U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2011–5151

Prepared in cooperation with the National Park Service

Characterization of Major-Ion Chemistry and 

Nutrients in Headwater Streams Along the 

Appalachian National Scenic Trail and Within 

Adjacent Watersheds, Maine to Georgia
Front cover. Bumpus Brook above Stairs Falls on the Howker Ridge Trail of Mount Madison in Coos County, New Hampshire. 

(Photograph published with permission from Nancy Gaudreau) 

Back cover. Appalachian National Scenic Trail in the Pisgah National Forest, east of Roan Highlands, North Carolina. 

(Photograph published with permission from Nancy Gaudreau)
Characterization of Major-Ion Chemistry 

and Nutrients in Headwater Streams 

Along the Appalachian National Scenic 

Trail and Within Adjacent Watersheds, 

Maine to Georgia

By Denise M. Argue, Jason P. Pope, and Fred Dieffenbach

Prepared in cooperation with the National Park Service

Scientific Investigations Report 2011–5151

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: 2012

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

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

U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Argue, D.M., Pope, J.P., and Dieffenbach, Fred, 2012, Characterization of major-ion chemistry and nutrients in 

headwater streams along the Appalachian National Scenic Trail and within adjacent watersheds, Maine to Georgia: 

U.S. Geological Survey Scientific Investigations Report 2011–5151, 63 p., plus CD–ROM. (Also available at 

http://pubs.usgs.gov/sir/2011/5151.)
iii

Acknowledgments

The authors thank Dean Tucker, National Park Service (NPS) for extracting the water-quality 

data and sampling sampling-site information from the U.S. Geological Survey’s National Water 

Information System database and from the U.S. Environmental Protection Agency’s STOrage and 

RETrieval databases (including the Legacy STORET database) for the area within a 20-mile buffer 

about the Appalachian Trail. A wide variety of supporting geospatial data were supplied by 

Casey Reese (NPS) and Matt Robinson (NPS). The authors also thank the individuals who were 

the stewards of the multiple additional datasets obtained for this project for providing these 

data to the authors and assisting the authors with their proper use. The authors recognize that 

data provided by the Coweeta Long Term Ecological Research (LTER) program were collected in 

the course of research supported by the National Science Foundation (NSF) award DEB-0823293 

from the Long Term Ecological Research Program to the Coweeta LTER Program at the University 

of Georgia and that opinions, findings, conclusion, or recommendations expressed in this report 

do not necessarily reflect the views of the National Science Foundation or the University of 

Georgia. The authors recognize that the long-term streamwater chemistry data from Hubbard 

Brook LTER were provided by Gene Likens through funding supported from the NSF, including 

LTER and Long Term Research in Environmental Biology programs and the Andrew W. Mellon 

Foundation.
THIS PAGE INTENTIONALLY LEFT BLANK
v

Contents

Acknowledgments........................................................................................................................................iii

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

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

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

Description of the Study Area ............................................................................................................5

Delineation of Study Area ..........................................................................................................5

Geology..........................................................................................................................................5

Topography ...................................................................................................................................7

Precipitation and Temperature..................................................................................................7

Hydrology ......................................................................................................................................8

Physiographic and Ecological Divisions..................................................................................9

Previous Investigations......................................................................................................................15

Sources of Water-Quality Data..................................................................................................................16

Acid Rain Monitoring Program.........................................................................................................17

Coweeta LTER Program .....................................................................................................................17

Hubbard Brook LTER Program..........................................................................................................17

Delaware Water Gap National Recreation Area...........................................................................17

Great Smoky Mountains National Park...........................................................................................17

Virginia Trout Stream Sensitivity Study (VTSSS)...........................................................................19

White Mountain National Forest......................................................................................................19

Environmental Monitoring and Assessment Program (EMAP)...................................................19

Temporally Integrated Monitoring of Ecosystems and Long Term Monitoring Program 

(TIME/LTM).............................................................................................................................19

National Stream Survey Program ....................................................................................................19

Wadeable Stream Assessment Program........................................................................................19

Methods of Analysis....................................................................................................................................20

Quality Assurance and Compilation of Water-Quality Data ........................................................20

Quality Assurance......................................................................................................................20

Data Compilation........................................................................................................................20

Ancillary Data Sources......................................................................................................................21

Hydrologic Attributes ................................................................................................................21

Environmental Attributes..........................................................................................................25

Site Selection.......................................................................................................................................25

Criteria for Selection of Nonadjacent Sampling Sites.........................................................25

Selected Sites and Data Aggregation....................................................................................26

Statistical Methods.............................................................................................................................36

Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing 

Capacity, and Nutrients.................................................................................................................37

Field Properties ...................................................................................................................................37

Major Ions............................................................................................................................................39

Acid Neutralizing Capacity................................................................................................................46

Nutrients...............................................................................................................................................47
vi

Figures

1. Map showing location of the Appalachian National Scenic Trail and study area............3

2. Photograph showing the Appalachian National Scenic Trail north of Roanoke, 

Virginia............................................................................................................................................4

3. Map showing the percentage of forested land cover in the study area.............................6

4. Photograph showing the Appalachian National Scenic Trail passing through an open 

field on Cross Mountain near Shady Valley, Tennessee........................................................7

5. Photograph showing the Appalachian National Scenic Trail on Franconia Ridge, 

near Franconia, New Hampshire ...............................................................................................8

6. Photograph showing a first-order stream, typical of the high-elevation streams 

that are crossed by the Appalachian National Scenic Trail..................................................9

7. Map showing U.S. Forest Service ecological sections (ecosections) that intersect 

the study area..............................................................................................................................13

8. Photograph showing the Appalachian National Scenic Trail passing over Little 

Hump in North Carolina through the region known as the “balds” ...................................14

9. Map showing hydrologic subregions that intersected and were used as geographic 

subdivisions of the study area..................................................................................................23

10. Schematic diagram showing examples of the nested relation of National 

Hydrography Dataset Plus catchments with larger delineated hydrographic units 

such as subwatersheds, and drainage areas defined for a set of nested catchments .24

11. Index map showing areas covered by figures 12 and 13.....................................................27

12. Maps showing first- and second-order catchments from the National Hydrography 

Dataset Plus that are adjacent to the Appalachian National Scenic Trail and were 

used to characterize physical attributes of the trail environment from A, Maine to 

Vermont, B, Massachusetts to Maryland, C, Maryland to Virginia, and D, Virginia 

to Georgia.....................................................................................................................................28

13. Maps showing the spatial distribution of and the number of sampling sites in 

National Hydrography Dataset Plus catchments used in the level 1 inventory of firstand second-order streams along the Appalachian National Scenic Trail, A, Maine to 

Vermont, B, Massachusetts to Maryland, C, Maryland to Virginia, and D, Virginia to 

Georgia .........................................................................................................................................32

14. Boxplots showing comparisons of concentrations of A, pH, B, specific conductance, 

C, acid neutralizing capacity, D, calcium, E, magnesium, F, sodium, G, potassium, 

H, sulfate, I, chloride, J, nitrate, K, ammonia, L, total nitrogen, and M, total phosphorus, 

by U.S. Forest Service ecological sections (ecosections), from catchments that 

contain selected first- and second-order streams along the Appalachian National 

Scenic Trail ..................................................................................................................................44

Effects of Environmental Attributes on Water Quality...........................................................................48

Elevation...............................................................................................................................................49

Geology.................................................................................................................................................49

Land Cover...........................................................................................................................................51

Atmospheric Deposition ....................................................................................................................51

Implications of Using Available Data and Considerations for Future Monitoring.............................55

Summary........................................................................................................................................................56

Selected References...................................................................................................................................58

Appendix 1. Ancillary and Water-Quality Variable Definitions and Catchment Data 

(on CD–ROM)...................................................................................................................................63
vii

15. Map showing major geologic units within the study area ..................................................50

16. Boxplots showing comparison of concentrations, by major geologic groups, of 

A, pH, B, specific conductance, and C, acid neutralizing capacity from catchments 

that contained selected first- and second-order streams along the Appalachian 

National Scenic Trail..................................................................................................................52

17. Maps of 1994 annual wet-deposition estimates for A, sulfate and B, nitrate for the 

eastern United States, including the study area...................................................................53

18. Boxplots showing wet-deposition estimates from 1994 of A, sulfate and B, nitrate by 

U.S. Forest Service ecological sections (ecosections) for all first and second order 

catchments in the study area ...................................................................................................54

Tables

1. Description of landscapes, geology, and primary land cover for physiographic 

provinces and U.S. Forest Service ecological sections.......................................................10

2. Appalachian National Scenic Trail level 1 inventory of data sources used, project 

acronym, number of sampling sites, number of records, and the period of record for 

the water-quality data initially compiled.................................................................................18

3. Types and sources of ancillary data used in this study .......................................................22

4. Threshold values, by subregion, of selected physical attributes used to screen 

nonadjacent sampling sites for inclusion in the water-quality summary of selected 

sampling sites along the Appalachian National Scenic Trail..............................................36

5. Summary statistics of selected physical attributes, by U.S. Forest Service ecological 

sections (ecosections), from catchments that contain selected sampling sites along 

the Appalachian National Scenic Trail ...................................................................................38

6. Summary statistics of concentrations of selected water-quality constituents from 

catchments that contain selected sampling sites along the Appalachian National 

Scenic Trail ..................................................................................................................................39

7. Water temperature and dissolved oxygen concentrations by U.S. Forest Service 

ecological sections (ecosections) and by season from selected sampling sites along 

the Appalachian National Scenic Trail ...................................................................................40

8. Summary statistics of selected water-quality constituents by U.S. Forest Service 

ecological sections (ecosections) from catchments that contain selected sampling 

sites in headwater streams along the Appalachian National Scenic Trail.......................41

9. Comparison among U.S. Forest Service ecological sections (ecosections) of the 

percentages of catchments with acid neutralizing capacity classified as acidic, 

sensitive, or insensitive .............................................................................................................46

10. Comparison of median catchment concentrations of nutrients and the percentages 

of median concentrations greater than estimated national background concentrations 

from selected sampling sites along the Appalachian National Scenic Trail....................47

11. Comparison, by nutrient ecoregion, of median catchment concentrations of total 

nitrogen and total phosphorus and the percentages of median catchment concentrations greater than U.S. Environmental Protection Agency’s nutrient criteria from 

selected sampling sites along the Appalachian National Scenic Trail .............................48

12. Rho values from Spearman correlations of the elevations of catchments and the 

percentages of developed and agricultural land cover with concentrations of 

selected water-quality constituents in catchments that contained selected sampling 

sites along the Appalachian National Scenic Trail...............................................................49

13. Rho values from Spearman correlations of elevation with selected environmental 

attributes of catchments that contain selected sampling sites along the Appalachian 

National Scenic Trail..................................................................................................................49
viii

Conversion Factors, Abbreviations, and Acronyms

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)

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

 °F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

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

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), 

micrograms per liter (μg/L), micromoles per liter (μmol/L), and microequivalents per liter (μeq/L).

Concentrations of chemical constituents in wet-atmospheric deposition are given in kilograms 

per hectare (kg/ha).

Acronyms

ANC acid neutralizing capacity

ATC Appalachian Trail Conservancy

CAAA Clean Air Act Amendments of 1990

EMAP Environmental Monitoring and Assessment Program

LTER Long Term Ecological Research

LTM Long Term Monitoring

NADP National Atmospheric Deposition Program

NHD National Hydrography Dataset

NPS National Park Service

NSF National Science Foundation

NWIS National Water Information System

STORET STORage and RETrieval database operated by the U.S. Environmental 

 Protection Agency

TIME Temporally Integrated Monitoring of Ecosystems

USEPA U.S. Environmental Protection Agency

USFS U.S. Forest Service

USGS U.S. Geological Survey

VTSSS Virginia Trout Stream Sensitivity Study
Abstract

An inventory of water-quality data on field parameters, 

major ions, and nutrients provided a summary of water 

quality in headwater (first- and second-order) streams within 

watersheds along the Appalachian National Scenic Trail 

(Appalachian Trail). Data from 1,817 sampling sites in 

831 catchments were used for the water-quality summary. 

Catchment delineations from NHDPlus were used as the 

fundamental geographic units for this project. Criteria used 

to evaluate sampling sites for inclusion were based on 

selected physical attributes of the catchments adjacent to the 

Appalachian Trail, including stream elevation, percentage of 

developed land cover, and percentage of agricultural 

land cover. 

The headwater streams of the Appalachian Trail are 

generally dilute waters, with low pH, low acid neutralizing 

capacity (ANC), and low concentrations of nutrients. The 

median pH value was slightly acidic at 6.7; the median specific conductance value was 23.6 microsiemens per centimeter, 

and the median ANC value was 98.7 milliequivalents per liter 

(μeq/L). Median concentrations of cations (calcium, magnesium, sodium, and potassium) were each less than 1.5 milligrams per liter (mg/L), and median concentrations of anions 

(bicarbonate, chloride, fluoride, sulfate, and nitrate) were less 

than 10 mg/L. 

Differences in water-quality constituent levels along the 

Appalachian Trail may be related to elevation, atmospheric 

deposition, geology, and land cover. Spatial variations were 

summarized by ecological sections (ecosections) developed 

by the U.S. Forest Service. Specific conductance, pH, 

ANC, and concentrations of major ions (calcium, chloride, 

magnesium, sodium, and sulfate) were all negatively 

correlated with elevation. The highest elevation ecosections 

(White Mountains, Blue Ridge Mountains, and Allegheny 

Mountains) had the lowest pH, ANC, and concentrations of 

major ions. The lowest elevation ecosections (Lower New 

England and Hudson Valley) generally had the highest pH, 

ANC, and concentrations of major ions. The geology in 

discrete portions of these two ecosections was classified as 

containing carbonate minerals which has likely influenced the 

chemical character of the streamwater. Specific conductance, 

pH, ANC, and concentrations of major ions (calcium, chloride, 

magnesium, sodium, and sulfate) were all positively correlated 

with percentages of developed and agricultural land uses at 

the lower elevations of the central region of the Appalachian 

Trail (including the Green–Taconic–Berkshire Mountains, 

Lower New England, Hudson Valley, and Northern Ridge and 

Valley ecosections). The distinctly different chemical character 

of the streams in the central sections of the Appalachian 

Trail is likely related to the lower elevations, the presence 

of carbonate minerals in the geology, higher percentages of 

developed and agricultural land uses, and possibly the higher 

inputs of sulfate and nitrate from atmospheric deposition. 

Acid deposition of sulfate and nitrate are important 

influences on the acid-base chemistry of the surface waters 

of the Appalachian Trail. Atmospheric deposition estimates 

are consistently high (more than 18 kilograms per hectare 

(kg/ha) for sulfate, and more than 16 kg/ha for nitrate) at 

both the highest and lowest elevations. However, the lowest 

elevation (Green–Taconic–Berkshire Mountains, Lower 

New England, Hudson Valley, Northern Glaciated Allegheny 

Plateau, and Northern Ridge and Valley ecosections) 

included the largest spatial area of sustained high estimates 

of atmospheric deposition. 

Calcium-bicarbonate was the most frequently calculated 

water type in the Lower New England and Hudson Valley 

ecosections. In the northern and southern sections of the 

Appalachian Trail mix-cation water types were most prevalent 

and sulfate was the predominate anion. The predominance 

of the sulfate anion in the surface waters of the northern and 

southern ecosections likely reflects the influence of sulfate 

deposition. Although the central portion of the Appalachian 

Trail has the largest spatial area of high atmospheric acid 

Characterization of Major-Ion Chemistry and Nutrients 

in Headwater Streams Along the Appalachian National 

Scenic Trail and Within Adjacent Watersheds, 

Maine to Georgia

By Denise M. Argue1, Jason P. Pope2, and Fred Dieffenbach3

1

 U.S. Geological Survey.

2

 U.S. Geological Survey.

3

 National Park Service.
2 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

deposition, the lower ionic strength waters in the northern and 

southern ecosections of the Appalachian Trail may have been 

more adversely affected by acid deposition. 

The low ionic strength of the streams in the White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 

ecosections makes parts of these regions susceptible to 

seasonal or event-driven episodic acidification, which can be 

detrimental to health of aquatic and terrestrial ecosystems. 

Median catchment ANC values were classified into three 

groups—acidic, sensitive, and insensitive. The White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 

ecosections included the highest frequency of catchments 

classified as acidic or sensitive. More than 56 percent of 

the catchments from the White Mountains ecosection were 

classified as sensitive to acidic inputs. In the Blue Ridge 

ecosection, 1.6 percent of the catchments were classified as 

acidic, and 38.2 percent of the catchments were classified 

as sensitive to acidic inputs. In the Allegheny Mountains 

ecosection, 17.6 percent of the catchments were classified as 

acidic, and 29.4 percent of the catchments were classified as 

sensitive to acidic inputs.

Median concentrations of nitrogen species were less 

than 0.4 mg/L, and median concentrations of total phosphorus 

were less than 0.02 mg/L along the Appalachian Trail. A 

comparison of median catchment concentrations of nutrients 

to estimated national background concentrations demonstrated 

that concentrations along the Appalachian Trail are generally 

lower. A comparison of median concentrations of total 

nitrogen and total phosphorus to the U.S. Environmental 

Protection Agency’s (USEPA) nutrient criteria for the Eastern 

U.S. ecoregions showed that the concentrations of total 

nitrogen in the northern section of the Appalachian Trail were 

generally higher than the USEPA criterion. Similarly, median 

concentrations of total phosphorus in the southern regions of 

the Appalachian Trail were approximately twice as high as 

USEPA criteria. Sections of the Appalachian Trail are adjacent 

to modest amounts of agricultural and developed land areas. 

These nonforested land areas may be contributing to the 

percentage of catchments in which concentrations of total 

nitrogen and total phosphorus are higher than USEPA nutrient 

ecoregion criteria. 

Introduction

The level 1 inventory is a process used by the Water 

Resources Division of the National Park Service (NPS), to 

provide descriptive water-quality information for key water 

resources at NPS units throughout the United States. The 

Appalachian National Scenic Trail (Appalachian Trail) is a 

unit of the National Park System that extends along almost 

the entire Appalachian Mountain range in the Eastern United 

States (fig. 1). The Appalachian Trail passes from Maine to 

Georgia through 14 states, 6 national parks, 8 national forests, 

1 national wildlife refuge, and a variety of lands owned by 

federal, state, local, and nonprofit organizations (National Park 

Service, 2008). The Appalachian Trail is administered through 

a cooperative management system in which responsibilities 

are shared among the NPS, the U.S. Forest Service (USFS), 

the nonprofit Appalachian Trail Conservancy (ATC), and other 

organizations. More than 99 percent of the Appalachian Trail 

lies on protected land (National Park Service, 2008), and the 

trail traverses a wide variety of landscapes characteristic of the 

Appalachian Mountains.

The Appalachian Trail was originally conceived by 

Benton MacKaye, an early 20th Century conservationist, 

as a footpath (fig. 2) that linked a series of small isolated 

communities (MacKaye, 1921). While some of MacKaye’s 

original visions did not materialize, the trail itself did come 

together as a footpath that provides hikers the ability to 

traverse a largely intact wilderness located along the crest 

of the Appalachian Mountains. In recent years, as natural 

systems in the United States have been increasingly affected 

by human activities, including urbanization, pollution, 

habitat fragmentation, and invasive species, there has been 

an increased awareness and appreciation of the Appalachian 

Trail for its value as an intact corridor of protected natural 

lands and as a study area for research on the effects of human 

disturbance and variations in climate over time on natural 

systems (Shriver and others, 2005). 

The quality of water resources along the Appalachian 

Trail were identified by the NPS as a critical measure of 

the environmental health of the Appalachian Trail (Shriver, 

2005). A fundamental understanding of the natural-resource 

conditions along the Appalachian Trail is essential for the 

NPS to manage Appalachian Trail water resources in a way 

that is consistent with its mission. Water resources along the 

Appalachian Trail include streams, rivers, lakes, ponds, seeps, 

springs, wetlands, and wells. The form, structure, and occurrence of these water resources vary considerably, and their 

characteristics and occurrence may depend on the geology, climate, and the terrestrial ecological systems in particular areas. 

The water resources along the Appalachian Trail serve many 

uses, providing a source of drinking water for hikers, visitors, and wildlife; providing recreational, scenic and aesthetic 

value; habitat for plants and animals; and a source of water for 

downstream uses, such as public water supplies, fisheries, and 

hydropower generation.

An assessment of the quality of water resources along 

the Appalachian Trail has not been previously undertaken, 

although a variety of studies have been performed within 

specific regions and individual park units through which the 

Appalachian Trail passes. The current review conducted by the 

U.S. Geological Survey (USGS), in cooperation with the NPS, 

comprises a level 1 inventory of available water-quality data 

(1923–2009) along the Appalachian Trail. The NPS requested 

the USGS to perform a level 1 water-quality inventory of the 

Appalachian Trail to enable NPS to develop baseline waterquality information for key water resources that are defined as 

those waters that are essential to the central cultural, historical, or natural-resource-management themes of the park or 
Introduction 3

Figure 1. Location of the Appalachian National Scenic Trail and study area.

80° 75° 70°

45°

40°

35°

EXPLANATION

Appalachian National Scenic Trail

Study-area boundary

State boundary

VIRGINIA

NORTH CAROLINA

GEORGIA

TENNESSEE

WEST VIRGINIA

PENNSYLVANIA

NEW YORK

MAINE

NEW HAMPSHIRE

DELAWARE

NEW JERSEY

MASSACHUSETTS

CONNECTICUT

VERMONT

MARYLAND

0 100 200 MILES

0 150 300 KILOMETERS

Physical-map background from National Park Service

Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

Atlantic Ocean

Saint Lawrence River

Lake Ontario

Lake Erie

Lake 

Huron
4 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

that provide habitats for threatened or endangered plants and 

animals. The focus of this report is on headwater streams 

that represent one common, or ‘characteristic’ water resource 

that is key along the Appalachian Trail. This information will 

enhance the ability of NPS to manage park resources, could 

have direct relevance for future resource-monitoring activities, 

and may serve as a foundation from which changes in water 

quality could be assessed over time.

Purpose and Scope

This report summarizes the objectives, methods, and 

results of analyses of water-quality data compiled by the 

USGS for headwater streams (classified as first- and secondorder streams in the Strahler stream-order system) along and 

near the Appalachian Trail from Maine to Georgia. Specific 

objectives of this project include (1) compiling waterquality data collected along or near the Appalachian Trail; 

(2) determining the spatial coverage of water-quality data; 

(3) developing a method by which data could be screened to 

determine suitability for inclusion in water-quality summaries; (4) providing summary statistics of the concentrations 

of selected constituents typically used to describe basic water 

chemistry; (5) describing natural and anthropogenic factors 

that may explain the observed variability in water quality; and 

(6) evaluating how data can help guide future water-qualitymonitoring considerations. The parameters and constituents 

selected for analysis in this report include pH, specific conductance, dissolved oxygen, water temperature, acid neutralizing 

capacity (ANC), bicarbonate, calcium, chloride, fluoride, magnesium, potassium, silica, sodium, sulfate, ammonia, nitrate, 

total nitrogen, and total phosphorus. The focus is on basic 

chemical quality of headwater streams and the report does not 

include data on microbiological characteristics, trace elements, 

and other constituents that are commonly related to drinking 

water quality. 

Figure 2. The Appalachian National Scenic Trail (AT) north of Roanoke, Virginia. Symbol on the sign is an emblem for AT. (Photograph 

courtesy of Joseph Ayotte, U.S. Geological Survey)
Introduction 5

In an attempt to compile the most extensive inventory of 

water-quality data that characterize headwater streams along 

and nearby the Appalachian Trail, a method for incorporating 

sampling sites not adjacent to the Appalachian Trail (hereafter 

referred to as nonadjacent) was developed. The developed 

methodology for selecting nonadjacent sampling sites helped 

to ensure that the environmental setting of the selected nonadjacent sampling sites was representative of the Appalachian 

Trail environment and therefore appropriate for inclusion in 

this water-quality characterization. In this report, the term 

‘Appalachian Trail environment’ (not spatially defined) is used 

to refer to the general characteristics of the landscape features 

and surrounding area and resources in the immediate vicinity 

of the Appalachian Trail. 

Description of the Study Area

The Appalachian Trail is an approximately 2,175-mi-long 

footpath that follows the crest of the Appalachian Mountain 

range in the eastern United States. From its northern end in 

central Maine to its southern end in northern Georgia, the 

Appalachian Trail passes through 14 states, including New 

Hampshire, Vermont, Massachusetts, Connecticut, New York, 

New Jersey, Pennsylvania, Maryland, West Virginia, Virginia, 

North Carolina, and Tennessee (Shriver and others, 2005). The 

Appalachian Trail passes through a wide variety of landscapes 

representative of the Appalachian Mountains, including 

topographic classes such as high mountain ridges and peaks, 

rolling foothills, plateaus, and river valleys. 

Land along the Appalachian Trail is most commonly 

forested (fig. 3), with occasional open grassy (fig. 4) and 

rocky areas (fig. 5), and intermittent agricultural and 

developed areas (Dieffenbach, 2011). Farmland used for 

both row crops and pasture is also adjacent to many parts 

of the Appalachian Trail, but agricultural land is much 

more common in the mid-Atlantic than in other areas. The 

Appalachian Trail traverses land that is typically sparsely 

populated and relatively undeveloped, but it also passes near 

some large population centers, particularly in New York 

and Virginia. The Appalachian Trail actually passes through 

thirteen cities and towns defined as Urbanized Areas or Urban 

Clusters by the U.S. Census, including the New York–Newark 

Urbanized Area in New York and New Jersey, the Allentown–

Bethlehem Urbanized Area in Pennsylvania, and the Roanoke 

Urbanized Area in Virginia (U.S. Census, 2003). Overall, the 

Appalachian Trail constitutes a protected corridor of relatively 

undeveloped land where important natural ecosystems of the 

Appalachian highlands are preserved.

Land along the Appalachian Trail is subject to many of 

the same environmental problems that threaten natural areas 

in other places. Threats to the health of the Appalachian Trail 

environment include atmospheric ozone; atmospheric deposition of sulfur, nitrogen, and mercury; impaired visibility; pressure on rare and endangered wildlife and vegetation; invasive 

species; climate change and variability; and changes in land 

use; particularly from encroaching development (Shriver and 

others, 2005).

