U.S. Department of the Interior

U.S. Geological Survey

Water-Resources Investigations Report 03-4151

December 2004

Seasonal Variability and Effects of Stormflow on Concentrations 

of Pesticides and their Degradates in Kisco River and Middle 

Branch Croton River Surface Water, Croton Reservoir System, 

New York, May 2000-February 2001

By Patrick J. Phillips, Robert W. Bode1

1

 New York State Department of Environmental Conservation

Samples from two streams in the Croton Reservoir system – Kisco River and the Middle Branch Croton River– were sampled 52 

and 31 times, respectively, from May 2000 through February 2001. Samples from the Kisco River contained over 30 pesticides or 

pesticide degradates, and samples from Middle Branch Croton River contained over 20 pesticides or pesticide degradates. Many of 

the pesticides detected most commonly in this study are generally used in developed areas, and are frequently used on turfgrass.
2

Seven herbicides (2,4-D, 2,4-D methyl 

ester, bromacil, dicamba, diuron, imazaquin, 

and sulfometuron), four insecticides (carbaryl, 

diazinon, imidacloprid, and malathion), two 

fungicides (metalaxyl and myclobutanil), 

and caffeine (an indicator of wastewater) 

were detected in at least one sample from 

the Kisco River at concentrations above 0.1 

μg/L (micrograms per liter). Four of these 

compounds – 2,4-D, 2,4-D methyl ester, 

dicamba, and metalaxyl – were detected in 

at least one sample from the Kisco River 

at a concentration above 1 μg/L. Only 

three herbicides (2,4-D, imazethapyr, and 

prometon) and caffeine were detected at 

concentrations above 0.1 μg/L in one or more 

of the Middle Branch Croton River samples, 

and no compounds were detected above 

0.4 μg/L in Middle Branch Croton River 

samples. No samples contained concentrations 

of pesticides that exceeded human healthbased water-quality standards. However, 

samples from the Kisco River contained four 

insecticides (carbaryl, chlorpyrifos, diazinon, 

and malathion) and one herbicide (2,4-D) in 

concentrations that exceeded water-quality 

criteria for the protection of aquatic life. 

Aquatic-life protection criteria were generally 

exceeded only in stormflow samples collected 

in June, September, and December 2000. No 

samples from the Middle Branch Croton River 

contained target compounds that exceeded 

water-quality criteria for the protection of 

aquatic life. 

Pesticide concentrations were generally 

higher, and the numbers of compounds 

generally larger in samples from the Kisco 

River than in samples from the Middle 

Branch Croton River, probably because 

the Kisco River watershed has a greater 

population density and is more extensively 

developed. The highest concentrations 

of most compounds in both streams were 

detected in stormflow samples collected in 

June, September, and December 2000. This 

indicates that stormflow sampling is essential 

in assessments of pesticide occurrence in 

streams that drain developed lands. The 

lowest concentrations of most compounds 

at both sites were detected in baseflow 

samples collected from October 2000 through 

February 2001, although the concentrations 

of several compounds increased substantially 

during stormflows at the Kisco River site in 

November and December, 2000. 

��� ������

���������

������

�����

�� ������

������

�

�� ��

�� ������

������ �����

�������

���������

DUTCHESS COUNTY

CONNECTICUT

NEW YORK

NY

CT

PUTNAM COUNTY

WESTCHESTER COUNTY

NEW YORK

Croton Basin

New York City

15'

7.5'

73o 52' 30" 45' 37' 30" 30'

41o 

30'

22'

30"

Base from U.S. Geological Survey digital data, 1:100,000, 1983

CARMEL

BEDFORD

MT KISCO

YORKTOWN

0

0 5 KILOMETERS

5 MILES

Sampling site

Basin outline 

State line

�����������

������

������ ������ �����

�

�� ��

� �� ��

Figure 1. Geographic features of Croton River basin, Westchester and Putnam Counties 

New York, and location of sampling sites. 
3

Introduction

The New Croton Reservoir in southeastern New York is 

directly north of New York City and provides about 10 percent 

of the city’s water supply. The 374-mi2 Croton River basin 

above the reservoir (fig. 1) is predominantly (69 percent) 

forested; about 14 percent is developed, and 17 percent is forest, 

wetland or water. The forested land in the watersheds of several 

streams that feed the reservoir is undergoing rapid development; 

therefore, concern has arisen as to whether pesticides used in 

these areas are entering these streams (Phillips and Bode, 2002). 

Past research on pesticides in surface waters of New York 

State has generally focused on streams that drain agricultural 

lands (Phillips and others, 1998; 1999; 2000; Eckhardt and 

Burke, 1999), but pesticides are also are used in a variety of 

settings in developed areas, such as on turfgrass, lawns and 

gardens, and golf courses; in buildings and parking lots; along 

roads, power-transmission right of ways, and railways; and in 

areas with ponded water for mosquito control. 

The types, rates, and timing (season) of application of 

pesticides used in developed areas differ from those used in 

agricultural areas, as do the pathways of pesticide migration to 

streams. For example, the chlorophenoxy herbicide compounds, 

including 2,4-D, which are used for weed control, are likely to 

be used more heavily in developed areas than in agricultural 

areas (Templeton and others, 1998). Although quantitative 

estimates of pesticide use in urban areas are generally 

unavailable, greater amounts are probably used (per acre) by 

homeowners than on the most commonly grown agricultural 

crops (Templeton and others, 1998). Pesticide applications in 

agricultural areas generally occur only in the spring, whereas 

those in developed areas occur throughout the growing season; 

some pesticides used in developed areas such as imazaquin, 

which is used for weed control on turfgrass, can also be applied 

after the first frost. Pesticide migration to streams in urban 

areas is generally more rapid and direct than in undeveloped 

and agricultural areas. The extensive impervious surfaces 

route pesticides washed by stormwater from lawns, ornamental 

plantings, and golf courses directly to storm drains and streams, 

whereas stormwater in undeveloped and agricultural areas 

generally infiltrates the soil, where its movement downwards to 

the water table or overland is retarded.

Previous Studies

Only a few studies have addressed the occurrence of 

pesticides in streams that drain developed areas or the factors 

that control their concentrations in these streams. A recent 

study of pesticide occurrence in eight streams draining small, 

developed watersheds throughout the United States (Hoffman 

and others, 2000) found that most samples contained at least one 

herbicide or insecticide and, unlike the samples from agricultural 

watersheds, contained higher total insecticide concentrations 

than total herbicide concentrations. A recent study of pesticides 

in base-flow samples from 47 streams within the Croton River 

basin in the summer of 2000 (Phillips and Bode, 2002) detected 

nine compounds at concentrations greater than 0.10 μg/L; three 

of these were insecticides (diazinon, carbaryl, and imidacloprid), 

one was a fungicide (myclobutanil), and five were herbicides 

(simazine, 2,4-D, diuron, hexazinone, and 2,4-D methyl esther). 

Only two of these compounds (simazine and 2,4-D) were 

detected at concentrations above 1 μg/L. That study probably 

did not detect the maximum pesticide concentrations, however, 

because it did not include stormflow samples, which reflect 

the wash-off of pesticides from lawns and other areas and thus 

contain elevated concentrations of these compounds. 

