Water Resources of Monroe 

County, New York, Water 

Years 1997-99, with Emphasis 

on Water Quality in the 

Irondequoit Creek Basin

Atmospheric Deposition, Ground 

Water, Streamflow, Trends in Water 

Quality, and Chemical Loads to 

Irondequoit Bay

U.S. Department of the Interior

U.S. Geological Survey 

In cooperation with Monroe County Department of Health

Water-Resources Investigations Report 02-4221
This page has been left blank intentionally.
i Contents

Water Resources of Monroe County, New York, 

Water Years 1997-99, with Emphasis on 

Water Quality in the Irondequoit Creek Basin

Atmospheric Deposition, Ground Water, Streamflow, 

Trends in Water Quality, and Chemical Loads 

to Irondequoit Bay

By DONALD A. SHERWOOD

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 02-4221

In cooperation with

MONROE COUNTY DEPARTMENT OF HEALTH

Ithaca, New York

2003
ii Contents

U.S. DEPARTMENT OF THE INTERIOR

GAIL NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of trade, product, or firm names in this publication

is for descriptive purposes only and does not imply

endorsement by the U.S. Government

For additional information Copies of this report can be

write to: purchased from:

Subdistrict Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

30 Brown Road Box 25286

Ithaca, NY 14850 Denver, CO 80225
Contents III

CONTENTS

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

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

Purpose and Scope....................................................................................................................................................... 4

Study Area ................................................................................................................................................................... 4

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

Atmospheric Deposition ........................................................................................................................................................ 5

Precipitation Volume.................................................................................................................................................... 6

Chemical Yields ........................................................................................................................................................... 6

Ground Water......................................................................................................................................................................... 8

Water Levels ................................................................................................................................................................ 8

Chemical Concentrations............................................................................................................................................. 9

Spatial Variability .............................................................................................................................................. 9

Temporal Trends .............................................................................................................................................. 13

Surface Water......................................................................................................................................................................... 13

Water Temperature....................................................................................................................................................... 14

Temporal Trends in Streamflow................................................................................................................................... 16

Irondequoit Creek at Blossom Road.................................................................................................................. 16

Allen Creek near Rochester............................................................................................................................... 16

Black Creek at Churchville................................................................................................................................ 19

Chemical Concentrations............................................................................................................................................. 19

Spatial Variability .............................................................................................................................................. 23

Erie (Barge) Canal Diversions................................................................................................................. 23

Irondequoit Creek Basin Sites ................................................................................................................. 26

Western Monroe County Sites................................................................................................................. 30

Temporal Variability .......................................................................................................................................... 30

Temporal Trends ............................................................................................................................................... 31

Irondequoit Creek Basin Sites ................................................................................................................. 33

Northrup Creek and Genesee River......................................................................................................... 33

Chemical Loads and Yields ......................................................................................................................................... 34

Irondequoit Creek Basin Sites ................................................................................................................. 38

Western Monroe County Sites................................................................................................................. 41

Summary and Conclusions .................................................................................................................................................... 42

References Cited.................................................................................................................................................................... 44

Appendix ............................................................................................................................................................................... 47

FIGURES

1. Map showing principal geographic features of Monroe County, N.Y. and locations of streamflow-gaging stations 

in study area ................................................................................................................................................................. 3

2. Map showing locations of streamflow-gaging stations, canal-diversion sites, and atmospheric-deposition 

collection sites within the Irondequoit Creek basin..................................................................................................... 5

3. Bar graph showing ammonia in atmospheric deposition at Mendon Ponds County Park. A. Annual yield 

of ammonia to the Irondequoit Creek basin 1984-99. B. Mean monthly concentration of ammonia in bulk 

atmospheric deposition ................................................................................................................................................ 7

4. Graph showing monthly concentration of dissolved ammonia in bulk atmospheric deposition at Mendon Ponds 

County Park and locally weighted scatterplot smooth (LOWESS) trend line 1984-99............................................... 8

5. Map showing locations of observation wells in Ellison Park ..................................................................................... 9
IV Contents

6. Hydrographs showing water levels in Ellison Park wells, 1985-99 ............................................................................. 10

7. Plot of mean monthly water levels at wells Mo 2 and Mo 3, for 1997-99, with mean monthly,

maximum, and minimum water levels for 1985-96 .................................................................................................... 11

8. Bar graphs showing median concentrations of selected constituents in Ellison Park wells for

period of record through 1996 and for 1997-99........................................................................................................... 12

9. Bar plot of monthly water-temperature range and mean monthly water temperature at four sites in the 

Irondequoit Creek basin and Northrup Creek, water years 1997-99............................................................................ 17

10. Daily mean water temperatures at four sites in the Irondequoit Creek basin and Northrup Creek, water 

years 1997-99. .............................................................................................................................................................. 18

11. Monthly mean flows of three streams in Monroe County, N.Y., water years 1997, 1998, and 1999, in relation to 

normal range (flows between the 25th and 75th percentile) for period of record: A. Irondequoit Creek at 

Blossom Road. B. Allen Creek near Rochester. C. Black Creek at Churchville.......................................................... 20

12. Mean monthly flows of three streams in Monroe County, N.Y., for period of record and three-year period, 

water years 1997-99, in relation to normal range (flows between the 25th and 75th percentile) for period of record: 

A. Irondequoit Creek at Blossom Road. B. Allen Creek near Rochester. C. Black Creek at Churchville................... 21

13. Annual mean flow for Irondequoit Creek at Blossom Road and mean annual flow for period of record .................... 22

14. Annual mean flow for Allen Creek near Rochester and Black Creek at Churchville, with mean annual flow for 

period of record ............................................................................................................................................................ 22

15. Bar graph showing median concentrations of selected constituents at Erie (Barge) Canal diversions at Allen 

Creek and East Branch Allen Creek for period of record through 1999. ..................................................................... 24

16. Bar graph showing median values of instantaneous flow and nutrient loads at Erie (Barge) Canal diversions 

at East Branch Allen Creek and Allen Creek, period of record through 1999 ............................................................. 26

17. Boxplots showing ranges in concentration of selected constituents at four Irondequoit Creek basin sites, 

Northrup Creek and three other sites in western Monoe County, water years 1997-99............................................... 27

18. Bar graph showing median concentration of selected constituents in samples from four Irondequoit Creek 

basin sites and Northrup Creek, for the period of record through 1996 and 1997-99 ................................................. 29

19. Plot showing concentrations of (A) total phosphorus and (B) orthophosphate along with LOWESS 

trendlines, before and after implementation of improved treatment for phosphorus at the Spencerport wastewatertreatment plant, at Northrup Creek, water years 1989-99. ........................................................................................... 35

20. Bar graph showing the annual yield of selected constituents at four sites in the Irondequoit Creek basin and four 

sites in western Monroe County, water years 1997-99. ............................................................................................... 39

TABLES

1. Monthly and annual total precipitation, with 3-year average monthly and normal monthly values, at RochesterMonroe County Airport, water years 1997-99. ........................................................................................................... 6

2. Annual yields of selected constituents in bulk atmospheric deposition at Mendon Ponds County Park, water 

years 1997-99. ............................................................................................................................................................. 7

3. Completion data on wells in Ellison Park .................................................................................................................... 8

4. Descriptive statistics and trends of water levels in Ellison Park wells, period of record through 1999....................... 11

5. Statistically significant differences in median concentration of chemical constituents in paired wells by depth in 

Ellison Park, 1997-99. ................................................................................................................................................. 13

6. Statistically significant (α = 0.05) trends in concentrations of selected ground-water constituents at Ellison Park 

wells, period of record through 1999. ......................................................................................................................... 14

7. Monthly maximum, minimum, and mean water temperature at four Irondequoit Creek basin sites and Northrup 

Creek, water years 1997-99......................................................................................................................................... 15

8. Statistical summary and results of trend tests for streamflow at Northrup Creek and four sites in the Irondequoit 

Creek basin, period of record through 1999................................................................................................................ 19

9. Median concentrations of selected constituents at four sites in the Irondequoit Creek basin and four sites in 

western Monroe County, water years 1997-99 ........................................................................................................... 23

10. Median concentrations of selected constituents at Erie (Barge) Canal diversions on East Branch Allen Creek, Allen 

Creek, and Irondequoit Creek, period of record through 1999 ................................................................................... 25

11. Median values of instantaneous flow and nutrient loads at Erie (Barge) Canal diversions on East Branch Allen 

Creek, and Allen Creek, period of record through 1999. ............................................................................................ 25
Contents V

12. Results of Tukey’s Multiple Comparison Test (MCT) showing statistically significant (α = 0.05) differences in 

mean concentrations of selected constituents among Irondequoit Creek basin sites and Northrup Creek, 

water years 1997-99. ................................................................................................................................................... 28

13. Statistically significant differences between mean concentrations of selected constituents for period of record 

through 1996 and those for 1997-99 at Irondequoit Creek basin sites and Northrup Creek....................................... 30

14. Statistical summary and results of trend tests for selected constituents at four sites in the Irondequoit Creek basin 

for period of record through 1999 ............................................................................................................................... 32

15. Statistical summary and results of trend tests for selected chemical constituents at Northrup Creek and Genesee 

River for period of record through 1999...................................................................................................................... 34

16. Equation parameter estimates showing linear dependence of concentration on flow (β1) and magnitude (β3), 

in percent per year, of estimated trends in loads for selected constituents, and R2 values for concentrations 

and loads at four sites in the Irondequoit Creek basin, Genesee River, and four sites in western Monroe 

County, N.Y., 1997-99. ............................................................................................................................................... 37

17. Annual loads of selected constituents transported by Irondequoit Creek to Irondequoit Bay, water years 

1997-99, and percentage of total annual load transported from February through May ............................................ 38

18. Mean annual yields of selected constituents at four sites in the Irondequoit Creek basin, and four sites in 

western Monroe County, for indicated water years..................................................................................................... 40

19. Median concentrations of selected constituents during the non-navigation season at East Branch Allen Creek 

before and after construction of the detention pond at Jefferson Road. ...................................................................... 41

20. Annual constituent loads with associated error and annual yield, for Genesee River at Charlotte Pump Station, 

water years 1997-99. ................................................................................................................................................... 41

APPENDIX

Monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin and at four sites in 

western Monroe County, water years 1997-99 ............................................................................................................ 47
VI Contents

CONVERSION FACTORS AND VERTICAL DATUM

Multiply By To Obtain

Length

inch (in.) 2.54 centimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

square mile (mi2) 2.59 square kilometer

acre 0.40483 hectare

Flow

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

inch per year (in/yr) 25.4 millimeter per year 

million gallons per day (Mgal/d) 3.785 cubic meters per day

gallons per minute (gal/min) 0.06309 liter per second 

gallons per second (gal/s) 0.0010515 liter per second

Volume

cubic feet (ft3) 0.02832 cubic meters

Temperature

degrees Fahrenheit ( ̊F)  ̊C = 5/9 ( ̊F-32) degrees Celsius 

Specific Conductance

microsiemens per centimeter at 25 ̊ Celsius (μS/cm)

Equivalent Concentration Terms

milligrams per liter (mg/L) = parts per million

micrograms per liter (μg/L) = parts per billion

Load

Tons per day (ton/d) 907.1 kilograms per day

Pounds per square mile (lb/mi2) 0.175 kilograms per square kilometer

Vertical datum: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929

(NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level

nets of the United States and Canada, formerly called Sea Level Datum of 1929.
Abstract 1

Water Resources of Monroe County, New York, 

Water Years 1997-99, with Emphasis on 

Water Quality in the Irondequoit Creek Basin

Atmospheric Deposition, Ground Water, Streamflow, Trends in

Water Quality, and Chemical Loads to Irondequoit Bay

By Donald A. Sherwood

ABSTRACT

Irondequoit Creek drains 169 square miles in 

the eastern part of Monroe County. Over time, 

nutrients transported by Irondequoit Creek to 

Irondequoit Bay on Lake Ontario have 

contributed to the eutrophication of the bay. 

Sewage-treatment-plant effluent, a major source 

of nutrients to the creek and its tributaries, was 

eliminated from the basin in 1979 by diversion to 

a regional wastewater-treatment facility, but 

sediment and contaminants from nonpoint 

sources continue to enter the creek and 

Irondequoit Bay. 

This report, the fourth in a series of reports 

that present interpretive analyses of the 

hydrologic data collected in Monroe County since 

1984, interprets data from four surface-watermonitoring sites in the Irondequoit Creek 

basin—Irondequoit Creek at Railroad Mills, East 

Branch Allen Creek at Pittsford, Allen Creek near 

Rochester, and Irondequoit Creek at Blossom 

Road. It also interprets data from three sites in the 

the Genesee River basin—Oatka Creek at 

Garbutt, Honeoye Creek at Honeoye Falls, and 

Black Creek at Churchville— as well as the 

Genesee River at Charlotte Pump Station, and 

also from a site on Northrup Creek at North 

Greece. The Northrup Creek site drains a 23.5-

square-mile basin in western Monroe County, and 

provides information on surface-water quality in 

streams west of the Genesee River and on loads of 

nutrients delivered to Long Pond, a small 

eutrophic embayment of Lake Ontario. The report 

also includes water-level and water-quality data 

from nine observation wells in Ellison Park, and 

atmospheric-deposition data from a collection site 

at Mendon Ponds County Park.

Average annual loads of some chemical 

constituents in atmospheric deposition for 1997-

99 differed considerably from those for the 

long-term period 1984-96. Ammonia and 

potassium loads for 1997-99 were 144 and 118 

percent greater, respectively, than for the 

previous period. Sodium and ammonia + 

organic nitrogen loads were 87 and 60 percent 

greater, respectively. Average annual loads of 

sulfate and orthophosphate for 1997-99 were 36 

and 30 percent lower, respectively, than for the 

previous period.

Loads of all nutrients deposited on the 

Irondequoit basin from atmospheric sources 

during 1997-99 greatly exceeded those 

transported by Irondequoit Creek. The ammonia 

load deposited on the basin was 139 times the 

load transported at Blossom Road (the most 

downstream site); the ammonia + organic 

nitrogen load was 6.3 times greater, 

orthophosphate 7.5 times greater, total 

phosphorus 1.3 times greater and nitrite + nitrate 

1.5 times greater. Average yields of dissolved 

chloride and dissolved sulfate from atmospheric 
2 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

sources were much smaller than those transported 

by streamflow at Blossom Road—chloride was 

about 2 percent and sulfate about 8 percent of the 

amount transported.

Trends in concentration of chemical 

constituents in surface water generally can be 

attributed to changes in land use, annual and 

seasonal variations in streamflow, and annual 

variations in the application of road salt to county 

highways and roads. 

Concentrations of several constituents in 

streams of the Irondequoit Creek basin showed 

statistically significant (α=0.05) trends from the 

beginning of their period of record through 1999. 

The constituent with the greatest number of 

significant trends was ammonia + organic 

nitrogen, with downward trends ranging from 4.1 

to 5.6 percent per year at Allen Creek, Irondequoit 

Creek at Blossom Road, and East Branch Allen 

Creek. Orthophosphate showed an upward trend 

of 4.1 percent per year at Irondequoit Creek at 

Railroad Mills (the most upstream site). 

Dissolved chloride showed upward trends at 

Railroad Mills, Allen Creek, and Blossom Road. 

No trends in volatile suspended solids were noted 

at any of the four Irondequoit basin sites.

Northrup Creek showed significant 

downward trends in concentrations of ammonia + 

organic nitrogen (3.3 percent per year), total 

phosphorus (3.4 percent per year), and 

orthophosphate (5.5 percent per year), and an 

upward trend for dissolved sulfate (1.8 percent 

per year). The Genesee River at Charlotte Pump 

Station showed downward trends of 6.1 percent 

per year for ammonia + organic nitrogen and 0.1 

percent per year for chloride, and upward trends 

of 1.7 percent per year for total phosphorus and 

6.6 percent per year for orthophosphate. 

Mean annual yields (mass per unit area) of 

most constituents at the Irondequoit Creek basin 

sites were similar to those noted for the previous 

report period (1994-96). East Branch Allen 

Creek showed lower yields of all constituents 

during 1997-99 than previously, even though 

runoff during 1997-99 was greater. These lower 

yields are attributed to the construction of an 

upstream detention basin on East Branch Allen 

Creek in 1995.

Statistical analysis of long-term (greater than 

12 years) streamflow records for unregulated 

streams in Monroe County indicated that annual 

mean flows for water years 1997-99 were in the 

normal range (75th to 25th percentile), although 

Allen Creek continues to show a significant 

downward trend in mean monthly streamflow 

during the 1984-99 water years.

INTRODUCTION

Irondequoit Bay, near the city of Rochester, N.Y., 

(fig. 1) has been eutrophic (overly enriched with 

nutrients) for several decades, largely as a result of 

sewage, sediment, and nutrients that enter the bay 

from Irondequoit Creek. The discharge of sewage to 

Irondequoit Creek was eliminated in 1979, when the 

Monroe County wastewater-treatment facility along 

the shore of Lake Ontario began operation.

Since 1980, the U.S. Geological Survey (USGS) 

has conducted a program in cooperation with the 

Monroe County Health Department (MCHD) and the 

Monroe County Environmental Health Laboratory 

(MCEHL) to collect and analyze water-resources data 

from several sites in Monroe County, particularly the 

Irondequoit Creek basin (fig. 2). Data are analyzed to 

help identify sources of contamination, estimate the 

annual loads of selected constituents at various sites, 

and detect trends in concentration of these constituents 

in the county’s streams and rivers. Although the 

discharge of sewage to Irondequoit Creek was 

eliminated in 1979, data collection has been continued 

in an effort to monitor the chemical quality of the 

creek and its tributaries and to assess the effectiveness 

of current resource-management practices. A similar 

monitoring effort began in 1990 on Northrup Creek at 

North Greece (fig. 1), the main tributary to Long Pond, 

a small, highly eutrophic (Makarewicz and others, 

1990) embayment in western Monroe County along 

the southern edge of Lake Ontario.

During water years1 1980-81, the USGS National 

Urban Runoff Program (NURP) study of the 

1 Water year: the 12-month period from October 1 through 

September 30 of the following year. Thus, the water year 

ending on September 30, 1996, is the 1996 water year. All 

years referenced in this report are water years.
3

p

p

p

p

p0422026250

0423205025

04232050

0423204920

04232034

Northrup

Creek

MONROE

COUNTY

LAKE ONTARIO

Lake Ontario

Plain

NEW YORK

COUNTY ORLEANS

West

Creek

BROCKPORT

HILTON

GENESEE

COUNTY

CHURCHVILLE

04231000

Erie

Canal

Black Creek

ROCHESTER

EMBAYMENT

ROCHESTER

Oatka Creek

SCOTTSVILLE

04230500

LIVINGSTON COUNTY

ONTARIO COUNTY

SPENCERPORT Salmon

Creek

04232000

Genesee

River

Honeoye

Creek

HONEOYE

FALLS

Erie

Irondequoit

Bay

WEBSTER

0423205010

Creek

Allen

Crk.

Creek

Thomas

Creek

PITTSFORD

East Br. Allen

FAIRPORT

EAST

ROCHESTER

Canal

COUNTY

ONTARIO

LOCATION MAP

AREA SHOWN IN FIGURE 2

431510077363501

(Barge)

(Barge)

Long Pond

Braddock Bay

Slater

Creek

WAYNE COUNTY

p

p

p

Iron dequoit

GREECE

St. Lawrence River

p

e

MONROE

COUNTY

04229500

p

EXPLANATION

p STREAMFLOW-GAGING

 STATION

GENESEE RIVER SAMPLING SITE

 AT CHARLOTTE PUMP STA.

CITY OR VILLAGE

BASIN BOUNDARY

ROCHESTER-MONROE

 COUNTY AIRPORT

p

0 5 MILES

0 5 KILOMETERS

78o 77o 50' 40' 30'

43o

25'

20'

43o

10'

15'

5'

Streamflow-gaging stations

Water quality site

431510077363501 Genessee River at Charlotte Pump Station

Base from U.S. Geological Survey

Digital Line Graph, 1:100,000

04232034 Irondequoit Creek at Railroad Mills

04232050 Allen Creek near Rochester

0423204920 East Branch Allen Creek at Pittsford

0423205025 Irondequoit Creek at Empire Boulevard

0423205010 Irondequoit Creek at Blossom Road

0422026250 Northrup Creek at North Greece

04230500 Oatka Creek at Garbutt

04231000 Black Creek at Churchville

04232000 Genesee River at Rochester

04229500 Honeoye Creek at Honeoye Falls

Introduction

Figure 1. Principal geographic features of Monroe County, N.Y. and locations of steamflow-gaging stations in 

study area (from Sherwood, 2001a, fig. 1.)
4 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Irondequoit Creek basin investigated nonpoint-source 

contamination from selected areas representing 

specific land uses. Results of that study provided a 

basis from which changes in the nutrient and chemical 

loads of Irondequoit Creek basin sites could be 

identified. In 1993, the USGS, in cooperation with the 

Monroe County Health Department, began a program 

to analyze hydrologic data collected in Monroe 

County to detect significant temporal trends in the 

concentrations of selected chemical constituents in 

streamflow and ground water. Statistical analysis of 

hydrologic data collected during water years 1984-88 

are presented in Johnston and Sherwood (1996), those 

for water years 1989-93 are given in Sherwood (1999), 

and those for water years 1994-96 are given in 

Sherwood (2000).

Purpose and Scope

This report updates the analysis of hydrologic 

data presented in previous reports and describes the 

hydrologic conditions within Monroe County and the 

Irondequoit Creek basin during water years 1997-99. 

It describes the methods of data analysis and the 

statistical methods used for trend analyses and 

estimation of constituent loads. It provides analysis of 

precipitation volume and chemical quality of bulk 

atmospheric deposition during 1997-99, for 

comparison with data from the three previous periods 

(1984-88, 1989-93, 1994-96), analyzes fluctuations in 

ground-water levels in northern Ellison Park (fig. 2), 

and examines the vertical distribution of chemical 

concentrations in ground water at paired wells. It 

relates streamflow in Monroe County during 1997-99 

to historical streamflow and to streamflow during the 

three previous report periods. It examines waterquality trends in Monroe County and relates chemical 

concentrations in 1997-99 to those of the previous 

three report periods and presents loads and yields of 

selected constituents transported by Irondequoit Creek 

to Irondequoit Bay and by Northrup Creek to Long 

Pond and by the Genesee River to Lake Ontario. 

Monthly and annual loads of selected constituents at 

the Irondequoit basin sites, Oatka Creek, Honeoye 

Creek, Black Creek and Northrup Creek are presented 

in the appendix of this report.

Study area 

Monroe County encompasses 673 mi2 in the 

Lake Ontario Plain region of western New York (fig. 

1) (Heffner and Goodman, 1973). Rochester, the 

county seat and largest city, is in the northern part of 

the county. The Genesee River, which flows 

northward through Rochester into Lake Ontario is the 

largest in Monroe County and has a drainage area of 

2,480 mi2 at its mouth (Wagner and Dixson, 1985). 

Streams in various smaller drainage basins (ranging 

from less than 5 mi2 to about 88 mi2) west of the 

Genesee River flow northeastward into Lake Ontario 

or to one of the many bays of the western part of the 

Rochester Embayment. Streams in small drainage 

basins (ranging from less than 0.2 mi2 to nearly 24 

mi2) east of the Genesee River flow north or 

northwestward into Lake Ontario and the Irondequoit 

Creek basin (169 mi2). 

Irondequoit Creek drains into Lake Ontario 

through Irondequoit Bay (fig. 2). Its drainage basin is 

mostly in eastern Monroe County and includes 

drainage from the east side of the city of Rochester 

and from Ontario and Wayne Counties to the south and 

east. Northrup Creek, drains 23.5 mi2

 in western 

Monroe County, and flows into Long Pond, a small 

embayment on the southern edge of Lake Ontario. A 

more complete description of the Irondequoit Creek 

basin, by Kappel and others (1986), describes 

stormwater and sanitary-sewer systems, drinkingwater supplies, surficial geology, and climate. The 

glacial history and geohydrology of the Irondequoit 

Creek valley are discussed in Kappel and Young 

(1989). Land use is discussed in Johnston and 

Sherwood (1996) and Sherwood (1999).

