U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2008–1015

In cooperation with the University of Wisconsin–Madison Discovery Farms program and 

the University of Wisconsin–Platteville Pioneer Farm program

Methods of Data Collection, Sample Processing, and 

Data Analysis for Edge-of-Field, Streamgaging, 

Subsurface-Tile, and Meteorological Stations at 

Discovery Farms and Pioneer Farm in Wisconsin, 2001–7

Methods of Data Collection, Sample 

Processing, and Data Analysis for 

Edge-of-Field, Streamgaging, 

Subsurface-Tile, and Meteorological 

Stations at Discovery Farms and 

Pioneer Farm in Wisconsin, 2001–7

By Todd D. Stuntebeck, Matthew J. Komiskey, David W. Owens, and 

David W. Hall

In cooperation with the University of Wisconsin–Madison Discovery Farms 

program and the University of Wisconsin–Platteville Pioneer Farm program

Open-File Report 2008–1015

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

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

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Stuntebeck, T.D., Komiskey, M.J., Owens, D.W., and Hall, D.W., 2008, Methods of data collection, sample 

processing, and data analysis for edge-of-field, streamgaging, subsurface-tile, and meteorological stations at 

Discovery Farms and Pioneer Farm in Wisconsin, 2001–7: U.S. Geological Survey Open-File Report 2008–1015, 

51 p.

Cover photos (clockwise from left): edge-of-field station, streamgaging station, meteorological station, and 

subsurface-tile station.
iii

Contents

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

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

Purpose and Scope ..................................................................................................................... 3

Project Data Objectives.............................................................................................................. 3

Water-Quantity and Water-Quality Data......................................................................... 4

Meteorological Data .......................................................................................................... 4

Data Archiving..................................................................................................................... 5

Description of Study Areas ........................................................................................................ 5

Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological 

Stations ................................................................................................................................... 10

Edge-of-Field Stations............................................................................................................... 10

Equipment........................................................................................................................... 10

Equipment Enclosures ............................................................................................ 10

Stage and Discharge Equipment........................................................................... 11

Water-Quality Sampling Equipment...................................................................... 15

Data Capture, Measurement, and Program Control ......................................... 16

Communication ........................................................................................................ 17

Power. ....................................................................................................................... 18

Miscellaneous Equipment...................................................................................... 19

Runoff-Event Monitoring and Water-Quality Sample Collection .............................. 19

Runoff-Event Monitoring ........................................................................................ 20

Sample Collection for Runoff Events .................................................................... 21

Time-Paced Compared to Volume-Paced Sampling................................. 21

Sampling Frequency....................................................................................... 21

Program Logic and Sampler Function......................................................... 22

Sample Pickup................................................................................................. 22

Sample Collection for Quality Assurance and Quality Control......................... 22

Field Blanks...................................................................................................... 23

Cross-Section Coefficient Samples............................................................. 23

Maintenance...................................................................................................................... 23

Streamgaging Stations ............................................................................................................. 25

Equipment........................................................................................................................... 25

Discovery Farms....................................................................................................... 25

Pioneer Farm ............................................................................................................ 25

Sample Collection............................................................................................................. 26

Sample Collection and Pickup for Runoff Events ............................................... 26

Sample Collection during Base Flow.................................................................... 26

Maintenance...................................................................................................................... 26
iv

Contents (cont.)

Subsurface-Tile Stations .......................................................................................................... 27

Equipment........................................................................................................................... 27

Subsurface Tiles within Fields............................................................................... 27

Subsurface Tiles at Outlets .................................................................................... 28

Sample Collection............................................................................................................. 28

Maintenance...................................................................................................................... 29

Meteorological Stations ........................................................................................................... 30

Equipment........................................................................................................................... 30

Maintenance...................................................................................................................... 30

Sample Processing for Edge-of-Field, Streamgaging, and Subsurface-Tile Stations ............ 32

Sample Processing for Samples Sent to the Water and Environmental Analysis 

Laboratory...................................................................................................................... 32

Splitting Records............................................................................................................... 32

Edge-of-Field Stations............................................................................................. 33

Streamgaging Stations ........................................................................................... 33

Subsurface-Tile Stations ........................................................................................ 34

Laboratory Procedures.................................................................................................... 35

Splitting Procedures................................................................................................ 35

Filtering...................................................................................................................... 35

Sample Processing for Samples Sent to the Wisconsin State Laboratory of Hygiene . 36

Splitting Procedures......................................................................................................... 36

Filtering............................................................................................................................... 36

Laboratory Quality Assurance and Quality Control.............................................................. 37

Data Analysis for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological 

Stations ................................................................................................................................... 37

Edge-of-Field Stations............................................................................................................... 37

Water-Quantity Data Analyses....................................................................................... 37

Water-Quality Data Analyses.......................................................................................... 39

Estimating Constituent Concentrations for Unsampled Runoff Events.................... 39

Streamgaging Stations ............................................................................................................. 40

Water-Quantity Data Analyses....................................................................................... 40

Water-Quality Data Analyses.......................................................................................... 40

Estimating Constituent Concentrations for Significant Unsampled 

Runoff Events ....................................................................................................... 41

Daily and Annual Load Computation ............................................................................. 41

Subsurface-Tile Stations .......................................................................................................... 41

Water-Quantity Data Analyses....................................................................................... 41

Water-Quality Data Analyses.......................................................................................... 42

Estimating Constituent Concentrations for Significant Unsampled 

Runoff Events ....................................................................................................... 42

Meteorological Data.................................................................................................................. 42

Summary and Conclusions................................................................................................................ 43

Acknowledgments.............................................................................................................................. 44

References........................................................................................................................................... 44

Appendixes .......................................................................................................................................... 46
v

Figures

1. Screen capture showing an example of data that can be viewed on 

NWISWeb, the U.S. Geological Survey National Water Information 

System public web interface ............................................................................................. 5

2. Map showing the locations of farms in the Discovery Farms and Pioneer 

Farm programs in Wisconsin............................................................................................. 8

3–10. Photographs showing:

 3. A typical station for the Discovery Farms and Pioneer Farm programs, 

including an aluminum, clam-style enclosure to protect weather-sensitive

instrumentation........................................................................................................... 11

 4. Staff gage, bubble tubing, sample-intake line, and heat tape of an 

H flume (2.5 feet in height) used to measure discharge ...................................... 12

 5. Plywood wingwalls used at most edge-of-field stations to provide a flumemounting surface and to direct all surface-water runoff through the flume ... 12

 6. Concrete wingwalls used at edge-of-field stations where soils were 

typically saturated most of the year........................................................................ 13

 7. Measurements of the cork line on the crest-stage gages made after a

surface-water runoff event....................................................................................... 14

 8. Ice removed from H flumes before runoff events ................................................. 15

 9. Automated, refrigerated samplers were used to collect samples of 

runoff water................................................................................................................. 15

 10. A Campbell Scientific, Inc., CR10X datalogger, an RF400 spreadspectrum radio/modem, and a battery typically used for all edge-offield, streamgaging, subsurface-tile, and meteorological stations ................... 16

11. Screen capture showing Campbell Scientific, Inc., PC208W datalogger 

communication software used to communicate with stations.................................. 17

12–13. Photographs showing:

 12. Remote-start generators used to provide AC power at some stations............. 18

 13. Streamgaging station with power provided by solar panels for sample 

refrigeration and wintertime deicing ...................................................................... 19

14. Screen capture showing Real Time Data Monitoring Software data display 

which allowed rapid assessment of many datalogger variables over time ..... 20

15–22. Photographs showing:

 15. Snow cleared downstream from the flume to prevent backwater conditions... 24

 16. Sheet piling and earthen berms used as wingwalls for the streamgaging 

stations at Discovery Farms ..................................................................................... 25

 17. U.S. Geological Survey field technician making a discharge measurement 

at a streamgaging station at Pioneer Farm............................................................ 26

 18. A 5-foot-diameter culvert installed to allow access to in-field subsurface 

tiles................................................................................................................................ 27

 19. Extra-large, 60-degree, v-throat, trapezoidal flumes installed inline with 

subsurface tiles within fields to compute discharge. .......................................... 28

 20. Extra-large, 60-degree, v-throat, trapezoidal flumes used to compute 

discharge at the outlets of subsurface tiles .......................................................... 29

 21. Meteorological station equipment typically measured precipitation, 

wind speed and direction, air and soil temperature, relative humidity, 

solar radiation, and soil moisture ............................................................................ 31

 22. Soil-temperature probes ready for installation ..................................................... 32
vi

Figures (cont.)

23. Screen capture showing an example of a splitting record summary 

showing which samples to combine and the proper aliquot sizes to create 

a discharge-weighted composite sample. .................................................................... 33

24. Graph showing an example hydrograph showing the method used for 

determining the start and end of a runoff event at a streamgaging station............ 34

25–26. Photographs showing:

 25. A set of water-quality sample bottles prior to compositing ................................ 35

 26. Churn splitters and Wisconsin State Laboratory of Hygiene sample 

bottles used for preparing samples from the Buffalo County 

Discovery Farm ........................................................................................................... 37

27–28. Graphs showing:

 27. An example of corrections made to discharge data using HYDRA during

periods that ice formed in the flume during a runoff event................................. 38

 28. An example of corrections made to discharge data due to surcharge 

conditions in a subsurface tile. ................................................................................ 42
vii

Appendixes

1. Example of a sample-retrieval sheet.............................................................................. 47

2. Example of a miscellaneous-note sheet........................................................................ 48

3. Example of a splitting record........................................................................................... 49

4. Example portion of a data-summary spreadsheet....................................................... 50

Tables

1. Data type and collection frequency for Discovery Farms and Pioneer Farm............ 3

2. Constituent and physical-property analysis list for Discovery Farms and 

Pioneer Farm ........................................................................................................................ 4

3. Edge-of-field, streamgaging, subsurface-tile, and meteorological stations 

at Discovery Farms.............................................................................................................. 6

4. Edge-of-field, streamgaging, subsurface-tile, and meteorological stations 

at Pioneer Farm.................................................................................................................... 9

5. Equipment used for collection of water-quantity, hydrologic, and waterquality data ......................................................................................................................... 10

6. Equipment used for collection of meteorological data ............................................... 30
viii

Conversion Factors and Abbreviated Units of 

Measurement

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

micrometer (μm) 0.001 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

Flow rate

liter (L) 0.2642 gallon (gal)

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

Application rate

pounds per acre per year 

[(lb/acre)/yr]

 1.121 kilograms per hectare per year

[(kg/ha)/yr]

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

follows:

°F=(1.8×°C)+32
Introduction 1

Abstract

The University of Wisconsin (UW)–Madison Discovery Farms (Discovery Farms) and UW–Platteville Pioneer 

Farm (Pioneer Farm) programs were created in 2000 to 

help Wisconsin farmers meet environmental and economic 

challenges. As a partner with each program, and in cooperation with the Wisconsin Department of Natural Resources 

and the Sand County Foundation, the U.S. Geological 

Survey (USGS) Wisconsin Water Science Center (WWSC) 

installed, maintained, and operated equipment to collect 

water-quantity and water-quality data from 25 edge-offield, 6 streamgaging, and 5 subsurface-tile stations at 7 

Discovery Farms and Pioneer Farm. The farms are located 

in the southern half of Wisconsin and represent a variety of 

landscape settings and crop- and animal-production enterprises common to Wisconsin agriculture. Meteorological 

stations were established at most farms to measure precipitation, wind speed and direction, air and soil temperature 

(in profile), relative humidity, solar radiation, and soil 

moisture (in profile). Data collection began in September 

2001 and is continuing through the present (2008).

This report describes methods used by USGS WWSC 

personnel to collect, process, and analyze water-quantity, 

water-quality, and meteorological data for edge-of-field, 

streamgaging, subsurface-tile, and meteorological stations at Discovery Farms and Pioneer Farm from September 2001 through October 2007. Information presented 

includes equipment used; event-monitoring and samplecollection procedures; station maintenance; sample handling and processing procedures; water-quantity, waterquality, and precipitation data analyses; and procedures 

for determining estimated constituent concentrations for 

unsampled runoff events.

Introduction

The Wisconsin Agricultural Stewardship Initiative 

(WASI) was introduced by then Governor Tommy Thompson in May 2000 (Wisconsin Legislative Fiscal Bureau, 

2001) to help Wisconsin farmers meet environmental 

and economic challenges. This legislation established the 

University of Wisconsin (UW)–Madison Discovery Farms 

program (Discovery Farms), the UW–Platteville Pioneer 

Farm program (Pioneer Farm), and the UW Component 

Research program. The Discovery Farms program (http://

www.uwdiscoveryfarms.org/, last accessed February 8, 

2008) was developed to conduct environmental systems 

research on privately owned farms across the state, representing a variety of farming enterprises and management 

systems, to demonstrate the adaptability and practicality 

of agricultural management practices in diverse landscape 

settings. The Pioneer Farm program (http://www.uwplatt.

edu/pioneerfarm/, last accessed February 8, 2008) was 

developed to conduct environmental systems research in 

a controlled setting on Pioneer Farm to test the adoptability and financial ramifications of a set of agricultural 

practices and technologies that may be impractical, both 

financially and environmentally, to implement on privately 

owned production farms. The UW Component Research 

program used existing UW Agricultural Research Stations 

Methods of Data Collection, Sample Processing, 

and Data Analysis for Edge-of-Field, Streamgaging, 

Subsurface-Tile, and Meteorological Stations at 

Discovery Farms and Pioneer Farm in Wisconsin, 

2001–7

By Todd D. Stuntebeck, Matthew J. Komiskey, David W. Owens, and David W. Hall
2 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

and UW System Laboratories to develop knowledge and 

test the feasibility of new agricultural practices in highly 

controlled research settings.

U.S. Geological Survey (USGS) Wisconsin Water 

Science Center (WWSC) personnel worked cooperatively 

with the Discovery Farms and Pioneer Farm programs 

and with the Wisconsin Department of Natural Resources 

and Sand County Foundation to collect water-quantity and 

water-quality data from 25 edge-of-field, 6 streamgaging, 

and 5 subsurface-tile stations at 7 Discovery Farms and 

Pioneer Farm. The farms are located in the southern half of 

Wisconsin (fig. 2) and represent a variety of landscape settings and crop- and animal-production enterprises common 

to Wisconsin agriculture. Meteorological stations were 

established at most farms to measure precipitation, wind 

speed and direction, air and soil temperature (in profile), 

relative humidity, solar radiation and soil moisture (in 

profile). Data collection began in September 2001 and is 

continuing through the present (2008). Objectives of the 

study included (1) quantifying annual and event-by-event 

runoff volumes and losses of sediment, nutrients, and other 

selected constituents; (2) collecting meteorological data to 

help establish cause-and-effect relations between agricultural practices and water quantity and quality; (3) ensuring 

that selected data were accurate and published in USGS 

annual data reports; and (4) ensuring that all data were 

archived in USGS databases.

Many historical agricultural monitoring efforts have 

primarily focused on the major crop-growing season from 

spring through fall (generally April through October in 

Wisconsin). An incomplete record of water-quantity and 

water-quality data during the winter months (November 

through March) was acceptable given the difficulties and 

costs associated with monitoring during winter. Although 

collecting data from spring through fall was important for 

the Discovery Farms and Pioneer Farm programs, it was 

critical that monitoring take place year-round so that water, 

sediment, and nutrient losses from agricultural settings 

could be fully characterized. In recent years, the number 

and severity of winter fish kills have markedly increased, 

and incidents of well contamination associated with runoff 

from the winter spreading of animal manure on frozen 

ground have underscored the importance of collecting 

accurate data during winter (http://dnr.wi.gov/org/water/

wm/watersummary/305b_2006/agriculturalrunoff.htm, last 

accessed February 8, 2008).

Wisconsin receives an average of 30–34 inches of 

precipitation annually. The average annual snowfall ranges 

from about 30 inches in southern Wisconsin to more than 

160 inches in northern Wisconsin (Moran and Hopkins, 

2002). Subfreezing and alternating freeze-thaw conditions can extend from November into early April. Snow, 

subfreezing temperatures, and repeated freeze-thaw cycles 

often cause problems with equipment used to collect 

water-quantity and water-quality data. Common problems 

include clogging of flumes with snow and ice, freezing of 

sampling equipment and sampling lines, and periods of 

runoff that vary greatly with weather conditions. These 

problems have the potential to impair equipment functionality and to overwhelm anticipated personnel commitment 

by monitoring networks, resulting in numerous periods 

with missing or incomplete records. 

In response to the need for accurate data collection 

during winter conditions in agricultural settings, equipment 

was selected and systematic procedures used or developed 

by the USGS WWSC that provided high-quality, waterquantity and water-quality data during the full range of 

annual weather conditions. Advances in wireless telecommunication, software applications, and other technologies 

enabled researchers to exert substantially more control 

over equipment function, such as real-time adjustments to 

sample-collection frequency made from remote locations, 

than previously possible. As a result of this continual evolution and refinement of techniques, some of the methods 

currently used for data collection, sample processing, and 

data analysis used by USGS WWSC personnel to monitor 

the hydrology and water quality of farmland runoff have 

not previously been documented.
Introduction 3

Purpose and Scope

This report describes methods used by USGS WWSC 

personnel to collect, process, and analyze water-quantity, 

water-quality, and meteorological data for edge-of-field, 

streamgaging, subsurface-tile, and meteorological stations 

at Discovery Farms and Pioneer Farm from September 

2001 through October 2007. Information presented in this 

report includes equipment used; event-monitoring and 

sample-collection procedures; station maintenance; sample 

handling and processing procedures; water-quantity, waterquality, and precipitation data analyses; and procedures 

for determining estimated constituent concentrations for 

unsampled runoff events.

Project Data Objectives

A principal objective of the Discovery Farms and 

Pioneer Farm programs was to develop an understanding 

of the effect of agriculture on the quantity and quality of 

runoff water from monitored farms, including edges of 

fields, streams, and subsurface tiles. To meet this principal 

program objective, objectives of this study included (1) 

quantifying annual and event-by-event runoff volumes and 

losses of sediment, nutrients, and other selected constituents; (2) collecting meteorological data to help establish 

cause-and-effect relations between agricultural practices 

and water quantity and quality; (3) ensuring that selected 

data were accurate and published in USGS annual data 

reports; and (4) ensuring that all data were archived in 

USGS databases. Data were collected at frequencies (table 

1) designed to meet project objectives.

Table 1. Data type and collection frequency for Discovery Farms and Pioneer Farm.

