Sources of Phosphorus in Stormwater and 

Street Dirt from Two Urban Residential 

Basins In Madison, Wisconsin, 1994–95

By R.J. Waschbusch, W.R. Selbig, and R.T. Bannerman

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 99–4021

Prepared in cooperation with the

CITY OF MADISON

WISCONSIN DEPARTMENT OF NATURAL RESOURCES

Middleton, Wisconsin

1999

Cover photos (clockwise from upper left): street sampler, driveway sampler, lawn sampler, and roof sampler.
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information write to: Copies of this report can be purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Branch of Information Services

8505 Research Way Box 25286

Middleton, WI 53562-3586 Denver, CO 80225-0286

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement

by the U.S. Government.
CONTENTS III

CONTENTS

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

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

Study-area description................................................................................................................................................. 3

Acknowledgments....................................................................................................................................................... 5

Data-collection equipment and methods............................................................................................................................... 5

Stormwater-sample collection and processing protocols............................................................................................ 6

Street-dirt collection and analysis ............................................................................................................................... 8

Sources of phosphorus .......................................................................................................................................................... 8

Measured concentrations in runoff from source areas ................................................................................................ 8

Calibration of the Source Loading and Management Model (SLAMM).................................................................... 10

Water-volume calibration.................................................................................................................................. 14

Sediment calibration ......................................................................................................................................... 15

Phosphorus calibration...................................................................................................................................... 17

Distribution of source-area loads ................................................................................................................................ 17

Sediment and phosphorus mass in street-dirt samples................................................................................................ 18

Summary and conclusions .................................................................................................................................................... 20

Selected references................................................................................................................................................................ 21

Appendixes:

Appendix A–Detailed study data tables...................................................................................................................... 23

Appendix B– SLAMM data file descriptions ............................................................................................................. 45

FIGURES

1. Map showing locations of monitored basins for urban runoff sampling in Madison, Wis., 1994–95 ....................... 2

2. Land-use maps for the Monroe and Harper Basins in Madison, Wis......................................................................... 4

3. Diagram of street-runoff sampler ............................................................................................................................... 5

4. Diagram of lawn-runoff sampling equipment ............................................................................................................ 7

5–9. Graphs showing:

5. Relations between overhead tree canopy and phosphorus concentrations in street-runoff samples, 

Harper and Monroe Basins, Madison, Wis. ...................................................................................................... 11

6. Phosphorus and suspended-solids concentrations from source areas in the Monroe Basin, Madison, Wis........ 12

7. Phosphorus and suspended-solids concentrations from source areas in the Harper Basin, Madison, Wis. ........ 13

8. Lawn-runoff coefficients used for SLAMM-calculated volumes for basins in Madison, Wis............................ 15

9. Relations between sediment and total-phosphorus mass from street-dirt samples for five particle-size 

fractions for basins in Madison, Wis................................................................................................................. 20

TABLES

1. Land-use characteristics of the Monroe Basin, 1994, and Harper Basin, 1995, in Madison, Wis. .......................... 3

2. Concentrations for suspended solids, total phosphorus, and dissolved phosphorus at the Monroe Basin

and Harper Basin, 1994–95 .................................................................................................................................. 9

3. Rainfall amounts and intensities and total-phosphorus concentrations from lawn-runoff samples for 

Harper and Lakeland Basins, Madison, Wis., 1995.............................................................................................. 10

4. Percentage difference in cumulative modeled water volumes compared with measured outfall water 

volumes using three soil types, Madison, Wis...................................................................................................... 15

5. Percentage difference in cumulative source-area sediment loads, before and after sediment adjustment, 

and modeled and measured sediment loads at the basin outfall, Madison, Wis................................................... 16

6. Suspended-solids concentrations used to calibrate the Source Loading and Management Model for basins

in Madison, Wis. ................................................................................................................................................... 16

7. Percentage difference between cumulative source area versus outfall loads and modeled results versus 

outfall loads, after calibration of the Source Loading and Management Model for basins in Madison, Wis. ..... 17

8. Dissolved-phosphorus concentrations used to calibrate the Source Loading and Management Model for 

basins in Madison, Wis. ........................................................................................................................................ 17

9. Particulate-phosphorus concentrations used to calibrate the Source Loading and Management Model for 

basins in Madison, Wis. ........................................................................................................................................ 17

10. Distribution of loads based on measured values at Monroe and Harper Basins, Madison, Wis.,

and incorporating the suspended-solids adjustment ............................................................................................. 19

11. Distribution of loads from model simulation results at Monroe and Harper Basins, Madison, Wis........................ 19

12. Distribution of loads from monitored source areas only, based on unadjusted concentrations at the 

Monroe and Harper Basins, Madison, Wis........................................................................................................... 19
IV CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS

CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To Obtain

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter

acre 0.4048 hectare

square mile (mi2) 2.590 square kilometer

pound (lb) 453.6 gram

ton (short) 0.9072 megagram (Mg)

quart (qt) 0.9463 liter

Temperature in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) by use of the following equation:

°F = 1.8 (°C) + 32.

Abbreviated water-quality units used in this report: Chemical concentrations and water temperature are given in metric units. Chemical 

concentration is given in milligrams per liter (mg/L) or micrograms per liter (mg/L). Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) of water. One thousand micrograms per 

liter is equivalent to one milligram per liter. For concentrations less than 7,000 mg/L, the numerical value is the same as for concentrations 

in parts per million. Other units of measurement used in this report are microsiemens per centimeter at 25°Celsius (μS/cm), micrometers 

(μm), and bacteria colonies per 100 milliliters of water sample (col/100 mL).
Abstract 1

Abstract

Eutrophication is a common problem for 

lakes in agricultural and urban areas, such as Lakes 

Wingra and Mendota in Madison, Wisconsin. This 

report describes a study to estimate the sources of 

phosphorus, a major contributor to eutrophication, 

to Lakes Wingra and Mendota from two small 

urban residential drainage basins. The Monroe 

Basin empties into Lake Wingra, and the Harper 

Basin into Lake Mendota. Phosphorus data were 

collected from streets, lawns, roofs, driveways, and 

parking lots (source areas) within these two basins 

and were used to estimate loads from each area. In 

addition to the samples collected from these source 

areas, flow-composite samples were collected at 

monitoring stations located at the watershed outfalls (storm sewers); discharge and rainfall also 

were measured. Resulting data were then used to 

calibrate the Source Loading and Management 

Model (SLAMM, version 6.3, copyright 1993, Pitt 

& Vorhees) for conditions in the city of Madison 

and determine within these basins which of the 

source areas are contributing the most phosphorus. 

Water volumes in the calibrated model were 

calculated to within 23 percent and 24 percent of 

those measured at the outfalls of each of the basins. 

These water volumes were applied to the suspended-solids and phosphorus concentrations that 

were used to calibrate SLAMM for suspended-solids and phosphorus loads. Suspended-solids loads 

were calculated to be within 4 percent and 17 percent, total-phosphorus loads within 24 percent and 

28 percent, and dissolved-phosphorus loads within 

9 percent and 10 percent of those measured at the 

storm-sewer outfall at the Monroe and Harper 

basins, respectively. 

Lawns and streets are the largest sources of 

total and dissolved phosphorus in the basins. Their 

combined contribution was approximately 80 percent, with lawns contributing more than the streets. 

Streets were the largest source of suspended solids.

Street-dirt samples were collected using 

industrial vacuum equipment. Leaves in these samples were separated out and the remaining sediment 

was sieved into >250 μm, 250-63 μm, 63-25 μm, 

<25 μm size fractions and were analyzed for total 

phosphorus. Approximately 75 percent of the sediment mass resides in the >250 μm size fractions. 

Less than 5 percent of the mass can be found in the 

particle sizes less than 63 μm. The >250 μm size 

fraction also contributed nearly 50 percent of the 

total-phosphorus mass and the leaf fraction contributed an additional 30 percent. In each particle 

size, approximately 25 percent of the total-phosphorus mass is derived from leaves or other vegetation.

INTRODUCTION

Eutrophication is a common problem for lakes in 

agricultural and urban areas, such as Lakes Wingra and 

Mendota in Madison, Wis. Primary productivity in 

northern temperate lakes is most often limited by phosphorus (Schindler 1974; 1977). Urban runoff has been 

noted to contain high phosphorus concentrations (U.S. 

Environmental Protection Agency, 1983) that may be 

increasing the eutrophication. The focus of the study 

described in this report was to estimate the sources of 

phosphorus to Lakes Wingra and Mendota from two 

small urban residential watersheds in Madison, Wis. 

(fig. 1). This study was done in cooperation with the city 

of Madison and the Wisconsin Department of Natural 

Resources.

Sources of Phosphorus in Stormwater and Street Dirt 

from Two Urban Residential Basins in Madison, 

Wisconsin, 1994–95

By R.J. Waschbusch1, W.R. Selbig1, and R.T. Bannerman2

1

 U.S. Geological Survey, Middleton, Wis.

2

 Wisconsin Department of Natural Resources, Madison, Wis.
2 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95 Odana Rd Midvale Blvd

Nakoma Rd

Speedway Mineral Point Rd

Stoughton Rd

E. Washington Ave

LAKE

MONONA

Beltline Hwy

LA

KE

MENDOTA

LAKE WINGRA

Monroe St MONONA BAY

Regent St

E. Washington Ave

W. Wash. Ave

Northport Dr

North Sherman Ave

 To 

Park St

Atwood Ave

u51

University of Wisconsin

Dane 

County Regional Airport

Williamson St

Winnebago

West Beltline Hwy

West Beltline Hwy

Stoughton Rd

CV

John Nolen Dr

To Stoughton

J

EXPLANATION

1 Monroe Basin2 Harper Basin3 Lakeland Basin Outfall

Wheeler Dr

Green Ave Harper

Farwell Dr

Lakewood

Troy Dr

W I S 

0 1 MILE

0 1 KILOMETER

43°07'30"

89°27'30"

43°02'30"

89°17'

Modified from City of Madison, 1996

u14

Miller Ave

151

12

151

18 12 14 18 151

14

151 12 18

51

51

Glen way

Woodward Dr

2

3

1

1

2

3

Figure 1. Locations of monitored basins for urban runoff sampling in Madison, Wis., 1994–95.
INTRODUCTION 3

Lake Mendota and Lake Wingra are both part of the 

Wisconsin Department of Natural Resources (WDNR) 

Priority Watershed Program (Betz and others, 1997). 

State funding is available to help pay for management 

aimed at reducing the amounts of phosphorus and other 

pollutants discharged to the lakes. The goal of the Lake 

Mendota Priority Watershed Project is to reduce the frequency of nuisance algae blooms in the lake from one 

out of every two days to one out of every five days. To 

accomplish this goal, it is estimated that a 50-percent 

reduction is needed in the amount of phosphorus entering the lake (Betz and others, 1997). To help reach this 

target, the Nonpoint Source Control Plan for the Lake 

Mendota Priority Watershed Project (Betz and others, 

1997) set an objective of reducing phosphorus loading 

to the lake by 20 percent from urban areas. The remaining 30-percent reduction is intended to come from rural 

phosphorus management. 

For this study, phosphorus data were collected from 

five source areas—streets, lawns, roofs, driveways, and 

parking lots—within the two drainage basins from 

urban residential and commercial areas to estimate 

loads from each source area (table 1). Resulting data 

were used to calibrate the Source Loading and Management Model (SLAMM, version 6.3, copyright 1993, Pitt 

& Vorhees) for conditions in the city of Madison and 

determine which source areas are contributing the most 

phosphorus within these basins. The city is planning to 

use SLAMM to target specific source areas for management efforts to meet the 20-percent phosphorus-reduction objective of the priority watershed project and to 

meet requirements of its Wisconsin Pollutant Discharge 

Elimination System stormwater permit. 

Stormwater-runoff samples from source areas and 

the basin outfall were collected from a medium-density 

residential watershed draining to Lake Wingra from 

May to November 1994 and from a medium-density 

residential watershed draining to Lake Mendota from 

June to November 1995. These runoff samples were 

used to estimate the phosphorus and suspended-solids 

load that each of these source areas and basins contributes. In addition, a third basin, the Lakeland Basin that 

drains into Lake Monona, was monitored for lawn runoff in 1995. This basin, which encompasses an older 

section of Madison, was sampled in an attempt to determine whether any difference exists between this section 

of the city (which has older, smaller lawns) and other 

areas of the city.

Study-Area Description

The Monroe Basin, monitored during 1994, drains 

into Lake Wingra. The basin is 232.2 acres, of which 

224.9 acres are residential and 7.3 acres are commercial 

(fig. 2). Lake Wingra has a surface area of 338.9 acres 

(1.37 km2) and a drainage area of 3,889 acres 

(15.74 km2). About 75 percent of the Lake Wingra 

drainage basin is urbanized and about 25 percent is 

composed of forest, prairie, and marsh within the University of Wisconsin Arboretum (Oakes and others, 

1975).

The Harper Basin, monitored during 1995, drains 

into Lake Mendota. The Harper Basin is 41.1 acres, all 

of which is residential land use (fig. 2). Lake Mendota 

has a surface area of 9,859 acres (39.9 km2) and has a 

Table 1. Land-use characteristics of the Monroe Basin, 1994, and Harper Basin, 1995, in Madison, Wis.

[--, source not present]

Monroe Basin Harper Basin

Source area Residential Commercial Residential

Acreage Percent of basin Acreage Percent of basin Acreage Percent of basin

Lawn 119.8 51.5 -- -- 23.6 57.4

Roof 26.5 11.4 2.3 1.0 5.4 13.2

Street 30.5 13.1 1.6 .7 5.3 13.0

Woodlot -- -- -- -- 3.0 7.3

Driveway 10.6 4.6 -- -- 2.1 5.1

Park land 19.3 8.3 -- -- .7 1.7

Sidewalk 12.5 5.4 -- -- .7 1.7

Parking lot .4 .2 3.4 1.5 .3 .7

Railroad bed 5.3 2.3 -- -- -- --

Total 224.9 96.8 7.3 3.2 41.1 100
4 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Figure 2. Land-use maps for the Monroe and Harper Basins in Madison, Wis.

Monroe

Basin

Low-traffic road

with grass ditch

Low-traffic road

without curb and gutter

Low-traffic road

with curb and gutter

Nova Way

Muir Dr.

Luster Ave.