The Erie (Barge) Canal flows generally 

southeastward through the middle of the county and 

receives flow from the headwater areas the streams 

described above (fig. 1). Diversion structures at 

various points along the canal allow water from the 

canal to augment the flow of these small streams 

during low-flow conditions. The canal intersects the 

Genesee River 11.8 mi upstream from the river’s 

mouth. Water diverted by the canal from Lake Erie is 

discharged into the Genesee River from the west; a 

smaller amount is then diverted from the Genesee 

River eastward into the canal. 
5

VICTOR

77o 37' 30" 30'

43o

15'

10'

05'

43o

42o

55'

22' 30"

Base from U.S. Geological Survey

State base map 1:500,000, 1974

p

.

e

e

e

/

/ /

/

p

WEBSTER

IRONDEQUOIT

BAY

EAST

ROCHESTER

MONROE

COUNTY

COUNTY

ONTARIO

MONROE COUNTY

WAYNE COUNTY

Allen

Creek

East

Br. Allen

Creek

Thomas Creek

Creek

Mendon Ponds

County Park

PITTSFORD

FAIRPORT

Genesee River Basin

04232034

04232050

0423205010

0423205025

LAKE ONTARIO

ROCHESTER

Erie

(Barge)

Canal

Area shown

in Figure 5

0423204920

Iron deq uoit

Ellison Park

Linear Park

Cartersville

0

0

1 2 3 MILES

1 2 3 KILOMETERS

EXPLANATION

STREAMFLOW-GAGING STATION

 AND STATION NUMBER

 (names are given in figure 1) 

STREAMFLOW GAGE WITH

 RAIN GAGE

RAIN GAGE AND ATMOSPHERIC

 WETFALL/DRYFALL COLLECTOR 

BASIN BOUNDARY 

04232034

0423205010

CANAL-DIVERSION SAMPLING

 POINT 

p

.

e

/

Genesee River

Figure 2. Locations of streamflow-gaging stations, canal-diversion sites, and 

atmospheric deposition collection sites within the Irondequoit Creek basin, Monroe 

County, N.Y. (Location is shown in fig. 1. Modified from Sherwood, 1999, fig. 2.)

Atmospheric Deposition

Acknowledgments

Special thanks are extended to 

the personnel of MCEHL for 

assistance in the collection, analysis, 

and verification of the data presented 

herein, and in particular, to Charles 

Knauf and Gary Brown for their 

suggestions and guidance in 

preparing this report.

ATMOSPHERIC 

DEPOSITION

Records of precipitation volume 

collected at the Rochester-Monroe 

County Airport (fig. 1) and 

published by the National Oceanic 

and Atmospheric Administration 

(NOAA) (1983, 1997-99) were used 

with chemical data from Mendon 

Ponds County Park, near the 

southwestern edge of the 

Irondequoit basin (fig. 2), for 

computation of constituent loads 

from atmospheric deposition within 

the Irondequoit Creek basin. The 

Mendon Ponds site was selected to 

represent deposition that is 

unaffected by urban emissions. Data 

from Mendon Ponds County Park 

included wetfall (liquid deposition), 

dustfall (dry deposition, the fraction 

that settles out of the atmosphere as 

dust), and bulk (composite) 

deposition, which consists of the two 

previous forms. The three forms of 

deposition were analyzed for 

common ions, nutrients, and lead, 

and for physical characteristics such 

as pH and specific conductance. The 

values obtained from the bulk 

samples have been used throughout 

this series of reports because bulkdeposition samples seemed to be the 

form most free from occasional 

contamination by birds and insects 

and from collector malfunction, and 

to provide the most reliable results. 

Also, there was not consistent 
6 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

agreement between the sum of the results of the 

wetfall and dryfall samples and the values obtained 

from the bulk samples.

The chemical composition of rainfall is highly 

variable, not only from place to place, but from storm 

to storm in a single area and within individual storm 

systems as well. The conditions that usually produce 

rain—a mingling of air masses of different properties 

and origins—promote a high degree of vertical and 

horizontal variation. Although sampling and analysis 

of atmospheric deposition can provide relatively 

accurate estimates of the amounts of each constituent 

that reaches the land surface, the effect of these 

inputs on the loads transported by streams is 

uncertain because of the interactions of chemicals 

with the land surface after their deposition until they 

enter the streams.

Precipitation Volume

The National Weather Service at the RochesterMonroe County Airport has collected precipitation 

data since May 1, 1929. Monthly total, annual total, 

and average monthly precipitation values for water 

years 1997-99 are shown in table 1; which includes 

"normal" values (mean values calculated from 1961-

90 records). The 3-year average rainfall for 1997-99 

was 38.44 in. (6.48 in. above normal). Several months 

of greater-than-normal precipitation during water year 

1998 resulted in a total annual precipitation of 45.89 

in. (13.93 in. above normal). Precipitation for 1997 

was also above normal (6.82 in.), whereas that for 

1999 was slightly (1.3 in.) below normal. Total 

precipitation for 1997-99 was 19.45 in. above normal.

Chemical Yields

Atmospheric deposition is a major source of 

nutrients, especially nitrogen, to the Irondequoit Creek 

basin. The yields of all nutrients from atmospheric 

sources for 1997-99 (table 2) were greater than the 

yields transported by Irondequoit Creek at its 

downstream end (Blossom Road)2

—ammonia by 

almost 14,000 percent, orthophosphate by 650 percent, 

ammonia + organic nitrogen by 530 percent, and total 

phosphorus and nitrite + nitrate by 30 percent and 50 

percent, respectively. In contrast, yields of chloride 

and sulfate deposited on the Irondequoit Creek basin 

were about 2 percent and 8 percent, respectively, of 

those transported in streamflow at Blossom Road.

Annual yield (load per unit area) from 

atmospheric sources was calculated from the 

following formula:

Yield = CP × conversion factor,

 where: C = concentration, in milligrams per liter; and

 P = precipitation (annual), in inches.

The concentration C is obtained from the 

laboratory analysis of monthly bulk samples. The 

conversion factor transforms the results to the desired 

units of yield, in mass per unit area. The yield is then 

multiplied by drainage area to obtain load. This 

computation assumes that the precipitation recorded at 

the rain gage fell uniformly over the entire area 

represented by that particular gage, which is not 

usually the case and, therefore, the calculated 

chemical load may be subject to some degree of error.

Annual yields of selected constituents from 

atmospheric sources to the Irondequoit Creek basin 

are given in table 2. The most abundant constituent in 

2Table 18 Blossom Road 1997-99 yields multiplied by 

2000 lbs/ton.

Table 1. Monthly and annual total precipitation, with 3-year average monthly and normal monthly values, at RochesterMonroe County Airport, N.Y., water years 1997-99.

[All values are in inches. Location is shown in fig.1.] 

*Normal values are based on the average monthly or annual totals for 1961-90.

Water year

Month

Annual

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept total

1997 5.40 4.12 2.97 2.03 2.40 3.88 1.33 2.12 3.01 1.94 4.22 5.36 38.78

1998 1.94 3.57 2.88 5.63 2.34 3.50 1.81 2.63 7.11 6.09 5.39 3.00 45.89

1999 1.54 1.41 1.60 3.92 .69 3.29 2.07 2.72 2.52 1.78 5.71 3.41 30.66

3-year average 2.96 3.03 2.48 3.86 1.81 3.56 1.74 2.49 4.21 3.27 5.11 3.92 38.44

Normal* 2.44 2.92 2.73 2.08 2.10 2.28 2.61 2.72 3.00 2.71 3.40 2.97 31.96
7

precipitation in Monroe County is dissolved sulfate. 

The average annual yield for water years 1997-99 was 

18,300 lb/mi2

, a 36-percent decrease over the longterm period 1984-96. Lead occurs in the smallest 

amounts (about 32 lb/mi2) and is little changed from 

the long-term average of 32.9 lb/mi2

.

Annual yields of some constituents deposited on 

the Irondequoit Creek basin from atmospheric sources 

during 1997-99 were considerably larger than those 

during 1984-96 (table 2). Atmospheric yields of 

dissolved sodium (87 percent greater), dissolved 

potassium (118 percent), ammonia + organic nitrogen 

(60 percent), ammonia (144 percent) and total zinc (65 

percent) showed considerable increases between the 

long-term averages (1984-96) and 1997-99 averages. 

The increases in these yields are due in part to the 

average annual precipitation for 1997-99 being 20 

percent greater than normal. Yields of sulfate and 

orthophosphate were 36 and 30 percent lower than in 

1984-96, respectively. 

Annual deposition of ammonia on the Irondequoit 

Basin has increased steadily since 1996 (fig. 3). 

Reasons for this increase are difficult to assess. The 

increase may result from increased spring and summer 

application of fertilizer to agricultural areas just 

upwind of the Mendon Ponds deposition collector. In 

agricultural situations, surface volatilization 

(vaporization of urea to ammonia gas which is lost to 

the atmosphere) may occur when urea is applied to 

crop lands (Brown and Johnson, 1996). Surface 

volatilization is usually a problem in areas with high 

temperatures, and soils with a high pH. One of the 

largest sources of ammonia in the atmosphere is 

fertilizers and livestock manure. Atmospheric 

concentrations of ammonia during 1984-99 show a 

clear seasonal pattern with highest concentrations 

during spring and summer, when fertilizer application 

is the heaviest (fig. 3). Long-term monthly 

concentrations of ammonia in bulk atmospheric 

deposition (fig 4.) show a gradual downward trend 

from 1984 through 1993 and then an upward trend 

from 1994 through 1999.

Table 2. Annual yields of selected constituents in bulk atmospheric deposition at Mendon Ponds County Park, Monroe 

County, N.Y., water years 1997-99.

[Yields are in pounds per square mile. Location is shown in fig. 2.]

Water year

Calcium,

dissolved 

Magnesium , 

dissolved 

Sodium, 

dissolved 

 Potassium, 

dissolved 

 Sulfate, 

dissolved 

Chloride, 

dissolved 

Ammonia 

plus 

organic

nitrogen, 

total

Nitrite 

plus 

nitrate, 

total

Ammonia 

nitrogen, 

dissolved

 Phosphorus, 

total

Orthophosphate

Lead, 

total 

recoverable

Zinc, 

total 

recoverable

1997 3,649 809 2,803 2,515 16,936 5,468 5,332 2,985 3,061 444 228 32.9 127

1998 3,888 794 1,798 2,627 23,210 5,137 9,385 3,747 5,273 414 113 22.3 180

1999 3,660 659 1,676 3,530 14,826 4,634 8,223 2,399 5,821 894 248 43.6 709

1997-99 avg. 3,732 754 2,089 2,891 18,324 5,080 7,647 3,043 4,718 584 196 32.9 339

1984-96 avg. 3,272 806 1,116 1,329 28,524 4,913 4,771 2,770 1,932 483 280 31.7 206

Percent 

difference +14 -6.4 +87 +118 -36 +3.4 +60 +9.9 +144 +21 -30 +3.8 +65

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

YEAR

0

6,000

1,000

2,000

3,000

4,000

5,000

ANNUAL YIELD, IN POUNDS PER SQUARE MILE

A. Annual yield of ammonia in bulk atmospheric 

 deposition 1984-99

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 0.2

1.4

0.4

0.6

0.8

1.0

1.2

MEAN MONTHLY CONCENTRATION, 

B. Mean monthly concentration of ammonia in bulk 

IN MILLIGRAMS PER LITER

Figure 3. Ammonia in atmospheric deposition at Mendon 

Ponds County Park, Monroe County, N.Y. A. Annual yield of 

ammonia to the Irondequoit Creek basin 1984-99. B. Mean 

monthly concentration of ammonia in bulk atmospheric 

deposition. (Location is shown in fig. 2.)

Ground Water

 atmospheric deposition 1984-99
8 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

GROUND WATER

Ground-water-level and quality data used in this 

report were obtained from nine observation wells in 

Ellison Park (fig. 5). Water levels were measured 

monthly and recorded to the nearest 0.01 ft. Water 

samples were collected twice each year during 1997-

99 from all wells and analyzed by MCEHL for specific 

conductance, pH, alkalinity, and hardness and 

concentrations of common ions, nutrients, metals, and 

dissolved solids. All wells except Mo 659 are finished 

in the upper (unconfined) part of the aquifer (table 3). 

Water levels and chemical quality at differing depths 

in the aquifer were compared through data from three 

sets of paired wells—Mo 663 and Mo 664, on the 

upper south slope of the buried Pinnacle Hills moraine 

(fig. 5), Mo 665 and Mo 666, on top of the moraine, 

and Mo 667 and Mo 668 on the upper north slope of 

the moraine. 

Water Levels

Water-level data indicate frequent reversals in 

direction of lateral flow toward or away from the 

creek, as well as vertically within the aquifer. 

Recharge to the sand and gravel aquifers in the 

glaciated northeastern United States occurs either by 

direct infiltration of precipitation and surface-water or 

by underflow from the upgradient aquifer system. 

Recharge can also occur through infiltration of surface 

water. Recharge rates are usually highest during the 

spring snowmelt period and are lowest during 

midsummer, when evapotranspiration is greatest (fig. 

6). Substantial recharge also can occur during fall, 

when evapotranspiration decreases.

All wells except Mo 2 and Mo 659 are within the 

flood plain of Irondequoit Creek (fig. 5) and, thus, 

respond to water-level fluctuations in the creek. 

Annual mean water levels in well Mo 3, which is on 

the east bank of Irondequoit Creek, averaged 2.27 ft 

lower than in Mo 2, which is near the east wall of the 

valley and upgradient from Mo 3. Water levels in Mo 2 

during 1985-99 ranged from 1.77 ft below land 

Figure 4. Monthly concentration of dissolved ammonia in bulk atmospheric deposition 

at Mendon Ponds County Park and locally weighted scatterplot smooth (LOWESS) 

trend line, Monroe County, N.Y., water years 1984-99. (LOWESS is described on page 

31. Location is shown in fig. 2.)

LOCALLY WEIGHTED 

AMMONIA, DISSOLVED

SCATTERPLOT SMOOTH

CONCENTRATION, IN MILLIGRAMS PER LITER

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 0

3.5

0.5

1.0

1.5

2.0

2.5

3.0 LOWESS TREND LINE

AMMONIA, DISSOLVED

Table 3. Completion data on wells in Ellison Park, 

Monroe County, N.Y.

[LS, land surface; ft, feet. Locations shown in fig. 5.]

1 U, unconfined; C, confined

2 S & G, sand and gravel; A, alluvium 

Well 

no.

Installation

date

LS 

datum

(ft above 

sea level)

Depth

(ft below 

LS)

Screen

interval

 (ft below

 LS)

Aquifer 

type1 Principal 

aquifer2

Mo 2 9/84 252.60 45 41-45 U S & G

Mo 3 9/84 253.20 16 13.5-16 U A

Mo 659 12/86 266.58 215 80-90

 160-170

C S & G

Mo 663 9/88 251.16 10 7.5-10 U A

Mo 664 9/88 251.18 27 22-27 U A

Mo 665 9/88 254.14 17 12-17 U A

Mo 666 9/88 254.14 27 22-27 U A

Mo 667 9/88 255.38 15 10-15 U A

Mo 668 9/88 255.32 36 31-36 U A
9

77o 32'

43o 10'

9'

31'

EXPLANATION

WETLAND BOUNDARY

Mo 2 OBSERVATION WELL AND IDENTIFICATION NUMBER

ELLISON

PARK

APPROXIMATE BOUNDARY OF ELLISON PARK

ROADS

STREAMFLOW-MEASUREMENT AND WATER-

 QUALITY ANALYSIS SITE.

 Number is USGS streamflow-gaging station number.

BOUNDARY OF PINNACLE HILLS MORAINE

10423205010

.

1000 2000 FEET

0 250 500 METERS

0

Base from scanned U.S. Geological Survey

Rochester East, NY 1:24,000, 1978

Mo 659 Mo 665

Mo 666

Mo 667

Mo 668

Mo 3

Mo 663

Mo 664

Mo 2

Millrace

0423205025

Irondequoit

Bay

Lower

Wetland

Upper

Wetland

Creek

Blossom Road

0423205010

NYS Route 590

Browncroft

Empire

Boulev ard

Boulevard

. .

.

..

.

1

1

Irondequoit

surface to 1.25 ft above, and those in Mo 3 ranged from 

4.17 ft below land surface to 2.03 above. Mean monthly 

water levels at these two wells during 1997-99 were 

within the monthly extremes for the period of record 

(fig. 7) and, except for December and March at Mo 2 

and December at Mo 3, were reasonably close to the 

mean monthly values for the period of record. All wells, 

including Mo 659, which is screened in a confined 

aquifer, showed similar seasonal water-level 

fluctuations and response to recharge. 

Water-level records from the beginning of the 

period of record through 1999 were tested for trends 

through the seasonal Kendall test (Hirsch and others, 

1982), described further on. Two of the nine wells—Mo 

659 and Mo 667—showed statistically significant (α = 

0.05) upward trends in water level for the period of 

record (table 4). 

Chemical Concentrations

 Comparison of water-quality data among wells can 

indicate local differences in water quality within a given 

aquifer, ground-water movement to or from a stream, and 

possible sources of contamination and the degree of 

mixing. Water-quality data also can be used to estimate 

temporal trends in ground-water chemistry at a given 

site. Factors that affect ground-water quality are well 

depth and location, rate and direction of ground-water 

flow (vertical and horizontal), type of aquifer material, 

availability of dissolved oxygen, and precipitation 

amount and intensity.

The Oneway Analysis of Variance (ANOVA) 

combined with Tukey’s multiple comparison test was 

used to identify statistically significant areal differences 

in mean concentration of selected constituents among 

wells, as well as differences in constituent concentration 

with depth at the paired wells. ANOVA is a statistical 

test used to determine the significance of overall 

differences in the means of groups of data, but it does 

not specify which groups are different from the others. 

Tukey’s multiple comparison test is generally used in 

conjunction with ANOVA to indicate which of the 

groups are significantly different from the others, and 

whether the difference is positive or negative. The tests 

were performed on ranked data because water quality 

data are usually not normally distributed.

Spatial Variability

The highest median concentrations of nutrients 

continue to occur in water samples from well Mo 667, 

the shallower (15 ft) of a well pair finished in the 

historic Irondequoit Creek flood-plain sediment (fig. 8). 

Considerable disturbance of this area occurred during 

the construction phase of the Pure Waters sewer project 

and fill and foreign material remaining on the surface 

may affect the water chemistry at this location (Young, 

1993). High concentrations of ammonia and ammonia + 

Figure 5. Locations of observation wells in Ellison Park, 

Monroe County, N.Y. (Modified from Coon, 1996, fig. 2.)

Ground Water
10 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 6. Water levels in Ellison Park wells, Monroe County, N.Y., water years 1985-99. 

(Locations are shown in fig. 5.)

WATER YEAR

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

-4

6

-2

0

2

4

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

15

19

16

17

18

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 6

0

2

4

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

2

8

4

6

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

0

10

2

4

6

8

Mo 2 (depth 45 ft)

Mo 3 (depth 16 ft)

Mo 659 (depth 215 ft)

Mo 663 (depth 10 ft)

Mo 664 (depth 27 ft)

Mo 665 (depth 17 ft)

Mo 666 (depth 27 ft)

Mo 667 (depth 15 ft)

Mo 668 (depth 36 ft)
11

organic nitrogen were also detected at wells Mo 

666 and Mo 668. Mo 668 is the deeper (36 ft) of the 

well pair Mo 667-668, and Mo 666 is near Mo 667. 

Median 1997-99 concentrations of ammonia and 

ammonia + organic nitrogen for well Mo 666 were 

slightly higher than those for the previous period of 

record, whereas those for wells Mo 667 and Mo 

668 were lower. The highest median concentrations 

of nitrite + nitrate (0.64 mg/L) for 1997-99 

occurred at Mo 3, which is affected by Irondequoit 

Creek. Median 1997-99 concentrations of nitrite + 

nitrate for all other wells was at or below the 

detection limit of 0.05 mg/L. Median 

concentrations of total phosphorus for Mo 667 were 

considerably higher than those for any of the other 

wells, but were lower than the median for the 

previous period of record. The lower median 

concentrations for 1997-99 at Mo 667 may reflect a 

lessening of the effect of the disturbed area around 

the well.

Common ion concentrations for 1997-99 were 

again considerably higher at Mo 664 than at any of 

the other wells. Mo 664 is at the upstream edge of 

the buried Pinnacle Hills moraine and is subject to 

an upward flow from a pool of mineralized water 

that has collected at the base of the moraine 

(Young, 1993). Median concentrations of common 

ions for 1997-99 were lower than for the previous 

period of record however, except for dissolved 

sulfate, where the median concentration was 

slightly higher (about 20 mg/L). 

Median concentrations of iron at the 

upgradient wells (Mo 664 - Mo 668), were slightly 

higher for the 1997-99 period than previous period 

of record values at wells Mo 665 and Mo 666 and 

Figure 7. Mean monthly water levels at wells Mo 2 and 

Mo 3, Monroe County, N.Y., for 1997-99, with mean 

monthly, maximum, and minimum water levels for 

1985-96. (Locations are shown in fig. 5.)

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

-1.5

2.0

-1.0

-0.5

0

0.5

1.0

1.5

MO 2

-3

5

-2

-1

0

1

2

3

4

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

EXPLANATION

MEAN MONTHLY (WATER YEARS 1985-96)

MEAN MONTHLY (WATER YEARS 1997-99)

UNSHADED AREA INDICATES HIGHEST AND LOWEST

MONTHLY MEAN WATER LEVEL FOR 1985-96

Table 4. Descriptive statistics and trends of water levels in Ellison Park wells, Monroe County, N.Y., period of record 

through 1999. 

[Values are in feet below land surface except as noted. p, significance of trend. Bold type indicates trend is statistically significant 

at α = 0.05. Well locations are shown in fig. 5.] 

Descriptive statistics Trend 

Well no.

Period of 

Record Max Min Mean

25th

percentile

50th percentile

(median)

75th

percentile

Units per 

year

Percent 

per year p

Mo 2 1985-99 -1.25 1.77 0.52 1.00 0.60 0.12 0.02 0.52 0.108

Mo 3 1985-99 -2.03 4.17 2.79 3.41 3.00 2.37 .02 .60 .140

Mo 659 1987-99 15.89 18.21 17.18 17.54 17.25 16.85 .02 .11 .051

Mo 663 1989-99 0.00 4.53 2.80 3.56 2.48 2.14 .02 .62 .561

Mo 664 1989-99 0.42 4.35 2.81 3.42 2.89 2.34 .02 .64 .411

Mo 665 1989-99 3.90 7.48 5.81 6.35 5.83 5.35 .03 .52 .089

Mo 666 1989-99 3.66 6.75 5.42 5.93 5.46 5.00 .04 .65 .096

Mo 667 1989-99 0.20 6.06 2.59 3.75 2.50 1.50 .15 5.90 .000

Mo 668 1989-99 5.49 8.65 7.38 7.86 7.38 6.97 .03 .34 .125

Ground Water

MO 3

WATER LEVEL, IN FEET BELOW LAND SURFACE
12 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 8. Median concentrations of selected constituents in Ellison Park wells, Monroe County, N.Y., for 

period of record through 1996 and for 1997-99. (Locations are shown in fig. 5.)

15

0

5

0

15

5

10

0

3

1

2

0

8,000

2,000

4,000

6,000

0

3,000

1,000

2,000

Mo 2Mo 3

Mo 659Mo 663Mo 664Mo 665Mo 666Mo 667Mo 668

0

800

200

400

600

0

1,500

500

1,000

0

500

100

200

300

400

0

30

10

20

0

8,000

2,000

4,000

6,000

0

40,000

10,000

20,000

30,000

0

15,000

5,000

10,000

AMMONIA AMMONIA + ORGANIC

NITROGEN

TOTAL PHOSPHORUS

HARDNESS CALCIUM,

DISSOLVED

MAGNESIUM,

DISSOLVED

SODIUM, 

DISSOLVED

POTASSIUM,

DISSOLVED CHLORIDE,

DISSOLVED

SULFATE,

DISSOLVED

IRON TOTAL

DISSOLVED

SOLIDS

10

0

MEDIAN CONCENTRATION, IN MILLIGRAMS PER LITER

Period of record through 1996 1997-99

EXPLANATION

Mo 2

Mo 3

Mo 659

Mo 663

Mo 664

Mo 665

Mo 666

Mo 667

Mo 668

Mo 2

Mo 3

Mo 659

Mo 663

Mo 664

Mo 665

Mo 666

Mo 667

Mo 668
13

slightly lower at wells Mo 664, Mo 667, and 

Mo 668.

Median concentrations of most 

constituents in shallow wells showed 

significant differences from those in the deep 

well of a well pair. Generally, the lower 

concentrations were detected in the shallow 

wells. Well pair Mo 663-664, showed higher 

concentrations of all constituents at depth 

(well 664) except for turbidity, nitrite + 

nitrate, and hardness, which showed no 

difference in concentration with depth. The 

significantly higher concentrations of 

common ions in the deep well are attributed 

to the upwelling of mineralized water from 

the base of the Pinnacle Hills moraine. Well 

pair Mo 665-666 showed similar results, 

except that total dissolved solids showed no 

difference with depth. Well pair Mo 667-668 

showed no significant differences with depth 

for nitrite + nitrate, hardness or dissolved 

sulfate; the other constituents were about 

equally divided—six showed higher median 

concentrations in the shallow (Mo 667) well, 

and five constituents showed higher concentrations in 

the deep (Mo 668) well (table 5).