[--, not published; USGS, U.S. Geological Survey]

Data type Data-collection frequency Published in 

USGS annual Water-Data Report 1, 2

Water quantity Every 1 or 5 minutes during runoff events; 

every 15 or 60 minutes otherwise 

Runoff-event total, daily mean discharge, 

daily sum discharge

Water quality Variable during runoff events, monthly for base flow

(2 weeks for Pioneer Farm base flow)

Constituent concentrations

Precipitation 1 minute Daily sum

Wind speed 15 minutes --

Wind direction 15 minutes --

Solar radiation 15 minutes --

Air temperature 15 minutes --

Relative humidity 15 minutes --

Soil temperature 15 minutes --

Soil moisture 15 minutes --

1

 Through water year 2005, the USGS Wisconsin Water Science Center’s annual Water-Data Report was titled “Water Resources Data, Wisconsin–

Water Year XXXX”, where XXXX represented the water year of the data collected (for example, “Water Resources Data, Wisconsin–Water Year 2005”).

2

 Starting with water year 2006, Water-Data Reports for each state were compiled into one national Water-Data Report, “Water-Resources Data for the 

United States: Water Year XXXX”, online at http://web10capp.er.usgs.gov/adr06_lookup/search.jsp
4 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Water-Quantity and Water-Quality Data

Water-quantity and water-quality data were collected 

so that flow (discharge) data could be combined with 

water-quality data to calculate loads (methods described 

in Porterfield (1972)), yields, and trends, which could 

subsequently be related to agricultural practices. Discharge 

data were measured continuously at all edge-of-field, 

streamgaging, and subsurface-tile stations. Measurement 

of discharge followed USGS standard procedures (Garn, 

2002). Water-quality data were determined by laboratory 

analyses of water samples collected from edge-of-field, 

subsurface-tile, and streamgaging stations for the constituents and physical properties listed in table 2.

Meteorological Data

Precipitation and other meteorological data were 

collected so they could potentially be related to changes in 

water quantity, water quality, and farm-management practices. Precipitation gages were used to provide estimates of 

unfrozen precipitation at each farm. Additional meteorological measurements included wind speed, wind direction, air temperature, relative humidity, solar radiation, 

soil temperatures (at 2, 5, 10, 20, 40, and 80 centimeters 

depth), and soil moisture (30-centimeter average and/or at 

10, 20, 30, and 50 centimeters depth). 

Table 2. Constituent and physical-property analysis list for Discovery Farms and Pioneer Farm.

Constituent Discovery Farms

(Nov. 2003–Jan. 2005)

Discovery Farms

(Jan. 2005 to current)

Buffalo County

Discovery Farm 

(Sept. 2001 to current)

Pioneer Farm

(May 2003 to current)

Total solids X X X

Total suspended solids X X X

Suspended sediment X X X X

Total volatile suspended solids X X X

Chloride X X X X

Nitrate plus nitrite-N X X X X

Ammonium-N X X X X

Total Kjeldahl nitrogen (filtered) X X X

Total Kjeldahl nitrogen (unfiltered) X X X X

Dissolved reactive phosphorus X X X

Total dissolved phosphorus X X X

Total phosphorus X X X

Total dissolved solids X

pH X

Alkalinity X

Specific conductance X
Introduction 5

Data Archiving

Project data were archived according to the USGS 

WWSC policies for data archiving (U.S. Geological Survey, 2000). Water-quantity and meteorological data were 

entered into the USGS National Water Information System 

(NWIS) (Mathey, 1998) database according to USGS 

procedures (Garn, 2002). Water-quality data were entered 

into the USGS QWDATA system, the water-quality 

component of the USGS NWIS system (U.S. Geological 

Survey, 2006a). Once in the database, selected parameters 

are available for use on NWISWeb, the USGS public web 

interface (http://water.usgs.gov/nwis/) (U.S. Geological 

Survey, 2002). NWISWeb output options include graphs of 

real-time discharge, water levels, and water quality; tabular 

output in HTML and ASCII tab-delimited files; and summary lists for selected stations. An example of a graphical 

display of discharge is shown in figure 1. 

Surface-water documents and records were handled 

as specified in the WWSC Surface-Water Quality-Assurance Plan (Garn, 2002). Station visits were recorded on 

field forms and/or on sample retrieval sheets. At the time 

of establishment of a station, and whenever changes at the 

station warranted, photos were taken.

Description of Study Areas

The seven farms in the Discovery Farms program were selected to include a variety of the different 

topography, soil types, and geology found in Wisconsin 

landscapes. The farms were also selected to represent a 

major portion of the diverse crop- and animal-production 

enterprises and management styles common to Wisconsin 

agriculture. A detailed description of the landscapes, production enterprises, and management styles for each farm 

is outside the scope of this report; however, the methods 

described are applicable to a wide range of landscape settings and farm types. An informational brochure describing each of the farms can be found on the Discovery Farms 

website (http://www.uwdiscoveryfarms.org/, last accessed 

February 8, 2008). Water-quantity, water-quality, and 

meteorological data were collected at 12 edge-of-field 

stations, 4 streamgaging stations, 5 subsurface-tile stations, 

6 meteorological stations, and 2 precipitation-gage-only 

stations (fig. 2; table 3).

Water-quantity, water-quality, and meteorological 

data were collected on Pioneer Farm in southwest Wisconsin (fig. 2; table 4). Data were collected at 11 edge-of-field 

stations, 2 streamgaging stations, 1 edge-of-field station 

upstream and 1 downstream from a small grass buffer 

collecting runoff from a 0.25-acre heifer feedlot, and at 1 

meteorological station. A description of the farm can be 

found on the Pioneer Farm website (http://www.uwplatt.

edu/pioneerfarm/index.html, last accessed February 8, 

2008).

Figure 1. Example of data that can be viewed on NWISWeb, 

the U.S. Geological Survey National Water Information System 

(NWIS) public web interface (http://waterdata.usgs.gov/wi/

nwis). Data shown are for the USGS streamgaging station on 

the north tributary of Traverse Valley Creek near Independence, 

Wisconsin, for January 24 through February 24, 2006.
6 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7 Table 3. Edge-of-field, streamgaging, subsurface-tile, and meteorological stations at Discovery Farms. [USGS, U.S. Geological Survey; E, estimated; n/a, not applicable] USGS station number Station name and location Station type Latitude Longitude Contributing basin size (acres) Period of record Buffalo County 053793305 Traverse Valley Creek North Tributary near Independence, Wis. Streamgaging 44°23'55" 91°33'05" 430 Sept. 2001–Dec. 2007 a 053793306 Traverse Valley Creek South Tributary near Independence, Wis. Streamgaging 44°23'44" 91°33'13" 215 Sept. 2001–Dec. 2007 a 442405091333300 Traverse Valley Creek Rain Gage #1 near Independence, Wis. Precipitation gage 44°24'05" 91°33'33" n/a May 2002–Sept. 2007 442436091331800 Traverse Valley Creek Rain Gage #2 near Independence, Wis. Precipitation gage 44°24'36" 91°33'18" n/a May 2002–Sept. 2007 Kewaunee County 442944087354100 Discovery Farms Waterway Station No. 1 near Kewaunee, Wis. Edge-of-field 44°29'44" 87°35'41" 20.5 Nov. 2003– Dec. 2007 a 442916087362600 Discovery Farms Waterway Station No. 2 near Kewaunee, Wis. Edge-of-field 44°29'16" 87°36'26" 22.1 Nov. 2003–Oct. 2006 443012087362500 Discovery Farms Waterway Station No. 3 near Kewaunee, Wis. Edge-of-field 44°30'12" 87°36'25" 13.2 Nov. 2003–Dec. 2007 a 442945087354100 Discovery Farms Tile Station Number 1 near Kewaunee, Wis. Subsurface-tile 44°29'45" 87°35'41" 20.5 Dec. 2004–Dec. 2007 a 443014087362500 Discovery Farms Tile Station Number 2 near Kewaunee, Wis. Subsurface-tile 44°30'14" 87°36'25" 13.2 Dec. 2004–Dec. 2007 a 442954087355700 Discovery Farms Weather Station near Kewaunee, Wis. Meteorological 44°29'54" 87°35'57" n/a Nov. 2003–Dec. 2007 a Lafayette County 423912090170800 Discovery Farms Waterway Station No. 1 near Belmont, Wis. Edge-of-field 42°39'12" 90°17'08" 16.9 Dec. 2003–Dec. 2007 a 423909090172100 Discovery Farms Waterway Station No. 2 near Belmont, Wis. Edge-of-field 42°39'09" 90°17'21" 17.2 Dec. 2003–Dec. 2007 a 423846090171600 Discovery Farms Waterway Station No. 3 near Belmont, Wis. Edge-of-field 42°38'46" 90°17'16" 39.5 Dec. 2003–Dec. 2007 a 423900090172100 Discovery Farms Weather Station near Belmont, Wis. Meteorological 42°39'00" 90°17'21" n/a Nov. 2003–Dec. 2007 a Manitowoc County 0408544207 Centerville Creek Upstream Station near Cleveland, Wis. Edge-of-field 43°54'24" 87°46’ 50" 495 Oct. 2004–May 2007 0408544209 Centerville Creek Downstream Station near Cleveland, Wis. Edge-of-field 43°54'46" 87°46’ 14" 641 Oct. 2004–Nov. 2006 0408544206 Centerville Creek Tributary No. 1 near Cleveland, Wis. Edge-of-field 43°54'24" 87°46'52" 14.7 Oct. 2004–May 2007 435449087461400 Discovery Farms Tile Station No. 1 near Cleveland, Wis. Subsurface-tile 43°54'49" 87°46'14" 641 Dec. 2004–Nov. 2006 435449087463600 Discovery Farms Weather Station near Cleveland, Wis. Meteorological 43°54'49" 87°46'36" n/a Oct. 2004–Dec. 2007 a 0408543907 Point Creek Waterway Station near Newton, Wis. Edge-of-field 43°58'57" 87°47'41" 295 Oct. 2004–Oct. 2006
Introduction 

7

Table 3. Edge-of-field, streamgaging, subsurface-tile, and meteorological stations at Discovery Farms—Continued.[USGS, U.S. Geological Survey; E, estimated; n/a, not applicable]

USGS station 

number Station name and location Station type Latitude Longitude

Contributing 

basin size 

(acres)

Period of record

Iowa County

054322653 Brewery Creek Tributary Upstream Station near Mineral Point, Wis. Streamgaging 42°52'54" 90°07'51" 526 Sept. 2004–Sept. 2007054322655 Brewery Creek Tributary Downstream Station near Mineral Point, Wis. Streamgaging 42°52'25" 90°08'01" 716 Sept. 2004–Sept. 2007425318090074000 Brewery Creek Tributary No. 1 near Mineral Point, Wis. Edge-of-field 42°53'18" 90°07'40" 15.8 Jul. 2004– Sept. 2007425248090074000 Discovery Farms Weather Station near Mineral Point, Wis. Meteorological 42°52'48" 90°07'40" n/a Apr. 2004–Sept. 2007

Waukesha County

431113088281000 Discovery Farms Tile Station No. 1 near Mapleton, Wis. Subsurface-tile 43°11'13" 88°28'10" 22 (E) May 2005–Dec. 2007 a431112088281000 Discovery Farms Tile Station No. 2 near Mapleton, Wis. Subsurface-tile 43°11'12" 88°28'10" 80 (E) May 2005–Dec. 2007 a431112088281100 Discovery Farms Waterway near Mapleton, Wis. Edge-of-field 43°11'12" 88°28'11" 6.1 Jun. 2005–Dec. 2007 a431113088281100 Discovery Farms Weather Station near Mapleton, Wis. Meteorological 43°11'13" 88°28'11" n/a Jun. 2005–Dec. 2007 a

a Station was active beyond the publication date of this report. 
8 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

PRICE

CLARK

DANE

POLK

GRANT

VILAS

IRON

BAYFIELD

RUSK

SAWYER

ONEIDA

MARATHON

SAUK

FOREST

TAYLOR

DOUGLAS

IOWA

DUNN

MARINETTE

ROCK

WOOD

DODGE

BARRON

LINCOLN

BURNETT

JACKSON

ASHLAND

MONROE

VERNON

JUNEAU

PORTAGE

CHIPPEWA

BUFFALO

SHAWANO

LANGLADE

GREEN

PIERCE

ST. CROIX

BROWN

COLUMBIA

LAFAYETTE

WAUSHARA

EAU CLAIRE

FOND DU LAC

FLORENCE

RACINE

OCONTO

ADAMS

DOOR

WASHBURN

WAUPACA

RICHLAND

CRAWFORD

JEFFERSON

WALWORTH

OUTAGAMIE

TREMPEALEAU MANITOWOC

WAUKESHA

WINNEBAGO

CALUMET

LA CROSSE MARQUETTE SHEBOYGAN

PEPIN

WASHINGTON

KEWAUNEE

GREEN

LAKE

KENOSHA

MENOMINEE

OZAUKEE

MILWAUKEE

88°30

90°

91°30'

46°30'

45°

43°30'

EXPLANATION

WISCONSIN

Pioneer Farm

Discovery Farms

Base from U.S Geological Survey 1:24,000 digital data

0 20 40 60 MILES

0 20 40 60 KILOMETERS

Figure 2. Locations of farms in the Discovery Farms and Pioneer Farm programs in Wisconsin.
Introduction 

9

Table 4. Edge-of-field, streamgaging, subsurface-tile, and meteorological stations at Pioneer Farm.[USGS, U.S. Geological Survey; UW, University of Wisconsin; n/a, not applicable]

USGS station 

number Station name and location Station type Latitude Longitude

Contributing 

basin size 

(acres)

Period of record

424245090235501 UW Platteville Farms Site No. 1 near Platteville, Wis. Edge-of-field 42°42'45" 90°23'55" 33.4 Mar. 2002–Sept. 2003424314090240601 UW Platteville Farms Site No. 2 near Platteville, Wis. Edge-of-field 42°43'14" 90°24'06" 18.2 Mar. 2002– Dec. 2007 a424302090225601 UW Platteville Farms Site No. 3 near Platteville, Wis. Edge-of-field 42°43'02" 90°22'56" 13.6 Mar. 2002–Dec. 2007 a

424256090234001 UW Platteville Farms Site No. 4 near Platteville, Wis. Edge-of-field 42°42'56" 90°23'40" 73.8 Mar. 2002–Sept. 2007424259090231301 UW Platteville Farms Site No. 5 near Platteville, Wis. Edge-of-field 42°42'59" 90°23'13" 14.2 Mar. 2003–Dec. 2007 a424302090230301 UW Platteville Farms Site No. 6 near Platteville, Wis. Edge-of-field 42°43'02" 90°23'03" 2.61 Mar. 2003–Sept. 2006424242090230701 UW Platteville Farms Site No. 7 near Platteville, Wis. Edge-of-field 42°42'42" 90°23'07" 43.0 Mar. 2003–Dec. 2007 a424245090231000 UW Platteville Farms Site No. 8 near Platteville, Wis. Edge-of-field 42°42'45" 90°23'10" 29.8 Nov. 2003–Dec. 2007 a424247090234500 UW Platteville Farms Site No. 9 near Platteville, Wis. Edge-of-field 42°42'47" 90°23'45" 20.4 May 2003–Sept. 2007424302090231900 UW Platteville Farms Site No. 10 near Platteville, Wis. Edge-of-field 42°43'02" 90°23'19" 10.1 Sept. 2005–Dec. 2007 a424253090232100 UW Platteville Farms Site No. 11 near Platteville, Wis. Edge-of-field 42°42'53" 90°23'21" 3.50 Sept. 2005–Dec. 2007 a424246090231700 UW Platteville Farms Site No. 12a near Platteville, Wis. Edge-of-field 42°42'46" 90°23'17" 0.25 Sept. 2005–Dec. 2007 a424245090231600 UW Platteville Farms Site No. 12b near Platteville, Wis. Edge-of-field 42°42'45" 90°23'16" 0.26 Sept. 2005–Dec. 2007 a424231090231900 UW Platteville Farms Weather Station near Platteville, Wis. Meteorological 42°42'31" 90°23'19" n/a Apr. 2003–Dec. 2007 a05414849 Galena River–UW Platteville Farms upstream site near Platteville, Wis. Streamgaging 42°43'07" 90°23'41" 1,523 Oct. 2005–Sept. 200705414850 Galena River–UW Platteville Farms downstream site near Platteville, 

Wis.

Streamgaging 42°42'39" 90° 23'58" 1,882 Jul. 2002–Dec. 2007 a

a Station was active beyond the publication date of this report. 
10 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Data Collection for Edge-of-Field, 

Streamgaging, Subsurface-Tile, and 

Meteorological Stations

Edge-of-field stations were located in waterways or 

points of concentrated flow at the edges of agricultural 

fields or in intermittent streams in any location associated 

with field drainage. Streamgaging stations were generally 

located in small, headwater streams within a primarily 

agricultural setting. Subsurface-tile stations were located 

either in fields or at tile outlets, depending on topography. 

Each of these locations may not have been at or near a 

point of easy access and therefore could be difficult to 

service during wet or winter conditions. The collection of 

water-quality samples and data generally followed USGS 

WWSC procedures (Richards and others, 2006), except as 

otherwise described in this report.

Edge-of-Field Stations

Equipment

Equipment Enclosures

Similar equipment was used for edge-of-field stations at the Discovery Farms and Pioneer Farm. In most 

instances, a custom-made, aluminum, clam-style enclosure 

was used at each station to house equipment designed to 

measure stage (water level, used to compute discharge), 

collect water samples, and provide two-way telecommunication that enabled data acquisition and real-time programming (fig. 3, table 5). The aluminum enclosures were 4 

feet wide by 2.5 feet deep by 5 feet tall when closed, and 

approximately 7 feet high when open. Hydraulic cylinders 

allowed the lid of the enclosure to easily open to allow 

equipment access but also to shelter the equipment from 

the elements during station visits. The enclosure design 

allowed it to be hand placed on four treated-wood posts or 

on wooden skids to keep it off the ground.

Table 5. Equipment used for collection of water-quantity, hydrologic, and water-quality data.

[Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.]

Equipment type Manufacturer Equipment name

Stage, discharge, and water-quality sampling

Flume Tracom, Inc. H and Trapezoidal

Datalogger Campbell Scientific, Inc. CR10 and CR10X

Pressure transducer Sutron Corporation Sutron Accubar Model 5600-0125

Gas bubbler system Rickly Hydrological Company USGS Conoflow Sight Feed Assembly

Automatic sampler Teledyne ISCO, Inc. ISCO Refrigerated R3700 with 24 polyethylene bottles

Communication

Cellular modem AirLink Communications, Inc. Raven CDMA Model C3211

Spread-spectrum radio Campbell Scientific, Inc. RF400 900 MHz

Telephone modem Campbell Scientific, Inc. COM 210

Power

Solar power inverter Exceltech, Inc. XP1100, 1100 Watt True Sine Wave

Solar power charge controller Morningstar Corporation SunGuard SG-4 and TS-45 TriStar 45

Generator Onan and Generac Onan® Microlote 2800 and Generac Quietpact 40G
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 11

Stage and Discharge Equipment

Contributing basin sizes at edge-of-field stations 

were between 0.25 and 641 acres. For these edge-of-field 

stations, standard, prerated, fiberglass H flumes of various sizes were used (fig. 4) to measure stage over time, 

which was then used to compute a continuous record of 

discharge.

