characteristics examined in this study. The 

reference P and N concentrations based on the percentile 

approach were directly related to the percentage of the 

sites within each ecoregion or zone dominated by agriculture. In the ecoregions examined in this study, the percentages of sites dominated by agriculture decrease from 

the SWTP to DFA to NCHF to NLF (fig. 10A). These 

differences in land use result in a gradient of conditions 

affecting water quality, and result in P, N, and SCHL concentrations and SDs at the 25th percentile that follow the 

same gradient (25th percentiles in table 8). For the EPZs, 

34 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
0

10

20

30

40

50

0.0 0.1 0.2 0.3

TOTAL PHOSPHORUS CONCENTRATIONS, IN MILLIGRAMS PER LITER

PERCENTAGE OF SITES IN ECOREGION

0

10

20

30

40

50

0.0 0.1 0.2 0.3

TOTAL PHOSPHORUS CONCENTRATIONS, IN MILLIGRAMS PER LITER

PERCENTAGE OF SITES IN EPZ

0

10

20

30

40

50

01234567 8

TOTAL NITROGEN CONCENTRATIONS, IN MILLIGRAMS PER LITER

PERCENTAGE OF SITES IN ECOREGION

0

10

20

30

40

50

01234567 8

TOTAL NITROGEN CONCENTRATIONS, IN MILLIGRAMS PER LITER

PERCENTAGE OF SITES IN EPZ

0

10

20

30

40

50

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

PERCENTAGE OF SITES IN ECOREGION

0

10

20

30

40

50

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

PERCENTAGE OF SITES IN EPZ

DFA

NCHF

NLF

SWTP

DFA

NCHF

NLF

SWTP

DFA

NCHF

NLF

SWTP

EPZ 1

EPZ 2

EPZ 3

EPZ 4

EPZ 1

EPZ 2

EPZ 3

EPZ 4

EPZ 1

EPZ 2

EPZ 3

EPZ 4

A.

B.

C.

Figure 10. Percentiles of A, total agriculture in the watersheds, B, total phosphorus, and C, total nitrogen in streams in the level 

III ecoregions and environmental phosphorus zones (EPZs) for the studied wadeable streams in Wisconsin. [DFA, Driftless Area; 

NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

Water Quality and Its Relations with Environmental Characteristics in the Watershed 35
Table 8. Reference conditions for total phosphorus, total nitrogen, and suspended chlorophyll a concentrations, and Secchi tube depths in the environmental phosphorus zones 

and level III ecoregions for wadeable streams in Wisconsin. Median reference values, standard errors, and upper 95-percent confidence limits were estimated with the multiple linear-regression approach.[USEPA, U.S. Environmental Protection Agency; EPZ, environmental phosphorus zone; DFA, driftless area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; SWTP, Southeastern Wisconsin Till Plains; --, no data; mg/L, milligram per liter; μg/L, microgram per liter; cm, centimeter; >, greater than; --, not available] 

Zone/

ecoregion

Number 

of sites

Multiple linear-regression approach USEPA 

criteria

Percentiles

Median 

reference

Standard 

error

Upper 95-percent 

confidence limit 0 10 25 50 75 90 100

Total phosphorus (mg/L)

EPZ 1 69 0.032 0.003 0.039 -- 0.012 0.019 0.027 0.041 0.092 0.139 0.527EPZ 2 58 .042 .006 .054 -- .016 .022 .044 .092 .159 .237 .304EPZ 3 25 .029 .006 .043 -- .018 .036 .053 .150 .203 .297 .741EPZ 4 84 .035 .009 .055 -- .027 .043 .061 .095 .128 .210 1.641DFA 58 .040 .008 .057 .070 .027 .040 .053 .087 .121 .183 .611NCHF 48 .041 .009 .060 .029 .019 .027 .054 .106 .176 .258 .527NLF 62 .032 .002 .036 .010 .012 .017 .024 .036 .063 .101 .160SWTP 72 .025 .008 .044 .080 .023 .053 .072 .114 .199 .297 1.641

Total nitrogen (mg/L)

EPZ 1 69 .557 .057 .676 -- .191 .353 .486 .808 1.690 4.005 8.240EPZ 2 58 .632 .066 .771 -- .298 .492 .793 1.303 2.095 4.710 21.260EPZ 3 25 .367 .103 .601 -- .131 .244 1.318 2.481 3.340 5.095 10.465EPZ 4 84 .690 .161 1.050 -- .780 1.240 1.780 2.920 6.420 8.720 13.205DFA 58 .643 .118 .901 1.880 .882 1.223 1.489 2.563 6.300 8.145 11.385NCHF 48 1.132 .229 1.637 .460 .391 .698 1.188 1.646 2.843 4.870 8.240NLF 62 .509 .038 .587 .200 .131 .298 .403 .548 .793 1.158 1.435SWTP 72 .811 .258 1.409 1.590 .777 1.361 2.020 3.204 5.110 8.720 21.260

36 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Water Quality and Its Relations with Environmental Characteristics in the Watershed 37

Table 8. Reference conditions for total phosphorus, total nitrogen, and suspended chlorophyll a concentrations, and Secchi tube depths in the environmental phosphorus zones and level III ecoregions for wadeable streams in Wisconsin—Continued. Median reference values, standard errors, and upper 95-percent confidence limits were estimated with the multiple linear-regression approach.[USEPA, U.S. Environmental Protection Agency; EPZ, environmental phosphorus zone; DFA, driftless area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; SWTP, Southeastern Wisconsin Till Plains; --, no data; mg/L, milligram per liter; μg/L, microgram per liter; cm, centimeter; >, greater than; --, not available]

Zone/

ecoregion

Number 

of sites

Multiple linear-regression approach USEPA 

criteria

Percentiles

Median 

reference

Standard 

error

Upper 95-percent 

confidence limit 0 10 25 50 75 90 100

Suspended chlorophyll a (μg/L, trichromatic method)

EPZ 1 69 1.56 0.17 1.93 -- 0.40 0.65 1.37 1.95 2.63 3.97 14.64EPZ 2 58 1.71 .24 2.23 -- .45 1.03 1.56 2.34 3.86 5.60 38.01EPZ 3 25 1.03 .24 1.55 -- .77 1.14 1.62 2.48 3.80 7.11 36.63EPZ 4 84 1.17 .25 1.72 -- .94 1.35 1.86 2.44 3.48 5.94 23.51DFA 58 1.48 .25 2.02 -- .94 1.35 1.75 2.16 2.90 4.12 14.64NCHF 48 1.73 .41 2.65 -- .40 .74 1.49 2.43 3.84 5.78 7.46NLF 62 1.49 .12 1.74 -- .41 .77 1.08 1.71 2.34 3.06 4.82SWTP 72 1.44 .54 2.71 -- 1.19 1.62 2.02 3.07 5.22 10.10 38.01

Secchi tube depth (cm)

EPZ 1 69 115.0 2.5 >120.0 -- 35.5 98.0 >120.0 >120.0 >120.0 >120.0 >120.0EPZ 2 58 117.7 4.9 >120.0 -- 27.0 47.5 88.5 117.5 >120.0 >120.0 >120.0EPZ 3 25 109.5 10.6 >120.0 -- 23.5 42.5 51.5 76.0 102.5 >120.0 >120.0EPZ 4 84 >120.0 10.2 >120.0 -- 25.5 41.5 65.3 95.5 >120.0 >120.0 >120.0DFA 58 118.6 9.2 >120.0 -- 35.5 50.0 67.5 98.0 >120.0 >120.0 >120.0NCHF 48 104.4 6.2 116.9 -- 35.5 81.0 102.3 >120.0 >120.0 >120.0 >120.0NLF 62 116.5 1.7 119.8 -- 66.0 102.0 >120.0 >120.0 >120.0 >120.0 >120.0SWTP 72 >120.0 13.4 >120.0 -- 23.5 33.0 47.8 84.0 108.3 >120.0 >120.0
the percentages of agriculture in the basins decreased 

from EPZ 3 to EPZ 4 to EPZ 2 to EPZ 1, and results for 

the nutrient concentrations and SDs at the 25th percentile 

followed the same gradient except for EPZ 3 and EPZ 4, 

which were sometimes reversed (table 8). Therefore, the 

values of the water-quality characteristics at the 25th percentile do not appear to represent the true, or even relative, 

reference conditions for these different ecoregions and 

zones. The differences in the values at the 25th percentile 

represent the differences in the types of land uses among 

the different ecoregions and zones. 

Another approach to estimate reference concentrations is a multiple linear-regression model that relates 

water quality to anthropogenic characteristics (Dodds and 

Oakes, 2004). After calibrating the model with data from 

a specific area, an estimate of reference conditions in the 

absence of anthropogenic activities can be obtained by setting the variables describing anthropogenic characteristics 

to 0 (in this study, setting percentage of agricultural area 

to 0, percentage of urban area to 0, and PtS to 0). These 

relations can also be used to place confidence intervals on 

the reference concentrations. Reference conditions were 

computed for each level III ecoregion and EPZ (fig. 2) 

based on all of the data available for each area with the 

general multiple linear-regression model:

 Log PPredicted = a + bAg% + cUrb% + d Log(PtS), (11)

where

 a, b, c and d are empirical coefficients determined for 

each area.

The general form of this model is similar to that used 

to estimate residualized concentrations in equations 3, 5, 

7, and 9 (pages 24 and 25). Because this type of model 

estimates the logarithm of the reference concentration, the 

median reference concentration for each area was estimated as 10a

. For each level III ecoregion and EPZ, the 

median reference condition, the standard error of the reference condition, and the upper bound of the 95-percent confidence interval of the reference condition were estimated 

(table 8). A bias correction is typically applied to results 

for mean values obtained by logarithmic regression; however, the bias correction was not used here because of the 

choice of median rather than mean reference conditions.

Total Phosphorus 

Reference concentrations for P ranged from 0.029 

mg/L in EPZ 3 to 0.042 mg/L in EPZ 2, with the upper 

95-percent confidence intervals ranging from 0.039 mg/L 

in EPZ 1 to 0.055 mg/L in EPZ 4 (table 8). No statistical 

differences are present among the reference concentrations for these zones. The regression approach was also 

used to estimate reference concentrations for each level 

III ecoregion. Reference concentrations ranged from 

0.025 mg/L in the SWTP to 0.041 mg/L in the NCHF. The 

upper 95-percent confidence intervals ranged from 0.036 

mg/L in the NLF to 0.060 mg/L in the NCHF. Again, no 

statistical differences are present among these concentrations. The standard errors for the reference concentrations 

of the EPZs were similar in magnitude to those of the 

ecoregions (from 0.002 to 0.009 mg/L); therefore, neither 

regionalization scheme was better in estimating reference 

P concentrations. Both regionalization schemes indicate 

that one reference P concentration would be appropriate 

for wadeable Wisconsin streams: 0.03–0.04 mg/L with an 

upper 95-percent confidence limit of 0.04–0.06 mg/L. 

Total Nitrogen 

Reference concentrations for N ranged from 0.367 

mg/L in EPZ 3 to 0.690 mg/L in EPZ 4, with the upper 

95-percent confidence intervals ranging from 0.601 mg/L 

in EPZ 3 to 1.050 mg/L in EPZ 4 (table 8). Reference 

concentrations for EPZ 3 were lower than those for the 

other EPZs; however, the differences were not significant 

at p < 0.05. Reference concentrations ranged from 0.509 

mg/L in the NLF to 1.132 mg/L in the NCHF. The upper 

95-percent confidence intervals ranged from 0.587 mg/L in 

the NLF to 1.637 mg/L in the NCHF. Reference concentrations for the NCHF were slightly higher than those for the 

other ecoregions; however, no statistical differences were 

present between these concentrations. The standard errors 

of the reference concentrations of the EPZs ranged from 

0.066 to 0.161 mg/L, compared to 0.038 to 0.258 mg/L 

for the level III ecoregions; the 95-percent confidence 

limits for the EPZs were generally smaller than those 

of the ecoregions. Therefore, the EPZs provided more 

precise estimates of reference N concentrations, although 

the differences were not significant at p < 0.05. On the 

basis of the EPZ regionalization scheme, two reference N 

concentrations may be appropriate for wadeable Wisconsin 

streams: 0.6–0.7 mg/L in all streams except those in EPZ 

3, where 0.4 mg/L may be more appropriate.

38 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Suspended Chlorophyll a

Reference concentrations for SCHL ranged from 

1.03 μg/L in EPZ 3 to 1.71 μg/L in EPZ 2, with the upper 

95-percent confidence intervals ranging from 1.55 μg/L in 

EPZ 3 to 2.28 μg/L in EPZ 2 (table 8). Reference concentrations for EPZ 3 were lower than those for the other 

EPZs; however, the differences were not significant at 

p < 0.05. Reference concentrations ranged from 1.44 to 

1.73 μg/L in the four level III ecoregions, with the upper 

95-percent confidence intervals ranging from 1.74 μg/L 

in the NLF to 2.71 μg/L in the SWTP. Again, the differences were not significant at p < 0.05. The standard errors 

for the reference concentrations of the EPZs ranged from 

about 0.17 to 0.25 μg/L compared to 0.12 to 0.54 μg/L for 

the ecoregions; the 95-percent confidence limits for the 

EPZs were generally smaller than those of the ecoregions. 

Therefore, the EPZs provided more precise estimates of 

reference SCHL concentrations, although the differences 

were not significant at p < 0.05. On the basis of the EPZ 

regionalization scheme, two reference SCHL concentrations may be appropriate for wadeable Wisconsin streams: 

1.2–1.7 μg/L in all streams except those in EPZ 3, where 

1.0 μg/L may be more appropriate.

Reference SCHL concentrations and the relative 

importance of P and N in controlling or limiting SCHL 

at low nutrient concentrations was also estimated by 

examining the SCHL concentrations in sites with either or 

both reference P and reference N concentrations. For this 

analysis, the 240 sites were divided into five categories: 

reference sites (Reference, fig. 11)—36 sites with both P 

concentrations at or below the 0.04-mg/L reference concentration and N concentrations at or below the 0.70-mg/L 

reference concentration; reference P sites (Ref P)—22 sites 

with P concentrations at or below the reference concentration, but with N concentrations above the reference 

concentration; reference N sites (Ref N)—10 sites with N 

concentrations at or below the reference concentration, but 

with P concentrations above the reference concentration; 

high nutrient-concentration sites (High)—135 sites with 

both P and N concentrations above their respective upper 

95-percent confidence limits for reference concentrations 

Reference High Ref N Ref P

-0.5

0.0

0.5

1.0

1.5

2.0

LOG (SUSPENDED CHLOROPHYLL 

A,

IN MICROGRAMS PER LITER)

Reference High Ref N Ref P 0

20

40

60

80

100

120

SECCHI TUBE DEPTH, 

IN CENTIMETERS

EXPLANATION

Outlier

Interquartile

range (IR)

75th percentile + 1.5 * IR

25th percentile – 1.5 * IR

75th percentile 

25th percentile 

Median

A.

B.

Figure 11. A, suspended chlorophyll a (SCHL) concentrations and B, Secchi tube depths (SDs) in Reference sites, High 

(nonreference) sites, and sites with only reference total nitrogen (Ref N sites) or reference total phosphorus (Ref P sites) 

concentrations in the studied wadeable streams in Wisconsin.

Water Quality and Its Relations with Environmental Characteristics in the Watershed 39
(P concentrations above 0.06 mg/L and N concentrations 

above 1.0 mg/L); and nonclassified sites—37 sites with 

P and N concentrations above their respective reference 

concentrations but below their upper 95-percent confidence limits (these sites were not included in this analysis 

and not included in figure 11). Comparison of the SCHL 

concentrations for the Reference sites with those of the Ref 

P and Ref N sites is similar to the comparison of SCHL 

concentrations for nutrient-addition experiments. SCHL 

concentrations for Ref P sites are similar to SCHL concentrations for experiments with N additions, and the SCHL 

concentrations for the Ref N sites are similar to those for 

experiments with P additions. 

The approach described above was used to estimate 

the reference SCHL concentration for the entire State 

because nutrient concentrations at or below reference concentrations were primarily measured only in the northern 

part of the State. The median SCHL concentration of the 

Reference sites was 1.46 μg/L (log(1.46) = 0.16), with the 

upper 75th percentile being 2.22 μg/L (log(2.22) = 0.35), 

which was significantly less than the median concentration of 2.75 μg/L (log(2.75) = 0.44) measured in the High 

sites (fig. 11A). It has been suggested by the USEPA that 

the upper 75th percentile of a subset of streams thought 

to be minimally impacted (Reference sites) may represent 

the reference condition; therefore, an alternative reference 

SCHL concentration for the entire State would be 2.22 

μg/L. The reference values estimated with both approaches 

are less than those defined by the USEPA for nutrient 

ecoregions 7 and 8 when the trichromatic method of analysis is used (5.8 and 4.3 μg/L, respectively; table 1). 

Comparing the median concentration for the Reference sites with the median concentrations for the Ref N 

and Ref P sites may provide an indication of whether P 

or N is more important in limiting the concentrations of 

SCHL in streams with nutrient concentrations near reference conditions (fig. 11A). The median SCHL concentrations for Ref P and Ref N sites were both higher than that 

for the Reference sites, although the median concentrations 

for these categories were not statistically different from 

one another at p < 0.05. The Ref N sites had a median 

SCHL concentration most different from that of the 

Reference sites; therefore, it appears that it may be more 

important to have low P concentrations than low N concentrations to limit SCHL concentrations (in other words, 

potential P limitation for sites near reference conditions). 

Secchi Tube Depth 

Reference SDs ranged from about 110 cm in EPZ 3 

to greater than 120 cm in EPZ 4, with all upper 95-percent confidence intervals greater than 120 cm (table 8). 

These differences were not statistically different from one 

another at p < 0.05. Reference SDs ranged from 104.4 cm 

in the NCHF to greater than 120 cm in the SWTP. The 

upper 95-percent confidence intervals ranged from 116.9 

cm in the NCHF to greater than 120 cm in the DFA and 

the SWTP. These differences were not statistically different from one another at p < 0.05. The standard errors of 

the EPZs ranged from 2.5 to 10.6 cm, compared to 1.7 to 

13.4 cm for the ecoregions. Therefore, the EPZs provided 

slightly more precise estimates of reference clarity than 

the level III ecoregions, although the differences were not 

statistically different from one another at p < 0.05. On the 

basis of the EPZ regionalization scheme, two reference 

SDs may be appropriate for wadeable Wisconsin streams: 

greater than 115 cm for all streams except those in EPZ 3, 

where greater than 110 cm may be more appropriate.

A reference SD was also determined by examining 

the sites at which both P and N concentrations were at 

or below their respective reference concentrations. The 

median SD measured at the Reference sites was greater 

than 120 cm, which was significantly greater than the 

median SD measured in the High sites (90 cm; fig. 11B). 

The lower 25th percentile of SDs at the Reference sites 

(equivalent to the worst 75th percentile of the minimally 

impacted sites) was greater than 120 cm; therefore, an 

alternative reference SD for the entire State would be 

greater than 120 cm. The median SDs for Ref P and Ref N 

sites were similar to that for the Reference sites (fig. 11B); 

therefore, a 120-cm Secchi tube was not long enough to 

determine whether small increases in P or N concentrations were more important in reducing water clarity. 

Responses of Nutrient Concentrations to 

Changes in Land Use

The responses of specific nutrients to changes in land 

use or other anthropogenic characteristics, such as PtS, can 

be estimated for each EPZ and ecoregion by the ways in 

which concentrations in each area change as a function of 

a specific anthropogenic characteristic. Overall, concentrations of P and N increase as the percentage of agricultural land increases (figs. 12A, B and 13A, B); however, 

variation in these responses may be associated with other 

40 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
A. Total phosphorus by environmental phosphorus zone

-0.5-1.0-1.5-2.0

0.50.0

0 20 40 60 80 100

LOG (TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER)

LOG (TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER)

B. Total phosphorus by ecoregion

-0.5-1.0-1.5-2.0

0.50.0

0 20 40 60 80 100

D. Response as a function of the percentage of total agriculture

0.40.30.20.10.0

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

C. Response as a function of the percentage of total agriculture

0.40.30.20.10.0

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

PERCENTAGE OF AGRICULTURAL LAND USE PERCENTAGE OF AGRICULTURAL LAND USE

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTP

EPZ 1EPZ 2EPZ 3EPZ 4All Data

DFANCHFNLFSWTPAll Data

Figure 12. Total phosphorus concentrations as a function of the percentage of agricultural land use in 

A, environmental phosphorus zones (EPZs) and 

B, level III ecoregions, 

and response curves for phosphorus concentrations as a function of the percentage of agriculture in the watershed, in 

C, EPZs, and 

D, level III ecoregions for wadeable streams 

in Wisconsin. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

Water Quality and Its Relations with Environmental Characteristics in the Watershed 41
B. Total nitrogen by ecoregion

-0.5-1.0

1.51.00.50.0

PERCENTAGE OF AGRICULTURAL LAND USE

LOG (TOTAL NITROGEN, 

IN MILLIGRAMS PER LITER)

A. Total nitrogen by environmental phosphorus zone

-0.5-1.0-1.5-2.0

1.51.00.50.0

0 20 40 60 80 100 0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

LOG (TOTAL NITROGEN, 

IN MILLIGRAMS PER LITER)

D. Response as a function of total agriculture by ecoregion

86420

10

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

TOTAL NITROGEN, 

IN MILLIGRAMS PER LITER

C. Response as a function of total agriculture by environmental phosphorus zone

86420

10

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

TOTAL NITROGEN, 

IN MILLIGRAMS PER LITER

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTP

DFANCHFNLFSWTPAll Data

EPZ 1EPZ 2EPZ 3EPZ 4All Data

Figure 13. Total nitrogen concentrations as a function of the percentage of agricultural land use in 

A, environmental phosphorus zones (EPZs) and 

B, level III ecoregions, and 

response curves for nitrogen concentrations as a function of the percentage of agriculture in the watershed, in 

C, EPZs, and 

D, level III ecoregions for wadeable streams in 

Wisconsin. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

42 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
anthropogenic characteristics such as differences in PtS 

or the percentage of urban area in the watershed. The four 

sites in EPZ 5 are plotted in figures 12 and 13 (and in the 

figures for other water-quality characteristics and biotic 

indices); however, these sites were not used to obtain 

regression lines or used in the multiple-regression analyses 

for P or any of the other water-quality characteristics.

A better approach to estimate the response of specific water-quality characteristics to changes in specific 

anthropogenic characteristics is the use of multiple-regression equations, such as those used to estimate reference 

concentrations. The response of a specific water-quality 

characteristic (for example, P) can be estimated for each 

EPZ and level III ecoregion shown in figure 2 by first 

determining values for the coefficients a, b, c, and d, in 

equation 11 on page 38 on the basis of all of the available 

data for each zone or ecoregion. Concentrations can then 

be predicted as a function of specific anthropogenic characteristics by varying the characteristic of interest while 

holding the other characteristics constant; in this case, at 0 

percent or 0 PtS (figs. 12C, D and 13C, D). This approach 

removes the complicating effects of the other characteristics. Because this equation estimates the logarithm of the 

concentration, the final concentrations were computed as 

10 a

. A bias correction is typically applied to the results for 

mean values obtained by logarithmic regression; however, 

a bias correction was not used here because of the choice 

of median rather than mean concentrations.

Plots of the regression lines show that concentrations of P increase as the percentage of agricultural land 

increases in all of the EPZs and ecoregions (figs. 12A, 

B); however, a more detailed evaluation of the responses 

of P concentrations in the EPZs and ecoregions can be 

made with multiple-regression analysis. The response 

of P concentrations to changes in only the percentage 

of agricultural land was largest in EPZ 1, followed by 

EPZ3, EPZ 2, and EPZ 4 (fig. 12C). To determine if these 

responses were statistically significant from one another, 

the standard errors in the estimates of coefficient b were 

used to place 95-percent confidence limits on the estimated 

values (table 9). The responses in P concentrations in EPZ 

1 and EPZ 3 were larger than the responses in the other 

EPZs, although their 95-percent confidence intervals for 

coefficient b slightly overlapped those of the other EPZs. 

Because most of the sites in EPZ 1 were in areas with 

limited agriculture, this difference may not reflect changes 

that would occur at higher percentages of agriculture. 

Changes in P concentrations as a function of only the 

percentage of agricultural land were largest in the NLF 

ecoregion, followed by NCHF, SWTP, and DFA (fig. 12D). 

The response in concentrations in the NLF was significantly larger than in any other ecoregion; however, similar 

to EPZ 1, the ranges in the percentage of agriculture and 

measured P concentrations were limited, and, therefore, 

this difference may simply reflect the distribution of the 

original data. The standard errors in the estimates of coefficient b for the EPZs ranged from 0.12 to 0.15 compared 

to 0.13 to 0.40 for the ecoregions. Therefore, the EPZs 

provided better estimates of the response to changes in the 

amount of agriculture than the level III ecoregions. Based 

on the EPZ regionalization scheme, subdividing wadeable 

streams in Wisconsin into two categories seems appropriate: streams in areas with high clay-content soils (EPZ 3), 

which respond more dramatically to changes in the amount 

of agriculture, and streams in the rest of the State. 

Concentrations of N also increase as the percentage of agricultural land increases in all of the EPZs and 

ecoregions (fig. 13). The responses in concentrations in 

EPZ 1 and EPZ 4 were larger than the responses in the 

other EPZs, and the response in concentrations in EPZ 3 

was smaller than those in the other EPZs; however, these 

differences were not statistically significant at p < 0.05. 

The changes in N concentrations were largest in the DFA, 

followed by SWTP, NLF, and NCHF. The response in 

concentrations in the DFA was significantly larger than 

in the NCHF, but not significantly larger than in the other 

ecoregions at p < 0.05. The response in concentrations in 

EPZ 1 was larger than in any other EPZ and the response 

in NLF was smaller than in any other ecoregion; however, 

this difference may simply reflect the distribution of the 

original data. The standard errors in the estimates of coefficient b for the EPZs ranged from 0.10 to 0.16 compared 

to 0.12 to 0.40 for the ecoregions (table 9). Therefore, the 

EPZs provided better estimates of the response to changes 

in the percentage of agricultural land use than the level 

III ecoregions. Based on the EPZ regionalization scheme, 

subdividing wadeable streams in Wisconsin into two categories seems appropriate: streams in areas with clay soils 

(EPZ 3), which respond less dramatically to changes in the 

amount of agriculture, and streams in the rest of the State. 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 43
Table 9. Responses to changes in the percentage of agricultural land use in the watershed. Estimated values for coefficient 

b for total phosphorus, total nitrogen, and suspended chlorophyll a concentrations, and Secchi tube depths in environmental 

phosphorus zones and level III ecoregions for wadeable streams in Wisconsin.

[b, factor associated with the percentage of agriculture in the watershed (eq. 11 in the text on page 38); mg/L, milligram per liter; μg/L, microgram per 

liter; cm, centimeter, EPZ, environmental phosphorus zone; DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and 

Forests; SWTP, Southeastern Wisconsin Till Plains]

Zone/ecoregion Estimated value for b Standard error for b Upper 95-percent 

confidence value for b

Total phosphorus

EPZ 1 1.03 0.15 1.33

EPZ 2 0.70 .13 0.96

EPZ 3 .99 .12 1.23

EPZ 4 .63 .15 .93

DFA .48 .13 .74

NCHF .95 .19 1.33

NLF 2.28 .40 3.08

SWTP .95 .18 1.31

Total nitrogen

EPZ 1 1.33 .14 1.61

EPZ 2 1.03 .10 1.23

EPZ 3 1.19 .16 1.51

EPZ 4 1.09 .14 1.37

DFA 1.19 .12 1.43

NCHF .49 .18 .85

NLF .96 .40 1.76

SWTP .90 .17 1.24

Suspended chlorophyll a

EPZ 1 .22 .16 .55

EPZ 2 .36 .14 .63

EPZ 3 .60 .13 .87

EPZ 4 .54 .13 .80

DFA .35 .35 1.05

NCHF .16 .20 .55

NLF .93 .44 1.80

SWTP .47 .20 .86

Secchi tube depth

EPZ 1 -7.1 8.7 10.3

EPZ 2 -49.8 11.0 -27.8

EPZ 3 -53.0 15.4 -22.1

EPZ 4 -48.5 16.1 -16.2

DFA -42.1 15.2 -11.8

NCHF 8.8 13.7 36.2

NLF -33.8 21.5 9.3

SWTP -89.0 19.2 -50.5

44 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Responses of Chlorophyll a Concentrations 

and Secchi Tube Depth to Changes in Nutrient 

Concentrations and Land Use

Concentrations of SCHL increased as P and N concentrations increased; however, there was much variation 

in these relations (fig. 14). For any nutrient concentration, 

there was about an order of magnitude of variation in 

SCHL concentrations. Although nutrient concentrations 

were lower or higher in some areas (especially lower in 

EPZ 1 and the NLF ecoregion), there was a relatively similar response in SCHL concentrations to changes in nutrient 

concentrations in all EPZs and level III ecoregions. Five 

sites, however, had SCHL concentrations that were lower 

than might be expected for the measured P and N concentrations at the site. These sites were in EPZ 1 and the 

NCHF, and were generally small sites (5.8–55.6 km2) with 

extensive sedimentation and embedded rocky substrate 

(94–100 percent).

The best breakpoints or thresholds in the response 

of SCHL to changes in P and N concentrations were at 

0.070 mg/L (log(P) = -1.16) and 1.169 mg/L (log(N) = 

0.07), respectively. This P concentration is expected to 

occur at approximately 30- to 50-percent agriculture in all 

areas (fig. 12). This N concentration is expected to occur 

at approximately 30-percent agriculture in all areas except 

EPZ 3, where it occurs at about 50-percent agriculture (fig. 

13). 

Water clarity (SDs) decreased as P and N concentrations increased (fig. 15). At low nutrient concentrations, 

water clarity often exceeded the 120-cm length of the Secchi tube. Then, as nutrient concentrations increased, water 

clarity decreased; however, there was much variation in 

this relation. For most nutrient concentrations, other than 

very low concentrations, SDs ranged from 20 cm to greater 

than 120 cm. In general, the SD responses were similar in 

most EPZs and ecoregions. The best breakpoints or thresholds in the response of SDs to changes in P and N concentrations were at 0.106 mg/L (log(P) = -0.97) and 3.305 

mg/L (log(N) = 0.52), respectively. This P concentration 

is expected to occur at approximately 50- to 70-percent 

agriculture in all areas (fig. 12). This N concentration is 

expected to occur at approximately 55- to 70-percent agriculture in all areas except EPZ 3, where it occurs at about 

80-percent agriculture (fig. 13). 

The multiple-regression approach was again used 

to estimate changes in SCHL concentrations and SDs in 

response to changes in the percentage of agricultural land 

in the watershed. Concentrations of SCHL increased as the 

percentage of agricultural land increased in all of the EPZs 

(fig. 16A) and ecoregions (not shown), and the response 

was similar in all areas except EPZ 1. The response in 

concentrations in EPZ 1 was less than in any other EPZ; 

however, this difference may simply reflect the limited 

distribution of the original data in EPZ 1. The standard 

errors in the estimates of coefficient b for the EPZs ranged 

from 0.13 to 0.16 compared to 0.20 to 0.44 for the level 

III ecoregions (table 9). As are result, the 95-percent 

confidence intervals for the EPZs were smaller than those 

for the ecoregions. Therefore, the EPZs provided better estimates of the response in SCHL concentrations to 

changes in the amount of agricultural land in the watershed 

than the level III ecoregions. Based on the similarity in 

the distribution of concentrations (fig. 15) and insignificant differences in values for coefficient b among EPZs, 

it is not appropriate to subdivide the wadeable streams of 

Wisconsin based on the response in SCHL concentrations 

to changes in nutrient concentrations and land use. 

Water clarity decreased as the percentage of agriculture land increased in all of the EPZs and level III ecoregions, and the response was similar in all areas except 

EPZ 1 (fig. 16B, shown for EPZs only). The water clarity 

decreased more slowly in EPZ 1 than in the other zones; 

however, there were only a few sites in EPZ 1 with extensive agriculture to support this conclusion. The response 

in water clarity in EPZ 3 was similar to the other areas; 

the difference in the water clarity in this area was caused 

by the lower reference clarity. The standard errors in the 

estimates of coefficient b for the EPZs ranged from 8.7 

to 16.1 compared to 13.7 to 21.5 cm for the ecoregions 

(table 9). Therefore, the EPZs provided better estimates of 

the response in SDs to changes in the amount of agricultural land in the watershed than the level III ecoregions. 

Based on the results for the EPZ regionalization scheme, 

subdividing wadeable streams into two categories seems 

appropriate: streams in areas with high clay-content soils 

(EPZ 3), which have a lower reference water clarity and 

clarity that decreases and remains lower than sites in the 

other areas as the percentage of agricultural land in the 

watershed increases, and streams in the rest of the State. 

Water Quality and Its Relations with Environmental Characteristics in the Watershed 45
46 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin Suspended chlorophyll 

a by environmental phosphorus zone

-0.5

2.01.51.00.50.0

-2.0 -1.5 -1.0 -0.5 0.0 0.5

LOG (TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER) LOG (TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER)

, A LOG (CHLOROPHYLL 

IN MICROGRAMS PER LITER)

, A LOG (CHLOROPHYLL 

IN MICROGRAMS PER LITER)

, A LOG (CHLOROPHYLL 

IN MICROGRAMS PER LITER)

, A LOG (CHLOROPHYLL 

IN MICROGRAMS PER LITER)

Suspended chlorophyll 

a by ecoregion

-0.5

2.01.51.00.50.0

-2.0 -1.5 -1.0 -0.5 0.0 0.5

Suspended chlorophyll 

a by ecoregion

-0.5

2.01.51.00.50.0

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

Suspended chlorophyll 

a by environmental phosphorus zone

-0.5

2.01.51.00.50.0

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTP

DFANCHFNLFSWTP

-1.158 (0.070 mg/L) -1.158 (0.070 mg/L)

0.068 (1.169 mg/L) 0.068 (1.169 mg/L)

Figure 14. Suspended chlorophyll a concentrations as a function of total phosphorus and total nitrogen concentration (logarithm to base 10 transformation), by environmental phosphorus zones (EPZs) and by level III ecoregions for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]
Secchi tube depth by environmental phosphorus zone

0

8604020

0

120100

-2.0 -1.5 -1.0 -0.5 0.0 0.5

LOG (TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER)

SECCHI TUBE DEPTH, IN CENTIMETERS

SECCHI TUBE DEPTH, IN CENTIMETERS

SECCHI TUBE DEPTH, IN CENTIMETERS

SECCHI TUBE DEPTH, IN CENTIMETERS

Secchi tube depth by environmental phosphorus zone

0

8604020

0

120100

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

Secchi tube depth by ecoregion

0

8604020

0

120100

-2.0 -1.5 -1.0 -0.5 0.0 0.5

LOG (TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER)

Secchi tube depth by ecoregion

0

8604020

0

120100

-1.0 -0.5 0.0 0.5 1.0 1.5

LOG (TOTAL NITROGEN, IN MILLIGRAMS PER LITER)

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTPDFANCHFNLFSWTP

-0.97 (0.106 mg/L) -0.97 (0.106 mg/L)

0.52 (3.305 mg/L) 0.52 (3.305 mg/L)

Figure 15. Secchi tube depth as a function of total phosphorus and total nitrogen concentration (logarithm to base 10 transformation), by environmental phosphorus zones 

(EPZs) and by level III ecoregions for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

Physical Habitat 47
Physical Habitat

The streams examined in this study exhibit considerable variation in their physical habitats, particularly with 

respect to mean stream widths and depths. Mean widths 

ranged from 1.1 m to over 55 m, with an overall mean 

width of 7.6 m (table 10). Mean depths ranged from 0.1 m 

to 1.0 m, with an overall mean depth of 0.3 m. Mean thalweg depths (deepest part of the cross section) ranged from 

0.1 m to 1.3 m, with an overall mean depth of 0.4 m. The 

gradients of the streams at the sampling sites ranged from 

nearly flat (0.0 m/km) to quite steep (up to 20.7 m/km) 

and their sinuosity (not in table 10) ranged from highly 

meandered to straight channels. About half of the streams 

contained well-developed runs. On average, 75 percent 

of the stream’s reach was classified as runs. Most streams 

had less than 10 percent of the reach classified as pools 

and riffles. Stream bottoms ranged from being almost 

completely silt to being dominated by sand or gravel. The 

percentage of the stream’s reach that was shaded ranged 

from 0 to 93.7 percent.