Temporal Trends

Constituent concentrations in water samples from 

Ellison Park wells were tested for trends through the 

Kendall slope estimator, a nonparametric test that does 

not account for seasonality in the data. The Kendall 

slope estimator incorporates the Mann-Kendall test to 

determine the statistical significance of the trend.

A total of 75 significant trends were detected 

among all wells and constituents; approximately twothirds (69 percent) of these trends were downward 

(table 6). The well with the highest number of 

constituents showing a significant trend was well Mo 3, 

where 11 of the 17 measured constituents showed a 

downward trend, and one (ammonia) showed an 

upward trend. Wells Mo 2 and Mo 663 showed 

significant trends in the concentration of 10 

constituents (eight downward at each well), whereas 

well Mo 666 showed significant trends in the 

concentration of only 4 constituents, 3 of which were 

downward. The constituent showing the greatest 

number of trends (8) among the wells was turbidity; the 

trend was upward at 4 wells and downward at 4 wells. 

The only well to show no trend in turbidity was Mo 2. 

The three constituents with the fewest number of trends 

(two each) were nitrite + nitrate, orthophosphate, and 

iron (dissolved oxygen was omitted because it was 

measured in only three wells). The common ions as a 

group showed the greatest number of trends among 

wells, most of which were downward. The constituent 

with the greatest number of significant trends (5) was 

ammonia; four of these were downward.

SURFACE WATER

Stage and streamflow data were collected at four 

sites in the Irondequoit Creek basin and at four sites in 

the Genesee River basin. Water-quality data were 

collected at four of the gaging stations in the 

Irondequoit Creek basin, at the Charlotte Pump station 

on the Genesee River (fig. 1) at a site on Northrup 

Creek in western Monroe County and at three other 

western Monroe County tributaries to the Genesee 

River—Honeoye Creek at Honeoye Falls, Oatka Creek 

at Garbutt, and Black Creek at Churchville. Streamflow 

and chemical-concentration data were used to test for 

trends in concentrations and to estimate annual loads of 

constituents transported by the streams.

Table 5. Statistically significant differences in median 

concentration of selected chemical constituents in paired 

wells, by depth, in Ellison Park, Monroe County, N.Y., 1997-99.

[D, mean for deep well is significantly higher than for shallow well; 

S, mean for shallow well is significantly higher than for deep well; 

nd, no significant difference. Locations are shown in fig. 5.]

Well Pair

Constituent or Property Mo 663 

Mo 664

Mo 665 

Mo 666

Mo 667 

Mo 668

Turbidity nd nd S

Specific conductance D D D

Ammonia, dissolved D D S

Ammonia + organic nitrogen, total D D S

Nitrite + Nitrate, total nd nd nd

Phosphorus, total D D S

Hardness nd nd nd

Magnesium, dissolved D D D

Sodium, dissolved D D D

Potassium, dissolved D D S

Chloride, dissolved D D D

Sulfate, dissolved D D nd

Iron, dissolved D D S

Total dissolved solids D D D

Surface Water
14 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Water Temperature

Temperature is one of the most important factors 

in water-quality control because it affects most 

physical properties of water as well as the rate of 

chemical reactions and the activity of all organisms in 

the aquatic environment. Some of the physical 

properties that are affected by temperature are density, 

specific heat, rate of vaporization, viscosity, and gas 

diffusibility; these properties in turn affect 

stratification, evaporation, velocity of settling 

particles, and dissolved oxygen saturation. Water 

temperature also affects the ionic strength and 

electrical conductivity of water, the solubility of 

constituents, and the growth and death rates of 

microorganisms, which are important to the biological 

processes of waste decomposition. Temperature 

changes also can affect higher aquatic organisms such 

as fish, although the effects are more complex and 

differ among species. 

Monroe County began collecting continuous 

records of water temperature at the four Irondequoit 

Creek basin surface-water-monitoring sites and at 

Northrup Creek in 1994. Temperatures reported herein 

(table 7) were recorded at a single point in the stream 

cross section and stream reach and, therefore, may not 

be representative of temperatures upstream or 

downstream of the monitoring site. Several factors 

affect the temperature of stream water as it moves 

down the channel; these include ground-water 

contribution, precipitation, the amount of solar 

radiation reaching the stream, and tributaries entering 

the stream.

In recent years, the New York State Department 

of Environmental Conservation (NYSDEC) has 

expressed concern as to whether discharges from 

stormflow-detention facilities to receiving streams 

may cause temperature increases that are detrimental 

to trout. Typically the temperature of water detained 

by a stormflow-detention basin increases during the 

summer through solar warming, and is often warmer 

than the water in receiving streams because it has 

previously been in contact with hot impervious 

surfaces. The NYSDEC threshold for discharges to 

trout streams are, that no discharge to trout streams 

will exceed 70o

 F (21.1oC), and no discharge from 

Table 6. Statistically significant (α = 0.05) trends in concentrations of selected ground-water constituents at Ellison Park wells, 

Monroe County, N.Y., period of record through 1999. 

[, downward trend;, upward trend; , no trend. Dashes indicate insufficient data for trend test. Locations are shown in fig. 5]

Constituent or Property

Mo 2

(1986-

99)

Mo 3

(1986-

99)

Mo 659

(1991-

99)

Mo 663

(1991-

99)

Mo 664

(1991-

99)

Mo 665

(1991-

99)

Mo 666

(1993-

99)

Mo 667

(1991-

99)

Mo 668

(1991-

99)

Total

no.

trends

UpwardDownward

Turbidity      8 4 4

Specific conductance     523

Oxygen, dissolved   -- --  -- -- -- -- 1 0 1

Ammonia, dissolved      514

Ammonia + organic nitrogen, total          4 0 4

Nitrite + nitrate, total    220

Phosphorus, total        4 2 2

Orthophosphate, dissolved   220

Hardness        4 2 2

Calcium, dissolved       523

Magnesium, dissolved        7 2 5

Sodium, dissolved       615

Potassium, dissolved          6 0 6

Chloride, dissolved      505

Sulfate, dissolved        5 2 3

Iron, dissolved     202

Total dissolved solids         4 1 3

Total number of trends 10 12810 6 9 4 8 8 75

Upward trends 2 1 7 2 1 6 1 3 0 23

Downward trends 8 11 1 8 5 3 3 5 8 52
15

Table 7. Monthly maximum, minimum, and mean water temperatures at four sites in the Irondequoit Creek basin sites and

Northrup Creek, Monroe County, N.Y., water years 1997-99.

[All values are in degrees Celsius; dashes indicate no data. Locations are shown in fig. 1.] 

Irondequoit Creek 

at Blossom Road

Allen Creek

near Rochester

East Branch 

Allen Creek

at Pittsford

Irondequoit Creek

at Railroad Mills

Northrup Creek

at North Greece

Month Max Min Mean Max Min Mean Max Min Mean Max Min Mean Max Min Mean

1997 Water Year

Oct 96 16.5 8.0 11.5 17.0 8.5 12.0 18.0 7.5 12.0 15.0 7.5 10.5 17.5 7.0 12.0

Nov 96 12.0 2.0 6.0 13.0 2.0 6.5 14.0 1.0 5.5 11.5 .5 5.0 12.0 .0 4.5

Dec 96 6.5 1.0 4.0 7.5 1.0 4.5 6.5 .5 3.5 6.0 1.0 4.0 6.0 .0 3.0

Jan 97 6.5 .0 1.5 6.5 .0 1.7 7.0 .0 1.5 7.0 .5 2.0 7.0 .0 .5

Feb 97 7.5 .0 2.5 8.5 .0 2.5 8.0 .0 1.5 8.0 .5 3.0 7.5 .0 1.0

Mar 97 10.5 .0 3.5 10.0 .0 4.0 9.5 .0 3.5 10.5 .5 4.0 11.0 .0 3.0

Apr 97 16.5 3.0 9.0 16.5 3.0 8.5 16.5 8.0 12.0 15.5 2.0 8.5 18.0 1.5 8.5

May 97 17.0 8.5 12.5 17.0 7.5 11.5 17.5 3.5 8.5 15.4 7.5 11.5 17.0 7.5 12.5

Jun 97 23.5 14.5 19.0 23.0 13.5 17.5 25.5 14.0 19.5 21.5 13.0 17.0 24.5 14.5 20.0

Jul 97 25.0 15.0 19.5 24.5 14.5 22.0 27.5 17.0 21.5 21.5 14.0 17.5 25.5 16.5 20.5

Aug 97 22.0 15.0 18.5 22.0 15.0 18.5 24.0 17.5 20.5 19.5 13.5 16.5 23.5 17.0 20.0

Sept 97 20.0 10.5 15.5 21.0 10.5 16.0 22.0 10.5 17.0 17.5 9.5 14.0 21.0 11.0 16.5

1998 Water Year

Oct 97 17.5 6.5 11.0 --- --- --- 18.5 6.0 11.0 16.0 6.5 10.5 18.5 5.5 11.0

Nov 97 11.0 1.5 5.5 --- --- --- 12.0 2.0 6.0 10.5 2.0 5.5 10.5 1.0 5.0

Dec 97 5.0 .5 3.0 --- --- --- 4.5 .5 3.0 5.0 .5 3.0 4.0 .0 2.0

Jan 98 8.0 .5 3.0 7.5 2.0 3.0 7.0 .5 2.4 8.0 .5 2.5 8.0 .0 2.0

Feb 98 6.0 .0 2.9 5.5 2.0 3.0 6.0 .5 2.5 6.0 .5 2.5 5.5 .0 2.0

Mar 98 16.5 .5 5.5 13.5 2.0 5.0 16.0 .5 4.5 16.5 1.0 5.5 17.5 .0 4.5

Apr 98 16.0 6.0 10.5 14.0 5.5 10.0 17.5 5.5 10.5 16.0 6.0 11.0 16.0 5.0 10.5

May 98 21.0 13.0 16.5 --- --- --- 22.5 12.0 16.5 20.0 12.0 16.0 21.5 12.5 16.5

Jun 98 24.0 12.5 18.0 --- --- --- 25.0 13.5 19.5 22.0 11.5 16.0 25.0 12.0 19.0

Jul 98 23.5 17.5 20.5 21.0 16.0 19.5 24.5 18.0 21.0 20.5 15.0 17.5 25.5 19.0 21.5

Aug 98 23.5 16.5 20.0 20.0 18.0 19.0 25.5 16.5 21.5 19.0 14.0 17.0 25.0 17.5 22.0

Sept 98 21.0 13.0 17.5 18.0 15.5 16.5 25.0 14.5 19.0 17.0 11.0 14.5 22.5 14.0 19.0

1999 Water Year

Oct 98 16.0 7.0 12.0 --- --- --- 17.5 7.0 12.5 14.0 6.5 10.5 17.5 7.0 12.5

Nov 98 11.0 6.0 7.5 --- --- --- 11.0 4.0 7.0 10.5 5.0 6.5 11.0 3.0 6.5

Dec 98 11.5 .0 4.5 --- --- --- 12.0 .0 4.0 11.0 .0 4.0 12.5 .0 3.5

Jan 99 1.5 .0 .5 --- --- --- 3.0 .0 .5 2.0 .0 .0 1.0 .0 .0

Feb 99 4.5 .0 2.0 5.5 .0 2.5 5.0 .0 1.5 4.0 .0 2.0 5.0 .0 1.0

Mar 99 11.5 .0 3.5 11.0 .0 3.0 11.0 .0 3.0 10.5 .0 2.5 12.0 .0 2.0

Apr 99 16.0 5.5 10.0 15.5 5.0 9.5 17.5 5.0 10.5 15.0 5.0 9.0 16.5 3.5 9.0

May 99 21.0 11.5 16.5 20.5 10.5 15.0 22.0 10.5 16.5 19.0 9.5 14.5 22.0 10.5 16.5

Jun 99 24.5 14.5 20.0 24.0 13.5 18.5 25.5 16.0 21.0 21.0 12.0 16.5 25.5 15.5 21.0

Jul 99 27.0 18.0 22.5 26.5 17.0 21.5 27.5 19.5 23.5 22.5 14.0 18.0 28.0 19.0 23.5

Aug 99 25.0 16.0 20.0 24.0 15.0 19.5 25.5 17.5 21.0 20.5 13.0 16.5 25.0 17.0 21.0

Sept 99 --- --- --- 23.0 12.0 17.5 24.0 12.0 18.5 18.0 10.5 14.5 24.5 13.5 19.0

Surface Water
16 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

June through September will increase stream 

temperature more than 2o

 F (1.1oC) over its predischarge temperature.

The optimum temperature range for trout (10o

 to 

22o

C) (Bidgood and Berst, 1969) is the range over 

which feeding occurs and that produces no external 

signs of abnormal behavior. The optimum temperature 

range for most species generally overlaps the upper 

and lower critical ranges. The critical temperature 

ranges (19o

 to 30o and 0o to 10oC) are the ranges over 

which a noticeable disturbance in the normal behavior 

of a fish may occur. These critical temperature ranges 

vary, depending on the species of fish.

Maximum daily water temperatures during 1997-

99 exceeded the 22.0o C limit on many days during the 

summer months at all sites (table 7, fig. 9). Daily mean 

temperatures for those days generally were lower than 

22.0o

 C, however, and those at Railroad Mills did not 

exceed that limit (fig. 10). The minimum daily 

temperatures did not exceeded 22o

C at any of the sites.

Temporal Trends in Streamflow

Variability in streamflow reflects climatic 

conditions and affects many water-quality properties; 

it also can produce a significant bias in the trends of 

constituent concentrations. Concentration-todischarge relations and trends in streamflow form an 

important basis for interpretation of trends in water 

quality. For example, increasing runoff (overland flow 

from rainfall) causes washoff of chemical constituents 

to streams and thereby increases the concentrations of 

suspended constituents from nonpoint sources; at the 

same time it can decrease the concentration of some 

dissolved constituents through dilution. Therefore, any 

observed trend in constituent concentration could be at 

least partly due to a concurrent trend in streamflow. 

Monthly mean streamflow data from the four 

Irondequoit Creek basin sites and Northrup Creek 

(table 8) were tested for trends with the Seasonal 

Kendall Trend Test. Trends in streamflow were 

considered statistically significant if the level of 

significance (p value) was less than or equal to 0.05. 

Only those periods of streamflow with accompanying 

water-quality data were tested for trends. 

Two sites showed significant trends in streamflow 

(table 8). Allen Creek in the Irondequoit Creek basin 

had a downward trend of 1.25 percent per year in 

monthly mean streamflow for 1984-99, which is 

consistent with the downward trend of 2.26 percent 

per year noted for the previous report period, 1984-96. 

Northrup Creek in western Monroe County showed an 

upward trend of 4.28 percent per year for 1989-99, 

which contrasts with the lack of a discernible trend for 

the previous report period, 1989-96. The upward trend 

for this period is likely the result of increased runoff 

from precipitation during 1997-99 and increased 

diversion from the Erie (Barge) canal during the 

navigation season. Trends observed in the four 

Irondequoit Creek sites and Northrup Creek are 

summarized in the following paragraphs.

Irondequoit Creek at Blossom Road

The Irondequoit Creek basin has two sites with at 

least 19 years of continuous streamflow 

record—Irondequoit Creek at Blossom Road (1981-

99, 19 years), and Allen Creek near Rochester (1960-

99, 40 years). The Blossom Road record for the 1997-

99 water years, showed 2 months (January and July) in 

which the 3-year mean monthly flows were above 

normal (fig. 12). The normal range is defined as 

between the 25th percentile (flows exceeded 75 

percent of the time) and the 75th percentile (flows 

exceeded 25 percent of the time). The high January 

mean was the result of a rainfall/snowmelt event on 

January 8, 1998, that produced the peak of record at 

this site (3,300 ft3

/s). None of the 3-year mean 

monthly flows for 1997-99 were below normal. 

Monthly mean flow for water year 1997 exceeded 

normal for October, November, and December and, in 

addition, exceeded the period-of-record median (50th 

percentile) for March and September (fig. 11). Flows 

were slightly below normal for July and August and 

also below the median for April. Flows for water year 

1998 were above normal for January, February, 

March, and July, and slightly above normal for 

August. Flows for the remaining months were within 

the normal range except for April and May, when they 

were slightly below normal. Flows for water year 1999 

were slightly above normal for March and below 

normal for November, December, June, and July. 

Annual mean flows for the period of record are shown 

in figure 13. 

Allen Creek Near Rochester

The Allen Creek drainage basin is primarily 

moderate- to high-density residential land with some 

commercial areas and, therefore, is not representative 

of the rest of the Irondequoit Creek basin. Mean 
17

Oct96

Dec96

Feb97

Apr97

Jun97

Aug97

Oct97

Dec97

Feb98

Apr98

Jun98

Aug98

Oct98

Dec98

Feb99

Apr99

Jun99

Aug99

0

30

10

20

EXPLANATION

MEAN MONTHLY TEMPERATURE

0

30

10

20

0

30

10

20

0

30

10

20

MONTHLY TEMPERATURE RANGE

0

30

10

20

IRONDEQUOIT CREEK AT

BLOSSOM ROAD

ALLEN CREEK NEAR

ROCHESTER

EAST BRANCH

ALLEN CREEK

AT PITTSFORD

IRONDEQUOIT CREEK

AT RAILROAD MILLS

NORTHRUP CREEK AT

NORTH GREECE

WATER TEMPERATURE, IN DEGREES CELSIUS

Figure 9. Monthly watertemperature range and mean 

monthly water temperature at four 

sites in the Irondequoit Creek basin 

and Northrup Creek, Monroe 

County, N.Y., water years 1997-99. 

(Locations are shown in fig. 1.)

Surface Water
18 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 10. Daily mean water temperatures at four sites in the Irondequoit Creek basin and 

Northrup Creek, Monroe County, N.Y., water years 1997-99. (Locations are shown in fig. 1.)

0

30

10

20

0

30

10

20

0

30

10

20

O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

1997 1998 1999

0

30

10

20

0

30

10

20

IRONDEQUOIT CREEK AT BLOSSOM ROAD

ALLEN CREEK

EAST BRANCH ALLEN CREEK

IRONDEQUOIT CREEK AT RAILROAD MILLS

NORTHRUP CREEK AT NORTH GREECE

WATER TEMPERATURE, IN DEGREES CELSIUS

Maximum optimum temperature range for trout

 NEAR ROCHESTER

 AT PITTSFORD
19

monthly flows of Allen Creek for water years 1997-99 

were above the normal range for January and July and 

below the normal range for April and May (fig. 12). As 

at Blossom Road, the high January mean flow was in 

response to the high flow event of January 8, 1998, 

which at this site did not produce a record peak. 

Monthly mean flows for water year 1997 were slightly 

above normal for October and December and below 

normal for April through August (fig. 11). Monthly 

mean flows at Allen Creek showed a wide variation for 

the 1998 water year—those for January and July were 

well above normal whereas those for April and May 

were well below normal. The wider variation in flows 

at Allen Creek is probably a result of the urban 

character of drainage area. Flows for the 1999 water 

year also varied widely—those for November, 

December, and April through August were below 

normal; only the mean flow for January was above 

normal. Annual mean flows at Allen Creek were above 

the long-term average for a sustained period (1968-79) 

in 1998 and below in 1997 and 1999 (fig. 14).

Black Creek at Churchville

Black Creek at Churchville (fig. 1) has a 54-year 

record, which was used to relate long-term flow 

conditions in western Monroe County (west of the 

Genesee River) to those in Northrup Creek during 

1997-99. As at Blossom Road and Allen Creek, many 

of the mean monthly flows for the 1997-99 water years 

were outside the normal range (fig. 12). The 3-year 

mean monthly flow exceeded normal for October, 

November, January, and July, and was below normal 

for April. During the 1997 water year, monthly mean 

flow exceeded normal for October through December, 

February, and September, and was below normal only 

for April (fig. 11). Mean monthly flows for 1998 were 

above normal for all months except March, May and 

June, during which they were in the normal range, and 

April, in which they were slightly below normal. In 

contrast, none of the mean monthly flows for the 1999 

water year were above normal, and those for 

December and for April through July were below 

normal. Annual mean flows at Black Creek also were 

above the long-term average for a sustained period 

(1968-79) in 1997-98 and below in 1999 

(fig. 14).

Chemical Concentrations

Streamflow was measured at all sites where water 

samples were collected, except the Genesee River at 

the Charlotte Pump station. Streamflow values for the 

Charlotte Pump station site were obtained from 

records for the Genesee River at Rochester 

(04232000), about 6 mi upstream. Water samples were 

collected hourly at each of the streamflow-gaging 

stations by automatic sampler. Samples collected at 

the upstream sites in the Irondequoit Creek basin and 

Northrup Creek, are combined into 2- to 4- day 

composite samples each quarter to produce a sample 

representing baseflow conditions and are composited 

for shorter periods of time over high flow events to 

produce approximately two high flow samples per 

month. Baseflow samples from all other sites are 

combined into 2- to 4- day composite samples to 

produce 1 to 2 baseflow samples per week and those 

collected during high flows are combined into 5 to 6 

flow weighted composite samples that span the 

duration of the high flow event. Samples were 

analyzed for physical properties and for 

concentrations of nutrient species and common ions. 

For purposes of statistical evaluation, these composite 

samples are treated as discrete samples. Median 

constituent concentrations are shown in table 9.

Table 8. Statistical summary and results of trend tests for streamflow at Northrup Creek and four sites in the Irondequoit 

Creek basin, Monroe County, N.Y., period of record through 1999.

[Mean, median, 25th, 75th percentiles, and trend units are in cubic feet per second. p, significance of trend. Bold type indicates trend is 

statistically significant at α = 0.05.] 

Period of 

trend test

Descriptive statistics Trend results

Site

no. of 

samples Mean

25th

percentile Median

75th

percentile

no. of

seasons

no. of 

samples

Units per 

year

Percent 

per year p

Northrup Creek 1989-99 120 13.7 5.12 10.7 21.6 12 120 0.587 4.28 0.021

Railroad Mills 1992-99 96 39.2 20.6 31.0 51.0 12 96 -.287 -.732 .474

East Branch Allen 1991-99 108 8.89 3.86 6.38 12.5 12 108 .000 .00 1.000

Allen Creek 1984-99 192 29.2 14.9 22.2 39.7 12 192 -.364 -1.25 .020

Blossom Road. 1984-99 192 136 71.2 104 185 12 192 -.448 -.329 .558

Surface Water
20 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 11. Monthly mean flow of three streams in Monroe County, N.Y., water years 1997, 1998, and 

1999, in relation to normal range (flows between the 25th and 75th percentile) for period of record: A. 

Irondequoit Creek at Blossom Road. B. Allen Creek near Rochester. C. Black Creek at Churchville. 

(Location is shown in fig. 1.)

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

5

100

7

10

30

50

70

B. Allen Creek near Rochester

10

1,000

30

50

70

100

300

500

700

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

A. Irondequoit Creek at Blossom Road

1

1,000

3

5

7

10

30

50

70

100

300

500

700

STREAMFLOW, IN CUBIC FEET PER SECOND

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

STREAMFLOW, IN CUBIC FEET PER SECOND STREAMFLOW, IN CUBIC FEET PER SECOND

C. Black Creek at Churchville

1997 water year

1998 water year

1999 water year

75th percentile (exceeded 25 percent of time)

25th percentile (exceeded 75 percent of time)

{ 50th percentile (exceeded 50 percent of time)

75th percentile

25th percentile

50th percentile

50th percentile

50th percentile

Normal

range
21

Figure 12. Mean monthly flows of three streams in Monroe County, N.Y., for period of record and 

three-year period, water years 1997-99, in relation to normal range (flows between the 25th and 

75th percentile) for period of record: A. Irondequoit Creek at Blossom Road. B. Allen Creek near 

Rochester. C. Black Creek at Churchville. (Location is shown in fig. 1.) 

B. Allen Creek near Rochester

5

100

7

10

30

50

70

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

10

1,000

30

50

70

100

300

500

700

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

75th percentile (exceeded 25 percent of time)

25th percentile (exceeded 75 percent of time)

50th percentile (exceeded 50 percent of time)

1981-99 monthly mean

1997-99 monthly mean

{

A. Irondequoit Creek at Blossom Road

STREAMFLOW, IN CUBIC FEET PER SECOND

STREAMFLOW, IN CUBIC FEET PER SECOND

1

1,000

3

5

7

10

30

50

70

100

300

500

700

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

STREAMFLOW, IN CUBIC FEET PER SECOND

C. Black Creek at Churchville

75th percentile

50th percentile

50th percentile

25th percentile

50th percentile

1961 monthly mean

1997-99 monthly mean

1946-99 monthly mean

1997-99 monthly mean

Surface Water

Normal

range
22 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 13. Annual mean flow for Irondequoit Creek at Blossom Road, Rochester, N.Y., and mean 

annual flow for period of record. (Only complete water years are shown. Location is shown in fig. 1) 

Figure 14. Annual mean flows for Allen Creek near Rochester and Black Creek at Churchville 

with mean annual flow for period of record. (Only complete water years are shown. Location is 

shown in fig. 1.) 