Harper

Basin

Residential roof

Commercial roof

Lawn

Park

Woodlot

Sidewalk

Driveway

Parking lot

Railroad

High-traffic road

Medium-traffic road

0 0.05 0.10

0 0.05 0.10

MILE

KILOMETER

EXPLANATION

0 0.1

0 0.1

MILE

KILOMETER

0.2

0.2

Glenway St

Monroe St

Odana Rd

Harper St

Troy Dr

Nova Way

Muir Dr

Luster Ave

Huron Hill

Spring Trail

Lerdahl Rd

Woodward Dr

Seneca Pl
DATA-COLLECTION EQUIPMENT AND METHODS 5

drainage area of 138,823 acres (561.8 km2) (Lathrop 

and others, 1992). Approximately 20 percent of the 

Lake Mendota drainage area is urban, 57 percent is agricultural, and the remaining 23 percent is grassland/

woodland/marsh/open-water area (Betz and others, 

1997). The Lakeland Basin is approximately 3 mi 

southeast of the Harper Basin.

In addition to the samples collected from source 

areas, a monitoring station was located at each basin 

storm-sewer outfall to collect flow-composite samples 

and to monitor discharge and rainfall. The total rainfall 

amounts for the months of June through October 1994 

at Monroe and July through October 1995 at Harper 

were 9.24 and 10.67 in., respectively. These amounts 

are 64 percent and 71 percent of the average from 1961 

to 1990 (Brian Hahn, National Weather Service, oral 

commun., 1997).

Acknowledgments

We thank all of the volunteers that allowed us to 

install our sampling equipment in their yards, the City 

of Madison Engineering Division and Department of 

Public Health for their efforts in making this study possible, Jeff Beck of the USGS for his exceptional field 

efforts, and Holly Ray and Dr. Bob Pitt at the University 

of Alabama at Birmingham for their work analyzing the 

street-dirt samples. Also, we thank Mary Anne 

Lowndes of the WDNR and Steve Corsi of the USGS 

for insightful comments that have greatly improved the 

report. Lastly, we thank Gail Moede and Aaron Konkol 

at the USGS for their help with the report editing and 

preparation of illustrations. 

DATA-COLLECTION EQUIPMENT AND 

METHODS

Runoff samples were collected from each source 

area by use of sampling equipment slightly modified 

from that described by Bannerman and others (1993). 

Brief descriptions of the sampling equipment follow.

Street samplers. The street samplers were grouted 

into the street approximately 5 ft from the curb (fig. 3). 

The sample bottle was covered with a 6-in. concave 

polycarbonate cap, set flush with the street surface, with 

Figure 3. Diagram of street-runoff sampler.



































3/8-inch thread

for removing cap

Concave 

polycarbonate

cap

6-inch polyvinyl chloride

(PVC) coupling

Polycarbonate set 

screw used to adjust

size of drain hole

1.5-liter sample bottle

6-inch-diameter 

PVC sleeve

Quick-set grout

Undisturbed asphalt

Asphalt subgrade 

material




































































6 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

a center drain hole. The bottle and cap were placed into 

a 6-in. diameter polyvinyl chloride (PVC) sleeve. Water 

flowed over the top of the cap and drained through the 

center hole into a collection bottle. The drain hole could 

be constricted by a set screw that controlled the flow 

rate into the sample bottle. 

Driveway samplers. Runoff water from driveways 

was diverted into a sampler by means of a flat piece of 

clear plastic, 1/4 in. high by 1 in. wide by 3 ft long, 

glued to the surface of the driveway. The sampler consisted of a 1.5-L glass bottle placed in a 10-in.-diameter 

protective PVC sleeve set into the ground next to the 

driveway. A 1/2-in.-diameter silicon tube carried the 

runoff through a plastic cap covering the PVC sleeve 

and into the sampler. During the 1994 field season, the 

tubing emptied directly into the sample bottle, causing 

several sample bottles to overfill. To alleviate this problem, in 1995, the tube emptied onto a polycarbonate cap 

like those used with the street samplers, so that the volume of water entering the sample bottle could be controlled.

Lawn samplers. Lawn sample bottles received 

runoff through two 5-ft pieces of 1/2-in.-diameter PVC 

pipe placed flush with the surface of the ground, on a 

sloping surface, with an angle of about 150 degrees 

between the two pipes (fig. 4). Runoff entered the pipes 

through two slits cut the entire length of pipe. Each pipe 

was wrapped with fiberglass screen to prevent insects 

and large debris from entering. Wooden clothespins 

with small pieces of nylon rope held the pipes in place. 

Water from the pipes flowed into a sampler through a 

notched cap. The sampler was a 1-qt glass bottle placed 

in a 4-in.-diameter protective PVC sleeve. The cap had 

a notch to accommodate silicon tubing, which ran from 

the end of the PVC collector pipes to the sample bottle.

Roof samplers. Roof samplers were designed to 

divert a small portion of the water in the gutter downspout to a sample bottle. A 1/4-in.-diameter vinyl tube 

was attached to the inside of the downspout by means of 

plastic wire ties. Each tube went into a 1.5-L glass sample bottle that was placed in a covered 10-in.-diameter 

protective PVC sleeve. Because of problems with overfilled sample bottles, the design was changed in the 

same manner as the driveway samplers so that the volume of water entering the sample bottle could be controlled.

Parking-lot sampler. The parking-lot sampler collected runoff entering a storm-sewer inlet grate. A small 

portion of the inlet flow was diverted to a sample bottle 

by means of a 6-in. trough made of 1/2-in.-diameter 

PVC pipe cut length-wise and held in place with stainless steel hose clamps attached to the inlet grating. 

Water drained from the trough through a tube to a 

2.5-gal glass sample bottle hanging from the inlet grate. 

No samples were collected from parking lots during 

1995.

Basin storm-sewer outfall samplers. An automated sampling station was placed at the storm-sewer 

outfall of both the Monroe and Harper Basins. In 1994, 

water level in the basin storm-sewer outfall pipe was 

measured with a pressure transducer as water drained 

into a detention pond. Velocity was measured with an 

electromagnetic velocity meter. In 1995, stormwaterrunoff volumes were computed using a modified 

Palmer-Bowlus flume design (Kilpatrick and others, 

1985). The water level was measured one pipe diameter 

(36 in.) upstream from the entrance to the flume using a 

pressure transducer connected to a nitrogen bubble system. This water level was used in the following equation to calculate the total discharge through the flume:

,

where 

Q is discharge, in cubic feet per second,

a is a constant, 3.685,

b is a constant, 1.868,

Ha is the water level above the upstream lip 

of the flume, at a distance of one pipe 

diameter upstream from the flume 

entrance, in feet, and

D is pipe diameter, in feet.

Flow-composite water-quality samples were collected using programmable, refrigerated automatic 

samplers with 3/8-in.-diameter Teflon-lined sample 

tubing. Rainfall was measured using a tipping-bucket 

rain gage and was recorded by a digital data logger. 

Stormwater-Sample Collection and 

Processing Protocols

Sample bottles were placed in the source-area samplers as close to the start of each rain event as possible. 

As the bottles were being deployed, the sampling equipment was rinsed with deionized water to remove any 

accumulated surface dirt. Before the lawn-sampler 

pipes were rinsed, they were cleaned with a small testtube brush. As soon as possible after runoff had 

Q aHa [ ] ⁄ D bD2.5 =
D

ATA-COLLECTIONEQUIPMENTANDMETHODS7Figure 4. Diagram of lawn-runoff sampling equipment.

Silicon tubingstretched over the1/2-inch PVC tube to carry water to the bottle









 













        

Direction of water flow

1/2-inch PVC cap

Top view

Si

1/2-inch PVC tubingwrapped in nylonscreening

Two rows of 2.5-inchslots plunge cut with a table saw to allow the water to enter tube

4-inch Schedule 40polyvinyl chloride (PVC) coupling cutin half with slot cutto accommodate the Tygon tube

4-inch Sched40 PVC coupcut in half witslot cut to accommodatthe Tygon tub

4-inch Schedule40 PVC

4-inch Sche40 PVC

1-quart glassbottle 

Cross-sectional view

5 feet 5 feet

5 feet
8 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

stopped, the sample bottles were collected and the 

approximate volume of water in each bottle was 

recorded.

All the bottles from a given source area were composited by pouring the water from each bottle into a 

5-gal or 1-gal stainless steel, Teflon-coated churn splitter modified from the type described in Ward and Harr 

(1990). The City of Madison Department of Public 

Health Laboratory analyzed a small subsample taken 

from the churn for suspended solids and phosphorus.

Street-Dirt Collection and Analysis

In addition to stormwater-runoff samples, samples 

of street dirt were collected with a 9-gal wet-dry shopvacuum using a 6-in.-wide wand. A section of the street 

was vacuumed from curb to curb, 10 times across each 

of 3 streets in the basin, similar to the technique 

described by Pitt (1979) and Bannerman (1983). Monroe Street, Glenway Street, and Seneca Place/Spring 

Trail/Huron Hill (the latter three are considered one residential street) were sampled during 1994 (fig. 2). 

Woodward Drive, Nova Way, and Luster Avenue were 

sampled during 1995. Woodward Drive did not have 

curbs, so the sample was collected by vacuuming 

between wooden 4-by 4-in. blocks placed at the edge of 

the asphalt on each side of the street. During the fall, 

leaves on the street would often plug the vacuum hose. 

To alleviate this problem, a 6-in. by 2-ft wooden frame 

was placed with the 6-in. side abutting the curb. Before 

vacuuming the inside of the frame, the leaves inside it 

were collected by hand and placed in the vacuum collection bag. Then the street was vacuumed in the normal 

manner.

The dirt samples were dried at 105°C, sieved into 

size fractions of >250 μm, 250-63 μm, 63-25 μm, and 

<25 μm and weighed. The sieved samples were sent to 

the University of Alabama at Birmingham (UAB) for 

phosphorus analysis. In addition to total phosphorus, 

samples collected from the Monroe Basin were analyzed for percentage of vegetative material. Two independent methods were used to determine the percentage 

of vegetative material: thermal chromatography and 

microscopic examination. In thermal chromatography, 

dirt samples were placed in ovens at increasing temperatures and the mass that was lost to incineration was 

determined after each increase in temperature. The 

mass loss was compared to the standard temperatures 

where various substances like leaves, rubber, and paper 

burned off. The sample mass lost at the temperature 

range corresponding to the leaf standards was assumed 

to be vegetation. In microscopic examination, samples 

of the dirt were compared to microscopic pictures of 

vegetation. More details of these methods can be found 

in Ray (1997).

SOURCES OF PHOSPHORUS

Measured Concentrations in Runoff from 

Source Areas

A total of 25 runoff events were monitored at each 

basin (tables A1 and A2). Runoff samples were collected from May to November of 1994 at Monroe and 

from June to November of 1995 at Harper and Lakeland. Driveway samples collected from the Monroe 

Basin were excluded because of problems with the sample bottle overfilling (discussed in the methods section). 

The individual event concentrations for suspended solids, total phosphorus, and dissolved phosphorus at 

Monroe and Harper Basins are listed in appendix tables 

A3–A8. Summary statistics are listed in table 2. Concentrations of these constituents from the Lakeland 

Basin are listed in appendix table A9.

The concentration data from the Monroe and 

Harper Basins seem to exhibit log-normal distributions 

that are consistent with urban-runoff concentration data 

collected during the Nationwide Urban Runoff Project 

(U.S. Environmental Protection Agency, 1983). In such 

cases, the geometric mean is a better estimate of the 

central tendency than the arithmetic mean because the 

geometric mean gives less weight to extremes (Helsel, 

1992). Several of the coefficients of variation in table 2 

have a value greater than 1, indicating substantial variability in concentrations within a source area.

The large variation seen in the source-area concentration data could cast doubt on the predictability of the 

data. For lawn runoff, the difference between geometric 

mean phosphorus concentrations from 1994 to 1995 

was greater than a factor of 2; however, the lawn-runoff 

data collected from the Lakeland Basin are remarkably 

similar to data collected at Harper (table 3), indicating 

that the variation in lawn-runoff phosphorus concentrations is not random. Primary sources of phosphorus, 

such as tree canopy, also could have a large effect on the 

source-area concentrations measured between basins. 

Figure 5 illustrates a trend between the concentration of 

phosphorus and the percentage of overhead tree canopy 
SOURCES OF PHOSPHORUS 9

Table 2. Concentrations for suspended solids, total phosphorus, and dissolved phosphorus at the Monroe Basin and 

Harper Basin, 1994–95

[--, concentrations were not used because of problems with the samplers; -, source area not present in basin; mg/L, milligrams per liter]

Statistic

 Source area

Lawns Feeder

street

Collector

street

Arterial

street Driveways Parkinglots

Pitched

roofs

Flat

roofs

MONROE BASIN

Suspended solids (mg/L)

Geometric mean 59 68 51 65 -- 51 15 18

Coeff. of variation .55 1.17 .97 .92 -- 1.27 .95 1.21

Mean 85 99 67 83 -- 82 85 35

Median 75 60 46 64 -- 44 18 20

Total phosphorus (mg/L)

Geometric mean 0.79 0.40 0.22 0.18 -- 0.10 0.07 0.13

Coeff. of variation .62 1.24 1.23 1.15 -- 1.04 .76 .96

Mean 1.03 .75 .36 .24 -- .14 .09 .2

Median .99 .31 .16 .17 -- .09 .06 .12

Dissolved phosphorus (mg/L)

Geometric mean 0.37 0.16 0.05 0.03 -- 0.02 0.02 0.02

Coeff. of variation .62 1.72 1.47 1.20 -- 1.24 1.22 1.24

Mean .52 .40 .14 .05 -- .04 .03 .04

Median .61 .14 .04 .03 -- .02 .02 .02

HARPER BASIN

Suspended solids (mg/L)

Geometric mean 122 69 - - 34 - 17 -

Coeff. of variation .37 .68 - - .93 - .96 -

Mean 132 98 - - 57 - 25 -

Median 154 88 - - 31 - 17 -

Total phosphorus (mg/L)

Geometric mean 1.61 0.24 - - 0.18 - 0.15 -

Coeff. of variation 1.12 .75 - - .80 - .68 -

Mean 2.34 .31 - - .24 - .19 -

Median 1.54 .22 - - .20 - .15 -

Dissolved phosphorus (mg/L)

Geometric mean 0.77 0.08 - - 0.07 - 0.08 -

Coeff. of variation 1.51 .98 - - 1.0 - .83 -

Mean 1.54 .12 - - .11 - .11 -

Median .81 .08 - - .07 .07 -
10 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

on streets for the Monroe and Harper Basins. Canopy in 

the Monroe Basin tends to be less than 35 percent, 

whereas the percentage of canopy in the Harper Basin 

ranges from 5 to 78 percent. The percentages of overhead tree canopy for all streets in the study are listed in 

appendix table A18. Variation also could be caused by 

meteorological factors like rain depth, intensity, or 

inter-event period or by seasonal variables.