A maximum anticipated discharge was estimated 

for each edge-of-field station on the basis of basin area, 

topography, and soil characteristics. Using this discharge, 

an appropriately sized H flume was selected. Discovery 

Farms and Pioneer Farm edge-of-field stations used H 

flumes between 1.5 feet and 3.0 feet in height, with maximum discharge capacities between 5.4 and 30.7 cubic feet 

per second.

An H flume was attached to a wingwall installed 

perpendicular to the direction of surface-water runoff. The 

wingwall provided a rigid location to mount the flume, and 

acted as a funnel to direct all surface-water runoff through 

the flume. The wingwall was made of either treated plywood or concrete, depending on the average soil moisture.

In locations with generally dry soils for a majority of 

the year, wooden wingwalls were constructed using 3 to 

5 sheets of 3⁄4-inch-thick, treated plywood secured to each 

other with construction adhesive and screws. A 9-inch 

overlap was used to ensure a secure, watertight connection 

between the plywood sheets. A 4- to 6-inch-wide, 2-footdeep trench was excavated perpendicular to the flow path. 

The bottom of the plywood wingwall was cut so that, when 

placed in the trench, the top of the wingwall extended 

above the ground surface to the same height as the H 

flume (fig. 5). The excavated soil was placed back into the 

trench, carefully backfilled, and firmly tamped to prevent 

water from undercutting the wingwall. Earthen berms were 

created to secure the outside edges of the wingwall and to 

ensure that all discharge passed toward the H flume.

In locations where soils were saturated for most of 

the year (runoff was more prolonged), a concrete wingwall was used to prevent undercutting that could occur if 

plywood wingwalls were used. A trench was excavated 

and a concrete wall was poured on a concrete footer. The 

concrete wingwall was built to extend above the ground 

surface to the same height as the H flume (fig. 6).

The H flumes were leveled from side to side and from 

front to back before being secured to the downstream side 

of the wingwall. Support bracing was placed at the flume 

exit to minimize flume movement. Soil erosion at the exit 

of the H flume was prevented by placing rock riprap or 

treated wood on heavy-duty landscaping fabric.

H flumes are not accurate for measuring discharge 

under certain backwater conditions. Backwater occurs 

when the flow of water downstream from the flume 

becomes partially blocked or retarded, resulting in ponding 

and subsequent water backup such that an artificially high 

stage occurs in the flume relative to the volume of water 

discharged. Occasionally, downstream grades needed to 

be modified to ensure proper measurement conditions. H 

flumes have a prerated stage to discharge relation; that is, 

if the stage in the flume is measured, the discharge can be 

determined. 

To accurately determine the discharge passing 

through an H flume, accurate stage readings are required. 

Accuracy requirements for stage measurements can be 

found in Garn (2002). Stages in the H flumes at Pioneer 

Farm were initially monitored by use of a shaft encoder 

Aluminum

enclosure

Datalogger

and electronics

Nitrogen

tank

Stage-measurement

equipment

Water-quality

H flume sampler

Figure 3. A typical station for the Discovery Farms and 

Pioneer Farm programs, including an aluminum, clam-style 

enclosure to protect weather-sensitive instrumentation.
12 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Staff

gage

Bubble

tubing

Heat

tape

Direction

of flow

Sampleintake line

Figure 4. The staff gage, bubble tubing, sample-intake line, and heat tape are shown in this photograph of an H flume (2.5 feet in 

height) used to measure discharge.

Figure 5. Plywood wingwalls were used at most edge-of-field stations to provide a flume-mounting surface and to direct all 

surface-water runoff through the flume.
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 13

and float system with a 6-inch stilling well. This method 

for monitoring stage was unsatisfactory during snowmelt 

events when nighttime temperatures fell below freezing 

because the float used for the shaft encoder became frozen 

within the stilling well and could not respond during runoff 

until it was thawed. The ice in the stilling well was difficult and time-consuming to thaw before the next precipitation or snowmelt event. Also, the float occasionally stuck 

or “hung” on the sides of the well during periods of rapid 

changes in stage during runoff events. For these reasons, 

use of the shaft encoder and float system was discontinued.

All Discovery Farms and Pioneer Farm stations eventually used nonsubmersible pressure transducers, coupled 

with nitrogen bubbler systems (Groetsch and Coleman, 

2001), to monitor stage in the H flumes. These systems 

transmitted nitrogen gas at a known rate and pressure 

through 3/8-inch black polyethylene tubing (bubble tubing). The end of the bubble tubing, or orifice, was attached 

to the floor of each flume using plastic clips (fig. 4). Stages 

measured by the system were then recorded by a datalogger. Although water occasionally froze around the bubble 

tubing during wintertime runoff events (causing higher, 

incorrect stages), the nonsubmersible pressure transducer 

and nitrogen bubbler system was easier to maintain and 

provided more accurate and reliable data than the shaft 

encoder and float system. In addition, numerous comparisons of staff-gage (fig. 4) measurements to those recorded 

by the dataloggers showed that drawdown—a phenomenon where water velocities can cause stage-measurement 

devices to read lower than the actual stage—was insignificant in H flumes where the bubble tubing was attached to 

the flume floor, even for high discharges.

A crest-stage gage (CSG) was mounted to the 

upstream side of the wingwall at most edge-of-field stations to confirm that the event-maximum stage measured 

by the pressure transducer was accurate (Garn, 2002, figs. 

8 and 15). The CSG was a 3-foot-long piece of wood with 

a small sheet metal cup at the bottom to hold shredded 

cork. The wood was placed in a 2-inch-diameter pipe that 

was capped on both ends. The bottom cap of the pipe was 

fixed and had holes to allow water to move in and out of 

the pipe. The top cap was removable and had a hole in the 

side to prevent pressure from limiting water movement. 

After a runoff event, the maximum stage was determined 

Aluminum

enclosure

Antenna

Generator

enclosure

Concrete

wingwall

Propane

tank

H flume with plywood enclosure

for wintertime monitoring

Figure 6. Concrete wingwalls were used at edge-of-field stations where soils were typically saturated most of the year.
14 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

by measuring the distance from the bottom of the piece of 

wood to the cork that remained stuck to the piece of wood 

(fig. 7). Peaks determined by the CSG were then compared 

to the peaks recorded by the datalogger. 

Staff gages also were installed to the inside of the H 

flumes, near the location where stage was measured by 

the pressure transducer (figs. 4 and 8). Each time a station 

visit was made during a time of runoff, the staff-gage 

reading was recorded to the nearest thousandth of a foot. 

The simultaneous stage reading from the datalogger also 

was recorded. Stages from the staff gage and the datalogger were compared for every station visit, and adjustments 

were made to the data during analysis.

Heat tape (similar to that used to prevent pipes from 

freezing) was attached to the bottom of the H flumes by 

making a single pass near the sample-intake line and bubble tubing and out the flume exit (figs. 4 and 8). The heat 

tape was installed to reduce or prevent ice that formed near 

the bubble tubing, sample-intake line tip, and flume exit. 

Although the heat tape did not totally prevent ice buildup 

in the flumes, it was effective at reducing water freezing at 

the tips of the sample-intake line and bubble tubing; it also 

reduced water freezing in the flume exit. Generally, the 

flume exit was the first to freeze when ice formed; it would 

cause water to back up into the flume, causing more ice 

problems when the backed-up water eventually froze. The 

heat tape helped to keep the water at the flume exit from 

freezing and thus helped to prevent further ice problems 

from developing. 

Determining the levelness of the floor of the H 

flumes was critical to obtain accurate records of discharge. 

During field testing, it was determined that, when the H 

flumes were level, measured discharge matched the rated 

discharge very closely. However, it was determined that 

a flume floor tilt from entrance to exit of just 0.02 foot in 

a 2.5-foot H flume would cause the stage to be underestimated by that same 0.02 foot. With this 0.02-foot floor tilt 

and a measured stage of 0.3 feet, the resultant discharge 

would be underestimated by more than 10 percent compared to a level flume. Therefore, although the stagedischarge relation for an H flume was stable, accuracy 

was highly dependent on the flumes being level from front 

to back and from side to side. In 2006, small levels were 

attached to the H flumes as a check of levelness. Each time 

a station visit was made, a note was made on the sample 

retrieval sheet to indicate the position of the level bubble. 

Changes to the level readings indicated that the flume 

should be resurveyed and appropriate corrections applied. 

Using survey data, corrections were made to the data to 

adjust for flume tilt.

Figure 7. Measurements of the cork line on the crest-stage gages were made after a surface-water runoff event
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 15

Water-Quality Sampling Equipment

An automated, refrigerated, 24-bottle ISCO 3700R 

sampler (fig. 9) was used to collect samples of surfacewater runoff. Samples were pumped from the H flumes 

using 3/8-inch inside by 1/2-inch outside diameter 

Teflon-lined sample tubing (sample-intake line) into 1-liter 

polypropylene bottles housed in a refrigerator. Although 

not necessary considering the constituent list, Teflon-lined 

sample tubing was used to help minimize cross-contamination between samples and to provide extra strength. The 

sample-intake line was attached within the throat of the 

flume, where the runoff-water column was presumed to 

be mixed the best, and was connected to the flume floor to 

allow samples to be collected at low runoff depths (figs. 4 

and 8).

Crest-stage

gage

Heat tape

Staff

gage

Bubble

tubing

Sampleintake line

Sampler head

Sampler pump

Sample-intake

line

1-liter 

sample bottles

Figure 8. Ice was removed from H flumes before runoff events. Here, icemelt near the bubble line and sample-intake line due to 

the heat tape can be seen.

Figure 9. Automated, refrigerated samplers were used to 

collect samples of runoff water.
16 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Protecting the sample-intake line from freezing and 

damage was an important consideration. Care was taken 

to ensure that the sample-intake line sloped downgradient 

into the flume so that water did not collect in the line and 

freeze. Heat tape and foam pipe insulation were attached 

over the length of the sample-intake line as a further precaution to prevent freezing. Thermocouple wire was also 

attached beside the sample-intake line so that temperatures 

could be monitored. The sample-intake line, heat tape, 

insulation, and thermocouple wires were protected within 

2-inch, flexible electrical conduit. Equipment enclosures 

were placed close to the point of sampling to minimize 

sample-intake line length. Average sample-intake line 

lengths for edge-of-field stations were approximately 15 

feet; head heights (vertical distance between the tip of the 

sample-intake line on the floor of the flume and the automatic sampler head) were approximately 6 feet. 

Data Capture, Measurement, and Program Control 

A critical station function was to collect and store 

data produced by the station sensors and devices and to 

control when certain functions were performed (such as 

when data were to be stored or samples collected, or when 

AC power should be activated for sample refrigeration). 

A specialized, in-house datalogger program executed by a 

Campbell Scientific, Inc., CR10 or CR10X datalogger (fig. 

10) was used to read, store, and control station sensors and 

devices. The datalogger program could easily be modified 

either at the station or remotely.

Radio/modem

Datalogger

Figure 10. A Campbell Scientific, Inc., CR10X datalogger, an RF400 spread-spectrum radio/modem, and a battery were typically 

used for all edge-of-field, streamgaging, subsurface-tile, and meteorological stations.
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 17

Communication

Two-way, real-time communication with stations 

was crucial to ensure proper equipment function, adjust 

sample frequency to maintain adequate sample coverage 

during runoff events, and allow other program changes to 

be made. This functionality also helped to minimize field 

visits and reduce the amount of lost data and unsampled 

runoff events.

Most of the Discovery Farms and Pioneer Farm edgeof-field stations were located where telephone lines were 

not available or installation was cost-prohibitive or not 

feasible; however, a telephone line was usually available 

at a central, conveniently accessible, and relatively high 

elevation location compared to the other stations. Where 

possible, a “radio base station” tower was set up at this 

location with a Campbell Scientific, Inc.COM 210 telephone modem, a Campbell Scientific, Inc.RF400 spreadspectrum radio/modem, and an omnidirectional antenna. 

Dataloggers at the edge-of-field stations were connected to 

RF400 radio/modems that had directional antennas aligned 

to target the base-station antenna. This equipment configuration allowed real-time, two-way telemetry to each datalogger from any computer with a modem and the required 

software. A Campbell Scientific, Inc.software program 

called PC208W (fig. 11) was used to dial the base-station 

phone number, connect with the modem, and then communicate with the remote field stations by tuning into one 

station after another using different RF400 radio addresses. 

Communication could be established and data retrieved 

from multiple stations with a single telephone call. 

At locations where telephone lines were not available 

or were cost-prohibitive, AirLink Communications, Inc. 

Raven cellular modems were used for communication. 

These cellular modems allowed two-way communication to the dataloggers in the same manner in which the 

telephone modems operated, but data were transmitted via 

a wireless cellular network. Rather than using a modem to 

call a station, PC208W used a broadband internet connection to establish communication with the modems by way 

of a static Internet Protocol (IP) address.

Figure 11. Campbell Scientific, Inc., PC208W datalogger communication software (sample image used with permission from 

Campbell Scientific, Inc.) used to communicate with stations.
18 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Power

Direct current (DC) and alternating current (AC) 

power were both required to operate equipment at the 

stations. The electronic equipment (including the sampler 

pump head) required DC power, whereas AC power was 

necessary for sample refrigeration and wintertime heat 

tapes. DC power was provided by 12-volt batteries of 

various sizes (usually 8- or 26-ampere-hours) that were 

charged by either AC or solar power. Most Discovery 

Farms and Pioneer Farm stations were located where it 

was neither economically feasible nor practical to obtain 

electrical service from a power company. In these cases, 

recreation-vehicle (RV) remote-start generators or solarpower panels were used to provide AC power. 

RV generators were located outside the equipment 

enclosure in a separate aluminum box (fig. 12) that was 

modified to allow air flow for both intake and exhaust. 

Landscape fabric was placed on the ground under the 

generator and equipment enclosure to prevent vegetative 

growth to reduce the potential for fires to be caused by 

heated generator exhaust. Five- to 25-gallon tanks were 

used to supply unleaded fuel to the generators. At some 

stations, sensors were installed within the tanks to monitor fuel levels. The generators were started and stopped by 

means of solid-state relays connected to the datalogger. 

Datalogger program logic determined when to start and 

stop the generators based on criteria including refrigerator 

temperature thresholds and wintertime deicing requirements. When operating correctly, the generators provided 

a steady source of power that could operate in all weather 

conditions; however, starting the generators remotely was 

sometimes difficult because of cold weather or mechanical issues. In addition, trips to the stations were sometimes 

necessary to maintain fuel levels to ensure proper sample 

refrigeration during extended periods (several days or 

more) of surface-water runoff.

Solar power was also used to provide AC power for 

sample refrigeration and to operate wintertime heat tapes 

for deicing at a number of Discovery Farms stations (fig. 

13). Equipment generally consisted of three, 80-watt solar 

panels with a Morningstar Corporation Tri-Star 45-ampere 

charge controller that charged two 12-volt, 260-amphour batteries connected in parallel. An Exceltech, Inc. 

1100-watt pure sine-wave inverter was used to convert the 

DC battery power to 120 volts AC power. The inverter was 

Generator enclosure

Generator

Fuel tank

Plywood wingwall

Figure 12. Remote-start generators were used to provide AC power at some stations.
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 19

powered on and off using a solid-state relay connected to 

the datalogger. Datalogger program logic determined when 

to start and stop the generators based on criteria including 

refrigerator temperature thresholds and wintertime deicing 

requirements.

In general, the solar-powered system was able to meet 

the power demands of the refrigerators and heat tapes. 

Extended periods of surface-water runoff (several days 

or more) necessitating sample refrigeration or periods 

in which deicing was necessary for more than a day did 

deplete the battery reserves, especially when skies were 

cloudy and/or temperatures cold. Because there were no 

moving parts in the solar power system and no fuel tanks 

to keep filled, there were fewer maintenance issues with 

the solar power compared to generator power.

Miscellaneous Equipment

Most edge-of-field stations had time-lapse cameras 

installed to take a single digital photograph every day to 

document the field-management activities and field conditions in the monitored watersheds (fig. 13). The cameras 

were mounted in a fiberglass electrical enclosure with a 

4-inch hole covered with a clear acrylic panel. Small DC 

power inverters were used to reduce the voltage to that 

required by the cameras. Images from the cameras were 

stored on flash cards, then downloaded to a laptop computer by project personnel during station visits.

Runoff-Event Monitoring and Water-Quality 

Sample Collection

Runoff at edge-of-field stations was dependent on 

many factors including type and intensity of precipitation, 

antecedent soil-moisture conditions, season, local terrain, 

soil type, crop type, and producer land-management styles. 

When runoff did occur, it was vital that equipment was 

working properly and that flexibility was programmed 

within the sampling scheme to handle the wide variety of 

runoff events that occurred. Many of the same techniques 

and procedures for runoff-event monitoring and sample 

collection were used by the Discovery Farms and Pioneer Farm programs for edge-of-field, streamgaging, and 

subsurface-tile stations.

Solar

panels

Antenna

Time-lapse

camera and enclosure

Sheet-piling

wingwall

H flume in stream

Figure 13. Streamgaging station with power provided by solar panels for sample refrigeration and wintertime deicing.
20 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Runoff-Event Monitoring

Precipitation, runoff, and equipment conditions were 

closely monitored. Sample frequency was often adjusted 

during runoff events to maintain adequate sample coverage without exceeding sampler capacity. Knowledge of 

field conditions and weather was necessary to anticipate 

when runoff might occur. If fields were snow covered 

and air temperatures were predicted to rise significantly 

above freezing, runoff was likely. Runoff was also likely 

if significant or high-intensity rainfall was predicted when 

soil moisture was high and vegetative growth was low. 

Knowledge of the typical runoff characteristics of each station was also important because it helped guide decisions 

regarding the appropriate sample frequency needed for 

adequately sampling runoff.