194619471948194919501951195219531954195519561957195819591960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999

40

220

60

80

100

120

140

160

180

200

EXPLANATION

Annual mean flow

Mean annual flow

Black Creek at Churchville

STREAMFLOW, IN CUBIC FEET PER SECOND

194619471948194919501951195219531954195519561957195819591960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999

10

60

20

30

40

50

Allen Creek near Rochester

EXPLANATION

Annual mean flow

Mean annual flow

STREAMFLOW, 

IN CUBIC FEET PER SECOND

1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

50

200

100

150
23

Spatial Variability

Chemical variability among streams is generally 

a result of the land use in the basin. For example, 

median concentrations of dissolved chloride are 

higher at the downstream sites that drain urbanized 

areas than at the upstream sites, which drain more 

agricultural land. 

Erie (Barge) Canal Diversions

Water from the Erie (Barge) canal is used to 

supplement flow in some streams north of the canal 

during the canal navigation season, from about April 

15 to about November 15. Water diverted from the 

canal is used to maintain minimum flows in the 

streams during low-flow periods for dilution of 

sewage-treatment-plant discharges, for irrigation, and 

to help maintain canal pool elevation. The Monroe 

County Environmental Health Laboratory (MCEHL) 

has been sampling these diversions (water is diverted 

by siphons) at Allen Creek, East Branch Allen Creek, 

the Cartersville waste channel, which diverts water 

from the canal to Irondequoit Creek, and at the 

Fairport waste channel, which diverts water from the 

canal to Irondequoit Creek through Thomas Creek, 

since 1986 (fig. 2). Samples are collected at Allen 

Creek and East Branch Allen Creek, immediately 

upstream of the siphon, at the siphon, and immediately 

downstream of the siphon. The East Branch Allen 

Creek canal siphon is about 1.1 mi upstream of the 

monitoring site on East Branch Allen Creek, and the 

Allen Creek siphon is about 4.6 mi upstream of the 

monitoring site on Allen Creek (fig. 2). Cartersville 

and Fairport samples are collected directly from the 

waste channels. Median concentrations of constituents 

at the Allen Creek and East Branch Allen Creek sites 

for the period of record are plotted in figure 15.

Median concentrations of turbidity, total 

suspended solids, volatile suspended solids, nitrite + 

nitrate, and sulfate were significantly higher in 

samples from the canal siphon at East Branch Allen 

Creek than in samples collected immediately upstream 

of the siphon (table 10). This resulted in significantly 

higher median concentration of these constituents just 

downstream of the siphon. Concentrations of ammonia 

+ organic nitrogen, orthophosphate, and chloride were 

lower at the siphon than at the upstream site, this 

resulted in lower concentrations through dilution of 

these constituents at the downstream site than at the 

upstream site. The only constituent to show a 

statistically significant lower concentration at the 

siphon and, consequently, at the downstream site than 

at the upstream site was chloride. The median 

concentration of orthophosphate was significantly 

lower at the siphon than upstream, which resulted in a 

lower (although not significant) median concentration 

Table 9. Median concentrations of selected constituents at four sites in the Irondequoit Creek basin and four western sites in 

Monroe County, N.Y., water years 1997-99.

[Units are milligrams per liter unless otherwise noted. NTU, nephelometric turbidity units. Locations are shown in fig. 1.]

Site

Turbidity 

(NTU)

Total suspended 

solids

Volatile 

suspended 

solids

Ammonia 

as N, 

dissolved

Ammonia 

+ organic 

nitrogen

as N, 

total

Nitrite + 

nitrate as 

N, total

 Phosphorus 

as P, 

total

Orthophosphate

as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Irondequoit Creek basin sites

Irondequoit Creek at 

Railroad Mills 17 136 17 0.01 0.34 1.1 0.075 0.008 74 152

East Branch Allen 

Creek at Pittsford 16 108 15 .02 .51 .71 .095 .020 108 79

Allen Creek near 

Rochester 11 139 19 .02 .49 .88 .085 .018 158 58

Irondequoit Creek at 

Blossom Road 11 96 14 .01 .45 1.0 .075 .012 123 133

Western Monroe County sites

Northrup Creek at 

North Greece 13 114 17 .06 .80 1.3 .15 .050 90 49

Honeoye Creek at

Honeoye Falls 6.6 86 10 .01 .34 .08 .045 .010 30 22

Oatka Creek at 

Garbutt 3.0 7 5 .02 .35 1.4 .03 .007 47 279

Black Creek at

Churchville 3.6 78 24 .03 .60 .80 .06 .12 53 253

Surface Water
24 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 15. Median concentrations of selected constituents at Erie 

(Barge) Canal diversions at Allen Creek and East Branch Allen 

Creek, Monroe County, N.Y., period of record through 1999. (Data in 

table 10. Locations are shown in fig. 2.) 

4

16

6

8

10

12

14

0

30

10

20

2

6

3

4

5

0.02

0.08

0.04

0.06

0.055

0.075

0.060

0.065

0.070

East Branch Allen Creek 50

90

60

70

80

EXPLANATION

Concentration upstream of canal siphon

Concentration of canal water at siphon

Concentration downstream of siphon

0.4

1.0

0.6

0.8

0

0.8

0.2

0.4

0.6

East Branch Allen Creek 0.005

0.025

0.010

0.015

0.020

East Branch Allen Creek 50

200

100

150

TURBIDITY TOTAL SUSPENDED

 SOLIDS

VOLATILE SUSPENDED 

SOLIDS

AMMONIA AMMONIA + ORGANIC

NITROGEN

NITRITE + NITRATE

TOTAL PHOSPHORUS ORTHOPHOSPHATE CHLORIDE,

DISSOLVED

SULFATE,

DISSOLVED

CONCENTRATION, IN MILLIGRAMS PER LITER
25

Table 10. Median concentrations of selected constituents at Erie (Barge) Canal diversions on East Branch Allen Creek, 

Allen Creek, and Irondequoit Creek, Monroe County, N.Y., period of record through 1999.

[Units are milligrams per liter unless otherwise noted. NTU, nephelometric turbidity units. Locations are shown in fig. 2.]

Site

Turbidity 

(NTU)

Total suspended 

solids

Volatile 

suspended 

solids

Ammonia 

as N, 

dissolved

Ammonia 

+ organic 

nitrogen

as N, 

total

Nitrite + 

nitrate as 

N, total

 Phosphorus 

as P,

total

Orthophosphate

as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

East Branch Allen Creek canal sites

above siphon 6.15 9.0 3.0 0.030 0.68 0.30 0.065 0.024 101 60

at siphon 14.0 26.0 4.0 .055 .60 .55 .065 .015 67 82

below siphon 13.0 22.0 5.0 .050 .68 .50 .070 .021 82 78

Allen Creek canal sites

above siphon 7.05 10.0 4.0 .040 .90 .20 .060 .008 184 51

at siphon 15.0 27.0 4.0 .070 .59 .60 .070 .018 64 75

below siphon 13.0 20.5 4.0 .060 .77 .50 .065 .014 99 69

Irondequoit Creek canal sites

Cartersville waste 13.0 21.5 4.0 .038 .51 .70 .066 .024 64 82

Fairport waste 5.4 10.0 3.0 .050 .56 .50 .065 .019 72 87

downstream. Similar results were noted at the canal 

diversion at Allen Creek. Here the median 

concentrations of ammonia were significantly higher 

at the siphon and the downstream site than at the 

upstream site, whereas concentrations of ammonia + 

organic nitrogen were significantly lower at the siphon 

and downstream site than at the upstream site. 

Instantaneous nutrient loads—obtained by 

multiplying concentration by the corresponding flow 

and by a conversion factor that converts milligrams 

per liter and cubic feet per second to pounds per 

day—were calculated for the point upstream of the 

canal siphon, the canal siphon, and the point 

downstream of the siphon at the East Branch Allen 

Creek and Allen Creek sites (table 11). Even though 

median concentrations (fig. 15) of some nutrients such 

as ammonia + organic nitrogen, total phosphorus and 

orthophosphate in discharge from the canal at East 

Branch Allen Creek were the same as, or lower than, 

in water just upstream of the siphon, median loads of 

these constituents at points downstream of the siphon 

were greater than those upstream (fig. 16) because 

water from the canal is the main component of the 

flow in the stream at that point. Similar results were 

found at the canal sampling points on Allen Creek. 

Thus, the diversion from the canal is the main 

contributor of nutrients to the reaches of East Branch 

Allen Creek and Allen Creek below the siphons for 

periods of base flow during the navigation season. 

Median concentrations of constituents at the 

Fairport waste channel and the Cartersville waste 

channel are included in table 10. Unlike East Branch 

Table 11. Median values of instantaneous flow and nutrient loads at Erie (Barge) 

Canal diversions on East Branch Allen Creek, and Allen Creek, Monroe County, 

N.Y. period of record through 1999.

[Units are pounds per day unless otherwise noted. Locations are shown in fig. 2.]

Site

Discharge

(cubic feet 

per second)

Ammonia 

as N, 

dissolved

Ammonia 

+ organic 

nitrogen

as N, 

total

Nitrite + 

nitrate as 

N, total

 Phosphorus 

as P, total

Orthophosphate

as P, 

dissolved

East Branch Allen Creek canal sites

above siphon 0.62 0.081 2.16 1.78 0.24 0.052

at siphon 2.3 .675 5.03 6.21 .76 .286

below siphon 2.6 .562 8.37 8.75 1.08 .322

Allen Creek canal sites

above siphon 1.15 .186 3.72 1.3 .39 .043

at siphon 1.75 .383 3.98 4.86 .59 .134

below siphon 2.85 .697 11.2 6.21 1.07 .198

Surface Water
26 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Figure 16. Median values of instantaneous flow and nutrient 

loads at Erie (Barge) Canal diversions at East Branch Allen Creek 

and Allen Creek, Monroe County, N.Y., period of record through 

1999. (Data in table 11. Locations are shown in fig. 2.) 

0.5

3.0

1.0

1.5

2.0

2.5

0

0.8

0.2

0.4

0.6

0

12

2

4

6

8

10

0

10

2

4

6

8

0.2

1.4

0.4

0.6

0.8

1.0

1.2

0

0.4

0.1

0.2

0.3

EXPLANATION

Constituent load upstream of canal siphon

Constituent load at canal siphon

Constituent load below canal siphon

East Branch Allen Creek East Branch Allen Creek East Branch Allen Creek

FLOW AMMONIA AMMONIA + ORGANIC

NITROGEN

NITRITE + NITRATE TOTAL PHOSPHORUS ORTHOPHOSPHATE

LOAD, IN POUNDS

LOAD, IN POUNDS

FLOW, IN CUBIC FEET PER SECOND

Allen Creek and Allen Creek, the canal diversions 

from those sites to Irondequoit Creek have no 

sampling sites immediately upstream and downstream 

of the diversions by which to assess the relative impact 

of canal water on constituent concentrations in 

Irondequoit Creek.

Differences in median and range of concentration 

of selected constituents from the Irondequoit basin 

sites and the sites west of the Genesee River were 

examined through boxplots (fig. 17) and Tukey’s MCT 

(multiple comparison test) on ranks of the 

concentration data to identify significant (α = 0.05) 

differences among sites in mean concentration. The 

results are summarized in table 12. Differences in 

median concentration of constituents among sites for 

the period of record through 1996 and for 1997-99 are 

illustrated in figure 18.

Irondequoit Creek Basin Sites

Differences in median concentration of some 

constituents were noted among Irondequoit Creek 

subbasins as well as between time periods. The 

median is often used as a measure of central tendency 

rather than the mean because it is not influenced by 

extreme values, as the mean is.

Nutrients: Median concentrations of nutrients 

during 1997-99 were fairly uniform among all sites 

(table 9). Nitrite + nitrate showed the greatest range in 

concentration—from 0.71 mg/L at East Branch Allen 

Creek to 1.1 mg/L at Irondequoit Creek at Railroad 

Mills, which had the lowest concentration (0.34 mg/L) 

of ammonia + organic nitrogen. The highest median 

concentration of ammonia + organic nitrogen 

(0.51 mg/L) was at East Branch Allen Creek. Median 

concentrations of total phosphorus and orthophosphate 

differed little among sites (0.075 to 0.095 mg/L and 

0.008 to 0.020 mg/L, respectively). The constituents 
27

Figure 17. Ranges in concentration of selected constituents in samples from four Irondequoit Creek basin sites, 

Northrup Creek, and three other sites in western Monroe County, N.Y., water years 1997-99. (Locations are shown in 

fig. 1) 

1

10,000

2

5

10

20

50

100

200

500

1,000

2,000

5,000

0.01

10

0.02

0.05

0.1

0.2

0.5

1

2

5

10

10,000

20

50

100

200

500

1,000

2,000

5,000

0.001

10

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

1,000

2

5

10

20

50

100

200

500

0.001

1

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

0.001

10

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

TOTAL

SUSPENDED 

SOLIDS

AMMONIA AMMONIA + ORGANIC

NITROGEN

NITRITE + NITRATE TOTAL

PHOSPHORUS

ORTHOPHOSPHATE

CHLORIDE,

DISSOLVED

SULFATE, DISSOLVED

NC HC OC BC RM EB AC BR

NC Northrup Creek at North Greece

HC Honeoye Creek at Honeoye Falls

OC Oatka Creek at Garbutt

BC Black Creek at Churchville

RM Irondequoit Creek at Railroad Mills

EB East Branch Allen Creek at Pittsford

AC Allen Creek near Rochester

BR Irondequoit Creek at Blossom Road

25th percentile

Median

75th percentile

interquartile range

Values within 1.5 times 

the

interquartile range 

Outlier data value more than 

3 times the

outside the quartile

interquartile range outside the quartile

and more than 1.5 times 

Outlier data value less than or equal to 3 the

EXPLANATION

NC HC OC BC RM EB AC BR NC HC OC BC RM EB AC BR

1.0

CONCENTRATION, IN MILLIGRAMS PER LITER

Surface Water

.

NC HC OC BC RM EB AC BR NC HC OC BC RM EB AC BR

NC HC OC BC RM EB AC BR NC HC OC BC RM EB AC BR

NC HC OC BC RM EB AC BR NC HC OC BC RM EB AC BR NC HC OC BC RM EB AC BR
28 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Table 12. Results of Tukey’s Multiple Comparison Test (MCT) showing statistically significant (α = 0.05) differences in 

mean concentrations of selected constituents among Irondequoit Creek basin sites and Northrup Creek, Monroe 

County, N.Y., water years 1997-99.

[H indicates value for boldface site is significantly higher; L indicates value for boldface site is significantly lower; 

ND; no significant difference. Locations are shown in fig. 1.] 

Site Turbidity 

Total

suspended 

solids

Volatile 

suspended 

solids

Ammonia, 

dissolved

Ammonia 

+ organic 

nitrogen,

total

Nitrite + 

nitrate,

total

Phosphorus,

total

Orthophosphate,

dissolved

Chloride, 

dissolved

Sulfate,

dissolved

Irondequoit Creek at Blossom Road in relation to:

Irondequoit Creek at Railroad Mills L ND ND ND ND ND ND H H L

East Branch Allen Creek at Pittsford L ND ND L ND ND L H H H

Allen Creek near Rochester ND ND ND ND ND H ND L L H

Northrup Creek at North Greece ND ND ND L L L L L H H

Black Creek at Churchville H ND ND L L H H ND H L

Oatka Creek at Garbutt HH H L H H HH H H

Honeoye Creek at Honeoye Falls H ND ND ND H H H ND H H

Irondequoit Creek at Railroad Mills in relation to:

East Branch Allen Creek at Pittsford ND ND ND L L ND L L L H

Allen Creek near Rochester H ND ND L ND ND ND L L H

Northrup Creek at North Greece ND ND ND L L L L L ND H

Black Creek at Churchville H ND ND L L H ND L H H

Oatka Creek at Garbutt H H H L ND ND H ND H H

Honeoye Creek at Honeoye Falls H ND ND ND ND H H ND H H

Northrup Creek at North Greece in relation to:

East Branch Allen Creek at Pittsford ND ND ND H H H H H L L

Allen Creek near Rochester ND ND ND H H H H H L ND

Black Creek at Churchville H ND ND H H ND H H H L

Oatka Creek at Garbutt HH H H H H HH H L

Honeoye Creek at Honeoye Falls H ND ND H H H H H H H

East Branch Allen Creek at Pittsford in relation to:

Allen Creek near Rochester H ND ND H ND ND ND ND L H

Black Creek at Churchville H ND ND ND L ND H H H L

Oatka Creek at Garbutt HH H H H L HH H L

Honeoye Creek at Honeoye Falls H ND ND H H H H H H H

Allen Creek near Rochester in relation to:

Black Creek at Churchville H ND ND L L ND H H H L

Oatka Creek at Garbutt H H H ND H L H H H L

Honeoye Creek at Honeoye Falls H ND ND L H H H H H H

Black Creek at Churchville in relation to:

Oatka Creek at Garbutt ND ND H H H L H H L H

Honeoye Creek at Honeoye Falls L ND ND H H H H ND H H

Oatka Creek at Garbutt in relation to:

Honeoye Creek at Honeoye Falls L L L H ND H HH H H

Total significant differences 21 6 7 22 20 19 23 22 27 27

with the greatest number of significant differences 

among sites were phosphorus, ammonia, and 

orthophosphate, with 22 or 23 differences each 

(table 12).

Chloride and Sulfate: The highest median 

concentrations of chloride for 1997-99 as well as the 

previous periods have occurred at Allen Creek, where 

the median concentration for 1997-99 was 158 mg/L. 

The highest median concentration of sulfate (152 mg/L) 

for 1997-99 was at Irondequoit Creek at Railroad Mills 

which also has had the highest median concentrations 

in the past. The differences in chloride concentration 

among sites is related to the amount and rate of roadsalt application; thus, sites that represent the most 
29

Figure 18. Median concentrations of selected constituents in samples from four Irondequoit Creek basin sites and Northrup 

Creek, Monroe County, N.Y., for the period of record through 1996 and 1997-99. (Locations are shown in fig. 1.) 

EXPLANATION

Median concentration for period 

RM Irondequoit Creek at Railroad Mills

DISCHARGE, IN CUBICFEET PER SECOND

CONCENTRATION, IN MILLIGRAMS PER LITER

150

0

50

100

12

22

14

16

18

20

0.6

1.6

0.8

1.0

1.2

1.4

60

180

80

100

120

140

160

8

20

10

12

14

16

18

0

0.08

0.02

0.04

0.06

0

0.4

0.1

0.2

0.3

0

200

50

100

150

80

160

100

120

140

0

1.5

0.5

1.0

0

0.20

0.05

0.10

0.15

DISCHARGE TURBIDITY TOTAL SUSPENDED

SOLIDS

VOLATILE SUSPENDED 

SOLIDS

AMMONIA AMMONIA + ORGANIC

NITROGEN

NITRITE + NITRATE TOTAL PHOSPHORUS ORTHOPHOSPHATE

CHLORIDE,

DISSOLVED SULFATE,

DISSOLVED

RM BR EB AC NC RM BR EB AC NC

RM BR EB AC NC

CONCENTRATION, IN

MILLIGRAMS PER LITER

Surface Water

of record through 1996 

Median concentration 1997-99

NC Northrup Creek at North Greece

AC Allen Creek near Rochester

EB East Branch Allen Creek at Pittsford

BR Irondequoit Creek at Blossom Road 
30 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

urbanized subbasins (those with the highest road 

density) show the highest median concentrations. 

The high concentrations of sulfate at the Irondequoit 

sites result from the dissolution of sulfate from the local 

glacial deposits and from the shale bedrock that 

underlies much of the area (Young, 1993). Median 

concentrations of chloride and sulfate showed 

significant differences among most of the sites (table 

12). Median concentrations of chloride for all 

Irondequoit basin sites were higher in the 1997-99 than 

in the previous period of record, whereas median 

sulfate concentrations for 1997-99 at all sites were 

lower (fig. 18).

Suspended Solids: The median concentrations for 

1997-99 of total suspended solids were highest at 

Allen Creek and Railroad Mills (139 and 136 mg/L, 

respectively), and were lowest at Blossom Road. 

Median concentrations of volatile (the organic fraction 

of suspended solids) suspended solids were fairly 

uniform throughout the Irondequoit basin sites, and 

ranged from 14 mg/L at Blossom Road to 19 mg/L at 

Allen Creek. The lower concentrations at the 

downstream sites result from the settling out of these 

constituents as stream gradients decrease. The 

30-percent decrease in median concentrations of total 

and volatile suspended solids at Blossom Road may 

result partly because of the stabilization of a length of 

stream bank along Irondequoit Creek in Linear Park 

(fig. 2.).

Western Monroe County Sites

Median concentrations of turbidity, total 

suspended solids, and volatile suspended solids at the 

sites representing primarily agricultural subbasins in 

western Monroe County were lower than at sites in the 

Irondequoit Creek basin. Median concentrations of 

nutrients were similar to those in the Irondequoit 

Creek basin, whereas median concentrations of 

chloride were lower and those for sulfate were higher. 

Median concentrations of nutrients at Northrup Creek 

continued to be higher than those found in the 

Irondequoit Creek basin, but, because of the improved 

treatment of phosphorus at the sewage-treatment 

plant, concentrations of phosphorus, while still higher 

than at the Irondequoit basin sites, were not as much 

higher. Median concentrations reported for the three 

streams tributary to the Genesee River—Honeoye 

Creek at Honeoye Falls, Oatka Creek at Garbutt, and 

Black Creek at Churchville—do not represent the 

entire 1997-99 period and therefore, cannot be 

reliably compared with median concentrations for the 

other sites.

Temporal variability

A statistical test, ANOVA (analysis of variance) 

and Tukey’s Multiple Comparison Test were applied to 

ranked concentration data to detect statistically 

significant (α = 0.05) differences in median 

concentrations between the period of record prior to 

1997 at each site and those for the 1997-99 period 

(table 13). 

Table 13. Statistically significant differences between mean concentrations of selected constituents for 

period of record through 1996 and those for 1997-99 at Irondequoit Creek basin sites and Northrup 

Creek, Monroe County, N.Y.

[L, mean for 1997-99 is significantly lower than that for pre-1997 period; H, mean value for 1997-99 is significantly 

higher than that for pre-1997 period; ND, no significant difference. Locations are shown in fig. 1.] 

Constituent or property

Blossom 

Road

Allen

Creek

East Branch 

Allen Creek

Railroad 

Mills

Northrup

Creek

Discharge -- -- ND ND H

Turbidity L L ND ND ND

Suspended solids L ND ND ND ND

Volatile suspended solids L ND ND ND ND

Ammonia, dissolved L L ND ND H

Ammonia + organic nitrogen, total LLLLL

Nitrite + nitrate, total ND L L ND L

Phosphorus, total L L ND ND L

Orthophosphate, dissolved H ND ND H H

Chloride, dissolved H ND ND H ND

Sulfate, dissolved L L ND L L

Total significant differences 96246
31

The sites with the fewest number of significant 

differences between the two periods were the two 

upstream sites in the Irondequoit Creek basin—East 

Branch Allen Creek and Irondequoit Creek at Railroad 

Mills. This probably results because land use in their 

drainage basins has changed little over the last few 

years. The sites furthest downstream—Allen Creek 

and Blossom Road—showed the greatest number of 

significant differences between the two periods. 

Median concentrations of ammonia + organic 

nitrogen for 1997-99 were significantly lower than the 

period-of-record median at all sites, whereas the 

median suspended solids concentration for 1997-99 

showed a significant difference at only one site, where 

it was lower than the period-of-record median. 

Dissolved chloride showed a significant difference at 

two of the five sites, and dissolved sulfate showed a 

significant difference at four of the five sites. 

Temporal trends

The Irondequoit Creek basin has undergone rapid 

development over the past several years, resulting in 

an increase in residential land and a corresponding 

decrease in agricultural land. The effects of these 

changes on surface-water quality can be evaluated 

through an analysis of water-quality trends.

A trend, as defined in this report, is a monotonic 

(overall) change in concentration of a chemical 

constituent in water samples from a specific sampling 

site over a specified time period. Trends, regardless of 

magnitude, were considered statistically significant at 

p < 0.05—where p is the probability that an apparent 

trend resulted from chance arrangement of the data, 

rather than an actual change in the trend of the data 

values. The seasonal Kendall test (Hirsch and others, 

1982) is a seasonally adjusted, nonparametric test that 

looks at all possible seasonal pairs of data values and 

counts the number of times that the later value is 

higher (positive difference) or lower (negative 

difference) than the earlier one. Thus, where the 

seasons are monthly, each October value is compared 

with every other October value, November to 

November etc. If no trend is present in the record, the 

number of positive and negative differences would 

tend to be equal. The seasonal Kendall test 

incorporates comparisons of the ranks of data and 

thereby minimizes the effects of outliers on trend 

detection. This test also can be applied to waterquality records with censored data (data reported as 

less than a specified reporting limit), provided that a 

single reporting limit is selected for the entire record.