A. Response in suspended chlorophyll a

0

1

2

3

4

5

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

SUSPENDED CHLOROPHYLL 

A,

IN MILLIGRAMS PER LITER

B. Response in secchi tube depth

0

20

40

60

80

100

120

0 20 40 60 80 100

PERCENTAGE OF AGRICULTURAL LAND USE

SECCHI TUBE DEPTH, 

IN CENTIMETERS

EPZ 1

EPZ 2

EPZ 3

EPZ 4

All Data

EPZ 1

EPZ 2

EPZ 3

EPZ 4

All Data

Figure 16. Response curves for A, suspended chlorophyll 

a concentrations and B, Secchi tube depths in the 

environmental phosphorus zones (EPZs) as a function of the 

percentage of agriculture in the watershed for wadeable 

streams in Wisconsin.

48 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 10. Summary statistics for the physical-habitat characteristics and biotic indices for the studied wadeable streams in Wisconsin.

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; #, number; m, meter; m/km, meter per kilometer; mg/m2, milligram per square meter; log, logarithm to base 10 transformation; --, values are not indicative of 

water quality]

Characteristic/index Abbreviation Units Transformation Count Median Mean

Best 25th 

percentile 

of all sites

Standard 

deviation Minimum Maximum

Physical-habitat characteristics

Stream width WIDTH m none 235 4.5 7.6 -- 8.3 1.1 56.3Stream mean depth DEPTH m none 235 .3 .3 -- .2 .1 1.0Mean thalweg depth THALD m none 235 .4 .4 -- .2 .1 1.3Stream gradient GRAD m/km none 231 2.5 3.2 -- 3.0 .0 20.7Percentage of pools POOL% % none 234 5.0 10.5 -- 13.9 .0 100.0Percentage of riffle RIFF% % none 234 8.5 13.9 -- 17.2 .0 100.0Percentage of run RUN% % none 234 49.7 75.3 -- 22.9 .0 100.0Depth of sediment on stream bottom SEDEP m none 235 .1 .1 -- .1 .0 0.9Percentage of silt in bottom sediments SILT% % none 235 10.6 17.2 -- 18.3 .0 95.6Percentage of sand in bottom sediments SAND% % none 235 27.3 34.3 -- 25.3 .0 99.6Percentage of gravel in bottom sediments GRAV% % none 235 18.8 19.6 -- 14.5 .0 66.2Percentage of rocky-substrate embeddedness EMB% % none 235 64.2 59.8 -- 29.5 6.2 100.0Percentage of stream bottom covered by 

algae

ALGAE% % none 235 .4 4.8 -- 9.1 .0 53.8

Percentage of stream bottom covered by 

macrophytes

MACR% % none 235 1.3 6.3 -- 10.9 .0 54.8

Percentage of stream with fish cover COVER% % none 235 7.2 9.3 -- 9.2 .0 65.5Percentage of stream shaded SHADE% % none 235 28.9 33.9 -- 27.8 .0 93.7Percentage of stream bank with erosion EROSION% % none 235 12.5 17.7 -- 15.9 .0 76.5Buffer width BUFFER m none 235 10.5 12.6 -- 6.5 .0 30.0

Benthic chlorophyll a / diatoms

Benthic chlorophyll a BCHL mg/m2 log 199 1,919 12,879 552 80,884 7 1,068,000

Diatom Nutrient Index DNI # none 214 4.1 3.9 3.5 0.8 1.7 5.4Diatom Siltation Index DSI # none 214 38.2 39.9 16.7 24.9 2.6 95.3Diatom Biotic Index DBI # none 214 42.1 46.4 51.3 15.7 22.8 100.0

Physical Habitat 49
Characteristic/index Abbreviation Units Transformation Count Median Mean

Best 25th 

percentile 

of all sites

Standard 

deviation Minimum Maximum

Macroinvertebrates

Hilsenhoff Biotic Index HBI # none 227 4.7 4.9 4.0 1.6 0.8 9.4Percentage of EPT individuals EPTN% % none 227 42.3 41.0 61.8 26.1 .0 99.2Percentage of EPT taxa EPTTX% % none 227 35.7 33.9 45.7 16.8 .0 74.3Percentage of scrapers SCRAP% % none 227 14.7 19.0 29.5 18.0 .0 85.4Percentage of shredders SHRED% % none 227 0.0 1.0 -- 3.1 .0 24.7Number of taxa TAXAN # none 232 29 29.2 35.0 10.4 4 67

Fish

Fish Index of Biotic Integrity IBI # none 235 40.0 40.2 52.0 20.8 .0 100.0Percentage of carnivores CARN% % none 234 1.6 11.4 9.8 21.3 .0 100.0Percentage of insectivores INSECT% % none 234 48.9 49.8 29.1 24.2 .0 100.0Percentage of omnivores OMNI% % none 234 10.5 15.4 3.8 16.0 .0 81.1Percentage of intolerant species TOL% % none 234 3.3 14.6 15.8 23.3 .0 97.9Percentage of tolerant species INTOL% % none 234 42.8 41.5 19.5 25.6 .0 100.0Number of fish FISHN # log 234 130 199.6 -- 247.8 7 2,147Number of fish species FISHSPEC # none 235 11 11.5 -- 5.4 1 33

Table 10. Summary statistics for the physical-habitat characteristics and biotic indices for the studied wadeable streams in Wisconsin—Continued.[EPT, Ephemeroptera, Plecoptera, and Trichoptera; #, number; m, meter; m/km, meter per kilometer; mg/m2, milligram per square meter; log, logarithm to base 10 transformation; --, values are not indicative of 

water quality]

50 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Four indices were used to describe the benthic 

chlorophyll a and periphytic-diatom communities found 

in the streams in this study (table 10). Benthic chlorophyll a (BCHL) concentrations ranged from 7 mg/m2

to over 1,000,000 mg/m2 (median = 1,919 mg/m2), the 

Diatom Nutrient Index (DNI) values ranged from 1.7 

to 5.4 (median = 4.1), the Diatom Siltation Index (DSI) 

values ranged from 2.6 to 95.3 (median = 38.2), and 

Diatom Biotic Index (DBI) values ranged from 22.8 to 100 

(median = 42.1). In general, streams in the northern part 

of the State had lower BCHL concentrations and better 

quality diatom communities, lower DNI and DSI values, 

and higher DBI values than streams in the rest of the State 

(fig. 17). 

Relations with Individual Characteristics 

Correlations 

Spearman rank correlation coefficients (rs values) 

between the four indices describing BCHL and diatom 

communities and the water-quality, environmental, and 

physical-habitat characteristics are given in table 11. All 

four indices were significantly correlated with P and DP 

concentrations; however, only BCHL, DNI, and DSI were 

significantly correlated with N and NO3

-N concentrations. 

Only DNI and DSI were correlated with NH4-N, and only 

DNI was significantly correlated with TKN. The relations 

found for N were primarily the result of variability in 

NO3

-N concentrations, because N was computed as the 

sum of NO3-N and TKN, and TKN was only weakly correlated with most indices. DSI values were more strongly 

correlated with nutrient concentrations than were the 

Benthic Chlorophyll a and Periphytic-Diatom Communities 

and Their Relations with Water-Quality, Environmental, and 

Physical-Habitat Characteristics

Benthic Chlorophyll a and Periphytic-Diatom Communities and Their Relations 51

Wisconsin Department of Natural Resources personnel collecting diatom samples. Microscopic diatom pictures provided by Paul Garrison (Wisconsin 

Department of Natural Resources).
7 – 446

447 – 1,125

1,126 – 2,996

2,997 – 7,491

7,492 – 1,068,000

1.7 – 3.1

3.2 – 4.0

4.1 – 4.3

4.4 – 4.6

4.7 – 5.4

2.6 – 14.0

14.1 – 28.1

28.2 – 47.6

47.7 – 66.6

66.7 – 95.3

22.8 – 35.9

36.0 – 40.4

40.5 – 44.4

44.5 – 57.7

57.8 – 100.0

Concentrations,

in milligrams per 

square meter Index values

Index values Index values

Benthic chlorophyll a

(BCHL)

Diatom Nutrient Index

(DNI)

Diatom Biotic Index

(DBI)

Diatom Siltation Index

(DSI)

Figure 17. Distributions (quintiles) of benthic chlorophyll a (BCHL) concentrations, Diatom Nutrient Index (DNI) values, Diatom 

Siltation Index (DSI) values, and Diatom Biotic Index (DBI) values for the studied wadeable streams in Wisconsin.

52 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 11. Spearman rank correlation coefficients (rs

) between benthic chlorophyll a concentrations (BCHL) and diatom 

community indices, and median water-quality, environmental (anthropogenic/land-use, basin, soil and surficial-deposit), 

and physical-habitat characteristics for the studied wadeable streams in Wisconsin. 

[all bold values were significant at p < 0.05, after being adjusted for the Bonferroni correction (Zar, 1999); see table 10 on page 49 for definitions of 

abbreviations and units for each characteristic]

Characteristic

Benthic 

chlorophyll a

(BCHL)

Diatoms

Diatom Nutrient 

Index (DNI)

Diatom Siltation 

Index (DSI)

Diatom Biotic Index 

(DBI)

Water-quality characteristics

Total phosphorus 0.33 0.47 0.60 -0.46

Dissolved phosphorus .33 .47 .59 -.46

Total nitrogen .49 .36 .43 -.10

Dissolved nitrite plus nitrate .53 .31 .40 -.05

Dissolved ammonia .12 .21 .30 -.13

Total Kjeldahl nitrogen -.07 .24 .09 -.17

Suspended chlorophyll a .21 .24 .29 -.17

Secchi tube depth -.22 -.39 -.41 .17

Anthropogenic/land-use characteristics

Urban .25 .26 .10 .03

Agriculture (row crops) .44 .42 .42 -.13

Agriculture (all) .50 .44 .51 -.14

Grassland .10 .12 .20 -.14

Wetland (open) -.12 .18 -.22 -.02

Wetland (forested) -.44 -.18 -.51 .10

Forest (all) -.44 -.45 -.48 .17

Point-source loading of 

phosphorus

.27 .26 .18 -.17

Basin characteristics

Watershed area .10 .12 -.07 -.07

Air temperature .48 .42 .51 .00

Precipitation .21 .05 .28 .08

Runoff -.42 -.41 -.35 .00

Basin slope .28 .08 .48 -.15

Flow per unit area -.16 -.17 -.18 .15

Soil and surficial-deposit characteristics

Clay content .46 .44 .63 -.15

Erodibility .37 .37 .52 -.12

Organic-matter content -.41 -.14 -.55 .17

Permeability -.35 -.36 -.60 .25

Soil slope .06 -.25 .11 .08

Nonglacial deposits .42 -.01 .45 .03

Clay deposits .10 .30 .13 -.17

Loam deposits -.06 .02 .04 -.25

Peat deposits -.09 -.10 -.05 -.02

Sand deposits -.35 .00 -.34 .12

Sand-and-gravel deposits -.26 -.20 -.52 .24

Benthic Chlorophyll a and Periphytic-Diatom Communities 53
DNI values except for TKN, and both indices were more 

strongly correlated with nutrient concentrations than were 

DBI values. BCHL concentrations were more strongly correlated with the different forms of N, whereas the diatom 

indices were more strongly correlated with the different 

forms of P. Other studies have found the P-chlorophyll 

relation to be stronger than the N-chlorophyll relation (for 

example, Van Nieuwenhuyse and Jones, 1996). 

BCHL, DNI, and DSI were strongly correlated with 

SCHL, SD, and many of the anthropogenic/land-use 

characteristics, especially the percentages of total agriculture, row-crop agriculture, and forested areas. In addition, 

BCHL and the DNI were significantly correlated with the 

amount of urban land and PtS in the basin. Better index 

values (lower values for BCHL, DNI, and DSI) generally 

occurred in streams with lower SCHL and higher clarity, in 

areas with lower percentages of agriculture, less PtS, and 

higher percentages of forest. In general, these indices were 

also strongly correlated with several basin (air temperature 

and runoff) and soil (clay content, erodibility, organicmatter content, and permeability) characteristics. Lower 

BCHL concentrations and better diatom indices generally 

occurred in areas with cooler air temperatures, higher runoff, less erodible soils with lower clay content and higher 

permeability, and sand-and-gravel surficial deposits. These 

areas with lower BCHL concentrations and better diatom 

indices are the mixed and mostly forested areas of Wisconsin (fig. 2A).

In general, the BCHL and diatom indices were only 

weakly correlated with any physical-habitat characteristics 

except the percentage of the bottom covered in algae and 

the amount of sandy sediment. Better benthic diatom communities occurred in streams with lower percentages of 

algal cover. BCHL and the diatom indices were unrelated 

to the size or depth of the streams. 

Characteristic

Benthic 

chlorophyll a

(BCHL)

Diatoms

Diatom Nutrient 

Index (DNI)

Diatom Siltation 

Index (DSI)

Diatom Biotic Index 

(DBI)

Physical-habitat characteristics

WIDTH -0.03 -0.01 -0.17 -0.04

DEPTH .11 .00 .03 -.03

THALD .07 -.03 .01 -.03

GRAD .02 -.05 .13 .01

POOL% .00 -.04 .13 -.02

RIFF% .13 .13 .11 -.01

RUN% -.07 -.04 -.15 .05

SEDEP -.04 -.10 -.05 .01

SILT% .17 .05 .18 .06

SAND% -.29 -.18 -.22 -.02

GRAV% .00 .22 -.02 -.04

EMB% -.08 -.18 -.06 .04

ALGAE% .28 .21 .24 .02

MACR% .01 -.12 -.06 .12

COVER% -.12 -.10 -.19 .06

SHADE% -.07 .07 -.11 .00

EROSION% .18 .20 .32 -.15

BUFFER -.03 .09 -.07 .04

Table 11. Spearman rank correlation coefficients (rs) between benthic chlorophyll a concentrations (BCHL) and diatom 

community indices, and median water-quality, environmental (anthropogenic/land-use, basin, soil and surficial-deposit), 

and physical-habitat characteristics for the studied wadeable streams in Wisconsin—Continued. 

[all bold values were significant at p < 0.05, after being adjusted for the Bonferroni correction (Zar, 1999); see table 10 on page 49 for definitions of 

abbreviations and units for each characteristic]

54 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Responses to Changes in Nutrient 

Concentrations 

Responses in BCHL, DNI, and DSI to changes 

in nutrient concentrations are shown in figures 18 and 

19 (DBI values, which were computed on the basis of 

DNI and DSI values, were less strongly correlated with 

nutrient concentrations and therefore are not shown). In 

general, all three indices increased as nutrient concentrations increased, although the responses to changes in N 

concentrations ranged more widely than changes in P. 

At low nutrient concentrations, the values of the indices 

ranged widely; however, at high nutrient concentrations, 

the values were generally limited to high BCHL and poor 

diatom indices. High BCHL concentrations and poor 

diatom indices were measured even at low nutrient concentrations. The lower bounds of the BCHL and DNI plots 

may provide an indication of the extent to which nutrients 

are capable of limiting BCHL and the diatom community. 

The variation above these bounds may indicate the effects 

caused by factors other than nutrients. 

Although nutrient concentrations were lower or 

higher in some EPZs and level III ecoregions (especially 

lower in EPZ 1 and the NLF ecoregion), BCHL concentrations and diatom indices responded similarly to changes 

in nutrient concentrations in all areas (fig. 18). In all EPZs 

and ecoregions, there was a broad response at low nutrient 

concentrations and poor (higher) indices at high nutrient 

concentrations. Differences in the responses among areas 

could not be distinguished because of the range in the data 

and because the gradient in nutrient concentrations within 

many areas was small. 

Regression-tree analyses were done to define specific thresholds or breakpoints in the responses of BCHL 

concentrations and the diatom indices (table 12). The 

best statistical thresholds or breakpoints in the responses 

to changes in total P concentrations ranged from 0.039 

mg/L for BCHL concentrations to 0.057–0.074 mg/L for 

the diatom indices. Thresholds in the response to changes 

in DP concentrations ranged from 0.020 mg/L for BCHL 

to 0.046 mg/L for DSI. Thresholds in the responses to 

changes in the different forms of N are also listed in table 

12; however, the data in figures 18 and 19 do not show 

any consistent response except the DNI as a function of N. 

Thresholds in the responses to changes in N concentrations 

ranged from 0.872 to 1.216 mg/L. In general, sites with 

concentrations below the defined thresholds had a broad 

range in index values and sites above the defined threshold 

had poor index values, although the data do not indicate 

well-defined thresholds.

To examine further the thresholds or breakpoints in 

the responses of BCHL and the diatom indices to changes 

in nutrient concentrations, a categorical approach developed by the Ohio Environmental Protection Agency 

(OEPA; Miltner and Rankin, 1998) was used to examine 

the BCHL and DNI responses. With this approach, not 

only was the response to a single nutrient constituent 

examined but also the interaction of P and N. For this 

analysis, each of the sites having BCHL and diatom index 

data was placed into one of five categories based upon 

their percentile rankings for P and N concentrations (25th, 

50th, 75th, and 90th percentiles; table 13). The five categories in increasing nutrient concentrations are: category 1, 

sites that have both P and N concentrations less than their 

Table 12. Thresholds or breakpoints in the responses of benthic chlorophyll a (BCHL) concentrations and diatom indices to 

changes in nutrient concentrations for wadeable streams in Wisconsin. 

[all nutrient concentrations are in milligrams per liter; log, logarithm to base 10 transformation]

Biological Indices Total 

phosphorus

Dissolved 

phosphorus

Total 

nitrogen

Dissolved nitrite 

plus nitrate

Dissolved 

ammonia

Total Kjeldahl 

nitrogen

Benthic chlorophyll a (BCHL) - log 0.039 0.020 0.918 0.187 0.040 0.310

Diatom Nutrient Index (DNI) .057 .026 1.216 .381 .021 .745

Diatom Siltation Index (DSI) .074 .046 .872 .089 .022 1.080

Diatom Biotic Index (DBI) .072 .039 1.169 .381 .022 .388

Table 13. Percentiles of total phosphorus and total nitrogen 

concentration for the studied wadeable streams in Wisconsin 

having both benthic chlorophyll a and diatom index data.

[all concentrations in milligrams per liter] 

Percentile Total phosphorus Total nitrogen

25th 0.039 0.797

50th .071 1.724

75th .125 3.771

90th .203 7.447

Benthic Chlorophyll a and Periphytic-Diatom Communities 55
Benthic chlorophyll a Benthic chlorophyll a Benthic chlorophyll a Benthic chlorophyll a 7

6543210

0.0 0.2 0.4 0.6 0.8 1.0

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

, A LOG (BENTHIC CHLOROPHYLL 

IN MILLIGRAMS PER SQUARE METER)

Diatom Nutrient Index Diatom Nutrient Index Diatom Nutrient Index Diatom Nutrient Index 6

543210

0.0 0.2 0.4 0.6 0.8 1.0

DIATOM NUTRIENT INDEX

Diatom Siltation Index Diatom Siltation Index Diatom Siltation Index Diatom Siltation Index

0

755025

100

0.0 0.2 0.4 0.6 0.8 1.0

DIATOM SILTATION INDEX

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

76543210

0 5 10 15

6543210

0 5 10 15

0

755025

100

0 5 10 15

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

MEDIAN TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

76543210

0.0 0.2 0.4 0.6 0.8 1.0

6543210

0.0 0.2 0.4 0.6 0.8 1.0

0

755025

100

0.0 0.2 0.4 0.6 0.8 1.0

76543210

6543210

0

755025

100

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

0 5 10 15 20 25

0 5 10 15

0 5 10 15

DFANCHFNLFSWTPDFANCHFNLFSWTP

DFANCHFNLFSWTP

DFANCHFNLFSWTP

DFANCHFNLFSWTP

DFANCHFNLFSWTP

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

0.039 mg/L

1.641 mg/L 1.641 mg/L

1.641 mg/L

1.641 mg/L 1.641 mg/L 1.641 mg/L

21.260 mg/L 21.260 mg/L

21.260 mg/L

21.260 mg/L 21.260 mg/L 21.260 mg/L 0.057 mg/L

0.074 mg/L 0.074 mg/L

0.872 mg/L 0.872 mg/L

1.216 mg/L 1.216 mg/L

0.057 mg/L

0.039 mg/L 0.918 mg/L 0.918 mg/L

Figure 18. Benthic chlorophyll a concentrations (logarithm to base 10 transformation), Diatom Nutrient Index values, and Diatom Siltation Index values as a function of total phosphorus and total nitrogen concentration in the environmental phosphorus zones (EPZs) and level III ecoregions for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

56 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
0.040 mg/L 0.310 mg/L

0.745 mg/L 0.021 mg/L 0.381 mg/L 0.026 mg/L

0.046 mg/L

0.089 mg/L 1.080 mg/L 0.022 mg/L

Benthic chlorophyll a Benthic chlorophyll a Benthic chlorophyll a Benthic chlorophyll a 7

6543210

0.0 0.2 0.4 0.6 0.8 1.0

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

, A LOG (BENTHIC CHLOROPHYLL 

IN MILLIGRAMS PER SQUARE METER)

76543210

0 5 10 15

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

76543210

0.0 0.1 0.2 0.3 0.4 0.5

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

76543210

0.0 0.5 1.0 1.5 2.0 2.5

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

Diatom Nutrient Index Diatom Nutrient Index Diatom Nutrient Index Diatom Nutrient Index 6

543210

0.0 0.2 0.4 0.6 0.8 1.0

DIATOM NUTIENT INDEX

Diatom Siltation Index Diatom Siltation Index Diatom Siltation Index Diatom Siltation Index

0

755025

100

0.0 0.2 0.4 0.6 0.8 1.0

DIATOM SILTATION INDEX

6543210

0 5 10 15

0

755025

100

0 5 10 15

6543210

0.0 0.1 0.2 0.3 0.4 0.5

0

755025

100

0.0 0.1 0.2 0.3 0.4 0.5

6543210

0.0 0.5 1.0 1.5 2.0 2.5

0

755025

100

0.0 0.5 1.0 1.5 2.0 2.5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4

EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4

EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4

EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

0.020 mg/L 0.187 mg/L

1.460 mg/L 1.460 mg/L 1.460 mg/L

20.550 mg/L 20.550 mg/L 20.550 mg/L

Figure 19. Benthic chlorophyll a concentrations (logarithm to base 10 transformation), Diatom Nutrient Index values, and Diatom Siltation Index values as a function of dissolved phosphorus, dissolved nitrite plus nitrate, dissolved ammonia, and total Kjeldahl nitrogen concentrations in the environmental phosphorus zones (EPZs) for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines.

Benthic Chlorophyll a and Periphytic-Diatom Communities 57
25th percentiles; category 2, sites that are not in category 1 

and have either P or N concentrations less than their 50th 

percentiles; category 3, sites that are not in categories 1 or 

2 and have P concentrations less than its 75th percentile 

and N concentrations less than its 90th percentile; category 4, sites that are not in categories 1, 2, or 3 and have 

P concentrations between and including its 75th and 90th 

percentiles (N concentrations do not matter); and category 

5, sites that have both P and N concentrations greater than 

their 90th percentiles (OEPA also includes a sixth category 

for sites that have NH4

-N concentrations greater than 

1.0 mg/L but there were no such sites in this study.) 

Sites in category 1 (P concentrations less than 0.039 

mg/L and N concentrations less than 0.797 mg/L) had 

BCHL concentrations significantly less than those in 

categories 2 through 5 (fig. 20). BCHL concentrations 

increased slightly from category 2 to category 5; however, 

the differences were not statistically significant at 

p < 0.05. Sites in categories 1 and 2 (P concentrations 

less than 0.071 mg/L and N concentrations less than 

1.724 mg/L) had significantly lower (better) DNI values than those in categories 3 through 5. Therefore, the 

threshold in the response of the BCHL concentrations was 

at P concentrations less than about 0.04 mg/L and N less 

than about 0.8 mg/L, whereas the threshold in the response 

0

1

2

3

4

5

6

DIATOM NUTRIENT INDEX

12 3 45

NUTRIENT CATEGORY

12 3 45

NUTRIENT CATEGORY

0

1

2

3

4

5

6

LOG (BENTHIC CHLOROPHYLL 

A,

IN MILLIGRAMS PER LITER)

EXPLANATION

Outlier

Interquartile

range (IR)

75th percentile + 1.5 * IR

25th percentile – 1.5 * IR

75th percentile 

25th percentile 

Median

Figure 20. Benthic chlorophyll a concentrations and Diatom Nutrient Index values for five nutrient categories for the studied 

wadeable streams in Wisconsin (each nutrient category is defined in the text on pages 55 and 58).

58 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
in DNI values was at higher concentrations of P (less than 

about 0.07 mg/L) and N (less than about 1.7 mg/L). These 

thresholds are similar to those found from the regressiontree approach, except for the N threshold for the diatom 

community, which was less (about 1.2 mg/L; table 12) 

than the value found with this approach. 

The multimetric diatom index DBI was also tested as 

a means to define thresholds in the response of the diatom 

community to changes in nutrient concentrations. The DNI 

and DSI, however, provided more defined thresholds in the 

response of the diatom community to changes in nutrient 

concentrations, and, therefore, the DBI was not examined 

in further detail for this purpose. 

Effects of Multiple Characteristics on 

Benthic Chlorophyll a Concentrations and 

Diatom Indices

Stepwise Regressions

Forward stepwise regressions were done with the 

water-quality (median values), environmental, and physical-habitat characteristics to determine which four characteristics best described the variance in BCHL concentrations and the diatom indices (table 14). Models with 

more than four variables did not significantly increase the 

amount of variance explained (accumulative R2 values). 

For BCHL, NO3-N concentration was the first variable 

incorporated in the model, whereas DP concentration was 

the first variable incorporated in the DNI and DBI models. 

The clay content of the soil was the first variable incorporated in the DSI model, followed by P concentration. The 

clay content of the soil indicates the potential for siltation 

and, therefore, was expected to be an important variable in 

the DSI model. With four variables, the models explained 

between 31 and 60 percent of the total variance in the 

indices; therefore, 40 to 70 percent of the variance was not 

explained by the characteristics examined in this study.

Redundancy Analysis

Partial RDA was used to determine the relative importance of nutrients, other water-quality characteristics (pH, 

specific conductance, water clarity, and flow), and environmental and physical-habitat characteristics (tables 2 and 

10) in influencing the distribution of BCHL and the three 

diatom indices. In this analysis, individual monthly (July 

and August) and median values were included for each 

nutrient. A forward variable-selection procedure, which 

correlated the BCHL and the three diatom indices to the 

other factors, was used to select a subset of variables for 

each general type of characteristic. This procedure retained 

7 nutrient variables, 5 other water-quality characteristics, 

and 11 environmental and physical-habitat characteristics. 

These final 23 characteristics explained 54 percent of the 

variance in BCHL and the diatom indices. Of the explained 

variance, 13 percent was explained by the nutrients alone, 

4 percent by the other water-quality characteristics alone, 

46 percent by the environmental and physical-habitat characteristics alone, and 37 percent by the interactions among 

all the characteristics (fig. 21). Therefore, nutrient concentrations by themselves explained only a small part (about 

7 percent) of the total variance in BCHL and the diatom 

communities. About 46 percent of the total variance could 

not be explained with the characteristics examined in this 

study.

Table 14. Results of forward stepwise-regression analysis to explain the variance in benthic chlorophyll a concentrations and 

the three diatom indices in the studied wadeable streams in Wisconsin.

[R2, coefficient of determination for the one-, two-, three-, and four-variable models; all regressions were on log-transformed values of the dependant 

variable] 

Dependent variable First variable Second variable Third variable Fourth variable

Benthic chlorophyll a (BCHL) Nitrite plus nitrate Nonglacial deposits Loam deposits Runoff

 Accumulative R2 0.32 0.37 0.40 0.43

Diatom Nutrient Index (DNI) Dissolved phosphorus Wetland (forested) Percentage of pools Soil slope

 Accumulative R2 .25 .31 .33 .34

Diatom Siltation Index (DSI) Clay content of soil Total phosphorus Nonglacial deposits Grassland

 Accumulative R2 .42 .49 .59 .60

Diatom Biotic Index (DBI) Dissolved phosphorus Agriculture (row crops) Wetland (forested) Percentage of sand bottom

 Accumulative R2 .19 .25 .29 .31

Benthic Chlorophyll a and Periphytic-Diatom Communities 59
Reference Values for Benthic Chlorophyll a

Concentrations and Diatom Indices

A reference BCHL concentration and reference 

values for the three diatom indices were determined by 

examining the concentrations and index values at only the 

sites having both P and N concentrations at or below their 

respective reference concentrations (35 Reference sites). 

The median BCHL concentration for the Reference sites 

was 331 mg/m2 (log (331) = 2.52; the 75th percentile was 

673 mg/m2), which was significantly less than the median 

concentration measured at the High (nonreference) sites 

(3,020 mg/m2; log (3,020) = 3.48; fig. 22). The median 

DNI and DSI values for the Reference sites were 3.38 

and 11.80, respectively (with 75th percentiles of 4.05 and 

22.50, respectively), which were significantly less than the 

median values measured at the High sites (4.39 and 52.00, 

respectively). The median DBI value for the Reference 

sites was 47.5 (with a 25th percentile of 37.4; a lower 

percentile is given because a larger DBI represents a better 

diatom community), which was significantly greater than 

the median value measured at the High sites (39.9). If 75 

percent of the minimally impacted sites (the Reference 

sites) have water-quality conditions or index values at 

least as good as the reference condition, then the reference 

concentration for BCHL is 673 mg/m2

, and the reference 

index values for DNI, DSI, and DBI are 4.05, 22.5, and 

37.4, respectively. 

Comparing the median concentration and index 

values for the Reference sites with those for the Ref N and 

Ref P sites may provide an indication of whether P or N 

is more important in limiting the concentrations of BCHL 

and the degradation of the diatom community in streams 

with nutrient concentrations near reference conditions (fig. 

22). For BCHL, it appears that N is the more important 

limiting nutrient because the median value for the Ref P 

sites was significantly higher than the median value for 

the Reference sites, and there was no statistical difference between median values for Reference sites and the 

Ref N sites. In other words, small additions of N (Ref P) 

had more of an effect on BCHL concentrations than small 

additions of P (Ref N). Small additions of N also may have 

had a small effect on DSI values, although the median 

values for the categories were not significantly different. 

Small additions of P and N had little effect on DNI and 

DBI values in streams with nutrient concentrations near 

reference conditions. 

Nutrients

Other water-quality

 characteristics

Environmental and

 physical-habitat

 characteristics

Interactions

 among categories

13% 4%

37%

46%

General categories

Figure 21. Percentage of explained variance in benthic 

chlorophyll a concentrations and diatom index values 

described by nutrients, other water-quality characteristics, 

environmental (anthropogenic/land-use, soil, and surficialdeposit characteristics) and physical-habitat characteristics, 

and interactions among categories (variance that can not 

be explained by a single category) for the studied wadeable 

streams in Wisconsin. [%, percentage of explained variance]

60 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Reference High Ref N Ref P

0

20

40

60

80

100

DIATOM SILTATION INDEX

Reference High Ref N Ref P

0

1

2

3

4

5

6

7

LOG (BENTHIC CHLOROPHYLL 

A,

IN MILLIGRAMS PER SQUARE METER)

Reference High Ref N Ref P

0

1

2

3

4

5

6

DIATOM NUTRIENT INDEX

Reference High Ref N Ref P

0

20

40

60

80

100

DIATOM BIOTIC INDEX

EXPLANATION

Outlier

Interquartile

range (IR)

75th percentile + 1.5 * IR

25th percentile – 1.5 * IR

75th percentile 

25th percentile 

Median

Figure 22. Benthic chlorophyll a concentrations, Diatom Nutrient Index, Diatom Siltation Index, and Diatom Biotic Index 

values in Reference sites, High (nonreference) sites, and sites with only reference total nitrogen (Ref N sites) or reference total 

phosphorus (Ref P sites) concentrations in the studied wadeable streams in Wisconsin. [log, logarithm to base 10 transformation]

Benthic Chlorophyll a and Periphytic-Diatom Communities 61
Six indices were used to describe the macroinvertebrate communities in the studied wadeable streams in 

Wisconsin (table 10 on page 50). Hilsenhoff Biotic Index 

(HBI) values ranged from 0.8 to 9.4 (median = 4.7); the 

percentage of individuals that were either Ephemeroptera, 

Plecoptera, or Trichoptera (EPTN%) varied from 0.0 to 

99.2 percent (median = 42.3 percent); the percentage of 

taxa that were Ephemeroptera, Plecoptera, or Trichoptera 

(EPTTX%) varied from 0.0 to 74.3 percent (median = 35.7 

percent); the percentage of the individuals that were scrapers (SCRAP%) varied from 0.0 to 85.4 percent (median 

= 14.7 percent); the percentage of individuals that were 

shredders (SHRED%) varied from 0.0 to 24.7 percent 

(median = 0.0 percent), and the total numbers of taxa 

(TAXAN) varied from 4 to 67 (median = 29). In general, 

streams in the northern part of the State had macroinvertebrate communities that would normally be considered 

representative of better water quality, with lower HBI 

values, higher EPTN% and EPTTX% (fig. 23), and higher 

TAXAN than the streams in the southeastern part of the 

State. The SCRAP% and SHRED% did not exhibit strong 

regional patterns. 

Relations with Individual Characteristics 

Correlations 

Spearman rank correlation coefficients (rs values) 

between the six macroinvertebrate indices and median 

water-quality, environmental, and physical-habitat characteristics are given in table 15. All six indices were significantly correlated with at least two nutrient constituents. 

Of the six macroinvertebrate indices, HBI, EPTN%, and 

EPTTX% were most strongly correlated with the nutrients. 

HBI and EPTN% were significantly correlated with all of 

the nutrients except NO3

-N. SCRAP% and TAXAN were 

negatively correlated with most nutrients, although many 

of the correlations were not statistically significant. Concentrations of P and N were positively correlated with HBI 

values and negatively correlated with EPTN%, EPTTX%, 

and TAXAN. Better macroinvertebrate indices (lower HBI 

values, higher EPT indices, and more taxa) occurred with 

lower nutrient concentrations. The SCRAP%, SHRED%, 

and TAXAN were less strongly correlated with most 

nutrient concentrations. Individual monthly nutrient 

Macroinvertebrate Communities and Their Relations 

with Water-Quality, Environmental, and Physical-Habitat 

Characteristics

62 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Wisconsin Department of Natural Resources personnel collecting macroinvertebrate samples. Macroinvertebrate pictures provided by Stanley Szczytko 

(University of Wisconsin–Stevens Point).
0.8 – 3.7

3.8 – 4.4

4.5 – 5.0

5.1 – 6.0

6.1 – 9.4

0 – 11.4

11.5 – 32.6

32.7 – 49.4

49.5 – 68.4

68.5 – 99.2

0 – 17.2

17.3 – 31.8

31.9 – 38.0

38.1 – 50.0

50.1 – 74.3

Index values Percentages

Percentages

Hilsenhoff

Biotic Index

(HBI)

Percentage of 

EPT individuals

(EPTN%)

Percentage of EPT taxa

(EPTTX%)

Figure 23. Distributions (quintiles) of macroinvertebrate Hilsenhoff Biotic Index (HBI) values, the percentages of individuals that 

were Ephemeroptera, Plecoptera, or Trichoptera (EPTN%), and the percentages of taxa that were Ephemeroptera, Plecoptera, or 

Trichoptera (EPTTX%) for the studied wadeable streams in Wisconsin.