Data from many web-based weather stations were 

available online (www.weather.gov, www.my-cast.com, 

www.intellicast.com, among others.). Each web site offered 

different features such as long-term forecasts, expected 

precipitation amounts, and severe weather alerts. Webbased Doppler radar stations with the ability to show storm 

motion (looping) was an invaluable tool for monitoring 

runoff events, because they helped determine the likelihood, timing, intensity, and expected duration of precipitation events. Radar web sites that also allowed the user 

to display station coordinates were particularly useful, 

because the exact location of the watershed was shown in 

relation to approaching precipitation. 

When runoff was expected, the data-retrieval interval 

(set in PC208W) was reduced so that data were collected 

more frequently. Data were then automatically updated 

into Campbell Scientific, Inc., Real Time Data Monitoring 

Software (RTDM) that provided a custom-designed graphical representation of the values recorded by the datalogger 

(fig. 14). This allowed quick assessment of the data, such 

as the number of samples collected, sample frequency, rate 

of change of the hydrograph, and equipment functionality 

that would not be possible simply by calling the station 

and observing instantaneous conditions. This assessment 

also allowed rapid and accurate decisions to change the 

sampling frequency during runoff and evaluate equipment 

performance. If significant problems were found, such 

as the sampler not functioning properly or unusual stage 

values, personnel were immediately sent to the station to 

fix the problem.

Figure 14. Real Time Data Monitoring Software (RTDM) data display allowed rapid assessment of many datalogger variables 

over time (sample image used with permission from Campbell Scientific, Inc.).
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 21

Many runoff events occurred outside traditional office 

hours. At such times, USGS WWSC personnel used several tools to aid them in data and sample collection associated with the monitoring of runoff events. For example, 

Virtual Private Network (VPN) software was used to gain 

authenticated and secure access to office computers from 

any properly configured computer. Then, using Remote 

Desktop Connection (RDC), a software program from 

Microsoft Corporation, desktop computer resources—

files, preferences, and applications such as PC208W and 

RTDM—were available. Using VPN and RDC, anything 

that could be done from the WWSC office could also be 

done from offsite locations with Internet access. 

Sample Collection for Runoff Events

One of the data-collection goals of the Discovery 

Farms and Pioneer Farm programs was to collect water 

samples that adequately represented the variability in 

constituent concentrations during periods of runoff so that 

accurate constituent loads and yields could be computed. 

Collecting samples to compute loads and yields was challenging because the duration and intensity of runoff events 

at edge-of-field stations were difficult to predict and varied 

considerably from season to season, event to event, and 

within events.

An edge-of-field runoff event was defined as the time 

from the onset of rainfall- or snowmelt-induced surfacewater runoff to the time when runoff ceased. Rainfall-runoff events at edge-of-field stations that occurred during late 

spring through fall were generally short in duration (minutes to hours) but high in intensity (high rate of change 

in discharge). Rainfall- or snowmelt-runoff events that 

occurred during winter and early spring were generally 

longer in duration (hours to days) and of lower intensity. A 

single runoff event could include multiple peak discharges 

in response to changes in the intensity of rainfall or rate of 

snowmelt. In winter and early spring, above-freezing temperatures during daytime sometimes caused snowmelt-runoff events wherein runoff volume subsequently decreased 

as temperatures dropped below freezing during the night.

Time-Paced Compared to Volume-Paced Sampling

Two basic ways that samples can be collected to 

characterize a runoff event using an automated sampler 

are time paced or volume paced. Time-paced samples are 

collected at predetermined time intervals during a runoff 

event, and volume-paced samples are collected when a 

predetermined volume of water passes by the station.

When sample collection is based on volume, it is 

necessary to roughly predict both the maximum discharge 

and the volume of a runoff event in order to collect the 

appropriate number of samples to adequately characterize 

the event. If the volume between samples is set too low, the 

sampler capacity can be exceeded before the event ends or 

samples can be missed because new samples can be triggered before the previous sample is pumped. Conversely, 

it is possible to set the volume between samples too high, 

resulting in too few samples to adequately represent the 

runoff event. Although the predetermined volume can be 

modified during an event to prevent these situations, these 

modifications complicate the sample-splitting process.

Problems with volume-paced sampling can also arise 

when backwater or icing conditions exist. In either case, 

the volume between samples is computed incorrectly in 

the datalogger program, resulting in samples that are not 

representative of the true volume of water passing by the 

station. 

Because of the difficulty in predicting the maximum 

discharge and the volume of a runoff event and the issues 

that arise with backwater or icing conditions for volumepaced samples, time-paced samples were collected for 

edge-of-field stations for the Discovery Farms and Pioneer 

Farm programs. Proper use of this method resulted in the 

most reliable and most comprehensive sample coverage, 

ranging from small, short-duration runoff events to large, 

long-duration runoff events.

Sampling Frequency

Sampling frequency during a runoff event was controlled and adjusted by use of the datalogger. With remote 

communication, the datalogger program was modified 

to adjust for changing weather and runoff. The ability to 

adjust sampling frequency remotely was perhaps the most 

important technological aspect of the sampling process 

because it enabled adequate coverage of the wide range 

of discharge volumes and length of runoff events that 

occurred.

The need to adjust sampling frequency is illustrated 

in figure 14. Samples for this runoff event were initially 

collected at 35-minute intervals. Had that frequency been 

maintained for the entire runoff period, the sampler would 

have reached capacity before the end of the runoff event, 

and samples would not have been collected to represent the 

recession limb of the hydrograph. In this case, however, 

the sampling frequency was reduced to 1 hour after the 

peak, and then eventually to 3-hour intervals so that the 

sampler capacity would not be exceeded before the end 

of the runoff event. In addition, because only 17 samples 
22 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

were collected, there were still 7 samples in reserve in case 

another runoff event occurred before samples could be 

retrieved and the sampler reset. 

Program Logic and Sampler Function

The datalogger recorded stage data at 15- or 60-

minute intervals when surface-water runoff was not occurring. During runoff events, the data-recording frequency 

increased to 1 minute or 5 minutes when the stages in the 

H flume exceeded a threshold of 0.04 foot, which was just 

enough to completely submerge the bubble tubing. At this 

stage, known as the data threshold, a surface-water runoff 

event was likely occurring. Stages below this could have 

been anomalous spikes caused by direct precipitation into 

the H flume or by wind. The datalogger program entered 

sampling mode at approximately 0.08 foot—when the 

depth of water in the flume completely submerged the 

sample-intake line. Samples collected below this stage 

were likely to entrain air, resulting in improperly filled 

bottles. Once in sampling mode, the datalogger triggered 

samples based on a preset time until the stage fell below 

the sampling threshold. All thresholds were adjustable 

within the datalogger program through on-station or 

remote communication.

When a sample was triggered by the datalogger, the 

ISCO sampler responded by completing a rinse cycle to 

reduce cross contamination between samples. First, any 

residual water in the sample-intake line was purged. Runoff water was then pumped from flow in the flume through 

the sample-line tubing to the pump-head tubing and then 

purged back to the flume to complete one rinse cycle. The 

sampler then pumped the runoff water up the sample-line 

and pump-head tubing into the sample bottle. Finally, the 

sample-line tubing was purged again. No further cleaning of the sample line was done. The ISCO sampler was 

calibrated to deliver approximately 950 milliliters for each 

sample. If a sample was successfully collected, the ISCO 

sampler sent a high-frequency pulse back to the datalogger. The number of pulses sent was equivalent to the current bottle number. Use of these data from the sampler and 

datalogger was helpful to ensure proper sampler function. 

Sample Pickup

Runoff samples collected by the ISCO samplers were 

generally retrieved within 24 hours of the end of a runoff 

event. At that time, sample-retrieval sheets and/or miscellaneous-note sheets were filled out (Appendixes 1 and 2), 

and staff-gage readings in the H flumes and the corresponding stages recorded by the datalogger were noted. Samples 

were removed from the ISCO samplers, labeled, placed 

in coolers with ice, and then transported to the University 

of Wisconsin–Stevens Point Water and Environmental 

Analysis Laboratory (WEAL) in Stevens Point, Wis., for 

analysis. Samples for edge-of-field stations were typically 

received by the laboratory within 3 days of a runoff event. 

Several trips to pick up and deliver samples were typically 

made for runoff periods that lasted for more than 2 days. 

Occasionally, some samples were not received by the laboratory for 4 days or more from the time the first sample was 

collected. Effects of exceeding sample holding times for 

constituents and physical properties listed in table 4 were 

not evaluated. Any data exceeding standard laboratoryrecommended holding times were flagged by the laboratory 

with the appropriate information.

During sample retrieval, sample-retrieval sheets 

(Appendix 1) and/or miscellaneous-note sheets (Appendix 

2) were completed. The sample-retrieval sheets included 

information regarding field or runoff conditions, field 

observations, ISCO sampler dates and times, sample bottle 

labeling, nitrogen system status, bottle fill volumes, CSG 

readings, and selected datalogger information. If samples 

were retrieved during runoff, the staff-gage reading in the 

H flume and the stage output by the datalogger program 

also were recorded. These comparisons helped to indicate 

whether the pressure transducer and nitrogen system were 

accurately measuring actual H-flume stage. If discrepancies were found between the two readings, the recorded 

field data were used to correct the datalogger stage and 

discharge record accordingly.

Sample Collection for Quality Assurance and Quality 

Control

It was essential that the data collected were of known 

and acceptable quality to support the data analyses planned 

for the project. The WWSC used a quality-assurance (QA) 

plan (Richards and others, 2006) that addressed waterquality data for all projects including Discovery Farms 

and Pioneer Farm. Using the guidelines of this plan, field 

blanks and cross-section coefficient samples were scheduled for collection at all Discovery Farms and Pioneer 

Farm stations. These samples helped determine precision 

and accuracy between the automatic samples as well as 

how representative the automated samples were of the 

“true” constituent concentrations in the water column. The 

goal was that approximately 10 percent of the total number 

of samples submitted would be quality-control (QC) 

samples.
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 23

Field Blanks

Field blanks were used to determine whether contamination was introduced by the entire sampling process, 

including the autosampler equipment (sample-intake line 

and sample bottles) and sample-processing procedures 

(churn splitting, filtering, and use of laboratory-analysis 

bottles). The procedures used to collect field blanks were 

similar to those documented in the WWSC QA plan; 

however, type 1 reagent-grade water was not used because 

results to date have shown that this level of accuracy 

was unnecessary for the project needs. Rather, deionized 

water produced in the WWSC field office was used for 

field blanks. Samples of the deionized blank water were 

periodically analyzed for all constituents and properties 

determined for runoff samples. If field-blank constituent 

concentrations were consistently of the same magnitude or 

greater than concentrations in runoff samples, an evaluation of sampling equipment and process was done to 

determine the source of contamination. Field blanks were 

collected once per year at each station for Discovery Farms 

and Pioneer Farm; however, field blank collection started 

in 2006 at the Pioneer Farm stations.

Cross-Section Coefficient Samples

To determine whether constituent concentrations in 

the automatic, discrete samples (which were pumped from 

a single point at the tip of the sample-intake line) were 

representative of the constituent concentrations in the cross 

section of the water column, concurrent-replicate samples 

(also termed cross-section coefficient samples) were collected: one manually and one pumped by the automatic 

sampler. The WWSC QA Plan calls for collection of a 

manual sample by either the equal-width-increment (EWI) 

or equal-distance-measurement (EDI) method; however, 

it was usually too shallow to accurately collect a sample 

using these methods. Rather, a 1-liter polypropylene bottle 

was placed into the flow stream (grabbed) at the throat 

(exit) of the H flume as it cascaded to the ground below. 

This method collected water from the narrowest point of 

flow, so the chances of obtaining representative samples 

were likely the highest here. Immediately after the manual 

sample was collected, the automatic sampler was triggered 

to pump a single, discrete sample using the same rinse and 

purge cycle used for standard runoff-event samples. Both 

samples were analyzed as discrete samples, and no splitting of the samples was required. Cross-section coefficient 

samples were scheduled for collection at least once per 

year at all Discovery Farms stations.

Analytical results of QC samples were inspected 

immediately upon receipt to identify any problems with 

sample collection, handling, or analysis. If constituent 

concentrations in blank samples were consistently greater 

than or equal to runoff-event sample concentrations, or if 

cross-section coefficient samples were not closely comparable to each other, the reporting laboratory was contacted 

to check for errors in data reporting. If sample water was 

still available at the laboratory, reanalysis was sometimes 

requested. If the problem was not found at the laboratory, a 

systematic process was used to determine the causes of the 

contamination. The most common contamination was due 

to the technique used to collect blank samples. The technique was slightly modified over time to ensure that blank 

water was properly purged through all sampling equipment 

during the rinse cycle.

Maintenance

Maintenance was vital to accurately measure the 

quantity and quality of surface-water runoff from edge-offield stations. During spring, summer, and fall, stations were 

periodically maintained by mowing around the enclosure 

and along the wingwall. This was done to ensure easy 

access around the enclosure as well as to allow inspection of 

the wingwall. Flumes were surveyed at least twice per year 

to determine whether adjustments to the stage-discharge 

relation were necessary. Maintaining fuel levels for stations 

with generators was also a part of station maintenance.

More maintenance was needed at edge-of-field stations during winter than for the rest of the year. During 

winter, snow and ice could fill the H flume and downstream channel, causing backwater conditions if runoff 

had occurred. In addition, ice in the flume could cause the 

bubble tubing and the sample-intake line to freeze, causing erroneously high stage measurements and preventing 

samples from being pumped. 

Frequent visits were necessary to remove ice and 

snow prior to anticipated surface-water runoff events. 

Ice was generally removed by carefully breaking it into 

smaller pieces with a hammer. Portable clothing steamers also were used to cut through ice that was particularly 

thick. In most cases, snow was removed from the H flume, 

and a trench was dug in the snow upstream and downstream from the H flume (fig. 15). The trench upstream 

from the H flume prevented surface-water runoff from 

flowing on top of the snow and cascading into the H flume, 

causing erroneous stage readings because of turbulence. 

The trench downstream from the H flume was cleared to a 

point where the flume would be free of backwater.
24 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Numerous attempts were made to reduce maintenance 

required by the ice formation in the H flumes. Most were 

relatively ineffective. Development of better ice-preventative systems is still being researched; however, there was 

no substitute for frequent station visits for proper maintenance.

The first four H flumes for edge-of-field stations at 

Pioneer Farm were ordered with a standard white finish. All newer flumes for Pioneer Farm and all Discovery 

Farms flumes were ordered with a dark-green finish. On 

sunny days, the dark color of the H flume helped to absorb 

solar energy, thus melting ice within the flume, or at least 

making ice less likely to attach securely to the flume, making it easier to clear the flume of ice.

Plywood and clear acrylic covers were built over 

the flumes to try to prevent snow buildup and to trap heat 

within the flume. These methods generally did not work 

well, because snow became trapped and accumulated in 

the H flume underneath the covers. The acrylic covers 

were brittle in cold weather and broke easily. Rubber flaps 

were added to minimize the snow buildup, but they often 

froze to the ground in ice that formed in front of the flume. 

Propane heaters were hung in the H flumes to prevent ice 

from forming. The propane heaters were difficult to keep 

operating because wind would blow out the pilot light.

Infrared heat lamps were also used to prevent ice 

formation. The lamps melted the ice directly below the 

lamp, but power had to remain on constantly to prevent 

ice from reforming. The constant power necessary was 

only available at AC-powered stations. Also, the heat lamp 

bulbs had a tendency to break in below-freezing conditions.

Tents were erected to cover the H flume and a short 

distance upstream and downstream from the flume to 

prevent ice formation at some Pioneer Farm stations. 

Directional propane heaters were used in conjunction with 

the tents to prevent freezing. This method was successful 

but required much maintenance. If ice formed within the 

tents, it was difficult to remove because of limited working 

space.

Heat tape was placed within the H flume at most 

edge-of-field stations to reduce or prevent ice that formed 

near the bubble tubing, sample-intake-line tip, and flume 

exit. The heat tape was attached to the floor of the H flume 

near the sample-intake line and bubble tubing, and exited 

out of the downstream side of the flume. The heat tape was 

Time-lapse

camera and enclosure

Aluminum

enclosure

Plywood

wingwall

Crest-stage

gage

H flume

A/C

power

pedestal

Direction of flow

Figure 15. Snow was cleared downstream from the flume to prevent backwater conditions. Wintertime maintenance was 

essential to collecting accurate data. 
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 25

somewhat effective, provided that it could be constantly 

powered. Although the heat tape did not totally prevent ice 

buildup in the flumes, it was effective at reducing water 

freezing in the tip of the sample-intake line and bubble 

tubing and reduced freezing of water in the exit of the 

flume.

Streamgaging Stations

Equipment

There were six streamgaging stations ranging in 

contributing basin size from 215 to 1,882 acres in the 

Discovery Farms and Pioneer Farm programs. Discovery 

Farms streamgaging stations used H flumes to compute 

discharge, whereas the streamgaging stations at Pioneer 

Farm used standard, measurement-based stage-discharge 

techniques to compute discharge. Equipment similar to 

that used for edge-of-field stations was used for stage 

measurement, sampling, data capture, measurement and 

control, communication, and power: Sutron Accubar 

nonsubmersible pressure transducers were used to monitor stage, refrigerated ISCO samplers were used to collect 

water samples, and Campbell Scientific, Inc. CR10 or 

CR10X dataloggers were used for data capture and program control. Communication was established by either 

telephone modem and/or wireless telemetry, and electrical 

power was provided by AC, generator, or solar power. The 

primary difference between equipment used for streamgaging stations and edge-of-field stations was that the 

Discovery Farms streamgaging stations used interlocking, 

2-foot-wide, 8-gage steel sheet piling for wingwalls, rather 

than plywood. In addition, the Discovery Farms streamgaging stations used thermocouple wire to measure water 

temperature.

Discovery Farms

Like edge-of-field stations, streamgaging stations 

monitored for the Discovery Farms program used H flumes 

for the continuous determination of discharge (fig. 16). 

The H flumes were connected to a wingwall constructed 

of steel sheet piling that was driven to the point of refusal 

into the stream bottom and banks. The use of sheet piling 

helped to prevent water from undercutting the flume and 

provided strength to prevent failure during periods of high 

discharge.

The bubble tubing for stage measurements in two of 

the streamgaging flumes was located within 6-inch-diameter stilling wells rather than on the flume floor. Monitoring stage in stilling wells was thought to be advantageous 

in that stage measurements would be protected from high 

stream velocities that could create a drawdown effect, 

causing stage measurements to read erroneously low. However, sediment occasionally filled in the stilling well, causing erroneously high stage readings. In addition, numerous 

comparisons of staff-gage measurements to those recorded 

by the dataloggers showed that drawdown was insignificant in H flumes where the bubble tubing was attached to 

the flume floor—even for high discharges. Access to the 

bubble tubing in a stilling well for maintenance was also 

more difficult.