Delineation of Study Area

The Appalachian Trail is delineated and protected by 

a right-of-way corridor typically extending about 500 ft 

on either side of the footpath. While the Appalachian 

Trail can be most narrowly defined as the area within this 

1000-ft-wide corridor, a broader area of interest was needed 

to capture as much relevant water-quality data as possible 

for a level 1 assessment of the quality of water resources in 

the Appalachian Trail environment. In consultation with the 

NPS, a discrete study area for this investigation was defined 

on the basis of hydrologic boundaries to provide a geographic 

scope with hydrologic relevance to the Appalachian Trail. This 

study area was specifically defined as the intersections of the 

boundaries of watersheds (10-digit hydrologic units) (U.S. 

Department of Agriculture, 2005) not more than 5 mi from 

the Appalachian Trail corridor. This area of interest is known 

as the HUC10 shell (Dieffenbach, 2011). The HUC10 shell, 

referred to as study area in this report, incorporates an area 

that is approximately 41,779 mi2 and extends approximately 

15 mi on either side of the Appalachian Trail; it is much wider 

in some places and narrower in others owing to the different 

sizes of the watersheds composing the boundary (fig. 1).

Geology

The distinctive rolling-to-mountainous topography of 

the Appalachian Mountains is the product of the geologic 

development of this region. Repeated mountain-building 

episodes resulting from continental collisions, followed by 

hundreds of millions of years of weathering and erosion, 

have shaped the Appalachian Mountains to its current 

conformations. This complex geologic history has resulted 

in rocks ranging in age from billions of years to about 

140 million years (National Park Service, 2008). The 

geology includes a range of rock types, from folded and 

faulted sedimentary rocks such as limestone, sandstone, and 

shale, to metamorphic rocks such as schist and gneiss, to 

extensive intrusive rocks such as granites, as well as localized 

volcanic rocks. North of central Pennsylvania, continental 

glaciation during the Pleistocene Era further sculpted the 

landscape, leaving behind features characteristic of glacial 

environments, including many ponds (National Park Service, 

2008). The underlying geology is important because it is a 

fundamental aspect of the region: variations in the weathering 

rates of differing types of rocks, combined with geologic 

features such as faults and folds, have a substantial effect 

on drainage patterns, slopes, elevations, and many other 

topographic features. Additionally, variations in mineralogy 

may substantially affect surface-water chemistry, especially in 

smaller watersheds where base flow may be dominant.
6 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 3. The percentage of forested land cover in the study area.

80° 75° 70°

45°

40°

35°

EXPLANATION

Appalachian National 

Scenic Trail

Study-area boundary

State boundary

United States

Canada

Forest cover, in percent

0 to 20

greater than 20 to 40

greater than 40 to 60

greater than 60 to 80

greater than 80 to 100

Atlantic Ocean

Saint Lawrence River

Lake Ontario

Lake Erie

Lake 

Huron

State-line boundaries from North American Political Boundaries layer

U.S. Geological Survey 1:10,000,000-scale digital data

Albers Conic projection, NAD 1983

Percentages of forested land cover

from the National Hydrography Dataset Plus

(U.S. Environmental Protection Agency, 2006b)

0 100 200 MILES

0 150 300 KILOMETERS
Introduction 7

Topography

High elevations and steep slopes generally characterize 

the relief of the land in the immediate vicinity of the 

Appalachian Trail. Considerable variation in elevation exists 

along the Appalachian Trail, ranging from 124 ft above sea 

level where it crosses the Hudson River at Bear Mountain, 

New York to 6,643 ft at Clingmans Dome in Tennessee 

(National Park Service, 2008). The highest elevations and 

steepest slopes are generally in northern New England and 

in the southern Appalachians, whereas the lowest elevations 

are in the states of New York, New Jersey, Pennsylvania, and 

Maryland. Along the Appalachian Trail, the high ridges of the 

Appalachian Mountains are occasionally dissected by major 

river valleys such as the valleys of the Hudson, Susquehanna, 

and Potomac, which are characterized by flat to rolling terrain. 

Precipitation and Temperature

The climate in the vicinity of the Appalachian Trail is 

highly variable owing to the substantial range in latitude, 

elevation, and prevailing weather patterns. Cool summers and 

very cold winters are common in the northern areas around 

the Appalachian Trail, whereas hot summers and temperate 

winters are common in the southern areas, even at high 

elevations. At the northern end of the Appalachian Trail in 

Maine, the mean annual temperature during the period 1971 

through 2000 was 3.9oC, and the mean annual precipitation 

was 39.0 in. (U.S. Department of Commerce, 2003). The 

mean daily temperature in Maine over this period ranged 

from -12.2oC in January to 18.3oC in July (PRISM Climate 

Group, 2006a). By comparison, the mean annual temperature 

at the southern end of the Appalachian Trail in north-central 

Georgia over the same period was approximately 15oC, and 

the mean annual precipitation was 55.9 in. (U.S. Department 

of Commerce, 2003). In Georgia, the mean daily temperature 

over this period ranged from 5oC in January to 25oC in 

July (PRISM Climate Group, 2006a). The mean annual 

precipitation along the Appalachian Trail was approximately 

52.0 in. during the period 1971 through 2000 (PRISM Climate 

Group, 2006b).

Figure 4. The Appalachian National Scenic Trail passing through an open field on Cross Mountain near Shady Valley, Tennessee. 

(Photograph published by permission of Nancy Gaudreau)
8 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Snowfall was measured between 1971 and 2000 at 12 

long-term weather stations in the study area (National Climate 

Data Center, 2005). The greatest annual snowfall during this 

period was observed at Mount Washington, New Hampshire, 

where there was a mean annual value of 26.3 ft of measurable 

snowfall (National Climatic Data Center, 2005). Excluding 

the exceptional snowfall at Mount Washington, mean annual 

snowfall measured at stations in the study area ranged from 

7.6 ft in Millinocket, Maine, to 0.82 ft in Knoxville, Tennessee 

(National Climatic Data Center, 2005). Variation in snowfall 

appears to be related primarily to latitude, although elevation 

and other climate factors also affect total annual snowfall.

In general, temperature and precipitation both increase 

from north to south along the Appalachian Trail. However, 

extreme climatic variations over small distances in the 

Appalachian Mountains result from local topographic and 

orographic effects. One example is Mount Washington in 

New Hampshire, which has a mean annual precipitation 

of 102 in. at the summit (elevation 6,259 ft), while Berlin, 

N.H. (elevation 928 ft), a town only 18 mi away, has an 

average annual precipitation of 40.0 in. (U.S. Department of 

Commerce, 2003). 

Hydrology

The Appalachian Trail crosses about 1,700 streams and 

100 rivers from Maine to Georgia (fig. 6). Most of these 

streams are ‘low-order’ intermittent, first-, and second-order 

streams (Matt Robinson, National Park Service, written 

commun., 2006). These low-order streams are of particular 

interest because they are considered to be representative of the 

forested, mountainous, and high-elevation terrain that characterizes most of the Appalachian Trail environment. Larger 

streams and rivers—such as the Connecticut, the Hudson, and 

Figure 5. The Appalachian National Scenic Trail on Franconia Ridge, near Franconia, New Hampshire. (Photograph courtesy of 

Ann Chalmers, U.S. Geological Survey)
Introduction 9

the Potomac—are typically at lower elevations, and because 

the water quality is reflective of larger drainage basins and 

multiple contributing land uses that originate outside of the 

Appalachian Trail environment, they are not necessarily 

characteristic of the Appalachian Trail water resources. Consequently, these large stream and rivers, while important are 

beyond the scope of this report.

Physiographic and Ecological Divisions

Physiographic provinces are large-scale divisions that 

represent the topographic expression of the land surface and 

the geology and geologic history of a region (Fenneman and 

Johnson, 1946). Each province exhibits specific characteristics 

resulting from distinct combinations of geology, hydrology, 

precipitation, and temperature. Consequently, these provinces provide general geographic areas that help to describe 

variations in the environment within the study area. The 

Appalachian Highlands Physiographic Division encompasses 

the entire study area, and within this division are six physiographic provinces (from north to south along the Appalachian 

Trail): New England, St. Lawrence Valley, Valley and Ridge, 

Appalachian Plateaus, Blue Ridge, and Piedmont. The St. 

Lawrence Valley Physiographic Province only intersects a 

very small area of the study area in west-central Vermont. 

This province does not represent any significant spatial region 

of the Appalachian Trail study area and was therefore not 

included in the following discussion. The five physiographic 

provinces that do represent the Appalachian Trail study area 

are listed in table 1.

A similar but more detailed classification scheme provided by the USFS uses the concept of ecological subregions 

to incorporate the distinctive biological and ecological aspects 

of the landscape with the physical features at several levels 

Figure 6. A first-order stream, typical of the high-elevation streams that are crossed by the Appalachian National Scenic Trail. 

Brokenback Run is a tributary to the Hughes River near Nethers, Virginia. (Photograph courtesy of Jason Pope, U.S. Geological Survey)
10 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia Table 1. Description of landscapes, geology, and primary land cover for physiographic provinces and U.S. Forest Service ecological sections.—Continued Physiographic province1 U.S. Forest Service ecological section2 Landscape Geology Primary land cover

New England

Aroostook Hills and 

Lowlands

Gently rolling outwash plain with scattered low mountains. Highly modified by 

glaciation.

Sometimes weakly metamorphosed sedimentary formations, including sandstones, 

limestones, and shales.

Ranges from boreal conifers to broadleaf 

deciduous trees.

Maine–New Brunswick 

Foothills and Lowlands

Broad central plain with areas of gently sloping hills and low, rounded mountains. Sedimentary rocks with intruded granites. Spruce-fir and maple, beech, birch.

Central Maine Coastal and 

Embayment

Glacially scoured, dissected plain. Flat to 

gently rolling.

Metasedimentary and metavolcanic, with 

scattered granitic plutons.

Spruce-fir, mix of oak, hickory, maple, 

beech, and birch.

White Mountains Dissected highlands with rounded mountains 

and many glacial features.

Metasedimentary rocks, including quartzite, 

slate, and schist, intruded by extensive igneous areas including granite, diorite, gabbro, and basalt.

Spruce-fir, maple, beech, birch, and aspen.

Vermont–New Hampshire 

Upland

Maturely dissected plain with open, low 

mountains and isolated hills.

Metamorphosed sedimentary rocks such as 

quartzite, slate, and schist, as well as areas of gneiss and a band of volcanic rocks.

Maple, beech, birch, and aspen.

Green–Taconic–Berkshire 

Mountains

Ranges from nearly flat-topped plateaus with 

scattered isolated hills to sharp ridges with deep valleys. Previously glaciated.

Quartzite, schist, metavolcanics, gneiss, and 

amphibolite.

Maple, beech, birch, and aspen.

Lower New England Broad, hilly plateaus of lower elevations. Complex mix of sedimentary, igneous, and 

metamorphic rocks.

Mix of oak, hickory, maple, beech, birch, 

aspen, and pine.

Valley and Ridge

Hudson Valley Lowland formed from glacial lake plain, 

bordered by high escarpments.

Mix of carbonates, shales, siltstones, and 

sandstones, with areas affected by metamorphism.

Mix of maple, beech, birch, oak, hickory, 

and aspen.

Northern Ridge and Valley Broad parallel ridges and valleys trending 

from northeast to southwest.

Carbonates underlying valleys separated by 

low sandstone ridges.

Mix of oak and hickory.

Allegheny Mountains Dissected plateau resulting in landscape of 

sharp ridges, low mountains, and narrow valleys.

Sedimentary and metamorphic units, including sandstones, carbonates, siltstones, and 

shales.

Mix of oak, hickory, maple, beech, and 

birch.

Central Ridge and Valley Maturely dissected landscape of open hills 

with folded, faulted, and uplifted belt of parallel valleys and ridges.

Sedimentary rock formations, dominated by 

carbonates.

Small areas of remaining natural forest 

include oak, hickory, pine, and white, red, and jack pine. Agricultural and urban land cover is common.
Introduction 11

Table 1. Description of landscapes, geology, and primary land cover for physiographic provinces and U.S. Forest Service ecological sections.—Continued

Physiographic 

province1

U.S. Forest Service 

ecological section2 Landscape Geology Primary land cover

Appalachian Plateaus

Catskill Mountains Previously glaciated, deeply dissected 

plateau of mountainous terrain, with many peaks above 3,000 feet.

Fine sandstones, conglomerates, siltstones, 

and shales.

Mix of maple, beech, birch, oak, and 

hickory.

Northern Glaciated 

Allegheny Plateau

Previously glaciated, dissected plateau of 

rounded ridges and moderate relief.

Sedimentary, including sandstones, siltstones, and shales. Mix of maple, beech, birch, oak, hickory, and aspen.

Northern Cumberland 

Mountains

Long mountains and dissected uplands. Flat-lying sandstone units, incised by erosion. Mix of oak and hickory.

Blue RidgeBlue Ridge Mountains System of high ridges and peaks separated by narrow valleys. Southern section is much wider and has higher mountains. Mostly metamorphic rocks such as schist and gneiss, with some intrusive rocks such as granites and pegmatites, and occasional volcanics. Deciduous to mixed forest at lower eleva- tions, with distinctive spruce-fir forest at high elevations.Piedmont

Northern Appalachian 

Piedmont

Dissected plain extending from mountains 

to coast. Hilly to rolling, with a few high ridges.

Combination of sedimentary and mixed 

metamorphic rocks including marble, quartzite, slate, schist, and gneiss.

Oak, hickory and pine.

Southern Appalachian 

Piedmont

Dissected, irregular plain. Slightly rolling, 

with isolated hills and low mountains.

Mostly highly metamorphosed crystalline rocks weathered into deep, infertile, 

clayey soils.

Forests of oak-pine and loblolly-shortleaf 

pine. Cultivated agricultural areas are common.

1 Physiographic provinces are from Fenneman and Johnson, 1946.2 U.S. Forest Service ecological sections and descriptions are from Keys and others, 1995.
12 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

of geographic resolution (Keys and others, 1995). Of most 

interest to the current project were the ecological sections, 

which are described by Keys and others (1995) as “large 

land areas of relatively homogeneous physical and biological components that interact to form environments of similar 

productive capabilities, response to disturbances, and potential 

for resource management”; ecological sections defined by the 

USFS (Keys and others, 1995) are referred to in this report 

as ecosections. These ecosections are useful for describing 

the Appalachian Trail environment in more detail than that 

provided by the more general physiographic provinces. The 

study area intersects 17 ecosections mapped by Keys and others (1995). These ecosections are described in table 1, where 

they are presented in groups corresponding to physiographic 

province. The ecosections are shown in figure 7.

The New England Physiographic Province encompasses 

the Appalachian Trail study area from Maine to southern New 

York. Much of this province is characterized by a relatively 

cool climate because of both northern latitudes and high 

elevations. Winters are long with continual snow cover. This 

province includes several broad river valleys as well as peaks 

that are moderate in elevation (over 4,920 ft) with many peaks 

above treeline (Keys and others, 1995). The White Mountains 

of New Hampshire include the highest elevations on the 

Appalachian Trail north of Virginia, with Mt. Washington 

reaching over 6,200 ft (Keys and others, 1995). The 

underlying geology in the New England Physiographic 

Province is quite complex, resulting from multiple episodes 

of sedimentation, metamorphism, and intrusion, followed by 

extensive shaping of the landscape by glaciation. Ecosections 

within the New England Physiographic Province describe 

local ecological landscapes, with primary distinctions 

resulting from differences in geology, elevation, and the 

influence of coastal climatic conditions. Within the study area, 

the New England Physiographic Province includes seven 

ecosections: Aroostook Hills and Lowlands, Maine–New 

Brunswick Foothills and Lowlands, Central Maine Coastal 

and Embayment, White Mountains, Vermont–New Hampshire 

Upland, Green–Taconic–Berkshire Mountains, and Lower 

New England.

The Valley and Ridge Physiographic Province encompasses much of the western highlands of the Appalachian 

Mountains from New York to Georgia. Geologically, this 

province is characterized by folded and faulted sedimentary 

rocks. In general, the landscape is one of moderately high and 

narrow ridges approximately 1,500 to 3,500 ft in elevation and 

separated by long, wide valleys, with both trending northeast 

to southwest, approximately parallel to the Appalachian Trail 

(Keys and others, 1995). The ridges are formed by relatively 

resistant sandstone, and the valleys are underlain by shale 

and carbonate rocks (Keys and others, 1995). The pattern of 

ridges and valleys results in a trellis-style drainage pattern for 

streams and rivers of this province. Within the study area, the 

Valley and Ridge Physiographic Province includes four ecosections: Hudson Valley, Northern Ridge and Valley, 

Allegheny Mountains, and Central Ridge and Valley.

The Appalachian Plateaus Physiographic Province 

is in southern New York and Pennsylvania and also along 

the southern part of the Virginia–West Virginia border. The 

Appalachian Trail never passes through the Appalachian 

Plateaus, but the province intersects the study area on the 

western edge. The Appalachian Plateaus are structural plateaus 

formed from relatively flat-lying sedimentary rocks that have 

been dissected by streams into an area of high relief. The 

northern section has been glaciated. Within the study area, the 

Appalachian Plateaus Physiographic Province encompasses 

three ecosections: Catskill Mountains, Northern Glaciated 

Allegheny Plateau, and Northern Cumberland Mountains.

The Blue Ridge Physiographic Province extends from 

central Pennsylvania to Georgia and is traversed by the 

Appalachian Trail over most of that distance, except for a large 

section in southwestern Virginia where the Appalachian Trail 

passes into the Valley and Ridge. On its eastern boundary, the 

Blue Ridge is distinguished by a steep escarpment separating 

it from the Piedmont province to the east, with relief of 1,000 

to 1,600 ft in many places along this boundary (Keys and 

others, 1995). The Blue Ridge province is a narrow band (less 

than 12 mi wide) in its northern section and is characterized by 

a chain of relatively high mountain peaks ranging in elevation 

from approximately 3,000 to 4,000 ft and underlain primarily 

by metamorphic rocks, along with some plutonic and volcanic 

rocks, all highly resistant to weathering (Keys and others, 

1995). The Blue Ridge province is much wider (approximately 

75 mi) in the southern section, including areas in North 

Carolina, Tennessee, and Georgia, and is characterized by a 

system of high ridges forming several distinct mountain ranges 

separated by relatively narrow valleys. Most of this portion 

of the Blue Ridge province is underlain by metamorphic 

rocks such as gneiss and schist, with some intrusive rocks 

such as granites and pegmatites, and occasional volcanics 

(Keys and others, 1995). In this southern section, the Blue 

Ridge province includes numerous peaks and ridges with 

elevations exceeding 4,900 ft. The highest mountains of the 

Appalachian Trail are in this part of the province, including 

Clingmans Dome in Tennessee (Keys and others, 1995). This 

province includes some distinctive ecological environments, 

known as mountain balds (fig. 8). Within the study area, the 

Blue Ridge Physiographic Province includes only the Blue 

Ridge Mountains ecosection, which consists of deciduous 

to mixed forests at lower elevations and distinctive sprucefir forests at elevations above 4,900 ft (Keys and others, 

1995). Many lower slopes of the Blue Ridge Mountains were 

cleared for agriculture in the 1800s, and most areas were 

selectively logged by the early 1900s (Keys and others, 1995), 

though some isolated areas of old-growth forest remain. The 

high elevations and steep slopes of this ecosection result in 

considerable orographic variations in temperature 

and precipitation.

The Piedmont Physiographic Province comprises the 

eastern foothills and lowlands adjacent to the high mountains 

of the Blue Ridge province immediately to the west. The 

Piedmont province is not crossed by the Appalachian Trail 
Introduction 13

Figure 7. U.S. Forest Service ecological sections (ecosections) that intersect the study area.

Aroostook Hills 

and Lowlands

Maine-New 

Brunswick 

Foothills 

and Lowlands

Central Maine Coastal

and Embayment

Northern Appalachian Piedmont

Central Ridge Southern Appalachian Piedmont and Valley

Northern Cumberland Mountains

Catskill 

Mountains

White Mountains

Lower New 

England 

Blue Ridge Mountains

Allegheny Mountains

Northern Ridge and Valley

Northern Glaciated 

Allegheny Plateau

Hudson Valley

Vermont-New Hampshire Upland

Green-Taconic-Berkshire Mountains

80° 75° 70°

45°

40°

35°

EXPLANATION

Appalachian National Scenic Trail

Study-area boundary

State boundary

Ecosections (variously colored)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

U.S. Forest Service ecological sections from Keys and others (1995)

Physical-map background from the National Park Service

Natural Earth physical map, available online from ESRI (2009)

Atlantic Ocean

Lake Ontario

Lake Erie

Lake 

Huron

0 100 200 MILES

0 150 300 KILOMETERS
14 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 8. The Appalachian National Scenic Trail passing over Little Hump in North Carolina through the region known as the “balds.” 

(Photograph courtesy of Ann Chalmers, U.S. Geological Survey)
Introduction 15

but is on the eastern edge of the study area from southern 

New York to Georgia. The terrain of the Piedmont province 

ranges in elevation from approximately 330 to 1,640 ft and 

is underlain by metamorphic and igneous rocks that are the 

remnants of the tectonic events that formed the Appalachian 

Mountains (Keys and others, 1995). Hydrologically, this 

region is traversed by a number of wide river valleys that drain 

the eastern side of the Appalachians. Within the study area, 

the Piedmont province includes the Northern Appalachian 

Piedmont and Southern Appalachian Piedmont ecosections.

Previous Investigations

Although no assessment of the water quality along the 

entire Appalachian Trail has been completed, water quality has 

been the focus of numerous investigations within or near portions of the Appalachian Trail. While too many studies have 

been done to allow a review of each in this report, results from 

some of the more comprehensive and (or) ongoing investigations can be summarized. Many of these studies have focused 

on the affects of acid deposition as it relates to the acidification of surface-water bodies and the subsequent degradation 

of aquatic ecosystems. Generally, studies have found that the 

combination of regionally high inputs of acidic deposition, 

coupled with the generally low ionic strength of the surface 

waters and base-poor soils, makes the water resources of the 

Appalachian Mountains and nearby areas vulnerable to the 

detrimental effects of acidic deposition. Assessment of water 

quality conducted near regions of the Appalachian Trail have 

also correlated variations in land use, such as higher percentages of agricultural land or developed land, with variations in 

water quality. 

The acidification of surface waters by acid deposition in 

many areas near the Appalachian Trail has been well documented. Driscoll and others (2001) reported that 41 percent 

of the lakes in the Adirondack Mountains and 15 percent of 

the lakes in New England have exhibited chronic or episodic 

acidification. Furthermore, they reported that 83 percent of 

affected lakes are acidic because of acidic deposition. Kahl 

and Scott (1988) documented the significant role of atmospheric deposition in the acid-base chemistry of high-elevation 

lakes in Maine. In addition, it was concluded that lakes in 

Maine at elevations higher than approximately 2,000 ft were 

more dilute, less buffered, and probably more vulnerable to 

acidic deposition than low-elevation lakes in Maine. 

Acid-base chemistry in small streams in the Appalachian 

Mountains of Virginia (including Shenandoah National Park 

(Sullivan and others, 2004; Webb and others, 2004; Cosby 

and others, 2006; Rice and others, 2007) and the Blue Ridge 

Mountains of North Carolina and Tennessee including Great 

Smoky Mountains National Park and Coweeta Long-Term 

Ecological Research area (Cook and others, 1994; Robinson 

and others, 2008; John Schwartz, University of Tennessee, 

Department of Civil and Environmental Engineering, written 

commun., 2008; Cai and others, 2009) has been studied for 

years, and the effects of acidic deposition have been well 

documented. Approximately 93 percent of streams in the 

western mountains of Virginia were classified as sensitive to 

the effects of acidic deposition, 49 percent were classified as 

extremely sensitive, and 10 percent were classified as acidic 

(Charles and Christie, 1991). Of 54 low-order streams and 

67 lakes sampled in the southern Blue Ridge Mountains, no 

surface-water bodies were classified as acidic, although the 

waters of this region also have low ionic strength and are 

sensitive to acidic inputs (Charles and Christie, 1991). 

Surface waters that are classified as acidic or sensitive 

to acidic deposition are of interest because of the negative 

effects that acidic water can have on terrestrial and aquatic 

ecosystems. Seasonal and (or) event-driven increases in 

discharge that temporarily depress ANC in a water body are 

collectively referred to as episodic acidification. The occurrence and effects of episodic acidification have been well 

documented in surface waters in the Northeast (Driscoll, 1985; 

Wigington and others, 1996; Baker and others, 1996; Baldigo 

and Murdoch, 1997; Driscoll and others, 2001; Lawrence and 

others, 2004), in the Blue Ridge Mountains (Hyer and others, 

1995; Rice and Bricker, 1995; Rice and others, 2005; Cosby 

and others, 2006), and in the Great Smoky Mountains National 

Park (Deyton and others, 2009; Neff and others, 2008). One 

way that repeated exposure to episodic acidification affects 

terrestrial ecosystems in the Appalachian Mountains is that 

the increased concentration of anions in acidic deposition 

leaches and depletes base cations from soils (Lawrence, 2002; 

Bailey and others, 2005; Cosby and others, 2006; Elias and 

others, 2009) and researchers have shown that depletion of 

base cations from soil has negatively affected forest health 

(Driscoll and others, 2001; Bailey and others, 2005; Elias and 

others, 2009). One effect of episodic acidification on aquatic 

life is the decrease in the ANC or pH can facilitate the release 

of aluminum from the soil, specifically monomeric aluminum, which can be toxic to fish (Driscoll, 1985; Baldigo and 

Murdoch, 1997). Studies conducted in the Northeastern United 

States to investigate the harmful effects of inorganic monomeric aluminum on brook trout (Salvelinus fontinalis) reported 

both temporary and long-term harmful effects on fish populations (Baker and others, 1996; Baldigo and Murdoch, 1997). 

Neff and others (2008) demonstrated the detrimental effects of 

episodic acidification on the health of brook trout (Salvelinus 

fontinalis) in the Great Smoky Mountains National Park.

Rice and others (2005) developed a model to predict 

the vulnerability of streams in Shenandoah National Park to 

episodic acidification. The model indicated that large areas of 

the park are vulnerable to sustained intervals of episodic acidification that could be harmful to fish populations, and that the 

geology, elevation, and size of the drainage area are effective 

predictors of susceptibility to episodic acidification. Sullivan 

and others (2007) used ANC to evaluate variations in the 

spatial distribution of acid-sensitive and acid-affected streams 

in relation to watershed features in the southern Appalachian 

Mountains. Findings from this study suggest that elevation, 

lithology, size of the drainage area, and forest type can be useful predictors of acid-sensitive and acid-affected watersheds. 
16 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Since the passage of the Clean Air Act Amendments 

of 1990 (CAAA), the responses of surface-water-chemistry 

in acid-sensitive regions along the Appalachian Trail to 

reductions in sulfur dioxide and nitrogen oxides imposed 

by the CAAA have been studied. The USEPA’s Acid Rain 

Program has reported substantial reductions of sulfur 

dioxide and nitrogen oxides in atmospheric deposition (U.S. 

