U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5009

Prepared in cooperation with the National Park Service

Water Quality of the Upper Delaware Scenic and Recreational 

River and Tributary Streams, New York and Pennsylvania
Cover. Photograph of the Upper Delaware River, 1993, by David B. Soete, Upper Delaware Council, Narrowsburg, NY.
Water Quality of the Upper Delaware 

Scenic and Recreational River and Tributary 

Streams, New York and Pennsylvania

By Jason Siemion and Peter S. Murdoch

Prepared in cooperation with the National Park Service

Scientific Investigations Report 2010–5009

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:

Siemion, Jason, and Murdoch, P.S., 2010, Water quality of the Upper Delaware Scenic and Recreational River and 

tributary streams, New York and Pennsylvania: U.S. Geological Survey Scientific Investigations Report 2010–5009, 

43 p., available online only at http://pubs.usgs.gov/sir/2010/5009/.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Description of the Study Area ............................................................................................................2

Climate and Hydrology.........................................................................................................................2

Water-Quality Concerns ......................................................................................................................4

Previous Investigations........................................................................................................................6

Existing Water-Quality Guidelines......................................................................................................6

Methods of Study...........................................................................................................................................7

Relation Between Land Use and Water Quality .......................................................................................7

Water-Quality Statistics: Existing Water Quality .....................................................................................9

Water-Quality-Condition Assessment: Nutrients ....................................................................................9

Tiered Monitoring Strategy Water-Quality Results................................................................................14

Regional Stream Surveys ..................................................................................................................17

Gradient and Intensive Site Networks ............................................................................................17

Chemical and Total Suspended Solids Yields .........................................................................................23

Summary........................................................................................................................................................23

Acknowledgments.......................................................................................................................................24

References Cited..........................................................................................................................................24

Appendix 1. Land Use in Drainage Areas of Sites Sampled during the Upper Delaware River

(UPDE) Study...................................................................................................................................27

Appendix 2. Water-Quality Statistics for the Intensive and Gradient Study Sites, Upper

Delaware River Basin, October 2005 to September 2007 ........................................................29

Appendix 3. Yields of Selected Constituents for Intensive Sites in the Upper Delaware

River Basin, October 2005 to September 2007...........................................................................43

Figures

1. Map showing location of the Upper Delaware River (UPDE) drainage basin,

intensive and gradient study basins, and mainstem intensive, tributary intensive,

tributary gradient, and tributary regional survey sampling sites..........................................3

2. Graph showing streamflow at the Delaware River at Port Jervis, N.Y., during

water years 2006 and 2007, and dates of sample collection.................................................5

3. Map showing land use/land cover, intensive and gradient mainstem and tributary 

basins, and sampling-site locations in the Upper Delaware River drainage basin.............

4. Diagrams showing distributions of (A) acid neutralizing capacity, aluminum,

ammonium, boron, and calcium; (B) chloride, dissolved organic carbon,

magnesium, nitrate, and particulate organic carbon; (C) pH, potassium, specific

conductance, silicon, and sodium; and (D) sulfate, total dissolved nitrogen, total

phosphorous, total suspended solids, and turbidity measured at intensive and

gradient sites in the Upper Delaware River (UPDE) drainage basin, water years

2006 and 2007...............................................................................................................................10
iv

5. Map showing classifications of water quality with respect to nitrate

concentration in the Upper Delaware River (UPDE) tributary basins, water years

2006 and 2007...............................................................................................................................15

6. Map showing classifications of water quality with respect to total phosphorous

concentration in the Upper Delaware River (UPDE) tributary basins, water years

2006 and 2007...............................................................................................................................16

7. Graphs showing regional cumulative curves of basin area ranked by increasing

nitrate concentration for (A) spring 2006 high flow, (B) summer 2006 base flow, 

(C) spring 2007 high flow, and (D) summer 2007 base flow with box plots for 

selected gradient sites for the Upper Delaware River (UPDE) tributaries........................18

8. Graphs showing cumulative frequency curves of nitrate concentration, total

phosphorous concentration, pH, specific conductance, and total suspended

solids concentration for different land uses in the Upper Delaware River (UPDE)

drainage basin.............................................................................................................................19

9. Graphs showing site-specific cumulative frequency curves of nitrate

concentration, total phosphorous concentration, pH, specific conductance, and

total suspended solids concentration for agricultural sites in the Upper Delaware

River (UPDE) drainage basin.....................................................................................................20

10. Graphs showing site-specific cumulative frequency curves of nitrate

concentration, total phosphorous concentration, pH, specific conductance, and

total suspended solids concentration for forested sites in the Upper Delaware

River (UPDE) drainage basin.....................................................................................................21

11. Graphs showing site-specific cumulative frequency curves of nitrate

concentration, total phosphorous concentration, pH, specific conductance, and

total suspended solids concentration for suburbanized sites in the Upper

Delaware River (UPDE) drainage basin ..................................................................................22

12. Graph showing spatial-temporal cumulative curves for nitrate and total

phosphorous concentrations in the Upper Delaware River (UPDE) drainage basin

and an example theorized ideal curve ....................................................................................22

Tables

1. Mean annual air temperature and mean annual precipitation for three sites 

over an elevation gradient in the Upper Delaware River (UPDE) drainage basin, 

1970–2000 .......................................................................................................................................4

2. Annual mean air temperature, maximum daily temperature, minimum daily

temperature, total precipitation, and maximum daily rainfall for three sites over an

elevation gradient in the Upper Delaware River (UPDE) drainage basin............................4

3. Peak discharge for selected sites in the Upper Delaware River (UPDE) drainage

basin during the June 2006 flood and median annual peak flow..........................................5

4. Scenic Rivers Monitoring Program definition of water quality for selected

constituents and properties in the Delaware River between the confluence of the

East Branch and West Branch Delaware River and Port Jervis, N.Y. ................................6

5. Values of selected common constituents and properties for original Scenic Rivers

Monitoring Program (SRMP) water quality (Delaware River Basin Commission,

2008b), existing main stem Delaware River water quality, nutrient criteria (Smith

and others, 2006), and U.S. Environmental Protection Agency (USEPA)

ecoregional reference conditions ...........................................................................................14
v

Conversion Factors, Datum, and Abbreviations

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

hectare (ha) 0.003861 square mile (mi2

) 

square kilometer (km2) 0.3861 square mile (mi2

)

Flow rate

cubic meter per second (m3

/s) 35.31 cubic foot per second (ft3

/s)

Mass

kilogram (kg) 2.205 pound avoirdupois (lb)

megagram (Mg) 1.102 ton, short (2,000 lb)

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

°F=(1.8×°C)+32

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25°C).

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).

Vertical coordinate information is referenced to the North American Vertical Datum of 1983 

(NAVD 83).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations used in this report

ANC Acid neutralizing capacity

DRBC Delaware River Basin Commission

kg/ha kilograms per hectare

NA Not available

NPS National Park Service

r

2 Coefficient of determination

SPW Special Protection Waters

SRMP Scenic Rivers Monitoring Program

UPDE Upper Delaware Scenic and Recreational River

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey
This page has been left blank intentionally.
Water Quality of the Upper Delaware Scenic and 

Recreational River and Tributary Streams, New York 

and Pennsylvania

By Jason Siemion and Peter S. Murdoch

Abstract

Water-quality samples were collected from the Upper 

Delaware Scenic and Recreational River (UPDE) and its 

tributaries during the period October 1, 2005, to September 30, 

2007, to document existing water quality, determine relations 

between land use and water quality, and identify areas of 

water-quality concern. A tiered water-quality monitoring 

framework was used, with the tiers consisting of intensively 

sampled sites, gradient sites representing the range of land 

uses present in the basin, and regional stream-survey sites.

Median nitrate and total phosphorous concentrations 

were 1.15 and 0.01 mg/L (milligrams per liter) for three sites 

on the mainstem Delaware River, 1.27 and 0.009 mg/L for 

the East Branch Delaware River, 2.04 and 0.01 mg/L for the 

West Branch Delaware River, and 0.68 and 0.006 mg/L for 

eight tributaries that represent the range of land uses present 

in the basin, respectively. The percentage of agricultural land 

varied by basin from 0 to 30 percent and the percentage of 

suburbanization varied from 0 to 17 percent. There was a 

positive correlation between the percentage of agricultural 

land use in a basin and observed concentrations of acid 

neutralizing capacity, calcium, potassium, nitrate, and total 

dissolved nitrogen, whereas no correlation between the 

percentage of suburbanization and water quality was detected. 

Results of stream surveys showed that nitrate 

concentrations in 55 to 65 percent of the UPDE Basin 

exceeded the nitrate reference condition and a suggested 

water-quality guideline for ecological impairment in New York 

State (0.98 mg/L) during the spring. Many of the affected parts 

of the basin were more than 90 percent forested and showed 

signs of episodic acidification, indicating that the long-term 

effects of acid deposition play a role in the high nitrate levels. 

Nitrate concentrations in 75 percent of samples collected from 

agricultural sites exceeded the suggested nitrate water-quality 

guideline for ecological impairment. Concentrations of nitrate 

and total phosphorous in samples collected from agricultural 

sites also were twice and 25 percent higher than those in 

samples from reference sites, respectively. 

Introduction

The Upper Delaware Scenic and Recreational River 

(UPDE) is a 118-km section of the uppermost mainstem reach 

of the Delaware River, designated by Congress in 1978 to 

protect its high water quality and natural and cultural resources 

under the Wild and Scenic Rivers Act (Conference of Upper 

Delaware Townships, 1986). A 225-km2

 river corridor was 

established to meet the resource-protection requirements of the 

Act, but the National Park Service (NPS) owns only a small 

portion of the land within this corridor, and therefore relies 

largely on the Special Protection Waters (SPW) designation 

and local zoning to protect the resource and its water-quality 

values (Conference of Upper Delaware Townships, 1986). 

“The Delaware River Basin Commission (DRBC) adopted 

Special Protection Waters regulations in 1992 for point source 

(or “end-of-pipe”) discharges and in 1994 for non-point source 

pollutant loadings carried by runoff to protect existing high 

water quality in areas of the Delaware River Basin deemed to 

have exceptionally high scenic, recreational, ecological and 

(or) water supply values” (Delaware River Basin Commission, 

2008a). SPW regulations are based on a whole-drainagebasin management approach in which new contaminant 

loadings are reduced or eliminated to maintain existing water 

quality or move water quality to more natural conditions 

(Delaware River Basin Commission, 2004 and 2008b). A 

detailed description of SPW regulations is available from the 

DRBC (2008a). 

 The Scenic Rivers Monitoring Program (SRMP) was 

initiated in 1984 by the DRBC and NPS to monitor water 

quality in a 195-km segment of the Delaware River and 

its tributaries, including the UPDE (Delaware River Basin 

Commission, 2004). As part of the SRMP, samples were 

collected at a set of boundary and intrastate control points 

(tributary mouths and sites along the mainstem Delaware 

River) and reach-wide existing water quality was assessed 

as the mean and 95-percent confidence limits of the mean 

(Delaware River Basin Commission, 2004). Problems with 

the assessment led the DRBC to determine that existing 
2 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

water quality needed to be documented as a basis for sitespecific concentration and loading targets, and that new SPW 

regulations would be established in terms of medians and the 

95-percent confidence limits of the median. 

To help meet this need, the U.S. Geological Survey 

(USGS), in cooperation with the NPS, applied a tiered 

monitoring framework that follows the example established 

for the Delaware River Basin through the Collaborative 

Environmental Monitoring and Research Initiative (Murdoch 

and others, 2008). In this data-collection framework, 

intensively monitored streamgages are nested within regional 

surveys to cost-effectively monitor both temporal and spatial 

variability in ecosystem properties. 

Resource management requires the use of sitespecific data, whereas policy decisions require regional 

characterizations (Olsen and others, 1999). Intensive and 

gradient water-quality sampling was used to define existing 

water quality for specific sites. Cumulative curves were 

generated to describe property conditions in the population of 

sampling sites, allowing the intensively sampled sites to be 

placed in a regional context (Herlihy and others, 2000). This 

combination of site-specific and survey data allowed for an 

improved assessment of water quality, providing scientific 

support for management decisions (Bolgrien and others, 

2005). Additionally, as part of the project, the watershed 

area for each river reach and tributary sampled in the study 

was delineated, land use within each watershed (percent 

agricultural, forest, and suburban) was determined, and maps 

of water-quality status were developed. 

Purpose and Scope

The purpose of this report is to describe existing water 

quality, relations between land use and water quality, and areas 

of water-quality concern within the UPDE and its tributaries 

during water years 2006 and 2007. (A water year is the period 

from October 1 to September 30, and is designated by the 

calendar year in which it ends.) Major ions, nutrients, pH, acid 

neutralizing capacity (ANC), and total suspended solids are 

the water-quality constituents and properties discussed in the 

report. Summary statistics, box plots, and cumulative curves 

are used to describe water quality at each of 13 intensively 

monitored sites as well as more than 40 stream-survey sites. A 

detailed discussion of the use of cumulative curves to assess 

changes in future water quality also is provided.

Description of the Study Area

The reach of the Delaware River included in the study 

extends from just upstream from the confluence of the east 

and west branches of the Delaware River downstream to Port 

Jervis, N.Y. (fig. 1). The total drainage area upstream from the 

Port Jervis sampling location is 7,960 km2

, 3,567 km2 of which 

drains into the UPDE through the east and west branches 

of the Delaware River. This drainage area is dominated by 

forested landscapes (about 80 percent) with some agriculture 

(about 10 percent) and a small amount of suburbanized land 

(about 5 percent). Although the percentage of the study area 

that is suburbanized is currently small, it is increasing and 

is concentrated along river corridors. The population in the 

Pennsylvania counties bordering the river (Pike and Wayne 

Counties) increased by 100 and 25 percent, respectively, from 

1990 to 2005 (U.S. Census Bureau, 2008).