The location of the sample-intake line tubing in the 

streamgaging H flumes was similar to that for edge-offield stations—near the flume exit—but the sample tubing 

was approximately 1 inch above the flume floor to prevent 

bedload material from being pumped into the sample 

bottles.

Pioneer Farm

At Pioneer Farm, two streamgaging stations were 

located in an upstream/downstream configuration. Unlike 

edge-of-field stations at the farm, H flumes were not used 

to estimate discharge. Rather, continuous discharge was 

estimated from continuous open-channel stage measurements according to standard USGS methods after defining 

a stage-discharge relation within the stream channel (fig. 

17; Buchanan and Somers, 1969; Rantz, 1982). Instantaneous discharge measurements for use in the rating were 

made approximately every 3 weeks and more frequently 

during high discharges.

Station

enclosure

Earthen

berm

Sheet piling

wingwalls

H flume 

Figure 16. Sheet piling and earthen berms were used as 

wingwalls for the streamgaging stations at Discovery Farms.
26 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Sample Collection

Sample Collection and Pickup for Runoff Events

Sample collection and pickup during periods of 

runoff for streamgaging stations was similar to that at 

edge-of-field stations for Pioneer Farm and for the Iowa 

County Discovery Farm. Runoff-event samples collected 

by the ISCO samplers were generally retrieved within 24 

hours of the end of a runoff event. At that time, sampleretrieval sheets and/or miscellaneous-note sheets were 

filled out (Appendixes 1 and 2), and staff-gage readings 

in the H flumes and the corresponding stages recorded by 

the datalogger were noted. Samples were removed from 

the ISCO samplers, labeled, placed in coolers with ice, 

and then transported to the WEAL for analysis. Samples 

for streamgaging stations were typically received by the 

laboratory within 3 days of a runoff event. Several trips to 

pick up and deliver samples were typically made for runoff 

periods that lasted more than 2 days. Occasionally, some 

samples were not received by the laboratory for 4 days or 

more from the time the first sample was collected.

Stage data were recorded by the datalogger at 15- or 

60-minute intervals during base-flow conditions. The datarecording frequency increased to 1 minute or 5 minutes 

when the stage exceeded the data threshold, which was 

generally within 0.1 to 0.2 foot above the pre-event baseflow stage. The sampling threshold was set equal to or 

slightly greater than this stage. Sampling ended when the 

stage receded below the sampling threshold.

Sample collection at Buffalo County farm streamgaging stations differed from that at the stations described 

above. This was the first farm established for the Discovery Farms program, and the samples were sent to 

the Wisconsin State Laboratory of Hygiene in Madison, 

Wis. (WSLH). The WSLH did not do any splitting of the 

samples to produce the single composite sample for each 

surface-water runoff event, so volume-paced event samples 

were collected by use of the ISCO sampler. Two discrete 

subsamples were collected per bottle, allowing a maximum 

of 48 samples per runoff event. The accumulated-discharge 

and the sample-threshold variables were adjusted for each 

runoff event based on anticipated precipitation amounts 

and intensities, antecedent moisture conditions, and season. Accumulated discharge between samples was occasionally adjusted during runoff events to maximize sample 

coverage without exceeding sampler capacity.

Buffalo County farm samples were usually retrieved 

within 24 hours of the end of sampling a runoff event. The 

sample bottles were labeled and placed in a cooler with ice 

for transportation back to the USGS WWSC for processing. Several trips to pick up and deliver samples were typically made for runoff events that lasted more than 2 days. 

The samples were split and a single composite sample was 

sent to the WSLH for analysis for each runoff event.

Sample Collection during Base Flow

Base-flow samples for the Discovery Farms program 

were collected once per month and delivered to the WEAL 

(for samples from Iowa County streamgaging stations) or 

the WSLH (for samples from Buffalo County streamgaging stations) for analysis. Samples were collected when it 

was assumed that there was no overland flow component 

to streamflow. Each sample was assumed to represent the 

constituent concentrations for the base-flow component 

of streamflow for that month. The base-flow sample was 

a grab sample, collected in a 1-liter polypropylene ISCO 

bottle from the exit section of the flume. For the Pioneer 

Farm program, stream base-flow samples were collected 

every 2 weeks by triggering a sample with the ISCO sampler.

Maintenance

Streamgaging stations required periodic maintenance. 

During summer, algae growth in the flume and inside the 

tip of the bubble tubing occasionally caused erroneously 

high stage readings. Sediment was sometimes deposited in 

the flume during runoff events. Station visits were made to 

purge the tubing of algae and to clear algae and sediment 

from the flume. At flume locations with stilling wells, the 

stilling wells were periodically flushed with clean water to 

Figure 17. U.S. Geological Survey field technician making a 

discharge measurement at a streamgaging station at Pioneer 

Farm.
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 27

remove sediment that accumulated in the bottom. Streamgaging stations with flumes were surveyed at least twice 

per year to determine whether adjustments to the stagedischarge relation were necessary. Staff-gage readings in 

the H flume were also compared to stages recorded by the 

datalogger to check for accuracy.

During winter, ice sometimes formed in the stream 

channel and in the H flumes. During station visits, ice was 

removed from the flumes similarly to the methods used for 

edge-of-field stations. Ice in the stream channel could not 

be prevented and was not easily removable, so discharge 

measurements were made during ice-affected periods to 

determine the degree of backwater and to develop a stagedischarge relation to account for these conditions.

Subsurface-Tile Stations

Equipment

There were five subsurface-tile stations for the Discovery Farms program ranging in contributing basin size 

from 13.2 to 641 acres. Equipment similar to that used for 

streamgaging stations was used for stage measurement, 

sampling, data capture, measurement and control, communication, and power: Sutron Accubar nonsubmersible pressure transducers were used to monitor stage, refrigerated 

ISCO samplers were used to collect water samples, thermocouple wire was used to measure water temperature, 

and Campbell Scientific, Inc.CR10 or CR10X dataloggers 

were used for data capture and program control. Communication was established by either telephone modem and/

or wireless telemetry, and electrical power was supplied 

either by AC, generator, or solar power. The primary 

equipment difference between edge-of-field, streamgaging, 

and subsurface-tile stations was the type of flume used to 

compute discharge. Subsurface-tile stations were located 

both within fields and at subsurface-tile outlets.

Subsurface Tiles within Fields

Monitoring was done at three subsurface tiles within 

fields. The two monitored tiles in Kewaunee County (table 

1, fig. 19) were made of clay and were 6 inches in diameter; the tile monitored in Manitowoc (table 1, fig. 18) was 

concrete and was 12 inches in diameter. All three in-field 

tiles were approximately 3 feet below the land surface, 

beneath grassed waterways.

A backhoe was used to create a 10-foot-deep hole 

that bisected the subsurface tile at the desired monitoring 

location. The hole was then backfilled with several feet 

of 2-inch rock, and a 10-foot-long, 5-foot-diameter round 

plastic culvert with cover was placed vertically on top of 

this rock, leaving approximately 2 feet of the culvert above 

ground. A 4-foot-deep trench was dug approximately 10 

feet upstream and downstream from the monitoring location to break and remove sections of the existing tile. The 

existing tile was then replaced with a similar diameter 

20-foot-long piece of polyvinyl chloride (PVC) sewer pipe 

that was routed through holes cut in the culvert (fig. 18). 

The culvert was then backfilled with 2-inch rock to a level 

approximately 2 feet below the PVC pipe to allow water 

storage, and the remaining trench was backfilled with the 

excavated soil.

Either “extra-large,” 60-degree, v-throat, trapezoidal 

flumes or 2-inch (throat width), 45-degree Washington 

State College trapezoidal flumes were installed in line 

with the PVC pipe within the vertical 5-foot-diameter 

culvert (fig. 19). Trapezoidal flumes were used to compute 

discharge in subsurface tiles at all three of these stations. 

These flumes were chosen because of their ability to accurately measure low discharges, and their cross-sectional 

shape was conducive to placement in line with subsurface 

tiles.

Figure 18. A 5-foot-diameter culvert was installed to allow 

access to in-field subsurface tiles.
28 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

To install the flume, treated plywood was attached to 

both ends of the flume and a hole was cut in the plywood 

to receive two short pieces of the PVC pipe. The flume, 

plywood, and short PVC pieces were then attached to 

the inline PVC pipe by means of rubber gaskets. The 

flume was supported using pieces of rebar driven into the 

backfilled rock and soil. Care was taken to ensure that the 

flume was level from side to side and was set with a slight 

drop toward the downstream side (consistent with the 

existing tile slope). Field measurements indicated that the 

trapezoidal flumes were sensitive to front-to-back slope, 

so the slope was measured and the discharge was corrected accordingly during data analysis. Bubble tubing for 

measuring stage was connected to the floor of the flume 

near the staff gage (the upstream side). The sample-intake 

line was positioned approximately 1⁄4 inch above the flume 

floor near the bubble tubing.

Subsurface Tiles at Outlets

Monitoring was done at the outlets of two 6-inch 

PVC subsurface tiles in Waukesha County. Extra-large, 

60-degree, v-throat, trapezoidal flumes were used to 

compute discharge (fig. 20). The flumes were attached to 

the outlet of existing tile using the same materials as the 

in-field subsurface-tile stations and were supported with 

rebar. Treated plywood boxes with insulated covers were 

constructed around the flumes to prevent snow and other 

debris from clogging them. Bubble tubing and sampleintake lines were attached as for the in-field subsurface-tile 

stations.

Sample Collection

Time-paced samples were collected at in-field and 

subsurface-tile outlet stations. At the time of this study, 

changes in constituent concentrations in the monitored 

subsurface tiles were not well understood. Also, some of 

the monitored subsurface tiles were observed to flow for 

most of the year and, generally, stop flowing only during 

particularly dry periods. In order to fully characterize the 

dynamics of constituent concentrations found in these tiles, 

water was sampled at representative intervals during runoff. Increases in discharge due to precipitation or snowmelt 

events were sampled more frequently (minutes to hours) 

than were the lengthy recession periods (hours to days). 

Monthly samples were adequate to describe base-flow 

periods in streams, because the source of water in streams 

(ground water) usually had relatively consistent constituent 

Figure 19. Extra-large, 60-degree, v-throat, trapezoidal flumes were installed inline with 

discharge.

subsurface tiles within fields to compute 
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 29

concentrations. In subsurface tiles, however, the source of 

water during the recession—and the associated constituent variability—was unknown, and therefore a higher 

sampling frequency for base-flow periods was required 

until the systems were better understood. If a particular 

subsurface-tile station was found to have consistent concentrations during base flow, a lower sampling frequency 

was eventually used.

Stage data were recorded by the datalogger at 15-minute intervals during zero-flow or low-flow conditions. The 

data recording frequency increased to 5 minutes when the 

stage exceeded the data threshold, which was generally 

within a few hundredths of a foot above the point of zero 

flow. When the tile was flowing, the sample threshold was 

set at about 0.1 foot higher than the pre-event stage. When 

the tile was not flowing, the sampling threshold was usually set a few hundredths of a foot above the data threshold 

so that samples were collected shortly after event runoff 

began. Sampling ended when the stage receded below the 

sampling threshold.

Runoff-event samples collected by the ISCO samplers 

were generally retrieved within 24 hours of the end of a 

runoff event. At that time, sample-retrieval sheets and/

or miscellaneous-note sheets were filled out (Appendixes 

1 and 2), and staff-gage readings in the H flumes and the 

corresponding stages recorded by the datalogger were 

noted. Samples were removed from the ISCO samplers, 

labeled, placed in coolers with ice, and then transported 

to the WEAL for analysis. Samples for subsurface-tile 

stations were typically received by the laboratory within 3 

days of a runoff event. Several trips to pick up and deliver 

samples were typically made for runoff periods that lasted 

for more than 4 days. Occasionally, some samples were 

not received by the laboratory for a week or more from the 

time the first sample was collected.

Maintenance

Subsurface-tile stations were generally maintained 

much like the edge-of-field stations, with periodic mowing 

and inspection in summer. The in-field subsurface-tile stations did not freeze in winter, so maintenance was similar 

to that in other seasons. The subsurface-tile outlet stations did occasionally freeze during winter. Heat tape was 

placed along the sample-intake lines and bubble tubing to 

prevent them from freezing.

Figure 20. Extra-large, 60-degree, v-throat, trapezoidal flumes were used to compute discharge at the outlets of subsurface 

tiles. The insulated plywood cover was removed for this photo.
30 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Meteorological Stations

Equipment

Meteorological stations were installed at five of the 

seven Discovery Farms and at Pioneer Farm (fig. 21). Each 

meteorological station recorded precipitation, wind speed, 

wind direction, air temperature, relative humidity, solar 

radiation, soil temperatures (at 2, 5, 10, 20, 40, and 80 centimeters depth), and soil moisture (30-centimeter average 

and/or at 10, 20, 30, and 50 centimeters depth). A detailed 

listing of manufacturers and equipment names can be 

found in table 6. Each station was also equipped to allow 

remote communication via wireless or phone telemetry.

Wind speed and direction, air temperature and relative 

humidity, and solar radiation instruments were attached 

to a 20-foot aluminum tower at approximately 20 feet, 6 

feet, and 7 feet above ground level, respectively. The tower 

was located on a hill and/or away from buildings and trees 

on the monitored farm. In some cases, a taller tower was 

installed to enable or improve wireless communication.

Soil temperature probes were installed by means 

of a strip of treated wood with small holes drilled at the 

appropriate depths. The probes were inserted through the 

holes and secured with wire ties (fig. 22). A 4- to 6-inchdiameter vertical hole was dug in the soil and the wood 

and probes were placed into the hole, pushed horizontally 

into the undisturbed soil profile; the hole was then carefully backfilled.

Two types of soil-moisture probes were usually 

used at each location: the Campbell Scientific, Inc.

model CS616 and the Sentek EasyAg probe. The CS616 

was inserted into the ground vertically and, as installed, 

measured the average soil moisture content of the top 30 

centimeters of soil. The EasyAg was installed vertically 

by use of product-specific installation tools. Soil-moisture 

values for the EasyAg were measured at 10-, 20-, 30-, and 

50-centimeter depths.

Tipping-bucket precipitation gages (0.01 inch per 

tip) were installed on either a 6-inch round wooden post 

or 2-inch galvanized pipe. The post or pipe was driven 

3–4 feet into the ground, and the precipitation gage was 

attached to the top and leveled. The top of the precipitation 

gage was typically 7 feet off the ground and away from 

overhead obstructions. The precipitation gages were used 

to quantify all unfrozen precipitation.

Meteorological data were recorded on a Campbell 

Scientific, Inc.CR10 or CR10X datalogger. A Campbell Scientific, Inc.COM 210 telephone modem and/or 

Campbell Scientific, Inc.RF400 radio/modem were used 

for remote communication. Equipment at the station was 

powered by a 12 volt, 8-ampere-hour battery charged by 

a 10-watt solar panel. All datalogger and communication 

instrumentation was contained in a fiberglass enclosure 

mounted to the tower.

Maintenance

Maintenance was minimal at meteorological stations. 

During the growing season, grass was trimmed around 

the base of the station tower. During this time, equipment 

was visually inspected. The tipping-bucket precipitation 

gages were checked for levelness and cleaned periodically 

throughout the year. Calibrations were done at least once 

per year to ensure accuracy.

Table 6. Equipment used for collection of meteorological data. 

[Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.]

Instrument type Manufacturer Instrument name

Wind speed and direction Met One Instruments, Inc. 034B windset

Air temperature and relative humidity Vaisala 50Y temperature/RH probe with solar radiation shield

Solar radiation LI-COR Biosciences. Inc. LI200x pyranometer

Soil temperature Campbell Scientific Inc. 107 temperature probe

Soil moisture Sentek Sensor Technologies EasyAg

Soil moisture Campbell Scientific, Inc. CS615, CS616

Precipitation Design Analysis Associates H340SDI Tipping-bucket Rain Gage
Data Collection for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 31

Precipitation

gage

Solar

panel

Instrumentation

enclosure

Wind speed and

direction sensors

20-foot aluminum tower

Solar radiation

sensor

Air temperature and relative

humidity sensors deployed

in radiation shield

Figure 21. Meteorological station equipment typically measured precipitation, wind speed and direction, air and soil 

temperature (in profile), relative humidity, solar radiation, and soil moisture (in profile).
32 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Sample Processing for Edgeof-Field, Streamgaging, and 

Subsurface-Tile Stations

Water-quantity and water-quality data generated for 

each runoff event were subjected to a series of office and 

laboratory processes that required consideration of two 

issues: which samples were to be combined to form a composite sample, and how the samples were to be combined. 

Samples were processed one of two ways as described 

below. Both processes were designed to provide a sample 

for laboratory analysis that represented the water conditions for that sampled period.

Sample Processing for Samples Sent to 

the Water and Environmental Analysis 

Laboratory

Numerous time-paced, 1-liter discrete samples were 

collected for each runoff event. Analyzing each discrete 

sample was cost prohibitive and more than was needed to 

meet the objectives of the Discovery Farms and Pioneer 

Farm programs. Rather, a single, composite sample that 

represented the mean discharge-weighted concentration for 

each runoff event was produced. This composite sample 

was produced from discharge-weighted portions of every 

discrete sample collected.

Prior to sample analyses, a “splitting record” was 

developed for each runoff event to help prepare the composite sample (Appendix 3). The constituent concentrations from this sample were multiplied by the runoff-event 

volume to estimate an event load.

Splitting Records

A splitting record was a spreadsheet generated from 

detailed time-series data for stage, discharge, precipitation, 

and selected sample information for each runoff event. A 

portion of this splitting record, the “summary” (fig. 23), 

was emailed to the WEAL to provide information on how 

the samples were labeled during pickup, when samples 

were picked up, sample dates and times, which discrete 

samples were to be combined for a particular composite 

sample, the volumes of each sample that should be used to 

create the composite sample, and other pertinent information.