Macroinvertebrate Communities 63
Table 15. Spearman rank correlation coefficients (rs

) between macroinvertebrate-community indices and median water-quality, 

environmental (anthropogenic/land-use, basin, soil and surficial-deposit), and physical-habitat characteristics for the studied

wadeable streams in Wisconsin. 

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; %, percent; all bold values were significant at p < 0.05, after being adjusted for the Bonferroni 

correction (Zar, 1999); see table 10 on page 49 for definitions of abbreviations and units for each parameter]

Characteristic Hilsenhoff 

Biotic Index

Percentage of 

EPT individuals

Percentage 

of EPT taxa

Percentage 

of scrapers

Percentage of 

shredders

Number 

of taxa

Water-quality characteristics

Total phosphorus 0.55 -0.35 -0.46 -0.21 0.09 -0.19

Dissolved phosphorus .50 -.33 -.43 -.18 .06 -.18

Total nitrogen .37 -.37 -.39 -.10 -.06 -.30

Dissolved nitrite plus nitrate .16 -.24 -.20 .03 -.21 -.28

Dissolved ammonia .53 -.39 -.54 -.21 .12 -.27

Total Kjeldahl nitrogen .54 -.28 -.44 -.28 .30 -.10

Suspended chlorophyll a .42 -.27 -.33 -.04 .18 .04

Secchi tube depth -.41 .29 .34 .17 -.11 .23

Anthropogenic/land-use characteristics

Urban .16 -.10 -.03 .00 .06 -.08

Agriculture (row crops) .45 -.42 -.45 -.07 -.04 -.33

Agriculture (all) .43 -.38 -.42 -.02 -.06 -.31

Grassland -.12 -.02 .08 .18 -.22 -.15

Wetland (open) .17 -.07 -.11 -.08 .22 .04

Wetland (forested) .04 .11 .04 -.14 .25 .16

Forest (all) -.48 .42 .48 .08 .01 .30

Point-source loading of 

phosphorus

.14 .05 .05 -.05 .11 .03

Basin characteristics

Watershed area -.13 .24 .17 .05 .09 .23

Air temperature .36 -.33 -.33 .01 -.13 -.30

Precipitation -.08 -.03 .11 .25 -.21 -.09

Runoff -.32 .27 .26 -.01 .14 .27

Basin Slope -.15 .11 .15 .18 -.26 -.11

Flow per unit area -.30 .22 .27 .17 -.09 .08

Soil and surficial-deposit characteristics

Clay content .24 -.26 -.24 .07 -.10 -.31

Erodibility .29 -.24 -.28 .07 -.07 -.21

Organic-matter content .05 .02 -.02 -.21 .31 .13

Permeability -.20 .20 .22 -.05 .06 .21

Soil slope -.39 .28 .42 .23 -.23 .13

Nonglacial deposits -.10 .05 .09 .18 -.18 -.03

Clay deposits .24 -.19 -.22 -.16 .10 -.09

Loam deposits .04 .09 .04 .03 -.03 .00

Peat deposits .09 -.06 -.13 -.19 .24 .01

Sand deposits .02 -.03 -.01 -.08 .17 .09

Sand-and-gravel deposits -.14 .13 .15 -.07 .07 .11

64 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Characteristic Hilsenhoff 

Biotic Index

Percentage of 

EPT individuals

Percentage 

of EPT taxa

Percentage 

of scrapers

Percentage of 

shredders

Number 

of taxa

Physical-habitat characteristics

WIDTH -0.20 0.35 0.25 0.09 0.11 0.31

DEPTH .00 .13 .04 .00 .12 .10

THALD -.04 .17 .07 .00 .13 .14

GRAD -.16 .01 .11 .19 -.26 -.08

POOL% -.16 .07 .10 .19 -.17 .03

RIFF% -.26 .23 .28 .28 -.28 .01

RUN% .25 -.19 -.25 -.28 .26 -.04

SEDEP .20 -.20 -.26 -.27 .15 -.08

SILT% .41 -.32 -.43 -.15 .09 -.11

SAND% -.18 .06 .16 -.05 -.03 .12

GRAV% -.25 .24 .28 .30 -.22 .04

EMB% .26 -.26 -.30 -.31 .15 -.05

ALGAE% .25 -.15 -.23 .04 -.05 -.13

MACR% .16 -.08 -.15 -.14 .13 .15

COVER% .06 .01 -.07 -.12 .21 .16

SHADE% -.09 .04 .05 .00 -.19 -.15

EROSION% .02 -.03 .00 .06 -.21 -.18

BUFFER .05 -.07 -.05 -.04 .08 -.14

Table 15. Spearman rank correlation coefficients (rs) between macroinvertebrate-community indices and median water-quality, 

environmental (anthropogenic/land-use, basin, soil and surficial-deposit), and physical-habitat characteristics for the studied

wadeable streams in Wisconsin—Continued. 

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; %, percent; all bold values were significant at p < 0.05, after being adjusted for the Bonferroni 

correction (Zar, 1999); see table 10 on page 49 for definitions of abbreviations and units for each parameter]

Macroinvertebrate Communities 65
concentrations were examined, but in all cases the monthly 

values explained less variance than the median values.

In general, HBI, EPTN%, and EPTTX% were also 

the indices most strongly correlated with SCHL, SD, and 

the anthropogenic/land-use characteristics, especially 

the percentages of total agriculture, row-crop agriculture, and forested areas. Better macroinvertebrate indices 

(lower HBIs and higher EPT indices) generally occurred 

in streams with lower SCHL and higher clarity, in areas 

with lower percentages of agriculture and higher percentages of forest. SCRAP%, SHRED%, and TAXAN were 

less strongly correlated with the anthropogenic/land-use 

characteristics. HBI, EPTN%, and EPTTX% were also 

more strongly correlated with the basin characteristics (air 

temperature, runoff, and flow per unit area) and the soil 

and surficial-deposit characteristics (clay content of the 

soil, erodibility, soil slope, and clay deposits) than were 

the other three macroinvertebrate indices. In general, better 

macroinvertebrate communities were found in areas with 

cooler air temperatures, higher runoff, soils with lower 

clay content, and higher soil slope. These areas with better 

macroinvertebrate indices are generally the mixed and 

mostly forested areas of Wisconsin (fig. 2A).

In general, the macroinvertebrate indices were only 

moderately correlated with the physical-habitat characteristics. The physical-habitat characteristics that were most 

strongly correlated with macroinvertebrate indices were the 

percentages of rocky-substrate embeddedness, percentages 

of riffles and runs, and percentages of silt and gravel sediment. Better macroinvertebrate communities were found in 

wider streams with lower percentages of runs, rocky-substrate embeddedness, and silt sediment, and higher percentages of riffles and gravel substrate. Many macroinvertebrate 

samples were collected in areas of the stream with physical-habitat characteristics that were substantially different from the average characteristics for the entire stream 

reach. Improved correlations between the physical-habitat 

characteristics and the macroinvertebrate indices would 

have probably occurred if the habitat characteristics were 

estimated for only the area near the macroinvertebrate-sampling location. 

Response to Changes in Nutrient 

Concentrations 

Responses in the three macroinvertebrate community indices most strongly correlated with nutrients (HBI, 

EPTN%, and EPTTX%) are shown in figures 24 and 25. 

In general, HBI values increased as nutrient concentrations increased, whereas EPTN% and EPTTX% values 

decreased or showed no clear trend with increases in 

nutrient concentrations. At low nutrient concentrations, the 

values of these macroinvertebrate measures ranged widely; 

however, at high nutrient concentrations, the values were 

generally poor (high HBI values and low EPT indices). 

The best relations were found between HBI values and 

P, DP, and TKN concentrations, and between both EPT 

indices and P, DP, and NH4

-N concentrations. The other 

relations with nutrient concentrations ranged more widely; 

little relation was found between both EPT indices and 

N, TKN, and NO3-N concentrations. The lower bounds of 

HBI plots and the upper bounds of the EPT plots may provide an indication of how nutrients are capable of affecting 

the macroinvertebrate community. The variation below the 

HBI bounds and above the EPT bounds may indicate the 

effects caused by factors other than nutrients.

Although nutrient concentrations were lower or 

higher in some EPZs and ecoregions (especially lower in 

EPZ 1 and the NLF ecoregion), macroinvertebrate indices 

responded similarly to changes in nutrient concentrations in all areas of the State (fig. 24). In all areas, there 

was a broad response at low nutrient concentrations and 

poor indices at high nutrient concentrations. Differences 

in the responses among areas could not be distinguished 

because of the range of the data and because the gradient 

in nutrient concentrations within some areas was small. 

Regression-tree analyses were performed to define 

specific thresholds or breakpoints in the responses of the 

three macroinvertebrate community indices most strongly 

correlated with nutrients (table 16). The thresholds or 

breakpoints in the responses to changes in most nutrient 

concentrations were consistent among these three indices, 

although the data do not indicate well-defined thresholds. 

The thresholds in the responses to changes in total P 

concentrations were at about 0.09 mg/L, to changes in DP 

concentrations were at about 0.06–0.08 mg/L, to changes 

in total N concentrations were from 0.609 to 1.106 mg/L 

(the lowest threshold value occurred for HBI), to changes 

in NH4

-N concentrations were at about 0.03 mg/L, and to 

changes in TKN concentrations were at about 1.0 mg/L. 

The range in the thresholds to changes in NO3-N concentrations was broader (from 1.157 to 3.585 mg/L). In general, the macroinvertebrate indices ranged widely below 

the thresholds; however, macroinvertebrate indices were 

poor above the thresholds.

66 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
0.088 mg/L 0.088 mg/L

1.641 mg/L 1.641 mg/L 1.641 mg/L

1.641 mg/L 1.641 mg/L 1.641 mg/L

21.260 mg/L 21.260 mg/L 21.260 mg/L

21.260 mg/L 21.260 mg/L 21.260 mg/L

0.609 mg/L 0.609 mg/L

0.907 mg/L 0.907 mg/L 0.087 mg/L 0.087 mg/L

0.091 mg/L 0.091 mg/L 1.106 mg/L 1.106 mg/L

Hilsenhoff Biotic Index

9876543210

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MEDIAN TOTAL PHOSPHORUS,

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

HILSENHOFF BIOTIC INDEX

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EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

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DFANCHFNLFSWTPDFANCHFNLFSWTP

DFANCHFNLFSWTP

DFANCHFNLFSWTPDFANCHFNLFSWTPDFANCHFNLFSWTP

Figure 24. Hilsenhoff Biotic Index values, the percentages of individuals that were Ephemeroptera, Plecoptera, or Trichoptera, and the percentages of taxa that were Ephemeroptera, Plecoptera, or Trichoptera as a function of total phosphorus and total nitrogen concentration in the environmental phosphorus zones (EPZs) and level III ecoregions for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

Macroinvertebrate Communities 67
0.077 mg/L 3.455 mg/L

1.460 mg/L 1.460 mg/L 1.460 mg/L

20.550 mg/L 20.550 mg/L 20.550 mg/L 0.029 mg/L 0.965 mg/L 1.053 mg/L 0.029 mg/L 0.077 mg/L 0.061 mg/L 3.585 mg/L 0.034 mg/L 0.930 mg/L 1.157 mg/L

Hilsenhoff Biotic Index Hilsenhoff Biotic Index Hilsenhoff Biotic Index Hilsenhoff Biotic Index

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

0 5 10 15 0.0 0.1 0.2 0.3 0.4 0.5 0.0 0.5 1.0 1.5 2.0 2.5

0.0 0.2 0.4 0.6 0.8 1.0

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

0 5 10 15 0.0 0.1 0.2 0.3 0.4 0.5 0.0 0.5 1.0 1.5 2.0 2.5

0

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90

100

PERCENTAGE OF EPT INDIVIDUALS

Percentage of EPT taxa Percentage of EPT taxa Percentage of EPT taxa Percentage of EPT taxa

0

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PERCENTAGE OF EPT TAXA

0

870605040302010

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0

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0

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0

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0

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0

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EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

Figure 25. Hilsenhoff Biotic Index values, the percentages of individuals that were Ephemeroptera, Plecoptera, or Trichoptera, and the percentages of taxa that were Ephemeroptera, Plecoptera, or Trichoptera as a function of dissolved phosphorus, dissolved nitrite plus nitrate, dissolved ammonia, and total Kjeldahl nitrogen concentrations in the environmental phosphorus zones (EPZs) for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines.

68 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Effects of Multiple Characteristics on 

Macroinvertebrate Indices

Stepwise Regressions

Forward stepwise regressions were done with the 

median water-quality, environmental, and physical-habitat 

characteristics to determine which four characteristics best 

described the variance in the macroinvertebrate indices 

(table 17). Models with more than four variables did not 

significantly increase the amount of variance explained 

(accumulative R2 value). For most indices, either a nutrient 

or the percentage of forest/agriculture was the first variable incorporated in the models, except for the SCRAP% 

and SHRED% that were found to be weakly correlated 

with nutrient concentrations. Even with four variables, the 

models explained only 19 to 47 percent of the variance in 

the indices. The stepwise regressions explained the most 

variance in the same three macroinvertebrate indices (HBI, 

EPTN%, and EPTTX%) that were most related to the 

nutrients and environmental characteristics. The SHRED% 

model appears to have better predictability than the percent 

variance explained indicates because most of the values for 

SHRED% were 0.

Table 17. Results of forward stepwise-regression analyses to explain variance in macroinvertebrate indices for the studied 

wadeable streams in Wisconsin. 

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; R2, coefficient of determination for the one-, two-, three-, and four-variable models]

Dependent variable First variable Second variable Third variable Fourth variable

Hilsenhoff Biotic Index 

(HBI)

Dissolved ammonia Flow per unit area Percentage of 

macrophyte cover

Total phosphorus

Accumulative R2 0.31 0.38 0.43 0.47

Percentage of EPT individuals 

(EPTN%)

Forest (all) Percentage of rockysubstrate embeddednessStream depth Organic-matter 

content

Accumulative R2 .19 .28 .32 .35

Percentage of EPT taxa 

(EPTTX%)

Dissolved ammonia Agriculture (row crops) Percentage of rockysubstrate embeddednessFlow per unit area

Accumulative R2 .26 .35 .42 .45

Percentage of scrapers 

(SCRAP%)

Precipitation Sediment depth Total phosphorus Percentage of 

macrophyte cover

Accumulative R2 .07 .12 .16 .19

Percentage of shredders 

(SHRED%)

Peat deposits Kjeldahl nitrogen Percentage of 

streambank with erosion

Percentage of silt

Accumulative R2 .30 .35 .38 .41

Number of taxa 

(TAXAN)

Total nitrogen Watershed area Clay deposits Buffer width

Accumulative R2 .14 .17 .20 .22

Macroinvertebrate Communities 69

Table 16. Thresholds or breakpoints in the responses in macroinvertebrate indices to changes in nutrient concentrations for 

wadeable streams in Wisconsin.

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; all concentrations are in milligrams per liter]

Biological indices Total 

phosphorus

Dissolved 

phosphorus

Total 

nitrogen

Dissolved nitrite 

plus nitrate

Dissolved 

ammonia

Total Kjeldahl 

nitrogen

Hilsenhoff Biotic Index (HBI) 0.088 0.077 0.609 3.455 0.029 0.965

Percentage of EPT individuals 

(EPTN%)

.087 .077 .970 1.157 .029 1.053

Percentage of EPT taxa (EPTTX%) .091 .061 1.106 3.585 .034 .938
Redundancy Analysis

Partial RDA was used to determine the relative importance of the nutrients, other water-quality characteristics, 

and environmental and physical-habitat characteristics 

(tables 2 and 10) in affecting the distribution of the macroinvertebrate communities (the six macroinvertebrate-community indices). In this analysis, individual monthly (July 

and August) and median values were included for each 

nutrient. A forward variable-selection procedure, which 

correlated the macroinvertebrate indices with the other 

factors, was used to select a subset of variables for each 

general type of characteristic. This procedure retained 9 

nutrient variables, 3 other water-quality characteristics, 

and 17 environmental and physical-habitat characteristics. These 29 characteristics explained 43 percent of the 

variance in the six macroinvertebrate-community indices. 

Of the explained variance, 22 percent was described by 

the nutrients alone, 5 percent by the other water-quality 

characteristics alone, 41 percent by the environmental 

and physical-habitat characteristics alone, and 32 percent 

by the interactions among all the characteristics (fig. 26). 

Therefore, nutrient concentrations by themselves explained 

only a small part (about 10 percent) of the total variance 

in the macroinvertebrate communities. About 57 percent 

of the total variance could not be explained by the characteristics examined in this study, and 14 percent of the total 

variance could not be separated into a single category of 

characteristics. 

Reference Values for the Macroinvertebrate 

Indices

Reference values for the three macroinvertebrate indices most related to nutrient concentrations (HBI, EPTN%, 

and EPTTX%) were determined by examining the index 

values at only the sites having both P and N concentrations 

at or below their respective reference concentrations. The 

median HBI value for the Reference sites was 3.1 (with 

a 75th-percentile value of 4.4), which was significantly 

less than the median value at the High (nonreference) sites 

(5.1; fig. 27). The median reference EPTN% and EPTTX% 

values were 60 and 50 percent, respectively (with 25thpercentile values of 51 and 38 percent, respectively; lower 

percentiles are given for these indices because larger 

values represent better macroinvertebrate communities), 

which were significantly more than the median values 

measured at the High sites (33 and 31 percent, respectively). If 75 percent of the minimally impacted sites (the 

Reference sites) have index values at least as good as the 

reference condition, then the reference index values for 

HBI, EPTN%, and EPTTX% are 4.4, 51 percent, and 38 

percent, respectively. 

Comparing the median index values for the Reference sites with those for the Ref N and Ref P sites may 

provide an indication of whether P or N is more important 

in the degradation of the macroinvertebrate community 

in streams with nutrient concentrations near reference 

conditions (fig. 27). For all three indices, it appears that N 

is the more important limiting nutrient because the median 

values for the Ref P sites were significantly higher (HBI) 

or lower (EPTN% and EPTTX%) than the median values 

for the Reference sites. There were no differences between 

median values for Reference sites and the Ref N sites. 

Small additions of N (Ref P) had more of an effect on the 

macroinvertebrate communities than small additions of P 

(Ref N) for sites with nutrient concentrations near reference conditions. 

Nutrients

Other water-quality

 characteristics

Environmental and

 physical-habitat

 characteristics

Interactions among

 categories

22%

5%

32%

41%

General categories

Figure 26. Percentages of explained variance in six 

macroinvertebrate index values described by nutrients, other 

water-quality characteristics, environmental (anthropogenic/

land-use, soil, and surficial-deposit characteristics) and 

physical-habitat characteristics, and interactions among 

categories (variance that can not be explained by a single 

category) for the studied wadeable streams in Wisconsin. [%, 

percentage of explained variance]

70 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Reference High Ref N Ref P

0

2

4

6

8

10

HILSENHOFF BIOTIC INDEX

Reference High Ref N Ref P

0

20

40

60

80

100

PERCENTAGE OF EPT INDIVIDUALS

Reference High Ref N Ref P

0

20

40

60

80

100

PERCENTAGE OF EPT TAXA

EXPLANATION

Outlier

Interquartile

range (IR)

75th percentile + 1.5 * IR

25th percentile – 1.5 * IR

75th percentile 

25th percentile 

Median

Figure 27. Hilsenhoff Biotic Index values, the percentages of individuals that were Ephemeroptera, Plecoptera, or Trichoptera, 

and the percentages of taxa that were Ephemeroptera, Plecoptera, or Trichoptera in Reference sites, High (nonreference) sites, 

and sites with only reference total nitrogen (Ref N sites) or reference total phosphorus (Ref P sites) concentrations in the studied 

wadeable streams in Wisconsin.

Macroinvertebrate Communities 71
The streams examined had a wide range in fish communities. Eight indices were used to describe the fish communities (table 10 on page 50). Fish Index of Biotic Integrity (IBI) values ranged from 0.0 to 100.0 (median = 40.0). 

The percentages of fish considered carnivores (CARN%) 

and insectivores (INSECT%) ranged from 0.0 to 100.0 

percent (median = 1.6 and 48.9 percent, respectively). 

The percentages of fish considered omnivores (OMNI%) 

ranged from 0.0 to 81.1 percent (median = 10.5 percent). 

The percentages of fish considered pollution intolerant 

(INTOL%) ranged from 0.0 to 97.9 percent (median = 3.3 

percent), and the percentage of fish considered pollution 

tolerant (TOL%) ranged from 0.0 to 100.0 percent (median 

= 42.8 percent). The number of fish caught (FISHN) 

ranged from 7 to 2,147 fish (median = 130). The number 

of species of fish caught (FISHSPEC) ranged from 1 to 33 

species (median = 11). Streams in the northern and central 

parts of the State generally had higher IBI, INTOL%, and 

CARN% than streams in other parts of the State (fig. 28). 

The INSECT%, OMNI%, TOL%, FISHN, and FISHSPEC 

did not exhibit strong regional patterns. 

Relations with Individual Characteristics 

Correlations 

Spearman rank correlation coefficients between the 

eight fish indices and median water-quality, environmental, and physical-habitat characteristics are shown in table 

18. All eight indices were significantly correlated with at 

least one nutrient constituent. IBI, CARN%, and INTOL% 

values were most strongly correlated with most nutrients. 

OMNI% and TOL% values were also significantly correlated with some nutrients, but less strongly correlated than 

these three indices. The other three indices (INSECT%, 

FISHSPEC, and FISHN) were significantly correlated 

with only NH4

-N, TKN, or DP. In general, the fish indices 

indicative of better conditions (higher IBI, CARN%, 

INTOL% values) occurred with lower nutrient concentrations. Concentrations of NO3

-N were significantly correlated with the smallest number of fish indices. Individual 

monthly nutrient concentrations were also examined, but 

in all cases explained less variance than the median values.

In general, IBI, CARN%, INTOL%, OMNI%, and 

FISHAB were the indices most strongly correlated with 

Fish Communities and Their Relations with Water-Quality, 

Environmental, and Physical-Habitat Characteristics

72 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Wisconsin Department of Natural Resources personnel collecting fish with electrofishing gear. Fish pictures provided by Michael Miller and John Lyons 

(Wisconsin Department of Natural Resources).
0 – 25

26 – 35

36 – 45

46 – 60

61 – 100

0

0.1 – 2.4

2.5 – 8.7

8.8 – 23.1

23.2 – 97.9

0

0.1 – 1.4

1.5 – 5.2

5.3 – 19.3

19.4 – 100

6 – 45

46 – 93

94 – 170

171 – 288

289 – 2,147

Index values Percentages

Percentages Number of fish

Fish Index of 

Biotic Integrity

(IBI)

Percentage of 

carnivorous fish

(CARN%)

Number of 

fish caught

(FISHN)

Percentage of 

intolerant fish

(INTOL%)

Figure 28. Distributions (quintiles) of fish Index of Biotic Integrity (IBI) values, the percentages of the fish that are carnivorous 

(CARN%), the percentages of fish considered pollution intolerant (INTOL%), and the number of fish caught (FISHN) for the studied 

wadeable streams in Wisconsin.

Fish Communities 73
Table 18. Spearman rank correlation coefficients (rs

) between fish-community indices and median water-quality, environmental 

(anthropogenic/land-use, basin, soil, and surficial-deposit), and physical-habitat characteristics for the studied wadeable streams 

in Wisconsin.

[all bold values were significant at p < 0.05, after being adjusted for the Bonferroni correction (Zar, 1999); see table 10 on page 49 for definitions of 

abbreviations and units for each parameter]

Characteristic

Fish Index 

of Biotic 

Integrity

Percentage of 

carnivores

Percentage 

of 

insectivores

Percentage of 

omnivores

Percentage 

of intolerant species

Percentage 

of tolerant 

species

Number of 

fish 

species

Number 

of fish

Water-quality characteristics

Total phosphorus -0.33 -0.42 0.13 0.23 -0.36 0.24 0.12 0.18

Dissolved phosphorus -.29 -.41 .09 .21 -.36 .22 .12 .23

Total nitrogen -.31 -.29 .09 .26 -.31 .08 -.07 .14

Dissolved nitrate plus 

nitrite

-.20 -.14 -.04 .27 -.17 -.04 -.10 .12

Dissolved ammonia -.27 -.46 .23 .16 -.39 .29 .04 .16

Total Kjeldahl nitrogen -.25 -.43 .29 .11 -.40 .36 .24 .08

Suspended chlorophyll a -.04 -.28 .18 .26 -.20 .03 .33 .15

Secchi tube depth .32 .36 -.11 -.29 .38 -.17 -.05 .01

Anthropogenic/land-use characteristics

Urban .03 .10 .13 .15 .04 -.05 .12 -.17

Agriculture (row crops) -.25 -.37 .13 .26 -.41 .13 .03 .22

Agriculture (all) -.26 -.36 .09 .29 -.37 .09 .04 .27

Grassland .06 .00 -.02 .07 .09 -.03 -.07 -.01

Wetland (open) .14 -.09 .30 .05 .00 .06 .34 -.08

Wetland (forested) .13 .04 .19 -.22 .05 .12 .16 -.21

Forest (all) .28 .39 -.11 -.31 .40 -.13 -.05 -.24

Point-source loading of 

phosphorus

.09 .16 .05 .21 .11 -.11 .30 -.23

Basin characteristics

Watershed area .26 .34 .08 .24 .25 -.25 .47 -.20

Air temperature -.32 -.30 .04 .35 -.42 .15 -.05 .25

Precipitation -.15 -.06 -.17 .20 -.12 .02 -.05 .14

Runoff .26 .26 -.11 -.28 .37 -.16 .04 -.17

Basin slope -.12 .05 -.22 .10 -.01 -.04 -.18 .12

Unit area flow .07 .08 -.06 -.09 .20 .03 -.02 .02

74 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Characteristic

Fish Index 

of Biotic 

Integrity

Percentage of 

carnivores

Percentage 

of 

insectivores

Percentage of 

omnivores

Percentage 

of intolerant species

Percentage 

of tolerant 

species

Number of 

fish 

species

Number 

of fish

Soil and surficial-deposit characteristics

Clay content -.27 -.25 -.02 .26 -.33 .09 -.05 .23

Erodibility -.28 -.35 -.05 .28 -.35 .10 .07 .38

Organic-matter content .16 .12 .18 -.18 .04 .05 .10 -.25

Permeability .26 .27 .11 -.20 .26 -.10 .01 -.29

Soil slope .05 .30 -.22 -.02 .24 -.16 -.16 -.03

Nonglacial deposits -.13 .04 -.16 .20 .00 -.12 -.07 .13

Clay deposits -.02 .01 .12 .05 -.14 -.02 .09 -.07

Loam deposits .09 .02 .12 -.14 .18 -.07 .13 -.18

Peat deposits .05 .03 .18 .00 .06 -.11 .15 -.12

Sand deposits .12 -.04 .05 -.14 .04 .02 .03 -.02

Sand-and-gravel deposits .21 .19 .09 -.03 .11 -.01 .11 -.26

Physical-habitat characteristics

WIDTH 0.31 0.35 0.02 0.17 0.31 -0.28 0.54 -0.17

DEPTH .04 .15 .12 .32 .13 -.10 .25 -.21

THALD .08 .22 .12 .29 .18 -.15 .26 -.24

GRAD -.11 -.19 -.18 -.10 -.15 .04 -.16 .36

POOL% -.03 -.01 -.20 .03 -.05 .01 .07 .29

RIFF% .14 .00 -.17 -.07 -.01 -.11 .21 .26

RUN% -.03 .03 .24 .01 .07 .08 -.13 -.31

SEDEP -.13 .03 .12 -.01 .01 .07 -.30 -.29

SILT% -.40 -.32 .09 .18 -.39 .25 -.25 .20

SAND% .15 .27 -.05 -.15 .27 -.05 -.11 -.31

GRAV% .15 -.01 -.18 .03 .03 -.03 .39 .23

EMB% -.19 -.01 .11 -.04 -.03 .11 -.40 -.23

ALGAE% -.11 -.25 .00 .18 -.22 .05 .14 .33

MACR% -.07 .02 .08 -.04 -.03 -.02 -.10 .13

COVER% .11 .08 .12 .05 .07 .01 .02 -.10

SHADE% .01 .03 -.13 -.08 .02 .03 -.06 -.10

EROSION% -.11 -.06 -.16 .12 -.04 .03 .10 .01

BUFFER .07 .07 .12 -.08 .03 -.06 .07 -.23

Table 18. Spearman rank correlation coefficients (rs) between fish-community indices and median water-quality, environmental 

(anthropogenic/land-use, basin, soil, and surficial-deposit), and physical-habitat characteristics for the studied wadeable streams 

in Wisconsin—Continued. 

[all bold values were significant at p < 0.05, after being adjusted for the Bonferroni correction (Zar, 1999); see table 10 on page 49 for definitions of 

abbreviations and units for each parameter]

Fish Communities 75
SCHL, SD, and the anthropogenic/land-use characteristics 

than were the other indices. These fish indices were most 

strongly correlated with the percentage of total agriculture, 

row-crop agriculture, and forested areas. Better fish indices 

(high IBI, CARN%, and INTOL% values) occurred with 

lower percentages of agriculture and higher percentages 

of forest. INSECT%, TOL%, and FISHSPEC were less 

strongly correlated with most of the anthropogenic/landuse characteristics than were IBI, CARN%, and INTOL%. 

IBI, CARN%, OMNI%, and INTOL% were more strongly 

correlated with several basin characteristics (watershed 

area, air temperature, and runoff) and soil characteristics 

(clay content, erodibility, permeability, and soil slope) 

than were INSECT%, TOL%, and FISHSPEC. In general, 

streams with better fish indices have larger drainage areas, 

cooler air temperatures, higher runoff, and soils with lower 

clay content, lower erodibility, and higher permeability. 

These areas with better fish indices, again, are generally 

the mixed and mostly forested areas of Wisconsin (fig. 

2A).

In general, most fish indices were significantly correlated with only a few physical-habitat characteristics 

except for FISHSPEC and FISHN, which were significantly correlated with many of the characteristics. The 

physical-habitat characteristics most strongly correlated 

with fish indices were stream width and the percentage 

of silt in the bottom sediments. Better fish communities 

occurred in wider streams with lower percentages of silt 

in the sediments. More fish and more fish species were 

caught in streams with higher percentages of pools and 

riffles, gravel bottoms having less accumulated sediment 

(shallower sediment depths), lower percentages of rockysubstrate embeddedness, and a higher percentage of algal 

cover. More fish but fewer fish species were caught in narrower, shallower streams with steeper gradients. 

Responses to Changes in Nutrient 

Concentrations 

Responses of the three fish-community indices most 

strongly correlated with nutrient concentrations (IBI, 

CARN%, and INTOL%) are shown in figures 29 and 30. 

In general, IBI, CARN%, and INTOL% values decrease 

with increases in P and DP concentrations; however, no 

consistent pattern is apparent in the relations of these 

indices to changes in concentrations of the N constituents, 

except for NH4

-N. At low total P, DP, and NH4-N concentrations, the values of these fish indices ranged widely; 

however, at high nutrient concentrations, the values were 

generally indicative of poor water quality (low values). 

The upper bounds of the IBI, CARN%, and INTOL% plots 

may provide an indication of how P, DP, and NH4-N are 

capable of affecting the fish community. As was true for 

the other biotic indices, the variability below these bounds 

may be indicative of the effects of factors other than nutrients. 

Relations between selected fish indices and nutrient 

concentrations appear to be similar in the various EPZs 

and ecoregions (fig. 29). In all areas, there was a broad 

response at low nutrient concentrations and lower indices 

(generally indicative of poor water quality) at high nutrient (P, DP, and NH4

-N) concentrations. As for the other 

biotic indices, no significant differences in the responses 

were found among areas because of the range in the data, 

and because the gradient in nutrient concentrations within 

some areas was small.

Regression-tree analyses were done to define specific 

thresholds or breakpoints in the responses of the three 

fish-community indices that were most strongly correlated 

with the nutrient concentrations (table 19). The thresholds 

or breakpoints in the responses to changes in nutrient 

concentrations were consistent among these three indices. 

The thresholds in the responses to changes in P concentrations were about 0.06 mg/L, to changes in DP concentrations were from about 0.04 to 0.07 mg/L, and to changes 

in NH4-N concentrations thresholds were about 0.02–0.03 

mg/L. In general, below these thresholds the fish indices 

ranged widely, but were consistently poor above these 

thresholds. The regression-tree analyses defined specific 

thresholds for N, TKN, and NO3-N; however, the data in 

figures 29 and 30 do not indicate any change in the indices 

with changes in the concentrations of these constituents. 

Effects of Multiple Characteristics on Fish 

Indices

Stepwise Regressions

Forward stepwise regressions were done with the 

median water-quality, environmental, and physical-habitat 

characteristics to determine which four characteristics best 

described the variance in the fish indices (table 20). Models 

with more than four variables did not significantly increase 

the amount of variance explained. For most indices, either 

P or TKN concentration was the first variable incorporated 

in these models. If TKN concentrations were not included 

in these models, then P concentrations became the first 

variable in the models. Other important variables included 

the width and depth of the streams and characteristics 

describing the substrate of the stream bottom. As was 

76 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
0.055 mg/L 0.055 mg/L

0.055 mg/L 0.055 mg/L

0.539 mg/L0.539 mg/L

0.539 mg/L 0.067 mg/L

1.641 mg/L 1.641 mg/L 1.641 mg/L

1.641 mg/L 1.641 mg/L 1.641 mg/L

21.260 mg/L 21.260 mg/L 21.260 mg/L

21.260 mg/L 21.260 mg/L 21.260 mg/L 0.067 mg/L

0.539 mg/L0.539 mg/L

0.539 mg/L

Fish Index of Biotic Integrity Fish Index of Biotic Integrity Fish Index of Biotic Integrity Fish Index of Biotic Integrity

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IN MILLIGRAMS PER LITER

FISH INDEX OF BIOTIC INTEGRITY

Percentage of carnivorous fish

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Percentage of intolerant fish

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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IN MILLIGRAMS PER LITER

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EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTPDFANCHFNLFSWTPDFANCHFNLFSWTP

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

DFANCHFNLFSWTP

DFANCHFNLFSWTPDFANCHFNLFSWTP

Figure 29. Fish Index of Biotic Integrity values, the percentages of fish considered pollution intolerant, and the percentages of the fish that are carnivorous as a function of total 

phosphorus and total nitrogen concentration in the environmental phosphorus zones (EPZs) and level III ecoregions for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines. [DFA, Driftless Area; NCHF, North Central Hardwood Forests; NLF, Northern Lakes and Forests; and SWTP, Southeastern Wisconsin Till Plains]

Fish Communities 77
0.068 mg/L 3.455 mg/L

1.460 mg/L 1.460 mg/L 1.460 mg/L

20.550 mg/L 20.550 mg/L 20.550 mg/L

0.017 mg/L 0.408 mg/L

0.413 mg/L 0.018 mg/L 0.095 mg/L 0.041 mg/L

0.040 mg/L 4.693 mg/L 0.032 mg/L 0.413 mg/L

Fish Index of Biotic Integrity Fish Index of Biotic Integrity Fish Index of Biotic Integrity Fish Index of Biotic Integrity

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100

0.0 0.2 0.4 0.6 0.8 1.0

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

FISH INDEX OF BIOTIC INTEGRITY

0

870605040302010

0

90

100

0 5 10 15

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

0

870605040302010

0

90

0.0 0.1 0.2 0.3 0.4 0.5

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

0

870605040302010

0

90

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

870605040302010

0

90

100

0

87060

5040302010

0

90

100

0.0 0.5 1.0 1.5 2.0 2.5

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

MEDIAN DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

MEDIAN TOTAL KJELDAHL NITROGEN,

IN MILLIGRAMS PER LITER

Percentage of carnivorous fish

0.0 0.2 0.4 0.6 0.8 1.0

PERCENTAGE OF CARNIVOROUS FISH

Percentage of intolerant fish

0.0 0.2 0.4 0.6 0.8 1.0

PERCENTAGE OF INTOLERANT FISH

Percentage of carnivorous fish

0 5 10 15

Percentage of intolerant fish

0 5 10 15

Percentage of carnivorous fish

0.0 0.1 0.2 0.3 0.4 0.5

Percentage of intolerant fish

0.0 0.1 0.2 0.3 0.4 0.5

Percentage of carnivorous fish

0.0 0.5 1.0 1.5 2.0 2.5

Percentage of intolerant fish

0.0 0.5 1.0 1.5 2.0 2.5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

EPZ 1EPZ 2EPZ 3EPZ 4EPZ 5

Figure 30. Fish Index of Biotic Integrity values, the percentages of fish considered pollution intolerant, and the percentages of the fish that are carnivorous as a function of 

dissolved phosphorus, dissolved nitrite plus nitrate, dissolved ammonia, and total Kjeldahl nitrogen concentrations in the environmental phosphorus zones (EPZs) for the studied wadeable streams in Wisconsin. Computed thresholds in the response are identified by vertical lines.