Few studies to date have examined instantaneous 

concentrations of commonly used pesticides in storm runoff 

from developed areas. Instantaneous-concentration data 

collected during storms provide an indication of the shortterm concentration increases to which aquatic life is exposed; 

these data also may help indicate the sources of pesticides or 

the processes that affect their movement. For example, field 

and modeling studies have indicated that little herbicide runoff 

occurs from well-maintained turf (Harrison and others, 1993). 

A study of 2,4-D, dicamba, and mecoprop in runoff from an 

experimental turfgrass plot, however, indicated that about 10 

percent of applied herbicide mass was transported from the plot, 

and that about 75 percent of the herbicide transport occurred 

during the first storm after application (Ma and others, 1999). 

An urban stream study in Minnesota by Wotzka and others 

(1998) indicated that event mean concentrations (EMC) of 

herbicides in streams that drain developed areas were as high as 

70 μg/L, and that triazine and acetanilide compounds (including 

atrazine and metolachlor), which are commonly associated with 

agriculture use, had lower EMCs than chlorophenoxy herbicides 

(including 2,4-D, MCPA, and MCPP). That study also found 

that maximum herbicide EMCs in developed areas occurred 

during midsummer storms, not those in spring or early-summer; 

in contrast, maximum EMCs in adjacent agricultural areas 

occurred during early spring storms (Wotzka and others, 1998). 

Approach and Objectives 

In 2000, the U.S. Geological Survey (USGS), in cooperation 

with the New York State Department of Environmental 

Conservation (NYSDEC), began a monitoring program to assess 

the occurrence of pesticides in surface waters of the Croton 

River basin. A part of that study entailed sampling at the mouths 

of two tributaries – the Kisco River and the Middle Branch 

Croton River (fig. 1 and table 1) – to identify which pesticides 

and pesticide degradates were present and to document the 

variability in their concentrations with respect to stream 

discharge and season. The objectives of the study were to (1) 

relate the presence of pesticides and their degradates in samples 

from the two sites to (a) the land-use characteristics (developed 

or agricultural) of the two watersheds and the inferred pesticideapplication times, and (b) Federal and State water-quality 

criteria; (2) evaluate and interpret temporal changes in pesticide 

concentrations in relation to seasons and flow (stormflow and 

baseflow) conditions. 
4

The two sites were chosen because their drainage areas 

contain forested, agricultural and developed land, but differing 

population densities, and because their developed lands reflect 

land use throughout the Croton River basin. The Kisco River 

watershed has a higher population density (940/mi2) and greater 

amount of developed land (23.8 percent) than the Middle Branch 

Croton River (hereafter referred to as Middle Branch) watershed 

(table 1) and thus, probably has greater pesticide use. The 

Middle Branch sampling site, 12 mi to the north of the Kisco 

River site, is 1.5 mi downstream from Lake Carmel, and Lake 

Carmel regulates flow at the Middle Branch site. 

This report (1) describes the study area, (2) presents the 

concentrations of all pesticides detected in stormflow and 

baseflow samples, (3) discusses the relations of pesticide 

occurrence and concentrations to land use and water quality 

standards, (4) explains the seasonal patterns of pesticide 

occurrence and concentrations, and (5) interprets the effect of 

stormflow on pesticide concentrations. 

Methods

Samples were collected from both sites (fig. 1, table 1) 

during base-flow and stormflow conditions from May 2000 

through February 2001; the stormflow samples were collected 

to discern whether stormflows produce the maximum pesticide 

concentrations. Stormflow samples were collected at the 

Kisco River site throughout the period of study; however, the 

largest storms sampled included storms in June, September, 

and December, 2000. These storms represent three of the four 

largest flows during the period May 2000 through February 

2001, and daily flows during these storms are exceeded less than 

10 percent of the time. Stormflow samples were also collected 

at Middle Branch during these three storms. Although the flow 

at the Middle Branch site is highly regulated, so the effect of 

rainfall on streamflow at this site is highly variable, the storms 

sampled include 2 of the three largest flows recorded at this site 

between May 2000 and February 2001.

Land-use characteristics of the watersheds above each 

sampling site were identified through satellite imagery collected 

in 1994 (U.S. Geological Survey, 1998: table 1). Population 

density data were obtained from 1990 census data (Bureau of the 

Census, 1991a,b). 

Sample Collection 

Baseflow samples and some stormflow samples were 

collected through standard equal-width interval (EWI) streamsampling techniques (Shelton, 1994). Most of the stormflow 

samples were collected as a point sample by an automatic 

sampler in glass bottles that had been cleaned according to 

procedures described in Shelton (1994). All tubing in the 

automatic sampler was Teflon2 lined, except for short (less than 

1-ft) sections in the pump head and distributor arm. The nonTeflon tubing sections were changed after every storm. The 

automatic samplers were programmed to collect samples after a 

prescribed rate of stage increase during the rising phase, near the 

peak, and during the falling stage of the stormflows. 

Analytical Methods and Quality Control

Samples were analyzed at the USGS National Water Quality 

Laboratory (NWQL) in Denver, Colo., by three analytical procedures: 1) the SH2010 method for 47 pesticides and degradates; 

(2) the SH2060 method for 63 pesticides and degradates; and 

(3) the SH2002 method for 76 pesticides and degradates. The 

SH2010 and SH2002 methods use gas chromatography/mass 

spectrometry and are described in Zaugg and others (1995) and 

Sandstrom and others (2001), respectively. The SH060 method 

uses liquid chromatography/mass spectrometry and is described 

in Furlong and others (2001). A complete list of analytes with 

method detection limits is given in reference cited above for 

each method. All methods use a 1-liter filtered sample extracted 

on a solid-phase cartridge; thus, the values represent filtered 

pesticide and pesticide-degradate concentrations. The detection 

limits provided by these methods range from 0.001 to nearly 

0.2 μg/L (micrograms per liter), which is much lower than that 

obtained by analytical methods typically used in public-watersupply-monitoring programs, and provide much higher rates 

of detection. Fifty-two samples were collected from the Kisco 

River site and analyzed by the SH2010 method, 25 samples from 

this site were analyzed by the SH2060 method, and 15 samples 

by the SH2002 method. Thirty-one samples were collected from 

�������. Drainage area, population, and land use represented by sampling sites on Middle 

Branch Croton River and Kisco River , N.Y., May 2000 through February 2001. 

���������������������������������������������������

��������������������������������������������������������������������������������������������������

�����������������������������������������������������������������������������������������������������������

������������������������������������������������������������������������������������������������

Site name

Drainage 

area

(mi2)

Population1

(per mi2) 

Percentage of watershed2

Developed Agricultural Forest

��������������������������� ���� ��� ���� ��� ����

��������������������������� ���� ��� ���� ��� ����

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. 
5

the Middle Branch site and analyzed by the SH2010 method, 16 

samples from this site were analyzed by the SH2060 method, 

and 8 samples by the SH2002 method. The constituents detected 

in samples from each site, and the methods used for each 

constituent, are summarized in tables 2A (Kisco River) and 2B 

(Middle Branch). 