The watersheds that drain to the study area make 

up the northernmost portion of the Appalachian Plateau 

physiographic province. The east and west branches of the 

Delaware River drain the western portions of the Catskill 

Mountains, with elevations ranging from 300 to 1,200 m. 

Bedrock in this area consists primarily of nearly flat-lying 

sandstone, shale, and conglomerate with thin soils on ridge 

tops. Both the east and west branches of the Delaware River 

are dammed to provide drinking water for New York City, 

with the outflows regulated to maintain minimum flows to 

downstream users. The Lackawaxen River drains a portion of 

the Pocono Plateau and is the third largest tributary that drains 

to the study area. Flows in a portion of the Lackawaxen Basin 

are regulated for power generation, as is the Mongaup River, 

the fourth largest tributary to the UPDE.

The Delaware River is the only major river along the 

Atlantic Coast that remains undammed along its entire 

mainstem (533 km), allowing anadromous and catadromous 

fish access to historic habitat (as on few other river systems of 

this size in the eastern United States) and maintaining much 

of its rich native biodiversity. Water quality in the river’s 

upper reaches is good, supporting fisheries and recreational 

resources. The Upper Delaware has been acclaimed as one 

of the most prolific wild trout rivers east of the Mississippi 

River (Novick, 1993), supports populations of the federally 

endangered dwarf wedge mussel, and is one of the largest and 

most important inland bald eagle wintering habitats in the 

eastern United States (P.E. Nye, New York State Department 

of Environmental Conservation Endangered Species Unit, 

written commun., 1996). 

Climate and Hydrology

Mean annual air temperature and precipitation at three 

sites over an elevation gradient in the UPDE Basin for the 

period 1970 to 2000 are given in table 1. The annual mean 

air temperature, maximum daily temperature, minimum 

daily temperature, total precipitation, departure from normal 

precipitation, and maximum daily rainfall for the same sites 

for 2006 and 2007 are given in table 2. Precipitation was 

evenly distributed throughout the year, with the bulk of snow 

falling from December to March. 

The hydrograph for the study period at the Delaware 

River at Port Jervis streamgage is shown in figure 2 as an 

example of the flow conditions during the study. A regionwide flood event took place in late June 2006. Major 

tributaries experienced initial rises on June 25th and peak 
Introduction 3

Figure 1. Location of the Upper Delaware River (UPDE) drainage basin, intensive and gradient study basins, and 

mainstem intensive, tributary intensive, tributary gradient, and tributary regional survey sampling sites.

75°30' 75° 74°30'

42°30'

42°

41°30'

West Branch Delaware River

Calkins Creek

East Branch Delaware River

Callicoon Creek

Mongaup River

Lackawaxen River

 West 

Colang Creek

 Twin

Lakes Creek

Halfway 

 Brook

 Mill 

Brook

Port Jervis

80° 75°

45°

40°

UPDE

Basin

Pennsylvania

New York

New Jersey

Base from U.S. Geological Survey 1:24,000 digital raster graphic, North American Datum 1983, 

Universal Transverse Mercator Projection, Zone 18.

0 10

0 10 20 KILOMETERS

20 MILES

Mainstem intensive sites

Tributary intensive sites

Tributary gradient sites

Tributary regional survey sites

Upper Delaware administrative boundary

EXPLANATION

Upper Delaware drainage basin
4 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

flows on June 28th. By July 6th, flows at most sampling sites 

had returned to within 5 percent of pre-storm base-flow values. 

This flood event was a period-of-record peak flow for many 

sites and had a recurrence interval of greater than 100 and less 

than 500 years at all the intensive sites, with the exception 

of the Delaware River at Port Jervis, where the recurrence 

interval was 80 years (Suro and others, 2009). The peak 

discharge at each mainstem site and the East Branch and West 

Branch Delaware River sites during the June 2006 flood are 

compared to the median annual peak flow in table 3.

During the evening of June 19, 2007, a period of intense 

rainfall occurred in the watershed of the Beaver Kill, a 

tributary to the East Branch Delaware River in the western 

Catskill Mountains of New York. The occurrence of this 

localized, intense storm over two small headwater basins 

with a combined area of 35 km2

 measurably influenced water 

quality 100 km downstream on the Delaware River. According 

to the National Weather Service, 15 to 20 cm of rain fell from 

1630 to 1930 Eastern Standard Time, with local observations 

totaling 15 to 28 cm (Schaffner and others, 2007). National 

Weather Service analysis of the data indicated the event to be 

twice the 3-hour, 100-year rainfall extreme, with some rainfall 

rates exceeding 2.5 cm per 15 minutes (Schaffner and others, 

2007). The return period for the flood in one of the affected 

headwater streams was estimated to be 500 years (Schaffner 

and others, 2007).

Water-Quality Concerns

Several stressors can affect water quality in the 

watersheds that drain to the UPDE, including the long-term 

effects of acid rain, climate change and variability, and runoff 

from agricultural and suburbanized lands. Each of these issues 

is discussed briefly below.

Although decreases in acid precipitation and associated 

streamwater sulfate and nitrate concentrations have been 

Table 2. Annual mean air temperature, maximum daily temperature, minimum daily temperature, total precipitation, and maximum 

daily rainfall for three sites over an elevation gradient in the Upper Delaware River (UPDE) drainage basin.

[Data from National Climatic Data Center, 2008;  ̊C, degrees Celsius; cm, centimeters]

Site Year

Annual 

mean 

air temperature 

(°C)

Maximum 

daily 

air temperature 

(°C)

Minimum 

daily 

air temperature 

(°C)

Annual 

total 

precipitation 

(cm)

Single day 

maximum 

precipitation 

(cm)

Port Jervis, NY 2006 10.2 36.1 -15 115.6 5.5

Port Jervis, NY 2007 9.6 35.6 -17.2 115.3 6.8

Delhi, NY 2006 8.6 34.4 -19.4 153.1 10.9

Delhi, NY 2007 7.1 32.8 -23.9 145.2 6.2

Slide Mountain, NY 2006 6.9 30.6 -20.0 187.1 8.0

Slide Mountain, NY 2007 6.1 29.4 -23.9 181.1 12.3

Table 1. Mean annual air temperature and mean annual precipitation for three sites over an 

elevation gradient in the Upper Delaware River (UPDE) drainage basin, 1970–2000.

[Data from National Climatic Data Center, 2008;  ̊C, degrees Celsius; cm, centimeters; m, meters]

Site

Mean 

annual 

air temperature 

(°C)

Mean 

annual 

precipitation

(cm)

Elevation 

of 

monitoring site

(m)

Port Jervis, NY 10.0 116.9 143

Delhi, NY 7.2 109.7 432

Slide Mountain, NY 5.2 161.6 808
Introduction 5

documented in the Catskill region during the last 20 years 

(Burns and others, 2006), these trends could quickly reverse 

if future increases in acid deposition were to occur. Future 

increases in acid deposition would be detected at higher flows 

initially (episodic), with base-flow water quality degrading 

more slowly over time (chronic) (Murdoch and Shanley, 2006; 

Stoddard, 1994). 

Changing climatic conditions in the Catskill Mountains 

may alter the timing and volume of discharge to the UPDE 

through the east and west branches of the Delaware River. 

During the last 50 years in the Catskill region, mean annual 

air temperature has increased 0.6°C, annual precipitation has 

increased 13.6 cm, and peak snowmelt has shifted 2 weeks, 

from early April to late March (Burns and others, 2007). 

5,000

4,000

3,000

2,000

1,000

0

STREAMFLOW, IN CUBIC METERS PER SECOND

2006 2007

Instantaneous flow

Median daily flow 1964−2006

Water-quality sample

EXPLANATION

6,000

SAJJMAMFJDNO SAJJMAMFJDNO O

2005

Figure 2. Streamflow at the Delaware River at Port Jervis, NY, during water years 2006 and 

2007, and dates of sample collection.

Table 3. Peak discharge for selected sites in the Upper Delaware River (UPDE) drainage basin during the June 2006 flood and median 

annual peak flow.

[m3/s, cubic meters per second]

U.S. Geological Survey streamgage and number

Median annual 

peak flow 

(m3

/s)

2006 flood-event 

peak flow 

(m3/s)

2006 flood-event 

rank for 

period of record

West Branch Delaware River 01426500 338 1,230 2d

East Branch Delaware River 01421000 598 2,190 1st

Delaware River at Callicoon, NY 01427510 1,130 4,080 1st

Delaware River near Barryville, NY 01428500 1,300 4,280 1st

Delaware River at Port Jervis, NY 01434000 1,720 5,350 3d
6 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

Land use in a stream’s drainage basin affects the quality 

of water in the stream. Streams that drain forested areas tend 

to have lower dissolved-solids concentrations than streams 

that drain agricultural areas. Runoff from agricultural land 

typically contains higher levels of nitrate (Gburek and Folmar, 

1999), total suspended solids (Ahearn and others, 2005), 

and total phosphorous (Gelbrecht and others, 2005) than 

runoff from forested land. The percentage of urbanization 

in a watershed has been shown to positively correlate with 

fecal coliform levels (Mehaffey and others, 2005) and total 

suspended solids concentrations (Ahearn and others, 2005). 

The combined effects of climate change and anthropogenic 

changes in the landscape are likely to alter the hydrologic 

and biogeochemical processes in the UPDE (Moore and 

others, 1997).

Previous Investigations

A study of water quality in the Delaware River Basin 

was conducted as part of the USGS National Water Quality 

Assessment Program during 1998–2001 (Fischer and others, 

2004). Nutrient, pesticide, and volatile organic compound 

concentrations were measured in selected streams throughout 

the basin. Nutrient and pesticide levels in samples from 

watersheds dominated by urban and agricultural land uses 

were found to be elevated above those in samples from 

forested watersheds. Volatile organic compounds were 

detected in sediments from many streams, and in fish tissues. 

Samples of fish tissues from one-quarter of the sites sampled 

contained mercury at levels exceeding those considered safe 

for human consumption.

The New York State Department of Environmental 

Conservation Stream Biomonitoring Unit conducted a 

macroinvertebrate biological assessment of the West Branch 

Delaware River in 2004 and concluded that all six sites visited 

were non-impacted by water-quality degradation (Bode and 

others, 2006). The same group examined 30-year trends in 

water quality based on macroinvertebrate studies for 21 of the 

sites in the UPDE study (Bode and others, 2004); all of the 

sites were assessed as being either non-impacted (14 sites) or 

“slightly impacted” (7 sites) by water-quality degradation as 

of 1999. The slightly impacted sites included Beaver Brook, 

Delaware River at Pond Eddy, Delaware River at Port Jervis, 

East Branch Delaware River at Fishs Eddy, Halfway Brook, 

Hankins Creek, and Ten Mile River.

Existing Water-Quality Guidelines

The Scenic Rivers Monitoring Program data collection 

resulted in initial Special Protection Waters regulations for the 

UPDE. These reach-wide regulations are shown in table 4.

The U.S. Environmental Protection Agency (USEPA) 

has established ecoregional reference conditions for assessing 

concentrations of total nitrogen and total phosphorous. The 

study area is in USEPA Ecoregion VIII. The ecoregional 

reference conditions for Ecoregion VIII are 0.38 mg/L for 

total nitrogen and 0.01 mg/L for total phosphorous (U.S. 

Environmental Protection Agency, 2001). 

Table 4. Scenic Rivers Monitoring Program definition of water quality for selected constituents and properties in the Delaware River 

between the confluence of the East Branch and West Branch Delaware River and Port Jervis, NY.

[From Delaware River Basin Commission, 2008b; μS/cm, microsiemens per centimeter at 25° Celsius; mg/L, milligrams per liter]

Property Mean 95-percent confidence 

limits of mean

10th and 90th 

percentiles Comments

Conductivity (μS/cm) 68 66.6 to 69.3 52 and 88 Non-seasonal; 

reachwide

Total suspended solids (mg/L) 4.0 2.9 to 5.6 2.0 and 16 Non-seasonal; 

reachwide

Total phosphorous (mg/L) 0.029 0.027 to 0.031 0.018 and 0.05 Non-seasonal; 

reachwide

Ammonia + ammonium (mg/L) 0.015 0.013 to 0.018 0.01 and 0.05

As nitrogen;

May–Sept; 

reachwide

Ammonia + ammonium (mg/L) 0.022 0.02 to 0.025 0.01 and 0.06

As nitrogen; 

non-seasonal; 

reachwide

Total Kjeldahl nitrogen (mg/L) 0.202 0.172 to 0.237 0.1 and 0.53 May–Sept; 

reachwide

Nitrate + nitrite (mg/L) 0.293 0.256 to 0.336 0.123 and 0.492 May–Sept; 

reachwide
Relation Between Land Use and Water Quality 7

A nutrient biotic index (NBI) for use with benthic 

macroinvertebrate communities was developed by Smith and 

others (2006). This index established nutrient tolerances based 

on distributions of 164 macroinvertebrate taxa over nitrate 

and total phosphorous gradients in New York State wadeable 

streams, including streams in the UPDE. Smith and others 

(2006) describe mesotrophic and eutrophic thresholds of 

0.24 and 0.98 mg/L, respectively, for nitrate and 0.0175 and 

0.065 mg/L, respectively, for total phosphorous, and suggest 

that streams in which nutrient levels exceed the eutrophic 

threshold be considered threatened by nutrient impairment.

In this report, the USEPA ecoregional water-quality 

criteria and the NBI of Smith and others (2006) are used as 

standards with which to compare existing water quality in 

the UPDE.