Environmental Protection Agency, 2010a). Researchers’ have 

examined the reactions of surface waters to these reductions in 

acidic deposition, and reported that concentrations of sulfate 

and, to a lesser extent, nitrate in surface water decreased 

after sulfate and nitrate in deposition had decreased (Driscoll 

and others, 1998; Driscoll and others, 2003; Stoddard and 

others, 2003; Kahl and others, 2004; Webb and others, 2004; 

Monteith and others, 2007; U.S. Environmental Protection 

Agency, 2010a). Many of these studies assessed the recovery 

of surface waters to changes in atmospheric deposition as 

reflected by increases in ANC and (or) pH coupled with 

decreases in concentrations of sulfate. Stoddard and others 

(2003) and Kahl and others (2004) reported that the response 

rates of surface waters varied and lagged behind decreases in 

deposition, but that surface waters with the lowest ANC and 

pH gave the largest and most rapid response. 

These studies, which measured the responses of 

surface-water-chemistry to reductions in acidic deposition 

from the CAAA, also demonstrated that these measures 

of change (increases in ANC and (or) pH and decreases 

in concentrations of sulfate) could be attributed to or be 

impeded by other environmental alterations. Stoddard and 

others (2003) and Rosfjord and others (2007) both reported 

that in the glaciated regions of the Northeast, concentrations 

of calcium and magnesium in soil have continued to decline 

despite the reduced input of anions from acidic deposition. 

Rosfjord and others (2007) noted that increasing surface-water 

concentrations of chloride caused by road-salting practices 

have altered the acid-base chemistry in affected watersheds, 

and that this interaction is complicating the assessment of the 

response of surface waters to changes in acidic deposition. 

Stoddard and others (2003) noted that increases in the natural 

organic acidity of surface waters also is complicating the 

assessment of recovery since passage of the CAAA. Monteith 

and others (2007) determined that increases in concentrations 

of dissolved organic carbon were proportional to decreases 

in the deposition of sulfate and sea salt. Webb and others 

(2004) reported that in the mountains of western Virginia, 

sulfate deposition in precipitation decreased by approximately 

40 percent from 1995 to 2000, although concentrations of 

sulfate in streamwater did not decline to a similar extent. Their 

findings corroborate and refine the conclusion from Kahl 

and others (2004) that the retention of sulfur in watershed 

soils in some regions of western Virginia affected the 

apparent disconnect between changes in sulfate deposition 

and concentrations of sulfate in streamwater. Furthermore, 

defoliation caused by the gypsy-moth infestation in the 

mid-1980s to mid-1990s may confound the interpretation 

of trends in ANC over time (Webb and other, 2004). The 

defoliation and subsequent recovery from the infestation 

produced a temporary increase and then a decrease in nitrate 

concentrations that likely caused a corresponding decrease and 

increase in the ANC. They concluded that it would be difficult 

to discern what respective proportions of the recent increases 

in ANC in this region could be attributed to the recovery 

from the gypsy-moth infestation and the reductions in 

sulfate deposition. 

Hickman and Fischer (2007) and Siemion and Murdoch 

(2010) summarized streamwater quality in the Delaware 

Water Gap National Recreation area in Pennsylvania and New 

Jersey. Both studies reported positive correlations between 

water-quality constituents and the percentage of agricultural 

land cover in the drainage area. Specifically, Siemion and 

Murdoch (2010) showed that ANC and the concentrations of 

calcium, potassium, nitrate, total dissolved nitrogen, and dissolved phosphorus were correlated with the percentage of agricultural land cover. Hickman and Fischer (2007) also noted 

that wetlands in the Delaware River drainage area appeared to 

influence water quality in the Delaware Water Gap National 

Recreation area. Hickman and Fischer (2007) used linear 

regression to predict the differences in water quality between 

current (2002–2004) and future conditions.

Headwater stream chemistry is also important because 

of its subsequent effects on the water quality of downstream 

resources and aquatic communities. The effect of headwater 

streams on downstream water quality has been well documented (Alexander and others, 2007; Freeman and others, 

2007; Nadeau and Rains, 2007). Alexander and others (2007) 

used a mass-balance watershed model based on stream networks in the northeastern United States to demonstrate the 

substantial contribution that first-order, headwater streams 

have on higher order streams with respect to mean annual 

flows and solute transport. Findings from this work showed 

that hydrologic and biogeochemical processes in headwater 

streams were physically and biochemically connected to the 

water quality downstream. Furthermore, the high proportional 

total length of headwater streams in the total stream length of 

a typical river drainage system (commonly over two-thirds) 

underscores the profound influence of the water quality of 

headwaters streams on the ecological integrity of streams and 

rivers at local and regional scales (Freeman and others, 2007).

Sources of Water-Quality Data

Many different projects with unique objectives have 

collected water-quality data from sampling sites along the 

Appalachian Trail. One of the primary objectives in compiling 

this level 1 water-quality inventory was to assess water-quality 

data from sites along or near the Appalachian Trail for use 

in determining water-quality conditions representative of the 

Appalachian Trail environment. Focus was given to data that 

had been collected at first- and second-order streams near the 

Appalachian Trail. Data were retained for consideration if the 

record included spatial information (latitude and longitude) 
Sources of Water-Quality Data 17

and at least one water-quality constituent of interest, and if the 

data could be reasonably aggregated and compared with 

other datasets. 

The data compiled for this project were collected by 

Federal, State, and university water-quality research programs. 

Data sources include the USGS; the U.S. Environmental 

Protection Agency (USEPA); the NPS; the USFS; the 

National Science Foundation (NSF), including the Long-Term 

Ecological Research (LTER) Program; the Water Resources 

Research Center at the University of Massachusetts, Amherst; 

and the Department of Environmental Sciences at the 

University of Virginia. Water-quality data from all of these 

sources were obtained in a variety of electronic formats.

Initially, data were obtained from the USGS’s National 

Water Information System (NWIS) and USEPA’s STOrage and 

RETrieval (STORET) databases (including Legacy STORET) 

(Dean Tucker, National Park Service, written commun., 2008). 

NWIS and STORET are national data warehouses for chemical, physical, and biological data from water, sediment, and 

tissue samples. More than 10 million records of water-quality 

data from about 16,800 sampling sites within 20 mi of the 

Appalachian Trail were obtained for this project (table 2). The 

data obtained from NWIS and STORET constituted about 

95 percent of all data initially compiled and included chemical, physical, and biological data. Data were from numerous 

projects with different objectives, methods of collection and 

analysis, and scales of focus. The remaining (approximately 

5 percent) data were obtained from ten specific water-quality 

programs focused on areas near the Appalachian Trail. Many 

of these programs were designed to evaluate the effects of 

acidic deposition on surface-water resources. 

Acid Rain Monitoring Program

The Acid Rain Monitoring (ARM) project is a program 

of the Water Resources Institute of the Massachusetts Water 

Resources Research Center at the University of Massachusetts, 

Amherst. The ARM project began in 1983 for the purpose 

of determining the sensitivity of Massachusetts lakes and 

streams to acidic deposition and evaluating trends in acidification (Acid Rain Monitoring, 2008). The data obtained from 

this program consist of more than 3,100 water-quality records 

from approximately 70 sampling sites (table 2). Samples 

typically were analyzed for pH, major ions, ANC, and some 

trace elements. Findings from this program are summarized in 

Godfrey (1998).

Coweeta LTER Program

The Coweeta experimental forest is part of the NSF’s 

LTER Program, which supports long-term ecological research 

across a wide range of geographic scales. The LTER network 

includes 26 study areas primarily in the United States. Two 

of these study areas, Coweeta in North Carolina and Hubbard 

Brook in New Hampshire, are near the Appalachian Trail. 

The Coweeta LTER study area focuses on the effects of 

disturbance and environmental gradients on biogeochemical 

cycling, and on the underlying watershed ecosystem 

processes that regulate and respond to the ecological cycles. 

The USFS also conducts research at the Coweeta LTER site 

independently and in collaboration with the NSF’s LTER 

program. The USFS investigations primarily focus on the 

interaction between forest health and the water quality of 

streams. Coweeta furnished more than 13,000 water-quality 

records from 74 sampling sites (table 2). Samples typically 

were analyzed for pH, specific conductance, ANC, major 

ions, nutrients, and organic carbon. However, specific studies 

at Coweeta address many different facets of ecosystem 

interaction (Coweeta Long Term Ecological Research, 2010).

Hubbard Brook LTER Program

The Hubbard Brook experimental forest is in the White 

Mountain National Forest, New Hampshire. It is part of the 

NSF’s LTER program and is managed by the USFS Northern 

Research Station. Onsite research is broad based and includes 

studies relating to hydrology, biology, geology, and chemistry 

of the forest and its associated aquatic ecosystems (Likens, 

1985; Likens and Bormann, 1995). The data obtained from 

this program consist of 16,900 water-quality records from 

5 sampling sites (table 2). Samples typically were analyzed 

for pH, major ions, and nutrients. However, specific studies at Hubbard Brook also address many different facets of 

ecosystem interaction (Hubbard Brook Long Term Ecological 

Research, 2010).

Delaware Water Gap National Recreation Area

Water-quality data were collected from 13 small streams 

in the Delaware Water Gap National Recreation Area (New 

York, New Jersey, and Pennsylvania) from July 2002 to 

September 2003 (table 2). These streamwater samples 

were analyzed for ANC, major ions, nutrients, carbon, and 

aluminum at the USGS New York Water Science Center 

laboratory (Jason Siemion, U.S. Geological Survey, written 

commun., 2009).

Great Smoky Mountains National Park

There are two components to the Great Smoky 

Mountains National Park water-quality program: Noland 

Divide water-quality monitoring and a park-wide waterquality survey. The Noland Divide is in the middle of Great 

Smoky Mountains National Park near the border of North 

Carolina and Tennessee. It is a small (17.4 ha), forested, high 

elevation (5,500 to 6,300 ft) watershed. This watershed was 

selected for long-term monitoring because its geographic 

location, high elevation, and underlying geology tend to make 

the watershed vulnerable to the effects of acidic deposition 
18 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Table 2. Appalachian National Scenic Trail level 1 inventory of data sources used, project acronym, number of sampling sites, number 

of records, and the period of record for the water-quality data initially compiled.

[NPS, National Park Service; USEPA, U.S. Environmental Protection Agency; USFS, U.S. Forest Service; STORET, STOrage and RETrieval; USGS, U.S. 

Geological Survey]

Data source Appalachian Trail project 

data source acronym

Number of 

sampling sites

Number of 

records Period of record

Acid Rain Monitoring Program; Water Resources Institute of 

Massachusetts, Amherst

ARM 73 3,148 1983–2008

National Science Foundation’s Long-Term Ecological 

Research Program, North Carolina

Coweeta LTER 74 13,640 1998–2009

National Science Foundation’s Long-Term Ecological 

Research Program, New Hampshire

Hubbard Brook LTER 5 16,900 1963–2005

Delaware Water Gap National Recreation Area1 DEWA 13 10,815 2002–2003

Great Smoky Mountains National Park; the Noland Divide 

and the park-wide water-quality-monitoring programs; NPS

GRSM 92 55,636 1991–2007

Virginia Trout Stream Sensitivity Study; University of 

Virginia, NPS, USEPA, USFS, Virginia Department of 

Game and Inland Fisheries, and Trout Unlimited

VTSSS 353 5,148 2002–2003

White Mountain National Forest, New Hampshire 

(Hornbeck and others, 2001)

WMNF 210 78,781 1967–1999

Environmental Monitoring and Assessment Program; USEPA EMAP 225 20,273 1993–1998

Temporally Integrated Monitoring of Ecosystems Project and 

Long Term Monitoring Project; USEPA

TIME/LTM 618 280,911 1979–2005

National Stream Survey; USEPA NSS 274 46,586 1985–1986

Wadeable Stream Assessment; USEPA WSA 293 6,264 2004

STORET Legacy Data Center; USEPA Legacy STORET 7,385 6,296,007 1939–1998

STORET Data Warehouse; USEPA STORET 3,491 1,083,586 1968–2007

National Water Information System; USGS NWIS 3,698 2,643,058 1923–2008

1

 Water-quality data from the USGS New York Water Science Center (Jason Siemion, U.S. Geological Survey, written commun., 2009)
Sources of Water-Quality Data 19

(Cook and others, 1994; Robinson and others, 2008; John 

Schwartz, University of Tennessee, Department of Civil and 

Environmental Engineering, written commun., 2008; Cai and 

others, 2009). The Great Smokey Mountain park-wide water 

quality-monitoring project began in October 1993 and initially 

collected water samples from 367 sampling sites throughout 

the park that represented a range of elevations, geology 

types, and disturbance histories. Throughout the project, 

water-quality samples were collected at various intervals and 

subsets of sampling sites during base-flow conditions. The 

data obtained from these two programs consist of more than 

55,000 water-quality records from 92 sampling sites (table 2). 

Samples typically were analyzed for pH, specific conductance, 

ANC, major ions, nutrients, and some trace elements. Findings 

from both projects are summarized in annual NPS reports 

and various research publications including: Cook and others 

1994; Neff and others, 2008; Robinson and others, 2008; Cai 

and others, 2009; Deyton and others, 2009.

Virginia Trout Stream Sensitivity Study (VTSSS)

The Virginia Trout Stream Sensitivity Study (VTSSS) 

collects data related to water chemistry in the Shenandoah 

National Park and the mountains of western Virginia for the 

general purpose of monitoring the quality of native brook trout 

streams. VTSSS data collected within Shenandoah National 

Park is coordinated with ongoing broad-based monitoring of 

water quality by the Shenandoah Watershed Study (University 

of Virginia, 2010). The data obtained from the VTSSS consist 

of more than 5,100 water-quality records from 353 sampling 

sites (table 2). Samples typically were analyzed for pH, specific conductance, ANC, and major ions. 

White Mountain National Forest

In 2001, the USFS compiled a database of water-quality 

data for the White Mountain National Forest, located in central New Hampshire (Hornbeck and others, 2001). The data 

obtained from this study consist of more than 78,700 waterquality records from 210 sampling sites (table 2). Samples 

typically were analyzed for pH, specific conductance, ANC, 

major ions, nutrients, and trace elements. 

Environmental Monitoring and Assessment 

Program (EMAP)

The USEPA initiated the Environmental Monitoring and 

Assessment Program (EMAP) in the late 1990s to monitor 

and assess the status and trends in ecological resources of the 

United States. The program evolved into a research program 

aimed at the development of tools for translating environmental-monitoring data from multiple spatial and temporal scales 

into assessments of current ecological conditions and forecasts 

of risks to natural resources. EMAP data used in this project 

were from small streams (first- through third-order streams) 

located within the study area. The data obtained from this program consist of more than 20, 200 water-quality records from 

225 sampling sites (table 2). Samples typically were analyzed 

for pH, specific conductance, ANC, major ions, nutrients, and 

organic carbon.

Temporally Integrated Monitoring of Ecosystems 

and Long Term Monitoring Program (TIME/LTM)

The USEPA’s Temporally Integrated Monitoring of 

Ecosystems (TIME) project was developed as a special study 

within EMAP. The focus of the TIME program is to track the 

trends in the acid/base chemistry of acid-sensitive lakes in the 

northeast and streams in the central Appalachians (Stoddard 

and others, 1996). The primary objective of the Long Term 

Monitoring (LTM) program is to detect long-term trends in 

the acid/base status of lakes and streams across a gradient of 

acidic deposition nationally. The LTM network consists of a 

subset of lakes and streams that are particularly sensitive to 

acidity with most sampling-site records extending back to the 

early 1980s. The TIME and LTM are currently (2011) ongoing studies, and their data are commonly used together (U.S. 

Environmental Protection Agency, 2010b). The data obtained 

from these two programs consist of more than 280,000 waterquality records from 618 sampling sites (table 2). Samples 

were typically analyzed for pH, specific conductance, ANC, 

major ions, nutrients, organic carbon and inorganic carbon. 

National Stream Survey Program

The USEPA’s National Stream Survey program was 

designed to classify and characterize streams that are presently 

acidic or that have low ANC. In addition, the National Stream 

Survey program sought to identify streams appropriate for 

intensive long-term monitoring. The data obtained from this 

program consist of more than 46,500 water-quality records 

from 274 sampling sites (table 2) (U.S. Environmental 

Protection Agency, 2010c). Samples typically were analyzed 

for pH, specific conductance, ANC, major ions, nutrients, 

organic carbon, and inorganic carbon. 

Wadeable Stream Assessment Program

The USEPA’s Wadeable Stream Assessment program collected data for water-quality, biological, and physical-attribute 

assessments from wadeable streams and rivers across the 

United States (U.S. Environmental Protection Agency, 2006c). 

For this program, wadeable streams were defined as firstthrough fifth-order streams. The goal of the Wadeable Stream 

Assessment was to report on the condition of small streams 

in the United States and to establish a baseline with which to 

compare results from future studies. The data obtained from 

this program consist of more than 6,200 water-quality records 

from 293 sampling sites (table 2). 
20 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Methods of Analysis

Water-quality data and ancillary spatial data were 

compiled from numerous sources to develop a comprehensive inventory appropriate for describing the water quality of 

headwater streams along the Appalachian Trail. An inventory 

and assessment of the water quality of headwater streams of 

the Appalachian Trail requires an explicit definition of what 

is meant by the phrase “water quality of the Appalachian 

Trail.” A careful consideration of project objectives and an 

initial evaluation of data suggested that the specific area of 

interest should be larger than the immediate environment of 

the approximately 1000-ft-wide Appalachian Trail corridor 

to include relevant water-quality data. However, it also was 

apparent that inclusion of all water-quality data from first- and 

second-order streams within the study area would be too broad 

to be useful. Spatial data that delineates hydrologic boundaries and spatial data that characterizes environmental landscape 

attributes were used together to develop a method of site 

selection that resulted in an inventory of water-quality data 

representative of headwater streams along the Appalachian 

Trail. Environmental attributes also were used to describe possible anthropogenic and natural factors that may be influencing water quality. Water-quality data selected for inclusion in 

the resource characterization were aggregated to minimize the 

influence of intensively monitored sites and areas. The water 

quality of headwater streams along the Appalachian Trail was 

described through the use of computed summary statistics, 

comparisons of variations in summary statistics along the 

Appalachian Trail, and associations between water quality and 

environmental attributes. 

Quality Assurance and Compilation of WaterQuality Data

Prior to analyzing the water-quality datasets described 

above, several quality-assurance measures were applied to 

identify potential errors in the reported water-quality values 

and to minimize issues that originated from combining data 

from multiple sources. Quality assurance steps taken to review 

the water-quality data included: removal of water-quality 

records determined to be inappropriate for use in analyses; 

assignment of an Appalachian Trail project site name to unify 

all records from the same sampling site; censorship of some 

nutrient values; and conversion of reported concentrations to 

standardized units.

Quality Assurance

Water-quality data were evaluated to determine if 

reported values were reasonable and appropriate for use in 

analyses. Three measures were used to determine if data were 

appropriate for use: comparison to USEPA criteria; comments 

or remark codes; and cation-anion balance. The USEPA has 

established typical ranges for many constituents and properties. These typical ranges, at one time, were used to screen 

data entered in STORET (National Park Service, 1998); all 

data were checked to ensure that they were within typical 

ranges. Water-quality values identified as suspect were then 

evaluated individually by comparing the values to other data 

from that site or similar nearby sites. Comments and remarks 

codes were evaluated to determine the quality of the reported 

value. Approximately, 16 percent of the samples selected had 

enough major ion data reported to calculate an ion balance. 

Ion balances were calculated on equivalent concentrations 

using procedures described by Hem (1992). Cation and 

anion concentrations were within 10 percent of each other 

for 93 percent of the sampling sites with sufficient data. The 

quality-assurance actions included:

• 255 records removed for exceeding the USEPA typical 

ranges,

• 43 records removed because the remarks code indicated that the value was compromised,

• 172 records of major ion data removed because the 

value was reported as zero, and

• 23 records removed because the cation/anion balance 

exceeded 10 percent.

These 493 water-quality records composed less than 

0.003 percent of the data initially obtained. 

Data Compilation

The uniqueness of each sampling site was evaluated 

relative to other nearby sampling sites through comparison of 

site-identification data, site names, and proximity. This step 

determined that approximately 10 percent of the sampling sites 

appeared in more than one of the datasets. A project-site name 

was created to unify all water-quality records from a sampling 

site. For the purposes of this quality-assurance step, sampling 

sites were considered identical if they had the same site name 

and were less than 330 ft apart. Sampling sites that had the 

same identifier and were more than 330 ft apart were retained 

as separate sampling sites. This method might have eliminated 

many duplications of sampling sites but also may have merged 

a small number of sampling sites that were actually unique. 

Considering the large number of sampling sites with data and 

the size of the study area, combining sampling sites in this 

manner probably affected the overall data-compilation effort 

to a minimal extent.

Data compiled for this study were from both unfiltered 

and filtered samples. Major ions, nitrate, and ammonia are 

generally in the dissolved form in these natural waters that 

are mainly in undisturbed landscapes. For this reason, data 

values from unfiltered (commonly referred to as total) and 

filtered (commonly referred to as dissolved) samples were 

combined for most constituents. More than 75 percent of 

major-ion samples used in this study were from filtered 
Methods of Analysis 21

samples. Approximately 68 percent of ammonia samples were 

from unfiltered samples, and more than 87 percent of nitrate 

samples were from filtered samples. All total nitrogen and 

total phosphorus values used in analysis were from unfiltered 

water samples.

The issue of multiple detection limits for each constituent is inherent in a compiled dataset from a variety of sources 

that includes analyses from 1923 through 2009 (median year 

= 1995). The minimum detectable concentration for a constituent is dependent on at least the following factors: the 

water matrix, sample-collection protocols, method of analysis, quality-control measures implemented by the analyzing 

laboratory, and objectives of the water-quality investigation. 

Concentrations below the minimum detectable concentration 

for a water-quality constituent are often censored and identified with a remark character indicating that the concentration 

is less than the minimum detectable concentration. Fewer than 

0.3 percent of major-ion concentrations and approximately 

28 percent of nutrient concentrations were reported as less 

than the respective minimum detectable concentrations. To 

the extent possible, reported values were retained and used as 

received. However, some nitrate and ammonia concentrations 

were reported as exceptionally low (less than 0.008 mg/L for 

nitrate and less than 0.01 mg/L for ammonia). These exceptionally low values were censored to improve the comparability of datasets by use of the following criteria:

• Concentrations of nitrate reported below 0.008 mg/L as 

N were set to less than 0.008 mg/L, the USGS National 

Water Quality Laboratory’s Long-Term Method 

Detection Level for nitrate (Childress, 1999). As a 

result, 3,835 concentrations of nitrate reported below 

0.008 mg/L were censored to less than 0.008 mg/L 

as N. 

• Concentrations of ammonia reported below 0.01 mg/L 

as N were set to less than 0.01 mg/L as N, the USGS 

National Water Quality Laboratory’s Long-Term 

Method Detection Level for ammonia (Childress, 

1999). As a result, 3,700 concentrations of ammonia 

reported below 0.01 mg/L as N were censored to less 

than 0.01 mg/L as N. 

The titration procedure used to measure ANC depends on 

whether the water is expected to be buffered primarily by carbonate solutes, most commonly carbonate and bicarbonate. In 

this case, the titration proceeds to theoretical pH endpoints for 

carbonate species (pH values near 8.3 for carbonate and 4.5 

for bicarbonate). The ANC of low-ionic-strength waters, like 

those in some regions along the Appalachian Trail, is generally 

presumed not to be controlled by the carbonate system; in this 

case, the Gran titration is used. The Gran titration measures 

the presence of species other than carbonate that contribute to 

ANC; the method requires detailed acidimetric data over the 

entire titration, is carried out to pH values of 3.5 or lower, and 

can result in a negative ANC value (Gran, 1952). 

Reported values of ANC were determined by a variety of 

titration procedures. For the purposes of this inventory, if the 

sample was unfiltered and a titration was performed, it was 

considered to represent ANC. Approximately 50 percent of 

the values of ANC were determined by using Gran titration, 

of which 85 percent were from the section of the Appalachian 

Trail south of Maryland. To use as much available data as 

possible and to provide information regarding ANC in the 

northern section of the Appalachian Trail, all ANC data were 

combined regardless of the titration procedure. More frequent 

occurrence of low or negative ANC values in the southern 

section compared to the central and northern sections of the 

Appalachian Trail may be an artifact of the higher percentage of ANC determined through the use of the Gran titration 

method in the southern section of the Appalachian Trail. 

Reported water-quality values were converted to ensure 

that units of concentrations were standardized and to ensure 

that the same species was analyzed for each constituent. 

Water analyses were initially reported primarily with four 

different units for concentration: micrograms per liter (μg/L), 

mg/L, μeq/L, and μmol/L. Water-quality constituents were 

converted as needed and are primarily summarized in mg/L. 

All ANC values are reported in μeq/L. Bicarbonate is reported 

as mg/L as bicarbonate. Ammonia, nitrate, and total nitrogen 

are reported as mg/L as nitrogen. Total phosphorus is reported 

as mg/L as phosphorus. Nitrogen and phosphorus species 

conversions were based on procedures from Mueller and 

others (2005).

Ancillary Data Sources

Two primary types of ancillary spatial information were 

used: spatial data delineating hydrologic boundaries, and 

descriptive spatial data that characterized attributes of the 

environment, such as land cover. Descriptive spatial data 

were particularly useful in determining that the environmental setting of nonadjacent sampling sites were very similar 

to the Appalachian Trail environment. Therefore, it is likely 

that the water quality also would be representative of the 

Appalachian Trail environment. Ancillary spatial datasets also 

were used to help determine differences in the environmental 

settings of sampling sites where water quality varied along the 

Appalachian Trail. The spatial datasets used include information pertaining to physiography, land cover, and atmospheric 

deposition. A list of spatial data sources used for hydrologic 

and environmental attributes is shown in table 3. 

Hydrologic Attributes

The extent of the study area and divisions within 

the study area were delineated by using the boundaries of 

hydrologic units (U.S. Department of Agriculture, 2005). 