Some of the concentrations reported for certain compounds 

analyzed by the SH2060 method (including some sufonylurea, 

imidazolinone, and sulfanomide herbicides), may reflect the 

tendency of the method to overestimate concentrations of some 

compounds by as much as a factor of 2 (Furlong and others, 

2001). Matrix enhancement may cause elevated recovery of 

such compounds as imazaquin, sulfometuron, imazethapyr, 

fluometuron, metalaxyl, and imidacloprid. The concentrations 

reported here are not adjusted for potential overestimation. The 

concentrations listed for some compounds in tables 2A and 

2B are indicated as estimated values for one of three reasons: 

because 1) they are reported below the detection limit, 2) they 

exceed the highest concentration on calibration curves, or 3) the 

compound has a high variability in reported method recoveries. 

Blank and replicate samples were collected for quality control 

samples. Blank samples were produced by exposing organicfree water supplied by the NWQL to sample intakes, pump-head 

tubing, and glass sample jars. No target analytes were detected 

in any of the 14 blanks (10 for SH2010, 2 for SH2060 and 2 for 

SH2002). Surrogate compounds added to the samples for the 

three analytical methods showed median recoveries of 74 to 104 

percent for all samples; 90 percent of the recoveries for most 

surrogates were between 64 and 124 percent. Concentrations of 

analytes were not adjusted for reported analytical recoveries. 

 Two duplicate samples were collected for each of the three 

analytical methods at the Kisco River site, and two duplicates 

for the SH2010 method were collected at the Middle Branch 

site. One duplicate pair consisted of a sample collected using 

the EWI technique that was divided into two aliquots, and the 

second duplicate pair consisted of a sample collected using the 

equal-width technique paired with a point sample collected 

concurrently by automatic sampler. These duplicate samples 

yielded 21 comparisons between analytes. Comparisons were 

made only if the same analyte was detected in both samples of a 

replicate pair. Concentration differences in these 21 comparisons 

ranged from 0 to 48 percent; the difference in 67 percent of these 

comparisons was less than 10 percent and exceeded 20 percent 

in only one comparison. Seven comparisons indicated a target 

compound in only one of the two samples paired for replicate 

analysis; the concentrations of the detected compound in all of 

these comparisons were near the detection limit. The comparison 

between samples collected by the EWI method with point 

samples collected by automatic sampler did not indicate any 

systematic bias in the latter samples; therefore, no correction was 

made to any point-sample concentrations. 

Concentrations of Pesticides and 

Selected Degradates

Of the more than 155 compounds for which the samples 

were analyzed, 38 were detected in samples collected from 

the Kisco River (table 2A), and 24 were detected in samples 

from the Middle Branch (table 2B). Of the 38 compounds 

detected in Kisco River samples, 25 were herbicide or herbicide 

degradates, 9 were insecticides or insecticide degradates, and 

3 were fungicides. Of the 24 compounds detected in Middle 

Branch samples, 17 were herbicides or herbicide degradates, 

5 were insecticides or insecticide degradates, and one was a 

defoliant. Caffeine (an indicator of wastewater) was detected in 

samples from both sites. The Kisco River samples contained four 

pesticides whose maximum concentrations exceeded 1 μg/L; the 

Middle Branch samples contained none.

The Kisco River samples contained 14 compounds at a 

concentration of 0.1 μg/L or greater in at least one sample 

(table 2A). Seven of these compounds are herbicides (2,4-D, 

2,4-D methyl ester, bromacil, dicamba, diuron, imazaquin, 

and sulfometuron), four are insecticides (carbaryl, diazinon, 

imidacloprid, and malathion), and two are fungicides (metalaxyl 

and myclobutanil). Caffeine was detected in at least one 

Kisco River sample at a concentration of 0.1 μg/L or greater. 

Four compounds (2,4-D, 2,4-D methyl ester, dicamba, and 

metalaxyl) were detected in at least one sample from this site at a 

concentration of 1.0 μg/L or greater. 

The Middle Branch samples contained only three herbicides 

(2,4-D, imazaquin, and prometon) at concentrations of 0.1 

μg/L or greater. Two of these (2,4-D and prometon) had 

maximum concentrations greater than 0.3 μg/L, but no pesticide 

or degradate had a concentration greater than 0.4 μg/L. The 

Middle Branch samples also contained two insecticides and 

three insecticide degradates, but at concentrations less than 0.1 

μg/L, and the defoliant, also at a concentration less than 0.1 

μg/L. Caffeine was detected in some Middle Branch samples at a 

concentration of 0.1 μg/L or greater. 

Together the two sites contained eight pesticide degradates 

– four were detected only in Kisco River samples, two only in 

Middle Branch samples, and two in samples from both sites 

(tables 2, 3). The maximum concentration of each of these 

compounds was less than 0.03 μg/L. The parent compounds 

of each degradate except 2,5-dichloraniline was detected in at 

least one sample from each site (table 2A, 2B). The presence 

of the 3,4-dichloroaniline, 1,4-napthoquinone, and 1-naphthol 

is difficult to interpret because these degradates can be formed 

through thermal degradation of the parent compound during 

analysis; therefore, it could have been either present in the 

sample initially, or created during the analysis.
6

��������� Data on pesticides detected in waters samples collected from Kisco River, N.Y., May 2000 - February 2001 

����������������������������������������������������������������������������������������������������������������������������������������

�����������������������������������������������������������������������������������������������������������������������������������������

������������������������������������������������������������������������������������������������������������

��������������

�������������������������������������������������������������������������������� ���������������������������������������������������������������������������������������������������������������������������������������

��������������������������������

���������������������������������������������������������������������������������������� ����������������������������������������������������������������������������������������������������������������������������

�����������������������������������������������������������������������������������������������������������������������������������

Compound

Analytical Method Percentage of samples

Water-quality

criterion 

(�g/L)

Maximum 

concentration

(�g/L)

Month of

maximum 

Type concentration

Detection 

limit

(�g/L)

With a 

compound 

detection�

Detected at 

concentration 

> 0.10 �g/L

�����������������������������������

����� ������ ����� �� �� �� ��� ���������

������������������ ������ ����� �� � �� ��� ���������

�������������������� ������ ����� �� � � ������� ����

�������� ������ ����� �� � ���� ����� ���

�������� ������ ����� � � �� ����� ��������

���������� ������ ����� � � �� ������ ��������

���������������� ������ ����� �� � � ������ ���

��������������������������� ������ ����� �� � � ����� ����

������� ������ ����� � � ���� ���� ���������

����������� ������ ����� �� � � ����� ��������

���������� ������ ����� �� � � ������ ��������

������ ������ ����� �� �� � ���� ���

����������� ������ ����� �� � � ������ ��������

���������� ������ ����� �� � � ����� ����

��������� ������ ���� �� �� ����� ��������

����������� ������ ����� � � � ������ ���

���� ������ ����� �� � ���� ����� ����

����������� ������ ����� ��� � ���� ����� ���

������������� ������ ����� ��� � � ����� ��������

�������� ������ ����� �� � � ����� ���������

������� ������ ����� �� � ����� ����

�������� ������ ����� �� � ���� ����� ���

������������ ������ ����� �� � � ���� ���

����������� ������ ����� ��� � ���� ������� ���������

����������� ������ ����� ��� � ���� ������� ��������

���������������������������������������

������������������ ������ ����� �� � � ������� ��������

����������� ������ ����� �� � � ����� ��������

����������������������������

������������������ ������ ����� �� � � ����� ����

�������� ������ ����� �� �� ���� ����� ��������

������������ ������ ����� ��� � ������ ���� ���������

�������� ������ ����� �� ��� ����� ���� ����

��������� ������ ����� �� � � ����� �����

�������������� ������ ����� �� � � ���� �����

��������� ������ ����� �� ��� ���� ���� ���������

�������������� ������ ���� � � � ������� ��������

����������

������� ������ ����� � � � ������ ������

��������� ������ ����� �� � � ���� ������

������������ ������ ����� �� ��� � ����� �����

�����

�������� ������ ����� �� �� � ����� ��������
7

��������� Data on pesticides detected in water samples collected from Middle Branch Croton River, May 2000 - February 2001