Methods of Study

The water-quality data for this study were collected using 

the previously mentioned tiered monitoring framework. The 

top tier consisted of seven intensively monitored sites where 

short-term temporal variability in streamwater quality was 

assessed from samples collected with automated samplers 

during storms and snowmelt. These sites included the East 

Branch and West Branch Delaware River at a point just 

upstream from the UPDE administrative boundary, three 

mainstem Delaware River sites distributed along the length of 

the study reach, and two additional tributary sites. The middle 

tier consisted of 13 sites representing the range (or gradient) 

of observed water-quality conditions at which samples were 

collected manually on a monthly basis. This gradient sampling 

network included the intensive sites as well as six tributary 

sites that represent agricultural, forested, and suburban land 

uses. The third monitoring tier consisted of a synoptic regional 

stream survey of all major tributaries to the UPDE as well as 

a set of sampling points along the mainstem Delaware River. 

Samples were collected at these sites once during spring high 

flow and once during summer base flow during both years of 

the study. Sampling sites are listed in appendix 1. 

Sampling points for all tributary basins were located as 

near the confluence with the mainstem Delaware River as 

possible, with exceptions made for co-location of sites with 

existing streamgages. During high-flow sample collection, 

manual-sampling locations were adjusted to avoid backwater 

influences from the mainstem Delaware River. Although the 

samples collected at these locations were point samples, they 

represented the integration of influences on water quality 

within the entire watershed that drains to the stream (Herlihy 

and others, 2000). Samples were collected using standard 

USGS methods (U.S. Geological Survey, 2006). 

All samples were analyzed for nutrients, major ions, pH, 

conductivity, dissolved organic carbon, particulate organic 

carbon, total suspended solids, and turbidity at the USGS New 

York Water Science Center water-quality laboratory, using 

standard methods (Lawrence and others, 1995). In addition, 

monthly samples collected at the gradient sites were analyzed 

for total phosphorous at the USGS National Water Quality 

Laboratory in Denver, Colorado. 

Stage-discharge relations were developed for the gradient 

sites that were not co-located at existing streamgages in order 

to obtain concurrent flow measurements for each sample. 

Stage-discharge relations were developed using standard 

USGS methods (Rantz and others, 1982), with at least five 

flow measurements made. Instrumentation at intensive sites 

recorded instantaneous stage, water temperature, and specific 

conductance at 15-minute intervals. Fifteen-minute discharge 

was determined based on established stage-discharge relations 

for each site.

Annual chemical loads for intensive sites were 

calculated in steps: (1) 15-minute analyte concentrations 

were derived from linear interpolation of concentrations 

measured in sequential water samples; (2) 15-minute 

discharges corresponding to the derived concentrations 

were multiplied by those concentrations to produce an 

instantaneous load; (3) the instantaneous load was multiplied 

by 15 minutes to represent the period from 7.5 minutes before 

to 7.5 minutes after the time of the derived concentration; and 

(4) the 15-minute loads were summed over the course of the 

water year to produce an annual load. Summary Statistics were 

computed using S-Plus statistical analysis software (Insightful 

Corporation, 2005).

Relation Between Land Use and 

Water Quality

The land use for each tributary watershed and selected 

sites along the mainstem of the Delaware River is shown in 

figure 3 and percentages are provided in appendix 1. Land 

use was determined using the 2001 National Land Cover 

Dataset. Most of the agriculture in the UPDE Basin was 

contained within the basins of four tributaries: the West 

Branch Delaware River, Callicoon Creek, Calkins Creek, and 

the Lackawaxen River. The study watersheds with the highest 

percentage of suburbanization were West Colang Creek and 

Twin Lakes Creek. The small towns along the length of the 

mainstem Delaware River and the East Branch and West 

Branch Delaware River make up a small percentage of the 

overall land use, and large upstream contributions to river 

flow likely minimize the effects of these suburban areas on 

downstream water quality. Localized effects on water quality 

from these towns were not investigated.

Relations between land use and chemical concentrations 

were examined for the sites on tributaries to the UPDE. 

Acid neutralizing capacity and concentrations of calcium, 

potassium, nitrate, total dissolved nitrogen, and dissolved 

phosphorous were all positively correlated with the percentage 

of the basin occupied by agricultural land use. The coefficient 

of determination (r2

) values, which ranged from 0.25 to 0.5, 
8 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

75°30' 75° 74°30'

42°30'

42°

41°30'

West Branch Delaware River

Calkins Creek

East Branch Delaware River

Callicoon Creek

Mongaup River

Lackawaxen River

 West 

Colang Creek

 Twin

Lakes Creek

Halfway 

 Brook

 Mill 

Brook

Port Jervis

80° 75°

45°

40°

UPDE

Basin

Pennsylvania

New York

New Jersey

Forest

Base from U.S. Geological Survey 1:24,000 digital raster graphic, North American Datum 1983, 

Universal Transverse Mercator Projection, Zone 18; National Land Characteristics Dataset (NLCD) 2001.

Suburban/Urban

Agriculture

Wetland

Tributary watershed

Mainstem intensive sites

Tributary intensive sites

Tributary gradient sites

Tributary regional survey sites

Water

EXPLANATION

Upper Delaware drainage basin

0 10

0 10 20 KILOMETERS

20 MILES

Figure 3. Map showing land use/land cover, intensive and gradient mainstem and tributary basins, and samplingsite locations in the Upper Delaware River drainage basin
Water-Quality-Condition Assessment: Nutrients 9

were similar to those found in other studies (Ahearn and 

others, 2005; Mehaffey and others, 2005). The same 

constituents and properties were all negatively correlated with 

the percentage of the basin occupied by forested land cover, 

but with slightly lower r2

 values. These results are similar to 

those found by Fischer and others (2004) for the Delaware 

River Basin as a whole. In contrast to their results, however, 

in the current study no relation was found between the 

percentage of suburbanization and water quality. It is possible 

that the percentage of suburbanization in the UPDE study 

basins is below a critical threshold, so the forested portions 

of the basins are masking the effects of the current level of 

suburbanization.

At the gradient and intensive tributary sites, a distinct 

pattern was found between land use and median nutrient 

concentrations. Callicoon and Calkins Creeks had the highest 

percentages of agricultural land use in their basins (29 and 

28 percent, respectively), and had the highest median nitrate 

and total phosphorous concentrations as well as the greatest 

ranges in concentration. The primarily forested basins of Mill 

Brook (94 percent) and Halfway Brook (95 percent) were 

associated with the lowest median nutrient concentrations 

and a much smaller range in observed concentrations during 

the study period. The basins with the highest percentages of 

suburbanization, West Colang Creek (17 percent) and Twin 

Lakes Creek (11 percent), were associated with median nitrate 

and total phosphorous concentrations and ranges similar to 

those of the forested basins. 

Water-Quality Statistics: 

Existing Water Quality

Water-quality statistics for the gradient and intensive 

sites are given in appendix 2 and shown graphically in 

figure 4. Median nitrate and total phosphorous concentrations 

were 1.15 and 0.01 mg/L, respectively, for three sites on the 

mainstem Delaware River; 1.27 and 0.009 mg/L, respectively, 

for the East Branch Delaware River; 2.04 and 0.01 mg/L, 

respectively, for the West Branch Delaware River; and 

0.68 and 0.006 mg/L, respectively, for eight tributaries that 

represented the range of land uses in the basin. The SRMP 

water-quality values, existing water quality, nutrient criteria, 

and ecoregional reference conditions are compared in table 5. 

Existing water quality was to be determined for specific 

boundary control points, with the DRBC using median 

values and the 95-percent confidence limits of the median for 

establishment of Special Protection Waters standards. In the 

past, reach-wide mean values of existing water quality were 

used to establish Special Protection Waters standards. The 

number of constituents and properties common to the two 

data sets was limited to those shown in table 5. In addition, 

it should be noted that these data sets were developed using 

samples collected at different sites and intervals using different 

sampling and analytical methodologies.

 Median existing specific conductance and ammonium, 

nitrate, total nitrogen, and total suspended solids 

concentrations are greater than the corresponding SRMP 

water-quality values. The only constituent whose median 

concentration was less than the SRMP value was total 

phosphorous. Differences between existing and SRMP 

water-quality values are even greater if mean values are used.

Water-Quality-Condition Assessment: 

Nutrients

Maps of tributary and mainstem Delaware River 

water-quality conditions were created for nitrate and total 

phosphorous (figs. 5 and 6, respectively). Each basin was 

classified as eutrophic, mesotrophic, or oligotrophic based on 

the nutrient thresholds proposed by Smith and others (2006). 

These nutrient thresholds were based in part on data collected 

in wadeable streams of the UPDE Basin. These classifications 

are applied to the basins as a whole; it is not implied that 

all waters in a basin are necessarily of that classification—

rather, the overall quality of waters being exported from 

that basin to the UPDE are of that class. Streams in which 

nutrient concentrations exceed the eutrophic threshold may be 

threatened by nutrient impairment.

 To be consistent with the methods of Smith and others 

(2006), median nutrient values were calculated for the period 

April through September before comparisons to the nutrient 

thresholds were made. Median nutrient values for the entire 

year were similar to those for April through September for 

most sites, with the exception of nitrate concentrations at 

Callicoon and Calkins Creeks, which were 25 and 75 percent 

greater for the entire year, respectively. The nitrate condition 

map includes the survey sites (4 samples per site) as well as 

the intensive and gradient sites (13 to 68 samples per site). The 

total phosphorous condition map includes the intensive and 

gradient sites (11 to 21 samples per site). Survey sites were not 

included in the total phosphorous map as total phosphorous 

was not measured during stream surveys.

Nitrate concentrations in the East Branch and West 

Branch Delaware River, Delaware River at Callicoon, 

Delaware River at Barryville, and Callicoon Creek all 

exceeded the eutrophic threshold. The remaining intensive 

and gradient sites were classified as mesotrophic with respect 

to nitrate. Concentrations of total phosphorous did not 

exceed the eutrophic threshold at any of the sites. Callicoon 

Creek, Calkins Creek, the Lackawaxen River, and West 

Colang Creek were classified as mesotrophic with respect to 

total phosphorous. 

With the exception of Callicoon Creek and the West 

Branch Delaware River, the watersheds classified as eutrophic 

with respect to nitrate were all greater than 87 percent 

forested. In these mostly forested basins, the primary concern 

in terms of nitrate input was the long-term effects of acid 

deposition. Nitric acid is known to have a major role in 
10 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Figure 4. Distributions of (A) acid neutralizing capacity, aluminum, ammonium, boron, and calcium; (B) chloride, dissolved organic carbon, magnesium, nitrate, and particulate organic carbon; (C) pH, potassium, specific conductance, silicon, and sodium; and (D) sulfate, total dissolved nitrogen, total phosphorous, total suspended solids, and turbidity measured at intensive and gradient sites in the Upper Delaware River (UPDE) drainage basin, water years 2006 and 2007. (Del. R., Delaware River). Calkins Creek Callicoon Creek Delaware River near Barryville, NY Delaware River at Callicoon, NY Delaware River at Port Jervis, NY East Branch Delaware River at Fishs Eddy, NY Halfway Brook Lackawaxen River Mill Brook Mongaup River Twin Lakes Creek West Branch Delaware River at Hale Eddy, NY West Colang Creek

0 5 10 15 20 25 30 35

ACID NEUTRALIZING CAPACITY, IN MILLIGRAMS 

PER LITER AS CALCIUM CARBONATE

0 50 100 150 200 250

TOTAL ALUMINUM CONCENTRATION,

IN MICROGRAMS PER LITER

0.001 0.01 0.1 1.0

AMMONIUM CONCENTRATION,

IN MILLIGRAMS PER LITER

BORON CONCENTRATION,

IN MICROGRAMS PER LITER

1 10 100

CALCIUM CONCENTRATION,

IN MILLIGRAMS PER LITER

0 2 4 6 8 10 12 14

EXPLANATION

5th percentile

10th percentile

25th percentile

Median75th percentile

90th percentile 95th percentile

A

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek
Water-Quality-Condition Assessment: Nutrients 11

0 5 10 7 20 40 30 50

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER 

0 1 2 3 4 6

DISSOLVED ORGANIC CARBON CONCENTRATION, 

IN MILLIGRAMS PER LITER

0.6 0.8 1.0 1.2

MAGNESIUM CONCENTRATION,

IN MILLIGRAMS PER LITER

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0

PARTICULATE ORGANIC CARBON CONCENTRATION, 

IN MILLIGRAMS PER LITER

0.1 10

B

1.4 1.6 1.8 2.0 2.2

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 1 100 1,000

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

EXPLANATION

5th percentile

10th percentile

25th percentile

Median75th percentile

90th percentile 95th percentile

Figure 4. Distributions of (A) acid neutralizing capacity, aluminum, ammonium, boron, and calcium; (B) chloride, dissolved organic carbon, magnesium, nitrate, and 

particulate organic carbon; (C) pH, potassium, specific conductance, silicon, and sodium; and (D) sulfate, total dissolved nitrogen, total phosphorous, total suspended solids, and turbidity measured at intensive and gradient sites in the Upper Delaware River (UPDE) drainage basin, water years 2006 and 2007. —Continued
12 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania 6.0 2.5 6.5 3.5 7.0 7.5 8.0 pH, IN STANDARD UNITS