Roof runoff had the lowest geometric mean concentrations of suspended solids, and lawn runoff had the 

highest total and dissolved phosphorus concentrations 

in both the Monroe and Harper Basins (figs. 6 and 7). In 

addition, patterns in geometric mean concentrations 

between source areas within each basin were similar; 

however, their magnitudes were very different. The 

geometric mean concentration of phosphorus for lowtraffic streets in the Monroe Basin were about twice 

those at the Harper Basin. Conversely, geometric mean 

phosphorus concentrations for lawn and roof runoff in 

the Harper Basin were more than twice as high as those 

in the Monroe Basin. The beginning of the sampling 

periods differed by one month between basins (Monroe 

Basin in May and Harper Basin in June), and this difference may have caused some of the variability.

Concentration results for suspended solids and 

phosphorus from earlier source-area studies in Madison, Wis., Marquette, Mich., and Birmingham, Ala. 

(Bannerman and others, 1993; Steuer and others, 1997; 

Pitt and others, 1995), were compared to the concentration results from this study. Suspended-solids concentrations in street-runoff samples collected during the 

other studies were considerably higher than those in 

samples collected for this study. Sandier soils are 

present in Marquette that could partially account for this 

difference. Furthermore, some of the same lawns in the 

Monroe Basin were monitored for phosphorus concentrations in the previous Madison study (Bannerman and 

others, 1993), and both the dissolved and total phosphorus geometric means calculated for that study were 

more than three times higher than those in 1994. 

Because phosphorus concentrations varied highly from 

Monroe and Harper Basins, did not closely agree with 

each other, and did not agree well with previous studies, 

the geometric mean of the combined data collected at 

Monroe and Harper Basins was used for the modeling 

phase of this study.

Calibration of the Source Loading and 

Management Model (SLAMM)

A concentration data base to simulate stormwater 

quality and theoretical runoff coefficients to simulate 

runoff volumes is used in the Source Loading and Management Model (SLAMM). Because large amounts of 

concentration data and runoff information were collected during this study, it was an opportunity to calibrate the model’s concentration data base and improve 

the runoff coefficients with data collected from the 

Monroe and Harper Basins. 

Calibrating SLAMM with concentration and 

water-volume data was a three-step process. First, the 

runoff volume generated by each source area was calibrated (a critical step because an accurate water volume 

Table 3. Rainfall amounts and intensities and total-phosphorus concentrations from lawn-runoff 

samples for Harper and Lakeland Basins, Madison, Wis., 1995

[in/hr, inches per hour; mg/L, milligrams per liter]

HARPER LAKELAND

Start of

rain event

(date)

Rainfall

(inches)

Intensity

(in/hr)

 Total-phosphorus 

concentration

(mg/L)

Rainfall

(inches)

Intensity

(in/hr)

 Total-phosphorus 

concentration

(mg/L)

06/26/95 0.26 0.12 10.72 0.31 0.17 9.05

07/05/95 .36 .62 1.32 .10 .16 2.06

07/15/95 .50 .12 3.61 .80 .10 2.99

07/22/95 .79 .10 1.08 .80 .09 1.35

08/16/95 .61 .43 1.82 .55 .94 2.48

08/16/95 .38 .29 .60 .55 .49 .58

08/28/95 .80 .19 1.39 .67 .15 1.58

10/19/95 .32 .07 2.24 .33 .06 2.59
SOURCES OF PHOSPHORUS 11

Figure 5. Relations between overhead tree canopy and phosphorus concentrations in street-runoff samples, Harper 

and Monroe Basins, Madison, Wis. (R2 = coefficient of determination)

X

X

X

X

X

X

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

DISSOLVED PHOSPHORUS, IN MILLIGRAMS PER LITER

R

2

 = 0.93

DISSOLVED PHOSPHORUS

[

[

[

[

[

[

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER

PERCENT TREE CANOPY

TOTAL PHOSPHORUS

R

2

 = 0.94

linear regression

linear regression

Harper

Monroe

0 10 20 30 40 50 60 70 80

Harper

Monroe
12 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Figure 6. Phosphorus and suspended-solids concentrations from source areas in the Monroe Basin, Madison, Wis.

○

100

200

300

400

500

600

0.5

1.5

2.5

3.5

DISSOLVED PHOSPHORUS 

SUSPENDED SOLIDS 

TOTAL PHOSPHORUS 

0.05

0.1

0.15

0.2

0.25

0.3

0.2

0.4

0.6

0.8

1.4

1.6

TOTAL PHOSPHORUS 

DISSOLVED PHOSPHORUS 

Pitched

Roofs

Flat

 Roofs 

Parking

lots

High-Traffic

Streets

Lawns Low-Traffic

Streets 

Med.-Traffic

Streets

Lawns Low-Traffic

Streets

Med.-Traffic

Streets

Lawns Low-Traffic

Streets

Med.-Traffic

Streets

Pitched

 Roofs 

Flat

 Roofs 

Parking

lots

High-Traffic

Streets

Pitched

Roofs

Flat

Roofs

Parking

lots

High-Traffic

Streets

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

SOURCE AREA SOURCE AREA 

SOURCE AREA 

SOURCE AREA SOURCE AREA 

EXPLANATION 

Source-area

concentration 

Geometric mean 

Monroe Basin 

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SOURCES OF PHOSPHORUS 13

Figure 7. Phosphorus and suspended-solids concentrations from source areas in the Harper Basin, Madison, Wis.

TOTAL PHOSPHORUS 

SUSPENDED SOLIDS 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0

50

100

150

200

250

Geometric mean

0

2

4

6

8

10

12

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

DISSOLVED PHOSPHORUS 

Lawns Streets Driveways Roofs 

Lawns Streets Driveways Roofs 

Lawns Roofs Streets Driveways 

DISSOLVED PHOSPHORUS 

TOTAL PHOSPHORUS 

EXPLANATION 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

CONCENTRATION,

 IN MILLIGRAMS PER LITER 

SOURCE AREA SOURCE AREA 

SOURCE AREA SOURCE AREA 

SOURCE AREA 

Harper Basin 

9

8

7

6

5

4

3

2

1

Source-area 

concentration
14 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

is essential for estimating all pollutant loads). Second, 

sediment was calibrated because sediment concentrations and loads are used in SLAMM to estimate phosphorus loads. The final step was to calibrate the model 

for phosphorus concentrations. The description of each 

basin data file used in SLAMM is given in appendix B.

A systematic procedure was used to calibrate suspended-solids and phosphorus concentrations in 

SLAMM. First, a mass-balance approach compared 

total measured loads from source areas summed over 25 

events to the loads measured at the outfall. Monitored 

loads from source areas were calculated using 

SLAMM-generated water volumes. Individual source 

areas were not equipped to measure runoff volumes during an event. Therefore, the accuracy of source-area 

volumes, as assigned by SLAMM, was subject to agreement with the actual volumes measured at the outfall. If 

the sum of all source-area volumes closely matched 

what was measured at the outfall, the individual sourcearea volumes assigned by SLAMM were assumed to be 

correct. Second, source-area concentrations were 

adjusted to optimize the mass balance. SLAMM was 

adjusted after agreement between measured source-area 

and outfall loads was achieved. 

Water-Volume Calibration

Water-runoff volume from each source area for 

each rain event is calculated with the model. These calculations are based on the amount of rainfall and a runoff coefficient developed for various rainfall depths for 

each source area. Source-area characteristics such as 

imperviousness, connectedness (amount of impervious 

area directly connected to the storm sewer), and infiltration rates on pervious areas were used to develop runoff 

coefficients (Pitt, 1987). The volumetric discharges for 

each source area are then summed for each event. The 

total runoff volume can be decreased in the model by 

using control measures, such as infiltration devices. 

SLAMM was used to estimate runoff volume for 

the 25 storm events from all source areas in each basin. 

The sum of the volumes from all of these source areas 

was compared to the volume measured at the basin 

storm-sewer outfalls for these 25 events. Initially, the 

model overpredicted the water volumes measured at 

Monroe by a total of 55 percent (over the entire study 

period), whereas it underpredicted those measured at 

Harper by only 2 percent. To obtain a balance of overprediction and underprediction between the basins, the 

runoff coefficients were adjusted. Historically, more 

measurements have been made for runoff from impervious surfaces (Pitt, 1987) and more than 50 percent of the 

area within each basin is pervious, mostly because of 

residential lawns. Therefore, it was decided that the runoff coefficients for pervious areas were more uncertain 

and model calibration could benefit from minor adjustments.

Two sets of runoff coefficients are available for 

pervious areas; one is designed to represent clayey soils, 

and the other represents sandy soils. The predicted 

water volumes mentioned above were determined using 

the runoff coefficients for clayey soils (based on soil 

maps). Changing the pervious classification from 

clayey to sandy resulted in SLAMM underprediction of 

water volumes; approximately a 4 percent and a 42 percent underprediction at the Monroe and Harper Basin 

storm-sewer outfalls, respectively. A much better agreement was achieved at Monroe by assuming that the 

original soil classification was incorrect. Sandy and 

clayey runoff coefficients, available to the model, probably represented two extremes, and more realistic runoff coefficients fell somewhere between these two 

coefficients.

Lawn-runoff data collected from Monroe and 

Harper Basins were used to create runoff coefficients 

that more accurately represent the pervious conditions 

found in Madison. First, the rainfall depth sufficient to 

initiate runoff in SLAMM was changed using data on 

the amount of stormwater in the lawn-sample bottles 

after each event. For rainfall amounts less than approximately 0.3 in., the bottles were less than 10 percent 

filled. From this observation, 0.3 in. was established as 

the minimum precipitation required to initiate runoff. 

However, the runoff coefficient table for clayey soils 

used in SLAMM resulted in 10 percent runoff for a rainfall depth of 0.2 in. Hence, SLAMM was changed to initiate runoff at 0.3 in. rather than 0.2 in. of precipitation.

In addition to the change described above, a trialand-error approach was used to change the coefficients 

until optimum agreement was reached between water 

volumes predicted in SLAMM and those measured at 

the Monroe and Harper storm-sewer outfalls. The 

resulting coefficients were between those for sandy and 

clayey soils and were approximately two-thirds the 

value for clayey soils. Figure 8 shows how the new 

“Madison” runoff coefficients compare to the sandy and 

clayey coefficients.

Based on the revised Madison runoff coefficients, 

SLAMM overpredicted storm-sewer outfall volumes at 

Monroe by 23 percent and underpredicted Harper 
SOURCES OF PHOSPHORUS 15

storm-sewer outfall volumes by 24 percent (table 4). 

Event-by-event comparisons are listed in appendix 

tables A10 and A11. The Madison coefficients also produced consistent lawn-runoff contributions in both 

basins, approximately 20 percent of the total volume. It 

is expected that the percentage of lawn contribution 

would be similar for both basins because they have 

nearly the same percentage of lawn area.

Sediment Calibration

Once the runoff volumes were calibrated, SLAMM 

was used to estimate sediment loads for the 25 events in 

each basin. With the exception of streets, a data base of 

sediment concentrations for each source area is used in 

SLAMM and these concentrations are applied to the 

water volumes to derive a load. Sediment concentrations from streets are computed by a wash-off function 

that is related to a street-dirt accumulation rate.

A mass-balance approach was used to test the 

source-area concentrations within each basin with those 

measured at the storm-sewer outfall. Source-area loads 

were computed by multiplying the water volumes produced from SLAMM by the concentrations measured at 

the source areas for each event and then summing these 

event loads. Sidewalks and woodlots were two of the 

larger unmonitored source areas in each basin, accounting for 12 percent and 1 percent of the water volume 

produced at Monroe and 7 percent and 2 percent at 

Harper, respectively. To add sidewalks to the load estimates, concentrations measured at driveways were 

applied to estimates at sidewalks to create a sidewalk 

load. Woodlot concentrations were estimated by use of 

data collected in an undeveloped urban site near SupeTable 4. Percentage difference in cumulative modeled water 

volumes compared with measured outfall water volumes 

using three soil types, Madison, Wis.

[%, percent]

Basin Sandy soils

(%)

Clayey soils

(%)

Madison soils

(%)

Monroe -4 55 23

Harper -42 -2 -24

Figure 8. Lawn-runoff coefficients used for SLAMM-calculated volumes for basins in Madison, Wis. 

(Soil runoff coefficients for Madison are between those for sandy and clayey soils and are approximately

two-thirds the value of clayey soils.)

B

B

B

B

B

B

B

B B B B B B B

J

J

J

J J

J

J

J J J J J

J

J

J

H

H

H

H H

H

H H H H

H

H

H

0 H

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

RUNOFF COEFFICIENT, Rv

PRECIPITATION, IN INCHES

B Sandy soils

J Clayey soils

H Madison soils
16 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

rior, Wis. (Steuer and others, 1997). The source-area 

loads were 39 percent lower and 60 percent lower than 

the measured load at the storm-sewer outfall in the 

Monroe and Harper Basins, respectively. This difference between source-area and storm-sewer outfall loads 

indicates that one or more source areas within each 

basin were not effectively monitored. 

Streets were the most likely source area to be ineffectively monitored. Street samplers were placed 

approximately 5 ft away from the curb to prevent gutter 

flow into the sampler because gutter flow usually contains a mixture of water from several source areas. 

Other street studies (Pitt, 1979) have estimated that 

90 percent of the dirt on residential streets in good condition with little to no parking accumulates within 3 ft 

of the curb. A larger amount of dirt can sometimes collect along the curb itself rather than in the driving lane. 

Some of this dirt could have been deposited on the driving lane, and turbulence from passing vehicles and wind 

may have moved it to the curb. Most street dirt falls 

within 1 to 2 ft of the curb if the driving lane is next to 

the curb (Pitt, 1979). This information suggests that the 

street samplers in the Monroe and Harper Basins were 

too far from the curb (5 ft) to representatively collect the 

particulate dirt from the streets. 