������������������������������������������������������������������������������������������������������������������������������������������������

�������������������������������������������������������������������������������������������������������������������������������

�����������������������������������������������������������������������������������������

�������������

������������������������������������������������������������������������������� ����������������������������������������������������������������������������������������������������������� �����������������������������������������������������������

��������������������������������������������������������������������������������������� ���������������������������������������������������������������������������������������������������������������������������

����������������������������������������������������������������������������������������������������������������������������������

Compound

Analytical Method Percentage of samples Waterquality

criterion 

(�g/L)

Maximum 

concentration

(�g/L)

Month of

maximum 

Type concentration

Detection 

limit

(�g/L)

With a

compound 

detection�

Detected at

concentration 

> 0.10 �g/L

�����������������������������������

����� ������ ����� �� �� ��� ����� ���

������������������ ������ ����� �� � � ������ ���

�������� ������ ����� �� � ���� ������ ���

�������� ������ ����� ��� � ��� ������ ����

���������������� ������ ����� �� � � ������� ���

��������������������������� ������ ���� �� � � ������ ����

�������������������� ������ ����� �� � � ������� ���

������� ������ ����� ��� � ������ ������ ���

���������� ������ ����� ��� � � ������ ��������

������ ������ ����� �� � � ������� ���������

����������� ������ ����� �� � � ������ ��������

��������� ������ ����� �� ��� � ����� ��������

����������� ������ ����� �� � � ������ ���

����������� ������ ����� �� � ��� � ������ ���

�������� ������ ����� �� ��� � ����� ����

�������� ������ ����� ��� � ��� � ������� ����

��������� ������ ����� �� � ������� ��������

���������������������������������������

������������������ ������ ����� �� � � ������� ��������

�������������������� ������ ����� �� � ������� ��������

��������������������������

������������������ ������ ����� �� � � ������ ����

�������� ������ ����� �� � ��� � ������ ��������

�������� ������ ����� �� � ������ ������ ����

���������

��������� ������ ����� �� � � ������� ��������

�����

�������� ������ ����� �� �� � ���� ���������
8

Effects of Land Use and Timing of Application 

on Pesticide Concentrations

The Kisco River samples generally contained pesticides in 

greater numbers and at higher concentrations than the Middle 

Branch samples because the Kisco River watershed has a 

higher population density and greater percentage of developed 

land (table 1). The concentrations of most of the commonly 

detected herbicides, including 2,4-D, diuron, 2,4-D methyl ester, 

dichlorprop, and imazaquin, exceeded 0.1 μg/L more frequently 

in samples from the Kisco River than in samples from Middle 

Branch (tables 2A, 2B) and had higher maximum concentrations. 

The only herbicide to be detected at a concentration greater 

than 0.1 μg/L more frequently in samples from Middle Branch 

than in samples from Kisco River was prometon (table 2A, 2B). 

Diazinon and carbaryl were detected in more than 70 percent 

of the samples from the Kisco River (table 2A), but in fewer 

than half of the samples from Middle Branch. The insecticides 

malathion and imidacloprid were detected in one or more 

samples from the Kisco River at concentrations greater than 0.1 

μg/L, but not in any samples from the Middle Branch. 

The interpretation that the higher detection frequency 

and higher maximum concentrations in the Kisco River 

samples than in the Middle Branch samples results from this 

watershed’s greater population density is supported by Hoffman 

and others (2000). Hoffman and others (2000) detected the 

insecticides carbaryl, diazinon, malathion, and chlorpyrifos 

more frequently in samples from urban streams than in nonurban 

streams throughout the United States, and also noted that peak 

insecticide yields could be expected in developed watersheds 

with population densities ranging from 2,600 to 4,000 per square 

mile. This interpretation is also consistent with a comparison of 

pesticide concentrations throughout the Croton River basin in 

the summer of 2000 (Phillips and Bode, 2002), who found the 

highest baseflow summer pesticide concentrations in watersheds 

with population densities greater than 1,000 per square mile. 

Little quantitative information on pesticide applications in 

developed areas is available from the literature, but some of 

the pesticides that can be expected to be used most commonly 

in developed areas were among those detected most frequently 

in this study. For example, the chlorophenoxy herbicides 

2,4-D, 2,4-D methyl ester and dichlorprop which are heavily 

used in developed areas (Templeton and others 1998), were 

frequently detected in samples from the Kisco River, as were 

the herbicides diuron and imazaquin, which also are used in a 

variety of developed settings, including lawns, golf courses, 

and rights of way (Pesticide Action Network, 2002). Diazinon 

and carbaryl, which are commonly used in developed areas for 

control of insects on turfgrass and in gardens, and malathion, 

which is used on ornamental plants and for mosquito control 

in developed areas (Hoffman and others, 2000), were among 

the most frequently detected compounds in Kisco River. The 

herbicide 2,4-D methyl ester, the insecticide imidacloprid, and 

the fungicide metalaxyl, which were not included in the national 

study by Hoffman and others (2000), were frequently detected 

at elevated concentrations in samples from the Kisco River; this 

indicates that they may also be present in other urban streams 

across the United States.

Pesticides that are associated with agricultural use, but not 

commonly used in urban areas, were detected infrequently in the 

Kisco River and Middle Branch samples. The herbicides atrazine 

and metolachlor, which are commonly used in agricultural 

settings, and the atrazine degradate 2-Chloro-4-isopropylamino6-amino-s-triazine (also known as deethylatrazine) are frequently 

found in urban streams at low concentrations (Hoffman and 

others, 2000). These compounds were not detected in the Kisco 

River and Middle Branch samples at concentrations above 0.1 

μg/L, and only rarely at concentrations above 0.01 μg/L. In 

contrast, these three compounds were detected at concentrations 

above 0.01 μg/L in nearly all samples collected during 1994-

96 from Canajoharie Creek, a central New York stream that 

drains an agricultural area. The concentrations of atrazine and 

�������. Pesticide degradates detected and their parent compounds detected in samples from Kisco River and Middle 

Branch Croton River, N.Y., 2000-2001.

�����������������������������������������������������������������������������������������������������������

�������������������������������������������������������������������������������������������������������

��������������������������������������

Common name Sample source Parent compound

Deethylatrazine Kisco River, Middle Branch Atrazine

Deethyldeisopropylatrazine Kisco River Atrazine

Deisopropylatrazine Middle Branch Simazine, Atrazine

3,4-Dichloroaniline* Kisco River Diuron, Propanil, Linuron, Neburon

1,4-Napthoquinone* Kisco River Carbaryl

1-Napthhol* Kisco River Carbaryl

2-[(2-ethyl-6methylphenyl)amino]-1-propanol Kisco River, Middle Branch Metolachlor

2,5-Dichloroaniline Middle Branch Chloramben
9

metolachlor commonly exceeded 0.1 μg/L during storms in 

June during the three year study at Canajoharie Creek. (Wall 

and Phillips, 1998). The national study by Hoffman and others 

(2000) concluded that the most likely source of these agricultural 

pesticides in streams that drain developed non-agricultural areas 

is atmospheric drift from nearby agricultural lands. Neither the 

Kisco River nor the Middle Branch watersheds contain much 

farmland; therefore, these three compounds are probably derived 

either from minor applications within these watersheds or from 

atmospheric drift from agricultural areas outside the watershed. 