Hydrologic-unit boundaries delineate successively smaller 

surface-water drainage areas of major rivers or the combined 

drainage areas of a series of rivers (Seaber and others, 1987). 

Hydrologic units used for this project include watersheds (also 

known as 10-digit hydrologic units) that were used to define 
22 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

the extent of the study area, and subregions (also known as 

4-digit hydrologic units) that were used to create subdivisions 

within the study area (fig. 9).

Delineation and characterization of the Appalachian 

Trail environment within the study area and characterization 

of the environmental setting of sampling sites was completed 

through the use of data from National Hydrography Dataset 

Plus (NHDPlus). NHDPlus is a suite of geospatial data 

products that have been developed to work in concert (U.S. 

Environmental Protection Agency, 2006a). The building 

blocks of NHDPlus were the medium-resolution National 

Hydrography Dataset (NHD), the National Elevation Dataset 

(30-meter), and the National Watershed Boundary Dataset. 

The fundamental feature of the NHDPlus dataset is the 

delineation of a catchment. A catchment is defined as the 

incremental drainage area for a single NHD hydrologic 

feature such as a stream segment (fig. 10). Stream segments 

and associated catchments are linked and nested so that the 

drainage area for a specific hydrologic feature includes its 

incremental drainage (catchment) area as well as the full 

cumulative drainage area upstream from that feature, including 

the headwaters (Johnston and others, 2009) (fig. 10). The 

NHDPlus geospatial database also contains derived physical 

attributes for each catchment, including slope, elevation of 

stream segments (hereafter referred to as stream elevation), 

and size of drainage area, as well as data integrated from other 

geospatial datasets, such as the National Land Cover Dataset 

(1992) (U.S. Geological Survey, 2000). Comparisons in 

differences in the size of drainage areas along the Appalachian 

Trail could not be assessed because of the varying resolution 

of the underlying hydrography data used in NHDPlus and the 

influence that this resolution disparity may have had in the 

delineation of catchment boundaries.

Catchments were used as the fundamental geographic 

units for this project because of the wealth of landscape 

data provided by NHDPlus for these small hydrologic units. 

Catchment boundaries were used to delineate and describe 

the Appalachian Trail environment, and water-quality data 

were aggregated and summarized by catchments. Two 

physical attributes of catchments (stream elevation and landcover information) were used to screen sites for inclusion 

in the water-quality summary and were tested as possible 

explanatory variables for observed variations in water-quality 

data. In addition, data for slope of the catchment, mean annual 

precipitation, and mean annual temperature were evaluated for 

correlations with environmental and water-quality variables. 

Strahler stream-order values available for every catchment 

through an NHDPlus extension were important in the siteselection process for defining first- and second-order streams. 

(Datasets that have been developed to provide additional 

information integrated with NHDPlus are referred to as 

data extensions.)

Table 3. Types and sources of ancillary data used in this study.

Data type Source

Hydrologic attribute data

NHDPlus U.S. Environmental Protection Agency, 2006

Boundaries of hydrologic units U.S. Department of Agriculture, 2005

Environmental attribute data

Ecological subdivision Keys and others, 1995

Stream elevation U.S. Environmental Protection Agency, 2006

Land-cover data U.S. Environmental Protection Agency, 2006

Slope U.S. Environmental Protection Agency, 2006

Elevation Gesch, 2007

Air temperature PRISM Climate Group, 2006a

Precipitation PRISM Climate Group, 2006b

Soils data (STATSGO2) U.S. Department of Agriculture, Natural Resource Conservation Service, 2006

Geologic data King and Beikman, 1974; Reed and Bush, 2005

Annual precipitation-weighted mean sulfate concentration National Atmospheric Deposition Program, 1994a

Annual precipitation-weighted mean nitrate concentration National Atmospheric Deposition Program, 1994b

Nutrient ecoregions U.S. Environmental Protection Agency, 2000
Methods of Analysis 23

Figure 9. Hydrologic subregions (variously colored) that intersected and were used as geographic subdivisions of the 

study area.

Delaware

Upper Tennessee

Potomac

Connecticut

Kanawha

Penobscot

Kennebec

Upper Hudson

Susquehanna

Lower 

Chesapeake

Androscoggin

Saco

Connecticut 

Coastal

Richelieu

Chowan-Roanoke

Merrimack

Alabama

Apalachicola

Lower Hudson-Long Island

Middle 

TennesseeHiwassee

Ogeechee-Savannah

80° 75° 70°

45°

40°

35°

EXPLANATION

Appalachian National Scenic Trail

United States

Canada

Study-area boundary

State boundary

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

Hydrologic subregions (4-digit HUCs)

from U.S. Department of Agriculture (2005)

0 100 200 MILES

0 150 300 KILOMETERS

Atlantic Ocean

Saint Lawrence River

Lake Ontario

Lake Erie

Lake 

Huron
24 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 10. Schematic diagram showing examples of the nested relation of National Hydrography Dataset Plus (NHDPlus) catchments 

with larger delineated hydrographic units such as subwatersheds, and drainage areas defined for a set of nested catchments.

EXPLANATION

Appalachian National Scenic Trail

Subwatershed boundary

Catchment boundaries

Cumulative drainage area

National Hydrography Dataset streamline

Sampling site 

Catchments that

compose the cumulative

drainage area to 

selected sampling sites 

(locations shown as black dots) 

Subwatershed divided into

catchments. Catchments are

the incremental drainage areas 

for NHD features such as 

stream segments

Subwatershed (approximately 

12-digit hydrologic unit) with

NHD stream lines
Methods of Analysis 25

Environmental Attributes

Ecosections defined by the USFS were used to group 

water-quality data and to relate spatial attributes to variations 

in water-quality data. Geologic data from Reed and Bush 

(2005) and King and Beikman (1974) were used to group 

catchments by major lithology type and evaluate variations 

in water quality. Concentrations of total nitrogen and total 

phosphorus were compared to USEPA nutrient criteria by 

nutrient ecoregions (U.S. Environmental Protection Agency, 

2000; 2002b). Concentrations of ammonia, nitrate, total 

nitrogen, and total phosphorus were compared to estimated 

background concentrations developed by the USGS 

(Dubrovsky and others, 2010). 

Environmental attributes from most of the following spatial datasets were assigned based on the attribute values at the 

geographic center of each catchment. Topographic elevation 

data used to evaluate water-quality variations associated with 

elevation were assigned from digital elevation maps (Gesch, 

2007). Land-cover data were obtained from NHDPlus, which 

contains information integrated from the National Land Cover 

Dataset from 1992. Mean annual precipitation and temperature data were obtained from the PRISM Climate Group 

(PRISM Climate Group, 2006a; b). Soils data were obtained 

from the Natural Resources Conservation Service‘s State 

Soil Geographic database (U.S. Department of Agriculture, 

2006). Soils data used in the analysis included average range 

in permeability, average range in bulk density, average range 

in organic matter content, average percentage of clay content, 

average percentage of silt content, and average percentage 

of sand content. Precipitation-weighted annual concentrations of sulfate and nitrate in precipitation were obtained from 

the National Atmospheric Deposition Program (NADP) as 

continuous rasters interpolated from measurements at NADP 

sites (National Atmospheric Deposition Program, 1994a, b). 

Continuous rasters of yearly estimated sulfate and nitrate 

deposition (in mass per unit area) were computed from NADP 

concentration rasters and PRISM estimated annual mean precipitation rasters (PRISM Climate Group, 2006b) by using a 

method developed by Latysh and Wetherbee (in press).

Site Selection

The evaluation and selection of available sampling sites 

for this study were based on the stream-order, the proximities 

of the sites to the Appalachian Trail, and the environmental 

settings of the sampling sites. Sampling sites were assigned to 

an NHDPlus catchment through GIS analysis, and the environmental setting of each sampling site was characterized by 

the physical attributes compiled from available spatial data for 

the catchment. All selected sampling sites were on first- and 

second-order streams as determined by available data from 

NHDPlus. 

All catchments that contained first- and second-order 

streams and directly adjacent to the Appalachian Trail were 

identified. Catchments defined as adjacent to the Appalachian 

Trail included those for which the catchment polygon geographically intersected the Appalachian Trail corridor in a GIS 

analysis. These catchments, hereafter called adjacent catchments, encompass the headwaters that drain the Appalachian 

Mountains along the Appalachian Trail and were considered to 

represent the hydrologic environment of the Appalachian Trail. 

There are 2,565 first- and second-order adjacent catchments in 

the Appalachian Trail study area. NHDPlus data were used to 

evaluate and describe physical landscape characteristics associated with the adjacent catchments and thereby characterize 

the hydrologic environment of the Appalachian Trail headwater streams (figs. 11 and 12A–D). 

The collective environment for all adjacent catchments 

was over 88 percent forested land, approximately 8 percent 

agricultural land, 2 percent open water or wetlands, and 1 percent developed land. However the Appalachian Trail environment differed widely along the trail. Adjacent catchments in 

the state of Maine were approximately 90 percent forested 

land, 7 percent water, and 3 percent bare rock. In contrast, 

the adjacent catchments in Pennsylvania and Maryland were 

approximately 65 percent forested land, more than 30 percent 

agriculture land, and more than 2 percent developed land. 

Approximately 25 percent of the length of the Appalachian 

Trail is in Virginia. The adjacent catchments in Virginia were 

89 percent forested land, 10 percent agricultural land, and less 

than 1 percent developed land. The adjacent catchments in the 

state of Georgia were more than 99 percent forested land. For 

this investigation, data collected from all sampling sites within 

adjacent catchments were retained for analysis because these 

sampling sites were considered to be representative of the 

hydrologic environment of the Appalachian Trail. A total of 

309 adjacent catchments contained at least one sampling site 

selected for water-quality analysis in this study.

Criteria for Selection of Nonadjacent Sampling 

Sites

Sampling sites within the study area but not adjacent 

to the Appalachian Trail were evaluated for inclusion in this 

inventory to increase the amount of water-quality data used to 

describe the water resources of the Appalachian Trail. Physical attributes of adjacent catchments were compared with all 

other first- and second-order catchments in the study area. 

Through this analysis, it was determined that stream elevation, 

the percentage of the drainage area classified as developed 

land, and the percentage of the drainage area classified as 

agricultural land were the most important criteria to determine 

if nonadjacent sampling sites were similar to the Appalachian 

Trail environment. 

The maximum stream elevation was used as the elevation variable for site selection rather than the maximum 

topographic elevation of the catchment because it more 

closely relates to the elevation at which a headwater streams 

forms. Developed land was defined to include low- and highintensity residential, as well as commercial, industrial, and 
26 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

transportation land cover. Land cover characterized as agricultural included pasture and row crops. 

Stream-elevation and land-cover data from the adjacent 

catchments were aggregated by hydrologic subregion. The 

number of adjacent catchments varies by subregion and is 

related to topography and to the proportion of the Appalachian 

Trail within the subregion. Summary statistics of elevation and 

land-cover information from adjacent catchments within each 

subregion were used to develop criteria for the selection of 

nonadjacent sampling sites by subregion. Hydrologic subregions were selected for the aggregation of adjacent catchment 

attributes because they provided reasonable and informative 

geographic divisions of major landscapes within the study 

area. The 21 subregions that intersect the Appalachian Trail 

are shown in figure 9. 

Nonadjacent sampling sites within the study area were 

selected for inclusion in the water-quality analysis if the following subregion criteria were met: (1) the stream elevation 

was equal to or greater than the lowest stream elevation of an 

adjacent catchment within the same subregion; (2) the percentage of agricultural land in the drainage area of the catchment 

did not exceed the 75th percentile for adjacent catchments 

within the same subregion; and (3) the percentage of developed land in the drainage area of the catchment did not exceed 

the 75th percentile for adjacent catchments within the same 

subregion (table 4). 

The thresholds for each of the criteria differ among the 

subregions and reflect the geographic variations in topography and land cover along the Appalachian Trail. The highest 

stream elevations were in the northern and southern subregions of the Appalachian Trail (table 4), while the lowest 

stream elevations were in subregions that coincide with the 

Hudson River Basin: the Upper Hudson, and the Lower 

Hudson–Long Island subregions (table 4). The thresholds 

for the percentage of developed land in the drainage area for 

all subregions were all less than 3 percent (table 4). In other 

words, nonadjacent sampling sites were never selected with 

developed land cover of 3 percent or greater in the drainage 

area. The threshold for the percentage of developed land in 

the drainage area was 0 for the 6 most southern subregions. 

Therefore, nonadjacent catchments could be selected in these 

subregions only if they contained no developed land cover. 

The subregions with the highest thresholds for the percentage 

of agricultural land cover were the Delaware (17.2 percent), 

the Susquehanna (26.8 percent), and the Potomac (27.7 percent) (table 4). Consequently in these subregions, nonadjacent 

sampling sites which had modest amounts of agricultural land 

cover in the drainage area were included in this inventory. 

The minimum stream-elevation thresholds in these subregions 

were useful in limiting the number of sampling sites retained 

with modest amounts of agricultural land cover.

Selected Sites and Data Aggregation

The final dataset for use in this project consisted of 

1,817 stream-sampling sites in 831 different catchments that 

represent approximately 450 different first- and second-order 

streams. Some catchments contained multiple sampling sites 

and some streams were represented by multiple catchments. 

There were 946 adjacent sampling sites and 871 nonadjacent 

sampling sites in the final dataset. Specific areas that contain 

numerous selected sites include the White Mountain National 

Forest in New Hampshire (fig. 13A), the Delaware Water Gap 

National Recreation Area in Pennsylvania and New Jersey 

(fig. 13B), the Shenandoah National Park in Virginia 

(fig. 13C), and the Great Smoky Mountains National Park in 

Tennessee and North Carolina (fig. 13D). Some areas had relatively few selected sampling sites with available water-quality 

data, with the most notable data gaps in Maine (fig. 12A). 

Only seven sampling sites in the State of Maine met the project criteria and were retained for analysis. Central Vermont, 

western Massachusetts, and Georgia also had few sampling 

sites retained for water-quality analysis (figs. 13A–B, D).

In addition to spatial disparities in the number of sites, 

the number of times each site was sampled and the constituents analyzed for each sample also were highly variable. The 

number of times a selected site was sampled ranged from one 

to more than a thousand. The most frequently sampled sites 

were primarily in the Shenandoah National Park. Approximately 58 percent of the sites used in this study were sampled 

at least five times. Thirty-eight percent of the sampling sites 

used in this study were sampled only once.

To mitigate a potential bias resulting from disparities in 

the spatial locations of sampling sites and in the frequencies 

of sampling, the data were aggregated in four steps: (1) data 

were aggregated by sampling site and date to determine a 

daily median value for each constituent; (2) daily median 

values were aggregated by sampling site and year to determine 

an annual median value for each constituent (for example, if 

300 daily median values of pH were recorded at a sampling 

site in one year, the median of these 300 pH values was 

determined as the annual median value for that year); (3)

annual median data were aggregated by site, thus reducing the 

data to one median annual value for each constituent at that 

site for the entire sampling period in years; and (4) data were 

aggregated by National Hydrography Dataset Plus (NHDPlus) 

catchments to a single median value for each constituent in 

each catchment. Sampling sites in the same catchment are on 

the same stream segment (fig. 10). The number of sampling 

sites within a catchment ranged from 1 to 55; however, 542 

of the 831 catchments contained only one sampling site. The 

resulting values (hereafter referred to as catchment values 

or concentrations) for each constituent were used to assess 

water quality along the Appalachian Trail and are available in 

addition to ancillary data in the catchment-data worksheet of 

appendix 1.
Methods of Analysis 27

Figure 11. Index map showing areas covered by figures 12 and 13.

80° 75° 70°

45°

40°

35°

0 50 100 MILES

0 100 200 KILOMETERS

VIRGINIA

NORTH CAROLINA

GEORGIA

TENNESSEE

WEST VIRGINIA

PENNSYLVANIA

NEW YORK

MAINE

NEW HAMPSHIRE

DELAWARE

NEW JERSEY

MASSACHUSETTS

CONNECTICUT

VERMONT

MARYLAND

RHODE ISLAND

EXPLANATION

Appalachian National Scenic Trail

Study-area boundary

State boundary

A

B

C

D

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Equal-Area Conic projection, NAD 1983

Base physical-map background is from U.S. National Park Service

Natural Earth physical map, available online from ESRI (2009)

Atlantic Ocean

Lake Ontario

Lake Erie

Lake 

Huron

Saint Lawrence River
28 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 12. First- and second-order catchments from the National Hydrography Dataset Plus (NHDPlus) that are adjacent 

to the Appalachian National Scenic Trail and were used to characterize physical attributes of the trail environment from 

A, Maine to Vermont, B, Massachusetts to Maryland, C, Maryland to Virginia, and D, Virginia to Georgia.

72° 70°

46°

44°

CANADA

UNITED STATES

0 30 60 MILES

0 50 100 KILOMETERS

EXPLANATION

Appalachian National Scenic Trail

Adjacent catchments

Study-area boundary

State boundary

MAINE

NEW HAMPSHIRE

VERMONT

MASSACHUSETTS

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data 

Albers Conic projection, NAD 1983

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

A
Methods of Analysis 29

Figure 12. —Continued

76° 74°

42°

40°

EXPLANATION

Appalachian National Scenic Trail

Adjacent catchments

Study-area boundary

State boundary

0 30 60 MILES

0 50 100 KILOMETERS

MASSACHUSETTS

CONNECTICUT

NEW YORK

PENNSYLVANIA

NEW 

JERSEY

MARYLAND

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

B
30 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

80° 78°

40°

38°

0 30 60 MILES

0 50 100 KILOMETERS

PENNSYLVANIA

WEST VIRGINIA

VIRGINIA

NORTH CAROLINA

MARYLAND

EXPLANATION

Appalachian National Scenic Trail

Adjacent catchments

Study-area boundary

State boundary

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

C

Figure 12. —Continued
Methods of Analysis 31

Figure 12. —Continued

84° 82°

38°

36°

0 30 60 MILES

0 50 100 KILOMETERS

TENNESSEE

KENTUCKY

VIRGINIA

NORTH CAROLINA

WEST VIRGINIA

SOUTH CAROLINA

GEORGIA

EXPLANATION

Appalachian National Scenic Trail

Adjacent catchments

Study-area boundary

State boundary

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

D
32 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 13. The spatial distribution of and the number of sampling sites in National Hydrography Dataset Plus (NHDPlus) 

catchments used in the level 1 inventory of first- and second-order streams along the Appalachian National Scenic Trail, 

A, Maine to Vermont, B, Massachusetts to Maryland, C, Maryland to Virginia, and D, Virginia to Georgia.

CANADA

UNITED STATES

72° 70°

46°

44°

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

MAINE

NEW HAMPSHIRE

VERMONT

MASSACHUSETTS

0 30 60 MILES

0 50 100 KILOMETERS

EXPLANATION

Selected catchments White Mountain National Forest

Number of sampling sites

1 to 2

3 to 5

6 to 55 Appalachian National 

Scenic Trail

Study-area boundary

State boundary

A
Methods of Analysis 33

Figure 13. —Continued

76° 74°

42°

40°

NEW YORK

PENNSYLVANIA

NEW 

JERSEY

MARYLAND

MASSACHUSETTS

CONNECTICUT

0 30 60 MILES

0 50 100 KILOMETERS

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

EXPLANATION

Delaware Water Gap 

National Recreation Area 

Selected catchments

Number of sampling sites

1 to 2

3 to 5

6 to 55 Appalachian National 

Scenic Trail

Study-area boundary

State boundary

B
34 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 13. —Continued

80° 78°

40°

38°

PENNSYLVANIA

WEST VIRGINIA

VIRGINIA

NORTH CAROLINA

MARYLAND

0 30 60 MILES

0 50 100 KILOMETERS

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

Shenandoah National Park

EXPLANATION

Selected catchments

Number of sampling sites

1 to 2

3 to 5

6 to 55 Appalachian National 

Scenic Trail

Study-area boundary

State boundary

C
Methods of Analysis 35

Figure 13. —Continued

84° 82°

38°

36°

TENNESSEE

KENTUCKY

VIRGINIA

NORTH CAROLINA

WEST VIRGINIA

SOUTH CAROLINA

GEORGIA

0 30 60 MILES

0 50 100 KILOMETERS

Catchment boundaries from National Hydrography Dataset Plus

 (U.S. Environmental Protection Agency, 2006a)

Physical-map background from the National Park Service

 Natural Earth physical map, available online from ESRI (2009)

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data 

Albers Conic projection, NAD 1983

Great Smoky Mountains

National Park

EXPLANATION

Selected catchments

Number of sampling sites

1 to 2

3 to 5

6 to 55 Appalachian National 

Scenic Trail

Study-area boundary

State boundary

D
36 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Statistical Methods

Selected data compiled for this study were statistically 

analyzed to characterize the water quality along the length of 

the Appalachian Trail using Version 9.3 of SAS (SAS Institute, 

2008). Summary statistics were computed by robust Regression on Order Statistics which uses a probability plot of the 

logarithms of the data to account for datasets that include 

multiple detection limits (Helsel and Cohn, 1988; Helsel, 

2005). In the robust Regression on Order Statistics method 

of analysis, detected values were used when available, while 

estimations were used for the censored portions of the distribution. In the combined dataset, each constituent had two to 

eight different detection limits, likely due to differences in 

laboratory analysis methods. Results less than the maximum 

detection limit for each constituent were considered estimated 

(Helsel, 2005). Dashed lines represent estimated values in box 

plots while estimated values in tables were reported by using 

italicized text. 

Water-quality data were grouped by ecosections and by 

major geologic units, and the Kruskal-Wallis statistical test 

was used to determine if there were statistical differences in 

water-quality data within these groupings. If a significant difference was found, Tukey’s multiple-comparison test was used 

to determine which group differed significantly (Helsel and 

Hirsch, 1992). Results from the Tukey’s multiple-comparison 

tests are shown by use of letters on the figures in this report; 

groups having the same letter underneath them are not significantly different. Groups that contained fewer than five values 

are shown as boxplots but were not compared statistically. A 

Spearman rank correlation (rho) test was used to determine 

the strength of association between two variables and to 

identify environmental attributes that might have influenced 

water quality along and near the Appalachian Trail. Physical 

attributes (elevation, slope, and size of the drainage area) and 

land-cover, soils, temperature, and precipitation data were 

tested to determine the extent to which each variable is correlated with water-quality data. The level of significance for 

all tests was set at 0.05. Significant rho values less than 0.4 are 

generally not discussed in this report because the correlations 

were considered weak.

Table 4. Threshold values, by subregion, of selected physical attributes used to screen nonadjacent sampling sites for 

inclusion in the water-quality summary of selected sampling sites along the Appalachian National Scenic Trail.

[Subregions are listed in approximate order from north to south; ft, feet]

Subregion

(hydrologic unit name)

Hydrologic 

unit code

Number of 

adjacent 

catchments

 Minimum stream 

elevation

(ft)

75th percentile of 

developed land cover 

(percent)

75th percentile of 

agricultural land cover

(percent)

Penobscot 0102 182 492 0 0.04

Kennebec 0103 73 487 0.03 0.10

Androscoggin 0104 74 1,015 0.01 0.05

Saco 0106 10 1,243 0.18 0.06

Merrimack 0107 36 1,012 0.04 0.37

Connecticut 0108 152 374 0.39 5.68

Richelieu 0201 41 658 0.71 5.92

Upper Hudson 0202 142 227 2.98 13.3

Connecticut Coastal 0110 136 347 1.25 10.8

Lower Hudson–Long Island 0203 52 0 1.47 0.83

Delaware 0204 141 291 0.71 17.2

Susquehanna 0205 129 332 0.12 26.8

Potomac 0207 199 220 0.65 27.7

Lower Chesapeake 0208 247 652 0.01 3.63

Chowan–Roanoke 0301 69 1,199 0.23 5.25

Kanawha 0505 147 1,895 0 15.8

Upper Tennessee 0601 597 1,318 0 1.06

Middle Tennessee–Hiwassee 0602 66 2,279 0 0.10

Ogeechee–Savannah 0306 26 2,728 0 0

Apalachicola 0313 37 2,323 0 0.12

Alabama 0315 9 1,904 0 0
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 37

Characterization of Selected Field 

Properties, Major-Ion Chemistry, Acid 

Neutralizing Capacity, and Nutrients

Water-quality data from the selected sampling sites 

were aggregated, summarized, and used to describe the basic 

character of and variations in the water quality along the 

Appalachian Trail. Concentrations and relative proportions 

of solutes in surface waters are primarily determined by 

the types of sediments and bedrock underlying the surface 

waters, residence time, atmospheric deposition, and climate. 

These environmental attributes vary over the length of the 

Appalachian Trail, and water chemistry also varies as a 

reflection of these changes. Nine of the 17 USFS ecosections 

had sufficient sampling sites with relevant water-quality 

data and were used for describing variations in water quality 

along the Appalachian Trail. The nine ecosections were the 

White Mountains, Vermont–New Hampshire Upland, Green–

Taconic–Berkshire Mountains, Lower New England, Hudson 

Valley, Northern Glaciated Allegheny Plateau, Northern Ridge 

and Valley, Blue Ridge Mountains, and Allegheny Mountains 

ecosections (fig. 7). Water-quality data from the White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 

ecosections typically demonstrated similar chemical 

concentrations that were markedly lower than concentrations 

measured in samples collected from the other ecosections. 

Differences in selected physical attributes among ecosections may help to indicate factors that influence variations in 

water quality along the Appalachian Trail. Physical attributes 

of the catchments that contained selected sampling sites are 

summarized by ecosection in table 5. The highest median 

elevations were in the southern (Allegheny Mountains and 

Blue Ridge Mountains, 2,495 and 2,474 ft respectively) and 

the northern (White Mountains and Green–Taconic–

Berkshire Mountains, 2,064 and 1,394 ft respectively) ecosections (table 5). Median slope values were greatest (steepest 

slopes) in the ecosections with the highest elevations, including the Allegheny Mountains, White Mountains, and Blue 

Ridge Mountains ecosections (table 5). The median percentage of developed land in drainage areas of catchments in the 

Lower New England ecosection was the highest (0.53 percent) 

(table 5). The Northern Ridge and Valley, Hudson Valley, 

Vermont–New Hampshire Upland, and Green–Taconic–

Berkshire Mountains ecosections contained the highest median 

percentages of agricultural land in the drainage areas of catchments (7.47, 4.09, 3.92, and 2.98, respectively) (table 5).