78 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 19. Thresholds or breakpoints in the responses in fish indices to changes in nutrient concentrations for wadeable streams 

in Wisconsin. 

[all concentrations are in milligrams per liter] 

Biological Indices Total 

Phosphorus

Dissolved 

phosphorus

Total 

nitrogen

Dissolved nitrite 

plus nitrate

Dissolved 

ammonia

Total Kjeldahl 

nitrogen

Fish Index of Biotic 

Integrity (IBI)

0.055 0.068 0.539 3.455 0.017 0.408

Percentage of carnivorous 

fish (CARN%)

.055 .041 .539 .095 .018 .413

Percentage of intolerant 

fish (INTOL%)

.067 .040 .539 4.693 .032 .413

Table 20. Results of forward stepwise-regression analyses to explain variance in fish indices for the studied wadeable streams 

in Wisconsin.

[R2, coefficient of determination for the one-, two-, three-, and four-variable models; log, logarithm to base 10 transformation] 

Dependent variable First variable Second variable Third variable Fourth variable

Fish Index of Biotic Integrity 

(IBI)

Total phosphorus Stream width Percentage of silt Wetland (forested)

 Accumulative R2 0.14 0.21 0.25 0.27

Percentage of carnivorous fish 

(CARN%)

Kjeldahl nitrogen Nonglacial deposits Buffer width Runoff

 Accumulative R2 .23 .29 .31 .32

Percentage of insectivorous fish 

(INSECT%)

Kjeldahl nitrogen Percentage of pools Percentage of gravel Stream width

 Accumulative R2 .10 .16 .18 .22

Percentage of omnivorous fish 

(OMNI%)

Air temperature Stream depth Buffer width Point-source loading 

of phosphorus

 Accumulative R2 .15 .22 .27 .29

Percentage of tolerant fish 

(TOL%)

Kjeldahl nitrogen Stream width Flow per unit area Soil slope

 Accumulative R2 .15 .21 .23 .24

Percentage of intolerant fish 

(INTOL%)

Kjeldahl nitrogen Stream width Flow per unit area Soil slope

 Accumulative R2 .15 .26 .27 .29

Number of fish species 

(FISHSPEC)

Watershed area Percentage of gravel Kjeldahl nitrogen Buffer width

 Accumulative R2 .27 .35 .41 .42

Number of fish caught - log

(FISHN)

Erodibility Thalweg depth Percentage of stream 

shaded

Percentage of gravel

 Accumulative R2 .15 .23 .26 .30

Fish Communities 79
true for many other biotic-index models, even with four 

variables included, the relations only explained a small part 

of the total variance in these indices (in this case, from 22 

to 42 percent). The model that explained the most variance was for FISHSPEC, which had watershed area and 

bottom substrate as the first two variables incorporated in 

the model. 

Redundancy Analysis

Partial RDA was used to determine the relative importance of the nutrients, other water-quality characteristics, 

and environmental and physical-habitat characteristics 

(tables 2 and 10) in affecting the distribution of the fish 

communities (the eight fish indices). In this analysis, individual monthly (July and August) and median values were 

included for each nutrient constituent. A forward variableselection procedure, which correlated fish indices with the 

other factors, was used to select a subset of variables for 

each general type of characteristic. This procedure retained 

8 nutrient variables, 3 other water-quality characteristics, 

and 20 environmental and physical-habitat characteristics. 

These 31 characteristics explained 44 percent of the variance in the 8 fish-community indices. Of the explained 

variance, 15 percent was described by the nutrients alone, 

3 percent by the other water-quality characteristics alone, 

46 percent by the environmental and physical-habitat characteristics alone, and 36 percent by the interactions among 

all characteristics (fig. 31). About 56 percent of the total 

variance could not be explained with the characteristics 

examined in this study, and 16 percent of the total variance 

could not be separated into a single category of characteristics. 

Reference Values for the Fish Indices

Reference values for the three fish indices that were 

most related to nutrient concentrations (IBI, CARN%, 

and INTOL%) were determined by examining the index 

values at only the sites having both P and N concentrations at or below their respective reference concentrations. The median IBI value for the Reference sites was 

50 (with a 25th percentile of 40), the median reference 

CARN% value was 9.9 percent (with a 25th percentile of 

1.5 percent), and the median reference INTOL% value was 

14.7 percent (with a 25th percentile of 2.0 percent). Lower 

percentiles are given because larger values represent better 

fish communities. These median values were significantly 

higher than the median values measured at the High 

sites (35, 0.3 percent, and 2.0 percent respectively; fig. 

32). If 75 percent of the minimally impacted sites (the 

Reference sites) had index values at least as good as the 

reference condition, then the reference index values for 

IBI, CARN%, and INTOL% are 40, 9.9 percent, and 2.0 

percent, respectively. 

Comparing the median index values for the Reference 

sites with those for the Ref N and Ref P sites may provide 

an indication of whether P or N is more important in the 

degradation of the fish communities in streams with nutrient concentrations near reference conditions (fig. 32). For 

all three indices, there was no difference between median 

values for Reference sites and median values of the Ref 

N sites and Ref P sites. Therefore, small additions of P or 

N appear to have little effect on the fish communities in 

streams with nutrient concentrations near reference conditions. 

Nutrients

Other water-quality 

 characteristics

Environmental and 

 physical-habitat 

 characteristics

Interactions among

 categories

15% 3%

36%

46%

General categories

Figure 31. Percentages of explained variance in eight fish 

index values described by nutrients, other water-quality 

characteristics, environmental (anthropogenic/land-use, soil, 

and surficial-deposit characteristics) and physical-habitat 

characteristics, and interactions among categories (variance 

that can not be explained by a single category) for the studied 

wadeable streams in Wisconsin. [%, percentage of explained 

variance]

80 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Reference High Ref N Ref P

0

20

40

60

80

100

INDEX OF BIOTIC INTEGRITY

Reference High Ref N Ref P

0

20

40

60

80

100

PERCENTAGE OF INTOLERANT FISH

Reference High Ref N Ref P

0

20

40

60

80

100

PERCENTAGE OF CARNIVOROUS FISH

EXPLANATION

Outlier

Interquartile

range (IR)

75th percentile + 1.5 * IR

25th percentile – 1.5 * IR

75th percentile 

25th percentile 

Median

Figure 32. Fish Index of Biotic Integrity values, the percentages of the fish that are carnivorous, and the percentages of fish that 

are considered pollution intolerant in Reference sites, High (nonreference) sites, and sites with only reference total nitrogen (Ref 

N sites) or reference total phosphorus (Ref P sites) concentrations in the studied wadeable streams in Wisconsin.

Fish Communities 81
Multiparameter Biotic Indices to 

Estimate Nutrient Concentrations in 

Wadeable Streams

One goal of this study was to estimate nutrient concentrations in streams from the biotic data. Most of the 

biotic indices, however, had a wedge-shaped response to 

increases in nutrient concentrations. In other words, there 

was a broad response in almost all index values at low 

nutrient concentrations; however, at high nutrient concentrations, the indices had a narrow range of values normally 

indicative of poor conditions. This wedge-shaped response 

of the biotic indices to increases in nutrient concentrations 

is common in describing relations between biotic indices 

and human disturbance levels, such as the percentage of 

urban land use in an area (Wang and others, 2001; 2003). 

The wedge-shaped response implies that at low nutrient 

concentrations, factors other than nutrients are predominant factors limiting the health of biotic communities, 

whereas at high nutrient concentrations, nutrients may 

be the predominant factors affecting biotic communities 

(Cade and others, 1999). Although these relations between 

nutrient concentrations and biotic indices have rarely been 

reported for wadeable streams in the literature, relations 

similar to those found in this study have been reported 

between P concentrations and percentages of gastropods 

and predator macroinvertebrates in P-addition experiments 

in Everglades sloughs (King and Richardson, 2004). 

The wedge-shaped distribution makes predictions of 

low nutrient concentrations difficult with any single index. 

A combination of various biotic indices was used to assess 

whether this wedge-shaped response could be eliminated 

or at least reduced. To develop multiparameter indices to 

estimate P and N concentrations in wadeable streams, each 

of the indices found to be strongly related to changes in the 

nutrient concentrations was input into forward stepwiseregression analyses. Eleven biotic indices were included in 

this analysis: two describing chlorophyll a concentrations 

in the streams (log SCHL and log BCHL), three describing 

the periphytic-diatom community (DNI, DPTI, and DSI), 

three describing the macroinvertebrate community (HBI, 

EPTN%, and EPTTX%), and three describing the fish 

community (IBI, INTOL%, and CARN%). 

The four-parameter model to estimate P concentrations in wadeable streams included indices describing the 

diatom community (DSI and DNI), suspended chlorophyll 

a (SCHL), and the fish community (IBI), and explained 

54 percent of the variance in P concentrations (table 21). 

Models with more than four variables did not significantly 

increase the amount of variance explained (accumulative 

R2

 value). Measured and estimated log P concentrations 

are shown in figure 33A. This multiparameter model estimated high and low P concentrations equally well. 

The four-parameter model to estimate N concentrations included indices describing benthic chlorophyll a

(BCHL), the diatom community (DNI), the macroinvertebrate community (EPTTX%), and the fish community 

Table 21. Results of forward stepwise-regression analyses to explain variance in total phosphorus and total nitrogen 

concentrations with biotic indices in the studied wadeable streams in Wisconsin.

[log, logarithm to base 10 transformation; rs, Spearman correlation coefficient; R2, coefficient of determination for the one-, two-, three-, and four-variable models; SCHL, suspended chlorophyll a concentration; na, not applicable; all regressions were on log-transformed concentrations; see table 10 on 

page 49 for definitions of abbreviations and units for each parameter]

Statistical parameter Constant First variable Second variable Third variable Fourth variable

Total phosphorus (P)

Diatom DSI Log (SCHL) Diatom DNI Fish IBI

Coefficient in equation -1.797 0.005 0.300 0.140 -0.004

r

s na .60 .44 .47 -.33

Accumulative R2 na .32 .41 .48 .54

Total nitrogen (N)

Log (BCHL) EPTTX% Fish IBI Diatom DNI

Coefficient in equation -0.373 .200 -.007 -.005 .108

r

s na .49 -.39 -.31 .36

Accumulative R2 na .23 .33 .37 .41

82 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
y = 0.20x - 0.90

R2 = 0.41

y = 0.25x - 2.25

R2 = 0.54

y = 0.54x - 0.52

R2 = 0.54

y = 0.41x + 0.15

R2 = 0.41

ESTIMATED LOG (TOTAL NITROGEN,

IN MILLIGRAMS PER LITER)

MEASURED LOG (TOTAL NITROGEN,

IN MILLIGRAMS PER LITER)

-0.5-1.0

1.00.50.0

-1.0 -0.5 0.0 0.5 1.0 1.5

MEASURED LOG (TOTAL NITROGEN,

IN MILLIGRAMS PER LITER)

-0.5-1.0

1.51.00.50.0

0246 8 10

BIOTIC INDEX OF TOTAL NITROGEN (BIN)

-0.5-1.0-1.5-2.0

0.0

-2.0 -1.5 -1.0 -0.5 0.0 0.5

MEASURED LOG (TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER)

TOTAL PHOSPHORUS, ESTIMATED LOG (

IN MILLIGRAMS PER LITER)

MEASURED LOG (TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER) -0.5 -1.0 -1.5

-2.0-2.5

0.50.0

0246 8 10

BIOTIC INDEX OF TOTAL PHOSPHORUS (BIP)

A. B.C. D.

Figure 33. Measured and estimated 

A, total phosphorus and 

B, total nitrogen concentrations (logarithm to base 10 transformation) for the four-parameter regression models, 

C, measured phosphorus concentrations as a function of Biotic Index of total Phosphorus (BIP) values, and 

D, measured nitrogen concentrations as a function of Biotic Index of 

total Nitrogen (BIN) values, with the regression equations and coefficients of determination (R2) for the studied wadeable streams in Wisconsin. 

Multiparameter Biotic Indices to Estimate Nutrient Concentrations in Wadeable Streams 83
(IBI). This model explained 41 percent of the variance in 

N concentrations (table 21). Models with more than four 

variables did not significantly increase the amount of variance explained. Measured and estimated log N concentrations are shown in figure 33B. This multiparameter model 

estimated high and low N concentrations equally well, but 

did not estimate N concentrations as well as the P model 

estimated P concentrations.

The regression equations described in table 21 were 

then used to develop multiparameter biotic indices to 

estimate P and N concentrations in wadeable streams. The 

indices were developed to provide values ranging from 1 to 

10, with 1 representing the lowest P and N concentrations 

and 10 representing the highest concentrations. 

The Biotic Index of total P (BIP) is computed as:

 BIP = 4.0(-1.797 + 0.005DSI + 0.300Log SCHL + 

0.140DNI – 0.004IBI) + 9.0 (12) 

The Biotic Index of total N (BIN) is computed as:

 BIN = 5.0(-0.373 + 0.200LogBCHL – 0.007EPTTX% 

– 0.005 IBI + 0.108 DNI) + 4.5 (13)

The BIP and BIN values are plotted against their 

respective measured P and N concentrations in figures 33C 

and D. Both BIP and BIN estimate median P and N concentrations equally well over the range of concentrations 

measured in this study. The BIP predicted P concentrations 

better than the BIN predicted N concentrations (54 percent 

of the variance in P concentrations compared to 41 percent 

of the variance in N concentrations). The difference in the 

predictability of these indices was consistent with most of 

the biotic indices being more strongly correlated with P 

concentrations than with N concentrations. This difference 

in predictability suggests that P concentrations are more 

important than N concentrations in affecting the biotic 

communities over the range in nutrient concentrations 

measured in this study.

Summary and Conclusions

Excessive nutrient loss from watersheds is frequently 

associated with degraded water quality in streams. To 

reduce this loss from agricultural areas, performance standards and regulations for croplands and livestock operations are being proposed by various States. In addition, the 

USEPA is establishing regionally based nutrient criteria 

that can be refined by each State to determine whether 

actions are needed to improve a stream’s water quality. 

More confidence in the environmental benefits of the 

proposed standards and nutrient criteria are possible with 

a better understanding of the biotic responses to a range of 

nutrient concentrations in different environmental settings. 

To provide the information needed to guide the development of regionally based nutrient criteria for Wisconsin 

streams, the USGS and WDNR collected water-quality and biotic data in 240 wadeable streams throughout 

Wisconsin to: 1) describe how nutrient concentrations and 

biotic-community structure vary throughout the State; 2) 

determine which environmental characteristics are most 

strongly related to the distribution of nutrient concentrations; 3) determine reference water-quality and biotic 

conditions for different areas of the State; 4) determine 

how the biotic community of streams in different areas of 

the State respond to changes in nutrient concentrations; 5) 

determine the best regionalization scheme to describe the 

patterns in reference conditions and the responses in water 

quality and the biotic community; and 6) develop new 

indices to estimate nutrient concentrations in streams from 

a combination of biotic indices. 

Final Regionalization Scheme for Wisconsin 

Streams

Two regionalization schemes were proposed for 

defining nutrient criteria for Wisconsin’s wadeable 

streams: level III ecoregions and environmental phosphorus zones (EPZs). On the basis of the results of this study, 

the EPZ regionalization scheme was better than the level 

III ecoregion scheme at defining differences in reference 

water quality and differences in the responses in water 

quality to changes in land use for constituents that varied 

regionally. For some water-quality characteristics, however, the results indicated that little consistent variability 

was present and no regionalization was warranted. For 

total nitrogen (N) concentrations, suspended chlorophyll a

(SCHL) and Secchi tube depth (SD), the regional variabilities in reference conditions and in the water-quality 

responses are best described by subdividing wadeable 

streams into two categories: streams in areas with high 

clay-content soils (EPZ 3) and streams throughout the 

rest of the State (fig. 34). The regional variability in the 

response in total phosphorus (P) concentrations to changes 

in land use was also best described by subdividing the 

streams into these two categories; however, little consistent variability was found in reference P concentrations in 

streams throughout the State.

84 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Proposed regionalization scheme

for wadeable streams in Wisconsin

EXPLANATION

Areas without high 

clay-content soils

Areas with high 

clay-content soils

44°

45°

43°

46°

92°

91°

90°

89°

88°

87°

0

0 20 40 60 KILOMETERS

20 40 60 MILES

Figure 34. Proposed regionalization scheme for defining nutrient criteria for wadeable streams in Wisconsin.

Summary and Conclusions 85
Despite variation in nutrient concentrations among 

EPZs and level III ecoregions (especially lower nutrient concentrations in the northern part of the State), the 

responses of all of the biotic indices to changes in nutrient concentrations were similar throughout the State. In 

all areas, there was a broad response in the indices at low 

nutrient concentrations and a narrower range in values, 

indicative of poor water quality, at high nutrient concentrations. No regional differences were found in the biotic 

responses among areas; therefore, there is no reason to 

subdivide the streams based on the biotic response to 

changes in nutrient concentrations. 

Reference Conditions

Results of this study indicate that reference P concentrations for wadeable streams are similar throughout the 

State: 0.03–0.04 mg/L with an upper 95-percent confidence 

limit of 0.04–0.06 mg/L (table 22). These values are higher 

than those estimated by Robertson and others (2006), who 

estimated that reference P concentrations for Wisconsin 

streams and larger rivers were between 0.012 and 0.023 

mg/L. Values from this study are similar to those defined 

by the USEPA for nutrient ecoregion 7, but higher than 

those defined for nutrient ecoregion 8. The USEPA defined 

reference P concentrations for the DFA and SWTP ecoregions at 0.070 and 0.080 mg/L, respectively, which are 

higher than those estimated in this study. The higher values 

defined for the DFA and SWTP ecoregions were probably 

because most of the watersheds of streams in those areas 

are dominated by agriculture, and more than 25 percent of 

the streams are affected by anthropogenic factors.

Reference N concentrations can be subdivided into 

two categories: 0.6–0.7 mg/L with the upper 95-percent 

confidence limit of 0.7–1.0 mg/L in all streams except 

those in areas with high clay-content soils, where 0.4 mg/L 

and an upper 95-percent confidence limit of 0.6 mg/L are 

more appropriate (table 22). These values are also similar 

to those defined by the USEPA for nutrient ecoregion 7 

(0.54 mg/L), but higher than those defined for nutrient 

ecoregion 8 (0.20–0.38 mg/L). The USEPA defined reference N concentrations for the DFA and SWTP ecoregions 

to be 1.30–1.88 mg/L, which are higher than those estimated in this study, probably because most of the streams 

in these areas are dominated by agriculture.

 Reference SCHL concentrations can be subdivided 

into two categories: 1.2–1.7 μg/L with the upper 95-percent confidence limit of 1.7–2.2 μg/L in all streams except 

those in areas with high clay-content soils, where 1.0 μg/L 

and upper 95-percent confidence limit of 1.6 μg/L are 

more appropriate (table 22). These values are less than 

those defined by the USEPA for nutrient ecoregions 7 and 

8 when the trichromatic method of analysis is used (5.8 

and 4.3 μg/L, respectively). 

Reference water clarity can be subdivided into two 

categories: streams in areas with high clay-content soils 

(EPZ 3) with poorer reference water clarity (a SD of about 

110 cm), and streams throughout the rest of the State with 

better water clarity (SD greater than 115 cm; table 22). 

In all areas of the State, the upper 95-percent confidence 

limit for reference water clarity was better than could be 

measured with the 120-cm Secchi tube used in this study. 

It is likely that the poorer clarity in the streams in areas 

with high clay-content soils is caused by colloidal clay 

particles, which often remain in suspension. Reference 

SDs are not directly comparable with values defined by the 

USEPA for turbidity.

For each category of the biotic community (SCHL, 

BCHL, periphytic diatoms, macroinvertebrates, and fish), 

the indices most related to changes in nutrient concentrations are listed in table 22. The three diatom indices (Diatom Nutrient Index (DNI), Diatom Siltation Index (DSI), 

and Diatom Biotic Index (DBI)) displayed the strongest 

responses to changes in nutrient concentrations. The three 

macroinvertebrate indices that displayed the strongest 

responses to changes in nutrient concentrations were the 

Hilsenhoff Biotic Index (HBI), the percentage of individuals that were Ephemeroptera, Plecoptera, or Trichoptera 

(EPTN%), and the percentage of taxa that were Ephemeroptera, Plecoptera, or Trichoptera (EPTTX%). The 

three fish indices that displayed the strongest responses to 

changes in nutrient concentrations were the fish Index of 

Biotic Integrity (IBI), the percentage of carnivorous fish 

(CARN%), and the percentage of fish that are considered 

pollution intolerant (INTOL%). Values of each of these 

indices ranged widely when nutrient concentrations were 

at or below the reference concentrations, but were significantly different from the respective values for streams with 

nutrient concentrations significantly higher than reference 

conditions. The median values of the biotic indices at the 

Reference sites (sites with nutrient concentrations at or 

below reference concentrations) are given in table 22. It 

has been suggested that the upper 75th percentile for the 

concentration data for a subset of streams thought to be 

minimally impacted for a defined area may represent the 

reference conditions. This upper 75th percentile assumes 

that high values are indicative of poor conditions. For 

some biotic indices, however, lower values are indicative 

of poor conditions; therefore, the values for each biotic 

index at the worst 75th percentile of the subset of streams 

86 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Table 22. Reference conditions for water quality, chlorophyll a, diatoms, macroinvertebrates, and fish indices for wadeable 

streams in Wisconsin.

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; %, percent; mg/L, milligram per liter; μg/L, microgram per liter; cm, centimeter; >, greater than; 

mg/m2, milligram per square meter]

Median reference Upper 95-percent confidence limits

Total phosphorus (P) (mg/L)

 Entire State 0.03–0.04 0.04–0.06

Total nitrogen (N) (mg/L)

 High-clay content areas (EPZ 3) 0.4 0.6

 Rest of State 0.6–0.7 0.7–1.0

Suspended chlorophyll a (SCHL)(μg/L)

 High-clay content areas (EPZ 3) 1.0 1.6

 Rest of State 1.2–1.7 1.7–2.2

Secchi tube depth (SD)(cm)

 High-clay content areas (EPZ 3) 110 > 120

 Rest of State >115 > 120

Median reference 1Worst 75th percentile of sites with 

reference nutrient concentrations

Benthic Chlorophyll a (BCHL)(mg/m2

) 331 673

Diatoms

 Diatom nutrient index (DNI) 3.4 4.1

 Diatom siltation index (DSI) 11.8 22.5

 Diaton biotic index (DBI) 47.5 37.4

Macroinvertebrates

 Hilsenhoff Biotic Index (HBI) 3.1 4.4

 Percentage of EPT individuals (EPTN%) 59.7 50.7

 Percentage of EPT taxa (EPTTX%) 50.0 38.0

Fish

 Fish Index of Biotic Integrity (IBI) 50.0 40.0

 Percentage of carnivorous fish (CARN%) 9.9 1.5

 Percentage of intolerant fish (INTOL%) 14.7 2.0

1 Lower values of the indices are not always indicative of better biotic conditions; therefore, the values at the worst (or poorer) 75th percentiles of a 

subset of minimally impacted streams are given.

Summary and Conclusions 87
thought to be minimally impacted would represent the reference condition. The values of each of the biotic indices 

at the worst 75th percentile for the minimally impacted 

streams are given in table 22.

Responses of Water Quality to Changes in 

Land Use 

Concentrations of P and N in streams throughout the 

State increase at different rates as the percentage of agricultural land increases. Concentrations of P increase more 

quickly and concentrations of N increase more slowly in 

response to increasing percentages of agriculture in areas 

with high clay-content soils than do P and N concentrations in streams in the rest of the State. The response 

of water clarity to changes in nutrient concentrations is 

similar in streams throughout the State. The streams in 

areas with high clay-content soils, however, have a lower 

reference water clarity, and their clarity remains lower 

than that in streams from other areas with similar nutrient 

concentrations as the percentage of agriculture increases. 

Responses of Biotic Indices to Changes in 

Nutrient Concentrations

The responses of biotic indices to changes in nutrient 

concentrations were examined when nutrient concentrations were at or near reference concentrations and thus had 

potential to limit biotic growth, and as nutrient concentrations increase. Comparison of the median index values for 

Reference sites with those for sites with P concentrations 

at or below reference conditions, but with N concentrations 

above reference conditions and with those of sites with N 

concentrations at or below the reference conditions, but 

with P concentrations above reference conditions provided 

an indication of whether P or N was more important in 

affecting the biota. For SCHL, P was the more important 

limiting nutrient, whereas for BCHL and all of the macroinvertebrate indices, N was the more important limiting 

nutrient. For other diatom indices and all fish indices, there 

were no differences between the median values for Reference sites and those of the other two categories of sites; 

therefore, small additions of P or N appear to have little 

effect on these communities in streams with nutrient concentrations near reference conditions. At the start of this 

study, it was thought that the biota in streams were more 

affected by P than N concentrations; however, these results 

suggest that in streams with low nutrient concentrations, 

N may be at least as important as P in affecting BCHL 

concentrations and the macroinvertebrate communities.

Changes in the biotic indices as nutrient concentrations increase indicate that nutrients have direct or indirect 

effects on the composition of the biotic community in 

Wisconsin’s wadeable streams. Visual inspection of scatterplots and results of Spearman correlations and multiple 

linear regressions indicate that as nutrient concentrations 

increase above reference conditions, changes in the biotic 

community are more strongly related to changes in P 

concentrations than to changes in N concentrations. The 

relations between nutrient concentrations and most biotic 

indices were found to be nonlinear. The biotic integrity of 

wadeable streams was negatively correlated with increasing nutrient concentrations, and the effects on the biotic 

community were largest at relatively low nutrient concentrations. From the data collected in this study, nutrient-concentration thresholds were identified where a small change 

in nutrient concentrations corresponds to a relatively 

large change in the biotic communities. A summary of 

the nutrient thresholds is given in table 23. The thresholds 

in the responses to changes in P concentrations ranged 

from 0.039 mg/L for BCHL, to about 0.06–0.07 mg/L for 

SCHL, diatom indices, and fish indices, to about 0.09–0.10 

mg/L for macroinvertebrate indices and SD. The thresholds in the responses to changes in N constituents were 

more variable than for P concentrations. The thresholds in 

the responses to changes in N concentrations ranged from 

about 0.5–0.6 mg/L for the fish indices and one macroinvertebrate index, to about 0.9–1.2 for SCHL, the diatom 

indices, and the other macroinvertebrate indices, to about 

3.3 mg/L for SD. The thresholds for most of the biotic 

responses were not much above the reference concentrations estimated for P and N throughout the State. 

Most of the biotic indices had a wedge-shaped 

response to increases in nutrient concentrations. In other 

words, there was a broad response in almost all index 

values at low nutrient concentrations; however, at high 

nutrient concentrations, the indices had a narrow range of 

values normally indicative of poor water-quality conditions. This wedge-shaped response of the biotic indices to 

increases in nutrient concentrations is common in describing relations between biotic indices and human disturbance 

levels. The wedge-shaped response implies that at low 

nutrient concentrations, factors other than nutrients are 

predominant factors limiting the health of biotic communities, whereas at high nutrient concentrations, nutrients may 

be the predominant factors affecting biotic communities. 

88 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
Although there were significant correlations and 

visual relations between the nutrient concentrations and the 

characteristics of biotic communities, this may or may not 

be an indication of cause-and-effect relations. The biotic 

communities that are present in a stream reflect the overall 

ecological integrity (in other words, physical, chemical, 

and biological integrity); therefore, they integrate the 

effects of many different stressors (such as hydrology, 

sedimentation, pesticides, and nutrients) over the timespan of days to years and thus provide a broad measure of 

their aggregate impact. In addition, the geomorphology, 

geochemistry, land use, and land cover in the watershed 

control the physical/chemical habitat of the stream where 

the biota live. The characteristics of biotic communities 

are controlled by many environmental factors, though they 

may be directly affected by only a subset of variables. 

Results of redundancy analyses indicate that nutrients 

alone explained only a small part of the variance in the 

biotic indices for wadeable streams, and about a third of 

the variance could not be resolved into single categories 

of environmental characteristics. Nutrient concentrations 

by themselves explained from about 6 to 13 percent of 

the total variance in the biotic indices or about 13 to 23 

percent of the explained variance. Nutrient concentrations 

were most important in affecting SCHL concentrations 

and macroinvertebrate communities, and least important 

in affecting BCHL concentrations, periphytic diatoms, and 

fish communities. 

Multiparameter Biotic Indices to Estimate 

Nutrient Concentrations in Wadeable 

Streams

One goal of this study was to develop an index based 

on biotic indices to estimate nutrient concentrations in 

streams. Most of the biotic indices had wedge-shaped 

responses to increases in nutrient concentrations; thus, 

estimations of low nutrient concentrations would be difficult with any single index. Through the use of a combination of the biotic indices that were significantly correlated 

to nutrient concentrations, two new multiparameter indices 

were developed which eliminated this nonlinear response 

(Biotic Index of total Phosphorus, BIP, and Biotic Index of 

total Nitrogen, BIN). These multiparameter models estiTable 23. Summary of thresholds or breakpoints in the responses of suspended chlorophyll a concentrations, Secchi tube depth, 

and various biotic indices to changes in nutrient concentrations for wadeable streams in Wisconsin.

[EPT, Ephemeroptera, Plecoptera, and Trichoptera; all concentrations are in milligrams per liter]

Indices Total 

phosphorus

Dissolved 

phosphorus

Total 

nitrogen

Dissolved nitrite 

plus nitrate

Dissolved 

ammonia

Total Kjeldahl 

nitrogen

Water quality

Suspended chlorophyll a (SCHL) 0.070 0.028 1.169 0.095 0.057 0.563

Secchi tube depth (SD) .106 .047 3.305 2.583 .039 .920

Benthic chlorophyll a and diatom indices

Benthic chlorophyll a (BCHL) .039 .020 .918 .187 .040 .310

Diatom Nutrient Index (DNI) .057 .026 1.216 .381 .021 .745

Diatom Siltation Index (DSI) .074 .046 .872 .089 .022 1.080

Diatom Biotic Index (DBI) .072 .039 1.169 .381 .022 .388

Macroinvertebrate indices

Hilsenhoff Biotic Index (HBI) .088 .077 .609 3.455 .029 .965

Percentage of EPT individuals (EPTN%) .087 .077 .970 1.157 .029 1.053

Percentage of EPT taxa (EPTTX%) .091 .061 1.106 3.585 .034 .938

Fish indices

Fish Index of Biotic Integrity (IBI) .055 .068 .539 3.455 .017 .408

Percentage of carnivorous fish (CARN%) .055 .041 .539 .095 .018 .413

Percentage of intolerant fish (INTOL%) .067 .040 .539 4.693 .032 .413

Summary and Conclusions 89
mated high and low nutrient concentrations equally well. 

The BIP estimated P concentrations better than the BIN 

estimated N concentrations (54 percent of the variance in 

P concentrations compared to 41 percent of the variance in 

N concentrations). The difference in the predictability of 

these indices was consistent with the biotic indices being 

more strongly correlated to P concentrations than to N 

concentrations. This difference again suggests that P concentrations are more important than N concentrations in 

affecting the biotic communities as nutrient concentrations 

increase above reference conditions.

Nutrient Concentrations Controlling the 

Biotic Integrity of Streams

Rather than examining causal relations between nutrients and the biotic community structure, this study focused 

on demonstrating that nutrient concentrations are correlated with the health of wadeable streams, that specific 

responses exist and in some cases differ geographically, 

and that specific nutrients are more related to changes 

in stream health than other nutrients. With the results of 

this study, management activities can be better directed to 

reduce the controllable nutrient sources. Although the specific mechanisms of how nutrients affect the biota in wadeable streams were not examined, the results of this study 

indicate that nutrients are important in controlling the 

biotic health of streams. The biotic-community structure 

represents the overall ecological integrity of the stream; 

however, results of this study demonstrated that nutrients 

alone explained only a small part of the variability in the 

structure. Therefore, it is difficult to predict the exact result 

of reducing nutrient concentrations without also modifying the factors typically associated with high nutrient 

concentrations. Nutrient concentrations in many streams, 

especially those in agricultural areas, are well above the 

response thresholds for the biotic indices; therefore, small 

reductions in concentrations in these streams are not 

expected to have large effects on the biotic community. 

Even with these limitations, however, it is expected that 

reducing nutrient concentrations will improve the biotic 

community, further the beneficial ecological uses of most 

streams, and improve the quality of downstream nutrientlimited receiving waters. 