Pesticide Concentrations in Relation to Established 

Water-Quality Standards and Guidelines

No compounds detected in this study exceeded any humanhealth-based water-quality standards, but four insecticides 

and one herbicide in samples from the Kisco River exceeded 

water-quality guidelines for the protection of aquatic life (fig. 

2, tables 2A, 2B). No pesticides in samples from the Middle 

Branch exceeded any water-quality criteria (fig. 2, tables 2A, 

2B). No health-based standards or aquatic-life-based waterquality guidelines have been established for at least half of the 

compounds detected in this study, however.

The insecticides diazinon, carbaryl, malathion, and 

chlorpyrifos were detected at least once in Kisco River samples 

at concentrations that exceeded an aquatic-life-protection 

guideline (fig. 2). Diazinon concentrations exceeded the aquaticlife-protection guideline in two of the Kisco River samples 

(4 percent), carbaryl, chlorpyrifos, and malathion exceeded 

the aquatic-life-protection guideline in one of these samples 

(2 percent); the 2,4-D concentrations exceeded the aquaticlife-protection guideline in two (8 percent), of these samples. 

Diazinon and carbaryl concentrations were greater than or equal 

to half of the aquatic-life-protection guideline in more than 13 

percent of the Kisco River samples. All exceedences of aquaticlife-protection guidelines occurred during stormflows. 

The stormflow concentrations of some insecticides 

approached the aquatic-life-protection guidelines from June 

through December 2000 (fig. 2) and exceeded them in June 

(diazinon), September (chlorpyrifos and malathion), and 

December (carbaryl); 2,4-D concentrations exceeded the 

guideline in September stormflows. These results further 

indicate that effective monitoring of runoff quality in urban 

or residential areas requires stormflow data from the growing 

season through the Fall (May through December). 

Seasonal Variability in Pesticide Concentrations 

 The highest concentrations of most pesticide and 

pesticide degradates at both sites occurred during storms. 

Unlike agricultural areas, watersheds with a large amount of 

development can produce elevated pesticide concentrations in 

storms after, as well as during, the growing season, primarily 

because of multiple applications of pesticides.

Kisco River

The highest concentrations of most herbicides and 

insecticides in the Kisco River samples were in stormflow 

samples collected in June, September, and December 2000. In 

general, the highest baseflow concentrations of most pesticides 

were in samples collected during May and June; few pesticides 

were detected in baseflow samples after September. 

Herbicides

The highest concentrations of the most frequently detected 

herbicides were found in samples collected during large storms 

in June, September, and December 2000. An exception was 

atrazine, which reached its maximum concentration during 

a small storm in May and showed a smaller response to 

stormflows than other herbicides that were found at higher 

concentrations. Peak concentrations of herbicides can sometimes 

be related to the frequency of application indicated by the 

manufacturer.

2,4-D, Imazaquin, and Diuron

The herbicides 2,4-D, imazaquin and diuron were commonly 

detected during low flows as well as stormflows in late May 

and early June, but were detected only during stormflows 

thereafter. 2,4-D and diuron were detected only during storms 

in September, November, and December, and imazaquin was 

only detected in stormflows in late July, August, and December 

(fig. 3A). Maximum concentrations of 2,4-D and imazaquin 

were detected in stormflow samples from September and 

December, respectively. The highest concentration of diuron 

was found in a stormflow sample collected in May, but elevated 

concentrations also were detected in late summer and early 

fall stormflow samples. Other herbicides that were detected at 

high concentrations, including dicamba and 2,4-D methyl ester 

(not shown in fig. 3A), showed seasonal patterns similar to 

that of 2,4-D and imazaquin – with maximum concentrations 

in September, November, or December, and detections after 

August only in stormflow samples. 

Not all stormflows contained elevated concentrations of 

2,4-D, imazaquin, or diuron. For example, the concentrations of 

2,4-D and diuron in September stormflow samples exceeded 1 

μg/L, yet no imazaquin was detected; conversely, imazaquin and 

diuron were detected in late July and August stormflow samples, 

but no 2,4-D was found (fig. 3A). 

The observed pattern of peak concentrations of some 

herbicides in June and September stormflow samples can be 

related to the manufacturer’s recommended pesticide-application 

patterns. The periods of peak 2,4-D concentrations (June 

and September 2000) in Kisco River samples are consistent 

with the application instructions on a widely used turfgrass 

formulation that is marketed for homeowner use and commonly 

sold at home and garden stores. The label for a frequently used 

herbicide containing both 2,4 D and dicamba recommends two 

applications 3 to 4 months apart during the growing season; 

this is consistent with the 3-month lag between the June and 
10

September peaks in 2,4-D concentrations (fig. 3A). Dicamba 

was detected only in samples from the small September storm, 

during which 2,4-D concentrations exceeded 0.3 μg/L. Elevated 

concentrations of both compounds during this storm probably 

reflect the timing of the application of these widely used 

herbicides in the Kisco River watershed. 

The elevated pesticide concentrations in late fall and 

winter stormflow samples from the Kisco River site reflect 

a delay in the flushing of pesticides applied, possibly as 

repeated applications much earlier. For example, the elevated 

concentrations of herbicides such as 2,4-D in the late December 

stormflow samples probably reflect the delayed flushing of 

these compounds from the soil after late summer or early fall 

A. Kisco River

����������������

M S D J F

2000 2001

RATIO OF CONCENTRATION TO AQUATIC-LIFE PROTECTION CRITERIA

�����������

Diazinon Chlorpyrifos Carbaryl Malathion

0.1

1

1

10

10

0.1

0.01

0.01

a

Notes:

a. Great Lakes aquatic life criteria (International Joint Commission, 1977)

b. Canadian aquatic life criteria (Environment Canada, 1999) 

c. U.S. Environmental Protection Agency aquatic life criteria 

(US Environmental Protection Agency, 1999) 

c b c 2,4-Db

��������������

J J A O N

Open symbol denotes concentration below detection limit.

Figure 2. Ratio of pesticide concentration to aquatic–wildlife protection standards in Kisco River and Middle Branch 

Croton River samples, Westchester and Putnam Counties, N.Y., May 2000-February 2001.
11

applications. The fall of 2000 was dry, with no storms in October 

and only a few small storms in November (fig. 3A); the storm in 

late December was the largest since late September and probably 

reflected transport of pesticides applied since October. Similarly, 

the 2,4-D in samples collected during a small November storm 

probably represents a minor flushing of this compound that 

was followed by the major flushing in December. Conversely, 

the peak imazaquin concentrations in the December stormflow 

samples probably reflect relatively late applications in the fall 

because imazaquin is sometimes applied to turfgrass after the 

first frost (Crop Data Management Systems, 2001). 