Field Properties

Temperature affects the life cycles and activity of aquatic 

organisms and the rates and equilibriums of biogeochemical 

reactions (Allen, 1995). Aggregated surface-water catchment 

temperature data for the 69 year period between March 1939 

and November 2008 ranged from 2.6 to 25.2oC (table 6). Most 

temperature values (56.7 percent) were less than 12oC, which 

may be indicative of cool headwater streams. Water temperatures greater than 20oC, which is generally considered an in 

stream upper limit for the protection of aquatic health, were 

recorded in 170 catchments (U.S. Environmental Protection 

Agency, 2006b). These warm temperatures were primarily 

observed between the months of July and September and were 

measured in all regions along the Appalachian Trail (including catchments with elevations greater than 2,500 ft). Water 

temperatures were related to season, elevation, and latitude. 

Catchments in the northern section of the Appalachian Trail 

generally had the coolest water temperatures in all seasons, 

whereas catchments in the central and southern sections of the 

Appalachian Trail generally had the warmest water temperatures in all seasons (table 7).

Dissolved oxygen is important in maintaining healthy 

stream biota because oxygen is necessary for the survival 

of many aquatic organisms, and is affected by many factors 

including ambient temperatures, atmospheric pressures, and 

ionic or biological activity. Catchment concentrations of dissolved oxygen ranged from 3.8 to 12.9 mg/L, with a median 

value of 9.5 mg/L (table 6). Five catchments had concentrations of dissolved oxygen less than 6 mg/L, which is generally 

considered the lower limit for the protection of aquatic health 

(U.S. Environmental Protection Agency, 2006b). Concentrations of dissolved oxygen appeared to be related to temporal 

variations, such as seasonal differences (table 7).

The pH of a water body is a measure of the Hydrogen 

ion (H+) concentration. pH helps to characterize the acid-base 

status of the water and has relevance to many water chemistry measures. Natural waters generally have pH values in the 

range of 6.5 to 8.5 (Hem, 1992). Catchment pH values ranged 

from 4.0 to 8.9 with a median value of 6.7 (table 6), with 

approximately 38 percent of the catchments (302) having pH 

values less than 6, pH values of 6, are generally considered an 

instream lower limit for the protection of aquatic health (U.S. 

Environmental Protection Agency, 2006b).

Statistical similarities and differences in median catchment pH values among the nine ecosections are shown in 

figure 14A. Median pH values from the White Mountain ecosection are the lowest and statistically unique among the other 

eight ecosections (median pH = 6.1) (fig. 14A, table 8). The 

Vermont–New Hampshire Upland, Green–Taconic–Berkshire 

Mountains, Lower New England, and Hudson Valley ecosections have the highest median catchment pH values of 7.1 to 

7.4 (fig. 14A, table 8).

Specific conductance is a measure of the ability of water 

to conduct an electric current and is related to the concentration of dissolved solids (Hem, 1992) and is reported as 

microsiemens per centimeter (μS/cm). Median catchment 

specific conductance values ranged from 4.0 to 761 μS/cm 

with a median value of 23.8 μS/cm (table 6). Approximately 

75 percent of the catchments had specific conductance values 

less than 50.0 μS/cm (table 6).

The White Mountains, Green–Taconic–Berkshire 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 
38 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Table 5. Summary statistics of selected physical attributes, by U.S. Forest Service ecological sections 

(ecosections), from catchments that contain selected sampling sites along the Appalachian National Scenic Trail.

[ft, feet]

Ecological section Number of 

catchments Minimum Median Maximum

Elevation (ft)

White Mountains 82 712 2,064 3,950

Vermont–New Hampshire Upland 25 430 971 1,985

Green–Taconic–Berkshire Mountains 71 689 1,394 2,818

Lower New England 36 381 833 1,490

Hudson Valley 30 302 722 1,332

Northern Glaciated Allegheny Plateau 13 548 873 1,158

Northern Ridge and Valley 57 417 804 1,703

Blue Ridge Mountains 369 522 2,474 5,351

Allegheny Mountains 88 955 2,495 4,091

Slope

White Mountains 82 0.00 0.06 0.20

Vermont–New Hampshire Upland 22 0.00 0.03 0.13

Green–Taconic–Berkshire Mountains 81 0.00 0.03 0.11

Lower New England 37 0.00 0.02 0.08

Hudson Valley 20 0.00 0.02 0.09

Northern Glaciated Allegheny Plateau 14 0.01 0.03 0.12

Northern Ridge and Valley 45 0.00 0.01 0.08

Blue Ridge Mountains 330 0.01 0.07 0.35

Allegheny Mountains 88 0.01 0.05 0.19

Percentage of developed land cover

White Mountains 82 0.00 0.00 1.08

Vermont–New Hampshire Upland 22 0.00 0.13 6.45

Green–Taconic–Berkshire Mountains 81 0.00 0.38 20.0

Lower New England 37 0.00 0.53 15.1

Hudson Valley 20 0.00 0.41 27.2

Northern Glaciated Allegheny Plateau 14 0.00 0.03 0.41

Northern Ridge and Valley 45 0.00 0.05 23.6

Blue Ridge Mountains 330 0.00 0.00 10.0

Allegheny Mountains 88 0.00 0.00 3.08

Percentage of agricultural land cover

White Mountains 82 0.00 0.01 5.40

Vermont–New Hampshire Upland 22 0.08 3.92 35.5

Green–Taconic–Berkshire Mountains 81 0.00 2.98 24.0

Lower New England 37 0.00 0.64 17.0

Hudson Valley 20 0.16 4.09 25.3

Northern Glaciated Allegheny Plateau 14 0.05 0.17 3.98

Northern Ridge and Valley 45 0.00 7.47 67.0

Blue Ridge Mountains 330 0.00 0.19 41.1

Allegheny Mountains 88 0.00 0.24 17.1
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 39

ecosections had the lowest median specific conductance 

values, which ranged from 17.7 to 25.8 μS/cm. The median 

specific conductance value from the Blue Ridge Mountains 

ecosection was the lowest when compared to the other 

ecosections. In contrast, the Vermont–New Hampshire Upland, 

Lower New England, Hudson Valley, Northern Glaciated 

Allegheny Plateau, and the Northern Ridge and Valley 

ecosections had higher median specific conductance values, 

which ranged from 41.0 to 108.1 μS/cm (fig. 14B, table 8). 

Major Ions

Major ions summarized in this report are common 

constituents dissolved in most natural waters and include 

bicarbonate, calcium, chloride, fluoride, magnesium, nitrate, 

potassium, silica, sodium, and sulfate (table 6). Median 

catchment concentrations of cations (calcium, magnesium, 

sodium, and potassium) were less than 1.5 mg/L and 

ranged from 0.47 to 1.46 mg/L (table 6). Median catchment 

concentrations of anions (bicarbonate, chloride, fluoride, 

nitrate, and sulfate) ranged more widely than those of cations; 

all medians were less than 10 mg/L and ranged from less than 

0.08 to 9.64 mg/L (table 6). 

Major-ion concentrations were compiled to develop water 

types. Water types can be an efficient way to describe variations in bulk water chemistry and also can be useful in identifying waters that have been contaminated from road salt or 

deposition. Water types were calculated based on the percentage of milliequivalents of the major ions present within each 

sample. In most samples compiled for this study, no one cation 

composed more than 50 percent of the total cations. Sulfate 

was the most frequently detected predominant anion. Consequently, calcium-magnesium mixed, sulfate was the most 

frequently determined water type. In the Lower New England 

and Hudson Valley ecosections however, calcium-bicarbonate 

was the most frequently calculated water type. 

Table 6. Summary statistics of concentrations of selected water-quality constituents from catchments that contain selected 

sampling sites along the Appalachian National Scenic Trail.

[°C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μeq/L, microequivalents per liter; <, less than, 

italic text indicates estimated values]

Property or constituent

(reporting units)

Number of 

catchments

Minimum 

value

25th 

percentile

Median 

value Mean value 75th percentile

Maximum 

value

Field properties

Water temperature (°C) 531 2.6 10.0 12.5 12.9 15.9 25.2

Dissolved oxygen (mg/L) 336 3.8 8.8 9.5 9.5 10.2 12.9

pH (standard units) 790 4.0 6.2 6.7 6.6 7.1 8.9

Specific conductance (μS/cm) 700 4.0 15.4 23.8 43.7 42.7 761

Acid neutralizing capacity (μeq/L) 629 -11.3 38.6 98.7 293 279 4,400

Major ions

Bicarbonate (mg/L) 163 0.26 3.55 9.64 22.9 24.9 262.0

Calcium (mg/L) 585 0.19 0.83 1.46 3.36 2.92 81.2

Chloride (mg/L) 656 0.20 0.53 0.78 2.76 1.85 150.0

Fluoride (mg/L) 105 < 0.08 < 0.08 < 0.08 0.10 0.10 1.7

Magnesium (mg/L) 625 0.10 0.34 0.64 2.18 1.43 52.0

Potassium (mg/L) 563 0.01 0.34 0.47 0.63 0.77 5.8

Silica (mg/L as SiO2) 399 0.25 0.60 1.18 9.76 4.99 207.7

Sodium (mg/L) 573 0.21 0.65 1.01 1.94 1.70 84.0

Sulfate (mg/L) 573 0.29 2.07 3.41 5.08 5.50 138.5

Nutrients

Ammonia (mg/L as N) 283 < 0.01 < 0.01 0.016 0.050 0.038 4.00

Nitrate (mg/L as N) 365 < 0.008 0.045 0.143 0.301 0.356 4.52

Total nitrogen (mg/L as N) 153 < 0.05 0.193 0.350 0.485 0.567 7.10

Total phosphorus (mg/L as P) 215 < 0.004 0.009 0.018 0.052 0.034 4.20
40 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Median concentrations of calcium, magnesium, and 

sodium (cations) from the Hudson Valley and Lower New 

England ecosections are among the highest compared to 

the other ecosections (figs. 14D–G) (table 8). One notable 

exception is catchment concentrations of magnesium in the 

Vermont–New Hampshire Upland and Green–Taconic–

Berkshire Mountains ecosections of 8.30 and 5.75 mg/L, 

respectively. Median catchment concentrations of calcium, 

magnesium, and sodium in the White Mountains, Blue Ridge 

Mountains, and Allegheny Mountains are among the lowest 

compared to the other ecosections (figs. 14D–F) (table 8). 

The White Mountains ecosection also had the lowest median 

catchment concentration of potassium and was statistically 

similar only to the Northern Glaciated Allegheny Plateau 

ecosection (fig. 14G). 

Catchment concentrations of common anions were 

similar to those of cations—generally lowest in the White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 

(figs. 14H–J, table 8). Catchment concentrations of sulfate 

in these three ecosections were lower than in the other 

six ecosections and statistically unique in the Blue Ridge 

Mountain ecosection (fig. 14H). Catchment concentrations 

of chloride in these three ecosections also were lower than in 

the other six ecosections and statistically unique in the White 

Mountains ecosection (fig. 14I). Catchment concentrations 

of chloride and sulfate in the Hudson Valley and Lower New 

England ecosections are generally higher than in the other 

ecosections (figs. 14H–I, table 8). Catchment concentrations 

of nitrate were generally lower than concentrations of sulfate 

and chloride, and the medians for five of the nine ecosections 

were estimated (fig. 14J, table 8). Catchment concentrations 

of nitrate were highest in the Northern Ridge and Valley, 

Green–Taconic–Berkshire Mountains, and Vermont–New 

Hampshire Upland ecosections: 0.416, 0.330 and 0.261 mg/L, 

respectively (fig. 14J, table 8). 

Overall, major ion concentrations are lower in the White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains 

ecosections and higher concentrations in the Lower New 

England and Hudson Valley ecosections. The Vermont–

New Hampshire Upland, Green–Taconic–Berkshire 

Mountains, Northern Glaciated Allegheny Plateau, and 

Northern Ridge and Valley ecosections represent the 

transition zones along the Appalachian Trail between the 

regions of highest and lowest elevation (table 5). The 

catchment concentrations of most major ions in these four 

transitional ecosections are generally lower than or similar 

to catchment concentrations from the Hudson Valley and 

Lower New England ecosections and greater than catchment 

concentrations from the White Mountains, Blue Ridge 

Mountains, and Allegheny Mountains ecosections. 

Table 7. Water temperature and dissolved oxygen concentrations by U.S. Forest Service ecological sections 

(ecosections) and by season from selected sampling sites along the Appalachian National Scenic Trail.

[°C, degrees Celsius; --, insufficient data (fewer than 5 reported values); mg/L, milligrams per liter]

Ecological section January to March April to June July to September October to December

Water temperature (°C)

White Mountains 0.5 7.8 13.3 3.9

Vermont–New Hampshire Upland 0.0 10.0 15.6 4.0

Green–Taconic–Berkshire Mountains 1.0 12.0 16.0 5.6

Lower New England 1.0 13.0 18.0 7.0

Hudson Valley 4.1 14.0 17.9 9.5

Northern Glaciated Allegheny Plateau -- 14.3 19.2 --

Northern Ridge and Valley 4.6 12.0 17.0 8.8

Blue Ridge Mountains 5.0 12.1 18.0 9.5

Allegheny Mountains 4.0 10.3 17.0 9.0

Dissolved oxygen (mg/L)

White Mountains -- 10.4 9.4 12.2

Vermont–New Hampshire Upland 13.6 10.7 8.9 12.3

Green–Taconic–Berkshire Mountains 14.0 10.0 9.2 11.5

Lower New England 11.1 9.2 8.0 9.8

Hudson Valley 13.4 10.0 8.7 11.4

Northern Glaciated Allegheny Plateau -- -- -- --

Northern Ridge and Valley 12.4 10.4 8.8 11.0

Blue Ridge Mountains 11.9 9.9 8.0 8.4

Allegheny Mountains 11.3 10.0 10.0 10.1
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 41

Table 8. Summary statistics of selected water-quality constituents by U.S. Forest Service ecological sections (ecosections) from 

catchments that contain selected sampling sites in headwater streams along the Appalachian National Scenic Trail.—Continued

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; μeq/L, microequivalents per liter; mg/L, milligrams per liter; <, less than; italic text indicates 

estimated values]

Ecological section Number of 

catchments Minimum 25th percentile Median 75th percentile Maximum

pH

White Mountains 84 4.6 5.6 6.1 6.3 7.3

Vermont–New Hampshire Upland 24 4.0 6.9 7.4 7.6 8.4

Green–Taconic–Berkshire Mountains 82 4.6 6.5 7.2 7.6 8.2

Lower New England 39 5.9 6.8 7.1 7.3 8.3

Hudson Valley 29 5.7 6.9 7.4 7.6 8.9

Northern Glaciated Allegheny Plateau 17 5.6 6.7 6.9 7.1 7.8

Northern Ridge and Valley 66 4.5 6.3 6.6 7.0 7.7

Blue Ridge Mountains 353 4.3 6.3 6.7 6.9 8.4

Allegheny Mountains 96 4.9 5.8 6.6 7.0 8.0

Specific conductance (μS/cm)

White Mountains 67 13.0 21.8 25.8 30.0 84.8

Vermont–New Hampshire Upland 19 27.0 51.0 84.0 118 351

Green–Taconic–Berkshire Mountains 28 18.0 21.8 27.3 32.0 109

Lower New England 36 39.0 55.5 94.4 144 761

Hudson Valley 28 30.0 47.0 108.1 168 421

Northern Glaciated Allegheny Plateau 16 25.0 46.3 64.8 84.3 124

Northern Ridge and Valley 59 13.7 31.3 41.0 67.0 532

Blue Ridge Mountains 352 4.0 13.1 17.7 27.9 263

Allegheny Mountains 95 7.9 13.2 20.5 37.0 421

Acid neutralizing capacity (μeq/L)

White Mountains 30 0 23 45 71.0 215

Vermont–New Hampshire Upland 20 0 424 820 1,086 2,680

Green–Taconic–Berkshire Mountains 81 0 140 350 762 3,984

Lower New England 33 84 200 394 960 2,390

Hudson Valley 20 14.2 120 575 901 3,710

Northern Glaciated Allegheny Plateau 12 36.8 135 169 210 352

Northern Ridge and Valley 38 8.35 93.8 164 300 4,400

Blue Ridge Mountains 306 -8.85 31.6 62.4 137 2,280

Allegheny Mountains 85 -11.3 6.8 66.9 204 2,900

Calcium (mg/L)

White Mountains 76 0.69 1.08 1.71 2.30 3.59

Vermont–New Hampshire Upland 7 2.10 2.30 3.50 22.0 47.0

Green–Taconic–Berkshire Mountains 18 1.35 1.54 2.48 3.45 13.7

Lower New England 28 3.63 4.75 8.08 16.1 39.0

Hudson Valley 18 1.88 4.40 8.47 17.9 49.0

Northern Glaciated Allegheny Plateau 11 2.11 3.07 5.14 5.66 8.04

Northern Ridge and Valley 35 0.19 2.24 3.46 7.50 81.2

Blue Ridge Mountains 313 0.21 0.71 1.06 1.82 27.5

Allegheny Mountains 79 0.19 0.66 1.28 3.42 35.4
42 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Table 8. Summary statistics of selected water-quality constituents by U.S. Forest Service ecological sections (ecosections) from 

catchments that contain selected sampling sites in headwater streams along the Appalachian National Scenic Trail.—Continued

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; μeq/L, microequivalents per liter; mg/L, milligrams per liter; <, less than; italic text indicates 

estimated values]

Ecological section Number of 

catchments Minimum 25th percentile Median 75th percentile Maximum

Magnesium (mg/L)

White Mountains 63 0.12 0.26 0.35 0.47 0.92

Vermont–New Hampshire Upland 13 0.48 0.94 8.30 13.0 26.0

Green–Taconic–Berkshire Mountains 65 0.28 1.26 5.75 12.0 52.0

Lower New England 28 1.00 1.58 2.68 6.88 15.0

Hudson Valley 18 0.87 1.61 2.50 3.22 17.0

Northern Glaciated Allegheny Plateau 11 0.69 0.95 1.06 1.26 1.71

Northern Ridge and Valley 36 0.10 0.86 1.43 2.43 15.7

Blue Ridge Mountains 313 0.12 0.28 0.49 0.83 8.65

Allegheny Mountains 78 0.16 0.35 0.53 0.80 29.9

Sodium (mg/L)

White Mountains 64 0.36 0.72 0.97 1.19 3.25

Vermont–New Hampshire Upland 6 1.42 1.65 1.96 4.70 8.00

Green–Taconic–Berkshire Mountains 35 0.21 0.78 1.32 2.56 16.6

Lower New England 24 1.50 2.05 3.00 6.38 84.0

Hudson Valley 19 0.75 1.49 3.90 8.40 22.6

Northern Glaciated Allegheny Plateau 12 0.76 2.05 5.28 7.82 19.0

Northern Ridge and Valley 31 0.51 1.07 2.17 3.20 21.4

Blue Ridge Mountains 307 0.32 0.71 0.99 1.55 20.7

Allegheny Mountains 75 0.22 0.31 0.37 0.60 18.5

Sulfate (mg/L)

White Mountains 53 2.07 3.32 4.00 4.61 7.63

Vermont–New Hampshire Upland 7 5.00 5.50 8.00 10.50 13.0

Green–Taconic–Berkshire Mountains 32 3.53 5.68 6.97 8.13 15.4

Lower New England 27 5.50 9.10 10.8 14.0 25.0

Hudson Valley 19 7.43 9.75 11.2 16.0 111.0

Northern Glaciated Allegheny Plateau 12 4.06 6.03 6.71 7.72 12.0

Northern Ridge and Valley 40 1.15 4.94 6.59 10.9 79.0

Blue Ridge Mountains 305 0.29 1.44 2.39 3.43 24.0

Allegheny Mountains 78 0.66 2.40 3.10 4.73 138.5

Chloride (mg/L)

White Mountains 74 0.24 0.37 0.48 0.60 18.8

Vermont–New Hampshire Upland 21 0.20 0.75 2.07 5.15 16.0

Green–Taconic–Berkshire Mountains 71 0.20 0.56 1.75 3.90 20.6

Lower New England 34 0.40 2.43 4.83 12.0 150.0

Hudson Valley 19 0.87 1.60 3.26 12.6 41.1

Northern Glaciated Allegheny Plateau 12 0.57 1.19 8.88 11.3 31.1

Northern Ridge and Valley 35 0.84 1.50 2.50 5.30 52.8

Blue Ridge Mountains 313 0.32 0.54 0.75 0.95 14.2

Allegheny Mountains 77 0.43 0.55 0.65 0.77 48.6
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 43

Table 8. Summary statistics of selected water-quality constituents by U.S. Forest Service ecological sections (ecosections) from 

catchments that contain selected sampling sites in headwater streams along the Appalachian National Scenic Trail.—Continued

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; μeq/L, microequivalents per liter; mg/L, milligrams per liter; <, less than; italic text indicates 

estimated values]

Ecological section Number of 

catchments Minimum 25th percentile Median 75th percentile Maximum

Nitrate (mg/L as N)

White Mountains 6 0.026 0.030 0.069 0.110 0.560

Vermont–New Hampshire Upland 6 0.023 0.148 0.261 0.430 1.42

Green–Taconic–Berkshire Mountains 15 0.021 0.255 0.330 0.625 0.840

Lower New England 28 0.021 0.058 0.129 0.399 2.00

Hudson Valley 16 0.009 0.022 0.118 0.261 0.928

Northern Glaciated Allegheny Plateau 12 0.019 0.037 0.100 0.310 0.960

Northern Ridge and Valley 37 0.014 0.150 0.416 0.576 4.36

Blue Ridge Mountains 210 < 0.008 0.038 0.127 0.343 4.52

Allegheny Mountains 35 < 0.008 0.015 0.063 0.149 1.85

Ammonia (mg/L as N)

White Mountains 52 < 0.01 0.010 0.023 0.053 0.175

Vermont–New Hampshire Upland 12 < 0.01 0.013 0.033 0.058 0.120

Green–Taconic–Berkshire Mountains 10 0.015 0.022 0.065 0.088 4.00

Lower New England 21 0.012 0.020 0.035 0.168 0.550

Hudson Valley 11 0.011 0.014 0.024 0.038 0.142

Northern Glaciated Allegheny Plateau 6 0.014 0.028 0.031 0.060 0.061

Northern Ridge and Valley 23 0.014 0.018 0.027 0.060 0.210

Blue Ridge Mountains 136 < 0.01 < 0.01 0.010 0.016 0.750

Allegheny Mountains 12 < 0.01 < 0.01 0.015 0.020 0.030

Total nitrogen (mg/L as N)

White Mountains 34 0.059 0.315 0.458 0.650 1.38

Vermont–New Hampshire Upland 4 0.420 0.450 0.500 0.570 0.620

Green–Taconic–Berkshire Mountains 12 0.185 0.367 0.413 0.810 0.990

Lower New England 6 0.240 0.290 0.398 0.590 2.30

Hudson Valley 6 0.320 0.380 0.460 0.500 0.604

Northern Glaciated Allegheny Plateau 11 0.064 0.140 0.355 0.485 0.545

Northern Ridge and Valley 22 0.100 0.330 0.530 0.710 7.10

Blue Ridge Mountains 45 0.054 0.124 0.216 0.338 1.91

Allegheny Mountains 11 0.053 0.065 0.119 0.193 0.343

Total phosphorus (mg/L as P)

White Mountains 13 0.005 0.009 0.010 0.010 0.010

Vermont–New Hampshire Upland 12 < 0.004 0.007 0.008 0.009 0.053

Green–Taconic–Berkshire Mountains 15 < 0.004 < 0.004 0.005 0.009 0.033

Lower New England 13 0.010 0.018 0.020 0.025 0.047

Hudson Valley 11 < 0.004 0.011 0.024 0.030 4.20

Northern Glaciated Allegheny Plateau 13 0.006 0.017 0.035 0.044 0.210

Northern Ridge and Valley 22 0.004 0.011 0.027 0.033 0.113

Blue Ridge Mountains 60 < 0.004 0.009 0.018 0.040 0.200

Allegheny Mountains 11 < 0.004 0.004 0.013 0.020 0.038
44 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 14. Comparisons of concentrations of A, pH, B, specific conductance, C, acid neutralizing capacity, D, calcium, 

E, magnesium, F, sodium, G, potassium, H, sulfate, I, chloride, J, nitrate, K, ammonia, L, total nitrogen, and M, total phosphorus, 

by U.S. Forest Service ecological sections (ecosections), from catchments that contain selected first- and second-order streams

along the Appalachian National Scenic Trail. Ecosections are displayed left to right in approximate north to south order.

0.5

5

50

H. Sulfate

(53)

(78)

(305)

(40)

(12)

(19)

(27)

(32) (7)

A B B B B B B C A

0.1

1

10

 G. Potassium

A BC BC BC BC AB BC B BC

(64)

(75) (304)

(30)

(11)

(18)

(21)

(35)

(5)

1

10

100

1,000 B. Specific conductance

(67)

(95)

(352)

(59)

(16)

(28)

(36)

(28)

(19)

AE BF ED BF BF BDF BD C AC

4

5

6

7

8

9

A. pH

(84)

(96)

(353)

(66) (17)

(29)

(39)

(82) (24)

A B B B B BC C C C

1

10

100

1,000

C. Acid neutralizing capacity

(30)

(38)

(12)

(20) (81) (33) (20)

(85)

(306)

A BC BC B BC BCD BC AD AD

5,000

D. Calcium

0.1

1

10

100

(76)

(18) (28)

(18)

(7)

(79)

(313)

(35)

(11)

ABC ABC ABC B BC BC BC D ACD

0.1

1

10

100

E. Magnesium

(63)

(28)

(78)

(313)

(36)

(11)

(18)

(13) (65)

A B B B B B B C C

0.1

1

10

100

 F. Sodium

(64)

(31)

(12) (19)

(24)

(35)

(6)

(75)

(307)

AC BC ABC B B B BC AC D

Concentration, in microequivalents 

per liter 

Specific conductance, in

microsiemens per centimeter pH, in standard units

Concentration, in milligrams 

per liter 

Concentration, in milligrams 

per liter

Concentration, in milligrams 

per liter 

Concentration, in milligrams 

per liter

Concentration, in milligrams 

per liter 

negative 

value*
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 45

Figure 14. —Continued

0.01

0.1

1

M. Total phosphorus

0.001

(13)

(22)

(13)

(11)

(13)

(15)

(12)

(11)

(60)

AB B AB CD AC C CD C ABCD

0.01

0.1

1

K. Ammonia

0.001

5

(52)

(6)

(11)

(21)

(10)

(12)

(12) (136)

(23)

AC AC A A AC AC AC B BC

0.1

1

0.01

L. Total nitrogen

5

(34)

(22)

(11) (6)

(6)

(12)

(4)

(45)

(11)

AC ABCD AC ACD ACD ABCD AC BCD BD

AC

I. Chloride

0.1

1

10

100

(74)

(313)

(35)

(12) (19)

(34)

(71) (21)

(77)

A BD D B B BD B C C

J. Nitrate

0.01

0.1

1

10

0.001

(6) (210)

(37)

(12)

(16)

(28) (15)

(6)

(35)

ABC ABC AB ABC ABC ABC AB AC AC

(12)

Allegheny Mountains

Blue Ridge Mountains

Northern Ridge and Valley

Northern Glaciated Allegheny Plateau

Hudson Valley

Lower New England

Green-Taconic-Berkshire Mountains

Vermont-New Hampshire Upland

White Mountains

Statistical group from nonparametric Tukey’s 

multiple-comparison test (groups with the same 

letter are not significantly different)

Tenth percentile of acid neutralizing capacity

for the Allegheny Mountains ecological section 

was equal to -5.6.