An estimate of the rate of change in the trend 

slope for the period analyzed was computed according 

to Sen (1968). The trend slope, expressed as the 

change in original units (such as milligrams per liter) 

per year, was computed as the median of all pairwise 

comparisons (each paired difference is divided by the 

number of years separating the pair of observations). If 

more than 10 percent of the data were censored, the 

magnitude of the trend slope was likely to be 

inaccurate, and the trend was not reported (Lanfear 

and Alexander, 1990).

Constituent concentrations typically reflect 

seasonal variations in biochemical or hydrologic 

processes or human activities. The seasonal Kendall 

test accounts for these seasonal differences by 

allowing comparisons only for the same season of 

different years. 

Variability in constituent concentrations resulting 

from short-term variations in streamflow can be 

minimized in trend analysis through regression of 

concentration as a function of flow by use of a 

LOWESS (locally weighted scatterplot smoothing) 

procedure (Cleveland, 1979). The LOWESS procedure 

is a robust method of fitting a smoothed line to 

bivariate data. The degree of distance weighting is 

controlled by adjusting the magnitude of the 

smoothing factor (f). A smoothing factor of 0.5 is 

generally used for water-quality data (and was used for 

this analysis) because it tends to give a good fit to the 

data without masking the essential features of the 

relation or producing abrupt changes in slope. This 

regression produces a residual (flow-adjusted 

concentration) that is then used in the trend test. 

Occasionally, this flow adjustment is unsuccessful; if 

so, the trend is reported as a trend in unadjusted 

concentrations. The techniques used for addressing the 

effects of seasonal variation, streamflow variation, 

missing values, and censored data on trend analysis 

are discussed in detail in Johnston and Sherwood 

(1996) and Sherwood (1999).

Generally, the seasonal Kendall trend test 

produces more reliable results when at least 5 years of 

data are available (Hirsch and others, 1982). Because 

these reports represent 3-year periods of data 

collection, in this case 1997-99, the trend analyses are 

updated for the entire period of record to include the 

most recent 3 years of data. 

Surface Water
32 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Table 14. Statistical summary and results of trend tests for selected constituents at four sites in the Irondequoit Creek basin, 

Monroe County, N.Y., period of record through 1999.

[Units are in milligrams per liter unless otherwise noted, dashes indicate greater than 10-percent censoring. n, number of samples for period of record; Q1, 25th percentile; Q3, 75th percentile; n(s), number of seasons used in trend test; n(t), number of samples used in trend analysis; 

p, significance of trend. Bold type indicates trend is statistically significant at α = 0.05. F (in right column) indicates test was performed on flow-adjusted concentrations, C indicates test was performed on unadjusted concentrations. Locations are shown in fig. 1.] 

Descriptive statistics Trend results

Trend 

Constituent and site code

Period of 

record n Mean Q1 Median Q3 n(s) n(t)

Units 

per year

Percent 

per year p

Ammonia as N, dissolved

Railroad Mills 1992-99 214 0.023 0.010 0.010 0.020 4 31 -- -- 0.719 C

East Branch Allen Creek 1991-99 246 .036 .010 .020 .040 12 81 -- -- .653 F

Allen Creek 1984-99 896 .037 .010 .020 .040 12 160 -- -- .001 F

Blossom Road 1984-99 2791 .044 .010 .020 .030 12 191 -- -- <.001 F

Ammonia + organic nitrogen as N, total

Railroad Mills 1992-99 200 .57 .34 .49 .70 4 31 -0.006 -1.05 .897 F

East Branch Allen Creek 1991-99 250 .71 .48 .68 .88 12 81 -.040 -5.63 <.001 C

Allen Creek 1984-99 899 1.04 .73 1.00 1.30 12 160 -.043 -4.14 <.001 F

Blossom Road 1984-99 2763 .95 .59 .80 1.10 12 191 -.049 -5.18 <.001 F

Nitrite + nitrate as N, total

Railroad Mills 1992-99 221 1.11 .91 1.10 1.30 4 31 -.0003 -.03 1.0 F

East Branch Allen Creek 1991-99 267 1.28 .58 1.20 1.80 12 81 -.057 -4.46 .025 F

Allen Creek 1984-99 916 1.14 .82 1.10 1.40 12 160 -.019 -1.67 <.001 F

Blossom Road 1984-99 2750 1.08 .83 1.00 1.30 12 191 -.002 -.20 .550 F

Phosphorus as P, total

Railroad Mills 1992-99 447 .117 .040 .075 .150 12 88 .002 1.45 .278 F

East Branch Allen Creek 1991-99 550 .164 .065 .100 .188 12 81 .000 .11 .799 F

Allen Creek 1984-99 1276 .132 .060 .100 .160 12 185 -.001 -.48 .359 F

Blossom Road 1984-99 2848 .150 .050 .090 .160 12 191 -.001 -.60 .207 F

Orthophosphate as P, dissolved

Railroad Mills 1992-99 452 .008 .005 .007 .010 12 88 .000 4.09 .011 F

East Branch Allen Creek 1991-99 554 .030 .010 .021 .032 12 81 .000 .97 .484 F

Allen Creek 1984-99 1282 .019 .008 .017 .027 12 185 .000 .78 .132 F

Blossom Road 1984-99 2920 .014 .007 .012 .018 12 191 .000 .21 .706 F

Chloride, dissolved

Railroad Mills 1992-99 450 70 60 69 76 12 88 2.800 4.00 <0.001 C

East Branch Allen Creek 1991-99 551 124 72 99 150 12 81 -.673 -0.54 .852 F

Allen Creek 1984-99 1279 182 100 140 210 12 185 .003 .00 <.001 F

Blossom Road 1984-99 2819 122 96 110 130 12 191 1.735 1.42 <.001 F

Sulfate, dissolved

Railroad Mills 1992-99 441 172 120 160 220 12 88 -2.857 -1.66 .423 C

East Branch Allen Creek 1991-99 545 94 59 84 120 12 81 -.580 -.62 .658 F

Allen Creek 1984-99 1189 71 53 68 86 12 185 -1.235 -1.74 <.001 F

Blossom Road 1984-99 2728 143 110 140 180 12 191 -.549 -.38 .029 F

Turbidity, NTU

Railroad Mills 1992-99 451 37 6.6 18 40 12 88 -.001 -.00 .606 C

East Branch Allen Creek 1991-99 549 30 6.8 16 33 12 81 -.135 -.45 .618 F

Allen Creek 1984-99 910 25 5.8 16 31 12 158 -.167 -.67 .168 C

Blossom Road 1984-99 2210 33 5.7 16 34 6 82 -.033 -.10 .750 C
33

Table 14. Statistical summary and results of trend tests for selected constituents at four sites in the Irondequoit Creek 

basin, Monroe County, N.Y., period of record through 1999 (continued)

Descriptive statistics Trend results

Trend 

Constituent and site code

Period of 

record n Mean Q1 Median Q3 n(s) n(t)

Units 

per year

Percent 

per year p

Total suspended solids

Railroad Mills 1992-99 165 172 76 169 205 4 31 13.67 7.95 .018 F

East Branch Allen Creek 1991-99 174 131 62 100 150 6 46 -.510 -.39 .879 F

Allen Creek 1984-99 382 139 62 107 182 6 86 -.367 -.26 .866 C

Blossom Road 1984-99 902 233 85 142 267 12 168 -2.743 -1.18 -.021 F

Volatile suspended solids

Railroad Mills 1992-99 165 22 10 17 26 4 31 1.277 5.80 .251 F

East Branch Allen Creek 1991-99 173 19 10 15 22 6 46 -.076 -.40 .879 F

Allen Creek 1984-99 382 19 10 16 24 6 86 .360 1.90 .146 C

Blossom Road 1984-99 897 28 12 19 31 12 168 -.116 -.41 .564 F

Irondequoit Creek Basin Sites

Ten constituents were tested for temporal trends 

(table 14); results varied with site and constituent. The 

five nutrients that were tested were ammonia, 

ammonia + organic nitrogen, nitrite + nitrate, total 

phosphorus, and orthophosphate. The other five 

constituents tested for trends were dissolved chloride, 

dissolved sulfate, turbidity, total suspended solids, and 

volatile suspended solids.

Nitrogen and phosphorus: Ammonia + organic 

nitrogen showed significant downward trends at three 

of the four Irondequoit basin sites—from 4.1 percent 

per year at Allen Creek to 5.6 percent per year at East 

Branch Allen Creek. The only site showing no trend 

in ammonia + organic nitrogen was Railroad Mills. 

East Branch Allen Creek and Allen Creek also 

showed downward trends in nitrite + nitrate of 4.5 

percent per year and 1.7 percent per year, 

respectively. Allen Creek and Blossom Road showed 

downward trends in ammonia, but because more than 

20 percent of the data are censored (below the 

detection limit), magnitudes are not reported. 

Orthophosphate showed an upward trend of 4.1 

percent per year at Railroad Mills.

Dissolved chloride and dissolved sulfate: 

Railroad Mills, Allen Creek, and Blossom Road 

showed upward trends in dissolved chloride ranging 

from greater than 0.001 percent per year at Allen 

Creek to 4.0 percent per year at Railroad Mills. 

Trends in chloride are likely to vary among the study 

periods and are a function of the rate of road salt 

application during the winter and the amount of 

impervious area in the drainage basin. Allen Creek 

and Blossom Road showed downward trends in 

dissolved sulfate of 1.7 percent per year and 0.4 

percent per year, respectively. The source of sulfate to 

the Irondequoit Creek basin is primarily atmospheric 

deposition, and, to a lesser extent, dissolution of 

sulfate bearing rocks. (See table 2.).

Suspended solids and turbidity: None of the 

Irondequoit sites showed a trend in turbidity. Railroad 

Mills showed an upward trend of 8.0 percent per year 

in suspended solids, whereas Blossom Road showed a 

downward trend of 1.2 percent per year. 

Northrup Creek and Genesee River

Trend analysis of concentrations in Northrup 

Creek and Genesee River at Charlotte Docks was 

based on samples collected by the Monroe County 

Environmental Health Laboratory at Northrup Creek 

near North Greece and at the Charlotte Pump Station 

about 1.6 mi downstream of the discontinued National 

Stream Quality Accounting Network (NASQAN) site 

04232006 on the Genesee River. Streamflow data 

associated with the Genesee River samples were 

derived from the USGS gaging station about 6 mi 

upstream of the sampling site.

Four significant trends were noted in constituent 

concentrations in Northrup Creek. Ammonia + organic 

nitrogen, total phosphorus, and orthophosphate all 

showed downward trends, while dissolved sulfate 

showed an upward trend (table 15). The downward 

trends in the nutrients, particularly phosphorus (fig. 

19), are a result of the improved phosphorus removal 

capabilities of the wastewater-treatment plant up 

stream of the sampling site. In August of 1995 the 

Surface Water
34 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Spencerport treatment plant began adding iron salts to 

improve the removal of phosphorus from treatmentplant effluent (Sherwood, 1999). 

Four significant trends were also noted in 

constituent concentrations in the Genesee River. Total 

phosphorus and orthophosphate showed significant 

upward trends (1.74 percent per year and 6.65 percent 

per year, respectively), whereas ammonia + organic 

nitrogen and dissolved chloride showed significant 

downward trends of 6.11 percent per year and 0.07 

percent per year, respectively. Trends noted in this 

report should not be compared with trends published 

in previous reports for the Genesee River. Because 

those trends were based on data collected at a different 

sampling location (the discontinued NASQAN site), at 

different sampling frequencies, and by different 

sampling methods.

Chemical Loads and Yields

Chemical load calculations provide an estimate of 

the amount (mass) of a particular constituent moving 

past a given point (gaging station) or into a receiving 

body of water. Chemical loads presented in this report 

were calculated by the ESTIMATOR program (Cohn 

and others, 1992), which uses multivariate linear 

regression to develop a quantitative relation between 

periodic constituent concentrations and daily 

streamflows to estimate daily constituent loads, and 

the minimum-variance unbiased estimator (MVUE) 

procedure to correct for log-retransformation bias 

(Cohn and others, 1989). The ESTIMATOR program 

also uses an adjusted maximum likelihood estimator 

(AMLE) of the moments of lognormal populations to 

estimate values for censored data. 

Table 15. Statistical summary and results of trend tests for selected chemical constituents at Northrup Creek and 

Genesee River, Monroe County, N.Y., period of record through 1999.

[Dashes indicate greater than 10-percent censoring. n, number of samples for period of record. Q1; 25th percentile; Q3, 75th percentile; 

n(s), number of seasons used in trend test; n(t), number of samples used in trend analysis; p, significance of trend. Units are in milligrams 

per liter unless otherwise noted. Bold type indicates trend is statistically significant at α = 0.05. F (in right column) indicates test was performed on flow-adjusted concentrations, C indicates test was performed on unadjusted concentrations. Locations are shown in fig. 1.]

Descriptive statistics Trend results

Site n Mean Q1 Median Q3 n(s) n(t)

Units 

per year

Percent 

per year p

Trend

code

Northrup Creek at North Greece, 

1989-99

Turbidity, NTU 782 23 5.0 11 27 12 114 -0.014 -.06 0.438 F

Total suspended solids 186 160 71 113 184 6 51 -4.375 -2.73 .409 C

Volatile suspended solids 185 23 11 17 26 6 51 -1.000 -4.35 .140 C

Ammonia as N, dissolved 775 .120 .020 .040 .140 12 114 -.002 -1.33 .216 F

Ammonia + organic nitrogen as N, total 779 1.00 .72 .89 1.10 12 114 -.033 -3.29 <.001 F

Nitrite + nitrate as N, total 778 1.52 1.10 1.40 1.70 12 114 -.005 -.35 .521 F

Phosphorus as P, total 779 .365 .160 .260 .520 12 114 -.012 -3.40 .012 F

Orthophosphate as P, dissolved 788 .205 .056 .155 .300 12 114 -.011 -5.51 <.001 F

Chloride, dissolved 789 84 57 74 100 12 114 1.333 1.59 .250 F

Sulfate, dissolved 788 52 41 50 60 12 114 .962 1.85 .050 F

Genesee River at Charlotte Pump 

Station, 1990-99

Turbidity, NTU 1949 36 6.2 14 38 12 120 0.530 1.47 0.093 F

Total suspended solids 532 141 69 106 184 12 81 1.841 1.31 .321 F

Volatile suspended solids 527 12 6.0 9.0 12 12 81 -.086 -.71 .498 F

Ammonia as N, dissolved 1938 .132 .070 .100 .160 12 120 -.003 -2.60 .156 F

Ammonia + organic nitrogen as N, total 1947 .68 .50 .62 .78 12 120 -.042 -6.11 <.001 F

Nitrite + nitrate as N, total 1969 1.04 .70 .90 1.20 12 120 -.005 -.51 .454 F

Phosphorus as P, total 1971 .093 .050 .070 .100 12 120 .002 1.74 .021 F

Orthophosphate as P, dissolved 1979 .022 .013 .018 .026 12 120 .001 6.65 <.001 F

Chloride, dissolved 1981 62 40 52 74 12 120 -.043 -.07 <.001 F

Sulfate, dissolved 1973 71 48 71 91 12 120 -.631 -.89 .104 F
35

The ESTIMATOR program estimates constituent 

concentration from equation 1, where streamflow, 

time, and seasonal indicators (sine and cosine 

transformations of time) serve as explanatory variables 

to remove the effects of seasonality in the data. It then 

computes daily loads (eq. 2), applies the MVUE bias 

correction to those daily estimates, and finally sums 

those estimates to monthly and annual totals. 

 (1)

where

C = constituent concentration, in milligrams 

per liter

Q = discharge at time of sample collection, in 

cubic feet per second 

T = time, in years

ε = error (assumed to be independent and 

normally distributed with a mean and 

variance of zero) 

β’s = parameters of the equation that must be 

estimated from the data, and

 , = centering variables that simplify the 

numerical work and have no effect on the 

load estimates. 

ln[ ] C β0 β1 Q Q ̃ ln[ ] ⁄ β2 Q Q ̃ { } ln[ ] ⁄

2

β3 T T ̃ [ ]β ⁄ 4 T T ̃ [ ] ⁄

2

β5 [ ] 2πT

β6cos[ ]ε 2πT +

sin +

+ +

+ +

= +

Q ̃ T

 ̃

Figure 19. Concentrations of (A) total phosphorus and (B) orthophosphate along with Locally 

Weighted Scatterplot Smooth (LOWESS) trendlines, before and after implementation of 

improved treatment for phosphorus at the Spencerport wastewater-treatment plant, at 

Northrup Creek at North Greece, Monroe County, N.Y., for period of record through 1999.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 -0.25

0

0.5

1

1.5

2

2.5

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 -0.1

0

0.2

0.4

0.6

0.8

0.9

CONCENTRATION, IN MILLIGRAMS PER LITER CONCENTRATION, IN MILLIGRAMS PER LITER

PHOSPHORUS, TOTAL

LOWESS TREND LINE

ORTHOPHOSPHATE, DISSOLVED

LOWESS TREND LINE

Improved phosphorus treatment at

Spencerport wastewater-treatment plant

Improved phosphorus treatment at

Spencerport wastewater-treatment plant

A

B

Surface Water
36 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

The corresponding load L is given by

 where

K = conversion factor,

Q = daily mean discharge, in cubic feet per 

second, and all other variables are as defined 

for equation 1.

The precision of the estimated loads can be 

described in terms of a confidence interval that is 

based on the estimated mean and the standard error of 

prediction. At the 95-percent confidence interval 

(α = 0.05), the confidence limits are the estimated load 

+ 1.96 times the standard error of prediction. The 

value 1.96 is from a statistical table for a Student’s tdistribution at the α/2 quantile with a large number of 

samples (more than 250). If, for example, the monthly 

load estimated for chloride was 145 tons, and the 

standard error of prediction was 12 tons, the 

approximate 95-percent confidence limits would be:

145 + (1.96 × 12) = 121.5 to 168.5 tons.

The wider the confidence limits, the greater the 

uncertainty and, hence, the less reliable the load 

estimates. A more detailed explanation of the MVUE 

method is given in Cohn and others (1992).

 Knowledge of trends in the loads of chemical 

constituents carried by streams and their tributaries is 

important in assessing the effectiveness of 

management practices already in use and in evaluating 

the effect of land-use changes within the watershed on 

receiving bodies of water.

Some of the parameter estimates (coefficients) for 

the terms of the equation used to calculate 

concentrations (eq. 1) can be directly related to basin 

characteristics or to physical process. For example, β1, 

which corresponds to the linear dependence of 

concentration on streamflow, may depend on the 

source of the constituent—negative values indicate a 

dilution effect, suggesting point sources; near-zero 

values imply no effect from dilution, as is 

characteristic of some dissolved constituents; and 

positive values are generally indicative of sedimentrelated nonpoint sources. The value of β3 corresponds 

to the magnitude of the log-linear component of the 

upward or downward time trends in constituent load. 

R2 (coefficient of variation) of the concentration is the 

variability explained by the equation for the logarithm 

of concentration and R2

 load is the variability 

explained by the equation for the logarithm of load. 

The dependence of concentration on flow (β1), the 

direction and magnitude of trends in loads (β3), and 

coefficients of variation (R2

) for concentration and 

load are summarized in table 16.

Flow related coefficients (β1 values) for total 

suspended solids and volatile suspended solids at most 

sites indicate a statistically significant positive 

dependence on flow, implying a probable nonpoint 

source for these constituents (table 16). The lower β1

coefficients for these constituents at Irondequoit Creek 

at Railroad Mills, East Branch Allen Creek, and 

Northrup Creek indicate a mix of point and nonpoint 

sources at these sites. The β1 coefficients for dissolved 

chloride and dissolved sulfate at all sites indicate a 

significant negative dependence on flow, which 

implies the strong probability of point sources for 

these constituents. The β1 coefficients for nutrients 

suggest a combination of point and nonpoint sources 

at some sites, whereas ammonia showed a strong 

negative dependence on flow at Northrup Creek and 

Black Creek at Churchville implying point sources at 

these sites for this constituent. The β1 coefficient for 

total phosphorus at Irondequoit Creek at Railroad 

Mills showed a significant indication of a nonpoint 

source for that constituent.

Irondequoit Creek at Railroad Mills and Northrup 

Creek show significant upward trends in loads of total 

and volatile suspended solids for water years 1997-99, 

whereas Oatka Creek at Garbutt showed a significant 

downward trend in loads of total and volatile 

suspended solids (-35.1 percent and -51.4 percent, 

respectively) for the 1998-99 water years (period of 

record). The large upward trends in these constituents 

at Irondequoit Creek at Railroad Mills and Northrup 

Creek are related to the peak-of-record high flow of 

January 8, 1998, which was fairly close to the end of 

the 1997-99 period, whereas the large downward trend 

at Oatka Creek at Garbutt reflects that stormflow’s 

occurrence near the beginning of that site’s period of 

record (1998-99). The direction and magnitude of 

trends in loads of all nutrients except nitrite + nitrate 

were mixed; nitrite + nitrate showed decreasing trends 

at all sites; these ranged from 4.3 percent per year at 

Northrup Creek to 39 percent per year at Black Creek 

at Churchville. Orthophosphate was the nutrient with 

increasing trends at the greatest number of sites; these 

ranged from 1.4 percent per year at East Branch Allen 

Creek to 24 percent per year at Railroad Mills, but it 

L KQ (β0 β1 Q Q ̃ ln[ ] ⁄ β2 Q Q ̃ { } ln[ ] ⁄

2

β3 T T ̃ [ ]β ⁄ 4 T T ̃ [ ] ⁄

2

β5 [ ] 2πT

β6cos[ ]ε 2πT + )

sin +

+ +

+ +

= exp + (2)
37

Table 16. Equation parameter estimates showing linear dependence of concentration on flow (β1) and magnitude (β3), in 

percent per year, of estimated trends in loads for selected constituents, and R2 values for concentrations and loads at four 

sites in the Irondequoit Creek basin, Genesee River, and four sites in western Monroe County, N.Y., 1997-99.

[Bold type indicates figure is statistically significant at α = 0.05. Negative value for parameter β1 indicates dilution effect; 

positive or negative value for parameter β3 indicates upward or downward trend, respectively. Dashes indicate no/insufficient data. 

Locations are shown in fig. 1.] 

1 β1 estimates were retransformed from log units as (eβ1 - 1); β3 estimates were retransformed from log units as 100 (eβ3 - 1). 

Constituent

Site

Equation 1 

parameter1

Total 

suspended 

solids

Volatile 

suspended 

solids

Ammonia 

as N, 

dissolved

Ammonia 

+ organic 

nitrogen 

as N, total

Nitrite 

+ nitrate

as N, total

 Phosphorus

as P, total

Orthophosphate

as P, 

dissolved

 Chloride,

dissolved

 Sulfate,

dissolved

Irondequoit Creek 

at Railroad Mills

β1 0.249 0.021 0.516 0.290 - 0.164 0.832 0.475 - 0.175 - 0.324

β3 89.1 87.0 -20.0 - 4.33 - 8.92 12.1 24.0 .56 - .69

R2 Conc 35.3 33.5 61.9 25.6 53.3 39.8 68.5 38.0 74.6

R2 Load 60.6 60.2 85.9 78.8 93.9 70.8 89.1 91.5 80.7

East Branch

Allen Creek at 

Pittsford

β1 .442 .244 - .032 .151 .205 .358 .396 - .099 - .260

β3 21.9 26.4 10.3 - 4.36 - 22.5 - 10.4 1.38 - 6.64 - 2.58

R2 Conc 44.5 32.5 32.1 33.7 75.5 64.7 66.7 76.0 62.5

R2 Load 86.1 85.1 77.3 95.8 96.4 92.6 90.1 94.0 87.1

Allen Creek near 

Rochester

β1 .683 .436 .021 .048 .008 .332 .177 - .189 - .186

β3 18.2 3.07 - 6.27 - 21.7 - 11.5 - 3.43 3.36 - 7.81 3.41

R2 Conc 60.0 51.5 23.8 28.8 46.1 54.6 77.0 66.1 57.7

R2 Load 87.7 88.7 80.6 88.0 94.8 86.8 91.7 88.3 95.0

Irondequoit Creek 

at Blossom Road

β1 1.45 .940 .387 .410 - .009 - .001 .265 - .183 - .307

β3 -5.34 -6.11 17.8 - 12.1 - 7.73 9.00 21.3 - 2.92 .89

R2 Conc 46.2 40.3 33.5 32.8 63.4 53.0 66.5 52.6 59.1

R2 Load 73.9 71.7 76.0 86.0 96.8 81.8 89.3 93.4 75.6

Northrup Creek at 

North Greece

β1 .323 .164 - .817 .038 - .211 .179 - .134 - .111 - .091

β3 65.6 52.1 - 11.3 - 8.85 - 4.26 - .520 4.13 - 5.34 10.1

R2 Conc 41.8 41.9 80.0 28.2 46.9 61.2 85.6 77.4 46.5

R2 Load 74.5 79.6 88.6 85.8 90.6 77.1 86.2 94.9 93.5

Genesee River at 

Charlotte Pump

Station

β1 1.41 1.28 - .424 - .031 .052 .477 - .019 - .213 - .292

β3 - 3.35 - 8.06 - 11.8 - 4.31 - 5.36 4.89 3.47 - 1.30 .190

R2 Conc 50.3 36.1 61.8 10.0 53.6 50.2 46.9 56.1 81.3

R2 Load 78.8 66.0 73.6 90.6 96.1 92.0 83.9 94.9 94.9

Black Creek at 

Churchville

β1 -- -- - .806 .082 .308 .275 .140 - .132 - .232

β3 -- -- 81.1 11.4 - 39.1 53.6 - 26.3 .89 18.0

R2 Conc -- -- 43.6 21.4 71.8 51.1 64.6 63.9 79.9

R2 Load -- -- 64.7 95.3 95.3 92.7 92.0 99.0 94.7

Oatka Creek at 

Garbutt

β1 1.206 .706 .141 .389 .120 .358 .862 - .140 - .402

β3 - 35.1 - 51.4 20.6 4.53 - 18.5 - 10.4 22.1 - 13.5 - 7.51

R2 Conc 61.5 54.3 56.3 34.3 87.1 64.7 62.9 67.8 91.2

R2 Load 89.4 86.2 89.9 92.1 99.2 92.6 92.5 99.0 87.5

Honeoye Creek at 

Honeoye Falls

β1 -- -- - .012 .071 .238 .310 .138 - .092 - .078

β3 -- -- 80.2 .23 - 12.9 3.72 - 41.3 15.1 6.80

R2 Conc -- -- 30.8 17.3 59.3 48.0 65.3 68.6 55.6

R2 Load -- -- 92.7 96.8 91.0 96.9 96.7 99.3 98.1

Surface Water

,
38 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

showed a decreasing trend of 41 percent per year at 

Honeoye Creek at Honeoye Falls. The greatest 

increasing trend in total phosphorus (54 percent per 

year) was at Black Creek. Trends in constituent loads 

for Black Creek, Oatka Creek, and Honeoye Creek 

should be interpreted with caution however, because 

of the relatively short (2 year) period of data 

collection. Reliable trend analysis generally requires at 

least 5 years of data.