0 0.5 1.0 1.5 2.0 3.0

POTASSIUM CONCENTRATION,

IN MILLIGRAMS PER LITER

20 40 60 80

SPECIFIC CONDUCTANCE, IN MICROSIEMENS 

PER CENTIMETER AT 25 DEGREES CELSIUS

SILICON CONCENTRATION,

IN MILLIGRAMS PER LITER

0

SODIUM CONCENTRATION,

IN MILLIGRAMS PER LITER

0 10

C

100 120 140 160 180

0.5 1.0 1.5 2.0 2.5 3.0 25 30 5 15 20

200

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

EXPLANATION

5th percentile

10th percentile

25th percentile

Median75th percentile

90th percentile 95th percentile

Figure 4. Distributions of (A) acid neutralizing capacity, aluminum, ammonium, boron, and calcium; (B) chloride, dissolved organic carbon, magnesium, nitrate, and 

particulate organic carbon; (C) pH, potassium, specific conductance, silicon, and sodium; and (D) sulfate, total dissolved nitrogen, total phosphorous, total suspended solids, and turbidity measured at intensive and gradient sites in the Upper Delaware River (UPDE) drainage basin, water years 2006 and 2007.—Continued
Water-Quality-Condition Assessment: Nutrients 13

4 1.0 5 1.4 6 7 8

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0 0.2 0.4 0.6 0.8 1.2

TOTAL DISSOLVED NITROGEN CONCENTRATION,

IN MILLIGRAMS PER LITER

0.001 0.01 0.1

TOTAL PHOSPHOROUS CONCENTRATION,

IN MILLIGRAMS PER LITER

TOTAL SUSPENDED SOLIDS CONCENTRATION, 

IN MILLIGRAMS PER LITER

0.1 0.1

TURBIDITY, IN NEPHELOMETRIC TURBIDITY UNITS

10

D

1.0 10

1 10 100 1,000 10,000 10,000 1 100 1,000

9 10 11 1.6

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

Calkins Creek

Callicoon Creek

Delaware River near Barryville, NY

Delaware River at Callicoon, NY

Delaware River at Port Jervis, NY

East Branch Delaware River at Fishs Eddy, NY

Halfway Brook

Lackawaxen River

Mill Brook

Mongaup River

Twin Lakes Creek

West Branch Delaware River at Hale Eddy, NY

West Colang Creek

EXPLANATION

5th percentile

10th percentile

25th percentile

Median75th percentile

90th percentile 95th percentile

Figure 4. Distributions of (A) acid neutralizing capacity, aluminum, ammonium, boron, and calcium; (B) chloride, dissolved organic carbon, magnesium, nitrate, and 

particulate organic carbon; (C) pH, potassium, specific conductance, silicon, and sodium; and (D) sulfate, total dissolved nitrogen, total phosphorous, total suspended solids, and turbidity measured at intensive and gradient sites in the Upper Delaware River (UPDE) drainage basin, water years 2006 and 2007.—Continued
14 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

streamwater acidification, especially during spring high flow; 

low pH and ANC values are associated with the high nitrate 

levels (Murdoch and Stoddard, 1992). All of these forested 

basins threatened with nitrate impairment showed signs of 

episodic acidification during spring snowmelt: elevated levels 

of nitrate, low pH, and low ANC. Spring high-flow ANC 

values were as much as 50 percent lower than median annual 

values for the intensive sites and as much as 50 to 70 percent 

lower than summer base-flow values for the survey sites.

Nitrate concentrations in the other eutrophic basins, as 

well as the mesotrophic basins, were most likely affected 

by both agricultural runoff and long-term acid deposition. 

Substantial portions of the Callicoon Creek and West Branch 

Delaware River Basins were in agricultural production, and 

median levels of nitrate, ANC, and pH in these streams during 

the study period were higher than in the forested intensive 

and gradient site streams. The mainstem of the Delaware 

River was eutrophic with respect to nitrate from the northern 

boundary of the UPDE downstream to Pond Eddy, where it 

returned to mesotrophic status.

The basins assessed as mesotrophic with respect to 

total phosphorous included those with large percentages 

of agricultural land use as well as those with greater than 

90 percent forest cover, with the exception of the East 

Branch Delaware River, which was classified as oligotrophic. 

The contribution of water from the East Branch Delaware 

River with low concentrations of total phosphorous kept the 

mainstem in an oligotrophic condition until the confluence 

with Callicoon Creek, where the mainstem became 

mesotrophic. The eutrophic threshold for total phosphorous 

was not exceeded in any of the basins.

Median concentrations of total dissolved nitrogen at 

all of the mainstem Delaware River sites as well as those on 

the East Branch and West Branch Delaware River, Callicoon 

Creek, and Calkins Creek exceeded the USEPA ecoregional 

reference condition. Median concentrations at all of the 

intensive and gradient study sites, with the exception of the 

East Branch Delaware River, the Delaware River at Callicoon, 

and the Delaware River at Barryville, exceeded the USEPA 

ecoregional reference condition for total phosphorous.

Tiered Monitoring Strategy 

Water-Quality Results

The water-quality results from the tiered monitoring 

strategy can be described using cumulative curves. Cumulative 

curves can yield valuable information about regional and sitespecific water-quality conditions. The position of the curve in 

relation to reference-site curves or water-quality thresholds 

can indicate the frequency of samples or the percentage of the 

basin area that exceeds these reference curves and guidelines. 

The shape of the curve can indicate whether the minimum or 

maximum values (or both) are above the level of a reference 

curve or threshold. By plotting curves of data, such as those 

Table 5. Values of selected common constituents and properties for original Scenic Rivers Monitoring Program (SRMP) water quality 

(Delaware River Basin Commission, 2008b), existing main stem Delaware River water quality, nutrient criteria (Smith and others, 2006), 

and U.S. Environmental Protection Agency (USEPA) ecoregional reference conditions.

[mg/L, milligrams per Liter; μS/cm, microsiemens per centimeter in 25 degrees Celsius; NA, not available]

Constituent or property SRMP 

water quality1

Existing 

water quality2

Nutrient 

criteria3

USEPA ecoregional 

reference condition4

Ammonia + ammonium (mg/L) 0.022 0.028 NA NA

Conductivity (μS/cm) 68 66.9 NA NA

Nitrate + nitrite (mg/L) 0.293 1.15 0.24, 0.98 0.38

Total nitrogen (mg/L) 0.202 0.42 NA NA

Total phosphorous (mg/L) 0.029 0.01 0.0175, 0.065 0.01

Total suspended solids (mg/L) 4 29 NA NA

1 Mean values of original SRMP data set used for reachwide regulations. 

2 Median values of data collected by U.S. Geological Survey during water years 2006 and 2007 (median values are shown here because the new Special Protection Waters regulations are to be based on median values; reach-wide main stem values are shown here for comparison to SRMP values). 

3 Nutrient criteria of Smith and others (2006): oligotrophic-mesotrophic nutrient condition boundary, mesotrophic-eutrophic nutrient condition boundary 

(threatened with impairment).

4 USEPA Ecoregion VIII ecoregional reference condition.
Tiered Monitoring Strategy Water-Quality Results 15

Figure 5. Classifications of water quality with respect to nitrate concentration in the Upper Delaware River (UPDE) 

tributary basins, water years 2006 and 2007. (Concentrations are median values at each monitoring location; classification 

ranges are those suggested by Smith and others, 2006; mg/L, milligrams per liter).

#

#

# # #

Lac

# kawaxen River

West Branch Delaware River

East Branc h De laware River

0 10

0 10 20 KILOMETERS

20 MILES

75°30' 75° 74°30'

42°30'

42°

41°30'

Calkins Creek

Callicoon Creek

Mongaup River

 West 

Colang Creek

 Twin

Lakes Creek

Halfway 

 Brook

 Mill 

Brook

Port Jervis

80° 75°

45°

40°

UPDE

Basin

Pennsylvania

New York

New Jersey

Shingle 

Kill

Shahola Creek

Masthope 

 Creek

Beaver 

 Brook

Ten Mile 

 Creek

 Grassy

Swamp Creek

Beaver Dam Creek

Hollister Creek

Equinunk Creek

Cooley Creek

Little Equinunk Creek

 Hankins 

Creek

Basket 

 Creek

Hoolihan Brook

Pea Brook

Bouchoux Brook

Humphries Brook

 Shingle

Hollow Creek

Eutrophic (greater than 0.98 milligrams per liter)

Mesotrophic (0.24 to 0.98 milligrams per liter)

Oligotrophic (less than 0.24 milligrams per liter)

Base from U.S. Geological Survey 1:24,000 digital raster graphic, North American Datum 1983, 

Universal Transverse Mercator Projection, Zone 18.

Tributary watershed

Mainstem intensive sites

Tributary intensive sites

Tributary gradient sites

Tributary regional survey sites

Upper Delaware administrative boundary

EXPLANATION

Upper Delaware drainage basin
16 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

Figure 6. Classifications of water quality with respect to total phosphorous concentration in the Upper Delaware River 

(UPDE) tributary basins, water years 2006 and 2007. (Concentrations are median values at each monitoring location; 

classification ranges are those suggested by Smith and others, 2006; mg/L, milligrams per liter).

#

#

# # #

#

75°30' 75° 74°30'

42°30'

42°

41°30'

West Branch Delaware River

Calkins Creek

East Branch Delaware River

Callicoon Creek

Mongaup River

Lackawaxen River

 West 

Colang Creek

 Twin

Lakes Creek

Halfway 

 Brook

 Mill 

Brook

Port Jervis

80° 75°

45°

40°

UPDE

Basin

Pennsylvania

New York

New Jersey

Base from U.S. Geological Survey 1:24,000 digital raster graphic, North American Datum 1983, 

Universal Transverse Mercator Projection, Zone 18.

Eutrophic (greater than 0.065 milligrams per liter)

Mesotrophic (0.0175 to 0.065 milligrams per liter)

Oligotrophic (less than 0.24 milligrams per liter)

Tributary watershed

Mainstem intensive sites

Tributary intensive sites

Tributary gradient sites

Upper Delaware administrative boundary

EXPLANATION

Upper Delaware drainage basin

0 10

0 10 20 KILOMETERS

20 MILES
Tiered Monitoring Strategy Water-Quality Results 17

of the seasonal stream surveys, from successive years, trends 

in the quality of the water in the whole population of streams 

over time can be identified from shifts in the curve’s shape 

and location. Similarly, seasonal shifts can be identified 

by comparing plots from different seasons. If cumulative 

curves from different time periods are compared, improving 

water-quality conditions with respect to constituents such as 

nutrients would be indicated by a shift to the left over time, 

whereas a shift to the right would represent degradation of 

water quality. This convention is reversed for pH and ANC, 

where a shift of the curve to the right, representing an increase 

in pH or ANC, would be considered an improvement in 

water quality. 

Three types of cumulative curves were created to 

describe the existing water-quality conditions in the UPDE: 

regional, site-specific, and spatial-temporal. The characteristics 

of these curves and their interpretations are discussed below.

Regional Stream Surveys

Stream surveys allow for the extension of data collected 

at intensively sampled sites to a regional scale, which is 

advantageous because sampling every stream in a basin 

is typically cost prohibitive or physically impossible. The 

use of probability surveys negates the bias of judgment or 

convenience sampling (Olsen and others, 1999). In this study, 

the number of tributaries was small enough that all major 

tributaries in the study area could be sampled during regional 

stream surveys.

The regional stream-survey cumulative curves describe 

the water-quality condition of the entire basin, and can be 

integrated with data from the intensively sampled sites. By 

plotting data from successive stream surveys, trends in the 

quality of water in the whole population of streams over time 

can be identified from shifts in the curves’ shape and location. 

Similarly, seasonal shifts can be identified by plotting the 

results of surveys from different seasons. 

The regional cumulative curves shown in figure 7 

describe the percentage of the basin at or below different 

concentrations by focusing on the data collected during spring 

high-flow and summer base-flow surveys during the 2006 and 

2007 water years. The x-axis shows concentration and the 

y-axis shows the cumulative percentage of the basin area in 

which the concentration was at or below a given value. Also 

shown are box plots of data collected at the gradient sites over 

the course of this study. The box plots for the gradient sites 

are plotted at the same y-axis position as the corresponding 

stream-survey site point.

Figure 7 allows for comparisons of results between 

stream surveys and shows the integration of the regional and 

site-specific data using nitrate concentrations as an example. 

By plotting the cumulative curves of the survey data and 

the box plots of the gradient sites together, the regional and 

site-specific data become more meaningful. This combination 

places the survey data in the context of the overall annual 

variability and describes how the data from the gradient 

sites relate to the regional data. Nitrate concentrations 

from both summer low-flow surveys and the spring 2006 

high-flow survey tend to plot in the lower percentiles of the 

concentrations from the intensively sampled gradient sites, 

whereas the spring 2007 high-flow survey data plot in the 

upper percentiles, as shown by the integration of the box 

plots with the cumulative curves. The spacing of the box plots 

along the survey cumulative curves shows that the gradient 

sites are representative of the water-quality conditions found 

throughout the basin.

The plots in figure 7 show year-to-year and seasonal 

shifts in nitrate concentration. The results of a Wilcoxon 

one-sided test indicate that nitrate concentrations were greater 

during the 2007 spring high-flow (p = 0.019) and summer 

base-flow (p < 0.001) surveys than during the 2006 spring 

high-flow and summer base-flow surveys, respectively, 

and were greater during the spring 2006 high-flow survey 

(p = 0.0066) than during the summer 2006 base-flow survey. 

The percentage of basin area in which the eutrophic threshold 

for nitrate was exceeded was approximately 55 percent 

during the 2006 spring high-flow survey and approximately 

65 percent during the 2007 spring high-flow survey. The 

regional curves describe the overall quality of water in the 

basin and could be used as a management tool to determine 

whether it is improving or degrading over time. This 

regional analysis would not be possible with a monitoring 

strategy in which water-quality data are collected at only a 

modest number of fixed sites and, without the data from the 

intensively sampled sites, the temporal context of the surveys 

would be lost. 