Computations within the splitting record worksheet 

were based on the assumption that each discrete sample 

collected during a runoff event represented average constituent concentrations in runoff water that had passed through 

the flume from the time halfway between a sample and the 

sample before and after it. Based on this assumption, the 

runoff volume that each discrete sample represented was 

calculated by summing the time-series discharge values for 

the appropriate time periods. Each discrete sample-runoff 

volume was then multiplied by the maximum amount of 

water to be removed from each sample bottle and then 

divided by the maximum discrete sample-runoff volume 

(of all the discrete samples to be included in the composite 

sample). The maximum amount of water to be removed 

from each sample bottle was then adjusted so that the total 

volume of the composite sample did not exceed 4 liters 

(slightly less than the churn capacity). These calculations 

determined the appropriate volume of water to be removed 

from each discrete sample (aliquot) to be combined to create a discharge-weighted composite sample. By use of this 

Figure 22. Soil-temperature probes ready for installation.
Sample Processing for Edge-of-Field, Streamgaging, and Subsurface-Tile Stations 33

technique, the discrete samples representing the highest 

amounts of runoff volume had the highest volume of water 

represented in the composite sample, whereas the discrete samples representing the smallest amounts of runoff 

volume had the smallest amounts of water represented in 

the composite sample. The result of combining discrete 

samples in this manner was the creation of a dischargeweighted composite sample in which constituent analyses 

represented the event-mean concentration for a runoff 

event.

Edge-of-Field Stations

Splitting records for edge-of-field stations were typically created within 1 week after the end of a runoff event 

and subsequent sample collection in order to expedite the 

preparation and preservation of samples. Consequently, 

“raw” stage or discharge data from the datalogger was 

often used to produce the splitting record. Minor corrections that may have been required were done at a later 

time. Major corrections that would significantly affect 

the runoff-event volumes (and thus the volumes of each 

discrete sample necessary to create the composite sample) 

were made before producing the splitting record.

Runoff generally did not occur between events for 

edge-of-field stations; therefore, start and end times were 

usually based on when surface-water runoff began and 

ended. However, determining the runoff event start and 

end times from the “raw” data was sometimes difficult 

because low stages were particularly “noisy” due to wind, 

ice, debris, or sedimentation. In addition, splitting records 

were sometimes created before water stopped flowing 

completely. To ensure reasonably accurate volumes during 

the splitting-record process, start times were assumed to 

occur when the flume stage increased to 0.05 foot and end 

times were assumed to occur when stages subsided below 

0.05 foot. This stage was chosen because the volume of 

water passing through the flume was minimal and stages 

above this were usually accurate with minor corrections 

only occasionally necessary. 

During events that had multiple distinct peaks, start 

and end times were based on the minimum stage between 

peaks. For example, snowmelt events commonly lasted 

several days, with daytime peaks and nighttime recessions. Occasionally, discharge would continue to decrease 

throughout the night and then increase again with warmer 

temperatures the next day. In these cases, the end time of 

an event was assumed to occur at the same time the next 

event started; when the stage just started to increase. Usually, this was at the minimum stage between peaks. 

Streamgaging Stations

Unlike edge-of-field stations, the monitored streams 

had continuous discharge; consequently, a base-flow 

component of streamflow needed to be accounted for 

when determining the start and end times of runoff events. 

The event start was defined as the time when the stage or 

discharge hydrograph began to increase above base flow. 

Because the recession limb of stream-runoff events was 

Runoff Event ID

KP2-4a 03/07/06 13:15 03/10/06 9:10

KP2-4a-2 03/08/06 20:00 31

KP2-4a-3 03/08/06 22:10 347

KP2-4a-4 03/09/06 00:10 363

KP2-4a-5 03/09/06 02:10 284

KP2-4a-6 03/09/06 04:10 234

KP2-4a-7 03/09/06 06:10 209

KP2-4a-8 03/09/06 08:10 287

KP2-4a-9 03/09/06 12:10 410

KP2-4a-10 03/09/06 16:10 423

KP2-4a-11 03/09/06 20:10 397

KP2-4a-12 03/10/06 00:10 355

KP2-4a-13 03/10/06 04:10 500

Bottles KP2-1 through KP2-8 picked up on 3/9/06

Bottles KP2-9 through KP2-13 picked up on 3/11/06

Use bottle KP2-1 as a discrete sample: 2/27/06 @ 16:15

Runoff Start Runoff End

Discrete sa

mple IDs and tim

e

of

collection

Volu

m

e

of e

ach sa

m

ple to

b

e

use

d for co

m

p

osite sa

m

ple (ml)

Figure 23. Example of a splitting record summary showing which samples to combine and the proper aliquot sizes to create a 

discharge-weighted composite sample.
34 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

generally prolonged and blended into the base flow, determination of the true end of an event was somewhat subjective. For the Discovery Farms and Pioneer Farm programs, 

the end of a stream-runoff event was defined as the time 

when there was no overland flow and a minimal bank-storage component to streamflow. Although there were several 

methods to determine this time (Linsley and others, 1982), 

a technique that yielded consistent results was a simple, 

graphical approach. First, the event hydrograph (stage or 

discharge) was plotted on paper. A line (line 1) was drawn 

on the right-hand end of the recession plot starting 6 hours 

or more after overland flow was assumed to have stopped 

(fig. 24). Where line 1 started to diverge from the recession plot, line 2 was drawn along the slope of the previous 

part of the recession. The event end was then defined as 

the time when line 2 started to diverge from the recession 

plot. After determining the event start and end, a splitting 

record was produced in a manner similar to that used for 

edge-of-field stations. Discrete samples collected after the 

event were discarded. Like edge-of-field stations, start and 

end times for multiple-peak events were based on the minimum stage between peaks.

Subsurface-Tile Stations

Event start and end times were determined for subsurface-tile stations in a manner similar to that for streamgaging stations. The event start was defined as the time 

when the stage or discharge hydrograph began to increase. 

For some subsurface-tile stations, hydrograph recessions 

were similar to those for streams, and the same graphical 

method was used to determine event-end times. At other 

subsurface-tile stations, hydrograph recessions were not 

well defined and were prolonged (days to weeks), and the 

graphical approach was not useful or practical. For these 

stations, event-end times were usually determined by visible changes in hydrograph shape. When no shape change 

was obvious, event-end times were determined based on 

when samples were collected so that holding times were 

minimized. Like edge-of-field and streamgaging stations, 

start and end times for multiple-peak events were based on 

the minimum stage between peaks.

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

12/31/04 20:0012/31/04 22:001/1/05 0:001/1/05 2:001/1/05 4:001/1/05 6:001/1/05 8:001/1/05 10:001/1/05 12:001/1/05 14:001/1/05 16:001/1/05 18:001/1/05 20:001/1/05 22:001/2/05 0:001/2/05 2:001/2/05 4:001/2/05 6:001/2/05 8:001/2/05 10:001/2/05 12:001/2/05 14:001/2/05 16:001/2/05 18:001/2/05 20:001/2/05 22:001/3/05 0:001/3/05 2:001/3/05 4:001/3/05 6:001/3/05 8:001/3/05 10:001/3/05 12:001/3/05 14:001/3/05 16:001/3/05 18:001/3/05 20:001/3/05 22:001/4/05 0:001/4/05 2:001/4/05 4:001/4/05 6:001/4/05 8:001/4/05 10:001/4/05 12:001/4/05 14:001/4/05 16:00

STAGE IN FEET

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

STORM RAIN IN INCHES

Original CR10 stage

Sample time

Rainfall

Event end: at time when line 

2 diverges from hydrograph

Event start: at time when 

hydrograph begins to rise 

above baseflow

Line 1

Line 2

Figure 24. Example hydrograph showing the method used for determining the start and end of a runoff event at a streamgaging 

station.
Sample Processing for Edge-of-Field, Streamgaging, and Subsurface-Tile Stations 35

Laboratory Procedures

Discrete samples that arrived at the WEAL were 

organized by station and date and were placed in a walkin cooler at 4oC. Once the splitting-record summary 

was received by the laboratory, the sample bottles were 

removed from the cooler and arranged in order. Each 

sample set was labeled with station name, event number, 

sample number, and sample date. The bottles were then 

shaken vigorously, and a photograph was taken while any 

suspended materials were still in suspension (fig. 25). The 

photograph was used as a visual reference to the runoff 

event to help explain variability in constituent concentrations.

Splitting Procedures

Once the discrete samples were organized, the 

splitting-record summary was used to combine the appropriate aliquots from each of the discrete samples to make 

the composite sample. Each sample bottle was shaken 

vigorously prior to being poured into a 4.5-liter polyethylene churn splitter. The lid was placed on the churn 

and locked in place, and a pneumatic arm attached to the 

paddle shaft was activated to properly agitate the sample 

by moving the churn paddle at a rate greater than 9 vertical 

inches per second. The sample was agitated for at least 30 

seconds before the aliquot was dispensed (according to the 

splitting-record summary and within +/-10 milliliters) into 

a glass graduated cylinder. The aliquot was then poured 

into a 1-liter polyethylene bottle. The churn and graduated 

cylinder were not rinsed between samples within the same 

set but were triple rinsed with reverse-osmosis (RO) water 

between samples from different stations. Aliquots from 

subsequent discrete samples were poured into the same 

1-liter bottle until the bottle was full, then a separate 1-liter 

bottle was used, and so forth.

After the appropriate aliquots had been taken out of 

each of the discrete samples, up to 4 liters (four 1-liter 

bottles) of sample water was available to make the composite sample. Water from these bottle(s) was poured back 

into a churn where it was again agitated for at least 30 

seconds before laboratory-analysis bottles were filled with 

the final, composite-sample water.

Filtering

Composite samples were filtered by first placing 

them into a clean, polyethylene transfer bottle. Samples 

were filtered using a filter cassette containing a 47-millimeter-diameter mixed-cellulose ester membrane with a 

0.45-micrometer pore size and a 934-AH or GD 1-microFigure 25. Photographs were taken of each set of water-quality sample bottles prior to compositing.
36 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

meter prefilter connected to a syringe. Approximately 

10 milliliters of the composite sample was poured from 

the transfer bottle into the syringe. The syringe was then 

rolled to allow the composite sample to rinse the syringe 

and filtering cassette until it was slowly poured out. More 

composite-sample water was added to the syringe, then 

10 to 20 milliliters was filtered through the cassette and 

discarded. The remainder of the composite sample was filtered through the cassette into a laboratory-analysis bottle. 

For samples that contained large amounts of suspended 

solids or organic material, suspended particles were 

allowed to settle before rinsing and filtering. For these 

samples, a GD1 multi-grade prefilter was used instead of 

the 934-AH glass-fiber prefilter.

Sample Processing for Samples Sent to the 

Wisconsin State Laboratory of Hygiene

Different sample-processing procedures were necessary for the Buffalo County streamgaging stations because 

samples were analyzed at the WSLH and discrete samples 

were collected on a volume-paced basis. Because this technique was chosen, a splitting record was not needed. The 

WSLH did not prepare or split samples in a manner similar 

to that at the WEAL, so samples were split into the proper 

laboratory-analysis bottles and preserved appropriately 

before arrival at the WSLH.

Runoff event start and end times were determined as 

defined previously. Once these times were determined, the 

discrete sample times were examined to determine which 

samples should be used to create the composite sample. If 

sampling for a runoff event stopped before the end of the 

runoff event, all of the samples were kept for the composite sample. If sampling continued past the end of the runoff 

event, the extra samples were discarded. If the end time 

of the runoff event occurred between two samples that 

were in the same bottle (two samples were collected per 

1-liter bottle at the Buffalo County streamgaging stations), 

then one-half of the last bottle was used for the composite 

sample.

Splitting Procedures

Because volume-paced samples were collected at the 

Buffalo County streamgaging stations, a composite sample 

was prepared by combining all of the discrete samples into 

a cleaned, polyethylene churn splitter (either 8 or 14 liters, 

depending on the number of discrete samples) and sample 

water for the individual WSLH laboratory-analysis bottles 

was drawn off accordingly. Sometimes, however, the 

preset accumulated volume between discrete samples was 

changed during a runoff event to increase or decrease the 

frequency at which samples were collected. In these cases, 

it was necessary to calculate how water from each discrete 

sample needed to be included in the composite sample.

For example, if 10 samples were collected at a certain 

accumulated volume, x, and an additional 10 samples were 

collected at double the accumulated volume, 2x (samples 

were collected one-half as frequently on a volume basis), 

then the first 10 samples represented 10*x/(10*x + 10*2x), 

or one-third of the total event volume. The last 10 samples 

represented 10*2x/(10*x + 10*2x), or two-thirds of the 

total event volume. It follows that by simply combining 

all of the samples equally (each set of 10 bottles would 

represent one-half (10/20) of the total sample volume), 

the first 10 samples would be overrepresented and the last 

10 samples would be underrepresented, thus biasing the 

event-mean sample concentrations.

To correct for this, the 10 bottles collected at the original accumulated volume were combined in a churn splitter 

and one-half of the total volume of these samples was 

drawn off. This water was then returned to a cleaned churn 

splitter and combined with the full volume of the other 10 

samples. Now, the first 10 bottles of the runoff event only 

represented one-third of the total sample volume (1/2*10)/

((1/2*10)+10), and the last 10 bottles represented the other 

two-thirds (10/15). Constituent concentrations for samples 

combined in this manner now correctly represented the 

event-mean concentrations.

Once the composite sample was combined into the 

churn splitter, it was agitated with a churn paddle at a rate 

greater than 9 vertical inches per second and dispensed 

into WSLH sample bottles (fig. 26). Whole-water samples 

and filtered samples were then collected and preserved.

Filtering

A Geotech Environmental Equipment, Inc. capsuletype Dispos-a-filter with a 0.45-micrometer pore size was 

used to filter whole water from event samples for dissolved 

constituents. To initially flush the filter, 500 milliliters of 

deionized water was pumped through the filter, followed 

by 250 milliliters of whole water composite sample. Additional composite sample was then pumped through the 

filter and directed into the appropriate laboratory-analysis 

bottles.

Base-flow samples, which usually had much lower 

sediment concentrations, were filtered with a 47-millimeter-diameter, Geotech Environmental Equipment, Inc. cellulose acetate Geofilter with a 0.45-micrometer pore size. 
Data Analysis for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 37

A variable-speed peristaltic pump was used to initially 

pump 250 milliliters of deionized water through the filter, 

followed by the composite sample.

Laboratory Quality Assurance and Quality 

Control

Both laboratories used for the Discovery Farms and 

Pioneer Farm Projects (WEAL and WSLH) were USGS 

accredited laboratories approved by the USGS Branch 

of Water Quality Systems. The analytical methods of 

each laboratory were therefore approved and published, 

standard operating procedures for these methods were 

documented, an internal laboratory quality-assurance plan 

was approved, a quality-control plan that provided data 

necessary to continuously track precision and accuracy of 

analytical data was in place, and the ability to provide the 

analytical services required was demonstrated. Each laboratory had a series of procedures including continuing calibration verification blanks and standards, matrix spikes, 

duplicates, and reference samples to ensure that constituent 

analyses were accurate and unbiased. Each laboratory was 

also reviewed periodically to ensure that documented procedures continued to be followed and that the conditions 

and practices in the laboratories helped them to produce 

analytical results of a known and documented quality.

Data Analysis for Edge-of-Field, 

Streamgaging, Subsurface-Tile, and 

Meteorological Stations

Data analysis was a process of checking, correcting, 

and finalizing water-quantity, water-quality, and precipitation data to ensure that it was complete and stored accurately within USGS NWIS databases. These processes 

were generally similar to standard USGS protocols for 

completing the end-of-year records for surface-water stations (Garn, 2002); however, there were some aspects of 

the data-analysis process that were developed specifically 

for the Discovery Farms and Pioneer Farm programs.

Edge-of-Field Stations

Water-Quantity Data Analyses

The first step of data analysis for edge-of-field stations was to correct the stage record. All stage corrections 

were applied using the Automated Data Processing System 

(ADAPS), an interface that allowed corrections to be 

applied to data within the NWIS database (U.S. Geological Survey, 2006b). Most traditional USGS surface-water 

streamgaging stations use multiple discharge measurements and corresponding stage readings to adjust the 

stage-discharge relation throughout the year. Discharge 

measurements were not made at edge-of-field stations; 

discharge was computed using precalibrated H flumes in 

which the stage-discharge relation was already predetermined. Comparisons of concurrent staff-gage readings 

and datalogger-stage readings were made throughout the 

water year to ensure that the stage record—and thus the 

discharge record—was accurate.

Miscellaneous-note sheets and sample-retrieval sheets 

(Appendixes 1 and 2) were organized for each station, 

and the concurrent staff-gage and datalogger-stage readings were compiled. Staff-gage readings were sometimes 

different from datalogger-stage readings for a variety of 

reasons including freezing of the bubble tubing, evaporation of water around the float (for some stations with shaft 

encoders), side-to-side flume tilt, and sensor drift. When 

differences between the staff-gage stage and datalogger 

stage exceeded 0.01 foot, a correction was applied to the 

datalogger-stage records in the NWIS database for appropriate periods.

Occasionally, there were periods when computed 

discharges did not reflect the actual discharge conditions 

at the station because of backwater conditions and/or ice 

Sample

bottles

Churn

splitters

Figure 26. Churn splitters and Wisconsin State Laboratory 

of Hygiene (WSLH) sample bottles used for preparing samples 

from the Buffalo County Discovery Farm.
38 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

formation in the flume. Whereas some of these periods 

could be estimated by applying corrections, some of them 

required manual data editing to produce an estimated, continuous record of discharge. These data edits were based 

on station-visit notes, comparisons with nearby gages, 

and temperature records. Figure 27 shows an example of 

discharge data that were edited for an event in which ice 

formed in the flume, causing backup of water and erroneously high computed discharges. Data edits were made in 

HYDRA (a graphical-analysis tool that is a subset program 

in ADAPS), which allowed NWIS data to be displayed 

and modified (U.S. Geological Survey, 2005). Data edits 

were usually applied shortly after a runoff event so that 

the conditions of the event were fresh in the mind of the 

hydrographer.

Peak stages recorded by the crest-stage gage (CSG) 

were also compared to peak stages in the datalogger 

record. When differences between “good” or “excellent” 

CSG peak stages and the peak datalogger stages exceeded 

0.20 foot, a correction was applied. A larger tolerance 

for these differences was allowed because cork readings 

from the CSG were not always accurate, and stage values 

during runoff events were recorded every 1 or 5 minutes 

in the datalogger. Actual stage peaks could have occurred 

that were not recorded by the datalogger during these time 

intervals.

An offset for the datalogger stage was usually applied 

to the stage recorded in the datalogger at most edge-offield stations to account for the thickness of the bubble 

tubing or flume tilt. This offset (generally about 0.015 

foot) allowed the recorded stages to match the staff-gage 

stages during periods of flow but resulted in nonzero 

stages during periods of no flow. For these periods, stages 

were corrected to zero; otherwise, erroneous runoff volumes would have been calculated.

Field personnel made specific notes for any maintenance that may have affected the stage record. If modifications to the stage occurred during a station visit (such as 

during debris or ice removal or an offset change), notes 

were made of the occurrence, date, and time. Corrections 

for these modifications were applied to the stage records 

for appropriate periods.