Concentration, in milligrams per liter Concentration, in milligrams per liter Concentration, in milligrams per liter

Concentration, in milligrams per liter Concentration, in milligrams per liter

EXPLANATION

Number of catchments

90th percentile

75th percentile

50th percentile (median)

25th percentile

10th percentile

Estimated, less than maximum detection limit

(multiple detection limits within data)

*
46 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Acid Neutralizing Capacity

Acid neutralizing capacity (ANC) is the capacity of a 

solution, including solutes plus particulates in an unfiltered 

water sample, to react with and neutralize acid (Rounds, 

2006). ANC values, measured in microequivalents per liter 

(μeq/L) help to characterize the acid-base chemistry of water 

and indicate a net strong base in solution if ANC is positive 

or a net strong acid if the ANC value is negative. Higher ANC 

values indicate greater ability to resist acidic inputs from 

sources such as acid deposition. Catchment values for ANC 

ranged from -11.3 to 4,400 μeq/L, with a median ANC value 

for the entire Appalachian Trail of 98.7 μeq/L (table 6). 

There were distinct differences in catchment ANC values 

among the ecosections (fig. 14C). As with pH, the median 

ANC value for all catchments in the White Mountains ecosection was the lowest of all the ecosections, with a median 

value of 45.0 μeq/L (table 8). Median catchment ANC values 

from the Blue Ridge Mountains and the Allegheny Mountains 

were statistically similar and among the lowest: 62.4 and 

66.9 μeq/L, respectively (fig. 14C, table 8). Catchments in the 

Vermont–New Hampshire Upland ecosection had the highest median ANC value (820 μeq/L) (table 8). The catchments 

from the Green–Taconic–Berkshire Mountains, Lower New 

England, and Hudson Valley ecosections also had relatively 

high median ANC values (350, 394, and 575 μeq/L, respectively) (table 8). The three ecosections (White Mountains, 

Blue Ridge Mountains, and Allegheny Mountains) that had the 

lowest catchment ANC values also had the lowest catchment 

concentrations of most major ions (figs. 14D–J) (table 8).

For comparison purposes, catchment ANC values were 

divided into three categories: ANC values less than zero were 

defined as acidic, ANC values between 0 and 50 μeq/L were 

classified as sensitive, and ANC values greater than 50 μeq/L 

were classified as insensitive (Kahl and Scott, 1988; Driscoll 

and others, 2001; Sullivan and others, 2007). Classification as 

sensitive and insensitive generally refers to the extent that the 

stream is susceptible to becoming acidic either seasonally or 

through event-driven episodic acidification. The percentages 

of catchments that had ANC values classified as acidic, sensitive, or insensitive are shown in table 9.

The ecosections with the most dilute waters—

White Mountains, Blue Ridge Mountains, and Allegheny 

Mountains—had the highest percentages of catchments 

classified as acidic or sensitive compared to all other 

ecosections (table 9). The Allegheny Mountains had the 

highest percentage of catchments classified as acidic 

(17.6 percent) while 1.6 of the catchments in the Blue Ridge 

Mountains ecosection were classified as acidic (table 9). 

The White Mountains ecosection had the highest percentage 

of catchments classified as sensitive (56.7) (table 9). The 

White Mountains ecosection contained no catchments that 

were classified as acidic; however, this may be the result 

of the titration methods most commonly used to determine 

ANC values in this ecosection. Most of the ANC data from 

the Blue Ridge and Allegheny Mountains ecosections were 

determined by use of Gran’s method and therefore are useful 

in fully characterizing the ANC of these dilute waters. Few 

of the ANC data from the White Mountains ecosection were 

determined by use of Gran’s method, and therefore low ANC 

values may be truncated or otherwise not fully determined. 

Previous investigations in the northeastern United States 

have shown that a substantial number of lakes are chronically 

acidic (Kahl and Scott, 1988; Charles and Christy, 2001). 

This information indicates that surface waters in the White 

Mountains ecosection are likely to be classified as acidic. 

The ANC data compiled for this inventory may under 

represent the extent of regions near or along the Appalachian 

Trail where noncarbonate alkalinity is a substantial contributor 

to ANC and where the ANC of streamwaters could be 

classified as acidic. 

Surface waters that have ANC low enough to be classified as acidic or sensitive are prone to seasonal and (or) event 

driven periods where the water quality is detrimental to the 

health of aquatic and terrestrial ecosystems. For most forested 

headwater streams, ANC is generally lower during higher 

streamflow (Rice and Bricker, 1995; Driscoll and others, 2001; 

Lawrence and others, 2004). Changes in streamflow can initiate significant changes in the water chemistry through dilution 

and (or) inputs of ions from deposition. Research on lakes 

and streams near the Appalachian Trail has helped scientists 

determine the processes that govern seasonal or event driven 

episodic acidification. Literature on investigations conducted 

Table 9. Comparison among U.S. Forest Service ecological 

sections (ecosections) of the percentages of catchments with 

acid neutralizing capacity classified as acidic (ANC less than or 

equal to 0 μeq/L), sensitive (ANC greater than 0 and less than 

50 μeq/L), or insensitive (ANC equal to or greater than 50 μeq/L). 

[μeq/L, microequivalents per liter]

Ecological section

Number 

of catchments

Percentage of catchments

Acidic Sensitive

Insensitive

White Mountains 30 0 56.7 43.3

Vermont–New Hampshire 

Upland

20 0 10 90

Green–Taconic–Berkshire 

Mountains

81 0 9.9 90.1

Lower New England 33 0 0 100

Hudson Valley 20 0 15 85

Northern Glaciated 

Allegheny Plateau

12 0 8.3 91.6

Northern Ridge and Valley 38 0 13.2 86.8

Blue Ridge Mountains 306 1.6 38.2 60.1

Allegheny Mountains 85 17.6 29.4 52.9
Characterization of Selected Field Properties, Major-Ion Chemistry, Acid Neutralizing Capacity, and Nutrients 47

in the Northeast, which includes the White Mountains ecosection, conclude that base-cation dilution is commonly the most 

important contributor to loss in ANC, coupled with increases 

of nitrate and dissolved organic carbon (Charles and Christie, 

1991; Wigington and others, 1996). In contrast, literature from 

studies conducted in the southern Appalachian Mountains, 

which includes the Blue Ridge Mountains and Allegheny 

Mountains ecosections, demonstrates that increases in sulfate, 

dissolved organic carbon, nitrate, and organic acids are more 

important than base-cation dilution in generating episodic 

acidification (Cook and others, 1994; Hyer and others, 1995; 

Deyton and others, 2009). Although streams in the White 

Mountains, Blue Ridge Mountains, and Allegheny Mountains ecosections are of similarly low ionic strength and are 

vulnerable to episodic acidification, the processes in the three 

ecosections that cause episodic acidification are distinctly 

different. Regional variations in watershed characteristics that 

influence the throughput and fluxes of ions—such as lithology, 

soil properties, and vegetation—likely play an important role 

in describing why the processes of episodic acidification are 

different between the ecosection in the north and ecosections 

in the south. 

Nutrients

Nutrients (ammonia, nitrate, total nitrogen, and total 

phosphorus) in surface water are essential to aquatic life but 

need to be in appropriate concentrations. Excessively high 

concentrations of nitrogen can be toxic to fish and harmful 

to humans. High concentrations of phosphorus can produce 

an overgrowth of algae, which can degrade aquatic habitats. 

Source of excess nutrients are commonly associated with 

developed and agricultural land uses including urban runoff, pesticide use, effluent, and atmospheric deposition. In 

undeveloped areas, atmospheric deposition and the weathering of rocks and soils are typically the largest contributors 

(Dubrovsky and others, 2010). In first- and second-order 

streams along the Appalachian Trail, concentrations of nutrients are typically not high enough to be harmful to aquatic life. 

Concentrations of nutrients in streams along some regions of 

the Appalachian Trail may be evaluated through comparisons 

to estimated background concentrations and to regional nutrient criteria. 

Catchment concentrations of ammonia were the lowest among the three nitrogen species with an overall median 

concentration of 0.016 mg/L (table 6). The highest median 

concentrations of ammonia were in catchments in the Green–

Taconic–Berkshire Mountains ecosection (0.065 mg/L) 

(fig. 14K, table 8). Concentrations of total nitrogen were the 

highest among the three nitrogen species (table 6). Median 

concentrations of total nitrogen were similar along most of the 

Appalachian Trail and ranged from 0.355 to 0.530 mg/L 

for most ecosections (fig. 14L, table 8). The Blue Ridge 

Mountains and Allegheny Mountains ecosections were the 

exception; these two ecosections had lower median 

concentrations of total nitrogen (0.216 and 0.119 mg/L, 

respectively; table 8). 

Catchment concentrations of total phosphorus ranged 

from less than 0.004 to 4.20 mg/L, with an estimated median 

catchment concentration of 0.018 mg/L (table 6). Median 

catchment concentrations of phosphorus are higher in the 

middle and southern ecosections than in the northern ecosections (fig. 14M, table 8). The region of the Appalachian Trail 

where concentrations of total phosphorus appeared to change 

is near the southernmost extent of the most recent glacial 

advance between the Green–Taconic–Berkshire Mountains 

and the Lower New England ecosections. Median catchment 

concentrations of phosphorus may be higher in the nonglaciated regions of the Appalachian Trail because more abundant 

deposits of weathered sediments may provide a source of suspended sediment, which typically entrains and transports phosphorus in the streams. Comparative evaluation of the average 

percentages listed in the State Soil Geographic database of 

clay and sand in the soil of each ecosection showed that the 

middle and southern ecosections contain more clay-rich soil, 

while the northern ecosections contain more sandy soil.

Catchment concentrations of nutrients from selected 

sampling sites in headwater streams along the Appalachian 

Trail were compared to estimated national background 

concentrations (Dubrovsky and others, 2010) (table 10). 

Estimated national background concentrations were based on 

data from streams across the Nation in areas with minimal 

or no development and included sites in semiarid and arid 

regions (Dubrovsky and others, 2010). Overall catchment 

concentrations of ammonia, nitrate, total nitrogen, and total 

phosphorus were lower at sites along the Appalachian Trail 

Table 10. Comparison of median catchment concentrations 

of nutrients and the percentages of median concentrations 

greater than estimated national background concentrations from 

selected sampling sites along the Appalachian National Scenic 

Trail.

[mg/L, milligrams per liter; italic text indicates estimated values]

Constituent

Estimated 

national 

background 

concentrations 

(mg/L)1

Median 

catchment 

concentrations

(mg/L)

Percentage 

of catchment 

concentrations 

greater than 

estimated national 

background 

concentrations

Ammonia 0.025 0.016 35.3

Nitrate 0.24 0.143 36.9

Total nitrogen 0.58 0.35 23.5

Total phosphorus 0.034 0.018 25.1

1

 Estimates for national background concentrations are from Dubrovsky 

and others, 2010.
48 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

as compared to estimated national background concentrations 

(table 10). However, on a smaller scale, the Vermont–New 

Hampshire Upland, Green–Taconic–Berkshire Mountains, 

Northern Glaciated Allegheny Plateau, and the Northern Ridge 

and Valley ecosections had median catchment concentrations 

of ammonia that were higher than estimated national 

background concentrations (tables 8 and 10). Additionally, the 

Vermont–New Hampshire Upland, Green–Taconic–Berkshire 

Mountains, and the Northern Ridge and Valley ecosections had 

median catchment concentrations of nitrate that were higher 

than estimated national background concentrations (tables 8 

and 10).

The USEPA has developed recommended ecoregional criteria for total nitrogen and total phosphorus that are intended 

to approximate reference or background concentrations and 

serve as guidelines to protect against nutrient enrichment (U.S. 

Environmental Protection Agency, 2000; 2002b). The nutrient ecoregion criteria reflect the regional influences of natural 

variations in geology, land cover, and climate that affect background concentrations of nutrients. Most of the selected catchments in this study were in one of two nutrient ecoregions, 

the Nutrient-Poor Largely Glaciated Upper Midwest and 

Northeast (New York to Maine) and the Central and Eastern 

Forested Upland (New Jersey to Georgia). Catchment concentrations of total nitrogen and total phosphorus from headwater 

streams along the Appalachian Trail were compared to USEPA 

nutrient ecoregion criteria (table 11). Approximately 63.4 percent of catchment concentrations of total nitrogen in the Nutrient-Poor Largely Glaciated Upper Midwest and Northeast 

nutrient ecoregion were greater than the recommended USEPA 

nutrient criterion (table 11). Approximately 70.5 percent of the 

catchment concentrations of total phosphorus in the Central 

and Eastern Forested Upland nutrient ecoregion were greater 

than the recommended USEPA nutrient criterion (table 11). 

Sections of the Appalachian Trail pass through urban 

areas and are adjacent to agricultural land (table 5). Intermittent influences from the regions of the Appalachian Trail 

where the percentages of developed or agricultural land are 

moderate may be increasing the number of catchments that 

have concentrations of total nitrogen and total phosphorus greater than the USEPA’s nutrient ecoregion criteria. 

Dubrovsky and others (2010) compared simulated modeled 

estimations of background concentrations from Smith and others (2003) to the 14 USEPA nutrient ecoregion criteria. This 

comparison demonstrated that, for the Nutrient-Poor Largely 

Glaciated Upper Midwest and Northeast and the Central and 

Eastern Forested Upland nutrient ecoregions, the criteria 

would be difficult to meet even with only a small percentage of development. Overall concentration of total nitrogen 

and total phosphorus within the study area are lower than 

estimated national background concentrations but generally 

similar or higher than USEPA ecoregion nutrient criteria. 

Effects of Environmental Attributes on 

Water Quality

Variations in water quality along the Appalachian Trail 

were evaluated with respect to selected environmental attributes to determine how natural or anthropogenic factors may 

be influencing the water quality of the headwater streams 

along and near the Appalachian Trail. Physical attributes 

such as elevation, slope, precipitation, and temperature were 

explored for correlation with water-quality constituents. Generalized major geologic units were used to group water-quality 

data along the Appalachian Trail to determine geologic effects 

Table 11. Comparison, by nutrient ecoregion, of median catchment concentrations of total nitrogen and total phosphorus and 

the percentages of median catchment concentrations greater than U.S. Environmental Protection Agency’s nutrient criteria from 

selected sampling sites along the Appalachian National Scenic Trail.

[mg/L, milligrams per liter]

Nutrient Nutrient ecoregion

Nutrient 

criterion

(mg/L)

Number of 

catchments

Median 

catchment 

concentrations 

(mg/L)

Percentages of median catchment concentrations greater 

than nutrient criterion

Total nitrogen Nutrient-poor largely glaciated Upper 

Midwest and Northeast

0.38 71 0.42 63.4

Central and Eastern forested upland 0.31 80 0.28 45.0

Total phosphorus Nutrient-poor largely glaciated Upper 

Midwest and Northeast

0.01 82 0.01 51.4

Central and Eastern forested upland 0.01 95 0.02 70.5
Effects of Environmental Attributes on Water Quality 49

on water quality. Anthropogenic factors such as developed and 

agricultural land use in the drainage area of headwater streams 

and atmospheric deposition of sulfate and nitrate in the catchments of headwater streams were evaluated with respect to 

possible influence on water quality.

Elevation

Catchment pH, ANC, and concentrations of major ions 

were significantly correlated with elevation along the length 

of the entire Appalachian Trail (table 12) except in the Lower 

New England ecosection where pH and most concentrations 

of major ions were not correlated with elevation. As elevation increases, pH, ANC, and concentrations of major ions 

decrease. Likewise, most concentrations of nutrients also were 

negatively correlated with elevation, although rho values were 

substantially lower than those computed for pH, ANC, and 

concentrations of major ions (table 12). 

Elevation is not directly affecting streamwater chemistry but is more likely a proxy for the synergistic influences 

of environmental attributes that tend to be correlated with 

elevational gradients, such as geology, slope, drainage area, 

precipitation, temperature, and land cover (table 13). Generally, in the Eastern U.S. as elevation increases, drainage areas 

tend to become smaller and steeper, and geology at elevation tends to be increasingly resistant to weathering. The low 

residence times of small steep drainages coupled with relatively inert geology yield comparatively more dilute waters 

compared to surface waters at lower elevations. These types 

of high elevation landforms typically have little to no agricultural or developed land uses, and receive higher amounts 

of precipitation in cooler climates which also help to explain 

the inverse relation between water quality and elevation. The 

inverse correlation between elevation and streamwater chemistry also has been documented in local and regional investigations of areas along the Appalachian Trail (Cook and others, 

1994; Shubzda and others, 1995; Hornbeck and others, 2001; 

Rice and others, 2005; Likens and Buso, 2006; Sullivan and 

others, 2007; Robinson and others, 2008). The variation of 

temperature with latitude along the Appalachian Trail is likely 

reducing the strength of the relation typically found between 

elevation and temperature at smaller scales (table 13). Mean 

annual temperature was negatively correlated with elevation at 

the ecosection scale. 

Geology

Generalized major geologic units from Reed and Bush 

(2005) were used to group and evaluate differences in water 

quality. This geologic map was compiled to be used for 

national or regional assessments of geology and shows the 

age, distribution, and general character of the rocks (Reed and 

Bush, 2005). Ten major geologic units underlie the selected 

catchments and include rocks classified as sedimentary, 

gneissic, granitic, and volcanic (fig. 15). Most (over 

78 percent) of the study area is underlain by sedimentary 

rocks. Sedimentary rocks classified by Reed and Bush include 

rocks that have been metamorphosed to varying extents but 

still retain evidence of their depositional age and origin (Reed 

and Bush, 2005). The regions of metamorphism are shown by 

a pattern in figure 15. Approximately 13 percent of the study 

area is underlain by gneissic rocks, approximately 5 percent 

is underlain by granitic rocks, and 1.4 percent is underlain by 

volcanic rocks.

Table 12. Rho values from Spearman correlations of the 

elevations of catchments and the percentages of developed 

and agricultural land cover with concentrations of selected 

water-quality constituents in catchments that contained selected 

sampling sites along the Appalachian National Scenic Trail.

[All rho values are significant (p less than 0.05) from Spearman correlations]

Water-quality parameter 

or constituent Elevation Percentages of land cover

Developed Agricultural

pH -0.422 0.416 0.517

Acid neutralizing capacity -0.613 0.557 0.557

Calcium -0.564 0.522 0.455

Magnesium -0.675 0.576 0.603

Sodium -0.563 0.471 0.408

Sulfate -0.687 0.579 0.451

Chloride -0.691 0.555 0.565

Nitrate -0.110 0.307 0.266

Total nitrogen -0.312 0.423 0.241

Total phosphorus -0.286 0.173 0.305

Table 13. Rho values from Spearman correlations of elevation 

with selected environmental attributes of catchments that 

contain selected sampling sites along the Appalachian National 

Scenic Trail.

[Boldface indicates significant rho values (p less than 0.05) from Spearman 

correlations]

Environmental attributes Elevation

Slope 0.592

Mean annual precipitation 0.542

Mean annual temperature 0.046

Percentage of developed land cover -0.599

Percentage of agricultural land cover -0.568
50 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 15. Major geologic units within the study area. Major geologic units that did not underlie catchments from the 

selected first- and second-order streams within the study are grey.

80° 75° 70°

45°

40°

35°

Atlantic Ocean

Saint Lawrence River

Lake Ontario

Lake Erie

Lake 

Huron

Appalachian National 

Scenic Trail

Study-area boundary

State boundary

Geology

Proterozoic

Proterozoic and Lower Paleozoic 

Lower Paleozoic (Cambrian and Ordovician) 

Middle Paleozoic (Silurian, Devonian, and Mississippian) 

Upper Paleozoic (Pennsylvanian and Permian) 

Lower Paleozoic granites

Middle Paleozoic granites

Mesozoic granites

Proterozoic volcanic

Proterozoic gneiss

Other geologic units (not specified)

Sedimentary rock

Other metamorphic rock

Igneous rock

Overlay pattern represents areas of metamorphism

EXPLANATION

0 100 200 MILES 

0 150 300 KILOMETERS

State-line boundaries from U.S. Geological Survey 1:2,000,000-scale digital data

Albers Conic projection, NAD 1983

Physical-map background from National Park Service

Natural Earth physical map, available online from ESRI (2009)

Geologic units modified from Reed and Bush (2005)
Effects of Environmental Attributes on Water Quality 51

For evaluation of geology with respect to water quality, 

the major geologic units were combined into six rock types 

(sedimentary rocks, metasedimentary rocks, metasedimentary 

rocks that contain carbonate minerals, gneissic rocks, 

granitic rocks, and volcanic rocks). The six rock types used 

in analysis were created by aggregating similar rocks from 

different geologic ages. For example, the sedimentary rock 

group included the Late Proterozoic sedimentary rocks, Late 

Proterozoic and Lower Paleozoic sedimentary rocks, Lower 

Paleozoic (Cambrian and Ordovician) sedimentary rocks, 

Middle Paleozoic (Silurian, Devonian, and Mississippian) 

sedimentary rocks, and the Upper Paleozoic (Pennsylvanian 

and Permian) sedimentary rocks. The sedimentary group was 

then subdivided to reflect whether a catchment was in a region 

of metamorphism and whether the rocks were classified as 

containing carbonate minerals (King and Beikman, 1974) 

because these geologic attributes can have a strong influence 

on the water quality. Granitic major geologic units that 

were combined into the granitic group included the Lower 

Paleozoic, Middle Paleozoic, and the Mesozoic granitic rocks. 

Only one major geologic unit each was adequate for gneissic 

rocks (Middle Proterozoic gneiss) and volcanic rocks (Late 

Proterzoic volcanic rocks).

Catchment values of pH, specific conductance, and 

ANC were compared among the six geologic groups (fig. 16). 

Generally, sedimentary rocks and metasedimentary rocks had 

similar median catchment values for pH, specific conductance, 

and ANC (fig. 16). For the sedimentary rocks, the median 

pH was equal to 6.6, specific conductance was equal to 23.7, 

and ANC was equal to 88.7 μeq/L. Similarly, catchments in 

the metasedimentary rocks had a median pH of 6.5, median 

specific conductance of 20.3, and median ANC of 86.3 μeq/L. 

However, catchment values for pH and ANC were statistically higher in the metasedimentary rocks that were classified 

as containing carbonate minerals compared to the other two 

groups of sedimentary rocks (median pH of 7.3; median ANC 

value of 590 μeq/L). The median catchment values of pH 

in the gneissic and volcanic rocks were statistically similar 

to that of the metasedimentary rocks that contain carbonate 

minerals (6.8 and 7.1, respectively) (fig. 16). Additionally, the 

catchment values of ANC in the volcanic rocks were among 

the highest with a median value of 220 μeq/L (fig. 16). Catchment pH and ANC values from granitic rocks were the lowest 

compared to the other rock types (median pH value of 6.0; 

median ANC value of 57 μeq/L) (fig. 16).

The presence of carbonate minerals appears to be 

the more influential geologic attribute with respect to pH, 

specific conductance, and ANC in the headwaters along the 

Appalachian Trail. Catchments were classified as containing 

carbonate minerals through the use of a national geologic 

map by King and Beikman (1974), who compiled national 

geologic data at a finer scale than Reed and Bush (2005) 

(1:2,500,000 and 1:7,500,000 scales, respectively) and 

characterized discrete areas of the sedimentary rocks in 

the region of the Green–Taconic–Berkshire Mountains, 

Lower New England, and Hudson Valley ecosections as 

containing carbonate minerals. This may provide a geologic 

explanation for generally higher pH, specific conductance, 

ANC, concentrations of cations, and concentration of anions 

that are observed in these three ecosections relative to other 

ecosections (figs. 14A–J). 

In general, the coarse scale of the geologic data could not 

be related to the fine-scale spatial variations in water quality such as variations within ecosections. Sullivan and others 

(2007), however, produced a lithologic map (at a scale of 

approximately 1:500,000) based on aggregated geologic map 

units for the southern Appalachian Mountains and were able to 

identify lithologies that were more likely to be associated with 

low-ANC surface water. Sullivan and others (2007) demonstrated that streams in the southern Appalachian Mountains in 

or downgradient from drainage areas that are predominantly 

underlain by siliceous lithologies have a greater probability of 

low ANC. These findings are consistent with other studies that 

were conducted in and around the Shenandoah National Park 

in Virginia (Bricker and Rice, 1989; Rice and others, 2005). In 

addition, these findings demonstrate that, with relatively highresolution geologic information, significant relations can be 

determined between water quality and the underlying lithology 

at relatively fine scales.

Land Cover

The percentages of developed or agricultural land cover 

in the drainage areas of catchments selected for this inventory 

were generally low, although sections of the Appalachian Trail 

do pass through or near major urban areas or agricultural land 

(table 5). Along the entire Appalachian Trail, the percentages 

of developed and agricultural land were significantly and positively correlated with pH, ANC, concentrations of major ions, 

and concentrations of nitrate, total nitrogen, and total phosphorus (table 12). Within ecosections, these correlations were 

less significant. Insufficient spatial representation of a gradient 

of developed or agricultural land uses within ecosections may 

explain why these correlations were significant at the whole 

study-area scale of Appalachian Trail and not within ecosections. Many studies have demonstrated that land use influences 

stream quality. Siemion and Murdoch (2010) and Hickman 

and Fischer (2007) both reported that ANC and concentrations of most major ions and nutrients were positively correlated with agricultural land cover in the Delaware Water Gap 

National Recreation Area. The percentages of agricultural land 

cover in these two studies were generally higher than for the 

selected sampling sites in this project. (figs. 14B–J, table 8). 