Gradient and Intensive Site Networks

Cumulative curves describing the water-quality results 

for the gradient and intensive sites were created for five 

common constituents and properties of interest: pH, nitrate, 

specific conductance, total phosphorous, and total suspended 

solids. Each of these cumulative plots is shown with waterquality thresholds (Smith and others, 2006) and curves 

representing conditions at reference sites and gradient sites for 

comparison. The reference sites chosen were those intensive 

and gradient sites with drainage basins that had greater than 

80 percent forest cover, less than 8 percent suburbanization, 

and median specific-conductance values less than 150 μS/cm 

(Smith and others, in press).

The cumulative curves in figure 8 were plotted by 

combining the data from gradient and intensive sites within 

each land-use class. Because the reference curves were created 

using the data from the forested sites, the reference-site and 

forested-site curves are identical. These plots show the effects 

of land use on water quality, which land use is most frequently 

associated with exceedance of water-quality thresholds, and 

the relation of different land uses to reference curves. These 

plots demonstrate which land use has the greatest potential 
18 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

A B

1.0

0.8

0.6

0.4

0.2

0

0 1.0 2.0 3.0 4.0 0 1.0 2.0 3.0 4.0

CUMULATIVE FRACTION OF BASIN AREA

NITRATE CONCENTRATION, IN MILLIGRAMS PER LITER

1.0

0.8

0.6

0.4

0.2

0

C D

EXPLANATION

Mesotrophic - eutrophic boundary

Oligotrophic - mesotrophic boundary

Stream survey

10th percentile

25th percentile

Median

75th percentile

90th percentile

Figure 7. Regional cumulative curves of basin area ranked by increasing nitrate concentration for (A) spring 2006 high flow, 

(B) summer 2006 base flow, (C) spring 2007 high flow, and (D) summer 2007 base flow with box plots for selected gradient sites 

for the Upper Delaware River (UPDE) tributaries. (Trophic boundaries from Smith and others, 2006.)
Tiered Monitoring Strategy Water-Quality Results 19

to degrade water quality. For example, nitrate concentrations 

in 75 percent of the samples from agricultural sites were 

higher than the nitrate eutrophic threshold, whereas those 

in 40 percent of the samples from forested sites were above 

this threshold. Therefore, with respect to nitrate, the primary 

concern for potential impairment of water quality in the 

UPDE is agricultural runoff; a secondary concern is the longterm effects of acid deposition in forested basins. Values of 

pH and total suspended solids concentrations were higher 

at agricultural sites than at sites in other land uses and the 

reference sites.

Site-specific cumulative curves for gradient and intensive 

sites grouped by land use are shown in figures 9 to 11. 

The site-specific plots display the frequency of occurrence 

of samples in which concentrations exceed water-quality 

thresholds and reference curves. Figure 9 shows that more 

than 90 percent of the samples collected at both Callicoon 

Creek and West Branch Delaware River exceeded the 

water-quality threshold for nitrate and were approximately 

1 mg/L higher than the reference curve for most cumulative 

frequencies. The total phosphorous threshold was exceeded in 

0 to 10 percent of the samples from the agricultural sites. Total 

suspended solids concentrations were highest in samples from 

Callicoon Creek and West Branch Delaware River for most 

cumulative frequencies. pH was higher than the reference 

curve for most cumulative frequencies at all of the agricultural 

sites. Callicoon Creek was the only agricultural site at 

which specific conductance was consistently higher than the 

reference curve (fig. 9).

Nitrate concentrations in 75 percent of the samples from 

the East Branch Delaware River were greater than the nitrate 

threshold for eutrophic impairment (fig. 10). It is apparent 

from figure 10 that the water-quality signature at the East 

Branch Delaware River was different from those at the sites in 

the smaller forested basins (Halfway Brook, Mill Brook, and 

Mongaup River); concentrations of nitrate, total phosphorous, 

and total suspended solids at the East Branch Delaware River 

were generally higher for most cumulative frequencies, 

0

0.2

0.4

0.6

0.8

1.0

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0

TOTAL PHOSPHOROUS CONCENTRATION,

IN MILLIGRAMS PER LITER

0.001

pH, IN STANDARD UNITS

6.0 7.0

CUMULATIVE FREQUENCY

1.0

0.8

0.6

0.4

0.2

0 0 100 10

EXPLANATION

Mesotrophic-eutrophic boundary

Oligotrophic-mesotrophic boundary

Reference sites

Gradient sites

Forested sites

Agricultural sites

Suburban sites

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

TOTAL SUSPENDED SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

1 2 3 4 5 6 0.01 0.1 1 10 5.5 6.5 7.5 8.0

50 150 200 250 1 100 1,000 10,000

CUMULATIVE FREQUENCY

Figure 8. Cumulative frequency curves of nitrate concentration, total phosphorous concentration, pH, specific conductance, and 

total suspended solids concentration for different land uses in the Upper Delaware River (UPDE) drainage basin. (Trophic boundaries 

from Smith and others, 2006; drainage basins of reference sites are greater than 80 percent forested and less than 8 percent 

suburbanized, and have associated specific-conductance values less than 150 microsiemens per centimeter; gradient sites represent 

the range of land uses found in the basin.)
20 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

whereas specific conductance was generally lower (fig. 10). 

This finding could be the result of the difference in drainagebasin size, the presence of pockets of agriculture and small 

towns in the basin, and (or) the extreme storm events that 

occurred during the study period.

Of the samples from West Colang Creek and Twin 

Lakes Creek, less than 5 percent contained nitrate or total 

phosphorous at concentrations that exceeded the eutrophic 

threshold, and none had values for nitrate, pH, specific 

conductance, or total suspended solids that exceeded those 

at the reference sites (fig. 11). As previously mentioned, it 

is possible that the basins draining to these sites have not 

reached a critical threshold of suburbanization at which 

water-quality degradation would become apparent. Total 

phosphorous concentrations at West Colang Creek and Twin 

Lakes Creek, however, were slightly greater than most of the 

concentrations on the total phosphorous reference curve at 

equal cumulative frequencies. 

An example of a spatial-temporal cumulative curve 

for nitrate and total phosphorous is shown in figure 12. 

This cumulative curve is based on a method modified from 

the Chesapeake Bay Program (Chesapeake Bay Program 

Scientific, Technical and Advisory Committee, 2006). This 

cumulative curve depicts the frequency at which the nitrate 

and total phosphorous thresholds for impairment were 

exceeded for given percentages of the UPDE Basin. The 

curve was created by calculating the percentage of the basin 

in which concentrations were greater than the eutrophic 

threshold for each monthly gradient-site sampling trip during 

the study period. These spatial percentages were then ranked 

from largest to smallest, and the cumulative frequency of 

each was plotted. A spatial-temporal curve depicting highquality waters would plot along the y-axis, passing very 

close to the origin, and then along the x-axis (fig. 12). This 

ideal curve could be changed to depict desired conditions 

by adjusting the relation between the desired percentage 

of basin area and the corresponding percentage of time 

during which samples contained concentrations less than the 

eutrophic threshold. The plot in figure 12 shows that nitrate 

concentrations in 60 percent of the basin were greater than the 

CUMULATIVE FREQUENCY

0

0.2

0.4

0.6

0.8

1.0

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0

TOTAL PHOSPHOROUS CONCENTRATION,

IN MILLIGRAMS PER LITER

0.001

pH, IN STANDARD UNITS

6.0 7.0

1.0

0.8

0.6

0.4

0.2

0

0 100 10

EXPLANATION

Mesotrophic - eutrophic boundary

Oligotrophic - mesotrophic boundary

Reference sites

Gradient sites

Callicoon Creek

Calkins Creek

Lackawaxen River

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

TOTAL SUSPENDED SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

1 2 3 4 5 6 0.01 0.1 1 10 5.5 6.5 7.5 8.0

50 150 200 250 1 100 1,000 10,000

CUMULATIVE FREQUENCY

West Branch Delaware River at Hale Eddy

100,000

Figure 9. Site-specific cumulative frequency curves of nitrate concentration, total phosphorous concentration, pH, specific 

conductance, and total suspended solids concentration for agricultural sites in the Upper Delaware River (UPDE) drainage basin. 

(Trophic boundaries from Smith and others, 2006; drainage basins of reference sites are greater than 80 percent forested and 

less than 8 percent suburbanized, and have associated specific-conductance values less than 150 microsiemens per centimeter; 

gradient sites represent the range of land uses found in the basin.)
Tiered Monitoring Strategy Water-Quality Results 21

nitrate water-quality threshold approximately 50 percent of 

the time. Improving water quality would be indicated by the 

curve shifting closer to the origin (Chesapeake Bay Program 

Scientific, Technical and Advisory Committee, 2006). The 

spatial-temporal cumulative curve can be used as a tool for 

maintaining or improving water-quality conditions while 

acknowledging the likelihood that 100 percent of the basin 

will not be at reference conditions or below water-quality 

thresholds 100 percent of the time. 

Continued use of the tiered monitoring strategy in the 

future with sampling conducted year round would allow for 

robust future assessments of water quality and detection of 

changes in water quality over time. Sampling year round 

is important, as sampling only during the growing season 

does not capture the spring snowmelt runoff or the highflow storm events that occur during the late fall and winter 

months. Stormflow sampling is also important, as storm events 

typically move large quantities of sediment, and may contain 

high concentrations and result in large yields of nutrients 

and major ions. For example, the plots of particulate organic 

carbon, total suspended solids, and turbidity shown in figure 4 

indicate that the median and maximum values were higher 

at the intensive sites, where samples were collected during 

storms, than at the sites that were only sampled monthly. 

The results of a Wilcoxon statistical test (Helsel and Hirsch, 

1992) show that the results obtained by sampling only during 

the growing season can be different for some constituents 

(aluminum, nitrate, silicon, total dissolved nitrogen) than those 

obtained with the strategy used in this study. For example, the 

median concentration of total suspended solids at Callicoon 

Creek was 27 mg/L if sampling was conducted throughout the 

year and during storms, and 2 mg/L if sampling was conducted 

only during the growing season. Similar results were found for 

other sites and constiuents.

Intensive monitoring at the upper and lower bounds of 

the UPDE, one or two intermediate sites along the mainstem 

of the Delaware River between the upper and lower bounds, 

and key tributaries such as the Lackawaxen River and 

Callicoon Creek would allow for detection of changes in 

concentration-discharge relations as well as capture peak 

CUMULATIVE FREQUENCY

0

0.2

0.4

0.6

0.8

1.0

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0

TOTAL PHOSPHOROUS CONCENTRATION,

IN MILLIGRAMS PER LITER

0.001

pH, IN STANDARD UNITS

6.0 7.0

1.0

0.8

0.6

0.4

0.2

0

0 100 10

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

TOTAL SUSPENDED SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

1 2 3 4 5 6 0.01 0.1 1 10 5.5 6.5 7.5 8.0

50 150 200 250 1 100 1,000 10,000

CUMULATIVE FREQUENCY

EXPLANATION

Mesotrophic - eutrophic boundary

Oligotrophic - mesotrophic boundary

Reference sites

Gradient sites

Halfway Brook

Mill Brook

Mongaup River

East Branch Delaware River at Fishs Eddy

Figure 10. Site-specific cumulative frequency curves of nitrate concentration, total phosphorous concentration, pH, specific 

conductance, and total suspended solids concentration for forested sites in the Upper Delaware River (UPDE) drainage basin. 

(Trophic boundaries from Smith and others, 2006; drainage basins of reference sites are greater than 80 percent forested and less 

than 8 percent suburbanized, and have associated specific-conductance values less than 150 microsiemens per centimeter; gradient

sites represent the range of land uses found in the basin.)
22 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania CUMULATIVE FREQUENCY

0

0.2

0.4

0.6

0.8

1.0

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0

TOTAL PHOSPHOROUS CONCENTRATION,

IN MILLIGRAMS PER LITER

0.001

pH, IN STANDARD UNITS

6.0 7.0

1.0

0.8

0.6

0.4

0.2

0

0 100 10

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

TOTAL SUSPENDED SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

1 2 3 4 5 6 0.01 0.1 1 10 5.5 6.5 7.5 8.0

50 150 200 250 1 100 1,000 10,000

CUMULATIVE FREQUENCY

EXPLANATION

Mesotrophic - eutrophic boundary

Oligotrophic - mesotrophic boundary

Reference sites

Gradient sites

Halfway Brook

Mill Brook

Mongaup River

East Branch Delaware River at Fishs Eddy

Figure 12. Spatial-temporal cumulative curves for nitrate and total 

phosphorous concentrations in the Upper Delaware River (UPDE) 

drainage basin and an example theorized ideal curve.

Figure 11. Site-specific cumulative frequency curves of nitrate concentration, total phosphorous concentration, pH, specific 

conductance, and total suspended solids concentration for suburbanized sites in the Upper Delaware River (UPDE) drainage basin. 

(Trophic boundaries from Smith and others, 2006; drainage basins of reference sites are greater than 80 percent forested and 

less than 8 percent suburbanized, and have associated specific-conductance values less than 150 microsiemens per centimeter; 

gradient sites represent the range of land uses found in the basin.) CUMULATIVE FRACTION OF TIME

SPATIAL FRACTION OF

UPPER DELAWARE RIVER BASIN

WITH NUTRIENT CONCENTRATIONS GREATER

THAN WATER-QUALITY THRESHOLD

0

0

0.2

0.2

0.4

0.4

0.6

0.6 0.8

0.8

1.0

1.0

EXPLANATION

Total phosphorous

Nitrate

Example ideal curve
Summary 23

concentrations during high flows. A Kruskal-Wallis test 

(Helsel and Hirsch, 1992) applied to the mainstem data 

(Delaware River at Callicoon, Delaware River near Barryville, 

and Delaware River at Port Jervis) showed a significant 

difference (p < 0.05) in median values for some constituents 

and properties (chloride, dissolved organic carbon, nitrate, 

specific conductance, sodium, sulfate, total dissolved nitrogen, 

total suspended solids, and turbidity) between sites; therefore, 

maintaining at least one of the intermediate sites would allow 

for tracking changes in mainstem water quality.