For the reasons previously described, a trial-anderror approach was used to select a street-sediment concentration that more accurately reflected the street sediment entering the storm sewer. The final suspendedsolids concentrations for streets were increased by a 

factor of 5. Applying this factor to the simulated street 

suspended-solids concentration during each storm 

event allowed the sum of source-area loads to be within 

7 percent and 9 percent of the storm-sewer outfall loads 

at Monroe and Harper, respectively (table 5). The geometric means for the revised street suspended-solids 

concentrations were 340 and 325 mg/L for low- and 

high-traffic streets, respectively. These values were 

within 5 percent of those measured at both Marquette, 

Mich. (Steuer and others, 1997), and Madison, Wis. 

(Bannerman and others, 1993).

The geometric means of the observed suspendedsolids concentrations, excluding streets, for the 25 

storm events at Monroe and Harper Basins were placed 

into the SLAMM data base (table 6). These values tend 

to be smaller than those used in previous SLAMM calibrations (appendix table B2). The suspended-solids 

concentrations for streets were not as easily altered 

because they are determined by dirt accumulation and 

wash-off functions in the model. Entering the geometric 

means enabled the model to more accurately predict the 

loads measured at the storm-sewer outfall. After summing the 25 events, sediment loads predicted by 

SLAMM were 17 percent lower at Monroe and 32 percent lower at Harper compared to the measured stormsewer outfall loads.

To improve the match between measured and simulated storm-sewer outfall loads, the delivery coefficients were removed from SLAMM calculations, 

essentially assuming 100-percent delivery from source 

area to storm-sewer outfall. The delivery coefficients 

had been added in a previous calibration study to force 

a match to the storm-sewer outfall numbers. This 

adjustment resulted in a 4 percent and 17 percent undersimulation between storm-sewer outfall loads of suspended solids calculated by SLAMM and those 

measured at the storm-sewer outfall for Monroe and 

Harper, respectively (table 5). Event-by-event comparisons are listed in appendix tables A12 and A13.

Table 5. Percentage difference in cumulative source-area 

sediment loads, before and after sediment adjustment, and 

modeled and measured sediment loads at the basin outfall, 

Madison, Wis.

[Loads computed as suspended solids; %, percent]

Cumulative source area compared

with storm-sewer outfall

Basin

Suspended 

solids before

adjustment

(%)

Suspended 

solids after 

adjustment

(%)

Modeled

compared with 

measured

(%)

Monroe -39 -7 -4

Harper -60 -9 -17

Table 6. Suspended-solids concentrations used to 

calibrate the Source Loading and Management 

Model for basins in Madison, Wis.

[mg/L, milligrams per liter; --, a series of algorithms and 

coefficients are used in the model to calculate a suspendedsolids concentration for street runoff]

Suspended solids (mg/L)

Source area Residential Commercial

Driveways 34 34

Lawns 84 84

Parking lots 51 51

Streets -- --

Woodlots 15 15

Roofs 16 18

Sidewalks 34 34
SOURCES OF PHOSPHORUS 17

Phosphorus Calibration

One objective in calibrating phosphorus concentrations in SLAMM was to ensure that the Monroe and 

Harper Basins were accurately represented by the monitored source areas. The sum of source-area loads for 

total phosphorus for the 25 storm events was nearly 

identical to the storm-sewer outfall load (table 7). The 

difference was larger for dissolved phosphorus, but no 

information was available to determine what adjustments should have been made to reduce the difference. 

For this reason, the unadjusted concentrations were 

entered into the SLAMM data base.

The model simulates total phosphorus loads by 

adding the dissolved phosphorus and particulate phosphorus loads. For all source areas except streets, particulate-phosphorus concentrations were calculated using 

total- and dissolved-phosphorus and sediment concentrations measured at the Monroe and Harper Basins. To 

be consistent with calibration procedures, particulatephosphorus concentration for street runoff was calculated using the adjusted value for sediment (an increase 

by a factor of 5). Changing the phosphorus concentrations resulted in SLAMM undersimulation of dissolved 

and total phosphorus by 9 percent and 24 percent at the 

Monroe storm-sewer outfall and 10 percent and 28 percent at the Harper storm-sewer outfall, respectively. 

Event-by-event comparisons are listed in appendix 

tables A14-A17.

The dissolved- and particulate-phosphorus concentrations entered into the SLAMM data base are listed in 

tables 8 and 9. These phosphorus concentrations can be 

compared to those originally in SLAMM (before Madison data were incorporated), which are listed in appendix table B2. Significant changes in dissolved-phosphorus concentrations (table 8) were observed for lawns 

(from 0.22 to 0.53 mg/L), streets (from 0.39 to 

0.12 mg/L), woodlots (from 0.25 to 0.01 mg/L), and 

sidewalks (from 0.60 to 0.07 mg/L). With the exception 

of streets, where the particulate-phosphorus concentrations in runoff decreased, particulate-phosphorus concentrations increased significantly (table 9). 

Distribution of Source-Area Loads 

The distribution of suspended-solids and total- and 

dissolved-phosphorus loads for source areas in the 

Monroe and Harper Basins using measured source-area 

concentrations multiplied by SLAMM-generated water 

volumes is shown in table 10. The distribution of water 

volumes is nearly identical at Monroe and Harper 

Basins. The percentage of the total basin represented by 

each source area is similar for both basins (table 1); 

thus, one should expect to see similar relative volumes 

of water calculated from both basins. Streets contributed most of the suspended-solids loads at both Monroe 

Table 7. Percentage difference between cumulative source 

area versus outfall loads and modeled results versus outfall 

loads, after calibration of the Source Loading and 

Management Model for basins in Madison, Wis.

[%, percent]

Cumulative source area 

versus

storm-sewer outfall

Model results after

calibration versus

storm-sewer outfall

Basin Phosphorus load

Dissolved

(%)

Total

(%)

Dissolved

(%)

Total

(%)

Monroe 39 -1 -9 -24

Harper 35 4 -10 -28

Table 8. Dissolved-phosphorus concentrations used to 

calibrate the Source Loading and Management Model for 

basins in Madison, Wis.

[mg/L, milligrams per liter]

Dissolved phosphorus (mg/L)

Source-area Residential Commercial

Driveways 0.07 0.07

Lawns .53 .53

Parking lots .02 .02

Streets .12 .03

Woodlots .01 .01

Roofs .04 .02

Sidewalks .07 .07

Table 9. Particulate-phosphorus concentrations used to 

calibrate the Source Loading and Management Model for 

basins in Madison, Wis.

[mg/L, milligrams per liter] 

Particulate phosphorus (mg/L)

Source area Residential Commercial

Driveways 2,649 2,649

Lawns 4,943 4,943

Parking lots 1,467 1,467

Streets 569 409

Woodlots 5,000 5,000

Roofs 3,777 7,946

Sidewalks 2,649 2,649
18 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

and Harper Basins, generating 81 percent and 73 percent, respectively. Lawns contributed more than 10 percent of the solids loads at both basins. The phosphorus 

loading, however, was quite different. Lawns in the 

Harper Basin generate more than two-thirds of the 

phosphorus loads, whereas phosphorus in the Monroe 

Basin is more evenly distributed between lawns and 

streets. These differences in load distribution are the 

result of the measured phosphorus concentrations, especially for lawns, which are much higher for the Harper 

Basin (table 2).

The suspended-solids load distribution at the Monroe Basin in 1994 is similar to the distribution observed 

in a 1991 study (Bannerman and others, 1993). Streets 

contributed 80 percent of the total basin suspended-solids load in 1991 and 81 percent in 1994. Lawns also 

were comparable, contributing 7 percent and 10 percent 

of the total basin suspended-solids load in 1991 and 

1994, respectively. Total and dissolved phosphorus, 

however, were very different. During the 1991 study, 

the proportion of the total-phosphorus load from streets 

(58 percent) outweighed that for lawns (14 percent). 

The same was true in 1991 for dissolved phosphorus, 

where streets produced 46 percent and lawns 22 percent 

of the basin load. However, most total- and dissolvedphosphorus loading in 1994 was attributed to lawns 

rather than streets. Streets and lawns, in 1994, generated 

37 and 44 percent of the total-phosphorus load and 39 

and 45 percent of the dissolved-phosphorus load in the 

Monroe Basin. The difference in distributions between 

the two studies is possibly due to differences in sampling methodology. The street-sampler design was 

modified for the 1994 study to eliminate a first-flush 

effect, where the sample bottle would quickly fill with 

stormwater and act as a sediment trap for the remaining 

duration of the storm event. Also, during the 1994 study, 

25 events were monitored, whereas only 10 events were 

monitored in 1991. This larger sample size in 1994 

improves confidence in the loading-distribution estimates.

Distribution of suspended-solids, total-phosphorus, and dissolved-phosphorus loads estimated by 

SLAMM are given in table 11. The distribution of loads 

is consistent with the distribution of measured loads 

shown in table 10. For each constituent, slightly less 

total load was simulated with SLAMM than calculated 

using the measured concentrations (other than suspended solids from streets), yet the distributions of each 

constituent were similar. Streets and lawns contribute 

nearly all of the suspended-solids load for the entire 

basin. Streets alone contribute more than 75 percent of 

the suspended solids at both Monroe and Harper Basins. 

Additionally, the significance of lawns as generators of 

phosphorus is again noted in SLAMM simulations. 

Lawns in the Harper Basin contribute 52 and 61 percent 

of total and dissolved phosphorus loads, and lawns in 

the Monroe Basin contribute 49 and 57 percent. Streets 

contribute the second largest phosphorus loads (about 

25 percent), whereas driveways and sidewalks combined contribute approximately 10 percent. 

The distribution of suspended solids and total and 

dissolved phosphorus for source areas in the Monroe 

and Harper Basins using measured source-area concentrations multiplied by SLAMM-generated water volumes is shown in table 12. Only loads for the source 

areas measured are shown in table 12; concentrations of 

suspended solids in street runoff have not been adjusted. 

These source areas accounted for 82 and 90 percent of 

the total water volume from the Monroe and Harper 

Basins, respectively.

The suspended-solids distributions shown in table 

12 differ from tables 10 and 11, in that the significance 

of lawns as a source increases and the significance of 

streets as a source decreases. Streets are still the largest 

source of suspended solids in both basins. The phosphorus distributions also change, but not as much as the suspended solids because the measured phosphorus 

concentrations were used in all three tables (tables 10, 

11, and 12). The significance of lawns as a source 

increases slightly, and streets are a slightly larger source 

in some cases, and in others, are slightly smaller 

sources. Results shown in table 12 indicate that the 

adjustments made to suspended-solids concentrations 

in street runoff do not greatly affect the phosphorus distributions in the basins.

Sediment and Phosphorus Mass in Street-Dirt 

Samples

Approximately 75 percent of the total sediment 

mass in the street-dirt samples originated in the 

>250 μm size fraction, whereas the smaller fractions 

(<63 μm) made up less than 5 percent. Material composed of leaves, twigs, and other organic debris also 

were measured, contributing, on average, less than 

10 percent of the total sediment mass of the sample 

(fig. 9). Total sediment mass data for street-runoff samples is given in the appendix tables A19 and A20.
SOURCES OF PHOSPHORUS 19

Table 10. Distribution of loads based on measured values at Monroe and Harper Basins, Madison, Wis., and 

incorporating the suspended-solids adjustment

[N/A, source area not present; %, percent abundance; --, value less than 0.5 percent]

HARPER MONROE

Source area Water 

volume1

(%)

1Water volume totals expressed in cubic feet; all other totals expressed in pounds.

Suspended

solids

(%)

Total 

phosphorus 

(%)

Dissolved

phosphorus 

(%)

Water

volume

(%)

Suspended 

solids

(%)

Total

phosphorus 

(%)

Dissolved 

phosphorus 

(%)

Lawns 21 15 67 71 20 10 44 45

Streets 37 273

2Street-runoff concentrations multiplied by 5.

14 11 38 281 37 39

Driveways 18 7 9 9 12 2 5 4

Sidewalks 7 3 4 3 14 3 5 4

Parking lots 3 1 1 -- 6 2 1 1

Roofs 11 1 3 4 7 -- 1 --

Parks 1 -- 2 2 3 2 7 7

Woodlots 3 -- -- -- N/A N/A N/A N/A

Other N/A N/A N/A N/A 1 -- -- -- 

Total 311,122 3,598 9 5 2,417,341 26,045 70 33

Table 11. Distribution of loads from model simulation results at Monroe and Harper Basins, Madison, Wis.

[N/A, source area not present; %, percent abundance; --, value less than 0.5 percent]

HARPER MONROE

Source area Water 

volume1

(%)

1

Water volume totals expressed in cubic feet; all other totals expressed in pounds.

Suspended

solids 

(%)

Total 

phosphorus 

(%)

Dissolved

phosphorus 

(%)

Water

volume

(%)

Suspended 

solids 

(%)

Total

phosphorus 

(%)

Dissolved 

phosphorus 

(%)

Lawns 21 11 52 61 20 12 49 57

Streets 37 81 32 24 38 77 26 22

Driveways 18 4 8 7 12 3 5 4

Sidewalks 7 1 3 3 14 3 6 5

Parking lots 3 1 1 - 6 2 1 1

Roofs 11 1 3 2 7 1 2 -- 

Parks 1 -- 2 2 3 2 8 9

Woodlots 3 -- 1 -- N/A N/A N/A N/A

Other N/A N/A N/A N/A 1 1 2 2

Total 311,122 3,170 7 4 2,417,341 20,814 60 29

Table 12. Distribution of loads from monitored source areas only, based on unadjusted concentrations at the Monroe

and Harper Basins, Madison, Wis.

[ %, percent abundance; percentage columns may not add up to 100% because of independent rounding]

HARPER MONROE

Source area Water 

volume

(%)

Suspended

solids 

(%)

Total

phosphorus 

(%)

Dissolved

phosphorus 

(%)

Water

volume

(%)

Suspended 

solids 

(%)

Total

phosphorus 

(%)

Dissolved 

phosphorus 

(%)

Lawns 23 41 70 75 24 28 56 69

Streets 41 43 20 15 46 53 33 21

Driveways 20 10 7 6 14 9 7 8

Parking lots 4 3 1 0 7 7 2 1

Roofs 12 3 3 4 9 3 2 1
20 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins in Madison, Wisconsin, 1994–95

Like sediment mass, the largest amount of total 

phosphorus was found in the >250 μm size fraction 

(nearly 50 percent) (fig. 9). Combining this size fraction 

with the leaf fraction, about 80 percent of the total phosphorus is accounted for. The contribution of total phosphorus mass decreased as the size fraction decreased. 