90 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin
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Appendixes
96 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

1 Onion 04026232 NLF-18 3 90.8903 46.7547 2001 15.4 0.0171

2 Thompson 040263165 NLF-15 3 90.9161 46.6686 2001 13.3 .0055

3 Parker 04027788 NLF-12 3 90.4358 46.5608 2001 8.4 .0027

4 Catlin 053315805 NLF-03 1 91.7911 46.3975 2001 5.2 .0111

5 Leo 05331581 NLF-14 1 91.8214 46.3222 2001 15.3 .0078

6 Lower Ox 05331590 NLF-10 1 91.7381 46.3222 2001 221.7 .0026

7 Lord 05331615 NLF-29 1 91.9089 46.2756 2001 26.5 .0068

8 Fivemile 05331811 NLF-01 1 91.2158 46.2042 2001 3.2 .0206

9 Cap 05331813 NLF-33 1 91.2344 46.1975 2001 39.7 .0032

10 Spring Cr 05331814 NLF-22 1 91.2417 46.1986 2001 13.8 .0055

11 Mosquito Br 05331856 NLF-35 1 91.3947 46.0458 2001 24.3 .0032

12 Smith Lake 053318635 NLF-24 1 91.4883 46.0450 2001 19.6 .0033

13 Fiddler 05331872 NLF-02 1 91.5139 45.9936 2001 8.2 .0098

14 Spring Lake 05331873 NLF-23 1 91.4831 45.9911 2001 16.6 .0066

15 Rainbow 05331877 NLF-19 1 91.5192 45.9608 2001 2.9 .0180

16 Dody Brook 05335530 NLF-20 2 92.5036 45.9186 2001 23.9 .0019

17 Swan 05356324 NLF-04 2 91.2369 45.6678 2001 25.1 .0104

18 Becky 05356368 NLF-06 1 91.3108 45.5522 2001 9.5 .0127

19 Hay 053563725 NLF-30 1 91.3178 45.4647 2001 24.8 .0162

20 Soft Maple 05356700 NLF-09 1 91.3507 45.4178 2001 82.7 .0180

21 Mcdermott 05356729 NLF-28 1 91.4408 45.3386 2001 21.0 .0138

22 Meadow Cr 05361730 NLF-41 2 90.6183 45.4500 2001 5.4 .0157

23 Gilbert Cr 05361833 NLF-40 2 90.6583 45.4586 2001 10.3 .0162

24 Trib 1 Shoulder Cr 05362010 NLF-44 2 90.8222 45.3186 2001 7.3 .0057

25 Crazy Horse Cr 05362325 NLF-39 2 90.7192 45.4336 2001 5.8 .0007

26 Alder Cr 05362409 NLF-38 2 90.7197 45.4133 2001 4.5 .0299

27 Sailor Cr 05363619 NLF-43 2 90.5586 45.2725 2001 9.4 .0069

28 Knuteson 05367087 NLF-34 2 91.4814 45.7094 2001 71.4 .0153

29 South Fork Hemlock 05367182 NLF-08 2 91.4756 45.5678 2001 9.0 .0267

30 Little Soft Maple 05376697 NLF-27 1 91.3789 45.4486 2001 21.9 .0161

31 Alvin 04059789 NLF-16 2 88.8739 45.9689 2001 14.4 .0075

32 North Otter 04067725 NLF-07 2 88.8094 45.5889 2001 7.4 .0070

33 North Fork Thunder 04068090 NLF-36 1 88.3550 45.3431 2001 35.2 .0053

34 Waupee 04070175 NLF-25 1 88.3711 45.2242 2001 31.7 .0050

35 Trout 04072167 NCHF-19 2 88.1517 44.5383 2001 35.7 .0055

36 South Fork Popple 053808864 NCHF-17 2 90.3753 44.8000 2001 23.3 .0023
Appendixes 97

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.037 0.028 0.151 0.081 0.010 0.070 0.768 9.3 139.0 >120.0 7.8 10.0

.052 .040 .244 .092 .007 .120 1.138 11.1 246.0 >120.0 8.2 15.0

.018 .013 .486 .018 .013 .450 1.255 15.7 320.5 >120.0 8.0 50.0

.024 .016 .452 .081 .025 .405 .412 15.0 161.5 >120.0 7.6 80.0

.021 .010 .398 .017 .014 .375 .708 16.2 89.0 >120.0 7.2 110.0

.027 .011 .330 .005 .007 .320 2.135 20.1 116.5 >120.0 8.1 40.0

.033 .019 .808 .005 .028 .715 .870 16.8 106.0 106.0 7.4 141.0

.029 .015 .900 .022 .019 .870 .798 15.9 136.5 >120.0 7.1 141.0

.039 .018 .689 .027 .021 .660 2.241 16.0 105.5 >120.0 6.9 141.0

.025 .010 .455 .011 .007 .440 1.340 17.3 135.5 >120.0 7.2 90.0

.021 .011 .403 .018 .017 .360 .580 16.5 129.5 >120.0 7.4 45.0

.092 .069 .759 .012 .039 .725 2.373 19.1 121.5 >120.0 6.8 60.0

.036 .017 .454 .074 .026 .380 2.568 16.3 194.0 >120.0 7.7 50.0

.048 .022 .592 .021 .057 .560 1.811 16.9 144.5 119.0 7.0 80.0

.032 .010 .200 .005 .017 .190 1.585 13.1 200.5 >120.0 7.6 15.0

.038 .020 .422 .032 .021 .390 1.507 14.0 161.0 >120.0 7.2 110.0

.051 .035 .758 .357 .019 .420 1.555 15.7 133.0 >120.0 7.2 80.0

.038 .032 .416 .091 .015 .320 .822 13.9 50.0 >120.0 7.7 90.0

.111 .085 .620 .020 .018 .600 1.951 15.5 89.5 >120.0 6.5 110.0

.114 .066 .735 .181 .027 .595 4.418 15.7 148.0 69.6 7.7 90.0

.139 .084 .626 .025 .038 .595 2.080 15.7 207.5 >120.0 7.4 110.0

.160 .124 1.435 .014 .029 1.430 2.260 15.6 142.0 112.0 7.0 140.0

.103 .064 1.127 .012 .042 1.100 3.060 14.8 120.0 >120.0 7.0 140.0

.101 .065 1.158 .028 .030 1.130 1.560 14.7 117.5 >120.0 6.5 130.0

.102 .065 1.390 .017 .047 1.380 2.705 14.3 65.0 86.0 6.8 141.0

.093 .069 1.230 .016 .040 1.210 2.689 14.3 73.5 85.5 6.8 120.0

.069 .052 .868 .032 .033 .780 1.027 14.7 86.5 >120.0 7.3 140.0

.044 .023 .511 .053 .026 .475 4.460 17.3 113.5 >120.0 7.9 4.3

.074 .060 .536 .041 .021 .465 1.184 14.1 100.5 >120.0 7.5 80.0

.068 .041 .709 .015 .024 .690 1.753 14.2 55.5 >120.0 7.4 100.0

.020 .012 .492 .027 .015 .450 .903 12.9 142.0 >120.0 7.5 141.0

.027 .016 .363 .034 .021 .315 1.875 16.1 247.0 >120.0 7.9 141.0

.014 .008 .326 .075 .007 .245 .504 10.7 238.0 >120.0 8.0 80.0

.017 .008 .625 .025 .026 .600 1.410 17.1 220.0 >120.0 8.0 65.0

.178 .125 3.020 1.885 .058 .955 .797 15.2 802.0 >120.0 8.1 120.0

.172 .125 1.655 0.005 .038 1.650 2.626 16.3 156.5 >120.0 6.8 141.0
98 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

37 Mosquito Cr 05390240 NLF-26 1 89.0758 45.8378 2001 26.7 .0066

38 Hay Meadow 05390248 NLF-17 1 89.0458 45.8683 2001 16.8 .0077

39 Cedar Springs 05391045 NLF-37 1 89.5231 45.7247 2001 2.2 .0548

40 Skunk Cr 05391068 NLF-21 1 89.4589 45.7075 2001 15.0 .0112

41 Jennie 05392002 NLF-05 1 89.5614 45.5631 2001 4.4 .0289

42 Trout 05392006 NLF-11 1 89.5925 45.5497 2001 13.6 .0018

43 Muskellunge – 

Heafford Junction

05392030 NLF-42 1 89.6972 45.5108 2001 16.3 .0125

45 Johnson 05392109 NLF-31 1 89.7358 45.8997 2001 27.8 .0053

46 Threemile 05392227 NLF-13 1 89.7728 45.8158 2001 13.1 .0005

47 Raeder Cr 05399348 NCHF-13 2 90.2350 44.8511 2001 8.3 .0182

48 Hamann Cr 05399415 NCHF-09 4 90.1119 44.9308 2001 11.9 .0119

49 East Fork Hamann 05399420 NCHF-04 4 90.0786 44.9317 2001 7.9 .0063

50 Hamann Trib 05399434 NCHF-22 4 90.1117 44.9019 2001 6.3 .0061

51 Widow Green 04072670 NCHF-24 2 89.6175 43.7308 2001 8.7 .0055

52 North Fork Willow 05341629 NCHF-11 1 92.2189 45.2344 2001 26.4 .0019

53 Black Brook 05341676 NCHF-02 1 92.3417 45.1833 2001 37.6 .0028

54 South Fork Willow 053416925 NCHF-16 1 92.3531 45.1275 2001 26.1 .0059

55 Hutton Cr 053416927 NCHF-10 1 92.3561 45.1217 2001 51.3 .0021

56 Tenmile Cr 05341732 NCHF-18 1 92.6094 45.0500 2001 47.2 .0091

57 Cr 12–13 05366709 NCHF-06 1 91.6611 45.0067 2001 12.5 .0131

58 Running Valley 05367506 NCHF-14 1 91.6614 45.0267 2001 13.4 .0076

59 Cr 1–8 05367507 NCHF-08 1 91.6686 45.0261 2001 5.8 .0013

60 Cr 1–12 05367508 NCHF-05 1 91.6503 45.0189 2001 6.4 .0066

61 18-mile 05367515 NCHF-07 1 90.1219 44.3022 2001 55.6 .0098

62 Cady 05370509 DFA-08 4 92.1761 44.8414 2001 31.9 .0038

63 Eagle 05378181 DFA-12 4 91.6789 44.2197 2001 17.7 .0077

64 Joos 05378183 DFA-11 4 91.6647 44.2147 2001 15.5 .0074

65 Trout Run 05379430 DFA-13 4 91.5683 44.2136 2001 19.6 .0068

66 Bohris 05379472 DFA-14 4 91.5972 44.1456 2001 24.5 .0061

67 South Branch Oneill Cr 05380984 NCHF-15 2 90.3761 44.6031 2001 15.3 .0110

68 Unnamed Trib 1 East 

Fork Black

053811665 NCHF-21 2 90.4928 44.4075 2001 13.9 .0064

69 Unnamed Trib 1 

Rock Cr

05381168 NCHF-23 2 90.4942 44.4661 2001 9.0 .0069

70 Bloody Run 05400881 NCHF-03 1 89.7853 44.3425 2001 17.7 .0043

71 Beaver Cr 05401764 NCHF-01 2 90.1814 44.5983 2001 11.1 .1215
Appendixes 99

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.030 0.016 0.837 0.019 0.036 0.825 1.545 14.6 53.0 102.0 6.9 141.0

.027 .013 .741 .005 .020 .735 2.775 17.3 67.0 >120.0 7.1 141.0

.032 .022 1.075 .018 .033 1.070 .848 14.6 65.0 >120.0 7.2 --

.040 .019 .950 .009 .036 .930 1.935 16.0 44.0 66.0 6.8 141.0

.039 .019 .467 .036 .047 .375 2.990 15.2 120.0 >120.0 7.0 80.0

.041 .026 .500 .076 .025 .410 1.623 11.5 88.0 >120.0 6.8 141.0

.029 .013 .542 .102 .037 .415 3.216 14.8 112.0 >120.0 7.5 141.0

.019 .004 .486 .031 .026 .450 3.045 18.2 159.0 >120.0 8.5 15.0

.038 .021 .619 .011 .034 .610 3.353 17.7 82.0 >120.0 7.2 100.0

.188 .140 3.010 2.020 .030 .840 3.383 15.2 271.5 85.0 7.0 141.0

.094 .068 2.165 1.056 .020 .740 1.212 14.5 300.0 >120.0 7.0 120.0

.178 .121 .990 .052 .035 .945 3.333 15.8 329.0 >120.0 7.7 110.0

.112 .087 2.675 1.845 .036 .805 3.887 15.2 340.5 >120.0 7.2 110.0

.041 .026 .773 .508 .018 .295 1.536 13.8 385.5 >120.0 8.1 30.0

.132 .071 .831 .046 .024 .785 5.780 18.2 152.5 66.0 7.6 110.0

.134 .077 1.246 .164 .054 .810 1.437 17.5 218.5 >120.0 7.7 140.0

.177 .095 1.644 .819 .035 .545 1.535 15.7 342.5 >120.0 7.7 55.0

.092 .064 4.005 3.400 .030 .540 1.725 14.8 399.5 >120.0 8.0 110.0

.065 .043 4.870 4.355 .025 .515 1.674 14.3 427.0 >120.0 7.9 55.0

.234 .208 3.080 2.550 .023 .410 .594 11.7 129.5 >120.0 6.7 15.0

.203 .129 1.114 .226 .037 .540 .744 13.4 160.0 >120.0 6.7 110.0

.246 .193 5.280 4.610 .049 .440 .404 12.0 176.5 >120.0 6.6 25.0

.527 .385 2.640 1.995 .057 .590 .602 12.6 188.0 106.0 7.0 30.0

.295 .259 2.620 1.975 .023 .455 .816 12.6 138.0 >120.0 7.0 30.0

.032 .025 3.290 3.170 .010 .135 1.811 11.6 483.0 >120.0 7.9 5.0

.056 .047 1.605 1.335 .041 .330 2.097 15.4 540.5 102.0 8.3 10.0

.068 .038 1.458 1.105 .049 .410 2.992 17.0 538.0 89.0 8.3 10.0

.196 .083 1.489 1.005 .061 .510 1.297 13.7 579.0 67.5 8.0 15.0

.141 .072 1.100 .730 .044 .365 2.028 13.7 534.0 67.5 8.1 5.0

.196 .133 1.724 .121 .059 1.400 5.595 17.4 185.0 87.5 8.7 141.0

.023 .011 .698 .013 .021 .685 2.324 16.7 27.0 115.0 7.0 141.0

.132 .069 1.629 .059 .090 1.550 5.520 17.2 63.5 37.5 6.8 141.0

.027 .013 1.690 1.430 .028 .265 .685 13.2 174.0 >120.0 7.4 140.0

.149 .109 1.304 .129 .064 1.100 2.640 15.2 418.0 >120.0 7.4 141.0
100 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

72 Trib To Beaver Cr 054017645 NCHF-20 2 90.1675 44.5981 2001 12.4 0.1017

73 North Fork 

Hemlock Cr

05402040 NCHF-12 2 90.0281 44.5697 2001 12.5 .0056

74 Mormon 05386295 DFA-46 4 91.0697 43.7531 2001 28.2 .0048

75 Timber Coulee 05386479 DFA-07 4 90.9039 43.7233 2001 31.2 .0083

76 Spring Coulee 05386493 DFA-43 4 90.9700 43.7078 2001 29.4 .0089

77 Rush-02 05388368 DFA-36 4 91.0231 43.4197 2001 34.2 .0049

78 Beaver 054040135 DFA-03 4 90.3594 43.6261 2001 12.6 .0041

79 Dilly 05404112 DFA-05 4 90.3958 43.6531 2001 12.1 .0076

80 Trib West Branch 

Baraboo

054041125 DFA-01 4 90.4025 43.6603 2001 10.5 .0119

81 Crooked 05407190 DFA-40 4 90.6964 43.0919 2001 28.9 .0110

82 Moore 05407410 DFA-09 4 90.6181 43.8303 2001 47.0 .0056

83 Warner Br 05407740 DFA-02 4 90.4967 43.6147 2001 4.9 .0070

84 Warner 05407775 DFA-04 4 90.4942 43.6433 2001 10.2 .0388

85 Otter Cr – Lafarge 05408149 DFA-38 4 90.6725 43.5853 2001 21.8 .0103

86 Harrison 05409090 DFA-41 4 90.7689 43.4978 2001 18.0 .0085

87 Mccartney Br 05412709 DFA-21 5 90.9161 42.7164 2001 6.2 .0040

88 Hackett Br 05413268 DFA-19 4 90.8822 42.8311 2001 12.4 .0076

89 Kuenster 054134435 DFA-27 5 90.9572 42.7908 2001 23.6 .0130

90 Muskellunge Cr – 

Beetown

05413447 DFA-25 4 90.9358 42.7939 2001 18.1 .0060

91 Bull 05413885 DFA-28 4 90.5889 42.8467 2001 29.2 .0071

92 Willow 05413959 DFA-10 4 90.5964 42.7942 2001 17.5 .0096

93 Mounds Br 05414129 DFA-18 4 90.3889 42.7914 2001 7.3 .0099

94 Young Br 05414205 DFA-20 4 90.5322 42.7619 2001 6.1 .0019

95 Mcadam Br 05414259 DFA-22 4 90.5189 42.6247 2001 9.5 .0075

96 Indian Cr – Dickeyville 05414278 DFA-16 5 90.6322 42.6183 2001 9.4 .0052

97 Kieler Cr 05414753 DFA-23 5 90.5967 42.5814 2001 8.4 .0031

98 Apple 05418731 DFA-26 4 90.1339 42.5228 2001 24.2 .0187

99 Trib 1 French 

Spring Cr

040727260 SWTP-09 1 89.3103 43.5917 2001 2.9 .0100

100 Rowan 05405598 SWTP-48 4 89.3861 43.3864 2001 27.4 .0087

101 Hinkson 05405648 SWTP-47 1 89.4111 43.4172 2001 13.0 .0066

102 North Branch Honey 05406210 DFA-44 4 89.9692 43.3514 2001 34.0 .0050

103 Moen 05406370 DFA-29 4 89.7578 43.0347 2001 6.1 .0118

104 Trout Cr – Barneveld 05406573 DFA-06 4 89.9467 43.0478 2001 21.7 .0096

105 Lowery 05406602 DFA-30 4 90.0525 43.1036 2001 10.0 .0045
Appendixes 101

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.179 0.122 1.178 0.163 0.052 1.000 2.560 15.3 241.0 115.0 7.2 120.0

.304 .243 1.505 .038 .055 1.500 3.860 15.9 222.0 100.0 7.3 110.0

.045 .032 1.415 1.255 .014 .175 2.318 12.4 520.5 >120.0 8.4 10.0

.046 .029 2.105 1.890 .012 .255 3.518 13.1 470.5 >120.0 8.5 10.0

.039 .027 1.885 1.770 .016 .210 2.191 12.9 483.0 >120.0 8.4 5.0

.040 .035 2.615 2.435 .011 .195 1.780 13.5 464.0 >120.0 8.2 5.0

.106 .074 1.975 1.440 .027 .480 2.731 14.7 414.0 >120.0 8.1 15.0

.087 .044 1.565 1.150 .032 .380 3.248 13.6 425.0 76.5 8.1 15.0

.052 .029 2.055 1.720 .020 .335 1.451 12.5 516.0 >120.0 8.0 15.0

.044 .033 2.510 2.435 .014 .075 1.605 11.4 559.0 >120.0 7.4 5.0

.093 .056 1.223 .798 .023 .455 2.333 15.6 416.0 115.0 7.8 20.0

.065 .035 1.685 1.175 .035 .410 1.290 14.3 436.0 86.0 8.0 15.0

.072 .051 1.260 .944 .040 .285 1.749 14.1 471.5 98.0 8.1 --

.051 .032 1.555 1.340 .017 .225 4.756 14.1 496.0 >120.0 8.0 10.0

.027 .015 1.265 1.110 .014 .175 1.505 13.7 493.5 >120.0 7.9 5.0

.125 .068 7.385 7.040 .031 .555 1.405 13.6 638.5 59.5 7.7 15.0

.126 .094 7.705 7.265 .051 .430 3.447 14.6 718.0 98.0 8.3 10.0

.169 .124 7.570 6.625 .038 .565 4.118 15.1 735.5 80.0 8.2 30.0

.210 .185 8.145 7.260 .033 .555 2.900 14.6 767.0 94.5 8.0 15.0

.183 .122 6.300 5.475 .056 .655 2.800 14.1 706.5 49.0 8.2 10.0

.115 .091 5.270 4.910 .043 .390 1.834 16.5 659.0 110.0 8.3 10.0

.074 .049 11.040 10.695 .022 .440 2.124 15.5 627.5 84.5 8.2 5.0

.116 .056 7.050 6.670 .090 .675 5.935 17.9 749.5 49.0 8.4 15.0

.084 .060 7.185 6.730 .020 .395 5.185 15.1 798.5 89.0 8.0 40.0

.370 .324 5.235 4.370 .025 .690 3.240 16.8 770.0 62.5 8.5 30.0

.114 .078 4.585 3.815 .045 .455 2.902 16.2 747.5 72.0 8.0 110.0

.095 .066 11.385 10.550 .041 .435 2.746 14.3 661.0 50.5 7.5 55.0

.093 .066 1.361 .590 .055 .805 3.907 15.9 546.5 >120.0 8.1 80.0

.066 .038 3.765 3.405 .032 .370 1.220 12.2 545.5 105.0 7.6 15.0

.100 .031 2.930 2.210 .030 .680 3.720 14.4 486.0 >120.0 7.5 45.0

.115 .063 1.465 1.110 .050 .350 1.503 12.3 356.0 106.0 7.5 10.0

.057 .025 4.675 4.270 .026 .405 1.438 14.4 670.0 70.5 8.0 10.0

.059 .034 2.890 2.515 .021 .305 1.725 13.4 534.0 88.5 7.5 10.0

.031 .020 1.127 .852 .035 .210 .939 15.9 496.5 >120.0 8.1 5.0
102 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

106 Trib Otter Cr 054066478 DFA-39 4 90.2806 43.0767 2001 26.5 0.0046

107 Bear 05406670 DFA-42 4 90.1756 43.3272 2001 43.8 .0101

108 Horse 05406783 DFA-35 4 90.4200 43.3725 2001 19.1 .0103

109 Brush 05406788 DFA-32 4 90.4147 43.3483 2001 14.0 .0107

110 East Mill 05407010 DFA-37 4 90.5258 43.3397 2001 26.3 .0092

111 Trib 1 Dead Cr 05424071 SWTP-10 4 88.7000 43.3428 2001 13.7 .0071

112 Johnson Cr – 

Farmington

05425534 SWTP-11 2 88.7047 43.1228 2001 8.0 .0061

113 Calamus Cr 05425913 SWTP-13 4 88.9044 43.4347 2001 35.2 .0110

114 Schultz Cr 05425919 SWTP-31 2 88.7894 43.4325 2001 12.9 .0105

115 Pratt Cr 05425928 SWTP-25 4 88.7189 43.4228 2001 9.2 .0126

116 Trib Pratt Cr 05425929 SWTP-12 4 88.7258 43.3939 2001 4.6 .0114

117 Casper Cr 05425935 SWTP-26 4 88.7647 43.3094 2001 10.5 .0025

118 Scuppernong 05426390 SWTP-41 2 88.5061 42.9022 2001 35.7 .0068

119 Door Cr 05429560 SWTP-15 4 89.2392 43.0839 2001 15.7 .0048

120 Little Door Cr 05429590 SWTP-30 4 89.1725 43.0289 2001 6.0 .0050

121 Branch Mineral Point 05432140 DFA-17 4 90.1722 42.9589 2001 8.3 .0077

122 Gill 05436204 SWTP-49 4 89.4678 42.8103 2001 12.3 .0081

123 Baker 05545102 SWTP-20 4 88.5392 42.7061 2001 21.0 .0044

124 Spring Brook 05545118 SWTP-14 4 88.3639 42.7169 2001 12.7 .0099

125 Ore 05545187 SWTP-43 2 88.3994 42.6400 2001 28.4 .0055

126 Bassett Cr 05545955 SWTP-05 2 88.2278 42.5406 2001 11.8 .0090

127 West Branch 

Nippersink

05548159 SWTP-42 2 88.3636 42.5181 2001 26.2 .0082

128 White Cr 04073462 SWTP-50 2 88.9283 43.8161 2001 9.1 .0198

129 Pumpkinseed Cr 04081480 SWTP-32 3 88.8197 44.0936 2001 5.8 .0034

130 Spring Bk 04081605 SWTP-33 3 88.6958 44.0189 2001 26.4 .0059

131 Daggets Cr 04081775 SWTP-39 3 88.5994 44.1414 2001 10.4 .0030

132 Van Dyne Cr 04082580 SWTP-29 3 88.5194 43.8792 2001 14.3 .0007

133 Trib 1 West Branch 

Fond Du Lac

04082831 SWTP-28 3 88.7006 43.8800 2001 11.8 .0067

134 Mill Cr 040842515 SWTP-34 3 88.3111 44.0792 2001 8.7 .0035

135 Kankapot Cr 04084479 SWTP-38 4 88.2542 44.2472 2001 11.7 .0007

136 Molash 040852095 SWTP-23 3 87.5342 44.1811 2001 21.2 .0086

137 Grimms 040854193 SWTP-37 3 87.8619 44.1517 2001 13.8 .0022

138 Pine Cr – Newton 0408543802 SWTP-36 3 87.7219 44.0039 2001 16.2 .0035

139 Point Cr 04085439 SWTP-35 3 87.7314 43.9692 2001 45.5 .0028
Appendixes 103

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.064 0.050 2.455 2.240 0.025 0.230 1.148 15.7 533.0 >120.0 8.1 10.0

.086 .034 1.740 1.390 .033 .355 2.535 12.4 488.5 102.5 7.9 10.0

.053 .031 .882 .604 .033 .235 2.015 14.0 393.0 105.0 8.0 40.0

.051 .029 1.034 .724 .037 .285 2.448 14.2 484.5 >120.0 8.1 20.0

.044 .021 .936 .669 .026 .255 2.112 16.1 477.5 >120.0 8.2 35.0

.352 .190 2.407 .013 .404 2.350 9.401 17.9 711.5 75.0 7.1 140.0

.159 .097 3.132 1.115 .238 2.100 1.293 16.4 743.0 90.0 8.1 141.0

.253 .082 1.906 .090 .107 1.700 10.411 17.3 576.0 50.0 7.2 110.0

.071 .027 8.485 8.035 .054 .450 2.923 13.2 826.0 47.5 7.5 20.0

.039 .021 4.015 3.485 .017 .385 2.786 14.4 756.0 >120.0 7.5 25.0

.109 .081 3.265 2.710 .076 .730 2.435 16.7 991.5 96.0 7.7 50.0

.239 .163 5.125 4.260 .056 .950 3.109 16.3 740.5 77.5 7.5 50.0

.028 .014 1.301 .228 .042 1.060 1.626 19.0 579.5 >120.0 8.0 130.0

.127 .066 8.385 7.760 .039 .670 1.640 13.3 819.0 33.0 8.1 10.0

.056 .029 13.205 12.750 .021 .330 1.185 13.2 736.5 49.0 8.0 15.0

.107 .056 8.145 7.690 .050 .495 3.017 16.5 830.5 50.0 8.0 5.0

.093 .066 5.820 5.220 .027 .480 1.879 14.9 597.0 66.0 8.2 40.0

.112 .088 4.082 3.359 .029 .750 3.820 18.2 762.5 105.0 8.0 25.0

.038 .016 9.685 9.215 .018 .485 2.168 16.5 693.0 92.5 8.3 15.0

.123 .085 4.710 4.005 .039 .740 4.152 16.6 718.5 55.0 8.0 15.0

.237 .159 6.240 5.370 .151 .975 1.477 17.4 1405.0 93.5 7.9 25.0

.145 .050 7.780 6.905 .136 1.040 14.605 18.4 743.5 27.5 8.0 25.0

.055 .051 21.260 20.550 .017 .185 1.260 11.4 803.0 86.0 8.0 25.0

.162 .093 2.382 .147 .047 .985 10.096 15.6 797.5 56.0 8.0 25.0

.203 .163 5.095 4.385 .052 .710 2.068 17.5 737.0 42.5 8.2 50.0

.258 .106 6.270 4.075 .039 1.200 6.393 15.9 920.0 47.5 7.2 40.0

.741 .553 3.143 .043 .051 2.000 3.038 21.6 824.0 76.0 9.2 80.0

.189 .104 3.400 1.590 .252 1.500 7.112 18.8 744.0 58.0 8.1 80.0

.088 .038 10.465 9.760 .022 .680 2.028 14.7 815.5 44.5 8.1 15.0

.557 .473 9.382 6.760 .122 2.000 5.048 15.7 1023.5 39.5 7.7 55.0

.150 .126 2.395 .891 .068 1.450 1.615 15.5 529.0 >120.0 7.6 110.0

.349 .297 4.945 3.685 .052 1.100 1.665 15.1 912.0 >120.0 7.7 55.0

.162 .119 2.365 1.265 .043 1.030 3.390 16.9 948.5 59.5 8.1 80.0

.247 .204 2.651 1.651 .072 1.040 3.796 17.0 739.0 76.0 8.3 70.0
104 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

140 Pigeon 040854496 SWTP-22 4 87.8583 43.8917 2001 40.7 0.0037

141 Otter Cr – Plymouth 040857005 SWTP-19 3 87.9222 43.7889 2001 24.7 .0118

142 Weedens 04085995 SWTP-24 3 87.7733 43.7175 2001 19.6 .0146

143 Kettle Moraine 04086096 SWTP-07 2 88.2600 43.6517 2001 39.0 .0110

144 West Branch 

Milwaukee

04086125 SWTP-21 4 88.3936 43.6161 2001 36.0 .0075

145 Parnell 04086175 SWTP-01 2 88.1600 43.6478 2001 17.1 .0042

146 East Branch 

Milwaukee

04086177 SWTP-46 1 88.1811 43.6161 2001 93.4 .0051

147 Crooked 04086190 SWTP-03 2 88.1797 43.5978 2001 30.4 .0041

148 Wallace 04086335 SWTP-04 4 88.0864 43.4983 2001 39.3 .0063

149 Hanneman 04086408 SWTP-08 2 87.9589 43.3378 2001 21.7 .0066

150 Mayfield Cr 04086443 SWTP-27 2 88.1814 43.3078 2001 8.8 .0082

151 Friedens 04086465 SWTP-17 2 88.1614 43.3400 2001 10.5 .0052

152 Pigeon Cr – 

Theinsville

04086696 SWTP-06 3 87.9903 43.2508 2001 23.7 .0050

153 Willow Cr – 

Germantown

040870195 SWTP-02 3 88.1428 43.2067 2001 16.4 .0089

154 Little Menomonee 04087050 SWTP-44 3 88.0383 43.2067 2001 18.9 .0067

155 Husher 040872347 SWTP-40 3 87.9200 42.8364 2001 27.0 .0068

156 North Branch Pike 04087243 SWTP-18 3 87.8683 42.7194 2001 11.6 .0052

157 Willow Cr – Waupun 05422990 SWTP-16 4 88.6892 43.6836 2001 12.7 .0081

158 Flynn 05424450 SWTP-45 2 88.3375 43.2106 2001 13.4 .0058

201 Galena 05415000 2-DFA-01 4 90.3778 42.5136 2002 322.9 .0094

202 Skinner Cr – Klondyke 05434240 2-DFA-02 4 89.7444 42.6253 2002 90.6 .0068

203 East Branch Pecatonica 05433000 2-DFA-03 4 89.8611 42.7856 2002 571.4 .0062

204 Little Sugar 05436280 2-DFA-04 4 89.6319 42.8172 2002 57.6 .0060

205 West Branch Sugar – #1 05436010 2-DFA-05 4 89.5972 42.9031 2002 84.9 .0084

206 Platte – Rockville 05414000 2-DFA-06 4 90.6403 42.7319 2002 367.2 .0068

207 Pigeon 05413415 2-DFA-07 4 90.8161 42.7864 2002 54.4 .0066

208 Rattlesnake 05413449 2-DFA-08 4 90.9411 42.7817 2002 109.7 .0058

209 Blake 05413245 2-DFA-10 4 90.8583 42.8692 2002 85.8 .0056

210 Fennimore 05407039 2-DFA-11 4 90.5631 43.0278 2002 39.6 .0030

211 Black Earth 1 05406500 2-DFA-12 4 89.7322 43.1342 2002 112.1 .0217

212 Kickapoo 05408000 2-DFA-13 4 90.6431 43.5750 2002 689.7 .0062

213 Moore 05407428 2-DFA-15 4 90.5967 43.7933 2002 94.1 .0047

214 Coon Cr 05386500 2-DFA-16 4 91.0183 43.7047 2002 201.1 .0076

215 Little La Crosse 

– Sparta

05382500 2-DFA-18 4 90.8403 43.8958 2002 200.2 .0062
Appendixes 105

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.125 0.090 2.950 1.950 0.046 1.090 3.630 16.2 657.5 105.0 7.6 60.0

.104 .066 1.889 1.134 .030 .721 3.700 17.3 672.0 96.5 7.6 40.0

.297 .260 2.859 1.159 .044 1.400 2.475 17.4 789.0 48.0 7.6 110.0

.103 .077 1.593 .297 .049 1.355 2.250 16.9 500.0 >120.0 7.3 120.0

.118 .050 7.160 6.165 .085 1.150 7.276 14.2 832.0 >120.0 7.3 70.0

.087 .077 1.060 .135 .037 .900 2.004 17.2 482.0 103.0 7.9 120.0

.051 .031 .861 .084 .020 .735 2.230 17.3 493.0 >120.0 7.3 110.0

.055 .030 1.144 .209 .038 .885 2.168 16.5 488.5 >120.0 7.8 60.0

.106 .057 2.050 1.125 .028 .755 2.470 15.9 645.0 119.0 7.9 50.0

.068 .043 1.780 .772 .027 .825 2.361 16.4 759.0 >120.0 8.0 55.0

.166 .102 3.790 2.970 .150 .930 1.778 14.8 818.0 29.0 8.2 40.0

.091 .050 3.365 2.750 .011 .725 2.413 14.3 833.0 60.5 8.0 25.0

.053 .035 1.318 .663 .021 .585 1.947 15.8 752.0 102.5 7.8 40.0

.070 .057 1.316 .705 .050 .630 1.927 15.9 935.0 89.0 8.0 60.0

.082 .059 3.320 2.485 .049 .750 2.693 14.6 819.0 67.5 7.5 110.0

.143 .063 4.715 3.085 .036 1.300 5.335 17.2 679.0 23.5 -- 60.0

.053 .021 3.340 2.645 .044 .670 1.400 17.0 895.0 51.5 7.5 30.0

.146 .087 2.025 1.011 .063 1.050 3.579 15.0 756.5 82.0 7.3 110.0

.069 0.034 1.396 .931 .038 .465 1.562 15.0 703.0 88.5 8.0 40.0

.102 .052 7.260 6.940 .014 .325 3.181 17.1 841.2 64.0 8.0 --

.075 .048 4.500 4.200 .024 .300 1.349 15.4 649.0 63.0 7.8 --

.128 .074 4.345 3.775 .037 .375 2.117 16.3 596.3 35.5 7.2 --

.070 .050 3.825 3.425 .024 .285 1.625 13.6 622.0 74.0 7.2 --

.118 .060 6.125 5.680 .032 .460 1.918 12.9 654.0 42.0 7.2 --

.121 .063 5.055 4.735 .017 .330 3.712 15.0 650.3 39.5 7.2 --

.611 .563 6.540 6.110 .007 .425 2.511 16.3 793.7 89.5 7.6 --

.104 .088 8.990 8.680 .007 .325 2.537 16.3 742.3 >120.0 7.7 --

.159 .124 7.925 7.495 .019 .435 1.990 18.1 725.3 80.5 7.8 --

.140 .112 8.690 7.940 .016 .440 2.673 18.5 748.5 66.0 8.1 --

.063 .051 3.350 3.055 .016 .240 1.905 12.4 637.0 >120.0 7.0 --

.122 .069 1.235 .920 .018 .265 1.916 15.9 470.3 64.5 7.8 --

.198 .153 2.125 1.695 .029 .415 2.456 18.3 478.2 >120.0 7.4 --

.043 .028 1.355 1.155 .025 .160 2.071 14.4 301.8 >120.0 7.1 --

.084 .058 1.945 1.750 .017 .215 1.115 15.0 464.7 110.0 7.2 --
106 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