Atmospheric Deposition

Previous studies of areas near the Appalachian Trail have 

demonstrated the negative effects of atmospheric deposition 

on water quality. Atmospheric-deposition data were compared to water-quality data to determine relations between 

these two datasets. The NADP publishes annual maps of 
52 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Figure 16. Comparison of concentrations, by major geologic groups, of A, pH, B, specific conductance, and C, acid 

neutralizing capacity from catchments that contained selected first- and second-order streams along the Appalachian 

National Scenic Trail.

DC

A. pH

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

Volcanic rocks

Granitic rocks

Gneissic rocks

Metasedimentary rocks that

contain carbonate minerals

Metasedimentary rocks

Sedimentary rocks

5

50

500

A A

AB A ADC AB ABC DC

B AB C B

A A B A AC AB

(22)

Geologic groups

(104)

(14)

(95)

(379)

(19)

(37)

(99)

(5)

(117)

(423)

(22)

(49)

(119)

(14)

(456) (130)

(17)

(16)

Microsiemens per centimeter (μS/cm) Standard units Concentrations, in microequivalents 

per liter (μeq/L)

EXPLANATON 

90th percentile

25th percentile

75th percentile

50th percentile (median)

10th percentile

Number of catchments

Statistical group from nonparametric 

Tukey’s multiple-comparison test 

(groups with the same letter are 

not significantly different)

Boxplots

C. Acid neutralizing capacity

B. Specific conductance

1

10

100

1,000

10,000
Effects of Environmental Attributes on Water Quality 53

precipitation-weighted mean concentrations of sulfate and 

nitrate in precipitation. The values are interpolated from measurements at specific sites (National Atmospheric Deposition 

Program, 1994a, b). Since most of the sulfate and nitrate data 

used in this project were collected in the mid-1990s, atmospheric sulfate and nitrate data from the NADP for 1994 were 

selected for comparison purposes. Atmospheric-deposition 

rates of sulfate and nitrate were computed by combining the 

NADP atmospheric-concentration data with high-resolution 

spatial estimates of precipitation rates for the same year 

(Latysh and Wetherbee, in press; PRISM Climatic Group, 

2006b). The resulting maps of sulfate and nitrate atmospheric 

deposition (in kilograms per hectare) are shown in figure 17. 

Mapped values were assigned to catchments in the study area, 

which enabled the comparison of atmospheric-deposition rates 

with other catchment attributes and with water-quality data. 

Atmospheric deposition was estimated by ecosection, including all first- and second-order catchments in the study area and 

not just the catchments with selected sampling sites.

Along the Appalachian Trail, atmospheric deposition is 

estimated to be high (greater than 20 kg/ha) at both the highest 

and lowest elevations. The spatially sustained estimates of 

high deposition (figs. 17 and 18) were broadest in the central 

portion of the Appalachian Trail, whereas estimates were highest for the highest elevations in the northern and southern sections of the Appalachian Trail. The Green–Taconic–Berkshire 

Mountains, Lower New England, Hudson Valley, Northern 

Glaciated Allegheny Plateau, and Northern Ridge and 

Valley ecosections have median deposition estimates greater 

than 24 kg/ha for sulfate and greater than 19 kg/ha for nitrate 

(figs. 18A–B). In the southern region of the Appalachian Trail 

(Allegheny Mountains and Blue Ridge Mountains ecosections), Great Smoky Mountains National Park has historically 

received high estimates of deposition. The Integrated Forest 

Study, which monitored forested sites across the U.S., Canada, 

and Norway to investigate the effects of acidic deposition 

on nutrient cycling in forest ecosystems, reported that the 

Noland Divide Watershed in the Great Smoky Mountains 

Figure 17. Maps of 1994 annual wet-deposition estimates for A, sulfate and B, nitrate for the eastern United States, including the 

study area. Deposition values were computed using methods from Laytsh and Wetherbee (in press) with atmospheric concentration 

data from the National Atmospheric Deposition Program National Trends Network (National Atmospheric Deposition Program, 1994 a, 

b) and precipitation from the PRISM climate group (PRISM Climate Group, 2006b).

State-line boundaries from U.S. Census Cartographic Boundaries

U.S. Geological Survey 1:5,000,000-scale digital data 

Albers Conic projection, NAD 1983

State-line boundaries from U.S. Census Cartographic Boundaries

U.S. Geological Survey digital 1:5,000,000-scale digital data

Albers Conic projection, NAD 1983

Colorpleth map generated from Latysh and

 Wetherbee (in press) using NADP and PRISM data

Colorpleth map generated from Latysh and

 Wetherbee (in press) using NADP and PRISM data

EXPLANATION

Nitrate deposition

(kg/ha) (kg/ha)

0 to 4

>4 to 6

>6 to 8

>8 to 10

>10 to 12

>13 to 14

>14 to 16

>16 to 18

>18 to 20

>20 to 22

>22 to 34

EXPLANATION

Sulfate deposition

0 to 3

>3 to 6

>6 to 9

>9 to 12

>12 to 15

>15 to 18

>18 to 21

>21 to 24

>24 to 27

>27 to 46

A. Sulfate B. Nitrate

Study-area boundary

State boundary

Study-area boundary

State boundary
54 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

National Park received the highest sulfate and nitrate deposition compared to the other Integrated Forest Study sampling 

sites (Shubzda and others, 1995). Generally higher elevations 

are more likely to receive high depositions, however for the 

five ecosections in the central region of the Appalachian Trail, 

climatic patterns and possibly sources of sulfate and nitrate, 

to some extent, outweigh the elevation-induced effects of precipitation on estimates of atmospheric deposition.

Catchment concentrations of sulfate in streamwater were 

statistically greater in the ecosections that received the highest 

atmospheric deposition estimates of sulfate (figs. 14H and 

18A). However, catchment concentrations of nitrate and total 

nitrogen in streamwater were not statistically greater in the 

ecosections that receive the highest atmospheric deposition of 

nitrate (figs. 14J and L). 

Previous studies have demonstrated a link between high 

concentrations of sulfate in precipitation and sulfate typically 

being the dominant anion in low-ionic strength waters 

(Charles and Christie, 1991; Likens and Bormann, 1995; 

Driscoll and others, 1998; Elliott and others, 2008). Sulfate 

was most frequently determined to be the predominant anion 

in waters in the Appalachian Trail study area except in the 

Lower New England and Hudson Valley ecosections, where 

bicarbonate was the most frequently calculated predominant 

anion. Although the central region of the Appalachian Trail 

received higher amounts of sulfate deposition, the areas 

along the Appalachian Trail with waters of lower ionic 

strength (White Mountains, Allegheny Mountains, Blue 

Ridge Mountains ecosections) might have been more strongly 

affected by sulfate deposition. 

Reductions in concentrations of sulfate and nitrate 

in atmospheric deposition related to the CAAA have been 

observed throughout the Midwest and Eastern United States, 

specifically in the central Appalachians (U.S. Environmental 

Protection Agency, 2010) that includes the Green–Taconic–

Berkshire Mountains, Lower New England, Hudson Valley, 

Northern Glaciated Allegheny Plateau, and Northern Ridge 

and Valley ecosections. Reductions in sulfate have been more 

significant than reductions in nitrogen—approximately 40 

and 20 percent, respectively (U.S. Environmental Protection 

Agency, 2010). The estimates of atmospheric deposition by 

ecosection shown in figures 17 and 18 were a reasonable 

fit for the data compiled for this inventory but may not 

represent a current estimate (2011) of concentrations in 

atmospheric deposition.

Figure 18. Wet-deposition estimates from 1994 of A, sulfate and B, nitrate by U.S. Forest Service ecological sections (ecosections) 

for all first and second order catchments in the study area. Deposition values were computed using methods from Laytsh and 

Wetherbee (in press) with atmospheric concentration data from the National Atmospheric Deposition Program National Trends 

Network (National Atmospheric Deposition Program, 1994a, b) and precipitation data are from the PRISM climate group (PRISM 

Climate Group, 2006b). Ecosections are shown left to right in approximate north-to-south order.

8

10

12

14

16

18

20

22

24

26

(4,522)

(6,567)

(13,947)

(4,286)

(939) (2,477)

(3,837)

(2,551)

(1,929) (4,522)

(6,567)

(13,947)

(939) (2,477)

(3,837)

(2,551)

(1,929)

(4,286)

10

12

14

16

18

20

22

24

26

28

30

32

34

EXPLANATION

Allegheny Mountains

Blue Ridge Mountains

Northern Ridge and Valley

Northern Glaciated Allegheny Plateau

Hudson Valley

Lower New England

Green-Taconic-Berkshire Mountains

Vermont-New Hampshire Upland

White Mountains

90th percentile

25th percentile

75th percentile

50th percentile (median)

10th percentile

(4,522) Number of catchments

Annual estimates of nitrate in deposition, 

in kilograms per hectare 

Annual estimates of sulfate in deposition, 

in kilograms per hectare

A. Sulfate B. Nitrate
Implications of Using Available Data and Considerations for Future Monitoring 55

Trends in concentrations of sulfate and nitrate in streams 

along the Appalachian Trail were not assessed. Regional 

investigations that have been completed near the Appalachian 

Trail reported that concentrations of sulfate and nitrate 

in surface water are decreasing in response to changes in 

atmospheric deposition (Driscoll and others, 1998; Driscoll 

and others, 2003; Stoddard and others, 2003; Kahl and 

others, 2004; Webb and others, 2004; Monteith and others, 

2007). The degree of response is likely to vary along the 

Appalachian Trail; however, surface waters with the lowest 

ANC and lowest pH were reported to have shown the largest 

and most rapid response (Stoddard and others, 2003; Kahl and 

others, 2004). In the eastern U.S., three processes have been 

identified that complicate the assessment of surface-water 

response to decreases in atmospheric deposition: increasing 

concentrations of chloride from road-salting practices that 

alter the acid-base chemistry of a watershed, increasing 

concentrations of dissolved organic carbon, and the retention 

of sulfate in watershed soils in nonglaciated areas (Rochelle 

and Church, 1987; Stoddard and others, 2003; Kahl and 

others, 2004; Webb and others, 2004; Monteith and others, 

2007; Rosfjord and others, 2007). These processes will likely 

play varying roles in assessments of trends in concentrations 

of sulfate and nitrate in headwater streams along the 

Appalachian Trail.

The more chemically dilute surface waters in the northern 

and southern regions of the Appalachian Trail than in the 

central region of the Appalachian Trail may be attributed to 

differences in most of the environmental attributes explored 

(elevation, geology, land use, and deposition). The central 

region of the Appalachian Trail (including the Lower New 

England, Hudson Valley, Northern Glaciated Allegheny 

Plateau, Northern Ridge and Valley, and to a lesser extent 

the Vermont–New Hampshire Upland and Green–Taconic–

Berkshire Mountains ecosections) generally had the highest 

catchment values of pH, ANC, and concentrations of major 

ions. In addition, the catchments in these ecosections also were 

the lowest in elevation and contained the highest percentages 

of developed and agricultural land cover. These three 

environmental attributes were demonstrated to be positively 

correlated with catchment pH, ANC, and concentrations of 

major ions. Portions of ecosections in the central region of the 

Appalachian Trail were associated with carbonate geologic 

units. The presence of carbonate minerals in the geology 

underlying a catchment could have substantial influence on 

pH, ANC, and major-ion chemistry. The central region of 

the Appalachian Trail also was shown to receive the highest 

estimated concentrations of sulfate and nitrate in atmospheric 

deposition. It is difficult to discern on the basis of the data 

compiled for this project whether the type of land cover, the 

lithology of the underlying geology, inputs of atmospheric 

deposition, or a combination of these factors is responsible for 

the distinctly different water quality in the central region of 

the Appalachian Trail compared to the northern and southern 

regions of the Appalachian Trail. 

Implications of Using Available 

Data and Considerations for Future 

Monitoring

The compilation of available water-quality data for this 

study was useful in identifying regions along the Appalachian 

Trail where water-quality data are lacking spatially and temporally. As was previously described, there is a notable lack 

of sampling sites that met this projects criteria in the state of 

Maine. The spatial density of available sampling sites along 

the border between Tennessee and North Carolina and north of 

Great Smoky Mountains National Park also was low, though 

not as low as in Maine. The spatial gaps were more profound 

when the data density for specific water-quality constituents 

was evaluated. 

In the 831 catchments where water-quality data was 

collected, field properties such as pH, specific conductance, 

temperature, and dissolved oxygen were the most commonly 

measured parameters. The next most frequently measured 

type of water-quality data was concentrations of major ions, 

including, calcium, chloride, magnesium, potassium, sodium, 

and sulfate. Of the four nutrients of interest, nitrate had the 

largest number of data values; however, very little nitrate data 

were available from areas along the Appalachian Trail north of 

Massachusetts. Ammonia was the most widely collected nutrient, followed by total phosphorus. Spatial coverage of total 

nitrogen data for the White Mountains of New Hampshire, the 

southern part of Pennsylvania, and the western mountains of 

Virginia were moderately good, but lacking for other regions 

of the Appalachian Trail. 

It is important to note a temporal-limitation of the data 

compiled for this inventory to represent current (2011) waterquality conditions along the Appalachian Trail. Specifically, 

spatial comparisons of concentrations of sulfate and nitrate 

may be biased because concentrations of sulfate and nitrate in 

streamwater have been reported to be declining in response 

to reductions in deposition related to the CAAA. Much of the 

data in the northern section region were from the 1980s and 

would be more representative of water quality influenced by 

deposition loads of that decade. Whereas, the collection dates 

of water-quality samples from the southern section (median 

year = 1997) reflect the inclusion of TIME/LTM stream sites, 

VTSSS sites, and Great Smoky Mountains National Park 

sites, at which water-quality data are being actively collected 

(2011). The comparatively lower concentrations of sulfate 

and nitrate in streamwater in the Blue Ridge Mountains and 

Allegheny Mountains ecosections may reflect the inclusion of 

more recent (post-2000) data that has responded to decreases 

in atmospheric deposition. 

Water-quality data were not evaluated within the context 

of hydrologic condition because of the lack of streamflow 

measurements available for many sites. Future monitoring 

programs for water quality along the Appalachian Trail should 

consider locating sampling sites within gaged watersheds, so 
56 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

that water-quality data can be related to streamflow. Assessments of trends in the water quality of streams over time are 

frequently done through a comparison of changes in loads or 

flow-adjusted concentrations. The calculation of load for a 

given parameter is dependent on both the concentration and 

streamflow at the time of sample collection. The calculation 

of relations between streamflow and water quality for streams 

along the Appalachian Trail would provide a useful tool to 

evaluate water-quality trends in this environment. Generally, streamgages are placed in larger watersheds; however, 

the Hubbard Brook and Coweeta LTER areas represent good 

examples of small watersheds that have generated useful timeseries chemical and hydrological data.

The data compiled for this inventory were generally 

either from the largest national databases of water-quality data 

(NWIS and STORET), federal agencies (for example, USEPA 

Wadeable Streams Assessment and National Stream Survey), 

or from well established programs (i.e. National Science 

Foundation LTER and the VTSSS). The inclusion of new 

water quality data in selected catchments and in catchments 

where data were not compiled for this inventory would 

improve the spatial and temporal resolution of available data 

from which to assess water resources. Continued integration 

of more recent data from the data sources used would be 

an efficient future effort in making the Appalachian Trail 

inventory of water-quality data more relevant for continued 

evaluation of basic water quality and in trend analysis. In 

addition, an effort to obtain and compile water-quality data 

from local citizen-based water-quality monitoring programs 

may be beneficial and facilitate a connection between local 

and regional scale water-quality issues. These smaller 

programs are typically initiated and focused on the intention 

of using scientific information to help locally preserve natural 

resources; this objective is common with aspects of the NPS 

mission. Collaborative arrangements to centralize waterquality data among agencies, programs, and researchers 

interested in the water resources of the Appalachian Trail 

region may serve to maintain the relevancy of the data 

compiled for this inventory. 

Summary

An inventory of water-quality data was conducted to 

provide an assessment of water quality in headwater (firstand second-order) streams along the Appalachian National 

Scenic Trail (Appalachian Trail). The Appalachian Trail is a 

cooperatively managed National Park along the Appalachian 

Mountains from Maine to Georgia. Available data on basic 

chemical quality were compiled from 14 different agencies or 

projects including the U.S. Geological Survey (USGS); the 

U.S. Environmental Protection Agency (USEPA); the National 

Park Service; the United States Forest Service; (USFS); 

the National Science Foundation, including the Long-Term 

Ecological Research Program; the Water Resources Research 

Center at the University of Massachusetts, Amherst; and the 

Department of Environmental Sciences at the University 

of Virginia. To maximize the amount of water-quality data 

available for use in this inventory and to provide a more robust 

assessment of the water quality of headwater streams along 

the Appalachian Trail, a method of sampling-site selection 

was developed based on proximity, hydrologic boundaries, 

and environmental settings. Hydrologic boundaries were 

used to define the watersheds draining the Appalachian Trail, 

and NHDPlus digital hydrologic data were used to define 

the catchment as the fundamental areal unit for location 

information for sampling sites.

The approach used for site selection in this study quantified selected physical attributes of catchments adjacent to the 

Appalachian Trail to build a criteria matrix by which sampling 

sites not adjacent to the Appalachian Trail could be compared 

and evaluated for inclusion. Stream elevation and the percentages of developed and agricultural land cover in the drainage 

areas of adjacent catchments were used to build the criteria. 

There were 1,817 sampling sites selected for water-quality 

characterization. These selected sites were either adjacent to 

the Appalachian Trail or in landscapes that are locally high in 

elevation and generally had little to no developed or agricultural land cover in the drainage area. 

Water-quality data from sampling sites were aggregated 

by catchments to reduce the spatial bias of intensively sampled 

sites and regions and at least one median water-quality value 

was computed for each of 831 catchments. The number of 

catchments for which a median value was calculated varies 

by water-quality parameter. Field properties were the most 

commonly measured, followed by concentrations of major 

ions and nutrients. Catchment concentrations of selected 

water-quality constituents were summarized overall and 

by USFS ecological sections (termed ecosections in this 

study). The pH of headwater streams from the Appalachian 

Trail study ranged from 4.0 to 8.9 with a median value 

of 6.7. Specific conductance values ranged from 4.0 to 

761 microsiemens per centimeter (μS/cm), with a median 

value of 23.8 μS/cm. Acid neutralizing capacity (ANC) ranged 

from -11.3 to 4,400 microequivalents per liter (μeq/L) with 

a median value of 98.7 μeq/L. Catchment concentrations of 

cations (calcium, magnesium, sodium, and potassium) were 

low with the median catchment concentration for each of 

the cations being less than 1.5 milligrams per liter (mg/L). 

Calcium had the highest median catchment concentration 

of all the cations (1.46 mg/L). Catchment concentrations of 

anions (sulfate, chloride, and nitrate) ranged more widely than 

those of cations. Sulfate had the highest median catchment 

concentration (3.41 mg/L), followed by chloride (0.78 mg/L). 

Analysis to characterize water types demonstrated that, for 

most regions of the Appalachian Trail, no specific cation was 

predominant. The Lower New England and Hudson Valley 

ecosections were the exceptions, where the predominant 

cation in most catchments was calcium. Sulfate was the most 

frequently detected anion except in the Lower New England 

and Hudson Valley ecosections where the predominant anion 
Summary 57

was bicarbonate. Similar to major ions, nutrient concentrations 

also were low (median catchment concentrations of total 

nitrogen and nitrate species were less than 0.4 mg/L, and the 

median catchment concentration of total phosphorus were less 

than 0.02 mg/L). 

Distinct spatial variations in pH, ANC, and major-ion 

chemistry were apparent along the length of the Appalachian 

Trail. The northern and southern regions of the Appalachian 

Trail (including the White Mountains, Blue Ridge Mountains, 

and Allegheny Mountains ecosections) had the lowest 

catchment pH values. The White Mountains ecosection was 

statistically unique and had the lowest median catchment pH 

value of all the ecosections (median catchment pH = 6.1). 

Catchment ANC and concentrations of most major ions also 

were statistically lower in the White Mountains, Blue Ridge 

Mountains, and Allegheny Mountains ecosections compared to 

the other ecosections. 

The ANC of waters from the White Mountains, Blue 

Ridge Mountains, and Allegheny Mountains ecosections were 

exceptionally low and included negative values. The White 

Mountains, Allegheny Mountains, and Blue Ridge Mountains 

ecosections contained the highest percentage of catchments 

that were classified as either acidic or sensitive. Low ANC 

waters are sensitive to seasonal or event-driven episodic 

acidification. When episodic acidification occurs in a stream, 

streamwater quality may become harmful to aquatic life.

Catchment concentrations of ammonia, nitrate, total 

nitrogen, and total phosphorus from selected headwater 

streams along the Appalachian Trail were generally lower than 

national estimated background concentrations determined by 

the USGS for surface waters. The Green–Taconic–Berkshire 

Mountains and the Northern Ridge and Valley ecosections 

were the exceptions. These ecosections had median catchment 

concentrations of ammonia more than two times greater than 

the estimated background concentrations. The Northern Ridge 

and Valley ecosection had median catchment concentrations of 

nitrate greater than the estimated national background concentrations (0.416 and 0.24 mg/L, respectively). 

Median catchment concentrations of total nitrogen and 

total phosphorus were compared to USEPA’s ecoregion nutrient criteria. Median concentrations of total nitrogen in approximately 63 percent of catchments in the Nutrient Poor Largely 

Glaciated Upper Midwest and Northeast were higher than 

the USEPA regional criterion. Approximately 71 percent of 

median concentrations of total phosphorus in the Central and 

Eastern Forested Upland nutrient ecoregion were higher than 

the USEPA regional criterion. Findings from Dubrovsky and 

others (2010) suggest that the USEPA criteria in some nutrient ecoregions may be difficult to meet with modest amounts 

of development or agriculture in the drainage area. Sections 

of the central region of the Appalachian Trail are adjacent to 

areas of development and agricultural land. These nonforested 

land cover types may be contributing to the percentages of 

catchments that have total nitrogen and total phosphorus concentrations greater than USEPA nutrient criteria.

Spatial variations in water-quality properties of surface 

waters along the Appalachian Trail were related to elevation, 

geology, land cover, and atmospheric deposition. Median pH, 

specific conductance, ANC, and concentrations of major ions 

(calcium, magnesium, sodium, sulfate, chloride, nitrate, total 

nitrogen, and total phosphorus) were all negatively correlated 

with elevation along the Appalachian Trail. For the Lower 

New England, Hudson Valley, Northern Glaciated Allegheny 

Plateau, and Northern Ridge and Valley ecosections, nitrate 

also was negatively correlated with elevation. Elevation, as 

such, most likely does not directly affect stream-water chemistry but is more likely a surrogate that represents the combined 

effects of environmental attributes that are themselves correlated with elevation, including geology, slope, drainage area, 

precipitation, temperature, and land cover. 

Approximately, 78 percent of the study area is underlain 

by sedimentary or metasedimetary rocks. Most of the remaining study area is underlain by gneissic, granitic, and volcanic 

rocks (13, 5, and 1.5 percent, respectively). Metasedimentary 

rocks were further subdivided to distinguish between metasedimentary rock and metasedimentary rocks that contain carbonate minerals. The presence of carbonate minerals appears to 

be the most influential geologic attribute with respect to pH, 

specific conductance, and ANC values. Catchments that were 

classified as being underlain by metasedimentary rocks that 

contained carbonate minerals had the highest values for pH, 

specific conductance, and ANC. The Green–Taconic–

Berkshire Mountains, Lower New England, and Hudson 

Valley ecosections, which contained the highest catchment pH, 

ANC, and concentrations of most major ions, are underlain, 

at least in some areas, by metasedimentary rocks that contain 

carbonate minerals. Catchment values of pH in the gneissic 

and volcanic rocks were statistically similar to the metasedimentary rocks with carbonate minerals, however, very little 

of the study area is underlain by these rock types. The 

granitic rocks occur primarily north of Vermont in the White 

Mountains ecosection. Catchments underlain by these granitic 

rocks contained among the lowest pH, specific conductance 

and ANC values.

The percentages of developed urban or agricultural land 

cover in the drainage areas of catchments was significantly 

and positively correlated with catchment pH, ANC, and concentration of most major ions (calcium, magnesium, sodium, 

sulfate, chloride, and nitrate). Nutrients were significantly, 

although weakly, correlated with the two land-cover variables. 

The regions along the Appalachian Trail that contained high 

percentages of developed and agricultural land cover in the 

drainage area were also underlain by major geologic units that 

may contain carbonate rocks. 

Atmospheric deposition of sulfate and nitrate as demonstrated by previous investigations may have lead to widespread deleterious effects on the water quality of headwater 

streams near the Appalachian Trail. Annual atmospheric deposition maps of sulfate and nitrate produced by the National 

Atmospheric Deposition Program and the USGS demonstrate 

that portions of the Appalachian Trail receive some of the 
58 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

highest concentrations of sulfate and nitrate in the eastern 

United States. The section of the Appalachian Trail that 

received the overall highest estimates of atmospheric deposition generally contained in the lowest elevations (Green–

Taconic–Berkshire Mountains, Lower New England, Hudson 

Valley, Northern Glaciated Allegheny Plateau, and Northern 

Ridge and Valley ecosections). Generally, there were higher 

catchment concentrations of sulfate in the ecosections that 

received the highest inputs of atmospheric deposition (Green–

Taconic–Berkshire Mountains, Lower New England, Hudson 

Valley, Northern Glaciated Allegheny Plateau, and Northern 

Ridge and Valley). However, these same ecosections also contained the highest concentrations of most major ions. Sulfate 

deposition in the ecosections that contain the waters 

of lowest ionic strength (White Mountains, Blue Ridge 

Mountains, and Allegheny Mountains ecosections) may have a 

more profound effect on the chemical character of the surface 

waters as shown by the predominance of the sulfate anion in 

surface waters in these ecosections. 

In general, the surface waters of the Appalachian Trail 

environment are dilute in constituents. Although this finding 

was not unexpected, the low ionic strength of Appalachian 

Trail surface waters may affect management and preservation 

strategies. These data also demonstrate that the waters of the 

central region of the Appalachian Trail, although still dilute, 

had statistically higher concentrations of most major ions and 

ANC than the northern and southern sections. Furthermore, 

the central section of the Appalachian Trail contained some 

of the highest percentages of developed and agricultural land 

uses and received the highest estimates of sulfate and nitrate 

from atmospheric deposition. It is difficult to tell from these 

data whether the water quality in the central section of the 

Appalachian Trail has been influenced more by the higher 

percentages of developed or agricultural land cover, higher 

inputs of atmospheric deposition, or the lithology of the 

underlying geology. 