Other studies have shown that large phosphorus concentrations correspond with small particle sizes because 

of the high surface area to mass ratio for small particles 

(Boyd and Sartor, 1972). However, the bulk of the phosphorus load results from the greater particle-size fractions (Ray, 1997). Approximately 25 percent of the total 

phosphorus mass in each size fraction can be attributed 

to leaves (Ray, 1997). Phosphorus data for street-dirt 

samples can be found in the appendix tables A21 and 

A22.

A recent study of particle-size distribution in 

stormwater at the Monroe storm-sewer outfall demonstrated that most of the solids are in the particle sizes 

<63 μm (Greb and Bannerman, 1997). This distribution 

is the opposite of the particle-size distribution observed 

for the street dirt collected in this study. These results 

indicate either a loss of the larger particles somewhere 

between the street and the outfall or a problem in collecting larger particles in the runoff samples. Most of 

the larger particles (>63 μm) might settle out before 

reaching the storm-sewer outfall. Street sweeping, 

resuspension onto street terraces, and catch basins can 

remove these particles from the streets before they reach 

the storm sewer. Also, the transport of large particles in 

a storm sewer is not as efficient as the transport of 

smaller, more mobile particles. Large sediment particles 

may become trapped or part of the bedload before 

reaching the sampler. Bedload is not sampled efficiently 

by the automatic samplers described earlier in this 

report. 

SUMMARY AND CONCLUSIONS

Concentrations of suspended solids, total phosphorus, and dissolved phosphorus were collected from various source areas at two urban residential basins in 

Madison, Wis. To represent a range of source-area concentrations for urban residential basins in Madison, the 

geometric means of the combined concentration data 

from the Monroe and Harper Basins were incorporated 

into the urban-runoff model, SLAMM. 

Figure 9. Relations between sediment and total-phosphorus mass from street-dirt samples for five particle-size fractions for 

basins in Madison, Wis.









































0

10

20

30

40

50

60

70

80

0

10

20

30

40

50

60

70

80

PERCENT MASS

PARTICLE SIZE, IN MICROMETERS





Sediment

Total phosphorus

< 25 25–63 63–250 > 250 Leaves
SELECTED REFERENCES 21

Source-area suspended solids and phosphorus 

loads from the Monroe and Harper Basins were determined based on measured concentrations that were multiplied by water volume estimated by use of SLAMM. 

Collected data were used to calibrate and increase confidence in water volumes, suspended solids, and phosphorus source-area loads estimated by SLAMM. The 

calibrated model calculated water volumes to within 23 

and 24 percent of those measured at the outfalls of the 

Monroe and Harper Basins. These calibrated water volumes were then applied to the calibrated suspendedsolids and phosphorus concentrations entered into the 

SLAMM data bases. Suspended-solids loads were estimated by the calibrated SLAMM to be within 4 and 17 

percent, total-phosphorus loads within 24 and 28 percent, and dissolved-phosphorus loads within 9 and 10 

percent of those measured at the storm-sewer outfall to 

the Monroe and Harper Basins, respectively.

Streets and lawns are the largest contributors of 

suspended-solids, total-phosphorus, and dissolvedphosphorus loads in a residential urban basin. Lawns 

are the largest contributors of total and dissolved phosphorus; however, streets contributed nearly 40 percent 

of the basin load, as seen in the Monroe Basin. Streets 

were found to be the largest source of suspended solids.

There was a large difference between geometric 

mean concentrations of phosphorus in lawn runoff from 

1994 to 1995. Phosphorus data collected from lawns in 

the Harper and Lakeland Basins during 1995 are 

remarkably similar, which suggests that the phosphorus 

concentration in lawn runoff is affected by some variable or variables that are not yet understood.

Street-dirt samples indicate that approximately 75 

percent of the sediment mass resides in the >250 μm 

particle-size fraction. Less than 5 percent of the mass 

can be found in the particle sizes less than 63 μm. The 

>250 μm particle-size fraction also contributed nearly 

50 percent of the total-phosphorus mass, and the leaf 

fraction contributed an additional 30 percent. In each 

particle-size fraction, approximately 25 percent of the 

total-phosphorus mass is derived from leaves or other 

vegetation. 

A possible limitation of this study may be that in 

order for the sum of the source-area loads to match the 

basin-outfall loads, it was assumed that the concentrations of suspended solids in street runoff were about 5 

times higher than the concentrations measured. However, the analysis of load distributions based only on 

unadjusted monitored concentration data shows little 

change in the distributions. In addition, samples from 

more rain events were collected in this study than previous source-area studies. Also, improved data-collection 

equipment were used during this study. Both of these 

factors lead to greater confidence in the study results. 

Most of the measured suspended-solids concentrations were lower than those measured from previous 

studies. However, when comparing concentration 

results in this study to results from earlier studies, it is 

important to note that with the exception of the 

Marquette study, previous studies used earlier generation source-area sampling equipment. In Marquette, 

Mich., the soils are considerably more sandy than those 

in Madison, which may explain why the suspended-solids concentrations determined for the Marquette study 

are higher than those from Madison even though both 

studies used the same sample-collection equipment.

The recalibration of the SLAMM model results in 

an improved model that should more accurately simulate phosphorus and sediment runoff loads in Wisconsin 

than the earlier version of the model. The newly created 

lawn-runoff coefficients for Madison represent a compromise between the two previous soil-type options 

available for model input, which probably represented 

runoff extremes. The runoff coefficients calculated for 

Madison should probably be applied to most urban 

lawns in Wisconsin unless soils are known to be either 

sandy or clayey. The phosphorus- and sediment-concentration data bases created for this study are the largest to date using the most advanced source-area sample 

collection technology available.

SELECTED REFERENCES

Andren, A.W., and Stolzenburg, T.R., 1979, Atmospheric 

deposition of lead and phosphorus on the Menomonee 

River watershed—Volume 8, The IJC Menomonee 

River Watershed Study: U.S. Environmental Protection 

Agency, EPA–905/4–79–029–H, 98 p.

Bannerman, R.T., Baun, K., Bohn, M., Hughes, P.E., and 

Graczyk, D.A., 1983, Evaluation of urban nonpoint 

source pollution management in Milwaukee County, 

Wisconsin—Volume I, Urban stormwater characteristics, pollutant sources and management by street sweeping: U.S. Environmental Protection Agency, Water 

Planning Division, PB–84–114164, 191 p.

Bannerman, R.T., Owens, D.W., Dodds, R.B., and Hornewer, 

N.J., 1993, Sources of pollutants in Wisconsin stormwater: Water Science and Technology, v. 28, no. 3–5, 

p. 241–259.

Betz, C.R., Lowndes, M.A., and Porter, S., 1997, Nonpoint 

source control plan for the Lake Mendota priority water-
22 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

shed project—Project summary: Wisconsin Department 

of Natural Resources, WT–481–97, 16 p.

Cullen, R.S., and Huff, D.D., 1972, Determination of land use 

categories in the Lake Wingra Basin: US-International 

Biological Program, Eastern Deciduous Forest Biome 

Program, Memo Report 72–43, 17 p.

Dong, A., Simsiman, G.V., and Chester, G., 1983, Particle size 

distribution and phosphorus levels in soils, sediment and 

urban dust and dirt samples from the Menomonee River 

watershed, Wisconsin, USA: Water Research, v. 17, 

no. 5, p. 569–577.

Greb, S.R., and Bannerman, R.T., 1997, Influence of particle 

size on wet pond effectiveness: Water Environment 

Research, v. 69, no. 6, p. 1134–1138.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: Amsterdam and New York, Elsevier, 

529 p.

Kilpatrick, F.A., Kaehrle, W.R., Hardee, J., Cordes, E.H., and 

Landers, M.N., 1985, Development and testing of highway storm-sewer flow measurement and recording system: U.S. Geological Survey Water-Resources 

Investigations Report 85–4111, 98 p.

Kunz, K.W., 1980, Atmospheric bulk precipitation in the 

Great Lakes basin: Environment Canada, Scientific 

Series 115, 28 p.

Lathrop, R.C., Nehls, S.B., Brynildson, C.L., and Plass, K.R., 

1992, The fishery of the Yahara Lakes: Wisconsin 

Department of Natural Resources, Technical Bulletin 

181, 214 p.

Legg, A.D., Bannerman, R.T., and Panuska, J., 1996, Variation in the relation of rainfall to runoff from residential 

lawns in Madison, Wisconsin, July and August 1995: 

U.S. Geological Survey Water-Resources Investigations 

Report 96–4196, 11 p.

Murphy, T.J., 1974, Sources of phosphorus inputs from the 

atmosphere and their significance to oligotrophic lakes: 

University of Illinois Water Resources Center, Research 

Report 92, 41 p.

Oakes, E.L., Hendrickson, G.E., and Zuehls, E.E., 1975, 

Hydrology of the Lake Wingra Basin, Dane County, 

Wisconsin: U.S. Geological Survey Water-Resources 

Investigations 17–75, 31 p.

Pitt, R., 1979, Demonstration of nonpoint pollution abatement through improved street and sewerage cleaning: 

Cincinnati, Ohio, U.S. Environmental Protection 

Agency, EPA–600/2–79–161, 270 p.

____1987, Small storm urban flow and particulate washoff 

contributions to storm-sewer outfall discharges: University of Wisconsin–Madison, Dept. of Civil and Environmental Engineering, 513 p.

Pitt, R., Field, R., Lalor, M. and Brown, B. 1995, Urban 

stormwater toxic pollutants—Assessment, sources, and 

treatability: Water Environment Research, v. 67, no. 3, 

p. 260–275.

Prentki, R.T., Rogers, D.S., Watson, V.J., Weiler, P.R., and 

Loucks, O.L., 1977, Summary tables of Lake Wingra 

basin data: University of Wisconsin–Madison, Institute 

for Environmental Studies, IES Report 85, 89 p.

Ray, H., 1997, Street dirt as a phosphorus source in urban 

stormwater: University of Alabama at Birmingham, 

Department of Civil Engineering, 125 p.

Ryden, J., Syers, J. and Harris, R., 1972, Nutrient enrichment 

of runoff waters by soils, phase I—Phosphorus enrichment potential of urban soils in the city of Madison: University of Wisconsin–Madison, Department of Soil 

Science, Technical Report OWRR–A–038–WIS, 70 p.

Sartor, J.D., and Boyd, G.B., 1972, Water pollution aspects of 

street surface contaminants: U.S. Environmental Protection Agency, EPA–R2–72–081, 237 p.

Schindler, D.W., 1974, Eutrophication and recovery in experimental lakes—Implications for lake management: 

Science, v. 184, p. 897–899.

____1977, Evolution of phosphorus limitation in lakes: Science, v. 195, p. 260–262.

Steuer, J.J., Selbig, W.R., and Hornewer, N.J., 1997, Sources 

of contamination in an urban basin in Marquette, Michigan and an analysis of concentrations, loads, and data 

quality: U.S. Geological Survey Water-Resources Investigation Report 97–4242, 25 p.

U.S. Environmental Protection Agency, 1983, Results of the 

Nationwide Urban Runoff Program, volume 1—Final 

report: Water Planning Division, Washington, D.C., 

NTIS PB#84-185552, 200 p.

Ward, J.R., and Harr, C.A., eds., 1990, Methods for collection 

and processing of surface-water and bed-material samples for physical and chemical analyses: U.S.Geological 

Survey Open-File Report 90–140, 71 p.
APPENDIX A 23

APPENDIX A—

Detailed Study Data Tables
24 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A1. Rainfall and runoff statistics for the Monroe Basin, Madison, Wis., 1994

[h, hour; min, minute; in/h, inches per hour; ft3, cubic feet]

Rain start

(date & 24-h time)

Rain end

(date & 24-h time)

Rain duration

(h:min)

Total rain

(inches)

Rainfall intensity

(in/h)

Total

runoff volume

(ft3)

05/23/94 18:03 05/23/94 20:55 02:52 0.27 0.09 41,524

05/25/94 17:09 05/26/94 02:29 09:20 .09 .01 7,059

06/05/94 15:00 06/05/94 16:54 01:54 .11 .06 19,544

06/07/94 11:59 06/07/94 12:13 00:14 .04 .17 2,212

06/11/94 15:14 06/11/94 15:22 00:08 .21 1.62 43,269

06/13/94 01:31 06/13/94 03:43 02:12 .28 .13 38,059

06/18/94 17:33 06/18/94 23:55 06:22 .67 .11 141,091

06/19/94 22:34 06/20/94 04:53 06:19 .24 .04 29,264

06/23/94 07:37 06/24/94 06:06 22:29 1.69 .08 300,067

06/25/94 20:51 06/26/94 02:18 05:27 .65 .12 146,500

06/28/94 02:19 06/28/94 02:26 00:07 .04 .34 5,676

07/14/94 00:37 07/14/94 04:46 04:09 .18 .04 18,948

07/20/94 00:38 07/20/94 07:59 06:21 .46 .07 72,369

07/24/94 19:49 07/24/94 22:16 02:27 .12 .05 7,759

08/03/94 13:38 08/04/94 03:37 13:59 1.73 .12 207,369

08/10/94 05:14 08/10/94 23:52 18:38 1.47 .08 285,708

08/12/94 13:51 08/13/94 02:41 12:50 .12 .01 9,772

08/18/94 04:46 08/18/94 09:51 05:05 .55 .11 112,761

08/30/94 10:33 08/30/94 20:05 09:28 .28 .03 63,884

09/14/94 00:40 09/14/94 10:05 09:25 .45 .05 110,713

09/15/94 20:02 09/16/94 02:07 06:05 .60 .10 134,300

09/22/94 07:40 09/22/94 11:56 04:16 .20 .05 25,514

10/22/94 17:04 10/22/94 17:58 00:54 .04 .04 1,279

11/05/94 11:53 11/06/94 00:44 12:51 .60 .05 107,456

11/13/94 17:17 11/13/94 21:28 04:11 .22 .05 32,633
APPENDIX A 25

Table A2. Rainfall and runoff statistics for the Harper Basin, Madison, Wis., 1995