Sampling at gradient study sites that represent a range 

of land uses would allow for water-quality monitoring at 

additional sites without incurring the cost of maintaining 

the intensive sites and would allow water-quality/land-use 

relations to be monitored. Continuing to monitor at the 

monthly sites used in this study would allow for building 

upon the existing data set. If results of future stream surveys 

show substantial changes in concentrations at certain sites 

or if remote sensing of land use shows changes in basin 

characteristics, changing the location of some of the gradient 

sites could be considered.

Annual high-flow and low-flow stream surveys allow for 

an assessment of the basin as a whole, and, when combined 

with the intensive-site and gradient-site data, improve the 

understanding of the ecosystem and allow science-based 

management decisions to be made. Sampling rotating groups 

of randomly selected tributaries such that the entire population 

of streams is sampled every 3 years would reduce the cost of 

individual surveys while still yielding unbiased results that 

could be extrapolated across the entire basin.

Chemical and Total Suspended 

Solids Yields

Annual yields for the dissolved analytes sampled during 

the 2006 and 2007 water years are listed in appendix 3. Yields 

for total suspended solids are given only for water year 2007; 

during water year 2006, total suspended solids were measured 

only during storm events.

The regional flood of June 2006 moved large quantities 

of both particulate and dissolved constituents through the 

UPDE. The East Branch and West Branch Delaware River 

delivered an estimated minimum of 2,214 kg/ha (449,000 Mg) 

and 144 kg/ha (22,200 Mg) of total suspended solids to 

the Delaware River, respectively. More than 874 kg/ha 

(696,000 Mg) of total suspended solids were exported from 

the UPDE Basin during this flood event. (These estimates are 

minimums because of incomplete sampling over the entire 

storm hydrograph.) Sampling for total suspended solids prior 

to the flood was inadequate to determine the percentage of the 

annual load contributed by this storm. 

The flash flood that occurred in the headwaters of 

the East Branch Delaware River in June 2007 contributed 

27,000 Mg of total suspended solids, 816 Mg of particulate 

organic carbon, 9.98 Mg of total phosphorous, and 30.8 Mg 

of nitrate to the Delaware River. The difference in loads at 

the East Branch site and the Delaware River at Callicoon 

site indicates 11,100 Mg of solids were deposited in the 

river between the East Branch site and the Delaware River 

at Callicoon site by the time 95 percent of the stormflow had 

passed the Delaware River at Callicoon site. These sediments 

are likely to be re-suspended by future stormflows.

Nitrate yields at most of the intensive sites were higher 

during water year 2007 than during water year 2006, whereas 

yields of major ions, dissolved organic carbon, sulfate, and 

aluminum were all lower during water year 2007 than during 

water year 2006. A comparison of yields between the East 

Branch and West Branch Delaware River showed that the West 

Branch had higher yields of nitrate, major ions, and sulfate 

during both water years 2006 and 2007. Yields of nitrate, 

major ions, and sulfate along the mainstem of the Delaware 

River tended to increase downstream between Callicoon and 

Barryville, then decrease between Barryville and Port Jervis. 

Yields of dissolved organic carbon increased and yields of 

total suspended solids decreased from Callicoon to Barryville 

and from Barryville to Port Jervis. 

Yields of nitrate, major ions, sulfate, dissolved organic 

carbon, and total suspended solids at Callicoon Creek, in an 

agricultural watershed, were nearly twice those at the other 

intensive sites during water year 2006. Yields of all these 

constituents and properties were lower during water year 2007 

at Callicoon Creek, but were higher than those at any other 

intensive site.

Summary

Water-quality samples were collected from the Upper 

Delaware Scenic and Recreational River and its tributaries 

during water years 2006 and 2007 to document existing 

water quality, determine relations between land use and water 

quality, and identify areas of water-quality concern. A tiered 

water-quality monitoring framework was used in this study, 

with the tiers consisting of intensively sampled sites, gradient 

sites representing the range of land uses present in the basin, 

and regional stream-survey sites.

The percentage of agricultural land use in a basin was 

found to be positively correlated with ANC and concentrations 

of calcium, potassium, nitrate, total dissolved nitrogen, and 

dissolved phosphorous. Streams in agricultural basins had the 

highest median concentrations, greatest ranges, and largest 

yields of nutrients. No correlations were found between 

suburbanization and water quality. It is possible that the level 

of suburbanization in the UPDE has not yet reached a critical 

threshold, beyond which degradation of water quality would 

be observed.

Maps showing water-quality classifications with respect 

to nutrients indicate that a large portion of the UPDE Basin 

ranged from mesotrophic to eutrophic with respect to nitrate. 
24 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

Nitrate concentrations in samples from the mainstem Delaware 

River exceeded the threshold for potential impairment with 

respect to nitrate from Hancock downstream to Pond Eddy. All 

of the intensive and gradient study sites were mesotrophic with 

respect to total phosphorous, with the exception of the East 

Branch Delaware River and the mainstem of the Delaware 

River from Hancock to Callicoon, which were oligotrophic.

Cumulative curves for the UPDE yielded valuable 

information about regional and site-specific water quality 

that would not have been available if the monitoring program 

had been limited to sampling of boundary control points 

only. The position of the curves in relation to reference-site 

curves or water-quality thresholds indicated the frequency 

of occurrence of samples or the percentage of basin area 

in which the value indicated by these curves or thresholds 

was exceeded. The regional cumulative curves indicated 

that 55 to 65 percent of the basin was beyond the eutrophic 

threshold in terms of nitrate during the spring high-flow 

surveys, and 25 to 60 percent of the basin was beyond the 

eutrophic threshold in terms of nitrate during the summer 

base-flow surveys. Land-use cumulative curves indicated 

that nitrate concentrations in 75 percent of samples from 

agricultural basins and 40 percent of samples from forested 

basins exceeded the eutrophic threshold for nitrate. The sitespecific cumulative curves indicated that nitrate concentrations 

in more than 90 percent of samples from Callicoon Creek and 

the West Branch Delaware River, both in basins with high 

percentages of agricultural land use, exceeded the eutrophic 

threshold for nitrate. The cumulative curves of existing water 

quality presented in this report can be used as a benchmark 

with which future cumulative curves can be compared in 

order to determine whether the water quality of the UPDE is 

improving, static, or degrading. 

The tiered monitoring approach used in this study 

met the study objective of assessing the existing quality 

of water in the tributaries to and mainstem of the UPDE. 

This monitoring approach allowed the integration of sitespecific data with regional data, improving the understanding 

of the ecosystem and providing a basis for science-based 

management decisions. 

Acknowledgments

 The authors thank Don Hamilton and Jamie Meyer of 

the NPS Resource Monitoring Staff of the UPDE for their 

assistance with field work and the valuable knowledge of the 

UPDE they provided, and the staff at the USGS laboratory in 

Troy, NY, for chemical analyses. 

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Biotic Index (NBI) for use with benthic macroinvertebrate 

communities: Ecological Indicators, v. 7, p. 371–386.

Smith, A.J., Heitzman, D.L., Abele, L.E., Duffy, B., and 

Novak, M.A., in press, Standard operating procedures: 

Biological monitoring of surface waters: Albany, N.Y., New 

York State Department of Environmental Conservation, 

Division of Water Resources. 

Stoddard, J.L., 1994, Long-term changes in watershed 

retention of nitrogen: Its causes and aquatic consequences, 

in Baker, L.A., ed., Environmental chemistry of lakes and 

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

Advances in Chemistry Series, v. 237, p. 223–284. 

Suro, T.P., Firda, G.D., and Szabo, C.O., 2009, Flood of June 

26–29, 2006, Mohawk, Delaware, and Susquehanna River 

Basins, New York: U.S. Geological Survey Open-File 

Report 2009–1063, 97 p.

U.S. Census Bureau, 2008, accessed January 20, 2008, at 

http://www.census.gov/index.html.

U.S. Environmental Protection Agency, 2001, Ambient 

water quality criteria recommendations: Information 

supporting the development of State and Tribal nutrient 

criteria—Rivers and streams in nutrient Ecoregion 

VIII: U.S. Environmental Protection Agency, Office of 

Water, EPA-822–B–01–015, December 2001, 28 p. plus 

app., accessed August 8, 2008, at http://www.epa.gov/

waterscience/criteria/nutrient/ecoregions/rivers/rivers_8.pdf.

U.S. Geological Survey, 2006, Collection of water samples, 

v. 2.0: U.S. Geological Survey Techniques of WaterResources Investigations, book 9, chap. A4, September, 

accessed September 17, 2009, at http://pubs.water.usgs.gov/

twri9A4/.
This page has been left blank intentionally.
Appendix 1 27

Appendix 1. Land Use in Drainage Areas of Sites Sampled during the Upper 

Delaware River (UPDE) Study.

Table 1–1. List of sites with drainage area and land-use percentages.—Continued

[km2, square kilometers; land-use values in percent]

U.S. Geological Survey streamgage and number

Drainage 

area 

(km2

)

Land use

Forested Agriculture Suburbanized

Basket Creek at mouth near Long Eddy, NY (0142728005) 58 92 6 2

Beaver Brook at mouth near Barryville, NY (0143215005) 61 95 2 2

Beaverdam Creek at mouth at Damascus, PA (0142760005) 27 76 18 6

Bouchoux Brook at mouth near Lordville, NY (0142723005) 13 87 5 6

Calkins Creek at mouth at Milanville, PA (0142770105) 116 67 28 4

Callicoon Creek at Callicoon, NY (01427500) 287 66 29 5

Cooley Creek at mouth near Stalker, PA (0142730505) 8 95 2 3

Delaware River above Lackawaxen River near Barryville, NY (01428500) 5,242 82 13 3

Delaware River at Callicoon, NY (01427510) 4,725 82 13 3

Delaware River at Lordville, NY (01427207) 4,118 83 12 3

Delaware River at Narrowsburg, NY (01427750) 4,957 82 13 3

Delaware River at Pond Eddy, NY (01432805) 7,312 82 13 4

Delaware River at Port Jervis, NY (01434000) 7,961 82 12 5

Delaware River below mouth of Mongaup River, NY (0143351103) 7,938 82 12 5

East Branch Callicoon Creek at mouth at Hortonville, NY (0142744205) 192 65 30 5

East Branch Delaware River at Fishs Eddy, NY (01421000) 2,028 90 6 3

Equinunk Creek near Equinunk, PA (01427200) 149 80 14 4

Grassy Swamp Brook near Tusten, NY 10 96 0 2

Halfway Brook at Barryville NY (01432180) 69 95 1 3

Hankins Creek at Hankins, NY (01427350) 41 84 12 4

Hollister Creek near Abrahamsville, PA (01427400) 24 70 24 5

Hoolihan Brook at Long Eddy, NY (01427260) 12 97 2 1

Humphries Brook at mouth at Lordville, NY (0142720505) 7 95 1 3

Lackawaxen River at Hawley, PA (01432110) 532 65 26 7

Lackawaxen River at Rowland, PA (01432110) 1,526 76 15 7

Little Equinunk Creek at Stalker, PA (01427300) 65 79 13 6

Masthope Creek at Masthope, PA (01428200) 79 84 12 4

Middle Creek near Hawley, PA (01431000) 209 74 20 5

Mill Brook at mouth at Pond Eddy, NY (0143280005) 52 94 1 4

Mongaup River near Mongaup, NY (01433500) 539 86 6 7
28 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania

Table 1–1. List of sites with drainage area and land-use percentages.—Continued

[km2, square kilometers; land-use values in percent]

U.S. Geological Survey streamgage and number

Drainage 

area 

(km2

)

Land use

Forested Agriculture Suburbanized

North Branch Callicoon Creek at mouth at Hortonville, NY (0142749205) 93 69 27 4

Pea Brook at Long Eddy, NY (01427250) 17 89 6 5

Shehawken Creek at Starlight, PA (01427100) 41 77 17 5

Shingle Hollow Creek near Starlight, PA 3 100 0 0

Shingle Kill at Sparrow Bush, NY (01433600) 33 96 0 3

Shohola Creek near Shahola, PA (01432500) 218 91 1 7

Ten Mile River at mouth at Tusten, NY (0142800003) 127 85 11 3

Twin Lakes Creek near Shohola, PA (01432600) 29 87 1 11

West Branch Delaware River at Hale Eddy, NY (01426500) 1,540 73 21 4

West Colang Creek at West Colang, PA (0142848005) 12 81 0 17
Appendix 2 29

Appendix 2. Water-Quality Statistics for the Intensive and Gradient Study 

Sites, Upper Delaware River Basin, October 2005 to September 2007.