216 Lacrosse 05382325 2-DFA-19 2 90.8106 43.9375 2002 434.1 0.0090

217 Eau Galle 2 05369945 2-DFA-20 4 92.2519 44.8672 2002 124.2 .0100

218 Willow 05341752 2-DFA-21 1 92.7083 45.0117 2002 751.0 .0070

219 Wood 05338955 2-NCHF-01 2 92.6311 45.7853 2002 348.1 .0061

220 Yellow – Barron 053674464 2-NCHF-02 1 91.8300 45.3953 2002 396.1 .0111

221 Hay River 05368000 2-NCHF-03 1 91.9108 45.0478 2002 1083.2 .0111

222 North Fork Eau Claire 05365707 2-NCHF-04 2 90.8492 44.9736 2002 131.8 .0075

223 Big Eau Pleine 05399500 2-NCHF-05 2 90.0794 44.8219 2002 578.6 .0034

224 Black 05381000 2-NCHF-06 2 90.6150 44.5597 2002 1947.1 .0061

225 Yellow – Babcock 05402000 2-NCHF-07 2 90.1219 44.3022 2002 561.3 .0047

226 Little Yellow 05403043 2-NCHF-08 1 90.1764 44.0575 2002 144.5 .0057

227 South Branch Yellow 05403044 2-NCHF-09 1 90.1478 44.0469 2002 144.5 .0025

228 Ten Mile Cr 05401050 2-NCHF-10 1 89.8103 44.2625 2002 173.3 .0108

229 Little Plover 05400650 2-NCHF-11 1 89.5281 44.4736 2002 49.3 .0059

230 Tomorrow 04080798 2-NCHF-12 1 89.3378 44.5244 2002 113.9 .0058

231 Pensaukee – Krakow 04071795 2-NCHF-13 1 88.2764 44.7525 2002 86.7 .0016

232 Pensaukee – 

Pensaukee

04071858 2-NCHF-14 1 87.9533 44.8189 2002 343.1 .0027

233 Middle Branch 

Embarrass

0407809265 2-NCHF-15 1 89.1181 44.8253 2002 254.7 .0046

234 Eau Claire – Kelly 05397500 2-NCHF-16 1 89.5500 44.9181 2002 923.8 .0046

235 Eau Claire – Antigo 05397110 2-NCHF-17 1 89.2339 45.1258 2002 471.0 .0069

236 Spring Brook 2 05397180 2-NCHF-18 1 89.1331 45.1547 2002 93.6 .0011

237 Prairie 05394500 2-NCHF-19 1 89.6497 45.2358 2002 477.2 .0092

238 Skinner 05359698 2-NLF-01 2 90.6994 45.5833 2002 74.8 .0086

239 Spirit 05393500 2-NLF-02 2 89.9797 45.4494 2002 211.3 .0120

240 North Fork Copper 05394079 2-NLF-03 2 89.9247 45.2150 2002 70.3 .0084

241 Hunting 04074720 2-NLF-04 1 89.1142 45.3814 2002 67.9 .0084

242 Wolf River 04074950 2-NLF-05 1 88.7333 45.1900 2002 1182.5 .0107

243 North Branch Pike 04066350 2-NLF-06 1 88.1089 45.5675 2002 238.0 .0102

244 Popple 04063700 2-NLF-07 2 88.4631 45.7636 2002 362.4 .0096

245 Woods 04063774 2-NLF-08 2 88.4600 45.8461 2002 59.9 .0096

246 Pine 04064500 2-NLF-09 2 88.2253 45.8378 2002 1377.9 .0094

247 Brule 04060993 2-NLF-10 2 88.3158 45.9608 2002 990.2 .0096

248 Kaubashine 05392233 2-NLF-11 1 89.8008 45.7994 2002 47.7 .0058

249 Namekagon 05331833 2-NLF-12 1 91.3292 46.1714 2002 326.2 .0129
Appendixes 107

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.092 0.047 1.295 1.040 0.034 0.260 2.321 16.7 185.0 >120.0 7.5 --

.037 .033 1.837 1.415 .019 .330 4.480 14.5 356.7 >120.0 7.3 --

.090 .033 2.890 2.335 .044 .615 14.644 17.3 337.7 112.0 7.9 --

.044 .022 .694 .098 .036 .595 2.770 18.1 191.3 >120.0 6.9 --

.099 .050 1.495 .890 .046 .470 7.079 16.7 178.5 102.5 7.0 --

.095 .053 2.245 1.820 .019 .465 2.110 14.6 320.3 107.5 7.4 --

.155 .097 1.051 .145 .025 .895 5.172 16.8 147.3 106.0 6.9 --

.258 .213 1.648 .692 .031 1.020 3.985 18.6 228.8 97.0 7.6 --

.173 .135 1.178 .255 .019 .910 3.814 19.4 137.0 104.5 8.0 --

.271 .136 1.397 .221 .055 1.250 7.457 17.2 142.5 55.5 7.3 --

.056 .026 1.211 .011 .353 1.200 6.347 14.4 115.8 35.5 6.6 --

.053 .019 1.197 .047 .183 1.150 6.683 16.6 71.2 81.0 6.9 --

.051 .019 4.250 3.280 .029 .950 1.956 14.9 372.8 94.5 7.8 --

.031 .023 8.240 7.985 .007 .315 1.702 13.2 497.0 >120.0 8.0 --

.019 .012 3.215 2.775 .007 .385 1.429 10.9 514.8 >120.0 8.0 --

.132 .103 2.155 1.055 .050 1.035 2.496 15.4 716.0 98.0 7.0 --

.086 .067 1.220 .306 .041 .930 2.368 16.5 552.7 102.0 7.7 --

.027 .020 1.616 1.085 .021 .520 2.631 15.0 450.3 >120.0 8.4 --

.049 .032 1.724 .914 .024 .565 3.239 16.1 244.0 >120.0 8.3 --

.085 .048 1.561 .911 .021 .635 3.971 15.4 195.0 >120.0 7.5 --

.055 .038 5.055 4.650 .024 .405 3.399 11.4 376.2 >120.0 7.2 --

.055 .037 0.600 .072 .015 .515 2.270 16.4 141.3 >120.0 8.1 --

.082 .051 1.177 .012 .045 1.150 4.392 17.5 65.5 110.5 6.5 --

.068 .045 .801 .031 .022 .770 4.823 16.7 77.7 >120.0 7.8 --

.063 .043 .793 .019 .025 .760 2.042 13.8 72.5 >120.0 7.1 --

.068 .046 .408 .013 .021 .385 2.204 17.5 184.8 >120.0 8.1 --

.032 .014 .571 .048 .018 .515 2.801 15.8 186.5 >120.0 7.6 --

.012 .006 .344 .043 .007 .300 .653 15.4 233.5 >120.0 8.2 --

.022 .012 .623 .011 .020 .615 1.180 15.6 149.2 >120.0 7.8 --

.019 .015 .554 .149 .011 .430 .452 12.4 231.3 >120.0 7.9 --

.016 .008 .490 .018 .019 .460 .941 16.1 178.2 >120.0 8.2 --

.016 .006 .298 .088 .007 .210 1.881 14.1 274.2 >120.0 7.8 --

.038 .020 .366 .011 .015 .355 1.939 16.9 111.2 >120.0 7.3 --

.017 .011 .363 .033 .007 .315 1.714 14.8 118.8 >120.0 8.0 --
108 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 1. Stream identification (ID) information, location information, and summary statistics for flow and water-quality data 

collected for each of the 240 studied wadeable streams in Wisconsin—Continued.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; USGS, U.S. Geological Survey; km2, square kilometer; m3/s/km2, cubic meter per 

second per square kilometer; mg/L, milligram per liter; μg/L, microgram per liter; C; degrees centigrade; μS/cm; microSiemen per centimeter; 

m, meter; --, no data collected at site; all water-quality data are median values unless otherwise noted]

ID

(see 

fig. 4)

 Stream name USGS site 

number

Ecoregion 

ID

Phosphorus

zone Longitude Latitude Collection 

year

Watershed 

area

(km2

)

Flow per 

unit area

(m3/s/km2)

250 Totagatic 05333067 2-NLF-13 1 91.6947 46.1672 2002 389.6 0.0053

251 Eau Claire 05331597 2-NLF-14 1 91.6550 46.2506 2002 312.6 .0068

252 Upper Ox 05331585 2-NLF-15 1 91.6625 46.3161 2002 180.3 .0017

253 North Fish Cr 040263491 2-NLF-16 3 91.0619 46.5489 2002 99.3 .0258

254 Bois Brule 04025500 2-NLF-17 1 91.5953 46.5378 2002 343.5 .0141

255 Amnicon 04024570 2-NLF-18 3 92.0706 46.4531 2002 67.7 .0141

256 Upper Tamarack 05335574 2-NLF-19 2 92.2839 46.1644 2002 223.1 .0099

257 Turtle Cr 2 05431486 2-SWTP-01 4 88.8292 42.5972 2002 483.9 .0056

258 Whitewater Cr 05426900 2-SWTP-02 2 88.7025 42.8039 2002 53.3 .0081

259 Token Cr 05427800 2-SWTP-03 4 89.3244 43.1811 2002 63.0 .0114

260 Yahara 05427718 2-SWTP-04 4 89.3525 43.2089 2002 192.4 .0025

261 Oconomowoc 05424440 2-SWTP-05 2 88.3006 43.2192 2002 54.0 .0036

262 Milwaukee 04086600 2-SWTP-06 2 87.9428 43.2803 2002 1571.6 .0033

263 Cedar Cr 04086500 2-SWTP-07 2 87.9786 43.3231 2002 290.7 .0031

264 Sauk 04086017 2-SWTP-08 4 87.8692 43.4703 2002 55.2 .0011

265 Stoney 040863313 2-SWTP-09 4 88.0889 43.5275 2002 53.5 .0022

266 North Branch 

Milwaukee

040863075 2-SWTP-10 4 88.0528 43.5569 2002 132.7 .0055

267 West Branch Rock 05423510 2-SWTP-11 4 88.6856 43.6344 2002 292.2 .0024

268 Onion 04085845 2-SWTP-13 4 87.8200 43.6967 2002 243.5 .0025

269 South Branch 

Sheboygan

04085480 2-SWTP-14 4 88.2511 43.8092 2002 71.3 .0021

270 Meeme 04085454 2-SWTP-15 4 87.8125 43.9222 2002 49.7 .0024

271 Silver Cr 04085435 2-SWTP-16 3 87.6806 44.0547 2002 54.6 .0031

272 South Branch 

Manitowoc

04085395 2-SWTP-17 2 88.1181 44.0247 2002 283.1 .0013

273 Manitowoc 04085427 2-SWTP-18 3 87.7142 44.1072 2002 1359.0 .0029

274 East Twin 04085281 2-SWTP-19 2 87.6364 44.2378 2002 285.8 .0043

275 Neshota 04085305 2-SWTP-20 4 87.8142 44.3928 2002 71.8 .0019

276 Kewaunee 04085200 2-SWTP-21 4 87.5564 44.4583 2002 328.6 .0035

277 East 04085109 2-SWTP-22 4 88.0797 44.3867 2002 122.2 .0021

278 Duck Cr 04072150 2-SWTP-23 3 88.1297 44.5358 2002 280.7 .0230

301 Vismal Cr 05381195 3-NCHF-06 2 90.7647 44.3869 2003 10.5 .0061

302 Levis Cr 05381350 3-NCHF-07 1 90.8064 44.3117 2003 106.1 .0051

303 Ditch #6 South Branch 

Ten Mile Cr

05401035 3-NCHF-11 1 89.6064 44.2783 2003 39.2 .0048

304 South Branch Suamico 040719496 3-NCHF-15 2 88.1867 44.6175 2003 38.8 .0017

305 West Branch Red 04077601 3-NCHF-17 1 88.9882 44.9644 2003 84.0 .0100
Appendixes 109

Total 

phosphorus

(mg/L)

Dissolved 

phosphorus

(mg/L)

Total 

nitrogen

(mg/L)

Dissolved 

nitrite plus 

nitrate

(mg/L)

Dissolved 

ammonia

(mg/L)

Total 

Kjeldahl 

nitrogen

(mg/L)

Suspended 

chlorophyll 

a

(μg/L)

Average 

temperature

(degrees C)

Specific 

conductance

(μS/cm)

Secchi 

depth

(m)

August 

pH 

(standard 

units)

Average 

color 

(standard 

units)

0.034 0.022 0.586 0.015 0.024 0.560 1.706 16.9 84.2 >120.0 7.2 --

.017 .008 .241 .011 .007 .230 2.197 18.1 130.2 >120.0 7.7 --

.019 .012 .191 .008 .007 .180 1.367 14.2 127.5 >120.0 7.4 --

.026 .018 .131 .030 .007 .070 .857 9.5 331.0 >120.0 7.7 --

.027 .017 .353 .012 .007 .340 2.342 13.1 260.3 >120.0 7.2 --

.036 .022 1.248 .008 .038 1.240 1.142 16.5 115.0 86.0 5.5 --

.041 .027 1.161 .011 .024 1.150 1.081 17.3 118.8 92.5 6.4 --

.073 .028 9.505 9.090 .007 .575 8.421 18.4 768.8 95.0 7.3 --

.023 .014 2.545 2.170 .007 .270 1.717 15.5 661.0 >120.0 7.1 --

.070 .030 9.020 8.620 .020 .435 5.690 14.6 741.3 44.0 7.1 --

.089 .060 8.720 8.190 .018 .510 3.298 16.1 738.3 101.0 6.7 --

.035 .010 2.170 1.305 .036 .860 4.128 19.7 643.7 >120.0 8.2 --

.116 .064 2.095 1.150 .028 .880 7.619 18.1 808.3 107.5 8.6 --

.104 .041 1.677 1.105 .017 .775 10.850 18.6 761.5 110.0 8.3 --

.605 .405 3.476 1.748 .089 1.700 10.075 17.6 883.8 25.5 8.9 --

.069 .050 2.250 1.445 .029 .775 2.286 18.6 647.3 >120.0 8.1 --

.170 .098 3.750 2.615 .069 1.035 7.707 18.3 708.5 41.5 8.1 --

1.641 1.460 7.935 6.995 .075 1.050 10.947 15.9 1205.2 26.5 7.5 --

.196 .120 2.014 .895 .029 .975 23.512 17.4 688.8 51.0 7.8 --

.119 .086 3.265 2.430 .032 .890 2.422 18.2 763.8 109.0 8.0 --

.103 .078 1.825 1.180 .034 .690 5.100 17.7 590.2 92.5 7.4 --

.201 .153 2.955 1.825 .042 1.055 3.378 18.1 709.5 89.0 8.0 --

.242 .081 5.430 3.780 .058 1.750 38.007 19.8 927.7 27.0 8.3 --

.247 .102 2.481 .665 .023 1.950 36.629 19.1 672.5 35.5 8.5 --

.111 .060 3.340 2.400 .057 1.000 3.517 17.8 668.0 45.0 8.0 --

.203 .158 .777 .153 .055 .670 1.926 15.0 695.2 41.5 7.6 --

.076 .051 3.945 3.285 .052 .755 3.243 17.9 691.0 110.0 8.0 --

.412 .311 1.858 .680 .094 1.300 2.054 16.0 816.8 30.5 7.3 --

.160 .130 1.653 .396 .029 1.195 3.996 16.9 775.2 72.0 8.5 --

.021 .015 .391 .194 .014 .215 .917 14.1 62.5 >120.0 7.5 --

.023 .011 .575 .365 .014 .295 1.094 14.9 96.5 >120.0 7.6 --

.058 .046 7.960 7.395 .019 .435 2.285 15.8 430.0 >120.0 8.5 --

.247 .040 1.700 1.285 .026 .460 3.763 17.5 835.0 >120.0 8.0 --

.056 .204 3.755 1.825 .039 1.405 2.340 15.3 394.5 >120.0 8.1 --
110 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin. All data collected by the 

Wisconsin Department of Natural Resources. 

[CR, Creek; TRIB, Tributary; BR, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

1 Onion 4.35 0.27 0.36 2.03 0.00 0.00 100.00 0.30

2 Thompson 4.29 .22 .35 4.04 11.81 10.42 77.78 .17

3 Parker 4.95 .09 .17 19.70 5.48 67.14 27.38 .00

4 Catlin 2.89 .18 .22 12.40 7.62 35.24 57.14 .02

5 Leo 3.12 .23 .32 3.42 12.96 1.85 85.19 .11

6 Lower Ox 14.18 .27 .37 2.80 1.16 42.82 56.02 .03

7 Lord 4.51 .22 .31 4.35 18.07 28.31 53.61 .01

8 Fivemile 4.38 .12 .16 3.50 19.31 14.48 66.21 .06

9 Cap 5.05 .38 .48 2.50 4.73 .00 95.27 .07

10 Spring Cr 5.52 .17 .24 2.31 2.65 12.39 84.96 .14

11 Mosquito Br 3.67 .17 .25 9.90 14.02 44.86 41.12 .02

12 Smith Lake 3.07 .27 .36 4.85 4.55 .00 95.45 .10

13 Fiddler 4.09 .10 .13 2.10 .00 .00 100.00 .05

14 Spring Lake 8.92 .23 .33 .82 .00 .00 100.00 .12

15 Rainbow 6.96 .16 .23 1.54 .00 .00 100.00 .06

16 Dody Brook 4.80 .40 .54 8.08 73.00 .00 27.00 .14

17 Swan 4.46 .27 .36 2.58 46.62 18.92 34.46 .00

18 Becky 3.00 .20 .27 -- .00 61.86 38.14 .01

19 Hay 5.30 .43 .61 .52 .00 .00 100.00 .20

20 Soft Maple 7.59 .46 .56 .91 19.93 14.59 65.48 .04

21 Mcdermott 4.57 .40 .48 3.30 6.49 .00 93.51 .14

22 Meadow Cr 1.37 .20 .24 2.40 .00 3.26 96.74 .10

23 Gilbert Cr 2.47 .18 .22 6.63 29.00 17.00 54.00 .02

24 Trib 1 Shoulder Cr 4.74 .35 .41 1.82 .00 .00 100.00 .37

25 Crazy Horse Cr 3.20 .39 .48 4.48 13.00 .00 87.00 .12

26 Alder Cr 2.27 .19 .24 2.18 9.00 .00 91.00 .19

27 Sailor Cr 4.27 .19 .27 4.00 12.00 15.00 73.00 .06

28 Knuteson 9.37 .40 .52 3.60 28.37 12.77 58.87 .02

29 South Fork Hemlock 3.57 .11 .18 5.40 4.20 23.08 72.73 .02

30 Little Soft Maple 4.45 .26 .31 4.50 52.00 26.00 22.00 .01

31 Alvin 3.05 .28 .36 2.40 .00 .00 100.00 .09

32 North Otter 4.12 .18 .24 4.10 .00 37.59 62.41 .02

33 North Fork Thunder 4.24 .33 .45 .82 14.38 .00 85.63 .22

34 Waupee 5.13 .36 .52 2.25 19.38 .00 80.63 .36

35 Trout 5.50 .26 .32 2.80 31.20 15.38 53.42 .01

36 South Fork Popple 4.47 .65 .74 .98 .00 .00 100.00 .25

37 Mosquito Cr 4.51 .34 .48 1.16 16.20 .00 83.80 .30

38 Hay Meadow 3.34 .22 .32 2.54 14.55 .00 85.45 .06
Appendixes 111

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

2.40 85.21 5.42 87.29 0.00 0.00 16.53 78.23 18.13 8.90

3.02 71.35 23.02 77.50 .00 .00 7.60 42.71 34.58 9.46

.77 .67 25.29 6.15 .00 .00 .71 56.15 .58 10.00

.00 36.35 24.27 47.92 .00 .00 6.83 86.77 7.29 10.00

5.83 65.10 11.35 83.33 .00 3.13 4.29 60.31 39.58 10.00

7.92 47.19 22.92 39.48 .00 9.69 3.04 .10 .42 10.00

1.48 28.07 28.41 26.70 .00 .00 4.24 61.14 20.23 10.00

41.77 22.81 25.21 68.44 .21 5.73 .00 51.88 6.46 10.00

33.65 41.88 16.46 80.52 .00 .83 14.07 60.21 6.46 10.00

43.85 40.94 3.23 93.33 .00 31.25 .54 22.50 1.46 9.67

.00 42.71 31.88 50.21 .00 .00 9.13 89.48 6.25 10.00

24.69 67.08 5.83 94.06 .00 36.88 18.50 20.52 7.08 .63

1.56 64.06 33.02 67.50 .00 .00 .00 70.00 1.25 10.00

8.96 68.85 6.98 88.96 .00 9.58 1.92 46.98 1.04 10.00

34.69 52.81 .00 100.00 .00 13.75 4.33 17.81 2.50 10.00

32.12 41.25 2.88 94.81 .00 1.54 29.43 58.17 7.12 9.23

.63 33.96 33.02 25.83 20.00 .00 14.21 28.75 9.79 8.58

.63 7.08 10.42 18.13 13.96 .00 7.52 13.65 10.00 .00

22.29 37.60 .21 100.00 .00 20.42 1.34 13.33 6.67 10.00

7.29 26.35 30.52 42.60 .00 .00 11.44 82.40 5.21 10.00

21.88 32.50 26.46 74.38 .00 51.15 38.53 .00 5.21 10.00

29.97 26.69 11.09 76.09 .47 2.84 11.93 27.37 11.15 20.00

6.04 29.09 29.19 32.94 5.29 4.35 11.48 19.64 8.44 20.00

61.20 23.10 .39 99.19 16.67 30.05 16.18 2.50 5.26 12.21

31.46 11.15 2.76 91.25 .00 .60 22.99 57.11 4.06 19.31

30.13 23.65 .83 98.83 .00 4.66 6.19 69.45 5.94 18.74

4.69 40.68 40.42 43.72 .36 2.86 6.22 74.64 13.07 19.48

5.63 33.44 36.04 50.83 .00 .00 7.59 49.79 12.29 7.92

1.04 54.90 25.00 73.85 .00 .00 8.87 86.77 21.67 10.00

1.59 22.84 14.20 29.20 .00 .57 6.91 56.93 22.27 10.00

6.04 63.54 16.67 76.15 .00 11.46 13.34 9.48 13.54 9.92

1.98 34.79 39.48 36.25 .00 2.71 14.70 84.06 5.42 10.00

.00 90.38 1.15 99.04 .00 2.60 26.03 69.33 10.77 10.00

24.62 55.67 .00 100.00 .00 5.10 9.55 33.46 .38 10.00

10.31 35.31 34.27 35.83 9.79 .00 1.32 69.48 72.50 10.00

45.73 8.33 .42 99.11 .10 8.39 45.74 .00 .00 20.00

9.27 87.19 .00 100.00 .00 1.56 15.72 11.15 7.50 10.00

5.83 77.60 9.38 79.58 .00 21.15 16.36 25.10 2.08 10.00
112 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

39 Cedar Springs 2.42 0.22 0.30 1.97 14.00 0.00 86.00 0.07

40 Skunk Cr 4.02 .48 .61 1.58 .00 3.85 96.15 .12

41 Jennie 5.31 .15 .23 5.44 .00 9.44 90.56 .08

42 Trout 2.62 .13 .19 2.77 .00 .00 100.00 .08

43 Muskellunge – 

Heafford Junction

6.20 .28 .37 .79 1.38 .00 98.62 .10

45 Johnson 6.77 .20 .34 1.60 .00 .00 100.00 .09

46 Threemile 3.23 .17 .24 1.16 .00 .00 100.00 .10

47 Raeder Cr 3.74 .15 .20 6.49 11.00 35.00 54.00 .01

48 Hamann Cr 4.95 .20 .26 4.22 16.00 14.00 70.00 .01

49 East Fork Hamann 1.78 .21 .25 3.39 11.00 23.00 66.00 .02

50 Hamann Trib 2.07 .17 .21 6.22 6.00 38.00 56.00 .01

51 Widow Green 2.62 .26 .32 1.90 .00 .00 0.00 .16

52 North Fork Willow 6.42 .78 .89 1.76 100.00 .00 0.00 .05

53 Black Brook 4.57 .23 .30 4.47 4.55 2.27 93.18 .04

54 South Fork Willow 3.72 .19 .29 2.41 27.14 .00 72.86 .19

55 Hutton Cr 6.79 .31 .42 2.60 55.00 8.75 36.25 .06

56 Tenmile Cr 6.26 .29 .37 2.80 22.43 2.76 74.81 .02

57 Cr 12–13 1.15 .18 .23 6.57 2.78 .00 97.22 .17

58 Running Valley 4.59 .52 .72 2.24 17.92 4.17 77.92 .11

59 Cr 1–8 1.07 .17 .20 3.33 5.93 .00 94.07 .23

60 Cr 1–12 2.13 .20 .26 2.80 .00 .00 100.00 .75

61 18-mile 1.68 .31 .37 4.40 .00 .00 100.00 .11

62 Cady 4.63 .21 .27 8.24 10.27 31.35 58.38 .00

63 Eagle 2.88 .28 .34 5.10 2.79 12.40 84.80 .17

64 Joos 3.57 .75 .86 5.80 6.61 .00 93.39 .20

65 Trout Run 2.72 .19 .25 4.10 1.94 9.71 88.35 .10

66 Bohris 4.07 .19 .27 4.10 6.11 18.32 75.57 .15

67 South Branch Oneill Cr 3.42 .20 .25 2.67 28.00 7.00 65.00 .03

68 Unnamed Trib 1 

East Fork Black

3.50 .22 .28 3.67 31.00 31.00 38.00 .02

69 Unnamed Trib 1 Rock Cr 2.11 .16 .23 2.16 2.06 .00 97.94 .16

70 Bloody Run 3.23 .11 .16 2.30 .00 .00 100.00 .18

71 Beaver Cr 3.27 .26 .31 2.34 29.00 3.00 68.00 .06

72 Tributary To Beaver Cr 3.10 .22 .27 .38 15.00 15.00 70.00 .04

73 North Fork Hemlock Cr 5.17 .17 .22 3.43 28.87 18.56 52.58 .01

74 Mormon 6.58 .22 .34 4.43 7.72 17.83 74.45 .02

75 Timber Coulee 4.32 .27 .37 4.97 18.33 5.00 76.67 .01
Appendixes 113

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

11.02 64.66 1.02 98.30 0.00 22.95 17.09 13.64 1.82 10.00

5.00 65.00 10.96 87.12 .00 5.29 8.82 3.65 .00 9.50

26.67 54.27 17.29 85.73 .00 4.69 2.27 .21 1.46 10.00

.77 76.63 13.17 79.71 3.27 .77 6.80 26.44 15.96 10.00

26.77 64.69 1.67 98.33 .00 .00 1.81 34.90 5.00 10.00

5.21 81.67 9.48 87.19 .00 .00 14.91 71.67 8.13 10.00

15.00 69.90 .00 100.00 1.04 22.92 7.96 31.25 3.75 10.00

.99 20.18 32.08 20.36 2.06 .18 6.15 69.43 15.10 20.00

2.03 14.71 44.40 14.87 20.08 3.07 6.69 70.31 9.43 19.70

10.21 18.02 21.85 33.91 3.49 .23 12.81 58.59 6.77 17.81

4.11 13.13 18.85 18.98 12.40 2.27 10.40 24.14 3.75 15.60

22.50 75.42 .00 100.00 .00 6.56 .56 .00 6.25 .00

31.54 23.46 17.12 64.90 2.21 8.37 21.11 7.12 1.15 10.00

10.58 53.08 27.60 68.46 .00 .00 3.41 63.94 35.00 9.65

26.06 47.02 16.83 84.04 .10 .19 1.42 67.12 56.54 9.23

26.25 31.44 14.23 67.69 2.69 .00 1.59 37.21 70.19 8.62

6.73 38.08 39.52 47.69 .00 .00 3.20 64.04 11.15 9.08

24.81 46.44 .38 99.81 .00 12.40 1.40 30.77 76.54 10.00

14.23 72.50 1.54 94.23 .96 2.02 7.20 16.15 9.81 10.00

34.90 41.04 .00 100.00 .00 3.75 6.48 19.38 63.33 10.00

66.92 .38 .00 100.00 .00 5.00 .00 73.17 67.12 9.92

5.52 89.69 .00 100.00 .00 .00 10.14 .00 8.33 10.00

10.10 2.29 18.33 20.63 6.04 21.46 6.64 29.17 17.29 10.00

31.46 9.90 11.15 79.38 .21 .00 2.33 .00 4.58 8.83

64.13 25.48 .38 98.27 .00 1.73 28.27 9.52 22.69 10.00

10.52 62.08 6.35 76.56 4.17 .83 .00 .00 43.75 .00

15.52 67.60 5.94 87.71 .31 1.04 .00 31.88 23.96 9.38

14.40 21.46 28.13 40.16 13.59 17.50 9.12 5.81 24.27 .21

.76 25.70 29.61 26.54 8.18 3.20 11.55 20.73 21.25 19.86

3.44 89.38 .78 98.31 .00 .00 5.33 76.61 18.49 18.45

13.54 66.98 3.54 97.71 .00 9.17 .64 84.38 28.33 12.38

3.46 25.89 40.29 34.53 3.39 .00 10.73 62.66 20.68 10.78

7.76 33.20 37.19 48.15 2.42 2.84 8.18 52.19 20.47 20.00

3.23 13.07 30.36 16.20 19.35 .31 1.99 90.60 17.34 20.00

26.25 14.90 17.81 51.56 1.04 45.63 .42 33.23 .00 14.88

13.33 11.46 29.17 41.56 14.06 18.44 7.84 51.25 5.83 5.17
114 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

76 Spring Coulee 7.32 0.27 0.43 4.30 24.80 26.42 48.78 0.07

77 Rush-02 3.53 .19 .24 -- 10.10 63.64 26.26 .01

78 Beaver 2.63 .29 .37 3.40 35.14 24.32 40.54 .01

79 Dilly 2.13 .28 .31 5.51 .00 33.62 66.38 .00

80 Trib West Branch Baraboo 2.96 .26 .31 -- 26.67 14.29 59.05 .04

81 Crooked 4.76 .38 .54 1.42 28.81 .00 71.19 .14

82 Moore 6.43 .33 .41 5.23 6.57 32.86 60.56 .00

83 Warner Br 2.34 .21 .24 5.28 6.09 22.61 71.30 .02

84 Warner 6.99 .41 .57 2.81 12.85 11.17 75.98 .12

85 Otter Cr – Lafarge 4.50 .30 .43 2.31 28.82 32.53 38.65 .04

86 Harrison 2.35 .41 .49 2.46 39.04 3.59 57.37 .08

87 Mccartney Br 2.04 .20 .25 5.23 18.00 30.00 52.00 .04

88 Hackett Br 3.41 .16 .20 10.00 .00 55.00 45.00 .00

89 Kuenster 6.11 .23 .33 5.24 .00 34.07 65.93 .05

90 Muskellunge Cr – Beetown 4.55 .33 .45 4.40 28.74 9.58 61.68 .06

91 Bull 5.32 .32 .41 4.50 29.03 25.35 45.62 .11

92 Willow 4.44 .23 .30 5.00 .00 20.14 79.86 .02

93 Mounds Br 1.93 .22 .28 4.76 4.81 43.27 51.92 .01

94 Young Br 3.09 .22 .28 15.86 19.80 36.63 43.56 .01

95 Mcadam Br 2.45 .22 .28 10.97 14.14 29.29 56.57 .02

96 Indian Cr – Dickeyville 1.36 .07 .10 12.01 .00 85.00 15.00 .00

97 Kieler Cr 1.89 .16 .20 7.35 6.67 28.57 64.76 .01

98 Apple 4.87 .43 .53 4.50 17.81 15.07 67.12 .03

99 Trib 1 French Spring Cr 1.39 .18 .23 3.95 21.43 6.12 72.45 .10

100 Rowan 3.72 .52 .70 2.30 39.23 .00 60.77 .10

101 Hinkson 3.47 .18 .24 1.30 5.13 .00 94.87 .11

102 North Branch Honey 2.61 .32 .38 7.30 .00 .00 100.00 .14

103 Moen 1.87 .16 .22 8.33 13.15 34.74 52.11 .04

104 Trout Cr – Barneveld 4.47 .46 .66 6.02 25.81 16.77 57.42 .12

105 Lowery 2.65 .17 .28 5.39 28.46 8.13 63.41 .17

106 Trib Otter Cr 5.73 .28 .38 4.60 29.93 19.20 50.87 .06

107 Bear 3.49 .37 .53 2.70 23.49 .00 76.51 .07

108 Horse 2.67 .25 .35 2.80 3.57 .00 96.43 .16

109 Brush 2.47 .29 .36 1.70 28.64 17.27 54.09 .08

110 East Mill 3.34 .33 .38 3.36 20.00 27.08 52.92 .01

111 Trib 1 Dead Cr 1.63 .38 .46 .56 .00 .00 100.00 .31

112 Johnson Cr – Farmington 2.32 .26 .33 .74 .00 .00 100.00 .50

113 Calamus Cr 3.43 .35 .39 1.95 .00 .00 100.00 .13
Appendixes 115

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

24.48 44.58 10.00 64.48 0.10 32.29 1.53 69.90 17.50 18.83

5.42 11.46 40.42 21.25 .21 .10 .89 67.19 13.33 16.38

7.19 10.10 46.25 18.54 5.83 .00 7.30 5.73 8.13 20.00

6.98 12.50 27.81 18.75 3.33 .00 5.21 2.29 2.71 .00

9.58 24.17 38.33 36.25 .00 .00 11.00 41.98 12.50 18.92

59.61 25.39 6.41 88.28 .39 47.66 3.91 .00 .47 17.72

3.33 11.88 17.50 17.19 .63 .00 3.43 56.67 19.58 6.71

1.98 34.38 29.79 35.10 10.00 .00 4.33 .00 32.92 .00

5.42 60.94 23.96 68.65 3.75 .00 3.00 53.02 28.33 20.00

10.63 29.61 24.14 42.58 .00 .00 1.32 76.64 29.22 23.44

14.46 28.48 20.54 65.18 .00 15.45 19.88 .00 4.46 .00

32.47 4.92 26.90 46.48 2.84 1.90 11.18 .00 21.41 .00

9.48 3.46 15.36 21.02 45.91 2.21 2.40 1.43 21.46 .00

41.46 3.65 18.75 61.35 22.81 6.25 .00 39.17 22.92 .00

48.46 2.60 15.87 69.52 10.67 28.85 8.13 15.48 26.35 .00

46.25 6.52 17.68 64.55 15.98 17.32 3.21 37.95 38.57 .00

16.46 16.04 15.00 49.38 14.48 19.90 .49 42.71 31.46 .00

15.41 5.79 44.28 29.13 3.99 2.88 8.41 .00 24.13 .00

18.05 1.85 14.95 33.75 19.51 .96 4.39 50.99 28.33 19.78

23.95 5.18 18.88 42.47 19.84 14.87 6.08 5.83 25.83 .00

7.55 6.80 29.92 21.95 6.98 .00 .00 69.51 28.96 17.71

25.28 2.33 15.90 49.75 13.73 1.00 6.46 6.98 9.50 11.03

8.54 9.06 38.75 24.38 14.17 2.81 1.11 .00 38.75 10.00

24.17 50.18 1.61 96.41 .00 .18 20.52 8.98 3.85 16.83

51.44 2.02 10.48 77.60 .00 18.75 9.13 .77 7.50 10.00

13.94 50.87 .48 98.27 .00 .00 1.40 71.73 15.77 10.00

42.40 52.40 2.08 95.42 .10 10.10 4.14 .10 60.63 .00

.54 59.73 20.71 61.52 .54 7.32 7.95 .00 7.86 20.57

15.52 44.79 17.50 68.13 .00 27.29 5.85 .00 33.13 20.00

80.39 4.77 5.39 82.89 .00 54.77 1.12 .00 19.06 .00

39.06 19.90 29.06 67.92 .00 .52 .00 73.33 34.38 .00

22.50 34.23 16.15 76.54 .00 7.40 .79 44.90 28.46 30.00

5.77 88.08 3.17 97.12 .00 .77 1.25 .00 40.00 .00

3.96 40.73 46.56 43.02 .21 .00 11.29 .00 19.79 18.13

3.84 36.52 34.46 32.41 .36 1.70 7.62 .00 8.04 10.00

42.19 .78 1.35 98.88 .00 5.42 30.51 .00 .16 16.61

12.92 81.95 .00 100.00 .00 .00 13.54 6.59 1.25 18.88

60.73 13.26 2.66 96.33 .42 47.71 43.37 .00 1.56 17.85
116 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