[h, hour; min, minute; in/h, inches per hour; ft3, cubic feet]

Rain start

(date & 24-h time)

Rain end

(date & 24-h time)

Rain duration

(h:min)

Total rain

(inches)

Rainfall intensity

(in/h)

Total

runoff volume

(ft3)

06/26/95 13:39 06/26/95 15:49 02:10 0.26 0.12 7,111

07/04/95 10:26 07/04/95 17:13 06:47 .17 .03 3,698

07/04/95 23:38 07/05/95 05:10 05:32 .79 .14 30,637

07/05/95 14:26 07/05/95 15:01 00:35 .36 .62 13,945

07/15/95 18:29 07/15/95 22:33 04:04 .50 .12 15,915

07/19/95 13:38 07/19/95 15:15 01:37 .15 .09 3,439

07/19/95 22:02 07/20/95 00:34 02:32 .16 .06 4,847

07/22/95 10:46 07/23/95 02:45 07:45 .79 .10 25,704

07/24/95 09:16 07/24/95 09:54 00:43 .18 .25 4,579

07/25/95 19:04 07/26/95 00:12 05:08 .10 .02 1,331

07/27/95 17:15 07/28/95 00:52 07:37 .24 .03 8,545

07/31/95 13:50 07/31/95 23:09 09:19 .21 .02 7,759

08/16/95 00:35 08/16/95 02:56 02:21 .08 .03 1,020

08/16/95 16:19 08/16/95 17:45 01:26 .61 .43 25,790

08/16/95 23:33 08/17/95 00:51 01:18 .38 .29 17,081

08/19/95 08:59 08/19/95 11:18 02:19 .51 .22 19,336

08/28/95 09:23 08/28/95 13:35 04:12 .80 .19 33,506

08/28/95 20:16 08/29/95 04:17 08:01 .15 .02 4,553

09/07/95 07:34 09/07/95 11:38 04:04 .19 .05 5,867

09/19/95 06:24 09/20/95 01:05 18:41 .74 .04 23,043

09/20/95 18:57 09/21/95 04:11 09:14 .14 .02 2,436

09/30/95 11:05 09/30/95 13:16 02:11 .17 .08 6,402

09/30/95 18:13 10/01/95 04:13 10:00 .22 .02 8,588

10/19/95 14:40 10/19/95 19:27 04:47 .32 .07 12,372

10/31/95 15:51 11/01/95 19:55 24:04 1.28 .05 61,992
26 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A3. Concentrations of total phosphorus at monitored source areas in the Monroe Basin, Madison, Wis., 1994

[All concentrations are in milligrams per liter; n.d., no data]

Date Driveways Lawns Pitched

roofs

Flat

roofs

Parking

lot

Low-traffic

streets

Medium-traffic

streets

High-traffic

streets

Storm-sewer

outfall

05/23/94 1.330 n.d. 0.270 0.330 0.720 2.230 2.040 1.470 1.36

05/25/94 .370 n.d. .040 .180 .080 .730 .930 .180 .67

06/05/94 3.100 n.d. .110 .700 .180 2.100 .750 .350 2.79

06/07/94 .570 n.d. .180 n.d. .230 1.870 .770 .470 1.1

06/11/94 .420 .850 .130 .150 .150 .420 .310 .090 2.39

06/13/94 .230 n.d. .030 .040 .030 .220 .180 .090 .24

06/18/94 2.207 1.425 .112 .170 .243 1.121 .326 .296 .576

06/19/94 .669 n.d. .069 .078 .044 .286 .137 .099 .277

06/23/94 .180 .265 .011 .018 .007 .007 .040 .076 n.d.

06/25/94 .439 .524 .045 .041 .041 .226 .112 .137 n.d.

06/28/94 .416 .079 .109 .491 .116 .313 .141 .160 1.709

07/14/94 .264 n.d. .193 n.d. .080 .473 .107 .113 .424

07/20/94 .203 .949 .060 n.d. .048 .271 .093 .093 .336

07/24/94 .315 n.d. n.d. n.d. .180 .428 .249 .181 .655

08/03/94 .572 2.215 .070 .175 .126 .305 .137 .171 .569

08/10/94 .201 .416 .020 .066 .043 .266 .100 .153 .181

08/12/94 .191 n.d. .053 n.d. .092 .251 .072 .178 .19

08/18/94 .190 1.072 .050 .093 .135 .222 .125 .169 .536

08/30/94 .967 2.168 .049 .098 .072 .387 .108 .159 .596

09/14/94 .227 1.109 .041 .121 .088 .204 n.d. .161 .465

09/15/94 .262 1.031 .031 .046 .152 .211 .096 .108 .40

09/22/94 .348 n.d. .040 .445 .071 .213 .288 .247 .798

10/22/94 1.526 n.d. .240 .475 n.d. 1.763 .407 .440 n.d.

11/05/94 .575 1.482 .168 .116 .255 3.901 .843 .229 1.622

11/13/94 .604 .793 .132 .096 .097 .225 .298 .166 .826
APPENDIX A 27

Table A4. Concentrations of dissolved phosphorus at monitored source areas in the Monroe Basin, Madison, Wis., 1994

[All concentrations are in milligrams per liter; n.d., no data]

Date Driveways Lawns Pitched

roofs

Flat

roofs

Parking

lot

Low-traffic

streets

Medium-traffic

streets

High-traffic

streets

Storm-sewer

outfall

05/23/94 0.248 n.d. n.d. 0.126 0.177 0.710 0.794 0.263 0.682

05/25/94 .083 n.d. 0.010 .021 .039 .233 .383 .070 .333

06/05/94 1.650 n.d. .008 .175 .020 .905 .246 .146 1.2

06/07/94 .189 n.d. .002 n.d. .003 1.050 .149 .027 .033

06/11/94 .181 .664 .004 .020 n.d. n.d. n.d. n.d. .119

06/13/94 .116 n.d. .012 .002 .010 .192 .150 .087 .12

06/18/94 .670 .631 .016 .026 .005 .377 .073 .031 .073

06/19/94 .398 n.d. .022 .080 .049 .147 .080 .033 .09

06/23/94 .021 .115 .006 .005 .007 .021 .023 .024 n.d.

06/25/94 .067 .226 .012 .013 .005 .039 .029 .017 n.d.

06/28/94 .096 .028 .028 n.d. .030 .041 .007 .024 .109

07/14/94 .112 n.d. .103 n.d. .024 .022 .038 .012 .193

07/20/94 .055 .590 .023 n.d. .003 .075 .002 .007 .101

07/24/94 .067 n.d. n.d. n.d. .080 .173 .006 .007 .33

08/03/94 .073 .968 .039 .022 .008 n.d. .004 .020 .175

08/10/94 .048 .229 .015 .015 .008 .161 .021 .029 .079

08/12/94 .066 n.d. .018 n.d. .006 .074 .008 .009 .045

08/18/94 .054 .467 .011 .019 .070 .130 .023 .061 .139

08/30/94 .482 .159 .064 .046 .030 .114 .034 .017 .207

09/14/94 .127 .746 .014 .046 .020 .100 .030 .035 .178

09/15/94 .089 .679 .013 .009 .131 .108 .022 .007 .013

09/22/94 .167 n.d. n.d. n.d. .012 .046 .051 .007 .31

10/22/94 1.362 n.d. .171 n.d. n.d. 1.256 .449 .136 n.d.

11/05/94 .220 1.057 .087 .013 .161 3.147 .568 .076 1.197

11/13/94 .457 .671 .064 .010 .044 .143 .196 .043 .547
28 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A5. Concentrations of total-suspended solids at monitored source areas in the Monroe Basin, Madison, Wis., 1994

[All concentrations are in milligrams per liter; n.d., no data]

Date Driveways Lawns Pitched

roofs

Flat

roofs

Parking

lot

Low-traffic

streets

Medium-traffic

streets

High-traffic

streets

Storm-sewer

outfall

05/23/94 437 n.d. 54 36 251 231 315 412 305

05/25/94 72 n.d. 22 17 94 99 138 65 100

06/05/94 403 n.d. 23 67 109 231 91 76 390

06/07/94 65 n.d. n.d. n.d. 34 59 111 55 101

06/11/94 239 109 90 45 449 568 151 85 1083

06/13/94 209 n.d. 31 27 57 57 n.d. 41 44

06/18/94 807 137 31 30 262 239 115 106 305

06/19/94 177 n.d. 14 15 36 53 25 51 65

06/23/94 187 59 n.d. n.d. 14 31 52 101 270

06/25/94 411 152 7 n.d. 74 83 45 64 n.d.

06/28/94 125 1 2 n.d. n.d. 58 20 15 166

07/14/94 69 n.d. 25 n.d. 29 72 37 36 68

07/20/94 70 61 17 n.d. 34 60 34 31 129

07/24/94 63 n.d. n.d. n.d. 15 36 29 46 32

08/03/94 542 79 4 20 112 106 36 121 285

08/10/94 87 70 18 17 24 30 42 80 60

08/12/94 32 n.d. 7 n.d. 53 50 34 98 56

08/18/94 20 149 6 2 31 49 64 52 372

08/30/94 137 70 4 5 21 94 17 54 254

09/14/94 9 108 n.d. n.d. 44 22 26 54 184

09/15/94 122 125 9 n.d. 54 12 47 47 233

09/22/94 26 n.d. n.d. 167 15 32 55 131 109

10/22/94 67 n.d. 25 67 n.d. 81 75 132 n.d.

11/05/94 155 52 29 2 44 74 99 58 118

11/13/94 82 17 13 5 32 67 39 18 113
APPENDIX A 29

Table A6. Concentrations of total phosphorus at monitored source areas in the Harper Basin, 

Madison, Wis., 1995

[All concentrations are in milligrams per liter; n.d., no data]

Date Driveways Lawns Roofs

Lowtree-canopy

streets

Mediumtree-canopy

streets

Hightree-canopy

streets

Stormsewer

outfall

06/26/95 0.33 10.72 0.54 0.22 0.93 3.30 0.85

07/04/95 .15 n.d. .24 .17 .36 2.37 .4

07/04/95 .14 2.40 .24 .10 .22 .66 .39

07/05/95 .26 1.32 .14 .08 .26 .57 .23

07/15/95 .21 3.61 .39 .20 .42 1.75 .38

07/19/95 .39 n.d. .36 .11 .22 1.15 .3

07/19/95 .12 n.d. .14 .08 .15 .80 .23

07/22/95 .08 1.08 .10 .06 .30 .24 .24

07/24/95 .12 n.d. .21 .09 .14 .57 n.d.

07/25/95 .12 n.d. .11 .12 .22 .52 .16

07/27/95 .16 n.d. .15 .10 .29 .71 .26

07/31/95 .20 n.d. .19 .14 .36 .85 .34

08/16/95 .21 3.81 .26 .30 .66 2.25 .28

08/16/95 .14 1.82 .08 .08 .18 1.70 .325

08/16/95 .05 .60 .04 .03 .07 .46 .18

08/19/95 .37 .50 .09 .02 .11 .36 .27

08/28/95 .58 1.39 .11 .06 .18 .55 1.05

08/28/95 .05 n.d. .10 .04 .07 .74 n.d.

09/07/95 .76 n.d. .11 .10 .37 1.37 .67

09/19/95 .05 .48 .17 .04 .18 .36 .16

09/20/95 .04 n.d. .02 .03 .04 .42 .14

09/30/95 .40 1.69 .32 .15 .36 2.48 .64

09/30/95 .26 n.d. .40 .07 .20 1.28 .3

10/19/95 .69 2.24 .22 .26 .87 1.22 .97

10/31/95 .22 1.13 .05 .05 .63 .25 .22
30 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A7. Concentrations of dissolved phosphorus at monitored source areas in the Harper Basin, 

Madison, Wis., 1995

[All concentrations are in milligrams per liter; <, less than; n.d., no data]

Date Driveways Lawns Roofs

Lowtree-canopy

streets

Mediumtree-canopy

streets

Hightree-canopy

streets

Stormsewer

outfall

06/26/95 0.14 8.77 0.36 0.06 0.45 1.78 0.44

07/04/95 .05 n.d. .12 .04 .13 1.14 .22

07/04/95 .01 1.51 .05 .03 .07 .35 .09

07/05/95 .08 .81 .05 .04 .07 .27 .08

07/15/95 .10 3.12 .22 .09 .13 1.06 .23

07/19/95 .19 n.d. .22 .05 .10 .44 .14

07/19/95 .03 n.d. .04 .02 .04 .16 .08

07/22/95 .07 .62 .05 .01 .05 .13 .09

07/24/95 .03 n.d. .11 .02 .04 .13 n.d.

07/25/95 <.01 n.d. .04 .01 .03 .09 .13

07/27/95 .02 n.d. .07 .02 .14 .28 .12

07/31/95 .06 n.d. .09 .02 .06 .04 .13

08/16/95 .18 1.34 .12 .08 .26 1.02 .19

08/16/95 .04 .40 .03 .02 .06 .34 .115

08/16/95 .02 .17 .04 .01 .04 .08 .09

08/19/95 .19 .29 .04 <.01 .06 .19 .07

08/28/95 .39 1.32 .14 .02 .08 .29 .18

08/28/95 .04 n.d. .06 .02 .03 .44 n.d.

09/07/95 .36 n.d. .05 .05 .14 .68 .24

09/19/95 .02 .19 .13 .02 .10 .18 .08

09/20/95 .02 n.d. .01 .02 .02 .24 .06

09/30/95 .17 1.27 .15 .02 .08 1.44 .26

09/30/95 .03 n.d. .29 .02 .08 .93 .14

10/19/95 .33 n.d. .13 .19 .42 .83 .72

10/31/95 .14 .18 .03 .02 .32 .05 .15
APPENDIX A 31

Table A8. Concentrations of total-suspended solids at monitored source areas in the Harper Basin, 

Madison, Wis., 1995

[All concentrations are in milligrams per liter; n.d., no data; <, less than]

Date Driveways Lawns Roofs

Lowtree-canopy

streets

Mediumtree-canopy

streets

Hightree-canopy

streets

Stormsewer

outfall

06/26/95 163 120 49 116 200 510 160

07/04/95 17 n.d. 14 42 61 132 64

07/04/95 65 172 46 132 139 646 206

07/05/95 93 154 17 60 111 352 170

07/15/95 78 78 34 101 192 182 93

07/19/95 25 n.d. 10 28 39 118 39

07/19/95 19 n.d. 34 59 60 253 81

07/22/95 176 166 16 101 211 40 115

07/24/95 9 n.d. 22 33 35 97 n.d.