The loads of most constituents generally are 

greatest during the spring (February through May), 

when snowmelt and spring rains cause high runoff. 

The loads of constituents that were analyzed for total 

concentration (suspended and dissolved), such as 

ammonia + organic nitrogen, nitrite + nitrate, and 

total phosphorus, were greatest at these times. In 

contrast, the concentrations of dissolved 

constituents, such as orthophosphate, ammonia 

nitrogen, chloride, and sulfate, vary with flow to a far 

lesser degree and usually are diluted by high flows; 

however, the large volumes of flow during spring 

generally are enough to produce large loads of these 

constituents despite dilution.

Irondequoit Creek Basin Sites

Total annual loads entering Irondequoit Bay from 

the Irondequoit Creek basin are estimated by 

multiplying the calculated loads for Irondequoit Creek 

at Empire Boulevard (Coon, 2000) by 1.10 to account 

for the additional drainage area between Empire 

Boulevard and the bay. Residence times of 

constituents in the bay range from several months to 

several years (Bubeck and Burton, 1989); thus, a 

minor change in load of some of the conservative 

constituents could have a major effect on water quality 

of the bay because those constituents tend to 

accumulate in the sediments of the bay, where they are 

subject to resuspension and release when these 

sediments are disturbed.

Annual loads of chemical constituents transported 

to Irondequoit Bay by Irondequoit Creek were 

consistent with annual runoff (table 17)—greatest 

annual loads occurred during 1998, when the runoff 

(15.5 in.) was highest. The percentage of annual loads 

transported during the spring snowmelt period 

(February through May), when runoff is usually 

highest, were lower than would be expected for 1997-

98. This was because water years 1997 and 1998 had 

several months outside the usual high runoff period 

when precipitation exceeded normal by a considerable 

amount (table 1). Water year 1997 had 4 months 

outside the February through May period in which 

total precipitation exceeded normal by 63 percent, and 

water year 1998 had 5 months in which total 

precipitation exceeded normal by 97 percent. Water 

year 1999 was more typical in that the greatest loads 

of most constituents were transported during the 

spring snowmelt and runoff period. The percentage of 

annual loads of nitrite + nitrate carried during the 

spring snowmelt and runoff period was consistent 

among all 3 years, regardless of differences in runoff.

Table 17. Annual loads of selected constituents transported by Irondequoit Creek to Irondequoit Bay, Monroe 

County, N.Y., water years 1997-99, and percentage of total annual load transported from February through May. 

[Annual loads are in tons per year.]

Constituent

Annual 

runoff

(inches)

Water year

or

period

Total 

suspended

solids

Volatile 

suspended 

solids

Ammonia, 

dissolved 

Ammonia 

+ organic

nitrogen, 

total

Nitrite + 

nitrate, 

total

 Phosphorus,

total

Ortho 

phosphate, 

dissolved

Chloride 

dissolved 

Sulfate 

dissolved

A. Annual loads (multiplied by 1.10 to account for drainage area between Empire Boulevard and mouth)

1997 11,600 1,660 6.18 96.8 196 12.8 2.34 21,600 16,700 13.0

1998 20,800 2,990 6.79 107 175 24.3 3.76 23,600 18,500 15.5

1998 14,300 2,010 5.92 71.8 153 20.2 2.39 18,200 15,600 10.7

97-99 (Mean) 15,600 2,220 6.30 91.9 175 19.1 2.83 21,100 16,900 13.0

B. Percentage of total annual loads transported from February through May (spring snowmelt and runoff period)

1997 24 22 36 38 49 30 22 44 36 40

1998 19 17 30 34 49 22 18 42 35 37

1999 40 32 49 57 48 48 37 57 45 56

97-99 (Mean) 28 24 38 43 49 33 26 48 39 44
Surface Water 39

0

600

200

400

0

0.4

0.1

0.2

0.3

0

1.5

0.5

1.0

0

0.12

0.02

0.04

0.06

0.08

0.10

1997

1998

1999

0

3

1

2

0

0.4

0.1

0.2

0.3

0

250

50

100

150

200

0

200

50

100

150

TOTAL SUSPENDED SOLIDS AMMONIA

AMMONIA + ORGANIC

NITROGEN

NITRITE + NITRATE TOTAL

PHOSPHORUS

ORTHOPHOSPHATE CHLORIDE,

DISSOLVED

SULFATE,

DISSOLVED

EXPLANATION

BR AC EB RM NC BC OC HC BR AC EB RM NC BC OC HC BR AC EB RM NC BC OC HC

0

40

10

20

30

VOLATILE SUSPENDED 

SOLIDS

ANNUAL YIELDS, IN TONS PER SQUARE MILE

Figure 20. Annual yield of selected constituents at four sites in the Irondequoit Creek basin (Irondequoit Creek at 

Blossom Road, Allen Creek, East Branch Allen Creek, and Irondequoit Creek at Railroad Mills) and four western 

sites (Northrup Creek, Black Creek, Oatka Creek, Honeoye Creek) in Monroe County, N.Y., water years 1997-

99. (Locations are shown in fig. 1.)

BR AC EB RM NC BC OC HC

BR AC EB RM NC BC OC HC

BR AC EB RM NC BC OC HC

BR AC EB RM NC BC OC HC

BR AC EB RM NC BC OC HC

BR AC EB RM NC BC OC HC

BR Irondequoit Creek at Blossom Road

AC Allen Creek near Rochester

EB East Branch Allen Creek at Pittsford

RM Irondequoit Creek at Railroad Mills

NC Northrup Creek at North Greece

BC Black Creek at Churchville

OC Oatka Creek at Garbutt

HC Honeoye Creek at Honeoye Falls
40 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Table 18. Mean annual yields of selected constituents at four sites in the Irondequoit Creek basin and four western sites in 

Monroe County, N.Y., for indicated water years.

[All values are in tons per square mile. Dashes indicate no/insufficient data: Locations are shown in fig. 1.]

Water year 

Total

suspended 

solids

Volatile 

suspended 

solids

Ammonia, 

dissolved 

Ammonia + 

organic 

nitrogen, 

total

Nitrite +

nitrate,

total

Phosphorus, 

total

Orthophosphate, 

dissolved

Chloride, 

dissolved 

Sulfate, 

dissolved

Runoff, 

in 

inches

Irondequoit Creek at Blossom Road

1984-88 170 19.0 0.038 1.13 1.15 0.138 0.015 99.7 112 12.67

1989-93 277 35.1 .030 1.18 1.09 .240 .010 115 111 13.88

1994-96 143 17.7 .013 .64 .91 .140 .011 114 106 11.54

1997-99 250 21.7 .017 .61 1.00 .220 .013 123 109 13.27

Allen Creek near Rochester

1984-88 143 17.4 .044 1.26 1.30 .146 .021 161 72.1 13.86

1989-93 117 19.0 .040 1.06 1.14 .140 .020 173 60.4 13.64

1994-96 142 17.9 .018 .67 .91 .110 .018 178 51.4 11.12

1997-99 132 16.4 .020 .60 1.04 .160 .023 173 49.8 13.26

East Branch Allen Creek at Pittsford

1991-93 199 28.5 .050 1.34 2.45 .260 .030 136 102 19.62

1994-96 164 21.3 .042 1.05 1.71 .170 .033 143 97.0 15.84

1997-99 112 16.3 .027 .55 1.42 .160 .027 121 67.1 17.45

Irondequoit Creek at Railroad Mills

1992-93 124 16.9 .010 .62 .73 .100 .010 42.3 124 15.68

1994-96 173 20.3 .010 .55 .99 .100 .007 62.8 255 12.02

1997-99 190 23.2 .017 .49 1.08 .123 .010 76.9 154 13.77

Northrup Creek at North Greece

1990-93 240 30.8 .160 1.37 1.55 .380 .180 84.1 48.3 15.09

1994-96 246 29.6 .210 1.05 1.57 .320 .130 107 54.6 14.22

1997-99 159 20.5 .207 1.10 1.82 .290 .090 121 66.8 18.54

Black Creek at Churchville

1999 -- -- .014 .37 1.03 .041 .012 27.0 91.0 --

Oatka Creek at Garbutt

1998-99 48.0 9.6 .038 .58 1.94 .026 .001 44.3 116 --

Honeoye Creek at Honeoye Falls

1999 -- -- .004 .14 .20 .026 .004 12.3 8.54 --

Yields (load per unit area) are more helpful than 

loads in basin-to-basin comparisons. For example, one 

basin may have a greater total load than another 

simply because it has a larger area; yet, it may have a 

smaller yield than the other basin. Thus, the 

interpretation as to the difference in the yields from 

each basin might be quite different than for differences 

in loads. Annual yields (in tons per square mile of 

basin above the measuring point) for the four sites 

representing the Irondequoit Creek subbasins 

(Irondequoit Creek at Blossom Road, Allen Creek, 

East Branch Allen Creek, and Irondequoit Creek at 

Railroad Mills), and four sites in western Monroe 

County (Northrup Creek, Black Creek, Oatka Creek, 

Honeoye Creek), are summarized in figure 20. Among 

the four Irondequoit Creek basin sites, mean annual 

yields of nutrients for 1997-99 generally were 

comparable to those of previous report periods and 

from site to site. Mean annual 1997-99 yields of total 

phosphorus and orthophosphate at Allen Creek were 

higher than those of the previous periods. Mean annual 

yields of all constituents at East Branch Allen Creek 

have decreased steadily since the first reporting period 

(1991-93) (table 18); these decreases in yield result 

from the construction of a stormwater-detention basin 

in the summer of 1995 on East Branch Allen Creek 

about 1.1 mi upstream of the monitoring site. The 

stormwater stored in the pond during high flows is 

released slowly through East Branch Allen Creek and 

used for irrigation downstream during the summer. 
41

Detention basins have been shown to reduce 

concentrations of contaminants contained in storm 

runoff (Zarriello and Sherwood, 1993 and Sherwood, 

2001b). A statistical analysis (Wilcoxon rank sum test) 

was used to compare constituent concentrations from 

before construction of the detention basin to those 

obtained after. Because water in East Branch Allen 

Creek during the navigation season is comprised 

primarily of water diverted from the canal (table 11), 

only concentrations obtained during the nonnavigation season were used for the comparison. Mean 

concentrations of all constituents, except chloride and 

sulfate, were lower after construction of the detention 

basin and suspended solids and nitrogen ammonia + 

organic were significantly lower (table 19). 

Irondequoit Creek at Railroad Mills, in contrast, 

shows an increase in yield of all constituents except 

ammonia and dissolved sulfate over the three reporting 

periods. The higher yields for the 1997-99 period 

result from the large amount of runoff for 1998. Yields 

of chloride at the downstream sites, which drain 

urbanized areas, are little changed since the first 

report, Johnston and Sherwood (1996) and range from 

173 ton/mi2

 at Allen Creek to 121 ton/mi2 at East 

Branch Allen Creek. Yields of chloride upstream at 

Railroad Mills, whose drainage area is more 

agricultural and has a lower percentage of impervious 

area, is considerably lower (76.9 ton/mi2

) than at the 

other Irondequoit Creek sites.

Western Monroe County Sites

Mean annual yields of nutrients, at Northrup 

Creek for water years 1997-99 were higher than at any 

of the other Monroe County sites. Ammonia and 

ammonia + organic nitrogen yields were little changed 

from previous periods, whereas nitrite + nitrate was 

higher and total phosphorus and orthophosphate were 

lower. The lower mean annual loads of total 

phosphorus and orthophosphate for 1997-99 are a 

continued indication of the improved phosphorus 

treatment at the Spencerport sewage-treatment plant 

begun in the summer of 1995. The apparent lack of 

greater improvement for total phosphorus is a result of 

Table 19. Median concentrations of selected constituents 

during the non-navigation season at East Branch Allen 

Creek before and after construction of the detention pond 

at Jefferson Road, Monroe County, N.Y.

[Units are milligrams per liter, unless otherwise noted. Bold type

indicates difference is significant at α=0.05. Location is shown in 

fig. 1.]

Constituent or property Before After

Flow (cubic feet per second) 15.0 14.0

Turbidity (nephlometric turbidity units) 13.5 10.0

Total suspended solids 136 76.0

Volatile suspended solids 20.0 14.0

Ammonia, dissolved 0.030 0.020

Ammonia + organic nitrogen, total 0.80 0.60

Nitrite + nitrate, total 1.8 1.6

Phosphorus, total 0.080 0.075

Orthophosphate, dissolved 0.013 0.013

Chloride, dissolved 134 170

Sulfate, dissolved 68.5 62.0

Surface Water

Table 20. Annual constituent loads with associated error and annual yield, for Genesee River at Charlotte Pump Station, 

Monroe County, N.Y., water years 1997-99.

[Loads are annual total in thousands of tons. Error multiplied by 1.96 and added to and subtracted from the estimated load gives

approximate 95-percent confidence limits of load estimate. Yield in tons per square per mile. Location is shown in fig. 1.] 

Constituent

1997 1998 1999 Yield

Load Error Load Error Load Error 1997 1998 1999

Suspended solids 417 72 560 121 161 37 169 227 65.3

Volatile solids 31.3 8.12 42.7 13.3 12.1 4.58 12.7 17.3 4.90

Ammonia as N, dissolved .279 .023 .262 .021 .158 .013 .113 .106 .064

Ammonia + organic nitrogen as N, 

total 1.75 .14 1.87 .15 .83 .065 .71 .76 .34

Nitrite + nitrate as N, total 3.41 .19 3.72 .21 1.71 .10 1.38 1.51 .69

Phosphorus as P, total .40 .043 .53 .063 .17 .019 .16 .21 .069

Orthophosphate as P, dissolved .069 .006 .077 .007 .035 .003 .028 .031 .014

Chloride, dissolved 120 5.32 129 5.67 71.4 3.24 48.6 52.3 28.9

Sulfate, dissolved 156 5.69 166 5.99 99.1 3.68 63.2 67.3 40.2
42 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

the higher daily mean streamflows for the years after 

phosphorus control than those in the preceding period. 

Total phosphorus, which adheres to suspended 

particulate matter, generally shows a positive 

correlation with streamflow. Although Northrup 

Creek’s drainage area is mainly agricultural, the 

relatively high nutrient yields (compared to the 

Irondequoit Creek basin) are derived primarily from 

sewage-treatment-plant discharge upstream from the 

sampling site and, to a lesser extent, from fertilizers, 

agricultural runoff, water diverted from the New York 

State Barge Canal, septic systems, and atmospheric 

deposition. Mean annual yields of total suspended 

solids and volatile suspended solids for 1997-99 were 

considerably lower (159 ton/mi2

 and 20.5 ton/mi2, 

respectively) than for the two previous periods, even 

though runoff for 1997-99 was slightly greater (table 

18). Mean annual yields of chloride and sulfate for 

1997-99 were higher than for the two previous periods 

as a result of the greater runoff during that period. 

Mean annual yields of chloride at Black Creek, Oatka 

Creek and Honeoye Falls are much lower than those at 

Northrup Creek and about the same as those in the 

Genesee River. The higher chloride yields at Northrup 

Creek are probably a result of discharge from the 

Spencerport sewage-treatment plant.

Annual loads of constituents in the Genesee River 

(table 20) were estimated from streamflow data 

collected at the Genesee River at Rochester gaging 

station (04232000) and concentration data collected at 

the Charlotte Pump Station, about 5 mi downstream 

(fig 1). Yields for all constituents were within the 

range of those noted for the other sites in Monroe 

County. Loads and yields of all constituents for water 

year 1999 were considerably lower than for water 

years 1997-98. The annual mean flow of 1,660 ft3

/s for 

1999 was only 60 percent of the 3-year mean annual 

flow of 2,760 ft3

/s for 1997-99.

SUMMARY AND CONCLUSIONS

Many years of systematic collection of 

hydrologic data in Monroe County have provided a 

foundation for a comprehensive assessment of the 

county’s water resources. Long-term records of 

precipitation and unregulated streamflow provide the 

basis for determining the normality of much shorter 

periods of record, such as the 1997-99 water-year 

period analyzed in this report. 

Precipitation records collected by the National 

Weather Service at Rochester indicate that average 

annual rainfall for 1997-99 was 38.44 in., 6.48 in. 

above normal. Precipitation for 1998 was 13.9 in. 

above normal, that for 1997 was 6.82 in. above 

normal, and that for 1999 was 1.3 in below normal. A 

storm on January 8, 1998 produced period-of-record, 

or near period-of-record, flows at the Irondequoit 

basin sites and contributed to the above normal 

precipitation and high annual constituent loads for 

1998. Annual yields of chemicals deposited on the 

Irondequoit Creek Basin from atmospheric sources 

during 1997-99 were generally higher than during the 

previous (1984-96) report period; the ammonia yield 

was 144 percent higher, the dissolved potassium yield 

was 118 percent higher and the sodium yield 87 

percent higher. These high yields are attributed partly 

to the above normal precipitation during 1997-99 and 

in the case of ammonia, is probably a result of 

increased local applications of fertilizer upwind of the 

collection site. Decreases were noted in yields of 

magnesium (6.4 percent), orthophosphate (30 

percent), and sulfate (36 percent).

Loads of all nutrients deposited on the 

Irondequoit basin from atmospheric sources during 

1997-99 greatly exceeded those transported by 

Irondequoit Creek. The ammonia load deposited on 

the basin was 139 times the load transported at 

Blossom Road (the most downstream site); the 

ammonia + organic nitrogen load was 6.3 times 

greater, orthophosphate 7.5 times greater, total 

phosphorus 1.3 times greater and nitrite + nitrate 1.5 

times greater. Average yields of dissolved chloride and 

dissolved sulfate from atmospheric sources were much 

smaller than those transported by streamflow at 

Blossom Road—chloride was about 2 percent and 

sulfate about 8 percent of the amount deposited. 

Ground-water levels in Ellison Park wells 

indicate that water-table gradients are subject to 

reversals in lateral flow in the aquifer. Trend analysis 

of ground-water levels in Ellison Park wells for the 

period of record through 1999 showed upward trends 

of 0.11 percent per year at Mo 659 (well finished in 

the lower confined part of the aquifer), and 5.9 percent 

per year at Mo 667 (well finished in the upper 

unconfined part of the aquifer). 

Concentrations of chemical constituents in 

Ellison Park wells showed a total of 75 statistically 

significant trends. The well with the highest number 

of significant trends was Mo 3, where 11 of the 
43

constituents showed a downward trend, and 1 showed 

an upward trend. the well with the fewest statistically 

significant trends (4) was Mo 664. Turbidity was the 

constituent that showed a trend at the greatest number 

of wells (4 upward, and 4 downward). Common ions 

were the constituents that showed the greatest 

number of trends among wells, and nutrients showed 

the fewest. 

Monthly mean streamflow for the four monitored 

streams in the Irondequoit Creek basin were generally 

at or near normal values (25th to 75th percentile), 

except for January which was above 75th percentile, 

and April and May which were near or below the 25th 

percentile. Streamflow at the four monitored sites in 

western Monroe County was near or above normal 

(75th percentile) for October through February, 

slightly below normal for April, and near or slightly 

above normal for the remainder of the 1998 water 

year. Trend analysis of the monthly mean flows at sites 

in the Irondequoit Creek basin and Northrup Creek 

indicated a significiant downward trend in streamflow 

at Allen Creek (1.25 percent per year; 1984-99) and an 

upward trend at Northrup Creek (4.3 percent per year; 

1989-99) for the period during which water quality 

data have been collected at these sites.

Streamflow temperatures in the Irondequoit 

Creek basin were typical of the large, low-gradient 

streams in New York. Maximum daily temperatures 

during 1997-99 exceeded 22.0o

 C on many days 

during the summer months at all sites, but daily mean 

temperatures for those days generally were lower than 

22.0o

 C, and those at Railroad Mills never exceeded 

that limit. No minimum temperatures at any of the 

sites exceeded 22.0o

 C. 

Median concentrations of most constituents were 

relatively uniform among the four sites in the 

Irondequoit Creek basin. Among the nutrients, nitrite 

+ nitrate showed the greatest range in concentration, 

from 0.71 mg/L at East Branch Allen Creek to 1.1 mg/

L at Irondequoit Creek at Railroad Mills. The highest 

median concentration of ammonia + organic nitrogen 

(0.51 mg/L) was at East Branch Allen Creek, and the 

lowest (0.34 mg/L) was at Railroad Mills. Median 

concentrations of total phosphorus ranged from 0.075 

mg/L to 0.095 mg/L whereas those for orthophosphate 

ranged from 0.008 mg/L to 0.020 mg/L. 

Orthophosphate was the constituent with the greatest 

number of statistically significant differences in 

median concentration among sites in the Irondequoit 

Creek basin. The highest median concentration of 

chloride (158 mg/L) occurred at Allen Creek, 

whereas the highest median concentration of sulfate 

(152 mg/L) was at Irondequoit Creek at Railroad 

Mills. Median concentrations of these constituents for 

1997-99, were higher than for previous periods and 

showed statistically significant differences among 

most of the sites. Median concentrations of total 

suspended solids were highest at Allen Creek and 

Railroad Mills (139 and 136 mg/L), respectively. 

Median concentrations of nutrients in Northrup Creek 

were higher than those found at the Irondequoit basin 

sites, but lower than during previous periods because 

of the improved treatment of phosphorus upstream at 

Spencerport. Median concentrations of constituents at 

the other western Monroe County sites were within the 

range of those noted at the Irondequoit sites. 

Period-of-record trends for constituents at sites 

in the Irondequoit Creek basin differed from site to 

site and in magnitude and direction. Statistically 

significant downward trends in the concentration of 

ammonia + organic nitrogen, ranging from 4.1 

percent per year at Allen Creek to 5.6 percent per year 

at East Branch Allen Creek, were noted at three of the 

four Irondequoit Creek basin sites. Railroad Mills 

was the exception, where ammonia + organic 

nitrogen showed no trend. Orthophosphate showed an 

upward trend of 4.1 percent per year at Railroad 

Mills. Dissolved chloride showed upward trends at 

Railroad Mills, Allen Creek, and Blossom Road; 

these ranged from greater than 0.01 percent per year 

at Allen Creek to 4.0 percent per year at Railroad 

Mills. Dissolved sulfate showed downward trends of 

1.7 percent per year at Allen Creek and 0.4 percent 

per year at Blossom Road. Suspended solids showed 

an upward trend of 13.7 percent per year at Railroad 

Mills and a downward trend of 2.7 percent per year at 

Blossom Road.

Northrup Creek showed statistically significant 

downward trends in ammonia + organic nitrogen (3.3 

percent per year), total phosphorus (3.4 percent per 

year), and orthophosphate (5.5 percent per year), and 

an upward trend in sulfate (1.8 percent per year). The 

Genesee River showed downward trends in ammonia 

+ organic nitrogen (6.1 percent per year) and chloride 

(0.1 percent per year), and upward trends in total 

phosphorus (1.7 percent per year) and orthophosphate 

(6.6 percent per year).