114 Schultz Cr 2.12 0.25 0.32 4.62 0.00 0.00 100.00 0.07

115 Pratt Cr 2.80 .29 .34 1.60 .00 .00 100.00 .22

116 Trib Pratt Cr 1.95 .21 .26 1.33 .00 .00 100.00 .26

117 Casper Cr 1.46 .15 .19 5.04 4.08 12.24 83.67 .07

118 Scuppernong 3.11 .47 .54 .70 .00 .00 100.00 .08

119 Door Cr 2.25 .32 .40 1.37 .00 .00 100.00 .14

120 Little Door Cr 3.10 .17 .22 3.89 .00 13.00 87.00 .08

121 Branch Mineral Point 2.28 .19 .24 4.32 21.00 41.00 38.00 .01

122 Gill 2.56 .22 .26 2.82 .00 .00 100.00 .07

123 Baker 2.60 .18 .24 7.60 18.69 26.17 55.14 .02

124 Spring Brook 4.07 .25 .31 7.20 16.67 26.39 56.94 .02

125 Ore 4.75 .31 .39 2.61 36.80 11.20 52.00 .02

126 Bassett Cr 2.60 .17 .21 3.86 .00 25.00 75.00 .04

127 West Branch Nippersink 5.41 .27 .40 2.23 9.71 .00 90.29 .11

128 White Cr 3.35 .24 .31 4.67 9.03 22.22 68.75 .10

129 Pumpkinseed Cr 2.17 .40 .48 1.71 .00 .00 100.00 .09

130 Spring Bk 2.58 .08 .11 20.73 .00 100.00 0.00 .00

131 Daggets Cr 1.97 .27 .33 1.70 .00 .00 100.00 .20

132 Van Dyne Cr 2.22 .21 .26 8.70 44.00 17.00 39.00 .05

133 Trib 1 West Branch Fond 

Du Lac

2.43 .26 .32 .87 .00 .00 100.00 .18

134 Mill Cr 2.33 .15 .18 4.32 .00 54.17 45.83 .03

135 Kankapot Cr 2.18 .17 .23 2.57 37.00 17.00 46.00 .04

136 Molash 4.02 .72 .87 .92 .00 .00 100.00 .14

137 Grimms 1.39 .27 .32 2.00 1.94 .00 98.06 .06

138 Pine Cr – Newton 2.90 .33 .40 3.41 4.50 .00 95.50 .07

139 Point Cr 6.24 .30 .36 2.59 8.97 11.03 80.00 .03

140 Pigeon 3.21 .26 .31 1.50 3.73 2.24 94.03 .06

141 Otter Cr – Plymouth 4.80 .20 .25 2.50 .00 6.31 93.69 .01

142 Weedens 3.63 .27 .35 6.80 13.08 16.82 70.09 .01

143 Kettle Moraine 3.58 .26 .29 4.60 18.54 13.25 68.21 .02

144 West Branch Milwaukee 3.17 .48 .63 6.89 .00 .00 100.00 .46

145 Parnell 3.21 .17 .21 5.70 6.03 38.79 55.17 .01

146 East Branch Milwaukee 7.06 .34 .45 .93 13.15 .00 86.85 .11

147 Crooked 5.07 .27 .37 1.09 .00 .00 100.00 .22

148 Wallace 4.22 .39 .47 3.01 29.79 9.93 60.28 .07

149 Hanneman 3.98 .23 .29 3.35 .00 2.88 97.12 .02

150 Mayfield Cr 3.77 .30 .35 6.80 14.29 19.05 66.67 .02

151 Friedens 3.75 .22 .28 9.83 17.14 50.00 32.86 .01
Appendixes 117

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

30.99 4.11 2.63 86.09 4.82 4.35 19.38 62.79 8.59 20.00

61.09 2.58 2.55 99.87 4.64 16.04 19.66 13.85 4.53 10.17

64.79 3.33 .57 97.89 1.30 1.07 16.43 38.67 9.84 9.42

27.86 23.28 13.13 66.56 3.46 .26 5.47 35.16 15.52 12.21

32.08 52.08 .42 100.00 .42 14.38 3.35 .00 27.92 20.00

32.97 32.21 1.69 90.78 .00 3.07 26.95 28.41 3.07 .11

37.42 31.15 8.52 80.49 .00 .00 1.50 78.85 17.34 11.79

12.92 6.95 31.12 25.00 15.03 .03 8.95 17.40 20.89 6.08

7.60 70.00 6.92 82.12 .00 .00 .00 67.02 39.42 6.27

4.58 31.25 48.54 33.75 7.29 7.08 .00 66.77 28.75 17.21

11.67 23.75 17.08 41.98 .00 .00 17.00 93.65 39.79 5.04

11.82 25.80 46.70 36.59 .00 .00 .56 71.48 33.86 20.00

7.45 35.57 34.51 42.58 1.46 .00 1.66 88.91 22.34 6.40

28.44 29.69 25.10 66.56 .63 15.73 6.61 6.04 10.00 20.00

21.98 25.83 13.54 54.38 3.33 1.35 3.13 87.29 11.04 15.79

12.08 .05 .05 99.82 .83 .00 36.82 24.24 2.81 5.84

5.83 5.60 24.74 9.79 3.15 .78 .00 72.76 13.23 17.65

51.49 7.95 1.91 96.67 .00 1.15 4.81 71.53 13.26 15.75

25.97 16.32 18.75 63.65 32.74 1.91 10.05 29.51 17.15 17.96

49.35 7.86 1.85 94.74 11.69 7.06 9.97 39.35 10.78 7.44

8.39 31.41 29.77 34.11 1.09 .00 .42 70.00 26.15 19.55

3.91 23.49 24.24 44.01 6.67 .00 3.20 81.67 45.10 19.32

17.50 58.13 .00 100.00 .00 3.85 14.41 18.96 5.00 20.00

23.13 37.92 10.42 80.21 .42 .00 37.26 22.71 6.04 17.58

42.71 21.98 18.75 70.31 12.71 .00 9.96 8.23 11.04 19.54

20.63 27.29 17.92 62.19 34.38 .00 4.46 22.29 9.58 18.33

51.07 15.63 15.80 76.61 10.98 37.86 19.46 .00 5.00 4.75

17.12 28.85 35.77 43.56 5.38 34.13 1.97 .00 1.92 7.23

6.35 28.13 34.38 28.96 53.75 .00 1.67 32.40 36.25 20.00

13.33 37.29 21.25 50.42 22.50 19.27 7.63 2.92 8.96 19.67

95.63 .21 .00 100.00 30.21 23.75 14.17 .00 4.79 20.00

8.85 18.13 24.17 24.90 16.15 2.50 .00 10.83 41.04 6.56

35.94 34.06 9.90 83.23 .00 .00 2.86 61.35 51.67 10.00

59.09 7.95 9.55 89.09 .00 3.98 1.59 70.91 12.50 19.41

22.81 34.58 18.85 63.65 .83 .00 19.30 66.56 29.58 19.50

17.92 39.38 27.81 51.98 10.00 2.71 1.30 36.35 17.08 17.63

15.00 22.40 26.56 44.38 30.42 .00 9.59 75.00 41.25 19.79

1.77 6.35 27.71 15.10 1.46 .00 6.74 90.52 14.38 9.58
118 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

152 Pigeon Cr – Theinsville 3.30 0.18 0.23 1.38 19.61 29.41 50.98 0.01

153 Willow Cr – Germantown 2.75 .21 .29 5.09 .00 .00 100.00 .15

154 Little Menomonee 4.12 .32 .40 .51 .00 .00 100.00 .02

155 Husher 4.54 .35 .42 2.51 .00 .00 100.00 .05

156 North Branch Pike 2.96 .45 .51 .82 .00 .00 100.00 .10

157 Willow Cr – Waupun 2.60 .42 .51 .87 .00 .00 100.00 .29

158 Flynn 4.25 .16 .23 6.22 17.69 60.77 21.54 .01

201 Galena 17.76 .43 .54 1.25 .00 31.88 68.13 .00

202 Skinner Cr – Klondyke 7.00 .51 .71 .70 .00 6.49 93.51 .13

203 East Branch Pecatonica 16.30 1.00 1.27 .52 .00 .00 100.00 .33

204 Little Sugar 6.60 .56 .70 1.32 .00 20.35 79.65 .05

205 West Branch Sugar – #1 5.25 .76 .85 .34 .00 .00 100.00 .23

206 Platte – Rockville 16.84 .66 .92 3.30 17.02 25.96 57.02 .03

207 Pigeon 5.95 .42 .58 3.05 14.47 16.23 69.30 .05

208 Rattlesnake 11.81 .41 .49 3.36 1.63 15.12 83.26 .01

209 Blake 7.86 .42 .60 2.20 10.25 8.13 81.63 .06

210 Fennimore 5.23 .44 .54 11.30 16.30 12.77 70.92 .07

211 Black Earth 1 13.02 .60 .69 .95 1.58 4.75 93.67 .07

212 Kickapoo 13.97 .62 .89 .61 .00 .00 100.00 .21

213 Moore 8.00 .29 .42 1.87 3.85 18.38 77.78 .04

214 Coon Cr 12.19 .58 .76 .98 .00 6.46 93.54 .46

215 Little La Crosse – Sparta 8.47 .47 .65 .94 .00 .00 100.00 .15

216 Lacrosse 14.45 .92 1.15 .71 .00 2.79 97.21 .14

217 Eau Galle 2 8.92 .33 .44 2.32 15.10 63.27 21.63 .02

218 Willow 18.51 .70 1.01 2.84 .00 11.08 88.92 .01

219 Wood 11.09 .62 .94 .49 .00 .00 100.00 .74

220 Yellow – Barron 20.74 .52 .66 1.65 9.88 28.50 61.63 .02

221 Hay River 27.03 .67 1.02 .67 .00 .00 100.00 .13

222 North Fork Eau Claire 12.07 .36 .51 1.96 12.42 10.00 77.58 .01

223 Big Eau Pleine 28.08 .70 .86 .96 6.88 9.00 84.13 .02

224 Black 56.27 .62 .78 1.55 1.15 5.13 93.72 .01

225 Yellow – Babcock 18.04 .85 1.21 .19 .00 .00 100.00 .17

226 Little Yellow 9.94 .60 .91 .31 .00 .00 100.00 .89

227 South Branch Yellow 8.68 .24 .37 .31 4.01 .00 95.99 .27

228 Ten Mile Cr 10.44 .61 .97 2.67 .85 .00 99.15 .21

229 Little Plover 5.74 .30 .40 2.55 .00 1.63 98.37 .09

230 Tomorrow 9.08 .54 .69 1.07 .00 5.13 94.87 .07

231 Pensaukee – Krakow 10.56 .35 .43 -- .00 3.13 96.88 .03
Appendixes 119

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

3.65 15.63 49.58 23.54 4.17 0.00 8.42 84.90 13.96 20.00

40.63 23.65 7.60 91.15 .00 .00 4.40 60.21 30.42 18.33

22.40 25.58 19.13 61.06 5.19 3.46 1.59 67.31 15.38 10.00

22.92 23.13 18.75 70.83 .00 .00 6.56 82.08 40.42 20.00

17.89 14.41 17.43 70.00 1.64 1.23 6.86 50.93 22.45 13.55

76.90 .00 .00 100.00 .00 5.36 25.62 .00 2.03 19.13

3.98 12.84 41.93 14.20 5.00 .23 .00 60.80 10.00 20.00

3.63 6.63 30.81 16.31 48.38 .00 2.55 21.44 16.00 10.53

25.52 1.35 14.58 82.50 .63 .00 7.37 61.77 44.58 13.83

19.25 53.25 11.50 80.67 .00 .00 7.23 21.67 36.83 20.00

11.04 15.94 23.33 33.02 9.58 .00 3.98 68.44 23.96 14.21

76.88 11.67 .00 98.54 .00 .00 7.87 29.90 17.71 2.63

19.87 13.62 35.53 35.13 1.18 6.51 5.84 15.26 11.32 15.55

29.42 21.54 13.65 59.81 13.94 21.35 1.87 .58 34.23 .00

23.57 6.34 23.75 38.48 16.88 14.91 2.66 26.43 12.50 .71

28.54 30.21 19.58 69.90 19.38 16.67 .57 .21 38.54 .00

64.50 4.00 21.50 78.17 1.67 4.42 1.15 .00 24.00 .00

17.88 13.56 50.63 37.75 3.88 16.69 21.65 35.56 17.38 10.80

.97 81.16 11.59 84.19 .00 2.72 6.21 23.88 29.63 16.00

1.54 55.87 28.94 61.83 .96 .19 1.76 65.77 65.38 10.27

8.69 68.00 3.13 87.06 .00 .00 4.83 33.69 25.88 12.75

.63 88.23 10.94 77.50 .00 1.25 12.64 .83 17.71 16.63

.13 65.44 19.13 64.94 .00 2.13 14.11 49.88 21.38 11.35

2.08 17.08 33.85 16.88 11.46 4.79 7.23 22.81 8.33 19.00

.00 19.13 28.00 15.81 9.13 1.75 7.65 18.19 11.78 20.00

.31 99.56 .00 100.00 .50 .88 15.25 5.69 13.88 20.00

.38 6.56 32.19 19.00 8.75 14.63 21.73 21.88 11.38 15.63

.00 90.37 8.90 82.65 .44 .00 2.70 14.63 38.97 20.00

.00 25.52 40.52 12.50 .00 .00 3.02 11.46 15.63 .00

.19 18.19 35.06 19.25 .00 .00 13.75 8.00 12.00 19.05

.94 21.88 20.75 34.75 10.50 .00 21.30 4.94 23.50 18.58

.63 83.33 3.96 89.79 .00 .00 25.89 58.33 37.71 20.00

1.88 97.50 .00 100.00 .00 .00 13.32 63.44 65.00 20.00

1.88 92.29 .00 100.00 .00 .00 11.23 47.29 52.29 19.83

.10 93.02 .73 98.96 .00 .00 19.75 38.02 11.04 15.71

.83 85.73 .00 96.04 1.88 6.35 11.88 53.23 .00 20.00

10.19 54.25 12.94 70.31 .31 7.06 24.68 42.69 2.25 19.55

11.98 27.81 42.29 38.23 21.04 1.98 .96 45.63 16.88 17.94
120 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

232 Pensaukee – Pensaukee 13.40 0.73 0.97 0.97 19.33 0.00 80.67 0.13

233 Middle Branch Embarrass 16.24 .39 .48 .99 .00 14.41 85.59 .04

234 Eau Claire – Kelly 27.24 .60 .88 1.00 24.70 47.12 28.18 .02

235 Eau Claire – Antigo 19.16 .58 .72 .86 .00 11.62 88.38 .03

236 Spring Brook 2 6.07 .19 .26 1.49 13.86 5.94 80.20 .06

237 Prairie 22.86 .41 .54 1.35 .00 .00 100.00 .03

238 Skinner 9.72 .56 .66 2.19 30.25 .00 69.75 .04

239 Spirit 18.06 .51 .63 1.46 .00 10.94 89.06 .03

240 North Fork Copper 9.18 .45 .56 .87 22.50 .00 77.50 .04

241 Hunting 18.80 .27 .42 1.96 .00 27.78 72.22 .03

242 Wolf River 55.12 .61 .82 1.17 .00 11.52 88.48 .02

243 North Branch Pike 11.35 .83 .97 .50 6.77 .00 93.23 .10

244 Popple 22.97 .85 1.01 1.26 22.88 .00 77.13 .04

245 Woods 9.82 .22 .28 3.03 .00 11.27 88.73 .02

246 Pine 35.80 .51 .68 1.05 3.75 6.50 89.75 .01

247 Brule 31.58 .55 .81 1.77 2.75 20.38 76.88 .00

248 Kaubashine 7.71 .17 .23 .44 .00 20.18 79.82 .21

249 Namekagon 27.91 .38 .59 2.52 1.88 31.88 66.25 .02

250 Totagatic 10.89 .32 .54 .92 8.33 3.66 88.01 .20

251 Eau Claire 17.12 .41 .57 1.32 6.60 28.47 64.93 .05

252 Upper Ox 7.70 .35 .59 .89 23.97 .00 76.03 .19

253 North Fish Cr 11.48 .47 .72 .86 4.43 15.44 80.13 .11

254 Bois Brule 19.85 .57 .74 2.67 .00 43.66 56.34 .02

255 Amnicon 8.31 .35 .58 .29 16.27 .00 83.73 .13

256 Upper Tamarack 17.31 .48 .59 1.11 4.76 13.69 81.55 .02

257 Turtle Cr 2 28.63 .38 .52 1.21 .00 17.38 82.63 .03

258 Whitewater Cr 12.49 .43 .49 .98 .00 .00 100.00 .04

259 Token Cr 9.25 .44 .63 .61 .00 .00 100.00 .26

260 Yahara 5.86 .39 .47 1.06 .00 .00 100.00 .06

261 Oconomowoc 10.59 .35 .50 1.30 7.53 .00 92.47 .16

262 Milwaukee 51.87 .42 .60 1.75 .00 40.00 60.00 .01

263 Cedar Cr 21.64 .36 .47 .56 2.72 8.31 88.97 .03

264 Sauk 2.72 .26 .30 .77 -- -- -- .02

265 Stoney 4.64 .28 .35 9.24 5.56 9.44 85.00 .08

266 North Branch Milwaukee 12.01 .39 .51 .18 .00 8.30 91.70 .12

267 West Branch Rock 17.39 .48 .65 .03 16.94 21.67 61.39 .03

268 Onion 16.09 .22 .34 4.45 .00 56.96 43.04 .01

269 South Branch Sheboygan 4.91 .26 .32 5.39 20.41 40.31 39.29 .00
Appendixes 121

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

12.06 56.88 8.06 80.19 0.00 0.00 7.90 39.50 33.25 20.00

2.11 40.39 41.05 45.72 .00 .00 15.35 19.01 3.55 10.26

.00 21.72 30.94 28.44 .63 .00 11.13 24.38 22.34 12.66

.00 28.38 36.56 13.94 4.06 .31 1.63 27.81 9.13 18.25

4.90 52.71 25.10 72.71 .00 1.04 3.99 49.79 2.29 19.71

2.31 25.50 44.56 17.56 .13 10.19 13.00 17.50 12.63 19.63

28.54 16.67 18.75 48.56 .00 .83 16.79 32.02 4.42 10.00

3.88 23.38 29.63 25.06 1.13 15.38 22.58 14.44 8.75 19.78

17.88 32.50 27.88 56.35 .00 1.25 5.67 32.12 28.85 10.00

11.15 20.19 35.58 37.69 .00 3.27 20.73 34.13 2.69 10.00

1.69 22.50 33.31 25.00 .25 6.50 12.77 1.81 7.25 16.50

5.58 73.56 12.98 72.02 .00 1.54 28.23 33.37 4.23 9.62

12.94 45.50 24.75 55.81 .00 .06 11.51 .00 6.00 19.38

4.04 10.77 66.15 11.06 .00 4.71 9.84 30.77 10.38 10.00

2.00 11.63 58.00 7.88 .13 .06 3.86 2.69 11.13 20.00

.00 5.75 37.31 10.44 2.63 .00 15.04 4.19 5.88 19.25

27.19 27.92 16.88 72.92 .00 12.81 2.78 24.38 6.88 10.00

4.81 25.06 25.00 24.25 .75 1.31 6.50 12.44 .75 19.63

3.65 84.42 7.50 87.12 .00 3.37 10.75 32.46 35.38 9.65

5.52 44.90 27.40 53.85 .00 6.35 .55 9.17 .42 8.79

14.20 85.11 .68 97.73 .00 31.70 4.19 .34 .00 10.00

.13 71.00 15.75 64.31 1.00 .00 8.47 11.81 25.00 20.00

1.50 27.19 38.81 33.31 .00 1.19 20.45 23.44 3.88 20.00

35.00 46.63 4.52 87.31 .77 34.33 18.47 2.02 13.27 10.00

2.79 24.71 42.31 22.88 1.54 6.63 16.89 11.63 12.12 9.85

1.81 51.88 26.75 28.91 18.19 8.69 10.54 7.44 23.38 20.00

12.50 55.38 20.63 63.00 21.13 50.63 65.52 10.75 6.63 20.00

33.64 51.48 8.30 85.11 .91 7.61 4.89 39.55 2.73 20.00

2.83 75.00 12.50 64.17 4.50 18.75 13.78 16.58 11.50 1.30

47.19 28.23 5.42 87.19 .10 1.56 1.83 11.98 .63 9.63

.38 11.25 27.69 8.63 2.19 31.44 12.17 4.00 3.00 15.48

6.18 26.91 38.09 31.71 .00 .86 4.34 52.43 20.79 12.82

7.98 31.83 34.90 41.92 19.23 .19 .77 .00 37.31 13.04

13.75 55.42 18.02 62.50 .00 .00 .00 40.94 21.25 20.00

42.13 24.81 18.94 70.50 .00 3.06 9.62 19.88 5.88 20.00

15.92 6.33 19.00 28.42 5.00 .00 16.27 45.33 18.00 9.53

2.50 9.69 19.94 18.25 24.00 .25 10.08 36.88 10.63 11.10

.21 12.40 20.21 11.25 40.83 .00 14.84 13.96 3.75 20.00
122 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 2. Physical-habitat characteristics of each of the 240 studied wadeable streams in Wisconsin—Continued. All data 

collected by the Wisconsin Department of Natural Resources. 

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number; m/km, meter per kilometer; m, meter; --, no data collected at site]

ID

(see 

fig. 4)

Stream name

Stream 

width 

(m)

Stream 

mean 

depth

(m)

Mean 

thalweg 

depth

(m)

Stream 

gradient 

(m/km)

Percent 

pools

Percent 

riffle

Percent 

run

Depth of 

sediment on 

stream bottom 

(m)

270 Meeme 4.25 .21 .27 2.80 0.00 37.86 62.14 0.01

271 Silver Cr 4.41 .51 .59 3.08 24.14 .00 75.86 .02

272 South Branch Manitowoc 18.47 .38 .46 .51 .00 7.86 92.14 .02

273 Manitowoc 27.93 .44 .64 1.12 16.42 28.64 54.94 .01

274 East Twin 12.96 .36 .45 1.30 6.74 20.43 72.83 .02

275 Neshota 5.03 .13 .17 1.11 18.30 12.50 69.20 .04

276 Kewaunee 16.44 .36 .47 .86 .00 30.44 69.56 .01

277 East 6.35 .44 .55 .68 53.36 .00 46.64 .16

278 Duck Cr 10.80 .27 .35 2.19 13.51 25.33 61.16 .01

301 Vismal Cr -- -- -- -- -- -- -- --

302 Levis Cr -- -- -- -- -- -- -- --

303 Ditch #6 South Branch Ten 

Mile Cr

-- -- -- -- -- -- -- --

304 South Branch Suamico -- -- -- -- -- -- -- --

305 West Branch Red -- -- -- -- -- -- -- --
Appendixes 123

Percent 

silt

Percent 

sand

Percent 

gravel

Percent rockysubstrate 

embeddedness

Percent stream 

bottom covered 

by algae

Percent 

macrophytes

Percent 

cover

Percent 

stream 

shaded

Percent 

streambank 

with erosion

Buffer 

width

(m)

5.94 22.29 53.44 26.04 5.00 1.56 8.57 24.06 12.29 8.92

4.42 22.88 37.50 26.54 37.40 4.04 5.88 .38 1.54 6.92

6.50 16.19 42.06 26.75 .00 .00 14.72 26.88 12.25 13.88

1.00 11.06 35.19 12.06 .38 .00 11.71 8.94 14.13 20.00

7.38 21.56 45.63 24.50 .00 .00 1.85 61.00 7.88 9.85

11.70 26.07 40.98 41.88 1.79 .00 .00 65.18 56.61 10.00

5.31 11.80 27.19 21.72 10.16 .00 5.88 9.06 1.41 14.97

16.50 45.00 5.75 91.00 .00 .00 7.18 77.00 59.50 15.97

.25 12.81 28.88 15.94 .13 .00 8.71 26.50 8.00 16.83

-- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- --
124 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 3. Diatom nutrient-tolerance ranking for individual diatom taxa. Taxa without nutrient-tolerance values are not 

included in the table. 

[nutrient-tolerance ranking: 1, oligotrophic; 2, oligo-mesotrophic; 3, mesotrophic; 4, meso-eutrophic; 5, eutrophic; 6, hypereutrophic; var, variety]

Diatom taxa Nutrient-tolerance 

ranking

Achnanthidium exiguum 2

Achnanthidium hungaricum 6

Achnanthidium minutissimum 2

Amphipleura pellucida 2

Amphora ovalis 5

Amphora ovalis var. affinis 5

Amphora ovalis var. pediculus 5

Amphora perpusilla 5

Amphora veneta 5

Aulacoseira granulata 5

Aulacoseira italica 3

Brachysira brachysira 1

Caloneis bacillum 4

Cocconeis pediculus 5

Cocconeis placentula var. euglypta 5

Cocconeis placentula var. lineata 5

Cocconeis placentula var. placentula 5

Craticula accomoda 1

Craticula buderi 3

Craticula cuspidata 3

Cyclostephanodiscus species 5

Cyclotella atomus 1

Cyclotella radiosa 1

Cymbella affinis 5

Cymbella naviculiformis 2

Cymbella tumida 2

Cymbella tumidula 3

Diatoma vulgare 1

Discotella stelligera 1

Encyonema minutum 5

Encyonema silesiacum 3

Eolimna minima 3

Eolimna subminuscula 5

Epithemia adnata 3

Epithemia sorex 5

Epithemia species 5

Epithemia turgida 5

Eunotia formica 5

Eunotia incisa 5

Diatom taxa Nutrient-tolerance 

ranking

Eunotia naegelii 4

Eunotia pectinalis var. undulata 5

Eunotia sudetica 2

Fallacia pygmaea 5

Fistulifera pelliculosa 2

Fragilaria capucina (several var.) 3

Fragilaria crotonensis 2

Fragilaria vaucheriae 3

Frustulia rhomboides 4

Frustulia saxonica 1

Frustulia vulgaris 4

Geissleria decussis 4

Gomphoneis minutum 1

Gomphoneis olivacea 2

Gomphonema acuminatum 2

Gomphonema acuminatum var. pusilla 2

Gomphonema affine 3

Gomphonema apuncto 1

Gomphonema gracile 1

Gomphonema parvulum 2

Gomphonema truncatum 4

Gyrosigma attenuatum 5

Gyrosigma spencerii 5

Hippodonta capitata 1

Melosira varians 1

Meridion circulare 3

Navicula angusta 2

Navicula antonii 5

Navicula arvensis 4

Navicula capitatoradiata 5

Navicula gottlandica 5

Navicula gregaria 5

Navicula lanceolata 5

Navicula minuscula 4

Navicula radiosa 4

Navicula rostellata 5

Navicula tenelloides 5

Navicula tripunctata 5

Navicula trivialis 5
Appendixes 125

Diatom taxa Nutrient-tolerance 

ranking

Navicula veneta 5

Navicula viridula 5

Nitzschia acicularis 5

Nitzschia amphibia 5

Nitzschia capitellata 6

Nitzschia dissipata 4

Nitzschia fonticola 4

Nitzschia frustulum 5

Nitzschia gracilis 3

Nitzschia inconspicua 5

Nitzschia linearis 4

Nitzschia nana 3

Nitzschia palea 6

Nitzschia paleacea 5

Nitzschia pusilla 4

Parlibellus protracta 5

Placoneis exigua var. capitata 4

Planothidium dubium 5

Planothidium lanceolatum 5

Psammothidium subatomoides 2

Reimeria sinuata 3

Rhoicosphenia curvata 5

Rhopalodia gibba 5

Rossithidium linearis 1

Sellaphora pupula 4

Sellaphora rectangularis 4

Sellaphora seminulum 5

Stauroneis anceps 4

Staurosira construens 4

Staurosira construens var. binodis 6

Staurosira construens var. venter 4

Staurosira elliptica 5

Staurosirella leptostauron 4

Staurosirella leptostauron var. dubia 4

Staurosirella pinnata 4

Staurosirella pinnata var. intercedens 5

Stenopterobia delicatissima 1

Stephanocyclus meneghiana 4

Surirella angusta 5

Diatom taxa Nutrient-tolerance 

ranking

Surirella linearis 2

Synedra delicatissima 3

Synedra filiformis var. exilis 2

Synedra parasitica 4

Synedra rumpens 2

Synedra rumpens var. familiaris 2

Synedra ulna var. amphirhynchus 5

Synedra ulna var. contracta 3

Tabellaria fenestrata 2

Tabellaria flocculosa 3

Tabellaria flocculosa strain IV 3

Tabularia fasciculata 5

Thalassiosira weissflogii 6

Appendix 3. Diatom nutrient-tolerance ranking for individual diatom taxa. Taxa without nutrient-tolerance values are not 

included in the table—Continued. 

[nutrient ranking: 1, oligotrophic; 2, oligo-mesotrophic; 3, mesotrophic; 4, meso-eutrophic; 5, eutrophic; 6, hypereutrophic; var, variety]
126 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin. All data collected by the Wisconsin 

Department of Natural Resources.

[CR, Creek; TRIB, Tributary; BR, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

1 Onion -- 4.38 15.10 35.86 2.19 59.69 34.29 1.53

2 Thompson 155 5.16 67.93 22.76 3.46 66.40 37.93 .00

3 Parker 355 3.43 21.80 38.66 3.87 53.85 55.88 23.08

4 Catlin 31 3.98 27.50 32.68 2.07 75.37 55.56 14.18

5 Leo 54 3.47 14.00 43.02 1.84 68.61 38.46 6.73

6 Lower Ox 64 4.10 27.25 32.00 2.47 73.13 74.29 41.85

7 Lord 165 2.14 4.20 92.25 2.07 77.56 57.58 25.64

8 Fivemile 256 2.07 5.25 85.20 4.26 90.00 63.89 5.91

9 Cap -- -- -- -- 4.36 59.20 45.45 16.42

10 Spring Cr 654 3.69 9.20 48.09 4.42 53.79 44.00 35.61

11 Mosquito Br 227 4.34 9.04 44.29 2.18 74.32 56.25 9.29

12 Smith Lake 22 3.76 44.83 31.67 7.15 10.22 12.12 6.57

13 Fiddler 189 3.54 10.10 47.52 4.24 49.37 44.83 34.81

14 Spring Lake -- 2.82 13.40 50.54 5.95 32.61 25.93 1.45

15 Rainbow -- 3.01 18.80 44.15 5.42 50.72 32.20 6.52

16 Dody Brook 16 3.38 15.20 42.74 3.08 77.47 40.00 37.36

17 Swan 2,544 1.75 21.31 58.66 3.63 90.09 72.41 7.76

18 Becky 569 2.38 11.80 59.21 2.36 71.15 66.67 13.46

19 Hay 228 4.47 16.67 34.22 6.22 29.37 16.67 3.97

20 Soft Maple 446 4.29 58.33 27.27 3.57 70.18 52.83 15.54

21 Mcdermott 929 3.36 29.60 37.07 5.22 89.50 45.45 4.50

22 Meadow Cr -- -- -- -- 6.16 6.58 10.00 2.63

23 Gilbert Cr -- -- -- -- 4.64 11.24 24.14 62.13

24 Trib 1 Shoulder Cr -- -- -- -- 7.57 4.27 2.78 5.49

25 Crazy Horse Cr -- -- -- -- 4.93 22.29 10.00 2.29

26 Alder Cr -- -- -- -- 5.67 29.80 13.51 1.32

27 Sailor Cr -- -- -- -- 2.44 70.11 54.55 21.26

28 Knuteson 737 1.84 3.25 100.00 3.28 59.75 48.65 55.08

29 South Fork Hemlock 87 4.78 8.50 43.39 3.32 75.36 61.11 8.70

30 Little Soft Maple 2,197 2.07 20.60 58.96 2.28 71.23 58.00 20.89

31 Alvin 239 3.05 11.05 50.67 2.62 75.91 66.67 27.74

32 North Otter 23,122 4.01 22.50 34.00 2.21 59.24 50.00 32.35

33 North Fork Thunder 80 4.53 2.60 72.84 .84 86.59 66.67 11.59

34 Waupee 318 3.14 7.47 57.72 4.92 53.59 21.43 .00

35 Trout -- -- -- -- 4.42 49.37 29.63 23.63

36 South Fork Popple -- -- -- -- 7.64 6.54 5.26 14.95

37 Mosquito Cr 76 2.43 9.70 61.55 6.55 36.56 30.43 .54

38 Hay Meadow 977 3.14 15.32 45.00 5.46 47.92 36.96 3.65
Appendixes 127

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.51 35.00 80.00 77.61 22.39 0.00 23.13 0.00 89 9

.00 29.00 90.00 68.35 29.11 .00 86.08 2.53 55 6

1.40 34.00 45.00 40.30 21.39 6.47 12.44 38.81 96 16

.00 27.00 90.00 97.87 2.13 .00 97.87 2.13 45 2

.00 26.00 60.00 11.24 48.31 5.62 12.36 20.22 82 11

.00 35.00 42.00 1.43 67.91 6.24 1.96 30.48 130 15

.00 33.00 20.00 .00 39.87 21.52 .00 51.27 95 9

.91 36.00 15.00 1.67 20.00 1.67 .83 85.00 83 10

.00 44.00 20.00 .00 37.18 7.69 1.28 66.67 53 8

.00 25.00 25.00 1.67 83.33 .00 .00 77.50 106 6

.00 32.00 90.00 89.83 10.17 .00 81.36 .00 55 4

.73 33.00 30.00 20.00 71.43 8.57 .00 80.00 95 4

.00 29.00 50.00 7.89 81.58 2.63 44.74 23.68 34 8

4.35 27.00 30.00 2.88 58.27 17.99 12.95 48.20 93 10

3.14 59.00 80.00 58.04 28.57 2.68 78.57 9.82 75 8

.00 25.00 21.00 .00 46.94 19.97 .58 50.73 457 10

.00 29.00 50.00 30.63 21.35 17.63 35.50 50.81 291 16

.00 36.00 60.00 34.07 24.73 7.14 53.85 32.97 182 9

.79 24.00 30.00 .00 43.00 7.00 2.00 48.00 97 10

.00 53.00 32.00 1.08 31.89 18.38 2.70 65.41 66 12

.00 22.00 25.00 2.31 31.02 10.42 8.33 61.34 281 10

4.61 30.00 35.00 .00 66.19 1.64 .00 48.16 128 8

.00 29.00 40.00 .00 55.01 1.16 4.67 45.31 237 13

18.90 36.00 30.00 .00 80.24 3.12 3.43 52.92 214 13

14.86 30.00 32.00 .00 60.58 3.01 2.15 12.67 233 10

.00 37.00 35.00 .00 46.07 8.86 1.30 30.09 192 13

.00 33.00 17.00 .00 22.65 1.91 .96 70.55 157 13

.00 37.00 55.00 19.32 47.16 18.18 15.34 34.66 62 16

.00 36.00 70.00 73.38 4.32 3.60 58.99 22.30 97 12

.68 50.00 40.00 7.01 10.83 5.73 7.01 76.43 157 11

1.46 33.00 50.00 17.07 18.29 .00 31.71 65.85 78 7

.00 36.00 60.00 64.48 1.64 .00 64.48 33.33 130 5

.00 33.00 90.00 70.00 27.50 .00 67.50 2.50 25 7

.00 42.00 40.00 1.39 75.00 6.94 1.39 37.50 45 9

.00 27.00 32.00 .00 49.17 5.48 4.24 52.38 414 14

4.05 38.00 30.00 .00 56.65 7.98 1.60 42.29 63 12

2.69 46.00 40.00 20.69 75.86 .00 20.69 13.79 20 9

1.56 46.00 40.00 1.59 82.17 3.82 10.83 21.34 285 12
128 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