07/25/95 15 n.d. 13 70 39 123 20

07/27/95 31 n.d. 21 55 122 101 75

07/31/95 31 n.d. 17 69 149 135 85

08/16/95 32 n.d. 15 114 210 n.d. 11

08/16/95 63 164 18 89 150 786 307

08/16/95 6 50 4 13 18 111 41

08/19/95 29 193 7 23 40 122 641

08/28/95 149 164 10 28 61 123 493

08/28/95 6 n.d. <2 6 8 63 n.d.

09/07/95 52 n.d. 114 62 141 124 152

09/19/95 5 135 4 10 26 50 30

09/20/95 4 n.d. <2 5 6 39 10

09/30/95 92 69 56 85 151 242 271

09/30/95 118 n.d. 26 39 58 217 106

10/19/95 132 178 34 40 132 34 125

10/31/95 26 76 2 11 88 69 36
32 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A9. Concentrations of total and dissolved phosphorus and suspended solids 

from lawn runoff and at the storm-sewer outfall in the Lakeland Basin, Madison, 

Wis., 1995

[All concentrations are in milligrams per liter; n.d., no data]

Sample

date

Dissolved phosphorus Total phosphorus Suspended solids

Lawns Storm-sewer

outfall Lawns Storm-seweroutfall Lawns Storm-seweroutfall

6/26/95 5.46 0.83 9.05 1.74 242 409

7/5/95 1.05 .08 2.06 .40 129 176

7/6/95 n.d. .17 1.51 .47 n.d. 296

7/15/95 2.15 .08 2.99 .46 80 159

7/22/95 .74 .06 1.35 .40 75 132

8/16/95 1.32 .22 2.48 .56 n.d. 67

8/16/95 .30 .10 .58 .33 72 114

8/17/95 .18 .09 .75 .24 35 76

8/20/95 n.d. .12 .72 .26 n.d. 67

8/28/95 1.31 .21 1.58 .37 29 75

9/7/95 3.37 .29 4.68 .55 99 126

9/20/95 .37 .23 1.04 .42 150 30

10/19/95 n.d. 1.12 2.59 1.52 184 64

11/2/95 .18 .29 1.36 .42 108 29
APPENDIX A 33

Table A10. Comparison of water volumes measured at the Monroe

Basin storm-sewer outfall to those simulated by the model after 

calibration, Madison, Wis., 1994

[ft3, cubic feet]

Date Rain depth

(inches)

Measured

storm-sewer 

outfall volumes

(ft3)

Modeled

storm-sewer 

outfall volumes

(ft3)

Percent

difference

05/23/94 0.27 41,524 40,009 -4

05/25/94 .09 7,059 9,525 35

06/05/94 .11 19,544 12,251 -37

06/07/94 .04 2,212 2,672 21

06/11/94 .21 43,269 27,415 -37

06/13/94 .28 38,059 42,313 11

06/18/94 .67 141,091 142,974 1

06/19/94 .24 29,264 33,448 14

06/23/94 1.69 300,067 447,706 49

06/25/94 .65 146,500 137,125 -6

06/28/94 .04 5,676 2,672 -53

07/14/94 .18 18,948 22,300 18

07/20/94 .46 72,369 87,858 21

07/24/94 .12 7,759 13,673 76

08/03/94 1.73 207,369 459,257 122

08/10/94 1.47 285,708 381,356 34

08/12/94 .12 9,772 13,673 40

08/18/94 .55 112,761 109,877 -3

08/30/94 .28 63,884 42,313 -34

09/14/94 .45 110,713 85,509 -23

09/15/94 .60 134,300 122,929 -9

09/22/94 .20 25,514 25,522 0

10/22/94 .04 1,279 2,672 109

11/05/94 .60 107,456 122,929 14

11/13/94 .22 32,633 29,367 -10

Totals 1,964,730 2,417,345 23
34 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A11. Comparison of water volumes measured at the Harper Basin 

storm-sewer outfall to those simulated by the model after calibration, 

Madison, Wis., 1995

[ft3, cubic feet]

Date Rain depth

(inches)

Measured

storm-sewer

outfall volumes

(ft3)

Modeled

storm-sewer

outfall volumes

(ft3)

Percent

difference

6/26/95 0.26 7,111 5,373 -24

7/4/95 .17 3,698 2,925 -21

7/4/95 .79 30,637 26,217 -14

7/5/95 .36 13,945 9,044 -35

7/15/95 .50 15,915 14,091 -12

7/19/95 .15 3,439 2,509 -27

7/19/95 .16 4,847 2,715 -44

7/22/95 .79 25,704 26,217 2

7/24/95 .18 4,579 3,140 -31

7/25/95 .10 1,331 1,520 14

7/27/95 .24 8,545 4,746 -45

7/31/95 .21 7,759 3,872 -50

8/16/95 .08 1,020 1,149 13

8/16/95 .61 25,790 18,220 -29

8/16/95 .38 17,081 9,885 -42

8/19/95 .51 19,336 14,447 -25

8/28/95 .80 33,506 26,652 -21

8/28/95 .15 4,553 2,509 -45

9/7/95 .19 5,867 3,360 -43

9/19/95 .74 23,043 23,884 4

9/20/95 .14 2,436 2,308 -5

9/30/95 .17 6,402 2,925 -54

9/30/95 .22 8,588 4,154 -52

10/19/95 .32 12,372 7,468 -40

10/31/95 1.28 61,992 47,150 -24

Totals 349,496 266,480 -24
APPENDIX A 35

Table A12. Comparison of measured and modeled suspended-solids loads

at the storm-sewer outfall, Monroe Basin, Madison, Wis., 1994

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured

storm-sewer

outfall loads

(lbs)

Modeled

storm-sewer

outfall loads

(lbs)

Percent

difference

05/23/94 0.27 791 602 -24

05/25/94 .09 44 416 844

06/05/94 .11 476 601 26

06/07/94 .04 14 315 2,160

06/11/94 .21 2,930 505 -83

06/13/94 .28 105 803 668

06/18/94 .67 2,690 1,097 -59

06/19/94 .24 119 777 554

06/23/94 1.69 5,060 1,768 -65

06/25/94 .65 n.d. n.d. n.d.

06/28/94 .04 59 237 303

07/14/94 .18 80 1,005 1,150

07/20/94 .46 583 1,241 113

07/24/94 .12 16 913 5,790

08/03/94 1.73 3,690 2,207 -40

08/10/94 1.47 1,070 2,058 92

08/12/94 .12 34 974 2,750

08/18/94 .55 2,620 1,398 -47

08/30/94 .28 1,010 1,219 20

09/14/94 .45 1,270 1,422 12

09/15/94 .60 1,950 1,417 -27

09/22/94 .20 174 1,178 578

10/22/94 .04 n.d. n.d. n.d.

11/05/94 .60 792 1,508 90

11/13/94 .22 230 1,254 445

Total (lbs) 25,800 24,915 -4
36 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A13. Comparison of measured and modeled suspended-solids 

loads at the storm-sewer outfall, Harper Basin, Madison, Wis., 1995

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured

storm-sewer 

outfall loads

(lbs)

Modeled

storm-sewer 

outfall loads

(lbs)

Percent

difference

6/26/95 0.26 71 84 18

7/4/95 .17 15 90 509

7/4/95 .79 394 145 -63

7/5/95 .36 148 88 -41

7/15/95 .50 92 135 46

7/19/95 .15 8 101 1,110

7/19/95 .16 25 95 288

7/22/95 .79 185 157 -15

7/24/95 .18 n.d. n.d. n.d.

7/25/95 .10 2 77 4,530

7/27/95 .24 40 98 145

7/31/95 .21 41 98 138

8/16/95 .08 1 97 13,750

8/16/95 .61 494 192 -61

8/16/95 .38 44 146 234

8/19/95 .51 774 150 -81

8/28/95 .80 1,030 195 -81

8/28/95 .15 n.d. n.d. n.d.

9/7/95 .19 56 136 144

9/19/95 .74 43 213 393

9/20/95 .14 2 137 8,910

9/30/95 .17 108 158 46

9/30/95 .22 57 155 173

10/19/95 .32 97 192 99

10/31/95 1.28 139 285 105

Total (lbs) 3,870 3,224 -17
APPENDIX A 37

Table A14. Comparison of measured and modeled total-phosphorus loads 

at the storm-sewer outfall, Monroe Basin, Madison, Wis., 1994

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured

storm-sewer 

outfall loads

(lbs)

Modeled

storm-sewer 

outfall loads

(lbs)

Percent

difference

05/23/94 0.27 3.53 0.82 -77

05/25/94 .09 .30 .31 4

06/05/94 .11 3.40 .43 -87

06/07/94 .04 .15 .20 30

06/11/94 .21 6.46 .52 -92

06/13/94 .28 .57 .98 72

06/18/94 .67 5.07 3.00 -41

06/19/94 .24 .51 .78 55

06/23/94 1.69 n.d. n.d. n.d.

06/25/94 .65 n.d. n.d. n.d.

06/28/94 .04 .61 .15 -75

07/14/94 .18 .50 .74 47

07/20/94 .46 1.52 2.00 32

07/24/94 .12 .32 .62 95

08/03/94 1.73 7.37 11.00 49

08/10/94 1.47 3.23 10.00 210

08/12/94 .12 .12 .65 464

08/18/94 .55 3.77 3.00 -21

08/30/94 .28 2.38 1.00 -58

09/14/94 .45 3.21 2.00 -38

09/15/94 .60 3.35 3.00 -11

09/22/94 .20 1.27 .86 -32

10/22/94 .04 n.d. n.d. n.d.

11/05/94 .60 10.88 3.00 -72

11/13/94 .22 1.68 .98 -42

Total (lbs) 60.19 46.00 -24
38 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A15. Comparison of measured and modeled total-phosphorus

loads at the storm-sewer outfall, Harper Basin, Madison, Wis., 1995

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured

storm-sewer

outfall loads

(lbs)

Modeled

storm-sewer

outfall loads

(lbs)

Percent

difference

6/26/95 0.26 0.38 0.11 -71

7/4/95 .17 .09 .07 -25

7/4/95 .79 .75 .62 -17

7/5/95 .36 .20 .19 -5

7/15/95 .5 .38 .32 -16

7/19/95 .15 .06 .07 4

7/19/95 .16 .07 .07 -6

7/22/95 .79 .39 .62 61

7/24/95 .18 n.d. n.d. n.d.

7/25/95 .1 .01 .05 253

7/27/95 .24 .14 .09 -32

7/31/95 .21 .16 .08 -53

8/16/95 .08 .02 .05 180

8/16/95 .61 .52 .43 -18

8/16/95 .38 .19 .23 19

8/19/95 .51 .33 .33 0

8/28/95 .8 2.20 .64 -71

8/28/95 .15 n.d. n.d. n.d.

9/7/95 .19 .25 .08 -67

9/19/95 .74 .23 .58 150

9/20/95 .14 .02 .07 241

9/30/95 .17 .26 .09 -67

9/30/95 .22 .16 .10 -38

10/19/95 .32 .75 .18 -76

10/31/95 1.28 .85 1.00 17

Total (lbs) 8.40 6.05 -28
APPENDIX A 39

Table A16. Comparison of measured and modeled dissolved-phosphorus 

loads at the storm-sewer outfall, Monroe Basin, Madison, Wis., 1994

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured

storm-sewer 

outfall loads

(lbs)

Modeled

storm-sewer 

outfall loads

(lbs)

Percent

difference

05/23/94 0.27 1.77 0.32 -82

05/25/94 .09 .15 .05 -65

06/05/94 .11 1.46 .07 -95

06/07/94 .04 .00 .01 212

06/11/94 .21 .32 .16 -49

06/13/94 .28 .29 .35 22

06/18/94 .67 .64 2.00 211

06/19/94 .24 .16 .23 42

06/23/94 1.69 n.d. n.d. n.d.

06/25/94 .65 n.d. n.d. n.d.

06/28/94 .04 .04 .01 -63

07/14/94 .18 .23 .12 -47

07/20/94 .46 .46 .98 114

07/24/94 .12 .16 .07 -54

08/03/94 1.73 2.27 6.00 165

08/10/94 1.47 1.41 5.00 255

08/12/94 .12 .03 .07 170

08/18/94 .55 .98 1.00 2

08/30/94 .28 .83 .35 -58

09/14/94 .45 1.23 .95 -23

09/15/94 .60 .11 1.00 817

09/22/94 .20 .49 .14 -71

10/22/94 .04 n.d. n.d. n.d.

11/05/94 .60 8.03 1.00 -88

11/13/94 .22 1.11 .19 -83

Total (lbs) 22.17 20.07 -9
40 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A17. Comparison of measured and modeled dissolved-phosphorus

loads at the storm-sewer outfall, Harper Basin, Madison, Wis., 1995

[lbs, pounds; n.d., no data]

Date Rain depth

(inches)

Measured 

storm-sewer 

outfall loads

(lbs)

Modeled

storm-sewer 

outfall loads

(lbs)

Percent

difference

6/26/95 0.26 0.20 0.04 -79

7/4/95 .17 .05 .02 -68

7/4/95 .79 .17 .34 95

7/5/95 .36 .07 .09 32

7/15/95 .50 .23 .16 -30

7/19/95 .15 .03 .01 -53

7/19/95 .16 .02 .02 -37

7/22/95 .79 .14 .34 133

7/24/95 .18 n.d. n.d. n.d.

7/25/95 .10 .01 .01 -21

7/27/95 .24 .06 .03 -47

7/31/95 .21 .06 .02 -62

8/16/95 .08 .01 .01 -47

8/16/95 .61 .19 .22 16

8/16/95 .38 .10 .11 9

8/19/95 .51 .08 .16 94

8/28/95 .80 .38 .34 -9

8/28/95 .15 n.d. n.d. n.d.

9/7/95 .19 .09 .02 -79

9/19/95 .74 .12 .30 161

9/20/95 .14 .01 .01 42

9/30/95 .17 .10 .02 -84

9/30/95 .22 .08 .03 -64

10/19/95 .32 .56 .07 -87

10/31/95 1.28 .58 .63 9

Total (lbs) 3.34 2.99 -10

Table A18. Percentage of overhead tree canopy for monitored streets in selected 

basins, Madison, Wis.