The results from Kisco River sampling suggest that the 

nationwide urban-stream study by Hoffman and others (2000), 

which predicted peak herbicide concentrations in urban and other 

developed areas of the Northeast to occur during spring and early 

summer and decreasing concentrations thereafter through the fall, 

does not fully reflect the occurrence of herbicides during the late 

summer and fall, because it did not include stormflow sampling. 

Of the 25 herbicides or herbicide degradates detected in Kisco 

River samples, 12 showed maximum concentrations in stormflow 

samples from May or June samples, 5 from September, and 8 

from November or December. Of the seven herbicide or herbicide 

degradates with maximum concentrations greater than 0.1 μg/L, 

five showed maximum concentrations in September, November, 

or December (table 2A). Again, the main reason for this 

discrepancy between the two studies is probably that the study by 

Hoffman and others (2000) did not target stormflow samples.

Atrazine

Seasonal patterns of atrazine concentrations in the Kisco 

River samples did not parallel those of 2,4-D or imazaquin; 

they were highest in May stormflow samples and decreased 

through July (fig. 3A), after which atrazine was detected only 

in samples collected during a small September storm and the 

large December storm. The decrease in atrazine concentrations 

at this site from late spring through late summer parallels the 

reported seasonal pattern of herbicide concentrations in streams 

that drain corn-growing areas in central New York – with peak 

herbicide concentrations in late spring and a steady decline 

thereafter (Wall and Phillips, 1998). This pattern indicates that 

the atrazine detected in the Kisco River is derived mainly from 

spring applications in agricultural areas, either upstream within 

the watershed or outside the watershed and deposited through 

atmospheric drift. The presence of atrazine in the December 

stormflow sample probably reflects either the storage of 

atrazine in the soil and subsequent flushing several months after 

application, or direct flushing after a late application in the fall. 

Fall application of atrazine, if it occurred, would probably have 

been for some purpose other than agriculture because atrazine is 

mostly applied on cropland in New York in the spring. 

Prometon

Concentrations of prometon in Kisco River samples remained 

nearly constant from May through September (fig. 3A), with a 

peak concentration during a small September storm. Prometon is 

frequently mixed with paving materials; therefore, the constant 

concentrations at the Kisco River site probably are derived from 

a steady migration of this herbicide from paved surfaces. 

Insecticides

The three most commonly detected insecticides (diazinon, 

carbaryl, and imidacloprid) were found in all Kisco River 

samples collected from May through August, regardless of 

flow conditions, and in stormflow collected from September 

through December (fig. 3A). After mid-August, imidacloprid 

was detected only during the December storm. Unlike many of 

the herbicides detected in this study, the insecticides diazinon, 

carbaryl, and imidacloprid were detected mostly in base-flow 

samples collected from June through August, and the base-flow 

concentrations sometimes approached stormflow concentrations 

(fig. 3A). The occurrence of these insecticides at elevated 

concentrations throughout the growing season could reflect a 

nearly constant application in a variety of settings, including 

lawns, ornamental plantings, and home pest control. 

Of the 9 insecticides and their degradates found in Kisco 

River samples, one had peak concentrations in June, three had 

peak concentrations in July, two had peak concentrations in 

September, and three had peak concentrations in November 

or December (table 2A); the peak concentrations generally 

occurred during stormflows. Although a study of urban streams 

throughout the Northeast by Hoffman and others (2000) found 

that total insecticide concentration was highest in midsummer 

and early fall, the Kisco River results indicate that elevated 

insecticide concentrations can persist into the late fall. This 

discrepancy could reflect the absence of stormflow samples in 

the study by Hoffman and others (2000).

Middle Branch

 Samples from Middle Branch show some of the seasonal 

patterns in herbicide and insecticide concentrations seen in the 

Kisco River data. However, the lower detection frequency and 

lower peak concentrations (a reflection of the lower population 

density and smaller amounts of developed land), along with 

streamflow regulation at the Lake Carmel outlet 1.5 mi above 

the Middle Branch site, make it difficult to assess the effect that 

changes in streamflow have on pesticide concentrations. 

Herbicides

2,4-D was commonly detected in samples collected in May 

and June; imazaquin was detected less frequently, and diuron 

was not detected at all during this period. After July, 2,4-D and 

diuron were detected only in stormflow samples collected in 

September, November, and December (fig. 3B). Although the 

storm in late September did not cause a substantial increase in 

stream discharge in Middle Branch (although it did in the Kisco 

River), the concentrations of diuron and 2,4-D increased during 

these storms. After June, imazaquin was detected only in a 

stormflow sample collected in December. 
12

Concentrations of atrazine in the Middle Branch were highest 

in May and decreased slightly through August (fig. 3B), and the 

concentration patterns observed in samples from this site were 

generally similar to those observed in Kisco River samples. 

After August, atrazine was detected only in samples collected 

during a small storm in September and was not detected during 

the December storm. This may indicate a lack of atrazine 

application in the Middle Branch watershed during the fall, 

unlike the Kisco River watershed. Concentrations of prometon 

remained nearly constant from May through September (fig. 

3B), although a peak concentration occurred during a small July 

storm. Of the 17 herbicides or herbicide degradates detected in 

Middle Branch samples, 11 had peak concentrations in May or 

June, unlike the peak concentration of herbicides in Kisco River 

samples, half of which occurred during September, November, 

or December. 

Insecticides

As in the Kisco River samples, diazinon was often detected in 

Middle Branch samples collected from July through September 

(fig. 3B), regardless of flow conditions, but was not detected in 

any samples collected from this site after October 1. Carbaryl 

was detected infrequently; the few detections were in stormflow 

samples from May, October, and November. Imidacloprid was 

not detected in any Middle Branch samples. Peak insecticide 

concentrations in Middle Branch samples occurred in July or 

later; one insecticide and one insecticide degradate had peak 

concentrations in July, and the three other insecticides or 

degradates had peak concentrations in November or December. 

2,4-D

Diuron

Imazaquin

Prometon

Atrazine

Diazinon

Carbaryl

Imidacloprid

0.1

1

0.01

0.001

10

30

0.1

0.01

0.001

CONCENTRATION, IN MICROGRAMS PER LITER

1

150

200

100

50

0

150

200

250

100

50

0

150

200

250

100

50

0

STREAM DISCHARGE, IN CUBIC FEE PER SECOND

250

0.1

0.01

0.001

M J J A S O N D J F

2000 2001

Insecticides

NOTE: Open symbol denotes concentrations below detection limit

Figure 3A. Concentration of eight pesticides in Kisco River samples collected May 

2000-February 2001, Westchester County, N. Y. [Sampling location is shown in fig. 1.].
13

Effects of Stormflow on Pesticide Concentrations in 

Kisco River Samples 

Streamflow above the Middle Branch sampling site is 

regulated by Lake Carmel, 1.5 mi upstream; therefore, data from 

this site are not discussed in this section. 

Concentrations of many herbicides and insecticides at the 

Kisco River site increased during some of the stormflows, as 

described below. 