Managing the water resources of the Appalachian Trail is 

a complex and challenging responsibility because the headwater streams are generally dilute and therefore sensitive to 

atmospheric deposition. As has been demonstrated by previous 

investigations of discrete sections of the Appalachian Trail and 

regions near the Appalachian Trail, the water resources of the 

Appalachian Trail have been altered by atmospheric deposition of sulfate and, to a lesser extent, nitrate. Furthermore, 

because of the intrinsic connection between headwaters and 

downstream areas, degradation of the headwaters along the 

Appalachian Trail most likely has affected the water quality 

of downstream resources. A specific set of sampling sites that 

are collocated with continuous flow record sites could be used 

to assess long-term trends in stream-water chemistry along the 

Appalachian Trail. The ability to assess and compare changes 

in streamflow-adjusted water-quality data would provide 

a clearer characterization of past and current water-quality 

conditions that would be helpful for resource managers in the 

management and protection of local catchments and water 

resources of the Appalachian Trail. The periodic inclusion of 

more recent data from data sources used in the Appalachian 

Trail water-quality inventory would be relatively straightforward and beneficial. Furthermore, an expanded effort to obtain 

data not compiled (such as water quality from localized citizen 

based monitoring programs) also would add value and maintain the relevancy of the effort of this inventory. A dynamic 

and timely database relevant to the Appalachian Trail study 

area water resources available to the NPS and to the consortium of researchers interested in understanding the impacts of 

climate change on water quality may facilitate more efficient 

collaboration to develop strategic ecological sound management practices based on scientific knowledge. 

Selected References

Acid Rain Monitoring Project, 2008, Water Resource Institute 

of Massachusetts, Amherst, Massachusetts accessed on 

February 10, 2010, at http://www.umass.edu/tei/wrrc/arm/

index.html.

Alexander, R.B., Boyer, E.W., Smith, R.A., Schwarz, G.E., 

and Moore, R.B., 2007, The role of headwater streams in 

downstream water quality: Journal of the American Water 

Resources Association, v. 43, no. 1, p. 41–59.

Allen, J.D., 1995, Stream ecology structure and function of 

running waters: London, Chapman & Hall, 388 p.

Baker, J.P., Van Sickle, J., Gagen, C.J., DeWalle, D.R., Sharpe, 

W.E., Carline, R.F., Baldigo, B.P., Murdoch, P.S., Bath, 

D.W., Kretser, W.A., Simonin, H.A., and Wigington, P.J., 

Jr., 1996, Episodic acidification of small streams in the 

northeastern United States—Effects on fish populations: 

Ecological Applications, v. 6, no. 2, p. 422–437.

Bailey, S.W., Horsley, S.B., and Long, R.P., 2005, Thirty 

years of change in forest soils of the Allegheny Plateau, 

Pennsylvania: Soil Science Society of American Journal, 

v. 69, p. 681–690.

Baldigo, B.P., and Murdoch, P.S., 1997, Effects of stream 

acidification and inorganic aluminum on mortality of brook 

trout (Salvelinus fontinalis) in the Catskill Mountains, New 

York: Canadian Journal of Fisheries and Aquatic Sciences, 

v. 54, p. 603–615.

Bricker, O.P., and Rice, K.R., 1989, Acidic deposition to 

streams: Environment Science and Technology, v. 23, no. 4, 

p. 379–385.

Cai, Meijun, Schwartz, J.S., Robinson, R.B., Moore, S.E., 

and Kulp, M.A., 2009, Long-term effects of acidic deposition on water quality in a high-elevation Great Smoky 

Mountains National Parks National Park watershed—Use of 

an ion input-output budget: Water Air Soil Pollution, 

doi: 10.1007/s11270–009–0187–5, 14 p.
References 59

Charles, D.F., and Christie, S., eds. 1991, Acid deposition and 

aquatic ecosystems: New York, New York, Springer-Verlag, 

747 p.

Childress, C.J.O., Foreman, W.T., Connor, B.F., and Maloney, 

T.J., 1999, New reporting procedures based on long-term 

method detection levels and some considerations for 

interpretations of water-quality data provided by the U.S. 

Geological Survey National Water Quality Laboratory: 

U.S. Geological Survey Open-File Report 99–193, 19 p.

Cook, R.B., Elwood, J.W., Turner, R.R., Bogle, M.A., 

Mulholland, P.J., and Palumbo, A.V., 1994, Acid-base 

chemistry of high-elevation streams in the Great Smoky 

Mountains National Parks: Water, Air, and Soil Pollution, 

v. 72, p. 331–356.

Cosby, B.J., Webb, J.R., Galloway, J.N., and Deviney, F.A., 

2006, Acidic deposition impacts on natural resources 

in Shenandoah National Park: National Park Service 

Technical Report NPS/NER/NRTR–2006/066, 35 p.

Coweeta Long Term Ecological Research, 2010, accessed 

February 14, 2010, at http://coweeta.uga.edu/pubcatalog.

Deyton, E.B., Schwartz, J.S., Robinson, R.B., Neff, K.J., 

Moore, S.E., and Kulp, M.A., 2009, Characterizing episodic 

stream acidity during stormflows in the Great Smoky 

Mountains National Park: Water Air and Soil Pollution, 

v. 196, p. 3–18.

Dieffenbach, F.W., 2011, Appalachian National Scenic Trail 

vital signs monitoring plan: Natural Resource Report NPS/

NETN/NRR 2011/389, National Park Service, Fort Collins, 

Colo., 127 p.

Driscoll, C.T., 1985, Aluminum in acidic surface waters—

Chemistry, transport, and effects: Environmental Health 

Perspectives, v. 63, p. 93–104.

Driscoll, C.T., Driscoll, K.M., Roy, K.M., and Mitchell, 

M.J., 2003, Chemical response of lakes in the Adirondack 

region of New York to declines in acidic deposition: 

Environmental Science and Technology, v. 37, 

p. 2036–2042.

Driscoll, C.T., Lawrence, G.B., Bulger, A.J., Butler, T.J., 

Cronan, C.S., Eagar, Christopher, Lambert, K.F., Likens, 

G.E., Stoddard, J.L., and Weathers, K.C., 2001, Acidic 

deposition in the northeastern United States—Sources 

and inputs, ecosystem effects, and management strategies: 

Bioscience, v. 51, no. 3, p. 180–198.

Driscoll, C.T., Lawrence, G.B., and Church, M.R., 1998, 

Recovery of surface waters in the northeastern U.S. from 

decreases in atmospheric deposition of sulfur: Water, Air, 

and Soil Pollution, v. 105, p. 319–329.

Dubrovsky, N.M., Burow, K.R., Clark, G.M., Gronberg, J.M., 

Hamilton, P.A., Hitt, K.J., Mueller, D.K., Munn, M.D., 

Nolan, B.T., Puckett, L.J., Rupert, M.G., Short, T.M., 

Spahr, N.E., Sprague, L.A., and Wilber, W.G., 2010, The 

quality of our Nation’s waters—Nutrients in the Nations 

streams and groundwater, 1992–2004: U.S. Geological 

Survey Circular 1350, 174 p., accessed August 28, 2010, at 

http://water.usgs.gov/nawqa/nutrients/pubs/circ1350/.

Dufour, C., and Crisfield, E., eds. 2008, The Appalachian 

Trail MEGA–Transect: Appalachian Trail Conservancy, 

31 p., accessed August 2010, at http://www.appalachiantrail.org/atf/cf/%7BD25B4747-42A3-4302-8D48-

EF35C0B0D9F1%7D/ATMEGATransectReport.pdf.

Elias, P.E., Burger, J.A., and Adams, M.B., 2009, Acid 

deposition effects on forest composition and growth on 

the Monongahela National Forest, West Virginia: Forest 

Ecology and Management, v. 258, p. 2175–2182.

Elliott, K.J., Vose, J.M., Knoepp, J.D., Johnson, D.W., Swank, 

W.T., and Jackson, William, 2008, Simulated effects of 

sulfur deposition on nutrient cycling in class 1 wilderness 

areas: Journal of Environmental Quality, v. 37, p. 1419–

1431.

ESRI, 2009, National Park Service Natural Earth physical 

map. 500 m per pixel, accessed September 2009, at 

http://www.esri.com/software/arcgis/arcgisonline/

standard-maps.html.

Fenneman, N.M., and Johnson, D.W., 1946, Physiographic 

divisions of the conterminous U.S.: Washington, D.C., 

U.S. Geological Survey Special Map, scale 1:7,000,000, 

accessed March 12, 2008, at http://water.usgs.gov/lookup/

getspatial?physio.

Freeman, M.C., Pringle, C.M., and Jackson, C.R., 2007, 

Hydrologic connectivity and the contribution of stream 

headwaters to ecological integrity at regional scales: 

Journal of American Water Resources Association, v. 43, 

no. 1, p. 5–14.

Gesch, D.B., 2007, The National Elevation Dataset, in

Maune, D., ed., Digital Elevation Model technologies and 

applications—The DEM Users Manual (2d ed.): Bethesda, 

Md., American Society for Photogrammetry and Remote 

Sensing, p. 99–118.

Gran, G., 1952, Determination of the equivalence point in 

potentiometric titrations—Part II, The Analyst, v. 77, 

p. 661–671.

Godfrey, P.J., 1988, Acid rain in Massachusetts: University of 

Massachusetts, Water Resources Research Center, publication no. 171, accessed August 17, 2010, at http://www.

umass.edu/tei/wrrc/WRRC2004/pdf/acid%20rain%20booklet.pdf.
60 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Helsel, D.R., 2005, Nondetects and data analysis—statistics 

for censored environmental data: New York, John Wiley 

and Sons, 268 p.

Helsel, D.R., and Cohn, T.A., 1988, Estimation of descriptive 

statistics for multiply censored water quality data: Water 

Resources Research, v. 24, no. 12, p. 1997–2004.

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

water resources: New York, Elsevier Science Publishers, 

522 p.

Hem, J.D., 1992, Study and interpretation of the chemical 

characteristics of natural water (3d ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 263 p.

Hickman, R.E., and Fischer, J.M., 2007, Water quality of 

streams in and near the Delaware Water Gap National 

Recreation Area, Pennsylvania and New Jersey, 2002–04: 

U.S. Geological Survey Scientific Investigations Report 

2007–5290, 65 p.

Hornbeck, J.W., Alexander, M.M., Eagar, Christopher, 

Carlson, J.Y., and Smith, R.B., 2001, Database for chemical 

contents of streams on the White Mountain National Forest: 

U.S. Department of Agriculture, Forest Service General 

Technical Report NE–282, 12 p.

Hubbard Brook Long Term Ecological Research, 2010, 

accessed February 14, 2010, at http://www.hubbardbrook.

org/pubs/pub_search.php

Hyer, K.E., Webb, J.R., and Eshleman, K.N., 1995, Episodic 

acidification of three streams in Shenandoah National Park, 

Virginia, USA: Water, Air, and Soil Pollution, v. 85, 

p. 523–528.

Johnston, C.M., Dewald, T.G., Bondelid, T.R., Worstell, B.B., 

McKay, L.D., Rea, Alan, Moore, R.B., and Goodall, J.L., 

2009, Evaluation of catchment delineation methods for 

the medium-resolution National Hydrography Dataset: 

U.S. Geological Survey Scientific Investigations Report 

2009–5233, 88 p. (Also available at http://pubs.usgs.gov/

sir/2009/5233/pdf/sir2009-5233).

Kahl, J.S., and Scott, Matthew, 1988, Chemistry of Maine’s 

high elevation lakes—Results from the HELM project: 

Lake and Reservoir Management, v. 4, no. 1, p. 33–39.

Kahl, J.S., Stoddard, J.L., Haeuber, Richard, Paulsen, S.G., 

Birnbaum, Rona, Deviney, F.A., Webb, J.R., DeWalle, D.R., 

Sharpe, William, Driscoll, C.T., Herlihy, A.T., Kellogg, J.H., 

Murdoch, P.S., Roy, Karen, Webster, K.E., and Urquhart, 

N.S., 2004, Have U.S. surface waters responded to the 

1990 Clean Air Act Amendments?: Environmental 

Science and Technology, v. 38, no. 24, p. 484A–490A, 

doi: 10.1021/es04046861.

Keys, J. Jr., Carpenter, C., Hooks, S., Koenig, F., McNab, 

W.H., Russell, W., and Smith, M.L., 1995. Ecological 

units of the eastern United States—first approximation 

(CD–ROM), Atlanta, GA: U.S. Department of Agriculture, 

Forest Service. GIS coverage in ARCINFO format, selected 

imagery, and map unit tables. (Also available at 

http://www.srs.fs.usda.gov/econ/data/keys/index.htm).

King, P.B., and Beikman, H.M., 1974, Geologic map of the 

United States: U.S. Geological Survey Professional Paper 

901, 40 p., accessed August 2010, at http://pubs.usgs.gov/

dds/dds11/pp901.pdf.

Latysh, N.E., and Wetherbee, G.A., in press, Improved mapping of National Atmospheric Deposition Program wetdeposition in complex terrain using PRISM-gridded data 

sets: Environmental Monitoring and Assessment.

Lawrence, G.B., 2002, Persistent episodic acidification of 

streams linked to acid rain effects on soil: Atmospheric 

Environment, v. 36, p. 1589–1598.

Lawrence, G.B., Momen, Bahram, and Roy, K.M., 2004, Use 

of stream chemistry for monitoring acidic deposition effects 

in the Adirondack Region of New York: Environmental 

Quality, v. 33, p. 1002–1009.

Likens, G.E., ed., 1985, An ecosystem approach to aquatic 

ecology: New York, Springer-Verlag, 516 p.

Likens, G.E., and Bormann, F.H., 1995, Biogeochemistry of 

a forested ecosystem (2d ed.): New York, Springer-Verlag, 

171 p.

Likens, G.E., and Buso, D.C., 2006, Variations in streamwater 

chemistry throughout the Hubbard Brook Valley: 

Biogeochemistry, v. 78, p. 1–30.

MacKaye, B., 1921, An Appalachian Trail: A Project in 

Regional Planning: Journal of the American Institute of 

Architects, October.

Monteith, D.T., Stoddard, J.L., Evans, C.D., deWit, H.A., 

Forsius, Martin, Høgåsen, Tore, Wilander, Anders, 

Skjelkvåle, B.L., Jeffries, D.S., Vuorenmaa, Jussi, 

Keller, Bill, Kopácek, Jiri, and Vesely, Josef, 2007, 

Dissolved organic carbon trends resulting from changes in 

atmospheric deposition chemistry: Nature, v. 450, no. 2, 

doi:10.1038/nature06316, p. 537–540.

Mueller, D.K., Hamilton, P.A., Helsel, D.R., Hitt, K.J., and 

Ruddy, B.C., 1995. Nutrients in ground water and surface 

water of the United States—an analysis of data through 

1992: U.S. Geological Survey Water Investigations Report, 

1995, 95–4031, p. 74.
References 61

Nadeau, Tracie-Lynn, and Rains, M.C., 2007, Hydrological 

connectivity between headwater streams and downstream 

waters—how science can inform policy: Journal of 

American Water Resources Association, v. 43, no. 1, 

p. 188–133.

National Atmospheric Deposition Program, 1994a, Annual 

sulfate wet deposition, 1994, accessed August 29, 2010, at 

http://nadp.sws.uiuc.edu/ntn/grids.aspx.

National Atmospheric Deposition Program, 1994b, Annual 

nitrate wet deposition, 1994, accessed August 29, 2010, at 

http://nadp.sws.uiuc.edu/ntn/grids.aspx.

National Climatic Data Center, 2005, U.S. Climate Normals, 

accessed August 11, 2010, at http://cdo.ncdc.noaa.gov/

cgi-bin/climatenormals/climatenormals.pl

National Park Service, 1998, Baseline water quality data 

inventory and analysis—Curecanti National Recreation 

Area: National Park Service Technical Report NPS/

NRWRD/NRTR-98/181.

National Park Service, 2008, Appalachian National Scenic 

Trail resource management plan, accessed August 29, 2010, 

at http://www.nps.gov/appa/naturescience/index.htm.

Neff, K.J., Schwartz, J.S., Henry, T.B., Robinson, R.B., 

Moore, S.E., and Kulp, M.A., 2008, Physiological stress in 

native southern brook trout during episodic stream acidification in the Great Smoky Mountains National Parks National 

Park: Environmental Contamination and Toxicology, 

doi: 10.1007/s00244-008-9269-4, 12 p.

PRISM Climate Group, Oregon State University, 2006a, 

United States average monthly or annual maximum 

temperature, 1971–2000, accessed March 25, 2010, at 

http://prismclimate.org.

PRISM Climate Group, Oregon State University, 2006b, 

United States average monthly or annual precipitation, 

1971–2000, accessed March 25, 2010, at 

http://prismclimate.org.

Reed, J.C., and Bush, C.A., 2005, Generalized geologic 

map of the conterminous United States: U.S. Geological 

Survey, National Atlas, accessed August 2010, at 

http://pubs.usgs.gov/atlas/geologic/.

Rice, K.C., and Bricker, O.P., 1995, Seasonal cycles of 

dissolved constituents in streamwater in two forested 

catchments in the mid-Atlantic region of the eastern USA: 

Journal of Hydrology, v. 170, no. 1–4, p. 137–158.

Rice, K.C., Deviney, F.A., Jr., Hornberger, G.M., and Webb, 

J.R., 2005, Predicting the vulnerability of streams to episodic acidification and potential effects on aquatic biota 

in Shenandoah National Park, Virginia: U.S. Geological 

Survey Scientific Investigations Report 2005–5259, 51 p.

Rice, K.C., Deviney, F.A., Jr., and Olsen, Gordon, 2007, 

Acid rain in the Shenandoah National Park, Virginia: 

U.S. Geological Survey Fact Sheet 2007–3057, 4 p.

Robinson, R.B., Barnett, T.W., Harwell, G.R., Moore, S.E., 

Kulp, M.A., and Schwartz, J.S., 2008, pH and acid anion 

time trends in different elevation ranges in the Great Smoky 

Mountains National Park: Journal of Environmental 

Engineering, v. 134, no. 9, p. 800–808.

Rochelle, B.P., and Church, M.R., 1987, Regional patterns of 

sulfur retention in watersheds of the eastern U.S.: Water, 

Air, and Soil Pollution, v. 36, no. 1–2, p. 61–73.

Rosfjord, C.H., Webster, K.E., Kahl, J.S., Norton, S.A., 

Fernandez, I.J., and Herlihy, A.T., 2007, Anthropogenically 

driven changes in chloride complicate interpretation of base 

cation trends in lakes recovering from acidic deposition: 

Environmental Science and Technology, v. 41, p. 7688–

7693.

Rounds, S.A., 2006, Alkalinity and acid neutralizing capacity 

(version 3.0): U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chap. A6, 

section 6.6, July, accessed August 2008, from 

http://pubs.water.usgs.gov/twri9A6/.

SAS Institute, Inc., 2008, SAS OnlineDoc 9.1.3.: Cary, N.C., 

SAS Institute, Inc.

Seaber, P.R., Kapinos, P., and Knapp, G.L., 1987, Hydrologic 

unit maps: U.S. Geological Survey Water-Supply Paper 

2294, 66 p.

Shriver, Greg, Maniero, Tonnie, Schwarzkopf, Kent, 

Lambert, Dan, Dieffenbach, Fred, Owen, Don, Wang, Y.Q., 

Nugranad-Marzilli, Joy, Tierney, Geri, Reese, Casey, and 

Moore, T.T., 2005, Appalachian Trail vital signs: National 

Park Service, Technical Report NPS/NER/NRTR–2005/026, 

86 p.

Shubzda, J., Lindberg, S.E., Garten, C.T., and Nodvin, S.C., 

1995, Elevational trends in the fluxes of sulfur and nitrogen 

in throughfall in the Southern Appalachian Mountains—

Some surprising results: Water, Air, and Soil Pollution, 

v. 85, p. 2265–2270.

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.

Smith, R.A., Alexander, R.B., and Schwarz, G.E., 2003, 

Natural background concentrations of nutrients in streams 

and rivers of the conterminous United States: Environment 

Science & Technology, v. 37, no. 14, p. 3039–3047.
62 Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia

Stoddard, J.L., Kahl, J.S., Deviney, F.A., DeWalle, D.R., 

Driscoll, C.T., Herlihy, A.T., Kellogg, J.H., Murdoch, P.S., 

Webb, J.R., and Webster, K.E., 2003, Response of surface 

water chemistry to the Clean Air Act Amendments of 1990: 

U.S. Environmental Protection Agency, EPA/620/R-03/001, 

78 p.

Stoddard, J.L., Urquhart, N.S., Newell, A.D., and Kugler, 

Danny, 1996, The Temporally Integrated Monitoring 

of Ecosystems (TIME) project design—2, Detection of 

regional acidification trends: Water Resources Research, 

v. 32, no. 8, p. 2529–2538.

Sullivan, T.J., Cosby, B.J., Herlihy, A.T., Webb, J.R., Bulger, 

A.J., Snyder, K.U., Brewer, P.F., Gilbert, E.H., and Moore, 

D.L., 2004, Regional model projections of future effects of 

sulfur and nitrogen deposition on streams in the southern 

Appalachian Mountains: Water Resources Research, v. 40, 

p. 1–16. 

Sullivan, T.J., Webb, J.R., Snyder, K.U., Herlihy, A.T., and 

Cosby, B.J., 2007, Spatial distribution of acid-sensitive and 

acid-impacted streams in relation to watershed features in 

the Southern Appalachian Mountains: Water, Air, and Soil 

Pollution, v. 182, p. 57–71.

University of Virginia, Department of Environmental 

Sciences, 2010, Shenandoah Watershed and Virginia Trout 

Stream Sensitivity Study accessed February 15, 2010, at 

http://swas.evsc.virginia.edu/#javascript.

U.S. Census, 2003, Locating urbanized area and urban 

cluster boundaries, accessed August 27, 2010, at 

http://www.census.gov/geo/www/ua/uaucbndy.html.

U.S. Department of Agriculture, Natural Resources 

Conservation Service, 2005, Watershed Boundary Dataset, 

accessed March 15, 2010, at http://www.ncgc.nrcs.usda.

gov/products/datasets/watershed/.

U.S. Department of Agriculture, Natural Resources 

Conservation Service, Soil Survey Staff, updated 2006, 

U.S. General Soil Map (STATSGO2) for [State], accessed 

August 17, 2010, at http://soildatamart.nrcs.usda.

U.S. Department of Commerce, National Climatic Data 

Center, 2003, Climatography of the U.S. No. 85—Monthly 

divisional normals and standard deviations, accessed August 

23, 2010, at http://www.ncdc.noaa.gov/oa/climate/normals/

usnormals.html.

U.S. Environmental Protection Agency, 2000, Nutrient 

Criteria: Technical guidance manual; rivers and streams: 

U.S. Environmental Protection Agency, EPA 822B-00-

002, 253 p., accessed June 2, 2011, at http://water.epa.

gov/scitech/swguidance/standards/criteria/nutrients/

upload/2009_04_22_criteria_nutrient_guidance_rivers_

rivers-streams-full.pdf. 

U.S. Environmental Protection Agency, 2002a, Quality 

Criteria for Water 1986: U.S. Environmental Protection 

Agency, Office of Water, EPA 440/5–86–001, 477 p., 

accessed September 10, 2010, at http://water.epa.gov/

scitech/swguidance/waterquality/standards/criteria/aqlife/

upload/2009_01_13_criteria_goldbook.pdf.

U.S. Environmental Protection Agency, 2002b, Summary table 

for the nutrient criteria documents: U.S. Environmental 

Protection Agency, Office of Water, 3 p., accessed August 

30, 2010, at http://www.epa.gov/waterscience/criteria/

nutrient/ecoregions/files/sumtable.pdf.

U.S. Environmental Protection Agency, 2006a, National 

Hydrography Dataset Plus, accessed August 29, 2010, at 

http://www.epa.gov/waters.

U.S. Environmental Protection Agency, 2006b, National recommended water quality criteria, accessed August 29, 2010, 

at http://www.epa.gov/waterscience/criteria/wqcriteria.html.

U.S. Environmental Protection Agency, 2006c, Wadeable 

streams assessment—Assessing the nation’s waters: U.S. 

Environmental Protection Agency EPA–841–F–06–001, 2 p.

U.S. Environmental Protection Agency, 2010a, Acid Rain 

Program progress—2009 environmental results, accessed 

March 3, 2011, at http://www.epa.gov/airmarkets/progress/

ARP09_3.html.

U.S. Environmental Protection Agency, 2010b, Temporally 

Integrated Monitoring of Ecosystems and Long-Term 

Monitoring access March 1, 2010, at http://www.epa.gov/

airmarkt/assessments/TIMELTM.html 

U.S. Environmental Protection Agency, 2010c, National 

Stream Survey Data Sets, accessed March 1, 2010, at 

http://www.epa.gov/emap2/html/data/surfwatr/data/nss.html

U.S. Geological Survey, 2000, National land cover dataset 

1992 (NLCD): completed nationwide September 2000, 

accessed August 29, 2010, at http://seamless.usgs.gov/

products/nlcd92.php.

Webb, J.R., Cosby, B.J., Deviney, F.A., Jr., Galloway, J.N., 

Maben, S.W., and Bulger, A.J., 2004, Are brook trout 

streams in Western Virginia and Shenandoah National Park 

recovering from acidification?: Environmental Science and 

Technology, v. 38, no. 15, p. 4091–4096.

Wigington, P.J., Baker, J.P., DeWalle, D.R., Kretser, W.A., 

Murdoch, P.S., Simonin, H.A., Van Sickle, J., McDowell, 

M.K., Peck, D.V., and Barchet, W.R., 1996, Episodic acidification of small streams in the northeastern United States—

Ionic controls of episodes: Ecological Applications, v. 6, 

no. 2, p. 389–407.
Appendix 1 63

Appendix 1. Ancillary and Water-Quality 

Variable Definitions and Catchment Data 

(on CD–ROM)
Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

New Hampshire-Vermont Water Science Center

331 Commerce Way, Suite 2

Pembroke, NH 03275

dc_nh@usgs.gov

or visit our Web site at:

http://nh.water.usgs.gov
Argue and others—Major-Ion Chemistry and Nutrients in Headwater Streams Along the Appalachian National Scenic Trail, Maine to Georgia—SIR 2011–5151

Printed on recycled paper