Index

U.S. Geological Survey streamgage and number Table

Callicoon Creek at Callicoon, NY (01427500) 2–1

Calkins Creek at mouth at Milanville, PA (0142770105) 2–2

Halfway Brook at Barryville, NY (01432180) 2–3

Lackawaxen River at Rowland, PA (01432110) 2–4

Mill Brook at mouth at Pond Eddy, NY (0143280005) 2–5

Mongaup River near Mongaup, NY (01433500) 2–6

Twin Lakes Creek near Shohola, PA (01432600) 2–7

West Colang Creek at West Colang, PA (0142848005) 2–8

East Branch Delaware River at Fishs Eddy, NY (01421000) 2–9

West Branch Delaware River at Hale Eddy, NY (01426500) 2–10

Delaware River at Callicoon, NY (01427510) 2–11

Delaware River above Lackawaxen River near Barryville, NY (01428500) 2–12

Delaware River at Port Jervis, NY (01434000) 2–13
30 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–1. Water-Quality Statistics of Callicoon Creek at Callicoon, NY (01427500). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 8.27 10.62 11.32 13.85 14.90 19.02 26.11 44 0 Ammonium 0.00 0.01 NA 0.03 0.05 0.09 0.43 44 22 Chloride 8.75 10.97 12.16 14.57 17.30 18.10 22.84 43 0 Dissolved organic carbon 1.71 1.93 2.07 2.98 3.46 3.84 4.92 44 0 Aluminum 0.008 0.013 NA 0.023 0.029 0.037 0.056 44 24 Boron 0.001 0.002 NA 0.004 NA 0.008 0.013 44 37 Calcium 5.18 6.12 6.41 7.06 7.90 9.60 10.90 44 0 Magnesium 0.95 1.07 1.16 1.28 1.42 1.61 1.83 44 0 Potassium 1.09 1.20 1.32 1.48 1.67 1.86 2.66 44 0 Silicon 0.53 0.71 0.82 1.06 1.20 1.32 1.54 44 0 Sodium 4.74 5.94 6.66 8.05 9.32 10.03 11.33 44 0 Nitrate (as NO3

) 1.18 1.60 1.84 2.17 2.53 2.78 3.30 43 0

Particulate organic carbon 1 1 1 5 6 16 25 24 2pH 6.74 6.89 6.96 7.07 7.12 7.26 7.50 44 0Total phosphorous 0.012 0.026 0.016 0.030 0.041 0.043 0.149 15 0Specific conductance 68 80 83 96 104 122 135 44 0Sulfate (as SO42-) 4.74 5.94 6.59 7.43 7.72 8.11 8.83 44 0

Total dissolved nitrogen 0.37 0.55 0.592 0.68 0.755 0.87 1.27 41 1Total suspended solids 1 2 2 27 89 312 717 28 2Turbidity 1 2 3 24 56 129 296 24 0
Appendix 2 31

Table 2–2. Water-quality statistics of Calkins Creek at Milanville, PA (0142770105).[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower 

95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th 

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 9.10 11.15 11.35 15.61 18.70 22.50 26.32 30 0

Ammonium 0.00 0.00 NA 0.01 NA 0.02 0.04 28 23

Chloride 3.93 4.33 4.52 5.27 5.98 6.29 7.19 30 0

Dissolved organic carbon 1.63 1.88 1.90 2.25 2.72 3.29 4.00 30 0

Aluminum 0.009 0.014 NA 0.022 0.028 0.040 0.056 30 19

Calcium 5.49 6.06 6.46 7.39 8.10 8.79 10.05 30 0

Magnesium 0.84 0.93 0.95 1.11 1.26 1.39 1.60 30 0

Potassium 0.79 0.85 0.87 1.03 1.21 1.35 1.86 30 0

Silicon 0.92 1.13 1.14 1.57 1.68 1.93 1.99 30 0

Sodium 2.64 2.93 2.97 3.38 3.69 3.92 4.54 30 0

Nitrate (as NO3) 0.18 0.63 0.70 1.33 1.66 1.80 2.28 29 2

Particulate organic carbon 0 0 NA 1 1 2 8 9 5

pH 6.88 7.01 7.03 7.14 7.31 7.37 7.57 30 0

Total phosphorous 0.014 0.023 0.016 0.028 0.038 0.062 0.095 15 0

Specific conductance 52 59 60 68 76 84 91 30 0

Sulfate (as SO42-) 5.90 6.38 6.40 6.87 7.11 7.53 7.97 30 0

Total dissolved nitrogen 0.14 0.30 0.31 0.42 0.51 0.56 0.69 27 0

Total suspended solids 0 1 NA 1 2 3 45 13 1

Turbidity 1 1 NA 2 9 12 36 10 0
32 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–3. Water-Quality Statistics of Halfway Brook at Barryville, NY (01432180). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 2.54 3.57 3.84 5.04 7.16 8.33 18.68 30 0 Ammonium 0.01 0.02 NA 0.02 NA 0.03 0.04 30 22 Chloride 10.00 13.58 14.61 17.64 20.60 23.30 32.44 30 0 Dissolved organic carbon 1.64 2.13 2.21 2.74 2.99 3.27 4.33 30 0 Aluminum 0.015 0.022 NA 0.033 0.05 0.054 0.076 30 11 Calcium 3.02 3.35 3.45 3.98 4.42 4.95 7.45 30 0 Magnesium 0.78 0.86 0.88 1.00 1.09 1.24 1.86 30 0 Potassium 0.44 0.47 0.48 0.54 0.57 0.63 0.83 30 0 Silicon 1.29 1.43 1.51 1.64 1.87 2.01 2.14 30 0 Sodium 5.38 8.24 8.68 10.86 12.17 13.40 21.12 30 0 Nitrate (as NO3

) 0.12 0.17 0.19 0.31 0.47 0.55 0.76 30 4

Particulate organic carbon 1 1 NA 1 1 2 2 8 2

pH 6.22 6.43 6.59 6.75 6.96 6.99 7.22 30 0

Total phosphorous 0.010 0.014 NA 0.017 0.020 0.027 0.035 14 0

Specific conductance 53 72 75 92 102 110 166 30 0

Sulfate (as SO4

2-) 6.46 6.97 7.11 7.40 7.72 7.98 8.82 30 0

Total dissolved nitrogen 0.04 0.18 0.19 0.22 0.26 0.30 0.34 28 1

Total suspended solids 0 1 1 1 3 4 21 15 2

Turbidity 0 1 NA 2 7 7 13 10 0
Appendix 2 33

Table 2–4. Water-Quality Statistics of Lackawaxen River at Rowland, PA (01432110),.[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower 

95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th 

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 7.70 8.67 9.09 10.34 12.06 13.01 17.20 43 0

Ammonium 0.01 0.02 NA 0.03 0.03 0.04 0.06 43 22

Chloride 5.86 6.52 6.99 7.88 8.48 9.64 11.19 43 0

Dissolved organic carbon 2.37 2.50 2.58 2.72 3.07 3.37 4.26 43 0

Aluminum 0.010 0.015 NA 0.024 0.029 0.037 0.047 43 23

Boron 0.001 0.001 NA 0.003 NA 0.006 0.012 43 38

Calcium 4.91 5.33 5.57 6.23 6.40 7.06 8.45 43 0

Magnesium 0.73 0.82 0.85 0.90 0.94 1.01 1.19 43 0

Potassium 0.67 0.69 0.70 0.77 0.84 0.95 1.26 43 0

Silicon 0.56 0.89 0.93 1.10 1.15 1.31 1.65 43 0

Sodium 3.42 3.94 4.15 4.78 5.29 5.76 6.27 43 0

Nitrate (as NO3) 0.22 0.50 0.59 0.69 0.79 1.01 1.32 43 4

Particulate organic carbon 1 1 1 3 4 4 7 23 1

pH 6.79 6.88 6.93 7.06 7.11 7.18 7.26 43 0

Total phosphorous 0.013 0.020 0.019 0.024 0.026 0.032 0.071 15 0

Specific conductance 55 60 60 69 73 79 88 43 0

Sulfate (as SO42-) 5.92 6.62 6.75 7.29 7.70 8.11 8.63 43 0

Total dissolved nitrogen 0.21 0.28 0.32 0.35 0.37 0.41 0.54 41 0

Total suspended solids 1 2 2 6 11 28 53 27 1

Turbidity 1 2 2 6 14 16 32 22 0
34 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–5. Water-Quality Statistics of Mill Brook at mouth at Pond Eddy, NY (0143280005). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except for pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Cel- sius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 3.03 5.78 5.78 7.83 9.71 11.29 17.38 28 0 Chloride 11.73 15.94 16.00 18.69 20.90 22.75 25.36 25 0 Dissolved organic carbon 1.54 2.03 2.15 2.61 3.23 3.32 4.18 28 0 Aluminum 0.013 0.020 NA 0.031 0.047 0.064 0.075 28 12 Boron 0.003 0.005 NA 0.007 NA 0.010 0.015 28 23 Calcium 3.83 4.53 4.62 5.39 6.03 6.59 8.88 28 0 Magnesium 0.82 0.99 1.05 1.18 1.27 1.43 1.90 28 0 Potassium 0.42 0.44 0.45 0.50 0.55 0.58 0.65 28 0 Silicon 1.60 1.75 1.76 1.89 2.03 2.08 2.38 28 0 Sodium 7.61 8.95 9.02 9.95 10.88 12.13 12.44 28 0 Nitrate (as NO3

) 0.16 0.22 0.23 0.35 0.49 0.59 0.88 27 0

Particulate organic carbon 1 1 NA 1 2 2 2 8 2pH 6.38 6.74 6.79 6.93 7.01 7.09 7.28 28 0Total phosphorous 0.006 0.008 NA 0.011 0.013 0.013 0.016 11 0Specific conductance 70 86 87 94 101 108 132 28 0Sulfate (as SO42-) 6.19 6.67 6.75 7.07 7.29 7.35 7.79 27 0

Total dissolved nitrogen 0.11 0.16 0.17 0.22 0.25 0.26 0.34 26 0

Total suspended solids 0 1 NA 1 2 3 8 13 3

Turbidity 0 0 NA 1 2 2 4 8 0
Appendix 2 35

Table 2–6. Water-Quality Statistics of Mongaup River near Mongaup, NY (01433500).[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower 

95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th 

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 5.36 6.22 5.96 7.81 8.42 8.85 9.44 21 0

Ammonium 0.01 0.01 NA 0.02 0.03 0.04 0.06 21 13

Chloride 11.90 15.00 14.30 16.83 17.70 18.47 20.41 19 0

Dissolved organic carbon 2.63 2.75 2.74 2.97 3.19 3.77 4.80 21 0

Aluminum 0.016 0.022 NA 0.029 0.040 0.041 0.064 21 8

Calcium 4.32 4.59 4.57 4.99 5.51 5.59 5.76 21 0

Magnesium 0.86 0.94 0.93 1.02 1.10 1.13 1.17 21 0

Potassium 0.71 0.74 0.73 0.79 0.84 0.86 0.88 21 0

Silicon 0.75 0.88 0.88 1.14 1.46 1.66 1.77 21 0

Sodium 7.34 8.17 7.96 9.40 9.68 9.84 11.17 21 0

Nitrate (as NO3) 0.28 0.61 0.61 0.76 0.87 1.04 1.39 20 0

Particulate organic carbon 1 1 NA 1 1 1 2 11 2

pH 6.69 6.74 6.73 6.88 6.99 7.03 7.18 21 0

Total phosphorous 0.010 0.011 0.011 0.013 0.016 0.016 0.024 14 0

Specific conductance 75 82 81 87 92 93 102 21 0

Sulfate (as SO42-) 6.00 6.21 6.20 6.67 7.38 7.48 8.12 20 0

Total dissolved nitrogen 0.19 0.27 0.26 0.35 0.39 0.42 0.45 19 0

Total suspended solids 1 2 NA 2 2 3 4 15 0

Turbidity 1 1 NA 2 4 4 6 10 0
36 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–7. Water-Quality Statistics of Twin Lakes Creek near Shohola, PA (01432600). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 2.28 3.54 NA 6.23 8.87 8.89 10.74 13 0 Ammonium 5.50 6.58 NA 7.11 NA 7.96 8.85 13 0 Chloride 1.18 1.82 NA 2.65 7.95 3.13 4.02 13 0 Dissolved organic carbon 0.01 0.02 NA 0.03 3.03 0.04 0.09 13 5 Aluminum 0.014 0.020 NA 0.028 0.039 0.040 0.093 13 5 Calcium 2.29 2.75 NA 3.39 4.06 4.10 4.59 13 0 Magnesium 0.83 1.01 NA 1.22 1.43 1.46 1.61 13 0 Potassium 0.35 0.37 NA 0.40 0.41 0.41 0.54 13 0 Silicon 1.46 1.78 NA 2.02 2.24 2.26 2.70 13 0 Sodium 3.94 4.26 NA 4.59 4.76 4.78 5.05 13 0 Nitrate (as NO3

) 0.13 0.20 NA 0.40 0.56 0.59 0.84 13 2

Particulate organic carbon 1 1 NA 1 1 1 2 8 2

pH 6.36 6.52 NA 6.85 7.02 7.04 7.16 13 0

Total phosphorous 0.012 0.013 NA 0.015 NA 0.018 0.019 11 0

Specific conductance 44 49 NA 55 61 62 63 13 0

Sulfate (as SO42-) 5.75 6.45 NA 6.51 6.86 6.97 7.51 13 0

Total dissolved nitrogen 0.04 0.21 NA 0.25 0.27 0.28 0.32 12 1

Total suspended solids 1 1 NA 2 4 6 7 12 1

Turbidity 1 1 NA 1 2.41 2 3 7 0
Appendix 2 37

Table 2–8. Water-Quality Statistics of West Colang Creek at West Colang, PA (0142848005).[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower 

95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 2.95 3.55 3.62 4.38 5.61 6.55 8.65 30 0