39 Cedar Springs 3,419 1.94 10.46 67.65 5.98 32.62 37.93 0.53

40 Skunk Cr 505 2.96 10.61 52.41 5.76 65.54 36.00 7.43

41 Jennie 315 2.78 14.02 50.41 3.90 69.73 45.65 24.04

42 Trout 449 3.01 7.71 58.39 4.90 27.03 37.14 17.57

43 Muskellunge – 

Heafford Junction

-- 2.61 27.37 46.45 7.41 7.35 20.83 .74

45 Johnson 347 2.01 12.94 64.27 5.35 28.83 28.26 9.82

46 Threemile 293 2.99 65.46 37.37 7.82 2.63 15.79 .00

47 Raeder Cr 19 4.37 48.21 27.48 4.06 47.26 51.61 23.29

48 Hamann Cr 117 3.13 42.39 37.37 4.45 62.94 34.29 26.40

49 East Fork Hamann -- -- -- -- 4.75 24.83 27.27 46.21

50 Hamann Trib 11 4.31 55.66 27.35 4.61 47.37 40.48 30.70

51 Widow Green 1,629 3.81 49.17 30.93 4.33 25.50 45.83 61.92

52 North Fork Willow 196 4.11 69.21 27.85 6.91 44.33 17.14 .99

53 Black Brook 553 3.63 54.42 31.92 4.88 44.98 33.33 14.83

54 South Fork Willow 470 4.28 64.88 27.04 5.67 11.43 15.63 1.14

55 Hutton Cr 1,222 4.63 33.10 27.94 4.91 40.00 20.83 5.45

56 Tenmile Cr 1,029 4.52 27.89 29.52 3.13 58.27 52.17 33.09

57 Cr 12–13 2,000 3.85 72.33 29.41 4.26 52.17 53.33 2.54

58 Running Valley 16,672 4.09 76.94 27.71 7.53 5.33 8.00 .59

59 Cr 1–8 -- 3.84 51.60 30.52 7.47 7.97 26.09 .00

60 Cr 1–12 -- 4.42 48.90 27.18 4.88 61.19 33.33 .00

61 18-mile 3,915 4.07 18.35 35.50 3.15 51.59 42.55 35.69

62 Cady 5,970 3.01 28.01 63.68 3.67 84.65 58.33 14.11

63 Eagle 8,368 3.82 71.79 42.88 4.34 39.95 34.38 34.80

64 Joos -- -- -- -- 4.28 42.52 41.94 36.92

65 Trout Run -- -- -- -- 2.51 68.63 36.36 .65

66 Bohris 3,924 4.40 60.19 39.54 3.27 47.92 52.94 50.52

67 South Branch Oneill Cr -- -- -- -- 6.87 23.67 15.63 10.06

68 Unnamed Trib 1 East Fork 

Black

7 2.98 5.54 68.10 3.71 73.19 52.00 30.43

69 Unnamed Trib 1 Rock Cr -- 3.88 47.60 30.56 5.52 61.83 18.52 10.22

70 Bloody Run -- 4.88 3.30 71.19 4.16 24.82 25.93 5.67

71 Beaver Cr -- -- -- -- 5.97 34.78 35.71 27.33

72 Tributary To Beaver Cr -- -- -- -- 4.66 54.55 44.00 42.42

73 North Fork Hemlock Cr -- -- -- -- 7.01 10.30 20.00 1.82

74 Mormon -- 3.97 62.88 42.50 4.35 34.73 38.71 37.25

75 Timber Coulee -- 3.46 28.13 57.65 3.62 34.75 43.75 24.82
Appendixes 129

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

2.67 29.00 0.00 7.14 71.43 7.14 0.00 92.86 14 4

.00 25.00 10.00 .00 85.37 4.88 2.44 92.68 26 5

.00 46.00 40.00 1.00 23.38 1.49 15.92 55.22 112 14

.68 35.00 60.00 46.43 14.29 10.71 57.14 42.86 25 5

.00 24.00 .00 9.52 47.62 28.57 9.52 47.62 10 7

1.23 46.00 45.00 2.47 74.38 5.56 4.01 24.07 145 11

.66 19.00 30.00 1.49 24.25 3.73 1.49 64.18 211 8

.00 31.00 30.00 .00 37.37 4.39 10.70 62.02 325 14

.00 35.00 37.00 .00 43.02 9.04 9.72 48.62 332 19

.00 22.00 45.00 .88 47.05 15.61 3.53 69.29 113 13

.44 42.00 42.00 .00 24.61 12.98 5.09 55.73 290 17

.00 24.00 .00 .00 22.22 29.63 .00 51.85 40 4

.00 35.00 25.00 .00 17.77 17.77 .00 18.18 224 7

.00 42.00 32.00 .00 42.17 3.21 1.61 58.63 189 13

.00 32.00 20.00 .00 38.46 5.77 2.88 59.62 87 12

1.21 48.00 40.00 .72 11.69 21.36 2.45 49.78 289 15

.00 23.00 22.00 .00 20.63 17.62 .00 57.23 342 13

.36 30.00 .00 53.33 46.67 .00 53.33 46.67 14 2

.00 25.00 50.00 9.63 52.75 7.80 19.27 37.16 182 10

.00 23.00 70.00 16.67 80.56 2.78 16.67 5.56 33 4

.00 24.00 .00 6.67 93.33 .00 6.67 .00 14 2

.00 47.00 .00 28.57 71.43 .00 28.57 28.57 13 4

.00 24.00 90.00 38.78 58.68 .00 93.03 2.53 426 6

.00 32.00 30.00 .00 52.56 38.46 .00 47.44 174 6

.00 31.00 15.00 .00 7.57 54.98 .00 81.67 234 9

.00 22.00 32.00 .86 57.76 39.66 1.72 45.69 113 9

.00 17.00 52.00 2.59 81.61 9.20 2.87 15.23 266 16

.00 32.00 40.00 .00 43.75 30.21 3.29 58.39 738 19

.00 25.00 30.00 1.96 26.96 28.92 .98 76.47 101 12

.00 27.00 50.00 .00 56.28 4.21 3.16 75.07 96 11

.00 27.00 100.00 66.07 28.57 1.79 87.50 3.57 51 7

.00 14.00 47.00 .00 44.26 19.78 7.65 62.92 333 20

.00 25.00 45.00 .00 46.86 13.51 7.89 64.20 224 17

8.48 30.00 37.00 .00 78.55 4.39 1.46 68.87 208 12

.00 31.00 20.00 1.63 33.70 54.08 .00 62.77 135 9

.00 32.00 60.00 65.23 28.30 6.47 20.49 6.47 206 5
130 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

76 Spring Coulee 19,863 3.42 67.49 47.54 3.62 45.43 37.50 19.29

77 Rush-02 16,047 4.13 43.51 44.80 3.81 52.82 39.29 30.26

78 Beaver 12,290 4.16 77.78 39.45 4.42 47.00 46.43 37.60

79 Dilly -- -- -- -- 4.55 53.91 39.39 32.35

80 Trib West Branch Baraboo 500 4.65 17.21 59.15 2.77 55.83 38.10 38.65

81 Crooked 2,690 3.47 69.41 46.70 3.40 60.89 41.67 9.68

82 Moore 7,423 4.07 77.19 40.22 4.05 49.74 37.93 56.92

83 Warner Br 730 3.97 73.25 41.36 3.78 17.00 37.84 59.65

84 Warner 93 4.35 37.62 45.00 2.42 68.46 52.63 36.91

85 Otter Cr – Lafarge 3,832 4.55 47.25 40.83 3.41 38.43 42.86 56.33

86 Harrison 9,024 3.78 72.64 43.18 4.20 48.57 50.00 36.00

87 Mccartney Br -- -- -- -- 4.76 65.36 32.14 22.88

88 Hackett Br 3,771 4.00 90.03 39.87 4.80 36.47 32.35 24.71

89 Kuenster 1,239 4.44 57.28 39.71 4.90 63.22 35.00 27.59

90 Muskellunge Cr – 

Beetown

21,785 4.14 79.05 39.43 5.56 22.22 14.29 9.66

91 Bull 10,157 3.46 68.83 46.87 5.97 14.12 13.04 20.00

92 Willow 25,755 4.07 82.41 39.80 4.59 25.39 27.27 26.94

93 Mounds Br -- -- -- -- 5.23 17.19 9.09 5.63

94 Young Br 3,094 3.88 79.57 41.68 5.37 68.51 33.33 18.78

95 Mcadam Br 5,905 4.02 84.19 40.01 5.02 61.79 23.26 12.62

96 Indian Cr – Dickeyville 12,262 4.14 68.52 40.44 7.21 12.43 40.00 .56

97 Kieler Cr 9,107 3.97 60.16 42.91 8.01 .00 .00 .00

98 Apple 3,446 4.93 13.79 64.88 4.34 7.03 27.78 85.41

99 Trib 1 French Spring Cr 3,537 4.28 59.74 40.48 5.01 8.44 16.67 53.90

100 Rowan 264 2.88 10.61 95.68 3.41 32.16 35.29 44.31

101 Hinkson -- -- -- -- 4.42 33.55 28.57 .66

102 North Branch Honey 3,915 3.97 78.58 40.92 5.54 28.88 29.41 1.07

103 Moen 7,491 4.43 47.68 41.58 4.01 35.37 51.85 30.61

104 Trout Cr – Barneveld 7,706 2.99 45.73 56.91 5.12 9.78 36.36 8.00

105 Lowery 11,216 3.16 64.61 51.15 3.81 29.91 35.00 14.53

106 Trib Otter Cr 6,954 4.59 73.90 36.66 4.29 52.60 35.29 30.96

107 Bear 5,507 4.60 74.31 36.59 4.71 41.35 36.11 3.76

108 Horse 1,517 3.80 78.88 42.47 3.87 38.27 55.00 52.35

109 Brush 4,598 3.47 52.79 49.03 4.14 49.45 37.50 39.34

110 East Mill 6,620 4.06 82.35 39.87 4.19 30.34 38.46 17.24

111 Trib 1 Dead Cr -- 5.41 85.67 31.20 9.08 .54 3.57 1.63

112 Johnson Cr – Farmington 1,077 4.15 75.16 39.69 4.41 13.83 13.33 .00

113 Calamus Cr 3,455 4.99 68.88 34.81 7.31 8.56 17.24 1.60
Appendixes 131

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.00 32.00 60.00 81.20 10.20 7.40 1.40 7.40 203 6

.00 28.00 50.00 43.59 31.41 .00 32.05 25.00 158 6

.00 28.00 30.00 .14 41.64 23.37 .00 41.78 636 12

.00 33.00 45.00 .00 75.58 8.43 8.72 22.97 297 11

.00 21.00 35.00 .57 85.63 2.30 77.01 13.79 166 8

.00 24.00 60.00 100.00 .00 .00 .00 .00 93 2

.00 29.00 40.00 1.26 51.13 24.69 .76 42.82 186 14

.00 37.00 30.00 .00 40.72 1.70 1.14 56.63 459 8

.00 19.00 30.00 .74 52.96 15.19 5.19 44.44 151 12

.00 28.00 30.00 1.07 57.22 13.37 2.14 37.70 163 11

.00 24.00 20.00 5.17 35.63 31.61 1.72 57.47 139 8

.00 28.00 10.00 .00 8.56 60.48 .00 63.12 228 9

.39 34.00 37.00 .00 72.88 .00 .00 13.87 476 9

.00 20.00 15.00 .11 32.17 50.88 .11 51.97 1004 14

.00 42.00 20.00 .32 42.07 42.03 .32 43.12 1483 14

.00 23.00 20.00 .07 26.33 48.94 .20 53.79 693 15

.00 33.00 30.00 .63 53.13 23.44 5.31 30.31 691 15

.00 33.00 40.00 .00 50.94 3.77 .00 32.48 294 11

.00 27.00 20.00 .34 21.13 15.35 .34 26.44 292 13

.33 43.00 45.00 .00 70.71 3.21 .00 4.58 391 13

.00 20.00 .00 -- -- -- -- -- -- 1

.00 8.00 30.00 .00 6.83 29.93 .00 31.51 432 9

.00 18.00 40.00 .00 25.10 14.82 .05 17.21 1336 15

1.30 30.00 65.00 .56 43.33 38.57 9.24 69.92 269 10

.00 17.00 50.00 11.25 83.25 5.50 83.00 5.50 308 4

.00 28.00 70.00 40.64 58.90 .00 84.02 14.61 187 5

.00 34.00 45.00 .40 64.94 6.37 52.59 22.71 246 11

.00 27.00 .00 4.35 78.26 .00 82.61 4.35 22 5

.00 22.00 70.00 25.79 69.68 4.52 70.14 4.52 143 5

.00 20.00 60.00 2.67 81.33 .00 45.33 16.00 60 4

.00 34.00 25.00 .37 36.48 38.21 1.74 58.44 405 13

.00 36.00 25.00 10.43 15.95 26.38 21.47 65.64 98 9

.00 20.00 35.00 .00 31.25 11.72 10.16 72.66 115 10

.00 24.00 80.00 64.75 22.13 8.20 77.05 15.57 111 9

.00 26.00 22.00 .64 11.92 19.65 .00 85.19 518 7

3.80 28.00 20.00 .00 96.83 3.17 .00 100.00 95 3

.00 15.00 40.00 .00 94.38 2.76 .00 89.47 263 8

2.14 29.00 12.00 .00 29.13 70.87 .00 98.70 193 9
132 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

114 Schultz Cr 2,907 4.72 8.50 89.24 4.68 7.60 25.00 43.27

115 Pratt Cr 24,862 3.76 17.43 65.69 6.01 34.36 36.36 18.40

116 Trib Pratt Cr -- -- -- -- 6.13 1.01 7.14 5.05

117 Casper Cr 8,196 4.26 50.33 42.22 5.50 .79 5.56 16.67

118 Scuppernong 252 3.27 9.71 94.51 6.20 36.97 31.82 1.82

119 Door Cr 1,115 4.74 35.42 43.28 4.52 53.88 28.57 19.40

120 Little Door Cr 279 2.86 19.67 73.77 5.66 7.14 31.25 1.95

121 Branch Mineral Point 4,924 4.12 69.95 40.45 4.57 13.38 27.59 61.20

122 Gill 1,909 4.47 51.45 40.51 4.10 13.08 57.14 38.46

123 Baker 855 4.54 28.79 47.86 5.85 27.67 31.82 32.08

124 Spring Brook 212 2.50 18.76 77.32 4.42 56.52 53.85 27.72

125 Ore 615 4.18 72.21 39.75 4.36 33.82 42.31 57.88

126 Bassett Cr 1,954 4.83 15.45 61.42 7.49 11.61 18.75 .65

127 West Branch Nippersink 559 4.55 49.51 40.36 4.87 49.68 29.63 2.55

128 White Cr 8,993 4.68 34.11 44.18 3.99 2.92 10.00 1.46

129 Pumpkinseed Cr -- -- -- -- 7.18 .00 .00 2.96

130 Spring Bk 3,613 4.61 52.81 39.36 5.71 .00 .00 4.14

131 Daggets Cr -- -- -- -- 7.81 4.14 7.14 .00

132 Van Dyne Cr -- -- -- -- 8.01 .00 .00 .00

133 Trib 1 West Branch Fond 

Du Lac

8,427 3.91 58.18 43.77 7.85 1.04 5.41 1.04

134 Mill Cr 3.97 30.46 51.21 4.28 21.29 40.00 17.42

135 Kankapot Cr 1,680 4.78 70.67 35.84 9.41 .74 12.50 .00

136 Molash 2,850 3.62 76.80 44.39 5.60 63.64 26.09 5.84

137 Grimms -- 4.20 26.07 52.16 7.99 .00 .00 .00

138 Pine Cr – Newton -- -- -- -- 5.81 48.67 37.50 16.67

139 Point Cr -- -- -- -- 5.22 22.11 10.81 47.52

140 Pigeon 1,125 4.65 24.92 49.94 5.24 48.61 20.00 28.70

141 Otter Cr – Plymouth 653 4.75 14.85 63.25 5.22 20.83 36.96 31.25

142 Weedens 5,128 4.51 61.84 38.59 4.98 19.87 13.79 26.94

143 Kettle Moraine 1,518 4.47 44.82 41.95 5.82 39.76 36.36 11.81

144 West Branch Milwaukee 13,871 3.99 19.19 60.92 7.63 .00 .00 .29

145 Parnell 311 4.66 50.94 39.34 4.12 57.59 58.33 27.85

146 East Branch Milwaukee 1,376 4.20 16.67 63.27 4.20 32.24 50.00 68.31

147 Crooked 2,051 2.54 6.49 100.00 4.34 84.81 27.78 12.03

148 Wallace 1,528 4.86 29.70 45.37 4.60 55.49 45.16 29.48

149 Hanneman 2,478 4.89 44.39 39.48 4.84 60.83 40.00 34.10

150 Mayfield Cr 3,377 3.51 32.27 54.73 5.46 7.65 33.33 7.65

151 Friedens 8,416 4.47 51.36 40.53 5.67 17.28 55.00 14.73
Appendixes 133

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.00 12.00 35.00 0.00 95.00 5.00 0.00 6.11 91 4

.00 11.00 25.00 .00 93.87 6.13 .00 77.02 114 4

.00 28.00 40.00 .00 70.68 26.95 .00 68.11 84 9

.00 18.00 55.00 .00 88.52 7.25 .00 35.65 84 10

.00 22.00 50.00 20.75 64.15 11.32 16.98 56.60 50 10

.00 14.00 35.00 .00 65.84 28.30 .00 56.82 74 8

.00 16.00 40.00 .00 100.00 .00 .00 .00 36 1

.00 29.00 40.00 .00 43.20 1.45 .00 18.77 206 9

.00 14.00 27.00 .00 48.15 11.11 3.70 50.00 52 6

.00 22.00 30.00 .00 25.43 3.47 .00 59.54 162 10

.00 26.00 27.00 6.96 16.16 8.08 .28 72.98 249 18

.00 26.00 25.00 .09 14.89 11.89 .00 53.30 908 13

.00 16.00 25.00 .00 36.45 36.61 .00 87.82 213 9

1.91 27.00 40.00 2.22 48.56 29.93 .22 42.35 258 22

.00 10.00 70.00 46.51 51.16 .00 48.84 2.33 30 4

8.37 16.00 45.00 .00 77.16 11.06 10.42 61.54 104 11

2.76 18.00 55.00 .00 90.47 6.86 .00 26.11 131 13

5.33 14.00 10.00 .00 73.03 20.22 .00 49.44 30 6

.00 4.00 .00 41.67 50.00 8.33 .00 50.00 12 5

11.40 37.00 37.00 .00 73.06 1.46 .00 50.36 206 8

.00 15.00 .00 .00 30.41 6.08 .00 69.59 50 6

.00 8.00 .00 .00 44.64 18.75 .00 63.39 38 5

.00 23.00 25.00 .00 96.91 3.00 .00 94.29 733 6

.38 9.00 25.00 1.92 78.85 9.62 .00 92.31 50 6

.00 16.00 25.00 .00 75.63 14.21 .00 52.28 177 8

.00 37.00 40.00 .29 51.70 5.92 3.30 22.21 711 14

.00 30.00 30.00 1.47 52.11 17.77 .00 46.42 865 11

.42 46.00 32.00 1.14 42.24 22.37 1.14 51.83 395 16

.00 29.00 35.00 1.40 20.30 14.59 .00 80.28 626 17

.00 22.00 35.00 .41 69.67 16.60 .00 83.61 271 14

3.79 17.00 17.00 .00 76.88 19.17 1.98 69.96 469 7

.00 24.00 40.00 .00 39.54 2.29 .00 36.60 222 12

.00 26.00 45.00 1.27 66.76 24.73 1.27 32.06 354 17

.00 18.00 35.00 1.67 55.00 .00 .00 45.00 43 10

.00 31.00 35.00 1.67 43.75 13.33 5.42 56.67 170 14

.00 25.00 30.00 .00 37.27 18.03 2.27 64.09 475 13

.00 9.00 35.00 .00 77.55 15.65 .00 86.39 140 9

.00 20.00 30.00 .00 42.42 13.13 .00 61.62 71 10
134 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

152 Pigeon Cr – Theinsville 800 4.53 46.71 41.10 4.23 48.78 38.46 24.39

153 Willow Cr – Germantown 1,303 4.54 17.78 58.93 5.99 6.90 11.76 6.21

154 Little Menomonee 1,305 4.62 59.87 38.14 4.49 25.81 35.71 40.65

155 Husher 912 4.15 61.37 41.22 5.79 15.38 9.52 10.77

156 North Branch Pike 3,424 3.66 59.48 45.88 6.30 .00 .00 1.19

157 Willow Cr – Waupun 550 4.39 28.13 49.36 7.01 4.71 7.69 .52

158 Flynn 221 4.61 27.84 48.01 4.16 79.20 50.00 28.76

201 Galena 12,363 3.79 63.67 44.08 4.58 83.13 33.33 11.08

202 Skinner Cr – Klondyke 23,008 4.67 83.67 35.37 5.64 70.00 43.75 52.14

203 East Branch Pecatonica 2,162 4.68 67.67 36.72 4.27 46.28 40.00 9.57

204 Little Sugar 30,670 4.51 60.33 38.77 4.75 70.06 40.91 18.64

205 West Branch Sugar – #1 4,137 4.56 52.67 39.70 4.71 84.66 60.71 23.93

206 Platte – Rockville 3,114 4.21 72.67 39.51 4.67 36.76 32.56 18.38

207 Pigeon 9,212 4.55 70.00 37.32 5.14 73.06 46.15 16.06

208 Rattlesnake 1,369 4.01 74.33 40.91 6.41 3.87 4.55 2.21

209 Blake 6,691 4.26 76.67 38.77 5.49 10.65 23.33 2.37

210 Fennimore 6,408 4.11 81.00 39.56 5.41 44.53 33.33 4.86

211 Black Earth 1 3,942 4.51 34.33 45.21 5.02 48.89 40.00 25.93

212 Kickapoo 12,823 3.63 34.00 52.73 4.67 62.58 47.22 11.04

213 Moore 4,259 3.87 54.00 44.76 4.60 36.69 37.50 44.60

214 Coon Cr 40,143 3.88 35.33 49.71 4.08 76.42 51.61 24.12

215 Little La Crosse – Sparta -- 4.40 54.00 40.55 4.32 30.14 47.37 11.42

216 Lacrosse 5,539 3.98 41.00 46.83 5.27 68.42 45.45 23.44

217 Eau Galle 2 5,996 3.86 32.33 51.27 3.71 62.79 35.71 20.93

218 Willow 2,517 4.42 24.00 52.24 -- -- -- --

219 Wood 84 2.46 18.33 52.07 -- -- -- --

220 Yellow – Barron 457 3.69 40.00 32.66 -- -- -- --

221 Hay River 903 4.15 42.00 29.30 -- -- -- --

222 North Fork Eau Claire 1,303 3.71 66.00 30.66 -- -- -- --

223 Big Eau Pleine 2,856 4.74 95.33 23.75 -- -- -- --

224 Black 722 4.16 83.33 27.10 -- -- -- --

225 Yellow – Babcock 902 4.12 55.00 28.48 5.42 29.33 20.00 2.00

226 Little Yellow 752 2.72 45.33 42.17 8.43 1.49 8.70 .00

227 South Branch Yellow 4,043 2.68 34.67 43.97 6.91 15.45 17.65 2.08

228 Ten Mile Cr 5,562 3.77 34.67 32.80 2.20 63.22 41.38 14.94

229 Little Plover 1,711 2.58 25.67 47.24 3.39 28.68 17.65 .78

230 Tomorrow 1,853 3.07 4.67 73.24 2.74 54.93 51.52 19.01

231 Pensaukee – Krakow 1,621 4.80 39.33 26.23 6.63 78.62 23.08 22.64
Appendixes 135

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.00 13.00 40.00 9.78 56.00 8.44 0.00 48.44 221 12

1.38 17.00 35.00 .76 51.52 30.30 .00 65.91 132 11

.65 14.00 37.00 .00 85.87 9.78 .00 20.65 60 7

.00 21.00 20.00 .00 65.26 27.37 .00 82.11 68 9

.00 15.00 20.00 2.66 23.32 66.62 .00 87.03 248 15

1.05 39.00 30.00 .00 49.14 23.80 .00 54.33 396 14

.00 26.00 15.00 2.36 23.62 5.51 .00 74.02 98 6

.24 24.00 25.00 11.97 41.88 43.59 24.79 46.15 15 12

.00 16.00 10.00 1.85 14.81 51.85 3.70 72.22 23 12

4.79 25.00 32.00 5.58 28.43 46.19 1.52 50.25 34 24

.00 22.00 38.00 13.87 66.47 19.65 65.90 20.23 77 4

.00 28.00 20.00 2.44 15.85 81.10 12.80 81.71 83 11

.00 43.00 47.00 1.19 68.77 7.11 6.52 7.31 89 17

.00 26.00 30.00 2.08 58.31 28.00 3.67 28.36 359 14

.00 44.00 30.00 2.11 64.43 25.51 2.81 26.13 298 15

.59 30.00 20.00 1.54 37.43 52.99 1.60 53.87 598 13

.81 36.00 20.00 .30 6.53 64.09 3.26 80.42 183 11

.00 30.00 40.00 24.20 10.50 65.30 7.31 66.21 50 8

1.23 36.00 35.00 5.22 26.10 25.70 2.81 65.06 39 24

.00 32.00 40.00 .98 33.66 21.38 2.21 62.90 174 20

.00 31.00 50.00 67.31 7.31 25.38 8.46 26.92 54 7

.46 19.00 30.00 65.04 4.88 22.76 .00 30.08 38 5

.00 33.00 52.00 14.00 56.00 6.00 30.00 6.00 9 12

.00 42.00 47.00 .00 77.78 15.07 57.21 19.47 371 13

-- -- 67.00 6.73 75.78 16.59 16.59 16.59 27 15

-- -- 50.00 5.08 83.62 7.91 11.30 11.30 45 18

-- -- 70.00 1.92 49.27 6.34 14.40 7.73 189 33

-- -- 60.00 2.27 47.73 2.27 43.18 20.45 7 14

-- -- 70.00 .67 66.64 12.16 12.99 16.19 406 23

-- -- 74.00 6.10 68.92 .32 15.02 .80 156 21

-- -- 70.00 32.94 55.29 11.76 51.76 11.76 11 11

2.00 30.00 30.00 .00 82.89 10.53 2.63 13.16 18 15

.00 23.00 20.00 5.32 54.26 39.36 5.32 53.19 35 13

9.55 51.00 45.00 1.55 95.36 1.55 1.86 10.84 100 13

.00 29.00 50.00 18.07 46.99 34.94 34.94 36.14 24 9

.00 17.00 70.00 50.42 32.77 16.81 76.47 18.49 49 5

.00 33.00 70.00 59.06 26.17 13.42 46.31 13.42 48 6

.00 13.00 40.00 .00 66.36 9.81 .00 47.20 74 14
136 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

232 Pensaukee – Pensaukee 2,768 4.12 25.37 32.41 4.44 51.01 54.84 64.93

233 Middle Branch Embarrass 1,015 4.36 11.33 40.05 3.70 39.71 41.18 .74

234 Eau Claire – Kelly 2,661 4.28 3.67 74.18 3.08 25.00 31.82 69.74

235 Eau Claire – Antigo 2,997 3.33 28.33 37.61 4.11 78.74 52.17 6.90

236 Spring Brook 2 4,389 3.55 27.33 35.93 4.00 .49 20.00 .00

237 Prairie 1,010 3.71 16.67 38.95 2.58 34.08 50.00 56.95

238 Skinner 139 2.75 44.00 41.77 4.10 42.33 28.57 .00

239 Spirit 447 4.53 9.67 41.94 4.16 84.72 51.52 4.63

240 North Fork Copper 531 4.41 8.33 45.63 3.58 59.02 31.82 23.77

241 Hunting 1,230 3.67 12.00 43.59 3.15 73.95 50.98 43.14

242 Wolf River 705 2.62 9.33 59.30 2.81 69.68 60.53 25.81

243 North Branch Pike 650 2.29 4.67 84.79 2.58 44.19 54.00 30.23

244 Popple 156 2.66 11.67 54.78 2.55 78.42 60.47 29.50

245 Woods 536 4.40 27.33 30.27 1.86 74.60 59.70 26.70

246 Pine 1,280 1.89 3.00 100.00 4.00 99.17 42.86 .00

247 Brule 627 2.40 7.00 69.50 3.62 47.10 38.00 23.87

248 Kaubashine 1,074 3.86 11.67 42.62 7.92 8.59 19.23 4.91

249 Namekagon 137 2.51 3.67 91.15 2.82 51.35 60.47 41.62

250 Totagatic 281 4.63 94.67 24.29 -- -- -- --

251 Eau Claire 982 4.18 5.00 61.71 4.05 58.05 52.27 11.49

252 Upper Ox 620 4.05 15.33 37.61 4.72 42.93 33.33 14.13

253 North Fish Cr 694 4.69 53.30 25.54 1.64 77.12 61.54 32.68

254 Bois Brule 20 3.94 23.00 34.28 2.24 78.16 62.50 14.37

255 Amnicon -- 4.72 22.00 30.31 6.44 23.45 18.42 3.54

256 Upper Tamarack 391 4.63 6.33 51.51 3.90 88.46 36.36 1.65

257 Turtle Cr 2 1,628 4.63 44.00 41.15 4.75 53.72 36.96 23.62

258 Whitewater Cr 11,991 4.01 20.67 58.83 5.88 2.58 11.76 5.73

259 Token Cr 625 4.41 30.33 47.86 6.16 7.05 10.53 1.28

260 Yahara 15,612 3.99 21.67 57.86 5.47 25.87 25.00 13.93

261 Oconomowoc 5,280 4.47 29.33 48.03 5.45 24.35 28.13 43.04

262 Milwaukee 1,936 4.82 37.33 42.06 4.76 76.63 37.93 .54

263 Cedar Cr 17,460 4.89 39.67 40.85 5.78 28.25 36.59 27.14

264 Sauk 1,873 4.90 85.00 33.90 7.04 4.07 10.00 .00

265 Stoney 2,082 4.60 34.67 44.49 3.97 58.85 52.17 66.51

266 North Branch Milwaukee 2,132 4.69 38.67 42.35 6.62 4.59 13.33 2.14

267 West Branch Rock 20,485 4.55 52.00 39.88 5.26 80.05 36.36 13.21

268 Onion 2,458 4.91 34.33 42.74 5.15 76.69 34.48 4.21

269 South Branch Sheboygan 6,796 4.61 46.67 40.58 7.40 23.02 22.22 24.40
Appendixes 137

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.00 31.00 60.00 25.30 48.19 16.87 34.94 16.87 14 14

.00 17.00 55.00 .16 62.30 16.88 1.85 30.87 179 22

.00 22.00 75.00 4.94 86.29 .90 50.79 1.80 67 22

.00 23.00 45.00 1.84 50.41 7.55 3.06 48.16 84 15

.00 5.00 100.00 73.46 25.31 .00 96.60 3.09 154 5

.00 32.00 55.00 34.60 33.68 24.64 54.91 29.10 130 19

24.72 21.00 55.00 .08 66.05 9.80 12.25 32.69 365 20

2.31 33.00 55.00 5.93 71.51 14.24 2.97 25.52 48 17

.00 44.00 40.00 9.16 46.56 27.48 15.27 52.67 55 14

.00 51.00 70.00 9.36 63.69 9.22 12.82 26.96 501 18

.00 38.00 44.00 4.92 84.43 1.64 13.93 11.48 15 13

.58 50.00 50.00 16.30 43.17 6.61 47.14 40.53 59 9

.72 43.00 40.00 .36 77.86 11.79 .36 21.43 35 15

.00 67.00 40.00 5.03 29.54 20.57 10.28 64.77 224 16

.17 7.00 57.00 14.88 82.14 .00 30.95 2.98 21 10

3.87 50.00 52.00 12.27 38.99 10.47 22.74 49.82 35 17

.61 26.00 40.00 .48 24.16 3.68 .80 71.68 287 13

.54 43.00 75.00 12.14 78.60 2.00 15.39 5.63 100 18

-- -- 62.00 5.71 59.93 23.57 20.35 29.53 164 23

.00 44.00 65.00 1.05 81.18 5.26 5.79 13.29 132 17

.54 54.00 40.00 10.26 41.03 11.54 26.50 46.58 80 11

.00 26.00 70.00 74.54 21.47 3.68 21.47 3.68 54 6

.00 40.00 70.00 66.22 19.06 4.68 13.71 14.38 39 15

21.24 38.00 30.00 2.26 65.66 26.79 1.89 59.62 105 13

2.20 22.00 57.00 7.41 74.07 3.13 5.98 23.65 70 18

.97 46.00 52.00 1.78 74.56 9.76 5.03 10.06 42 21

.00 34.00 45.00 .16 87.73 11.70 13.10 12.85 276 12

.64 38.00 20.00 6.45 58.06 35.48 54.84 38.71 15 4

.00 36.00 30.00 6.81 46.81 38.72 14.47 53.19 86 18

.43 32.00 54.00 17.36 60.88 19.32 16.63 25.92 147 21

.00 29.00 69.00 13.51 70.72 10.81 15.77 10.81 28 20

.37 41.00 47.00 13.10 75.95 10.95 12.44 25.79 173 17

3.52 40.00 .00 .00 33.33 4.17 .00 68.75 44 7

.00 23.00 57.00 .67 34.83 19.33 .45 64.94 247 19

.61 45.00 62.00 2.43 80.10 15.05 2.43 19.42 41 21

.54 22.00 .00 .00 27.66 72.34 .00 82.98 13 6

.28 29.00 52.00 7.37 68.84 23.80 7.08 23.80 65 15

1.37 36.00 22.00 1.81 30.02 30.10 .00 65.54 620 15
138 Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin

Appendix 4. Biological data for each of the 240 studied wadeable streams in Wisconsin—Continued. All data collected by the 

Wisconsin Department of Natural Resources.

[Cr, Creek; Trib, Tributary; Br, Brook; ID, identification number EPT, Ephemeroptera, Plecoptera, or Trichoptera; mg/m2, milligram per square meter; 

--, no data collected at site]

ID 

(see 

fig. 4)

Stream name

Benthic 

chlorophyll a

(mg/m2

)

Diatom 

Nutrient 

Index

Diatom 

Siltation 

Index

Diatom 

Biotic 

Index

Hilsenhoff 

Biotic 

Index 

Percent 

EPT 

number

Percent 

EPT 

taxa

Percent 

scrapers

270 Meeme 5,249 4.58 41.67 42.11 7.23 5.91 11.43 0.39

271 Silver Cr 13,180 4.72 52.00 38.80 7.70 5.15 22.22 .74

272 South Branch Manitowoc 6,716 4.77 51.33 38.64 8.40 18.64 15.63 .45

273 Manitowoc 18,736 4.76 59.33 37.35 5.06 42.78 44.74 8.33

274 East Twin 16,379 4.52 63.33 38.29 5.23 39.80 29.41 27.55

275 Neshota 2,077 4.88 15.33 61.42 4.90 25.00 9.52 8.93

276 Kewaunee 4,428 4.67 47.67 39.97 4.72 83.44 45.83 24.50

277 East 8,536 4.29 70.67 39.06 7.85 7.85 17.65 3.66

278 Duck Cr 7,653 4.74 66.67 36.51 4.89 73.04 47.83 16.67

301 Vismal Cr 4,333 2.29 6.33 74.40 -- -- -- --

302 Levis Cr 75,030 2.87 3.00 97.60 -- -- -- --

303 Ditch #6 South Branch 

Ten Mile Cr

337,121 4.56 42.67 27.03 -- -- -- --

304 South Branch Suamico 1,068,000 3.93 40.30 30.89 -- -- -- --

305 West Branch Red 239,188 2.85 12.00 51.66 -- -- -- --
Appendixes 139

Percent 

shredders

Number 

of taxa

Fish index 

of biotic 

integrity 

Percent 

carnivores

Percent 

insectivores

Percent 

omnivores

Percent 

intolerant 

species

Percent 

tolerant 

species

Number 

of fish

Number 

of fish 

species

0.00 35.00 50.00 0.67 62.97 26.01 0.47 37.43 2147 15

7.35 27.00 32.00 1.70 58.52 28.98 .00 39.77 152 11

7.05 32.00 20.00 4.55 23.94 70.91 4.85 74.24 47 22

.83 38.00 69.00 20.51 59.68 12.67 22.58 12.90 54 23

.00 34.00 77.00 7.74 81.98 7.36 11.29 14.59 171 25

.00 21.00 55.00 .61 37.40 14.42 5.53 40.30 663 19

.00 24.00 69.00 7.53 66.97 18.99 20.00 19.55 179 23

.52 34.00 .00 4.55 59.09 31.82 .00 40.91 8 10

.00 23.00 55.00 3.96 69.23 3.30 3.41 28.68 171 14

-- 33.00 -- -- -- -- -- -- -- --

-- 29.00 -- -- -- -- -- -- -- --

-- 50.00 -- -- -- -- -- -- -- --

-- 32.00 -- -- -- -- -- -- -- --

-- 36.00 -- -- -- -- -- -- -- --
Robertson, D.M., Graczyk, D.J., Garrison, P.J., Wang, L., LaLiberte, G., and Bannerman, R.

—

Nutrient Concentrations and Their Relations to the Biotic Integrity of Wadeable Streams in Wisconsin—Professional Paper 1722

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