In addition to compiling notes to determine the appropriate corrections necessary for stage data, the notes also 

were checked to determine whether rating-shift corrections 

were necessary. During field testing, it was determined 

0

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DISCHARGE, IN CUBIC FEET PER SECOND

Corrected discharge

Original discharge

Data edited in HYDRA using field notes, 

air temperature, and comparison 

with nearby gages 

Figure 27. Example of corrections made to discharge data using HYDRA during periods that ice formed in the flume during a 

runoff event. HYDRA is a graphical-analysis tool that is a subset program in the Automated Data Processing System (ADAPS), 

which allows U.S. Geological Survey data from the National Water Information System (NWIS) to be displayed and modified.
Data Analysis for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 39

that, when the H flumes were level, measured discharge 

matched the rated discharge very closely. However, it was 

determined that a flume floor tilt from entrance to exit of 

just 0.02 foot in a 2.5-foot H flume would cause the stage 

to be underestimated by that same 0.02 foot. With this 

0.02-foot floor tilt and a measured stage of 0.3 feet, the 

resultant discharge would be underestimated by more than 

10 percent compared to a level flume.

Although the stage-discharge relation for an H flume 

was stable, accuracy was highly dependent on the flumes 

being level from front to back and from side to side. Accurate surveys of flume tilt were done at least twice per year 

to determine the appropriate shift corrections. When surveys revealed that flume tilt exceeded 0.01 foot, a ratingshift correction was applied to the record for appropriate 

periods.

Once all corrections were applied, the stage and 

discharge record was recomputed and reviewed to ensure 

that the data and shift corrections were applied appropriately. Once reviewed, the stage and discharge records were 

“approved” in NWIS, a process that locks the data to prevent further modification. A station-analysis document was 

created to describe the flow conditions at the station during 

the year and to provide detail for extreme runoff events, all 

data and shift corrections, and any other corrections that 

were deemed necessary.

The next step in the data-analysis process was to 

determine runoff-event start and end times and volumes. 

Although start and end times were determined during 

the spitting-record process, they were usually based on 

raw data. This determination was based on finalized data. 

HYDRA was used to visually evaluate the stage record and 

to determine runoff-event start and end times. For edgeof-field stations, runoff events were assumed to begin just 

before the time when the stage increased above zero and 

were assumed to end at the time when the stage returned to 

zero. Sometimes it was necessary to add data points to the 

record to estimate the beginning or end of an event because 

the 1- or 5-minute data output during runoff events did not 

begin until the stage increased above the data threshold 

(approximately 0.04 foot).

After determining runoff-event start and end times, 

the total runoff-event volume and event-peak discharge 

were calculated. As noted earlier, runoff-event times for 

edge-of-field stations began and ended at a stage of zero, 

whereas the sampled portions of the runoff events (using 

raw data) generally began and ended at a stage of approximately 0.05 foot. For this reason, the calculated sampled 

volumes were usually slightly less than total event volumes.

A data-summary spreadsheet was prepared for each 

edge-of-field station (Appendix 4). These spreadsheets 

included information for start and end time of runoff 

events, percentage of event volume sampled, number 

of discrete samples collected per event, peak discharge, 

precipitation depth and intensity, runoff-event volume, 

and ground conditions preceding an event (frozen soil or 

unfrozen soil), as well as constituent concentrations, loads, 

and yields. They also included constituent concentrations 

for QC samples taken throughout the water year. The datasummary spreadsheets were the primary form of shared 

data for edge-of-field stations for the Discovery Farms and 

Pioneer Farm programs.

Water-Quality Data Analyses

The next step of data analysis for edge-of-field stations was to organize all the water-quality constituent concentrations from the WEAL and enter them into the USGS 

QWDATA database (U.S. Geological Survey, 2006b). 

Results were received from the WEAL via email throughout the year as they were released. When the results were 

received, they were matched to the appropriate sampled 

runoff events based on station name, event identification 

number, and sample start and end time. The constituent 

concentrations and any associated laboratory codes were 

then copied and pasted into the data-summary spreadsheet 

for each station. After the spreadsheet had been checked 

and finalized at the end of the water year, the water-quality 

data were imported into the QWDATA database.

Estimating Constituent Concentrations for 

Unsampled Runoff Events

Few runoff events were not sampled at the edge-offield stations. Annual sample-volume coverage for the 

edge-of-field stations was typically 90 percent or greater. 

In order to determine annual constituent loads, event-mean 

concentrations were estimated for runoff events that were 

not sampled by substituting concentrations from similar runoff events that were sampled during similar time 

periods. First, all sampled runoff events were evaluated 

to determine whether they represented a “typical” runoff 

event for a particular time period. Anomalous events were 

considered to be events influenced by on-farm activities 

that were not representative of the yearly farm activities, 

such as construction activities. Anomalous events that 

were sampled were included in the calculations for annual 

load, but they were not used to estimate concentrations 

for unsampled runoff events. Runoff events that had poor 
40 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

sample coverage (generally less than four discrete samples 

per runoff event) also were not used to estimate concentrations for unsampled runoff events.

Runoff events were compared with regard to date of 

runoff, total volume, peak discharge, and characteristics of 

precipitation that induced the surface-water runoff event 

(precipitation depth and intensity). Event-mean concentrations from the sampled runoff event that most represented 

the qualities of the unsampled event were then used as 

estimates for the unsampled event. The annual load was 

determined by summing loads for sampled and unsampled 

runoff events.

Streamgaging Stations

Water-Quantity Data Analyses

Data analysis for streamgaging stations was similar 

to data analysis at edge-of-field stations; the first step of 

which was to correct the stage record supplied by the dataloggers. All Discovery Farms streamgaging stations were 

monitored with H flumes in which the stage readings were 

converted to discharge by use of a predetermined rating. 

Data corrections and any other necessary data modifications were applied in the same manner as with edge-offield stations.

Flumes were not used at streamgaging stations for 

at Pioneer Farm. Rather, discharge was computed from a 

stage-discharge relation that was determined from multiple 

measurements of discharge (Garn, 2002). As with edge-offield stations, data corrections were made for differences 

between actual stream stage (measured from a known 

datum) and datalogger stage; however, additional steps 

were required to ensure that discharge data were accurate.

Discharge measurements were made every 3 weeks 

and during periods of high discharge. A base rating that 

best represented the relation between stage and discharge 

was constructed with these measurements. Throughout the 

year, discharge measurements were compared to the rating 

to determine whether corrections were necessary to adjust 

the base rating so that it was representative of the actual 

discharge conditions. Corrections were often necessary 

for ice cover in winter and vegetative growth in the stream 

channel during summer. Runoff events that scoured or 

deposited sediment in the stream channel often necessitated corrections or rating modification.

Unlike edge-of-field stations, events at streamgaging 

stations were assumed to begin when the stage or discharge hydrograph increased above base flow and ended 

when there was no overland flow component and a minimal bank storage component. Start- and end-time determinations were made before splitting records were prepared, 

so the event-sample volume was usually the same as the 

total-event volume for streamgaging stations.

Once the discharge record was completed, checked, 

and approved, an analysis for significant, unsampled runoff 

events greater than 0.1 percent of the total annual volume 

(including base flow) was done. The discharge hydrograph 

for each unsampled-runoff event was plotted on paper 

and start and end times were determined by use of the 

graphical method described earlier; runoff-event volumes 

then were calculated. These significant, unsampled runoff 

events were used in the analysis of water-quality data for 

streamgaging stations.

Data-summary spreadsheets were compiled for 

streamgaging stations in a similar fashion to edge-offield stations, with the start and end time of runoff events, 

percentage of event volume sampled, number of discrete 

samples per event, peak discharge, precpitation depth 

and intensity, constituent concentrations, and so forth. 

Data-summary spreadsheets for streamgaging stations 

were different from edge-of-field stations in that they did 

not include discharge data for the entire water year. Only 

sampled runoff events and those unsampled events deemed 

significant were included. Data-summary spreadsheets for 

streamgaging stations also contained constituent concentrations for monthly base-flow samples.

For these reasons, data-summary spreadsheets were 

not considered to be the primary form of shared data 

for streamgaging stations for the Discovery Farms and 

Pioneer Farm programs. Rather, additional data processes 

were necessary to create a supplementary document that 

described the entire water year for event- and base-flow 

components.

Water-Quality Data Analyses

Water-quality data for streamgaging stations were 

received from the WEAL and entered into QWDATA by 

the same process as for edge-of-field stations. The Buffalo 

County stations were an exception because analyses were 

done at the WSLH. For these stations, concentration data 

were transmitted from the WSLH database to the WWSC, 

and results were subsequently uploaded to the QWDATA 

database throughout the year.
Data Analysis for Edge-of-Field, Streamgaging, Subsurface-Tile, and Meteorological Stations 41

Estimating Constituent Concentrations for 

Significant Unsampled Runoff Events

In order to accurately determine annual constituent 

loads for streamgaging stations, it was sometimes necessary to estimate constituent concentrations for significant, unsampled runoff events. Significant runoff events 

were considered to be those representing greater than 0.1 

percent of the annual discharge. Small (yet significant) 

unsampled events were those between 0.1 and 2 percent 

of the annual discharge, whereas large, unsampled events 

were those 2 percent or more of the annual discharge. Runoff events representing less than 0.1 percent of the annual 

discharge were considered insignificant.

Estimated concentrations for small and large unsampled runoff events were determined differently. Constituent 

concentrations for small, unsampled events were estimated 

in a manner similar to that described for edge-of-field stations. Runoff events were compared with regard to date of 

runoff, total volume, peak discharge, and the precipitation 

characteristics that caused the runoff event (precipitation 

amount and intensity). Event-mean concentrations from 

the sampled runoff event that most represented the qualities of the unsampled event were then used as estimates.

Constituent concentrations for large, unsampled 

events were estimated by use of regressions of multiple 

variables including runoff volume, precipitation amount 

and intensity, peak discharge, and season. Multiple years 

of data were usually necessary to obtain a wide range of 

runoff events for satisfactory regression tests. Only data for 

sampled-runoff events were used in the regressions.

Daily and Annual Load Computation

The next step of the data-analysis process for streamgaging stations was to determine the daily and annual constituent loads. Event-mean concentrations for sampled and 

unsampled events were organized by start and end time in 

a spreadsheet. Monthly base-flow constituent concentrations were used within the spreadsheet to represent stream 

conditions from the time immediately after an event ended 

to the time at which the next event began. The spreadsheet 

data were then imported into the Graphical Constituent 

Loading Analysis System (GCLAS) (Koltun and others, 

2006), which was used to compute a daily load for each 

constituent. Annual loads were computed by summing all 

of the daily loads.

To better understand the interactions between agricultural practices and stream-water quality, it was often useful 

to separate streamflow into base-flow and event-flow components. On-farm practices that contributed to runoff could 

then be correlated to the event-flow loads, whereas baseflow loads could be used to determine the contribution by 

ground water and/or on-farm practices that contributed to 

ground water. The USGS Hydrograph Separation Program 

(HYSEP) (Sloto and Crouse, 1996) was used to separate 

daily discharges and constituent loads into base-flow and 

event-flow components.

Data spreadsheets with daily constituent load, daily 

discharge, and daily base-flow and event-flow components were compiled for each streamgaging station. These 

spreadsheets, in addition to the data-summary spreadsheets, were the primary forms of shared data for streamgaging stations for the Discovery Farms and Pioneer Farm 

programs.

Subsurface-Tile Stations

Water-Quantity Data Analyses

Data analysis for subsurface-tile stations was similar 

to data analysis at edge-of-field and streamgaging stations, 

the first step of which was to correct the stage record. All 

Discovery Farms subsurface-tile stations were monitored 

with trapezoidal flumes in which the stage readings were 

converted to discharge by use of a predetermined rating. 

Data corrections and any other necessary data modifications were applied in the same manner as with edge-offield stations.

There were occasional and brief periods where the 

capacity of the flume at the in-field subsurface-tile stations 

was exceeded (surcharging), resulting in stage data that did 

not accurately represent discharge. These surcharge periods were typified by an abrupt increase in stage, followed 

by a steep recession, and then by an abrupt transition to a 

period of gradual recession (fig. 28). The discharge at the 

transition stages was assumed to be the maximum tilecapacity discharge. This assumption was verified by periodic measurements of velocity (and thus discharge) during 

surcharge periods. Discharge during periods of surcharge 

was edited in NWIS using HYDRA.

In addition to extended periods of surcharge, variable 

backwater conditions were observed at the subsurface-tile 

station in Manitowoc County. Backwater differed from 

surcharge in that the discharge for a given stage was variable depending on downstream conditions. Velocity meters 

were installed to determine a velocity-stage-discharge relation to obtain a more accurate record of discharge.

Data-summary spreadsheets were compiled for 

subsurface-tile stations in a similar fashion to those for 
42 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

edge-of-field stations, with the start and end time of runoff 

events, percentage of event volume sampled, number of 

discrete samples per event, peak discharge, precipitation 

depth and intensity, constituent concentrations, and so 

forth. The data-summary spreadsheets were considered to 

be the primary form of shared data for subsurface-tile stations for the Discovery Farms program.

Water-Quality Data Analyses

Water-quality data for subsurface-tile stations were 

received from the WEAL and entered into QWDATA by 

the same process as for edge-of-field and streamgaging 

stations.

Estimating Constituent Concentrations for 

Significant Unsampled Runoff Events

After the spreadsheet was checked and finalized at 

the end of the water year, constituent concentrations were 

loaded from the spreadsheet into the QWDATA database. 

Event-mean concentrations from sampled-runoff events 

that most represented the qualities of unsampled events 

were used as estimates for unsampled events. Annual 

sample-volume coverage for subsurface-tile stations 

was typically 90 percent or greater. The annual load was 

determined by summing loads for sampled and unsampled 

runoff events.

Meteorological Data

Data analysis for meteorological stations primarily 

involved correcting and checking the precipitation record. 

The tipping-bucket precipitation gages were not heated, so 

data interpreted to be frozen precipitation melting in the 

precipitation-gage funnel were removed from the record. 

HYDRA was used to determine these periods by plotting 

precipitation data with air temperature, relative humidity, 

solar radiation, and discharge data. Spurious data created 

by field personnel during station visits also were removed 

from the record at this time.

Additional corrections made to the precipitation data 

were based on calibrations that were done at least once per 

year. A calibration was done by putting a known amount 

of water into the precipitation-gage funnel at an equivalent 

rate of approximately 2 inches per hour. If the amount of 

water measured by the precipitation gage was greater than 

5 percent different from the expected value, a correction 

was applied in ADAPS for this difference. The correction 

was usually prorated from the previous calibration, unless 

0

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DISCHARGE, IN CUBIC FEET PER SECOND

Corrected discharge

Original discharge

Figure 28. Example of corrections made to discharge data due to surcharge conditions in a subsurface tile.
Summary and Conclusions 43

observations indicated that the correction should have been 

applied at a different date.

Occasionally, a precipitation gage did not operate 

properly due to clogging or other operational issues. Data 

from a precipitation gage at a water-quality station located 

within several miles (although usually much closer, less 

than half a mile) of the precipitation gage in question were 

substituted for the period of missing or inaccurate record. 

The substitution of precipitation-gage data from one 

station to another was documented and only done when 

runoff characteristics between the gages were similar, indicating similar precipitation. Incidents where precipitation 

data were substituted between precipitation gages were 

marked as estimated.

Once corrected and checked, the daily sum precipitation data were approved in NWIS. A station-analysis 

document was then created to describe the conditions at 

the station during the year and to detail extreme events, 

all data corrections, and any other corrections that were 

deemed necessary.

In addition to the NWIS-published daily precipitation 

amounts, computations were made for individual precipitation events. Precipitation amount, maximum 5-, 10-, 15-, 

30-, and 60-minute precipitation intensity, and the Universal Soil Loss Equation erosivity index also were computed 

for all individual precipitation events throughout the water 

year. The precipitation amount and erosivity index values 

were used to populate the data-summary spreadsheets for 

water-quality stations. All other meteorological data were 

stored in NWIS, but not published.

Summary and Conclusions

The University of Wisconsin–Madison Discovery 

Farms and University of Wisconsin–Platteville Pioneer 

Farm programs were created in 2000 to help Wisconsin 

farmers meet environmental and economic challenges. As 

a partner with each program, and in cooperation with the 

Wisconsin Department of Natural Resources and the Sand 

County Foundation, the U.S. Geological Survey (USGS) 

Wisconsin Water Science Center (WWSC) installed, maintained, and operated equipment to collect water-quantity 

and water-quality data from 25 edge-of-field, 6 streamgaging, and 5 subsurface-tile stations at 7 Discovery Farms 

and Pioneer Farm. The farms are located in the southern 

half of Wisconsin and represent a variety of landscape settings and crop- and animal-production enterprises common 

to Wisconsin agriculture. Meteorological stations were 

established at most farms to measure precipitation, wind 

speed and direction, air and soil temperature (in profile), 

relative humidity, solar radiation, and soil moisture (in 

profile). Data collection began in September 2001 and is 

continuing through the present (2008).

This report describes methods used by USGS WWSC 

personnel to collect, process, and analyze water-quantity, 

water-quality, and meteorological data for edge-of-field, 

streamgaging, subsurface-tile, and meteorological stations at Discovery Farms and Pioneer Farm from September 2001 through October 2007. Information presented 

includes equipment used; event-monitoring and samplecollection procedures; station maintenance; sample handling and processing procedures; water-quantity, waterquality, and precipitation data analyses; and procedures 

for determining estimated constituent concentrations for 

unsampled runoff events.

Edge-of-field, streamgaging, and subsurface-tile 

stations typically used similar equipment to monitor and 

collect water-quantity and water-quality data throughout 

the year. Aluminum, clam-style equipment enclosures 

were placed at each monitoring location to contain equipment. Nonsubmersible pressure transducers coupled with 

a nitrogen bubbling system were used to monitor stages 

in H flumes, trapezoidal flumes, or open stream channels. 

Discharges were computed from the stage-discharge relations determined for each flume or from periodic measurements of open-channel flow. Flume levels were routinely 

recorded to ensure rating accuracy.

Automated, refrigerated, 24-bottle ISCO 3700R samplers were used to collect discrete, time-paced and volumepaced water samples during runoff events. A specialized 

datalogger program executed by Campbell Scientific, Inc.