Loads of chemical constituents transported to 

Irondequoit Bay during 1997-99 were generally 

greater than those for 1994-96. Total suspended solids 

Summary and Conclusions
44 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

were transported at the rate of 15,600 ton/yr, of which 

volatile suspended solids constituted about 2,220 tons. 

Nutrient transport to the bay averaged 91.9 ton/yr for 

ammonia + organic nitrogen, 175 ton/yr for nitrite + 

nitrate, 6.3 ton/yr for ammonia, 19.1 ton/yr for total 

phosphorus, and 2.8 ton/yr for orthophosphate. 

Dissolved chloride transported to the bay averaged 

21,100 ton/yr, and sulfate transported averaged 16,900 

ton/yr.

Generally, mean annual yields of constituents 

were similar among the four Irondequoit Creek basin 

sites. Irondequoit Creek at Railroad Mills had the 

highest yields of total and volatile suspended solids 

(190 and 23.2 ton/mi2

, respectively) and the lowest 

yield of chloride (76.9 ton/mi2

). Allen Creek had the 

highest yield of dissolved chloride. East Branch Allen 

Creek had the highest yields of all nutrients in the 

Irondequoit basin. Northrup Creek had higher yields 

of all nutrients than any of the Irondequoit basin sites. 

The yields of all constituents at East Branch Allen 

Creek decreased after 1995 as a result of to the 

construction of a stormwater-detention basin on the 

main channel of the creek upstream the monitoring 

site. The high yields of nutrients at Northrup Creek are 

a result of the discharge from an upstream waste-water 

treatment plant and, to a lesser extent, agricultural 

runoff. Annual yields of constituents in the Genesee 

River were within the range of those found at Northrup 

Creek and the Irondequoit basin sites.

Surface-water quality data collected during 1997-

99 showed that streamwater quality was similar to that 

of the previous periods of record, but with some 

differences. Concentrations of ammonia + organic 

nitrogen, nitrite + nitrate, total phosphorus, and 

orthophosphate for 1997-99 were either similar to, or 

lower than those for the preceding period of record at 

all sites. Concentrations of dissolved chloride were 

higher at all sites, and those for dissolved sulfate were 

lower. Northrup Creek continues to have the highest 

concentrations of all nutrients, but those 

concentrations are generally declining in response to 

additional treatment by the sewage-treatment plant at 

Spencer port. Chloride concentrations at Northrup 

Creek however, continue to increase in response to 

increasing development within the basin and 

increased runoff.

The data revealed some general differences 

among basins for the 1997-99 period. Northrup Creek 

had the highest concentrations of nutrients, whereas 

Irondequoit Creek at Railroad Mills, with the 

exception of nitrite + nitrate had the lowest. 

Irondequoit Creek at Railroad Mills, which is largely 

agricultural, had the lowest concentrations of 

chloride, and the highest concentrations of sulfate. 

Allen Creek, the most urbanized of the subbasins had 

the highest concentrations of chloride. Northrup 

Creek had the highest yields of nutrients of any of the 

sites, but these yields are influenced by sewagetreatment plant releases. 

Water quality management practices and 

improved treatment, or diversion, of sewage-treatment 

plant effluent continue to decrease the median 

concentration of some constituents (particularly 

nutrients) in surface water throughout Monroe County. 

Although the 1997-99 loads of most constituents 

delivered to Irondequoit Bay, were greater than during 

previous periods, the concentrations of those 

constituents during 1997-99 were lower.

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for Great Lakes rainbow trout: Journal of Fisheries 

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Brown, L.C. and Johnson, J.W., 1996, Nitrogen and the 

Hydrologic Cycle: Ohio State University Fact Sheet, 

AEX-463-96, 6 p.

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concentrations, mixing patterns, and stratification 

characteristics of Irondequoit Bay, Monroe County, 

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1974-84: U.S. Geological Survey Water-Resources 

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and smoothing scatterplots: Journal of the American 

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Summers, R.M., 1992, The validity of a simple 

statistical model for estimating fluvial constituent 

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Effects of a cattail wetland on water quality of 

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Report 00-4032, 74 p.

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Resources of Monroe County New York, Water Years 

1984-88, with emphasis on water quality in the 

Irondequoit Creek basin, part 2: U.S. Geological 

Survey Open-File Report 96-4054, 84 p.

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deposition, rainfall-runoff-quality modeling, and 

potential of wetlands for sediment and nutrient 

retention: U.S. Geological Survey Water-Resources 

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Kappel, W.M. and Young, R.A., 1989, Glacial history and 

geohydrology of the Irondequoit Creek valley, Monroe 

County, New York: U.S. Geological Survey WaterResources Investigations Report 88-4145, 34 p.

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derive water-quality trends for use by the national 

water summary program of the U.S. Geological 

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1990, Chemical analysis and nutrient loading of 

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Sewage Treatment Plant, Precipitation falling in 

Western Monroe County, with a discussion on the 

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N.Y., State University of New York at Brockport, 

unpublished report, 120 p.

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on Kendall’s tau: Journal of the American Statistical 

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water quality in the Irondequoit Creek basin, part 2: 

U.S. Geological Survey Water-Resources 

Investigations Report 99-4084, 50 p.

Sherwood, D.A., 2001, Water Resources of Monroe County 

New York, Water Years 1994-96, with emphasis on 

water quality in the Irondequoit Creek basin: U.S. 

Geological Survey Water-Resources Investigations 

Report 00-4201, 44 p.

Sherwood, D.A., 2001, Effects of a Vegetated StormwaterDetention Basin on Chemical Quality and Temperature 

of Runoff from a Small Residential Development in 

Monroe County, New York: U.S. Geological Survey 

Water-Resources Investigations Report 01-4099, 11 p.

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New York streams by river basins—a stream gazetteer: 

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Rochester, New York: U.S. Geological Survey WaterResources Investigations Report 84-4259, 6 pl.

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ground-water sampling program (1988-93), 

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Park-Browncroft Boulevard reach: Rochester, N.Y., 

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report, 20 p.

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References Cited
46 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin
Appendix 47

APPENDIX

Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit 

Creek basin and at four sites in western Monroe County, N.Y., water years 1997-99

Irondequoit Creek basin:

Irondequoit Creek at Railroad Mills (1997-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

East Branch Allen Creek at Pittsford (1997-99). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Allen Creek near Rochester (1997-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Irondequoit Creek at Blossom Road (1997-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Western Monroe County:

Northrup Creek at North Greece (1997-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Oatka Creek at Garbutt (1997-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Honeoye Creek at Honeoye Falls (1998-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Black Creek at Churchville (1998-99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
48 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Appendix. Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin and at four 

sites in western Monroe County, N.Y., water years 1997-99.

[Loads are in tons. Error when multiplied by 1.96 and added to or subtracted from the estimated load, provides the 95-percent confidence limits of the 

load estimate. Dashes indicate no data. Locations are shown in figure.]

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Irondequoit Creek at Railroad Mills (04232034)

Water year 1997

OCT 412 343 49.0 30.8 0.067 0.026 3.17 1.08 3.77 0.33 0.80 0.40 0.066 0.013 295 21 672 45

NOV 763 492 82.1 38.7 0.144 0.062 2.87 1.09 3.88 0.46 0.66 0.28 0.058 0.010 360 23 636 39

DEC 854 512 92.2 41.0 0.196 0.092 3.50 1.27 5.55 0.64 0.69 0.23 0.060 0.008 454 26 700 40

JAN 216 118 30.8 12.9 0.034 0.010 1.50 0.39 4.12 0.31 0.19 0.05 0.020 0.002 249 14 467 27

FEB 304 214 36.2 19.6 0.042 0.015 1.87 0.57 5.44 0.48 0.30 0.10 0.028 0.004 311 18 519 32

MAR 480 283 55.6 26.2 0.095 0.030 2.46 0.70 7.16 0.62 0.38 0.09 0.028 0.003 498 26 740 42

APR 210 127 32.3 15.5 0.061 0.017 1.59 0.39 4.54 0.34 0.20 0.05 0.012 0.001 337 18 605 34

MAY 194 113 34.2 15.3 0.053 0.016 1.80 0.52 3.85 0.35 0.31 0.10 0.014 0.002 230 13 561 34

JUN 454 232 58.3 23.5 0.088 0.025 1.98 0.56 3.86 0.35 0.56 0.16 0.026 0.003 197 12 520 32

JUL 262 176 31.5 17.3 0.037 0.013 0.51 0.17 2.03 0.20 0.19 0.06 0.013 0.002 101 7 320 24

AUG 110 73 15.9 8.7 0.010 0.003 0.36 0.12 1.63 0.14 0.10 0.03 0.009 0.001 90 6 318 22

SEP 100 81 17.1 10.7 0.006 0.002 0.77 0.24 1.80 0.14 0.15 0.06 0.015 0.002 119 8 405 26.

Total 4359 2764 535.2 260.2 0.833 0.311 22.38 7.10 47.63 4.36 4.53 1.61 0.349 0.051 3241 192 6463 397

Water year 1998

OCT 186 134 31.2 18.4 0.009 0.004 0.76 0.22 1.68 0.13 0.12 0.03 0.017 0.002 141 9 413 27

NOV 871 542 104.3 52.1 0.067 0.027 1.76 0.65 2.76 0.34 0.34 0.09 0.039 0.005 284 17 530 33

DEC 738 433 95.1 45.2 0.066 0.025 1.80 0.60 3.57 0.40 0.29 0.07 0.033 0.004 315 18 534 30

JAN 1694 1147 183.2 87.4 0.167 0.063 5.65 1.51 8.96 0.65 1.98 1.06 0.164 0.036 561 35 849 50

FEB 941 560 102.6 47.2 0.054 0.015 2.85 0.69 6.84 0.49 0.56 0.16 0.054 0.006 428 24 663 36

MAR 1135 616 123.5 52.8 0.095 0.024 2.87 0.66 7.31 0.52 0.55 0.14 0.045 0.005 551 29 793 42

APR 353 218 55.5 27.7 0.045 0.010 1.42 0.28 3.90 0.24 0.20 0.05 0.014 0.001 317 17 574 30

MAY 224 135 43.7 20.9 0.026 0.007 1.09 0.30 2.68 0.23 0.19 0.05 0.011 0.001 177 11 453 27

JUN 791 495 92.1 39.0 0.062 0.019 1.35 0.38 2.80 0.24 0.54 0.21 0.028 0.004 153 10 425 27

JUL 2603 1782 205.3 97.7 0.198 0.078 2.77 0.94 4.55 0.41 2.01 0.92 0.092 0.017 253 18 598 40

AUG 369 207 45.7 20.3 0.014 0.004 0.60 0.16 2.03 0.14 0.20 0.05 0.018 0.002 125 8 400 24

SEP 176 121 31.0 17.6 0.004 0.002 0.64 0.15 1.69 0.11 0.14 0.03 0.016 0.002 120 7 416 25

Total 10081 6390 1113.2 526.3 0.807 0.278 23.56 6.54 48.77 3.90 7.12 2.86 0.531 0.085 3425 203 6648 391

Water year 1999

OCT 295 235 51.7 34.3 0.006 0.003 0.68 0.21 1.48 0.13 0.13 0.04 0.019 0.003 136 9 400 28

NOV 454 415 73.1 55.5 0.016 0.007 0.51 0.21 1.30 0.17 0.10 0.03 0.016 0.002 143 11 322 25

DEC 402 348 67.3 48.3 0.017 0.007 0.54 0.19 1.64 0.20 0.09 0.03 0.014 0.002 155 10 315 22

JAN 1066 899 127.2 72.6 0.033 0.013 2.02 0.64 4.01 0.31 0.61 0.35 0.062 0.014 266 18 466 30

FEB 1016 601 124.3 58.5 0.022 0.006 1.73 0.39 4.56 0.31 0.33 0.09 0.040 0.005 310 17 522 31

MAR 2006 1264 217.8 108.5 0.080 0.019 2.64 0.58 6.38 0.43 0.62 0.18 0.053 0.006 530 29 759 43

APR 671 479 106.7 62.6 0.040 0.008 1.55 0.31 3.83 0.24 0.26 0.06 0.019 0.002 341 18 608 33

MAY 317 227 66.0 39.0 0.016 0.005 0.80 0.23 2.16 0.20 0.16 0.04 0.011 0.001 156 10 415 27

JUN 522 392 78.5 48.0 0.017 0.006 0.46 0.15 1.49 0.16 0.19 0.06 0.014 0.002 87 7 285 24

JUL 646 508 83.0 54.3 0.018 0.006 0.34 0.10 1.39 0.14 0.18 0.06 0.015 0.002 82 7 271 22

AUG 336 246 48.8 29.5 0.006 0.002 0.29 0.08 1.24 0.10 0.12 0.03 0.013 0.002 81 6 290 21

SEP 179 152 35.8 25.3 0.002 0.001 0.35 0.10 1.09 0.09 0.09 0.03 0.013 0.002 83 6 315 23

Total 7910 5766 1080.2 636.4 0.273 0.083 11.91 3.19 30.57 2.48 2.88 1.00 0.289 0.043 2370 148 4968 329
Appendix 49

East Branch Allen Creek at Pittsford (0423204920)

Water year 1997

OCT 303 182 36.7 18.8 0.025 0.010 1.04 0.18 1.56 0.28 0.51 0.13 0.091 0.030 93 10 92 10

NOV 156 84 23.0 10.5 0.027 0.012 0.94 0.17 1.67 0.32 0.32 0.07 0.060 0.017 115 11 84 8

DEC 107 57 18.6 8.5 0.040 0.017 1.02 0.19 2.01 0.39 0.23 0.05 0.041 0.011 193 18 89 8

JAN 34 16 6.6 2.7 0.021 0.007 0.34 0.05 0.87 0.13 0.05 0.01 0.008 0.002 122 11 43 3

FEB 60 35 9.4 4.8 0.022 0.008 0.46 0.07 2.61 0.45 0.08 0.02 0.013 0.003 181 18 50 4

MAR 68 37 10.1 5.0 0.024 0.008 0.77 0.12 4.47 0.70 0.12 0.02 0.016 0.003 250 21 83 7

APR 18 10 2.8 1.4 0.010 0.003 0.29 0.04 0.90 0.15 0.04 0.01 0.003 0.001 82 8 43 3

MAY 26 14 4.3 2.0 0.020 0.007 0.30 0.04 0.37 0.06 0.05 0.01 0.004 0.001 52 5 43 4

JUN 34 13 5.4 1.9 0.020 0.006 0.23 0.03 0.38 0.05 0.07 0.01 0.008 0.001 35 3 41 3

JUL 20 9 3.1 1.3 0.008 0.003 0.11 0.02 0.26 0.04 0.05 0.01 0.008 0.002 19 2 33 3

AUG 32 19 4.4 2.3 0.005 0.002 0.13 0.02 0.24 0.04 0.05 0.01 0.010 0.002 20 2 41 3

SEP 77 50 10.2 5.6 0.006 0.002 0.21 0.03 0.25 0.04 0.07 0.02 0.015 0.004 27 3 46 4

Total 935 526 134.6 64.8 0.228 0.085 5.84 0.96 15.59 2.65 1.64 0.37 0.277 0.077 1189 112 688 60

Water year 1998

OCT 59 26 9.7 3.8 0.008 0.003 0.24 0.03 0.29 0.04 0.06 0.01 0.013 0.003 34 3 46 4

NOV 63 29 11.7 4.9 0.016 0.006 0.42 0.06 0.61 0.10 0.08 0.01 0.019 0.004 70 6 58 5

DEC 35 17 7.7 3.4 0.021 0.008 0.36 0.05 0.59 0.09 0.05 0.01 0.010 0.002 100 8 51 4

JAN 395 265 58.0 32.1 0.118 0.055 1.87 0.34 3.84 0.68 0.66 0.23 0.110 0.046 382 42 108 11

FEB 128 63 20.1 8.9 0.037 0.012 0.72 0.09 3.51 0.48 0.12 0.02 0.023 0.005 264 23 72 6

MAR 111 55 16.4 7.4 0.032 0.010 0.89 0.11 4.23 0.56 0.14 0.02 0.021 0.004 270 22 90 7

APR 14 7 2.5 1.1 0.009 0.003 0.20 0.02 0.46 0.06 0.02 0.00 0.002 0.000 61 5 36 2

MAY 13 6 2.4 1.1 0.013 0.004 0.14 0.02 0.13 0.02 0.02 0.00 0.002 0.000 28 2 27 2

JUN 78 40 11.1 4.8 0.027 0.009 0.30 0.04 0.47 0.08 0.11 0.02 0.017 0.005 37 4 45 4

JUL 461 290 48.4 25.8 0.060 0.029 1.02 0.20 1.99 0.42 0.89 0.25 0.160 0.057 75 9 91 10

AUG 114 67 14.0 7.2 0.009 0.003 0.27 0.04 0.40 0.06 0.10 0.02 0.026 0.006 31 3 58 5

SEP 106 48 15.4 6.4 0.008 0.002 0.25 0.03 0.25 0.03 0.07 0.01 0.017 0.003 34 3 60 5

Total 1577 913 217.4 106.9 0.358 0.144 6.68 1.03 16.77 2.62 2.32 0.60 0.420 0.135 1386 130 742 65

Water year 1999

OCT 28 17 4.9 2.6 0.004 0.001 0.09 0.01 0.08 0.01 0.02 0.00 0.005 0.001 16 2 26 2

NOV 4 3 1.2 0.8 0.004 0.001 0.05 0.01 0.05 0.01 0.01 0.00 0.002 0.000 13 1 15 1

DEC 7 4 1.7 1.1 0.007 0.003 0.08 0.01 0.09 0.02 0.01 0.00 0.002 0.000 28 3 18 1

JAN 214 163 32.8 20.9 0.057 0.027 0.76 0.14 1.72 0.34 0.18 0.06 0.038 0.016 195 25 55 6

FEB 84 43 15.2 7.1 0.028 0.009 0.41 0.05 1.43 0.18 0.05 0.01 0.012 0.002 169 16 51 4

MAR 150 81 22.2 10.8 0.038 0.012 0.95 0.12 3.54 0.47 0.15 0.02 0.024 0.005 260 23 91 8

APR 26 14 4.7 2.4 0.014 0.004 0.29 0.03 0.47 0.06 0.03 0.00 0.003 0.001 73 6 44 3

MAY 26 15 4.8 2.6 0.019 0.006 0.22 0.03 0.18 0.03 0.03 0.00 0.003 0.001 38 4 36 3

JUN 33 16 5.9 2.6 0.019 0.006 0.15 0.02 0.16 0.02 0.04 0.01 0.006 0.001 24 2 32 3

JUL 34 16 5.7 2.5 0.011 0.003 0.12 0.02 0.18 0.03 0.04 0.01 0.010 0.002 18 2 33 3

AUG 39 25 5.8 3.3 0.005 0.002 0.10 0.01 0.12 0.02 0.03 0.01 0.009 0.002 15 1 34 3

SEP 45 27 7.3 4.0 0.004 0.002 0.10 0.01 0.08 0.01 0.03 0.00 0.007 0.001 15 2 33 3

Total 690 424 112.2 60.7 0.210 0.076 3.32 0.46 8.10 1.20 0.62 0.12 0.121 0.032 864 87 468 40

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
50 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Allen Creek near Rochester (04232050)

Water year 1997

OCT 295 221 66.2 38.2 0.070 0.026 2.45 0.69 2.88 0.47 0.73 0.26 0.160 0.039 307 44 145 10

NOV 120 87 24.2 13.8 0.043 0.014 1.76 0.52 2.52 0.43 0.30 0.08 0.090 0.016 368 43 134 8

DEC 250 172 38.0 21.1 0.064 0.022 2.77 0.78 4.50 0.74 0.42 0.11 0.096 0.019 788 88 195 11

JAN 103 59 15.7 6.7 0.032 0.009 1.28 0.30 2.15 0.28 0.10 0.02 0.019 0.003 531 57 90 5

FEB 222 164 29.8 16.8 0.053 0.016 2.21 0.64 3.86 0.62 0.19 0.05 0.027 0.005 745 92 116 7

MAR 253 170 33.6 18.5 0.066 0.019 3.19 0.79 5.94 0.83 0.25 0.04 0.026 0.003 1078 113 203 11

APR 78 47 12.7 6.0 0.030 0.008 1.27 0.28 2.32 0.29 0.09 0.02 0.008 0.001 481 52 116 6

MAY 62 40 14.2 6.7 0.035 0.010 1.01 0.24 1.40 0.19 0.10 0.02 0.010 0.001 253 29 84 5

JUN 93 51 19.9 8.3 0.047 0.014 1.23 0.30 1.36 0.19 0.18 0.03 0.029 0.004 182 21 78 4

JUL 54 39 8.9 4.6 0.023 0.008 0.52 0.16 0.65 0.11 0.14 0.03 0.025 0.004 87 11 46 3

AUG 168 139 20.2 11.9 0.018 0.005 0.59 0.18 0.66 0.10 0.18 0.05 0.021 0.004 97 13 56 4

SEP 233 194 41.1 25.6 0.026 0.009 0.92 0.26 1.00 0.15 0.27 0.09 0.041 0.010 137 19 79 5

Total 1931 1383 324.5 178.2 0.507 0.160 19.20 5.14 29.24 4.40 2.95 0.80 0.552 0.109 5054 582 1342 79

Water year 1998

OCT 52 33 12.3 5.7 0.018 0.005 0.56 0.13 0.75 0.10 0.11 0.02 0.032 0.005 121 14 64 3

NOV 86 61 16.2 9.4 0.030 0.008 1.11 0.30 1.80 0.29 0.19 0.04 0.064 0.009 303 34 121 7

DEC 112 77 16.1 9.0 0.031 0.008 1.21 0.28 2.23 0.31 0.14 0.02 0.037 0.005 503 52 130 7

JAN 1410 938 168.9 92.1 0.242 0.115 5.02 1.21 11.41 1.99 2.24 1.07 0.317 0.108 1687 244 330 26

FEB 476 321 54.6 29.4 0.076 0.020 3.01 0.72 5.68 0.77 0.32 0.07 0.047 0.007 1058 117 185 10

MAR 471 342 52.8 31.3 0.085 0.023 3.35 0.71 7.14 0.88 0.40 0.08 0.044 0.007 1221 128 257 14

APR 59 41 8.9 4.8 0.021 0.005 0.72 0.14 1.53 0.17 0.07 0.01 0.006 0.001 347 36 95 5

MAY 70 55 13.0 7.0 0.028 0.007 0.68 0.16 1.12 0.15 0.08 0.02 0.009 0.001 211 25 77 4

JUN 481 334 62.1 31.8 0.073 0.026 1.71 0.49 2.01 0.33 0.54 0.17 0.084 0.019 210 28 107 7

JUL 2185 1308 244.4 115.4 0.234 0.101 4.61 1.36 5.97 1.09 3.68 1.31 0.492 0.126 448 64 264 19

AUG 1328 933 126.3 68.2 0.054 0.018 1.74 0.46 2.04 0.30 0.94 0.32 0.098 0.023 234 32 153 10

SEP 464 259 62.1 25.1 0.029 0.007 1.07 0.23 1.19 0.14 0.31 0.06 0.045 0.006 177 20 115 6

Total 7194 4702 837.7 429.2 0.921 0.343 24.79 6.19 42.87 6.52 9.02 3.19 1.275 0.317 6520 794 1898 118

Water year 1999

OCT 91 65 18.3 9.3 0.020 0.005 0.56 0.14 0.81 0.11 0.14 0.03 0.040 0.006 135 15 81 4

NOV 10 9 2.4 1.7 0.010 0.003 0.21 0.06 0.49 0.09 0.05 0.01 0.021 0.003 108 14 49 3

DEC 21 22 3.0 2.3 0.010 0.003 0.22 0.06 0.58 0.09 0.04 0.01 0.012 0.002 164 22 48 3

JAN 913 778 90.4 60.5 0.096 0.043 2.11 0.64 5.02 0.95 0.69 0.30 0.105 0.032 823 142 166 14

FEB 317 221 33.6 18.8 0.043 0.011 1.51 0.35 3.11 0.40 0.16 0.03 0.030 0.005 684 81 131 8

MAR 490 406 49.3 33.6 0.075 0.021 2.52 0.51 6.24 0.76 0.41 0.10 0.045 0.007 1092 124 261 15

APR 104 75 13.5 7.8 0.024 0.006 0.77 0.14 1.75 0.18 0.09 0.02 0.008 0.001 392 42 122 6

MAY 87 55 14.8 7.2 0.028 0.007 0.63 0.14 1.10 0.14 0.09 0.02 0.010 0.002 216 25 90 5

JUN 75 41 13.0 5.5 0.029 0.008 0.52 0.12 0.79 0.10 0.12 0.02 0.024 0.003 120 14 65 4

JUL 47 27 7.4 3.4 0.018 0.006 0.31 0.08 0.50 0.07 0.12 0.02 0.025 0.004 75 10 49 3

AUG 305 202 29.6 14.0 0.019 0.005 0.52 0.12 0.72 0.09 0.21 0.05 0.030 0.005 113 14 82 5

SEP 366 212 46.3 20.2 0.021 0.006 0.64 0.15 0.84 0.11 0.23 0.05 0.037 0.006 134 16 99 6

Total 2826 2113 321.6 184.3 0.393 0.124 10.52 2.51 21.95 3.09 2.35 0.66 0.387 0.076 4056 519 1243 76