Ammonium 9.67 10.72 NA 12.82 NA 14.11 15.11 30 0

Chloride 1.60 1.67 11.54 2.10 13.60 2.64 3.18 30 0

Dissolved organic carbon 0.01 0.01 1.70 0.02 2.49 0.03 0.07 30 19

Aluminum 0.008 0.012 NA 0.021 0.027 0.030 0.068 30 19

Boron 0.006 0.007 NA 0.008 NA 0.010 0.011 30 26

Calcium 2.93 3.25 3.32 3.63 3.73 3.84 4.20 30 0

Magnesium 1.13 1.24 1.30 1.37 1.44 1.48 1.61 30 0

Potassium 0.54 0.57 0.59 0.62 0.64 0.65 0.74 30 0

Silicon 1.26 1.50 1.53 1.73 1.84 1.98 2.31 30 0

Sodium 5.67 6.30 6.41 6.93 7.59 7.75 8.67 30 0

Nitrate (as NO3) 0.13 0.20 0.22 0.33 0.58 0.65 0.87 30 3

Particulate organic carbon 1 1 NA 1 1 2 4 9 2

pH 6.46 6.54 6.56 6.71 6.79 6.89 7.09 30 0

Total phosphorous 0.009 0.011 0.010 0.024 0.029 0.032 0.039 14 0

Specific conductance 60 66 68 71 76 78 85 30 0

Sulfate (as SO42-) 6.48 6.88 6.96 7.41 7.64 7.89 8.68 30 0

Total dissolved nitrogen 0.13 0.17 0.18 0.23 0.27 0.32 0.38 27 0

Total suspended solids 1 1 NA 3 3 4 9 14 3

Turbidity 0 1 NA 2 2 2 5 8 0
38 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–9. Water-Quality Statistics of East Branch Delaware River at Fishs Eddy, NY (01421000). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 5.19 6.62 7.62 8.57 9.39 11.01 13.57 68 0 Ammonium 0.01 0.01 NA 0.03 0.04 0.05 0.10 68 31 Chloride 3.16 4.15 5.13 6.00 6.65 8.20 9.11 65 0 Dissolved organic carbon 1.30 1.47 1.58 1.80 2.07 2.47 3.41 68 0 Aluminum 0.004 0.009 NA 0.022 0.030 0.061 0.121 68 38 Boron 0.001 0.002 NA 0.005 NA 0.011 0.037 67 48 Calcium 3.72 3.99 4.35 4.86 5.08 5.77 6.53 68 0 Magnesium 0.69 0.76 0.84 0.94 0.99 1.08 1.22 68 0 Potassium 0.43 0.45 0.46 0.51 0.59 0.61 0.70 68 0 Silicon 0.69 0.83 0.92 0.99 1.06 1.10 1.25 68 0 Sodium 2.01 2.68 3.10 3.51 4.03 4.66 5.42 68 0 Nitrate (as NO3

) 0.80 0.98 1.18 1.27 1.45 1.70 2.04 67 0

Particulate organic carbon 1 1 2 3 8 12 50 47 6

pH 6.51 6.71 6.80 6.87 6.94 7.04 7.15 68 0

Total phosphorous 0.002 0.006 0.005 0.009 0.024 0.157 1.627 21 1

Specific conductance 40 44 51 56 59 64 72 68 0

Sulfate (as SO42-) 4.75 5.44 5.66 5.83 5.92 6.13 6.40 68 0

Total dissolved nitrogen 0.22 0.30 0.36 0.39 0.43 0.48 0.59 65 1

Total suspended solids 2 5 9 36 108 376 1,682 52 1

Turbidity 1 3 7 21 57 199 1,928 45 0
Appendix 2 39

Table 2–10. Water-Quality Statistics of West Branch Delaware River at Hale Eddy, NY (01426500).[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower 

95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th 

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 7.43 10.79 11.72 12.74 13.10 14.38 15.51 65 0

Ammonium 0.01 0.02 NA 0.03 0.04 0.05 0.09 64 29

Chloride 7.68 8.65 9.78 10.68 11.13 12.16 13.45 63 0

Dissolved organic carbon 1.55 1.68 1.81 1.94 2.04 2.26 2.91 65 0

Aluminum 0.001 0.004 NA 0.010 NA 0.028 0.091 65 48

Boron 0.001 0.001 NA 0.003 NA 0.007 0.015 64 55

Calcium 4.62 5.54 5.89 6.19 6.35 6.61 6.79 65 0

Magnesium 1.24 1.38 1.46 1.51 1.56 1.61 1.73 65 0

Potassium 0.82 0.86 0.90 0.92 0.93 0.98 1.22 65 0

Silicon 1.00 1.24 1.32 1.41 1.49 1.56 1.65 65 0

Sodium 5.01 5.43 6.05 6.39 6.61 6.97 7.45 65 0

Nitrate (as NO3) 1.36 1.62 1.82 2.04 2.16 2.51 2.83 64 0

Particulate organic carbon 1 2 2 4 6 8 13 43 1

pH 6.74 6.83 6.88 6.96 7.03 7.11 7.18 65 0

Total phosphorous 0.007 0.008 0.007 0.010 0.019 0.027 0.058 16 0

Specific conductance 68 75 77 79 81 87 94 65 0

Sulfate (as SO42-) 6.07 6.31 6.64 6.95 7.08 7.49 8.24 65 0

Total dissolved nitrogen 0.44 0.49 0.52 0.58 0.59 0.67 0.80 62 0

Total suspended solids 2 7 9 27 68 114 316 49 0

Turbidity 2 4 5.29 13 25.2 58 121 42 0
40 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–11. Water-Quality Statistics of Delaware River at Callicoon, NY (01427510). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 6.42 7.89 8.38 10.51 11.44 12.63 15.15 61 0 Ammonium 0.01 0.01 NA 0.02 0.04 0.05 0.10 61 33 Chloride 4.21 5.86 6.37 7.87 8.40 9.26 10.01 59 0 Dissolved organic carbon 1.44 1.63 1.79 1.92 2.09 2.48 3.79 61 0 Aluminum 0.006 0.011 NA 0.020 NA 0.037 0.063 61 38 Boron 0.000 0.001 NA 0.002 NA 0.006 0.017 61 52 Calcium 4.07 4.52 4.93 5.26 5.66 6.02 6.69 61 0 Magnesium 0.80 0.88 0.97 1.08 1.16 1.25 1.42 61 0 Potassium 0.58 0.62 0.65 0.69 0.75 0.83 0.93 61 0 Silicon 0.62 0.74 0.92 1.00 1.12 1.19 1.33 61 1 Sodium 2.61 3.62 4.12 4.53 4.79 5.48 5.74 61 0 Nitrate (as NO3

) 0.80 1.06 1.13 1.28 1.46 1.64 2.27 60 0

Particulate organic carbon 1 2 3 6 12 14 21 40 3

pH 6.66 6.84 6.91 6.97 7.01 7.09 7.19 61 0

Total phosphorous 0.004 0.006 0.005 0.007 0.011 0.059 0.172 19 0

Specific conductance 47 55 58 63 67 73 81 61 0

Sulfate (as SO42-) 5.24 5.70 5.89 6.10 6.34 6.60 6.87 61 0

Total dissolved nitrogen 0.25 0.36 0.40 0.44 0.48 0.54 0.67 58 1

Total suspended solids 1 3 15 88 177 268 533 45 1

Turbidity 1 4 14 41 75 120 268 37 0
Appendix 2 41

Table 2–12. Water-Quality Statistics of Delaware River above Lackawaxen River near Barryville, NY (01428500).[Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available]

Constituent or property 10th percentile 25th percentile

Lower

 95-percent 

confidence 

limit

Median

Upper 

95-percent 

confidence 

limit

75th 

percentile

90th 

percentile

Number 

of 

samples

Number 

of 

censored 

samples

Acid neutralizing capacity 6.42 8.54 9.88 10.91 11.51 13.67 15.59 65 0

Ammonium 0.01 0.02 NA 0.03 0.03 0.04 0.08 65 33

Chloride 5.92 6.88 8.05 8.90 9.61 10.23 11.27 64 0

Dissolved organic carbon 1.56 1.70 1.85 2.12 2.24 2.82 4.50 64 0

Aluminum 0.003 0.007 NA 0.015 NA 0.036 0.059 65 44

Boron 0.001 0.001 NA 0.003 NA 0.007 0.012 65 56

Calcium 4.13 4.96 5.16 5.58 5.85 6.41 6.80 65 0

Magnesium 0.84 1.02 1.11 1.17 1.20 1.34 1.49 65 0

Potassium 0.63 0.68 0.70 0.74 0.79 0.83 0.96 65 0

Silicon 0.53 0.62 0.86 1.02 1.09 1.23 1.36 65 0

Sodium 3.30 4.15 4.69 5.25 5.41 5.82 6.19 65 0

Nitrate (as NO3) 0.79 1.01 1.09 1.21 1.41 1.60 1.84 65 0

Particulate organic carbon 1 2 3 3 4 5 11 44 3

pH 6.73 6.86 6.92 7.01 7.06 7.14 7.26 65 0

Total phosphorous 0.005 0.006 0.006 0.010 0.025 0.029 0.154 18 0

Specific conductance 52.04 62.60 64 67.30 74 77.80 82.86 65 0

Sulfate (as SO42-) 5.28 5.89 6.06 6.35 6.49 6.87 7.26 65 0

Total dissolved nitrogen 0.27 0.36 0.39 0.43 0.45 0.53 0.60 63 0

Total suspended solids 1 3 11 27 46 57 238 49 1

Turbidity 1 5 7 12 27 43 121 41 0
42 Water Quality of Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania Table 2–13. Water-Quality Statistics of Delaware River at Port Jervis, NY (01434000). [Values are in milligrams per liter (acid neutralizing capacity in milligrams calcium carbonate per liter) except pH (standard units), specific conductance (microsiemens per centimeter at 25 degrees Celsius), and turbidity (nephelometric turbidity units). Censored samples are those with results below the detection limit. NA, not available] Constituent or property 10th percentile 25th percentile Lower 95-percent confidence limit Median Upper 95-percent confidence limit 75th percentile 90th percentile Number of samples Number of censored samples Acid neutralizing capacity 6.41 8.41 9.70 10.51 11.04 13.41 14.97 68 0 Ammonium 0.00 0.01 NA 0.02 0.04 0.05 0.10 68 34 Chloride 5.60 7.36 8.31 9.54 10.01 10.91 11.66 66 0 Dissolved organic carbon 1.76 1.98 2.14 2.48 2.68 3.29 4.43 68 0 Aluminum 0.008 0.013 NA 0.023 0.032 0.041 0.059 68 39 Boron 0.001 0.002 NA 0.003 NA 0.007 0.012 68 60 Calcium 4.13 4.97 5.30 5.66 6.00 6.48 6.78 68 0 Magnesium 0.84 1.00 1.05 1.12 1.19 1.26 1.42 68 0 Potassium 0.64 0.68 0.71 0.76 0.78 0.85 1.00 68 0 Silicon 0.47 0.60 0.77 1.06 1.11 1.26 1.43 68 0 Sodium 3.45 4.42 4.92 5.52 5.97 6.34 6.66 68 0 Nitrate (as NO3

) 0.56 0.83 0.91 0.99 1.11 1.25 1.61 68 0

Particulate organic carbon 1 1 1 3 4 6 9 50 5pH 6.73 6.86 6.93 7.00 7.07 7.14 7.23 68 0Total phosphorous 0.008 0.009 0.009 0.014 0.017 0.042 0.449 19 0Specific conductance 51 61 66 71 76 80 85 68 0Sulfate (as SO42-) 5.54 6.18 6.40 6.56 6.76 7.15 7.61 68 0

Total dissolved nitrogen 0.18 0.33 0.36 0.39 0.41 0.47 0.56 67 1Total suspended solids 1 3 9 19 34 49 164 52 1Turbidity 2 3 4 11 19 29 68 44 0
Appendix 3 43

Appendix 3. Yields of Selected Constituents for intensive Sites in the Upper Delaware River Basin, Water Years 2006 and 2007. [Values are in kilograms per hectare per year. NA, not available. The water year is defined as the period from October 1 to September 30, and is designated by the year in which it ends.]

Constituent or property

Callicoon Creek East Branch Delaware 

River at Fishs Eddy, NY

West Branch Delaware 

River at Hale Eddy, NY

Delaware River 

at Callicoon, NY

Delaware River 

at Barryville, NY

Delaware River 

at Port Jervis, NY

Water 

year 

2006

Water 

year 

2007

Water 

year 

2006

Water 

year 

2007

Water 

year 

2006

Water 

year 

2007

Water 

year 

2006

Water 

year 

2007

Water 

year 

2006

Water 

year 

2007

Water 

year 

2006

Water 

year 

2007

Ammonium 0.40 0.70 0.94 0.24 0.37 0.19 0.18 0.29 0.20 0.22 0.33 0.44

Chloride 50 38 14 13 26 25 24 17 25 19 24 20

Dissolved organic carbon 40 24 17 11 14 15 16 13 18 16 24 17

Aluminum 0.34 0.11 0.32 0.06 0.13 0.07 0.11 0.07 0.45 0.07 0.14 0.08

Calcium 84 58 35 33 43 47 46 37 48 39 42 37

Magnesium 15 10 6.9 6.4 11 12 9.5 7.8 9.8 8.2 8.2 7.4

Potassium 17 12 4.4 3.4 6.6 7.2 5.7 4.78 6.2 5.2 6.3 5.2

Silicon 6.4 4.4 3.7 3.0 3.8 5.1 3.4 3.4 3.4 3.4 3.8 3.2

Sodium 82 59 25 23 45 45 40 29 42 32 39 34

Nitrate (as NO3) 29 23 7.7 12 13 19 8.4 12 8.7 12 8.1 8.5

Total phosphorous NA NA NA NA NA NA NA NA NA NA NA NA

Sulfate (as SO42-) 98 58 44 38 54 52 57 43 58 45 56 43

Total dissolved nitrogen 7.0 7.0 2.1 2.9 3.2 4.2 2.4 3.2 2.5 2.9 2.0 2.7

Total monomeric aluminum NA NA 0.36 0.09 0.07 0.06 0.06 0.11 0.06 0.07 0.24 0.04

Total suspended solids NA 1,200 NA 690 NA 230 NA 1,050 NA 260 NA 190
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Siemion and Murdoch—Water Quality of the Upper Delaware Scenic and Recreational River and Tributary Streams, New York and Pennsylvania—Scientific Investigations Report 2010–5009