[%, percent]

Monroe Basin Harper Basin

Residential

streets

(%)

Glenway

(%)

Monroe

(%)

Nova

(%)

Luster

(%)

Woodward

(%)

33 15 13 5 34 78
APPENDIX A 41

Table A19. Total sediment mass and percentage by size fraction in street-dirt samples in the 

Monroe Basin, Madison, Wis., 1994

[μm, micrometer; >, greater than; %, percent]

Total sediment mass (grams) and percentage of total by size fraction

Date 25 μm 25–63 μm 63–250 μm >250 μm Leaves Total mass

Monroe Street

4/10/94 4.7 25.6 226.8 1,543.2 0.0 1,800.4

.3% 1.4% 12.6% 85.7% .0%

6/3/94 1.4 10.2 45.1 171.4 .2 228.3

.6% 4.5% 19.7% 75.1% .0%

7/15/94 .1 3.6 25.7 98.5 .0 127.9

.0% 2.8% 20.1% 77.0% .0%

8/30/94 .9 4.7 24.3 76.5 .1 106.4

.8% 4.4% 22.8% 71.9% .0%

9/30/94 1.5 11.0 29.2 51.5 .8 94.0

1.5% 11.7% 31.1% 54.8% .9%

10/28/94 .6 4.3 16.6 91.6 1.8 114.8

.5% 3.7% 14.4% 79.8% 1.6%

Sum 9.2 59.7 368.6 2,036.3 2.9 2,476.8

.4% 2.4% 14.9% 82.2% .1%

Glenway

4/10/94 4.2 27.4 239.9 1,152.9 0.7 1,425.1

.3% 1.9% 16.8% 80.9% .0%

6/3/94 2.1 11.9 68.2 246.9 71.9 401.0

.5% 3.0% 17.0% 61.6% 17.9%

7/15/94 .3 3.0 26.0 116.0 2.2 147.4

.2% 2.0% 17.7% 78.7% 1.5%

8/30/94 .7 3.6 30.8 127.5 7.5 170.0

.4% 2.1% 18.1% 75.0% 4.4%

9/30/94 .4 3.7 36.0 137.2 20.5 197.8

.2% 1.9% 18.2% 69.3% 10.4%

10/28/94 .6 3.8 30.2 128.5 353.1 516.3

.1% .7% 5.9% 24.9% 68.4%

Sum 8.3 53.5 432.1 1,912.5 456.2 2,862.6

.3% 1.9% 15.1% 66.8% 15.9%

Residential streets

4/10/94 13.5 113.2 583.5 2,793.0 14.4 3,517.6

.4% 3.2% 16.6% 79.4% .4%

6/3/94 15.7 98.5 491.8 1,777.5 99.7 2,483.2

.6% 4.0% 19.8% 71.6% 4.0%

7/15/94 2.8 17.1 126.1 476.0 6.9 628.9

.4% 2.7% 20.0% 75.7% 1.1%

8/30/94 1.4 7.8 88.5 305.0 57.8 460.5

.3% 1.7% 19.2% 66.2% 12.6%

9/30/94 .5 3.6 27.1 125.0 37.1 193.3

.3% 1.8% 14.0% 64.7% 19.2%

10/28/94 .5 3.3 29.1 174.7 310.2 517.7

.1% .6% 5.6% 33.7% 59.9%

Sum 34.5 243.6 1,346.9 5,654.8 526.5 7,806.2

.4% 3.1% 17.3% 72.4% 6.7%
42 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A20. Total sediment mass and percentage by size fraction in street-dirt samples in 

the Harper Basin, Madison, Wis., 1995

[μm, micrometer; %, percent]

Total sediment mass (grams) and percentage of total by size fraction

Date 25 μm 25–63 μm 63–250 μm >250 μm Leaves Total mass

Nova

6/15/95 10.0 36.6 200.8 276.3 6.4 530.1

1.9% 6.9% 37.9% 52.1% 1.2%

7/13/95 1.7 16.1 106.3 186.9 2.3 313.2

.5% 5.1% 33.9% 59.7% .7%

8/23/95 2.6 16.7 110.3 219.4 6.8 355.9

.7% 4.7% 31.0% 61.6% 1.9%

9/28/95 5.1 8.5 88.0 176.6 4.2 282.4

1.8% 3.0% 31.2% 62.5% 1.5%

10/26/95 .6 8.1 74.6 179.2 24.8 287.4

.2% 2.8% 26.0% 62.4% 8.6%

Sum 20.0 86.1 580.0 1,038.4 44.5 1,769.0

1.1% 4.9% 32.8% 58.7% 2.5%

Luster

6/15/95 16.6 145.9 405.4 557.4 48.9 1,174.2

1.4% 12.4% 34.5% 47.5% 4.2%

7/13/95 3.6 64.7 276.9 373.9 61.6 780.7

.5% 8.3% 35.5% 47.9% 7.9%

8/23/95 7.3 62.3 279.3 465.1 28.7 842.6

.9% 7.4% 33.1% 55.2% 3.4%

9/28/95 4.5 29.7 147.5 222.8 66.3 470.7

.9% 6.3% 31.3% 47.3% 14.1%

10/26/95 2.2 18.2 142.0 222.4 296.2 680.9

.3% 2.7% 20.8% 32.7% 43.5%

Sum 34.1 320.8 1,250.9 1,841.6 501.7 3,949.1

.9% 8.1% 31.7% 46.6% 12.7%

Woodward

6/15/95 7.1 55.1 345.5 999.0 32.9 1,439.6

.5% 3.8% 24.0% 69.4% 2.3%

7/13/95 1.6 13.4 145.3 491.2 14.1 665.5

.2% 2.0% 21.8% 73.8% 2.1%

8/23/95 3.9 18.5 157.6 410.3 5.3 595.5

.7% 3.1% 26.5% 68.9% .9%

9/28/95 2.8 23.0 200.3 469.3 29.7 725.1

.4% 3.2% 27.6% 64.7% 4.1%

10/26/95 1.4 2.3 79.9 514.0 1,144.0 1,741.7

.0% .1% 4.6% 29.5% 65.7%

Sum 16.8 112.3 928.6 2,883.8 1,226.0 5,167.4

.3% 2.2% 18.0% 55.8% 23.7%
APPENDIX A 43

Table A21. Total phosphorus mass by size fraction and percentage of mass by street in street-dirt samples in the Monroe 

Basin, Madison, Wis., 1994

[mg, milligrams; μm, micrometers; <, less than]

Collection

date

Total phosphorus mass (mg) in dirt samples by size fraction

Street <25 μm 25–63 μm 63–250 μm >250 μm Leaves Total Percent by 

street

4/10/94 Monroe Street 1.41 7.30 28.35 263.90 0.00 300.96 31

Glenway 1.20 8.16 47.98 157.95 1.11 216.41 2

Residential 

streets

6.85 46.62 196.64 195.51 5.49 451.10 47

Total 9.46 62.08 272.98 617.36 6.60 968.47 100

6/3/94 Monroe Street .45 3.76 8.87 35.98 .46 49.53 4

Glenway 1.11 7.91 33.02 164.67 125.97 332.68 29

Residential 

streets

3.92 42.76 166.71 419.50 149.15 782.04 67

Total 5.48 54.43 208.60 620.15 275.58 1,164.25 100

7/15/94 Monroe Street .04 1.18 4.21 15.76 .00 21.19 12

Glenway .04 .70 5.05 23.43 2.24 31.45 18

Residential 

streets

1.26 7.34 28.24 79.96 5.38 122.19 70

Total 1.34 9.22 37.50 119.15 7.61 174.82 100

8/30/94 Monroe Street .28 1.60 4.03 10.25 .07 16.22 6

Glenway .16 1.33 7.35 31.48 12.00 52.32 21

Residential 

streets

.39 2.83 18.05 62.23 98.26 181.75 73

Total .83 5.76 29.42 103.96 110.33 250.30 100

9/30/94 Monroe Street .34 2.09 5.58 21.06 .73 29.79 11

Glenway .08 1.09 11.17 59.25 36.78 108.37 40

Residential 

streets

.16 1.34 7.19 30.00 95.12 133.81 49

Total .58 4.52 23.94 110.31 132.63 271.98 100

10/28/94 Monroe Street .18 1.39 5.71 16.95 3.56 27.80 3

Glenway .25 1.88 13.09 112.28 125.00 252.50 28

Residential 

streets

.25 1.67 11.71 126.10 475.23 614.96 69

Total .67 4.94 30.51 255.33 603.79 895.25 100

All event totals

Monroe Street 445.5 12.0%

Glenway 993.7 26.7%

Residential 

streets

2,285.8 61.4%

Total 3,725.1 100.0%
44 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

Table A22. Total phosphorus mass and percentage per square foot of pavement, by size 

fraction, in street-dirt samples in the Monroe Basin, Madison, Wis., 1994

μm, micrometer; <, less than; >, greater than; %, percent; --, no data]

Collection

date

Total phosphorus mass (grams) per square foot of pavement and percentage

by size fraction

<25 μm 25–63 μm 63–250 μm >250 μm Leaves Total

Monroe Street

4/10/94 0.00 0.03 0.10 0.94 -- 1.07

.5% 2.4% 9.4% 87.7% --

6/3/94 .00 .01 .03 .13 0.00 .18

.9% 7.6% 17.9% 72.7% .9%

7/15/94 .00 .00 .02 .06 -- .08

.2% 5.6% 19.9% 74.4% --

8/30/94 .00 .00 .01 .04 .00 .06

1.7% 9.9% 24.8% 63.2% .4%

9/30/94 .00 .00 .02 .08 .00 .11

1.1% 7.0% 18.7% 70.7% 2.4%

10/28/94 .00 .00 .02 .06 .01 .10

.7% 5.0% 20.6% 61.0% 12.8%

Total .00 .06 .20 1.30 .02 1.59

.6% 3.9% 12.7% 81.7% 1.1%

Glenway

4/10/94 0.00 0.04 0.23 0.76 0.00 1.05

.6% 3.8% 22.2% 73.0% .5%

6/3/94 .00 .038 .16 .80 .61 1.61

.3% 2.4% 9.9% 49.5% 37.9%

7/15/94 .00 .00 .02 .11 .01 .15

.1% 2.2% 16.1% 74.5% 7.1%

8/30/94 .00 .00 .04 .15 .06 .25

.3% 2.5% 14.0% 60.2% 22.9%

9/30/94 .00 .00 .05 .29 .18 .52

.0% 1.0% 10.3% 54.7% 33.9%

10/28/94 .00 .00 .06 .54 .60 1.22

.0% .7% 5.2% 44.5% 49.5%

Total .01 .06 .57 2.66 1.47 4.77

.2% 1.3% 11.9% 55.7% 30.8%

Residential streets

4/10/94 0.04 0.29 1.23 1.22 0.03 2.82

1.5% 10.3% 43.6% 43.3% 1.2%

6/3/94 .02 .27 1.04 2.62 .93 4.89

.5% 5.5% 21.3% 53.6% 19.1%

7/15/94 .00 .05 .18 .50 .03 .76

1.0% 6.0% 23.1% 65.4% 4.4%

8/30/94 .00 .02 .11 .39 .61 1.14

.2% 1.6% 9.9% 34.2% 54.1%

9/30/94 .00 .00 .04 .19 .59 .84

.1% 1.0% 5.4% 22.4% 71.1%

10/28/94 .00 .01 .07 .79 2.97 3.84

.0% .3% 1.9% 20.5% 77.3%

Total .08 .64 2.68 5.71 5.18 14.29

.6% 4.5% 18.7% 40.0% 36.3%
APPENDIX B 45

APPENDIX B—

SLAMM Data File Descriptions
46 Sources of Phosphorus in Stormwater and Street Dirt from Two Urban Residential Basins In Madison, Wisconsin, 1994–95

APPENDIX B.

Source Loading and Management Model (SLAMM) Data File Description

 The Monroe and Harper Basins are composed of 232.2 and 41.1 acres of residential and commercial land uses 

(see table 1). Each basin has varying degrees of connectedness within each source area. The more connected a source 

area, the greater the efficiency in transport of water, sediment, and pollutants. In the Harper Basin, 100 percent of 

parking lots and sidewalks are directly connected, whereas 87 percent of driveways and only 13 percent of residential roofs are directly connected, the remainder being partially connected. In the Monroe Basin, 2 percent of residential roofs, 69 percent of driveways, 65 percent of sidewalks, and 100 percent of parking lots and commercial roofs 

are directly connected. Streets are a major influence for water, sediment, and phosphorus in both the Harper and 

Monroe Basins. The physical nature of the streets, as well as the control practices implemented for them, help determine the contribution of each element listed above. The streets of varying traffic density and overhead canopy for 

Monroe and Harper study areas as well as their control practices are described in table B1.
APPENDIX B 47

Table B1. Street descriptions and control practices used for Monroe and Harper Source Loading and Management Model data 

files

[--, no control practice used]

MONROE BASIN HARPER BASIN

Residential Glenway Monroe Street Nova Luster Woodward

Traffic intensity Low Medium High Low Low Low

Overhead tree canopy Medium Medium Medium Low Medium High

Street texture Intermediate Intermediate Intermediate Intermediate Intermediate Smooth

Street length (curbmiles) 2 0.564 0.281 1.58 14.88 0.56

Parking density Light Light Light Light Light Light

Street cleaning -- Every 4 weeks One pass every 

week

Every 4 weeks Every 4 weeks Every 4 weeks

Table B2. Concentrations used by the Source Loading and Management Model prior to calibration with Madison data

[mg/L, milligrams per liter; --, a series of algorithms and coefficients to calculate a street solids concentration are used in model calibration]

Source Area Suspended solids (mg/L) Dissolved phosphorus (mg/L) Particulate phosphorus (mg/L)

Residential Commercial Residential Commercial Residential Commercial

Driveways 276 400 0.10 0.10 580 580

Lawns 63 300 .22 .22 1,250 1,250

Parking lots 991 1,630 .02 .02 580 2,960

Streets -- -- .39 .39 650 650

Woodlots 250 5,000 .25 .25 695 695

Roofs 12 5 .04 .04 1,600 1,000

Sidewalks 12 50 .60 .60 995 995