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
Appendix 51

Irondequoit Creek at Blossom Road (0423205010)

Water year 1997

OCT 6556 6293 642 492 0.158 0.078 15.01 3.34 12.45 0.62 6.51 2.71 0.296 0.049 1413 92 1717 134

NOV 1301 997 165 107 0.133 0.043 10.02 1.57 14.16 0.56 2.13 0.65 0.206 0.026 1699 91 1678 114

DEC 2038 1509 249 152 0.344 0.103 15.20 2.27 23.38 0.90 3.10 0.89 0.257 0.029 2689 140 1992 134

JAN 597 242 88 32 0.143 0.033 5.06 0.57 14.64 0.53 0.65 0.11 0.092 0.009 1767 87 1212 77

FEB 1712 887 175 74 0.146 0.042 7.76 1.08 17.50 0.69 1.31 0.31 0.101 0.011 2101 113 1245 85

MAR 2197 795 227 72 0.228 0.051 13.42 1.40 24.79 0.85 1.81 0.28 0.113 0.010 3071 147 1820 113

APR 810 333 104 36 0.165 0.037 7.33 0.82 13.59 0.49 0.80 0.13 0.053 0.005 1738 87 1374 87

MAY 757 367 113 47 0.148 0.036 5.65 0.69 9.26 0.34 0.93 0.20 0.070 0.007 1059 53 1200 77

JUN 1055 402 145 49 0.105 0.025 5.10 0.59 7.99 0.30 1.23 0.21 0.120 0.012 816 41 1042 67

JUL 725 297 90 33 0.044 0.010 2.21 0.25 4.38 0.16 0.57 0.09 0.076 0.008 478 24 690 45

AUG 796 374 107 44 0.039 0.010 1.99 0.26 3.99 0.16 0.53 0.11 0.071 0.008 474 25 726 48

SEP 1434 1093 193 116 0.054 0.020 3.67 0.74 5.23 0.24 1.34 0.51 0.125 0.020 644 39 1004 71

Total 19978 13589 2298 1255 1.707 0.488 92.42 13.58 151.36 5.84 20.91 6.20 1.580 0.194 17949 939 15700 1052

Water year 1998

OCT 359 169 59 60 0.035 0.008 2.35 0.27 4.80 0.17 0.47 0.08 0.086 0.009 654 32 1014 64

NOV 377 213 59 59 0.088 0.021 4.66 0.54 9.39 0.34 0.81 0.15 0.146 0.015 1239 62 1344 86

DEC 391 193 63 63 0.171 0.037 5.15 0.53 13.39 0.46 0.75 0.11 0.139 0.012 1724 83 1421 88

JAN 42121 39309 2649 2118 2.158 1.093 40.65 9.63 39.58 1.85 27.03 11.73 0.608 0.086 4370 268 2621 201

FEB 2951 1340 287 106 0.272 0.069 11.17 1.36 23.41 0.86 2.56 0.51 0.197 0.020 2854 144 1652 106

MAR 3489 1325 328 104 0.361 0.084 15.69 1.70 26.65 0.92 3.10 0.53 0.176 0.016 3402 162 2043 125

APR 621 222 83 26 0.174 0.038 5.56 0.59 11.33 0.39 0.72 0.12 0.057 0.005 1540 74 1301 80

MAY 552 233 84 31 0.151 0.036 4.10 0.49 7.51 0.27 0.74 0.14 0.065 0.006 927 46 1107 69

JUN 1737 1035 200 94 0.129 0.037 5.17 0.81 7.25 0.30 2.21 0.64 0.187 0.027 759 41 1005 66

JUL 15598 13852 1188 807 0.348 0.154 16.23 3.24 14.03 0.65 14.11 5.47 0.620 0.092 1336 81 1533 113

AUG 1929 1185 236 116 0.083 0.025 3.71 0.58 6.08 0.24 1.61 0.47 0.179 0.023 713 38 1013 66

SEP 856 349 131 46 0.054 0.013 2.57 0.29 4.98 0.18 0.82 0.15 0.133 0.013 651 32 1058 67

Total 70981 59425 5368 3631 4.024 1.615 117.01 20.03 168.4 6.63 54.93 20.10 2.593 0.324 20169 1063 17112 1131

Water year 1999

OCT 353 177 58 26 0.041 0.010 2.09 0.24 4.48 0.16 0.53 0.10 0.107 0.011 643 32 1039 66

NOV 102 59 17 10 0.044 0.010 1.39 0.15 4.08 0.15 0.22 0.03 0.059 0.006 627 32 835 55

DEC 121 64 20 11 0.087 0.020 1.57 0.18 5.64 0.21 0.23 0.04 0.057 0.006 840 43 844 56

JAN 6228 6271 488 392 0.526 0.272 10.08 2.42 16.09 0.84 5.33 2.40 0.248 0.042 1995 134 1349 105

FEB 1221 474 138 47 0.199 0.050 5.69 0.67 15.68 0.60 1.34 0.24 0.160 0.017 2069 108 1319 88

MAR 3712 1655 332 121 0.451 0.118 14.31 1.72 24.13 0.89 3.69 0.72 0.209 0.021 3245 164 2036 132

APR 694 250 92 30 0.236 0.054 5.66 0.61 11.60 0.41 0.95 0.15 0.080 0.007 1637 80 1421 90

MAY 563 205 86 29 0.192 0.043 4.01 0.43 7.74 0.28 0.89 0.14 0.093 0.009 993 49 1211 77

JUN 606 226 82 27 0.098 0.022 2.45 0.26 4.90 0.17 0.84 0.13 0.117 0.011 577 29 859 55

JUL 633 253 78 29 0.060 0.013 1.68 0.18 3.74 0.13 0.65 0.10 0.110 0.010 453 22 708 45

AUG 761 303 102 36 0.059 0.013 1.72 0.19 3.84 0.14 0.67 0.11 0.118 0.012 501 25 807 51

SEP 659 285 102 39 0.055 0.014 1.90 0.23 3.99 0.15 0.73 0.14 0.134 0.015 559 29 973 65

Total 15653 10222 1596 797 2.048 0.639 52.55 7.28 105.91 4.13 16.07 4.30 1.492 0.167 14139 747 13401 885

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
52 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Northrup Creek at North Greece (0422026250)

Water year 1997

OCT 220 125 33.4 12.7 0.059 0.014 1.82 0.32 2.68 0.24 0.99 0.33 0.285 0.053 122 11 106 8

NOV 51 34 12.0 6.3 0.173 0.032 1.71 0.19 2.58 0.16 0.32 0.06 0.111 0.012 162 10 108 6

DEC 25 25 7.3 5.6 0.487 0.087 1.85 0.20 2.90 0.18 0.25 0.04 0.082 0.009 226 14 107 5

JAN 94 64 14.2 7.6 0.692 0.126 1.62 0.17 2.53 0.15 0.22 0.03 0.075 0.007 210 13 75 3

FEB 269 110 28.0 8.3 0.774 0.147 2.28 0.26 2.93 0.18 0.30 0.05 0.066 0.007 259 17 84 4

MAR 122 55 16.3 5.5 0.441 0.076 2.09 0.20 2.92 0.16 0.20 0.03 0.032 0.003 273 16 85 4

APR 28 12 5.3 1.7 0.083 0.017 0.83 0.09 1.58 0.09 0.10 0.01 0.021 0.002 118 8 40 2

MAY 41 18 8.0 2.5 0.025 0.005 0.73 0.08 1.33 0.09 0.22 0.03 0.074 0.008 63 4 34 2

JUN 50 20 8.7 2.7 0.020 0.004 0.73 0.08 1.19 0.07 0.30 0.04 0.119 0.012 45 3 34 1

JUL 16 8 2.7 1.0 0.007 0.001 0.29 0.03 0.70 0.05 0.15 0.02 0.066 0.008 19 1 19 1

AUG 37 14 5.3 1.5 0.006 0.001 0.28 0.03 0.77 0.05 0.17 0.02 0.065 0.007 24 2 25 1

SEP 119 51 15.5 4.8 0.008 0.002 0.37 0.05 0.93 0.06 0.23 0.04 0.107 0.012 32 2 35 2

Total 1072 536 156.7 60.2 2.775 0.512 14.60 1.70 23.04 1.48 3.45 0.70 1.103 0.140 1553 101 752 39

Water year 1998

OCT 48 25 8.3 3.3 0.011 0.002 0.33 0.04 0.87 0.06 0.12 0.02 0.081 0.009 32 2 31 1

NOV 43 35 11.3 7.4 0.165 0.032 1.31 0.13 2.16 0.13 0.22 0.03 0.087 0.008 141 9 103 5

DEC 40 42 10.8 8.9 0.496 0.087 1.68 0.16 2.78 0.16 0.23 0.03 0.081 0.007 223 13 118 5

JAN 501 321 59.9 28.5 1.171 0.228 3.77 0.60 5.15 0.45 1.14 0.41 0.245 0.050 402 31 177 12

FEB 462 184 43.7 12.5 0.700 0.127 2.10 0.22 2.82 0.17 0.29 0.05 0.068 0.007 248 15 94 4

MAR 221 105 25.9 8.9 0.390 0.069 1.92 0.19 2.80 0.16 0.22 0.03 0.036 0.003 254 15 93 4

APR 51 19 9.1 2.6 0.072 0.012 0.81 0.08 1.59 0.09 0.12 0.02 0.025 0.002 117 7 47 2

MAY 118 40 20.3 4.9 0.044 0.008 1.10 0.12 1.82 0.11 0.33 0.05 0.095 0.009 102 7 59 3

JUN 100 31 15.6 3.6 0.021 0.004 0.75 0.07 1.23 0.07 0.34 0.04 0.135 0.013 47 3 44 2

JUL 138 44 18.7 4.2 0.024 0.005 0.88 0.10 1.35 0.08 0.44 0.07 0.132 0.014 51 3 61 3

AUG 154 59 18.4 4.8 0.011 0.002 0.47 0.05 1.07 0.07 0.31 0.05 0.096 0.010 39 3 48 2

SEP 217 83 26.4 7.6 0.008 0.002 0.39 0.04 0.99 0.06 0.26 0.04 0.119 0.012 36 2 45 2

Total 2093 988 268.4 97.2 3.113 0.578 15.51 1.80 24.63 1.61 4.02 0.84 1.200 0.144 1692 110 920 45

Water year 1999

OCT 110 63 17.3 7.6 0.013 0.003 0.38 0.04 0.96 0.06 0.15 0.02 0.097 0.010 37 3 43 2

NOV 14 13 3.6 2.6 0.022 0.005 0.28 0.03 0.80 0.06 0.06 0.01 0.040 0.005 34 3 31 2

DEC 3 4 1.1 1.0 0.033 0.009 0.17 0.03 0.71 0.07 0.03 0.01 0.026 0.004 30 3 18 1

JAN 280 197 29.1 15.0 0.347 0.091 0.96 0.15 1.69 0.13 0.19 0.04 0.067 0.009 123 10 58 4

FEB 300 158 29.3 11.6 0.335 0.070 0.92 0.11 1.59 0.10 0.13 0.02 0.042 0.005 126 9 55 3

MAR 379 203 41.8 16.6 0.372 0.069 1.91 0.20 2.87 0.17 0.24 0.04 0.039 0.004 260 16 111 5

APR 75 34 12.5 4.2 0.059 0.011 0.69 0.07 1.44 0.08 0.11 0.01 0.025 0.002 104 6 48 2

MAY 190 62 30.3 7.3 0.037 0.007 0.98 0.10 1.70 0.11 0.32 0.04 0.100 0.010 93 6 64 3

JUN 191 62 27.1 6.6 0.021 0.004 0.77 0.08 1.27 0.08 0.37 0.05 0.151 0.015 49 3 53 2

JUL 155 54 20.3 5.3 0.016 0.003 0.61 0.06 1.12 0.07 0.32 0.04 0.113 0.012 40 3 55 3

AUG 246 95 28.4 8.1 0.011 0.002 0.47 0.05 1.09 0.07 0.32 0.05 0.104 0.011 41 3 59 3

SEP 483 230 54.2 19.5 0.010 0.002 0.46 0.05 1.13 0.08 0.33 0.05 0.146 0.016 43 3 63 3

Total 2426 1175 295.0 105.4 1.276 0.276 8.60 0.97 16.37 1.08 2.57 0.38 0.950 0.103 980 68 658 33

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
Appendix 53

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Oatka Creek at Garbutt (04230500)

Water year 1997

OCT -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

NOV -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

DEC -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

JAN -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

FEB -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

MAR -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

APR -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

MAY -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

JUN -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

JUL 91 30 34.4 15.0 0.072 0.011 1.78 0.20 7.42 0.25 0.18 0.02 0.033 0.004 221 6 1694 71

AUG 48 16 14.9 6.6 0.035 0.005 1.06 0.11 4.67 0.15 0.09 0.01 0.017 0.002 176 5 1466 77

SEP 65 25 19.3 8.8 0.026 0.005 1.20 0.17 5.09 0.20 0.12 0.02 0.026 0.006 197 6 1506 92

Total 204 71 68.6 30.4 0.133 0.021 4.04 0.48 17.18 0.60 0.39 0.05 0.076 0.012 594 17 4666 240

Water year 1998

OCT 151 46 67.7 26.0 0.045 0.008 2.5 0.31 9.46 0.34 0.27 0.04 0.068 0.010 330 9 1913 160

NOV 1283 451 613.5 287.0 0.290 0.054 12.49 1.65 35.12 1.35 1.78 0.27 0.469 0.076 930 29 2868 163

DEC 1713 548 564.3 247.8 0.764 0.123 15.95 1.86 54.18 1.89 2.25 0.30 0.614 0.086 1286 37 3252 189

JAN 8434 4333 1080 564.0 5.071 1.599 54.32 12.13 145.5 7.36 11.75 3.35 3.738 1.118 2487 95 4564 265

FEB 622 189 168.7 65.5 1.152 0.180 13.31 1.59 71.00 2.47 1.70 0.24 0.568 0.083 1304 37 3370 172

MAR 903 314 289.1 123.4 1.313 0.219 22.91 2.91 99.90 3.57 2.94 0.44 0.683 0.105 1895 55 4616 237

APR 394 103 121.2 38.9 0.439 0.065 10.80 1.21 48.59 1.60 1.16 0.15 0.182 0.025 1156 31 3660 179

MAY 685 208 124.2 38.5 0.447 0.083 11.69 1.67 39.49 1.52 1.57 0.28 0.244 0.046 930 28 3360 169

JUN 241 63 53.9 15.0 0.202 0.031 4.76 0.59 15.07 0.52 0.60 0.09 0.124 0.021 404 11 2174 105

JUL 2884 1424 378.9 182.5 0.916 0.286 25.45 5.84 40.70 2.21 6.07 1.79 1.296 0.404 834 32 2830 156

AUG 48 10 11.3 3.2 0.053 0.007 1.48 0.15 4.91 0.15 0.14 0.02 0.029 0.004 206 5 1470 68

SEP 26 5 6.4 2.0 0.028 0.004 0.96 0.10 3.43 0.10 0.08 0.01 0.020 0.002 171 4 1347 62

Total 17384 7694 3479.2 1593.8 10.72 2.659 176.62 30.01 567.35 23.08 30.31 6.98 8.035 1.980 11933 373 35424 1925

Water year 1999

OCT 24 5 10.7 3.1 0.026 0.004 0.99 0.11 3.33 0.11 0.08 0.01 0.024 0.003 176 5 1381 66

NOV 20 5 14.3 4.1 0.037 0.006 0.91 0.10 3.02 0.10 0.06 0.01 0.021 0.003 170 5 1244 64

DEC 27 7 11.8 3.8 0.093 0.015 1.07 0.12 4.31 0.15 0.08 0.01 0.026 0.004 214 6 1301 69

JAN 764 316 96.8 42.0 1.441 0.381 12.64 2.53 38.65 2.05 2.12 0.52 0.879 0.227 841 32 2215 121

FEB 355 93 70.4 21.8 1.195 0.200 11.34 1.42 49.02 1.81 1.39 0.20 0.578 0.088 1098 33 2866 155

MAR 251 75 72.0 26.8 0.783 0.134 12.21 1.60 47.57 1.77 1.34 0.21 0.355 0.058 1193 36 3354 178

APR 198 45 49.8 15.5 0.452 0.069 9.48 1.07 34.99 1.19 0.94 0.12 0.180 0.024 1016 28 3217 164

MAY 111 25 20.3 6.2 0.230 0.034 4.74 0.53 15.95 0.54 0.46 0.06 0.087 0.012 536 15 2441 122

JUN 29 6 6.3 1.9 0.100 0.015 1.58 0.17 4.80 0.16 0.14 0.02 0.033 0.004 199 5 1496 75

JUL 15 3 3.8 1.2 0.062 0.009 0.97 0.10 2.62 0.08 0.08 0.01 0.021 0.003 131 3 1186 58

AUG 8 2 1.6 0.6 0.031 0.005 0.58 0.06 1.63 0.05 0.04 0.00 0.011 0.001 103 3 1026 50

SEP 5 1 1.1 0.5 0.018 0.003 0.43 0.05 1.28 0.04 0.03 0.00 0.009 0.001 94 3 982 51

Total 1807 583 358.9 127.5 4.468 0.875 56.94 7.86 207.17 8.05 6.76 1.17 2.224 0.428 5771 174 22709 1173

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
54 Water Resources of Monroe County, New York, Water Years 1997-99, with Emphasis on Water Quality in the 

Irondequoit Creek Basin

Honeoye Creek at Honeoye Falls (04229500)

Water year 1998

OCT -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

NOV -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

DEC -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

JAN -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

FEB -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

MAR -- -- -- -- 0.196 0.044 14.61 1.85 34.45 12.70 2.47 0.33 0.565 0.073 1115 62 792 68

APR -- -- -- -- 0.173 0.032 8.32 0.88 3.60 1.00 1.27 0.15 0.222 0.023 554 25 443 31

MAY -- -- -- -- 0.131 0.023 4.57 0.51 1.45 0.45 0.89 0.12 0.177 0.022 269 12 211 15

JUN -- -- -- -- 0.019 0.003 0.66 0.07 0.27 0.07 0.10 0.01 0.030 0.003 44 2 32 2

JUL -- -- -- -- 0.089 0.020 5.34 0.73 3.66 1.43 1.41 0.24 0.299 0.046 186 11 153 13

AUG -- -- -- -- 0.005 0.001 0.25 0.03 0.07 0.02 0.03 0.00 0.009 0.001 14 1 14 1

SEP -- -- -- -- 0.003 0.001 0.15 0.02 0.03 0.01 0.02 0.00 0.007 0.001 11 1 13 1

Total -- -- -- -- 0.616 0.124 33.90 4.09 43.53 15.68 6.19 0.85 1.309 0.169 2193 114 1658 131

Water year 1999

OCT -- -- -- -- 0.003 0.001 0.19 0.02 0.02 0.01 0.02 0.00 0.008 0.001 19 1 21 1

NOV -- -- -- -- 0.007 0.002 0.29 0.03 0.02 0.01 0.03 0.00 0.008 0.001 32 2 30 2

DEC -- -- -- -- 0.021 0.004 0.50 0.06 0.06 0.02 0.07 0.01 0.012 0.001 56 3 45 3

JAN -- -- -- -- 0.148 0.045 4.85 0.95 13.80 7.67 1.59 0.40 0.257 0.058 400 31 252 29

FEB -- -- -- -- 0.109 0.022 3.61 0.44 11.41 3.65 0.65 0.09 0.118 0.016 432 23 274 22

MAR -- -- -- -- 0.233 0.048 9.19 1.13 11.73 3.86 1.48 0.21 0.174 0.022 805 42 546 43

APR -- -- -- -- 0.221 0.036 5.88 0.59 2.24 0.62 0.81 0.09 0.082 0.008 493 22 368 25

MAY -- -- -- -- 0.102 0.019 1.83 0.22 0.41 0.13 0.29 0.04 0.035 0.004 146 7 108 8

JUN -- -- -- -- 0.008 0.001 0.14 0.02 0.04 0.01 0.02 0.00 0.004 0.000 13 1 8 0

JUL -- -- -- -- 0.003 0.001 0.08 0.01 0.03 0.01 0.01 0.00 0.002 0.000 6 0 4 0

AUG -- -- -- -- 0.003 0.001 0.09 0.01 0.02 0.01 0.01 0.00 0.002 0.000 6 0 5 0

SEP -- -- -- -- 0.002 0.001 0.08 0.01 0.01 0.00 0.01 0.00 0.002 0.000 8 0 8 0

Total -- -- -- -- 0.860 0.181 26.73 3.49 39.79 16.00 4.99 0.84 0.704 0.111 2416 132 1669 133

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.
Appendix 55

Total

suspended solids

Volatile 

suspended solids

Ammonia 

nitrogen as 

N, dissolved

Ammonia + 

organic 

nitrogen as N, total

Nitrite + 

nitrate as N, 

total

Total 

phosphaous, as P

Orthophosphate as P, 

dissolved

Chloride, 

dissolved

Sulfate, 

dissolved

Month Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error Load Error

Black Creek at Churchville (04231000)

Water year 1998

OCT -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

NOV -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

DEC -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

JAN -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

FEB -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

MAR -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

APR -- -- -- -- 0.143 0.030 5.81 0.50 20.09 2.58 0.39 0.04 0.079 0.010 556 19 1716 104

MAY -- -- -- -- 0.280 0.058 7.63 0.74 16.21 2.38 0.80 0.11 0.154 0.025 509 18 1790 68

JUN -- -- -- -- 0.189 0.038 4.48 0.45 5.79 0.88 0.66 0.10 0.174 0.034 276 9 1142 75

JUL -- -- -- -- 0.154 0.033 5.48 0.52 6.75 0.98 0.86 0.12 0.237 0.038 312 11 1286 47

AUG -- -- -- -- 0.078 0.017 2.49 0.25 3.36 0.56 0.30 0.04 0.061 0.010 149 5 772 36

SEP -- -- -- -- 0.066 0.013 1.48 0.12 2.01 0.25 0.14 0.02 0.027 0.003 106 3 610 34

Total -- -- -- -- 0.910 0.189 27.37 2.58 54.21 7.63 3.15 0.43 0.732 0.120 1908 65 7316 364

Water year 1999

OCT -- -- -- -- 0.055 0.012 1.12 0.10 1.65 0.22 0.09 0.01 0.021 0.003 104 4 569 43

NOV -- -- -- -- 0.062 0.014 1.18 0.11 1.89 0.26 0.09 0.01 0.024 0.003 127 5 651 39

DEC -- -- -- -- 0.091 0.021 1.19 0.11 2.11 0.29 0.10 0.01 0.028 0.004 120 4 606 185

JAN -- -- -- -- 0.327 0.096 12.59 1.91 42.05 9.51 1.79 0.38 0.836 0.221 618 33 1593 135

FEB -- -- -- -- 0.319 0.074 11.27 1.09 41.12 5.90 1.24 0.17 0.400 0.062 761 28 2062 135

MAR -- -- -- -- 0.221 0.049 10.92 1.07 31.92 4.57 0.96 0.13 0.198 0.032 920 34 2407 152

APR -- -- -- -- 0.222 0.045 5.19 0.43 9.66 1.20 0.46 0.05 0.045 0.006 468 15 1744 102

MAY -- -- -- -- 0.249 0.050 2.61 0.22 2.58 0.33 0.31 0.04 0.026 0.003 209 7 1057 62

JUN -- -- -- -- 0.094 0.019 0.73 0.06 0.37 0.05 0.10 0.01 0.015 0.002 64 2 377 22

JUL -- -- -- -- 0.035 0.008 0.36 0.03 0.14 0.02 0.05 0.01 0.010 0.001 33 1 208 12

AUG -- -- -- -- 0.046 0.011 0.65 0.07 0.37 0.07 0.09 0.01 0.011 0.002 46 2 309 21

SEP -- -- -- -- 0.040 0.008 0.41 0.03 0.21 0.03 0.04 0.00 0.006 0.001 35 1 250 14

Total -- -- -- -- 1.761 0.407 48.22 5.24 134.07 22.45 5.32 0.83 1.620 0.340 3505 136 11833 922

Appendix. (continued) Estimated monthly loads and associated error for nine constituents at four sites in the Irondequoit Creek basin 

and at four sites in western Monroe County, N.Y., water years 1997-99.