Herbicides

The Kisco River data indicate that the relation between storm 

discharge and herbicide concentrations varies among compounds 

and differs from storm to storm, and that not all stormflows 

produced increased concentrations of herbicides. Concentrations 

of 2,4-D and diuron increased with increasing discharge during 

the September storm (fig. 4), and peaked during the maximum 

stream discharge. This was presumably the result of surface 

washoff of these herbicides from lawns and other areas to which 

they had been applied. Concentrations of these compounds 

increased only slightly during the June storm, however, and 

2,4-D concentrations during the December storm at this site 

did not correlate with stream discharge (fig. 4). During the 

December storm, some herbicides, such as imazaquin, showed 

peak concentrations on the rising limb of the hydrograph, and 

decreasing concentrations during the peak discharge and on the 

recession limb.

Atrazine concentrations increased during the stormflows of 

June and December, but this compound was not detected in any 

September stormflow samples. Atrazine concentrations during 

the June and December storms were highest during the rising 

limb of the hydrograph; the peak concentrations occurred near 

the initial discharge peak on the rising limb. 

�����

������

���������

��������

��������

��������

��������

���

�

����

�����

��������������������������������������

���

�

����

�����

��

���

���

�

��

�����������������������������������������

��

���

���

�

��

��

���

���

�

��

���

����

�����

� � � � � � � � � �

���� ����

������������

��������������������������������������������������������������

Figure 3B. Concentration of seven pesticides in Middle Branch Croton River samples 

collected May 2000-February 2001, Putnam County, N. Y. [Sampling location is shown 

in fig. 1.] 
14

Prometon concentrations did not change during any 

stormflows. This steady pattern indicates a relatively slow but 

constant inflow of prometon from within the watershed.

Insecticides

Concentrations of insecticides in the Kisco River did not 

always increase with increasing stream discharge during storms 

(fig. 4). Typically, a storm hydrograph for the Kisco River site 

has two discharge peaks – an initial peak on the rising limb, 

followed by a decrease for a few hours, then a second peak that 

normally exceeded the initial peak. The peak concentration of 

diazinon coincided with the initial discharge peak of the June 

and September storms, and, to a lesser degree, with the initial 

peak of the December storm. In contrast, peak concentrations 

of carbaryl occurred later, just before the second discharge peak 

in the June storm, and after the second peak discharge of the 

December storm. Peak concentrations of imidacloprid, like those 

of diazinon, coincided with the initial discharge peak during the 

June and December storms. The carbaryl concentrations were 

anomalous in that they declined after the initial discharge peak in 

the December storm, then rose on the falling limb. 

�

��

��

���

����

�����

���

����

�����

�������� ��������

�������� �������� ������������

���

�

����

�����

����� ��������� ������

�����������

��������������������������������������

���

���

���

���

��

�

���

���

���

���

��

�

���

���

���

���

��

�

�����������������������������������������

����

� � � � �� �� �� �� �� ��

��������� ��������

��������������������������������������������������������������

�����������

�����������

Figure 4. Concentration of selected compounds in Kisco River samples collected 

during storms in June, September, and December 2000. [Sampling location is shown 

in fig. 1.]
15

The occurrence of peak pesticide concentrations during 

the initial discharge peak rather than the main discharge peak 

could reflect a variety of factors. The initial discharge peak of 

the Kisco River hydrographs probably represents runoff from 

extensively paved areas, which presumably contribute greater 

amounts of runoff during the initial part of a storm than pervious 

(unpaved) areas. A peak pesticide concentration during the initial 

discharge peak could therefore reflect the runoff of pesticides 

inadvertently applied to, or spilled on, paved areas and, possibly, 

a greater use of pesticides in highly developed (extensively 

paved) areas. The occurrence of peak pesticide concentrations on 

the second peak or falling limb of the hydrograph may indicate 

washoff of pesticides from areas with little pavement, or the 

arrival of pesticides from parts of the watershed far from the 

sampling site. 

SUMMARY AND CONCLUSIONS

Two tributaries to the Croton watershed (the Kisco River 

and Middle Branch) were sampled as part of a cooperative 

project between the USGS and New York State Department 

of Environmental Conservation to assess the occurrence of 

pesticides in surface waters of the Croton watershed. Pesticide 

sampling of stormflow and base-flow samples from the Kisco 

River and Middle Branch from May 2000 through February 

2001 resulted in detection of over 30 pesticides or pesticide 

degradates in Kisco River samples and 20 pesticides or pesticide 

degradates in Middle Branch samples. Four compounds (the 

herbicides 2,4-D, 2,4-D methyl ester, dicamba, and the fungicide 

metalaxyl) were detected at concentrations above 1 μg/L in at 

least one sample from the Kisco River; no compounds were 

detected at concentrations above 0.4 μg/L in Middle Branch 

samples, and only two compounds (the herbicides 2,4-D and 

prometon) were detected at concentrations above 0.3 μg/L in 

one or more Middle Branch samples. No human-health-based 

water-quality standards were exceeded in any samples from 

either site, but four insecticides (carbaryl, diazinon, malathion, 

and chlorpyrifos) and one herbicide (2,4-D) in Kisco River 

samples exceeded guidelines for the protection of aquatic life. 

No guidelines for the protection of aquatic life were exceeded in 

any Middle Branch samples.

Concentrations were generally higher, and the number of 

compounds detected were greater, in samples from the Kisco 

River than in samples from Middle Branch, probably because the 

Kisco River watershed contains a higher population density and 

a larger percentage of developed land than the Middle Branch 

watershed. The chlorophenoxy herbicides 2,4-D, 2,4-D methyl 

ester and dichlorprop, the herbicides diuron and imazaquin, and 

the insecticides diazinon and carbaryl, all of which are used in a 

variety of developed settings, were frequently detected in Kisco 

River samples. 

The maximum concentrations of some of the most commonly 

detected herbicides occurred in the Kisco River during large 

storms in June, September, and December. Not all stormflows 

showed increased concentrations of all compounds, but the 

peak concentrations of some compounds, including 2,4-D and 

imazaquin, were detected during storms that occurred shortly 

after the recommended months of application. Three commonly 

detected insecticides (diazinon, carbaryl, and imidacloprid) 

were frequently detected in stormflow and baseflow samples 

collected from May through August, but were not detected in 

any baseflow samples collected after August. The detection of 

insecticides throughout the growing season could be a result of a 

near-constant rate of application of these compounds throughout 

this period. The elevated pesticide concentrations in late fall and 

winter samples could have been caused by a drought-induced 

delay in the flushing of pesticides applied much earlier in the 

fall, or they could result from late applications (after the first 

frost). 

The relation between stream discharge and pesticide 

concentration during Kisco River stormflows varied among 

compounds and from storm to storm. The concentrations of 

2,4-D and diuron increased with increasing discharge during 

the September storm and peaked during the maximum stream 

discharge. The 2,4-D concentrations during the December 

storm at this site, however, did not correlate with discharge. 

Peak concentrations of diazinon during the June storm occurred 

during an initial discharge peak, whereas peak concentrations 

of carbaryl peaked later in this storm, just before peak 

discharge. The occurrence of peak pesticide concentrations 

during the initial discharge peak could reflect the washoff of 

pesticides inadvertently applied to or spilled on paved areas 

in the watershed, or the wide use of pesticides within this 

highly developed watershed. The occurrence of peak pesticide 

concentrations during the latter part of the storm may reflect 

pesticide use in areas with little pavement or in parts of the 

watershed that are far from the sampling point. 