CR10 and CR10X dataloggers was used to read, store, and 

control sensors and devices at each station. A combination 

of land telephone lines, Campbell Scientific, Inc.RF400 

spread-spectrum radio/modems, and Air-Link Communications, Inc. Raven cellular modems was used to allow 

two-way datalogger communication. Two-way telemetry, 

coupled with Campbell Scientific, Inc. PC208W and Real 

Time Data Monitor (RTDM) retrieval and data-display 

software, greatly enhanced ability to determine runoff conditions, change sample frequency, and determine equipment functionality. Virtual Private Network (VPN) and 

Remote Desktop Connection (RDC) software were used to 

gain authenticated and secure access to real-time datalogger data from any properly configured computer having 

Internet access or a connected phone modem.

Discrete water samples collected by the ISCO automated samplers were generally retrieved within 24 hours 

of the end of a runoff event. Prior to sample analyses, a 
44 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

“splitting record” was developed for each runoff event that 

contained time-series data for stage, discharge, precipitation, and selected sample information. On the basis of the 

splitting record, appropriate aliquots from each discrete 

sample were combined to create a single, composite sample. This sample was then analyzed for sediment, nutrients, 

and other selected constituents—the concentrations of 

which represented the average or event-mean concentration of the runoff event. Constituent concentrations from 

this composite sample were multiplied by the runoff-event 

volume to compute runoff-event loads and yields.

Field blanks and cross-section coefficient samples 

were collected to determine whether contamination was 

introduced by the entire sampling process or whether constituent concentrations in the automatic, discrete samples 

(which were pumped from a single point at the tip of the 

sample-intake line) were representative of the constituent 

concentrations in the cross section of the water column.

Data analysis was done in a similar fashion for each 

monitoring station. In all cases, the gage-height record 

was corrected for a variety of reasons including sensor drift, freezing, and algal growth. The discharge was 

computed from the stage-discharge relation determined 

for each flume size and type. A station-analysis document 

was created to describe the discharge conditions at the 

station during the year and to provide detail for extreme 

runoff events, all data and shift corrections, and any other 

corrections that were deemed necessary. Data analysis for 

meteorological stations primarily involved correcting and 

checking the precipitation record. Precipitation gages were 

calibrated at least once per year.

Water-quality data were received from the laboratory and entered into the USGS QWDATA database, and 

spreadsheets were populated for each monitored station. 

These spreadsheets contained the start and end time of runoff events, percentage of event volume sampled, number 

of discrete samples per event, peak discharge, precipitation 

depth and intensity, constituent concentrations, and event 

and annual loads and yields. To compute annual loads 

for each station, sampled and unsampled runoff events 

needed to be summed. For all station types, unsampled 

runoff events typically represented less than 10 percent 

of the annual load. Event-mean concentrations for small 

unsampled events were estimated by substituting concentrations from similar, sampled runoff events that occurred 

during similar time periods. Constituent concentrations for 

large, unsampled runoff events were estimated by use of 

regressions of multiple variables including runoff volume, 

precipitation amount and intensity, peak discharge, and 

season. Data from multiple years were usually necessary 

to obtain a range of runoff events to perform satisfactory 

regression analyses. Only data for sampled runoff events 

were used in the regressions.

Additional steps were taken to complete the data 

analysis for streamgaging stations. Discharge and constituent-load data were separated into base-flow and event-flow 

components for these stations. On-farm practices that contributed to overland flow could be used to correlate to the 

runoff-event loads, whereas base-flow loads could be used 

to determine the contribution from ground water and/or 

on-farm practices that contributed to ground water. Spreadsheets with daily constituent load and discharge (and the 

base-flow and event-flow components) were compiled for 

each streamgaging station.

Acknowledgments

The authors would like to thank the following participants for building the programs for which the methods 

were applied: Dennis Frame (Discovery Farms Co-Director), Frederick Madison (Discovery Farms Co-Director), 

and Thomas Hunt (formerly the Director of Research and 

Outreach at Pioneer Farm).

References

Buchanan, T.J., and Somers, W.P., 1969, Discharge measurements at gaging stations: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 3, 

chap. A8, 65 p.

Garn, H.S., 2002, Surface-water quality-assurance plan for 

the Wisconsin District of the U.S. Geological Survey, 

Water Resources Division: U.S. Geological Survey 

Open-File Report 02–30, 52 p.

Groetsch, K.J., and Coleman, J., 2001, Tribal monitoring 

of stream flow in Swamp Creek, Forest County, Wisconsin: QAPP prepared by the Great Lakes Indian Fish and 

Wildlife Commission under grant X–995574–01.

Koltun, G.F.; Eberle, Michael; Gray, J.R.; and Glysson, 

G.D., 2006, User’s manual for the Graphical Constituent 

Loading Analysis System (GCLAS): U.S. Geological 

Survey Techniques and Methods 4–C1, 51 p.

Linsley, R.K., Jr., Kohler, M.A., and Paulhus, J.L.H., 1982, 

Hydrology for engineers (3d ed.): New York, McGrawHill, 508 p.
References 45

Mathey, S.B., ed., 1998, National Water Information 

System (NWIS): U.S. Geological Survey Fact Sheet 

FS–027–98, 2 p.

Moran, J.M., and Hopkins, E.J., 2002, Wisconsin’s 

weather and climate: Madison, Wis., University of Wisconsin Press, 321 p.

Porterfield, George, 1972, Computation of fluvial-sediment discharge: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 3, chap. C3, 66 p.

Rantz, S.E., and others, 1982, Measurement and computation of streamflow; Volume 1, Measurement of stage 

and discharge: U.S. Geological Survey Water-Supply 

Paper 2175, 313 p.

Richards, K.D., Elder, J.F., and Corsi, S.R., 2006, Qualityassurance plan for water-quality activities in the Wisconsin Water Science Center: Unpublished document 

on file at the U.S. Geological Survey Wisconsin Water 

Science Center, Middleton, Wis.

Sloto, R.A., and Crouse, M.Y., 1996, HYSEP—A computer program for streamflow hydrograph separation 

and analysis: U.S. Geological Survey Water-Resources 

Investigations Report 96–4040, 46 p.

U.S. Geological Survey, Wisconsin District, Data 

Archiving and Management Process Action Team, 2000, 

Policy recommendations for issues regarding the archival and management of hydrologic information, and 

plan and guidance for the management and archiving of 

hydrologic data in the Wisconsin District: Unpublished 

document on file at the U.S. Geological Survey Wisconsin Water Science Center, Middleton, Wis., 28 p.

U.S. Geological Survey, 2005, Use of the program 

HYDRA to estimate or modify unit values in ADAPS: 

Office of Surface Water Technical Memorandum 

2005.07, accessed August 7, 2007 at http://water.usgs.

gov/admin/memo/SW/sw05.07.html

U.S. Geological Survey, 2002, NWISWeb—New site for 

the Nation’s water data: U.S. Geological Survey Fact 

Sheet 128–02, 2 p.

U.S. Geological Survey, 2006a, User’s manual for the 

National Water Information System of the U.S. Geological Survey: Water-quality system: U.S. Geological 

Survey Open-File Report, version 4.6, 400 p.

U.S. Geological Survey, 2006b, User’s manual for the 

National Water Information System of the U.S. Geological Survey: Automated Data Processing System 

(ADAPS): U.S. Geological Survey Open-File Report, 

version 4.6, 427 p.

Wisconsin Legislative Fiscal Bureau, 2001, Agricultural 

Stewardship Initiative (UW System): Wisconsin Joint 

Committee on Finance Paper #955, LFB 2001–03, Budget Summary: Page 687, #15, accessed March 14, 2007, 

at http://www.legis.state.wi.us/lfb/2001-03budget/2001-

03budgetpapers/955.pdf
46 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Appendixes
Appendixes 47

Appendix 1. Example of a sample-retrieval sheet.
48 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Appendix 2. Example of a miscellaneous-note sheet.
Appendixes 49

Appendix 3. Example of a splitting record.
50 Methods of Data Collection, Sample Processing, and Data Analysis at Discovery Farms and Pioneer Farm, Wis., 2001–7

Appendix 4. Example portion of a data-summary spreadsheet.

Discovery Farms Waterway Site No 1 Near Belmont, WI HT = Holding Time

USGS Station ID: 423912090170800 P = Preservation Error

Area (acres): 16.9 Discrete Sample

Multiplication Factor for Load, in pounds (from cubic feet): 0.00006242824 Storm not sampled - concentration is estimated

Date Range: 12/3/03 - 9/30/04 SS sample - do not double count!

Results not reported by lab - concentration is estimated

Sample Runoff Volume (99906), cubic feet

Percent of Storm Runoff Sampled, percentInstantaneous Discharge, cfsNumber of SubsamplesStorm Number, sequential, from Oct-Sep

Storm Type (rain, snowmelt, or rain/snowmelt)

Storm Precipitation, inches

Storm Erosivity IndexPeak Discharge, cfs

Storm Runoff Volume, cubic feet

Storm Runoff, inches

Start Stop UWSP Lab # Field ID Start Stop

02/18/04 21:06 02/19/04 10:34 34-04-10 R1-1A COMP 1219 99% - 16 02/18/2004 21:00 02/19/2004 11:00 1 snowmelt - - 0.03 1236 0.020

02/20/04 05:09 02/20/04 07:04 34-04-11 R1-1B COMP 2394 100% - 4 02/20/2004 05:00 02/20/2004 07:04 0.44 2403 0.039

02/20/04 07:05 02/20/04 12:34 34-04-12 R1-1C COMP 10773 100% - 11 02/20/2004 07:04 02/20/2004 12:34 0.69 10821 0.176

02/20/04 12:35 02/20/04 14:34 34-04-13 R1-1D COMP 5423 99% - 4 02/20/2004 12:34 02/20/2004 14:34 1.12 5450 0.089

02/20/04 14:35 02/20/04 23:34 34-04-14 R1-1E COMP 3855 99% - 11 02/20/2004 14:34 02/20/2004 23:34 0.53 3885 0.063

02/20/04 23:35 02/21/04 08:44 34-04-15 RI-IF COMP 968 72% - 9 02/20/2004 23:34 02/21/2004 14:02 0.05 1350 0.022

02/21/04 14:03 02/22/04 03:45 34-04-16 RI-1G COMP 3558 93% - 2 02/21/2004 14:02 02/22/2004 12:00 - - 0.23 3836 0.063

02/22/04 16:15 02/23/04 11:59 34-04-25 R1-1H COMP 5844 100% - 7 02/22/2004 15:48 02/23/2004 11:59 0.12 0.09 0.23 5865 0.096

02/23/04 12:00 02/24/04 02:34 34-04-26 R1-1I COMP 8051 100% - 6 02/23/2004 11:59 02/24/2004 04:00 - - 0.45 8089 0.132

02/25/04 17:16 34-04-131 R1-1 55 DIS 616 100% 0.048 1 02/25/2004 15:00 02/25/2004 22:00 4 snowmelt - - 0.07 616 0.010

02/26/04 15:17 34-04-132 R1-1 58 DIS 965 100% 0.096 1 02/26/2004 14:00 02/26/2004 19:00 5 snowmelt - - 0.10 965 0.016

0% - 0 02/27/2004 14:00 02/27/2004 19:00 6 snowmelt - - 0.06 555 0.009

0% - 0 02/28/2004 13:00 02/28/2004 16:00 7 snowmelt - - 0.06 356 0.006

03/04/04 19:57 03/04/04 23:03 47-04-43 R1-2A COMP 15840 99% - 9 03/04/2004 19:53 03/04/2004 23:04 3.62 16041 0.261

03/04/04 23:05 03/05/04 05:00 47-04-44 R1-2B COMP 15362 99% - 15 03/04/2004 23:04 03/05/2004 05:09 3.37 15573 0.254

03/04/04 19:57 03/05/04 05:00 47-04-45 R1-2SS COMP 31605 100% - 24 03/04/2004 19:53 03/05/2004 05:09 3.62 31614 0.515

0% - 0 05/21/2004 22:47 05/21/2004 23:01 9 rain 2.06 41.3 0.08 42 0.001

05/23/04 00:17 05/23/04 01:34 180-04-1 R1-3 32395 100% - 13 05/23/2004 00:16 05/23/2004 02:00 10 rain 1.24 29.0 39.90 32519 0.530

05/23/04 03:43 05/23/04 05:24 180-04-7 R1-4 12022 99% - 10 05/23/2004 03:42 05/23/2004 06:00 11 rain 0.71 7.52 7.76 12194 0.199

0% - 0 05/30/2004 07:53 05/30/2004 09:02 12 rain 1.03 11.9 1.50 2299 0.037

06/12/04 00:54 06/12/04 01:37 205-04-4 R1-5 1008 97% - 6 06/12/2004 00:52 06/12/2004 01:40 13 rain 0.67 6.78 0.90 1042 0.017

06/16/04 20:02 06/16/04 21:02 221-04-1 R1-6 7083 99% - 7 06/16/2004 20:01 06/16/2004 21:06 14 rain 1.44 34.1 7.08 7122 0.116

Yearly Totals 127375 96% 132 14 132259 2.16

Frozen 45426 0.74

Non-Frozen 86833 1.42

8 rain

0.37 0.66

1.21 3.62

3 rain/snowmelt

2 rain/snowmelt

Sample Information Storm Information

Sample Times Lab Information Storm Times
Appendixes 51

Total Solids (00500), mg/L

Flag_Total Solids

Total Solids Load, pounds

Total Solids Yield, pounds per acre

Total Suspended Solids (00530), mg/L

Flag_Total Suspended Solids

Total Suspended Solids Load, pounds

Total Suspended Solids Yield, pounds per acre

Suspended Sediment (80154), mg/L

Flag_Suspended Sediment

Suspended Sediment Load, pounds

Suspended Sediment Yield, pounds per acre

Total Volatile Suspended Solids (00535), mg/L

Flag_Total Volatile Suspended Solids

Total Volatile Suspended Solids Load, pounds

Total Volatile Suspended Solids Yield, pounds per acre

Chloride (00940), mg/LFlag_Chloride

Chloride Load, pounds

Chloride Yield, pounds per acre

NO2+NO3(N) (00631), mg/LFlag_NO2+NO3(N)

NO2+NO3(N) Load, pounds

NO2+NO3(N) Yield, pounds per acre

Ammonium (N) (00608), mg/LFlag_Ammonium (N)Ammonium (N) Load, pounds

1779 137.3 8.1 66 5.1 0.3 44 3.4 0.2 59 4.6 0.3 117 9.0 0.5 0.31 0.024 0.001 43.6 3.36

1383 207.4 12.3 57 8.5 0.5 44 6.6 0.4 49 7.3 0.4 90 13.5 0.8 0.08 0.012 0.001 34.2 5.13

1287 869.4 51.4 44 29.7 1.8 37 25.0 1.5 33 22.3 1.3 82 55.4 3.3 0.08 0.054 0.003 26.5 17.90

1144 389.2 23.0 42 14.3 0.8 31 10.5 0.6 32 10.9 0.6 71 24.2 1.4 0.06 0.020 0.001 20.6 7.01

1122 272.1 16.1 41 9.9 0.6 23 5.6 0.3 35 8.5 0.5 67 16.2 1.0 0.06 0.015 0.001 20.0 4.85

1094 92.2 5.5 28 2.4 0.1 29 2.4 0.1 25 2.1 0.1 67 5.6 0.3 0.06 0.005 0.000 19.0 1.60

1088 260.5 15.4 26 6.2 0.4 19 4.6 0.3 22 5.3 0.3 63 15.1 0.9 0.03 0.007 0.000 24.8 5.94

774 283.4 16.8 30 11.0 0.6 27 9.9 0.6 26 9.5 0.6 48 17.4 1.0 0.05 0.018 0.001 12.8 4.69

454 229.3 13.6 26 13.1 0.8 11 5.6 0.3 20 10.1 0.6 26 12.9 0.8 0.57 0.288 0.017 8.1 4.09

300 HT 11.5 0.7 24 HT 0.9 0.1 2 HT 0.1 0.0 13 HT 0.5 0.0 15 HT 0.6 0.0 1.04 HT 0.040 0.002 5.5 HT 0.21

323 HT 19.5 1.2 31 HT 1.9 0.1 29 HT 1.7 0.1 16 HT 1.0 0.1 15 HT 0.9 0.1 1.17 HT 0.070 0.004 6.0 HT 0.36

300 10.4 0.6 24 0.8 0.0 2 0.1 0.0 13 0.5 0.0 15 0.5 0.0 1.04 0.036 0.002 5.5 0.19

300 6.7 0.4 24 0.5 0.0 2 0.0 0.0 13 0.3 0.0 15 0.3 0.0 1.04 0.023 0.001 5.5 0.12

328 328.5 19.4 66 66.1 3.9 65 65.1 3.9 21 21.0 1.2 9 8.5 0.5 4.95 4.957 0.293 1.6 1.60

281 273.2 16.2 37 36.0 2.1 47 45.7 2.7 10 9.7 0.6 9 8.3 0.5 4.26 4.142 0.245 1.8 1.75

265 523.0 30.9 47 92.8 5.5 46 90.8 5.4 14 27.6 1.6 9 17.8 1.1 4.65 9.177 0.543 1.6 3.16

292 0.8 0.0 204 0.5 0.0 280 0.7 0.0 29 0.1 0.0 1 0.0 0.0 1.41 0.004 0.000 0.4 0.00

2687 5454.9 322.8 2632 5343.2 316.2 2670 5420.3 320.7 302 613.1 36.3 2 3.0 0.2 0.60 1.218 0.072 0.6 1.30

1290 982.1 58.1 1167 888.4 52.6 1190 905.9 53.6 248 188.8 11.2 2 1.1 0.1 0.66 0.502 0.030 0.3 0.24

292 41.9 2.5 204 29.3 1.7 280 40.2 2.4 29 4.2 0.2 1 0.1 0.0 1.41 0.202 0.012 0.4 0.05

292 HT 19.0 1.1 204 HT 13.3 0.8 280 HT 18.2 1.1 29 HT 1.9 0.1 1 0.0 0.0 1.41 0.092 0.005 0.4 0.02

432 192.1 11.4 356 158.3 9.4 366 162.7 9.6 39 17.3 1.0 1 0.4 0.0 1.13 0.502 0.030 0.2 0.09

10081 597 6640 393 6734 398 939 56 193 11.4 12 0.7 61

2789 165 104 6 75 4 83 5 172 10.2 1 0.0 55

7292 431 6535 387 6659 394 856 51 22 1.3 12 0.7 5

Appendix 4. Example portion of a data-summary spreadsheet—Continued.
Prepared by the Wisconsin Water Science Center:

U.S. Geological Survey

Wisconsin Water Science Center

8505 Research Way

Middleton, WI 53562

tel: (608) 828-9901

fax: (608) 821-3817

This publication is available online at URL:

http://pubs.water.usgs.gov/ofr2008-1015

Information regarding the Wisconsin Water Science Center 

is available at URL:

http://wi.water.usgs.gov