Acknowledgements

Although the information in this document has been funded 

wholly or in part by the United States Environmental Protection 

Agency under assistance agreement X-99273899 to New York 

State Department of Environmental Conservation, it has not 

gone through the Agency’s publications review process and 

therefore, may not reflect the views of the Agency and no 

official endorsement should be inferred. Samples were collected 

by Dan Edwards and Jason Martin. Editorial assistance was 

provided by Ann Finch, Patricia Lee and Susan Bergin. 

References Cited

Bureau of the Census, 1991a, Census of population and housing, 1990: 

Public Law 94-171 data (United States) [machine-readable data 

files]: Washington, D.C., The Bureau [producer and distributor]. 

Bureau of the Census, 1991b, Census of population and housing, 1990: 

Public Law 94-171 data technical documentation: Washington, D.C., 

The Bureau. 

Canadian Council of Resource and Environment Ministers, 1997, 

Canadian water quality guidelines (rev. ed.): Ottawa, Ontario, Task 

Force on Water Quality Guidelines, Canadian Council of Resource 
16

and Environment Ministers, loose-leaf (originally published 1987), 

23 appendixes. 

Crop Data Management Systems, 2001, Image 70 DG Specimen Label, 

NVA 2001-04-151-0165 9/00 (http://www.cdms.net/1dat/1d3SG005.

pdf), accessed on 3/11/2003.

Eckhardt, D. A., and Burke, Sarah, 1999, Pesticide residues in Hemlock 

and Canadice Lakes and their tributaries in western New York, 1997-

98: U.S. Geological Survey Water-Resources Investigations Report 

99-4271, 4 p. 

Environment Canada, 1999, Canadian water quality guidelines for 

the protection of aquatic life, Summary tables, (http://www.ec.gc.

ca/ceqg-rcqe, accessed on 6/23/99. 

Furlong, E. T., Anderson, B. D., Werner, S. L., and others, 2001, 

Methods of analysis by the U.S. Geological Survey National 

Water Quality Laboratory � Determination of pesticides in water 

by graphitized Carbon-based solid-phase extraction and highperformance liquid chromatography/mass spectrometry: U. S. 

Geological Survey Water-Resources Investigations Report 01-4134, 

81 p.

Harrison, S. A., Watschke, T. L., Mumma, R. O., Jarrett, A. R., and 

Hamilton, G. W., 1993, Nutrient and pesticide concentrations in 

water from chemically treated turfgrass, in Racke, K. D., and Leslie, 

A. R., eds., Pesticides in urban environments fate and significance: 

Washington, D.C., American Chemical Society, American Chemical 

Society Symposium Series 522, p. 191-207. 

Hoffman, R. S., Capel, P. D., and Larson, S. J., 2000, Comparison of 

pesticides in eight U.S. urban streams: Environmental Toxicology 

and Chemistry, v. 19, p. 2249-2258.

International Joint Commission Canada and United States, 1977, New 

and revised Great Lakes water quality objectives, volume II, an IJC 

report to the governments of the United States and Canada: Windsor, 

Ontario, Canada, International Joint Commission (http://www.ijc.

org/agree/quality.html#art5). 

Ma, Q.L., Smith, A.E., Hook, J.E., Smith, R.E., and Bridges, D.C., 

1999, Water runoff and pesticide transport from a golf course fairway 

Observations vs. opus model simulations: Journal of Environmental 

Quality, v. 28, p. 1463-1473. 

New York State Department of Health, 1998, Water quality regulations 

for surface and groundwaters; Title 6 chapter X (Parts 703.5, Table 

1), 10 NYCRR Subpart 5-1: Albany, New York State Department of 

Health Public Water Systems Regulations, effective March 12, 1998.

Pesticide Action Network, 2002, Pesticide Action Network Pesticide 

Database – Pesticide Products – Product Search (http://www.

pesticideinfo.org/PCW/ , accessed on 12/02/2002. 

Phillips, P. J., and Bode, R. W., 2002, Pesticides and their Degradates in 

the Croton Reservoir System, New York, July-September 2000, U.S. 

Geological Survey Water-Resources Investigations Report 02-4063, 

20 p. 

Phillips, P. J., Wall, G. R., Eckhardt, D. A., Freehafer, and Rosenmann, 

Larry, 1998, Pesticide concentrations in surface waters of New York 

State in relation to land use – 1997: U.S. Geological Survey WaterResources Investigations Report 98-4104, 10 p. 

Phillips, P. J., Eckhardt, D. A., and Rosenmann, Larry, 1999, Pesticides 

and their metabolites in three small public water-supply reservoir 

systems, Western New York, 1998-99: U.S. Geological Survey 

Water-Resources Investigations Report 99-4278, 24 p. 

Phillips, P. J., Eckhardt, D. A., Smith, M. A., and Rosenmann, Larry, 

2000, Pesticides and their metabolites in selected surface-water 

public supplies in New York State, 1999: U.S. Geological Survey 

Water-Resources Investigations Report 00-4119, 16 p. 

Sandstrom, M. W., Stroppel, M. E., Foreman, W. T., and Schroeder, 

M. P., 2001, Methods of analysis by the U.S. Geological Survey 

National Water Quality Laboratory � Determination of moderateuse pesticides and selected degradates in water by C-18 solidphase extraction and gas chromatography/mass spectrometry: U.S. 

Geological Survey Water-Resources Investigations Report 01-4098, 

70 p.

Shelton, L. R., 1994, Field guide for collecting and processing streamwater samples for the National Water Quality Assessment Program: 

U.S. Geological Survey Open-File Report 94-455, 42 p.

Templeton, S. R., Zilberman, D. and Yoo, S. J., 1998, An economic 

perspective on outdoor residential pesticide use: Environmental 

Science and Technology v. 32, p. 417A-423A.

U.S. Geological Survey, 1998, Digital map file of land cover for the 

Environmental Protection Agency Region II, Version 98-07: EROS 

Data Center, Sioux Falls, S. D., 1:100,000-scale, 1 sheet.

U.S. Environmental Protection Agency, 1999, Compilation of national 

recommended water quality criteria and EPA’s process for deriving 

new and revised criteria, Office of Water. (http://www.epa.gov/OST/

standarads/wqcriteria.html), accessed on 5/25/99. 

Wotzka, P.J., Capel, P.D., Ma, L., and Lee, J.T., 1998, Pesticide 

transport and cycling in the Lake Harriet Watershed, Minneapolis, 

Minnesota: Minneapolis Lakes and Parks- Special Session 

Preceedings, Sixteenth Annual North American Lake Management 

Society International Symposium. 

Wall, G.R., and Phillips, P.J., 1998, Pesticides in the Hudson River 

basin, 1994-96: Northeastern Geology and Environmental Sciences, 

v. 20, no. 4, p. 299-307. 

Zaugg, S. D., Sandstrom, M. W., Smith, S. G., and Fehlberg, K. M., 

1995, Methods of analysis by the U.S. Geological Survey National 

Water Quality Laboratory Determination of pesticides in water by C18 solid-phase extraction and capillary-column gas chromatography 

with selective-ion monitoring: U.S. Geological Survey Open-File 

Report 95-181, 49 p.

For additional information about this report 

write to:

U.S. Geological Survey

425 Jordan Road

Troy, NY 12180

Email: askny@usgs.gov

World Wide Web: http://ny.usgs.gov/

For sale by:

U.S. Geological Survey, 

Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and 

its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Printed on recycled paper