Effects of Historical Coal Mining

and Drainage from Abandoned Mines 

on Streamflow and Water Quality

in Bear Creek, Dauphin County, 

Pennsylvania—March 1999–

December 2002

By Jeffrey J. Chaplin

U.S. Department of the Interior 

U.S. Geological Survey

In cooperation with the Dauphin County Conservation District

Scientific Investigations Report 2005-5042
ii 

Suggested citation:

Chaplin, J.J., 2005, Effects of historical coal mining and drainage from abandoned mines on streamflow and water 

quality in Bear Creek, Dauphin County, Pennsylvania—March 1999-December 2002: U.S. Geological Survey Scientific 

Investigations Report 2005-5042, 45 p.

U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey, Information Services 

Box 25286, Denver Federal Center 

Denver, CO 80225

For more information about the USGS and its products: 

Telephone: 1-888-ASK-USGS 

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

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

endorsement by the U.S. Government.

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.
 iii

Contents

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

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

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

Description of Study Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Geologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Mining History and Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Origin of Mine Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Previous Investigations of Mine Drainage in Bear Creek Watershed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Study Design and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Effects of Historical Coal Mining on Streamflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Effects of Drainage From Abandoned Mines on Water Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Net Acid Neutralizing Capacity (ANC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Specific Conductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Dissolved Oxygen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Manganese. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Aluminum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Metal Loading Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Passive-Treatment Technologies for Iron Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

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

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
iv 

Figures

1. Map showing locations, sampling sites, historical coal-mining features, geologic

cross sections, and proposed treatment within and proximate to Bear Creek watershed,

Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Geologic cross section M-M’ showing anthracite coal-bearing strata in Bear Creek

watershed, Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. Geologic cross section Q-Q’ showing anthracite coal-bearing strata in Bear Creek

watershed, Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4-6. Photographs showing: 

4. Mine drainage discharging from the Lykens Water-Level Tunnel (LWLT) in 

Bear Creek watershed, Dauphin County, Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5. Mine drainage discharging from the Lykens Drift (LD) discharge in Bear Creek

watershed, Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6. Mine drainage from several seeps adjacent to the Lykens Drift discharge in 

Bear Creek watershed, Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7. Streamflow hydrograph for Bear Creek downstream of mine inputs (BC-DMD) 

superimposed on instantaneous streamflow measurements upstream of mine inputs 

(BC-UMD), and precipitation measured approximately 8.5 miles southwest of Bear Creek

at DeHart Reservoir Dam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8. Pie chart showing percent contribution of base flow (A) and stormflow (B) to Bear Creek

downstream of mine drainage (BC-DMD) computed as the mean ratio of instantaneous 

flow at sites Bear Creek upstream of mine drainage (BC-UMD), Lykens Water-Level

Tunnel (LWLT), and Lykens Drift (LD) to instantaneous flow at site BC-DMD. . . . . . . . . . . . . . . . . 17

9-20. Graphs showing:

9. Ranges of net acid neutralizing capacity measured at seven sites in the Bear 

Creek study area, Dauphin County, Pennsylvania, from March 1999 to 

December 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

10. Relation of net acid neutralizing capacity to flow at seven sites in the Bear Creek 

study area, Dauphin County, Pennsylvania, from March 1999 to December 2002 . . . . . . 24

11. Ranges of specific conductance measured at seven sites in the Bear Creek 

study area, Dauphin County, Pennsylvania, from March 1999 to December 2002 . . . . . . 26

12. Relation of specific conductance to flow at seven sites in the Bear Creek study 

area, Dauphin County, Pennsylvania, from March 1999 to December 2002 . . . . . . . . . . . . 27

13. Ranges of dissolved oxygen measured at seven sites in the Bear Creek study 

area, Dauphin County, Pennsylvania, from March 1999 to December 2002 . . . . . . . . . . . . 29

14. Relation of dissolved oxygen to flow at seven sites in the Bear Creek study area, 

Dauphin County, Pennsylvania, from March 1999 to December 2002. . . . . . . . . . . . . . . . . . 30

15. Ranges of pH measured at seven sites in the Bear Creek study area, Dauphin 

County, Pennsylvania, from March 1999 to December 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

16. Relation of pH to flow at seven sites in the Bear Creek study area, Dauphin 

County, Pennsylvania, from March 1999 to December 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

17. Ranges of dissolved and total iron measured at seven sites in the Bear Creek 

study area, Dauphin County, Pennsylvania, from March 1999 to December 2002 . . . . . . 34

18. Relation of dissolved and total iron to flow at seven sites in the Bear Creek study 

area, Dauphin County Pennsylvania, from March 1999 to December 2002. . . . . . . . . . . . . 36

19. Ranges of dissolved and total manganese measured at seven sites in the Bear 

Creek study area, Dauphin County, Pennsylvania, from March 1999 to December 

2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
 v

Figures—Continued

9-20. Graphs showing—Continued:

20. Relation of dissolved and total manganese to flow at seven sites in the Bear 

Creek study area, Dauphin County, Pennsylvania, from March 1999 to

December 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

21. Sketch showing mean loading rates of total iron (FE) and manganese (MN) in the

Bear Creek study area, Dauphin County, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

22. Flow chart of passive-treatment alternatives adapted from Hedin and others (1994)

and Skousen and others (2000) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Tables

1. Water-quality standards and Total Maximum Daily Loads for iron and manganese at the

mouth of Bear Creek, Dauphin County, Pennsylvania.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

2. Sampling sites in the Bear Creek and Wiconisco Creek watersheds, Dauphin County, 

Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3. Comparison of selected constituents in duplicate samples analyzed separately by the 

Pennsylvania Department of Environmental Protection Laboratory and the U.S. Geological 

Survey National Water-Quality Laboratory.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4. Summary of instantaneous flow data collected at nine sites on Bear Creek and two sites 

on Wiconisco Creek, Dauphin County, Pennsylvania, from March 1999 to December 2002.. . . . . . . . 16

5. Summary statistics for water-quality data collected at nine sites on Bear Creek and two sites

on Wiconisco Creek, Dauphin County, Pennsylvania, from March 1999 to December 2002.. . . . . . . . 20

6. Results of statistical analyses performed on four paired sites in the Bear Creek study area, 

Dauphin County, Pennsylvania.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

7. Computed mean loads of dissolved iron and total manganese compared to Total Maximum 

Daily Loads at selected sites in the Bear Creek watershed, Dauphin County, Pennsylvania. . . . . . . . 39
vi 

Conversion Factors, Abbreviated Water-Quality 

Units, and Datum

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 National Geodetic Vertical Datum of 1929 

(NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27) 

and the North American Datum of 1983 (NAD 83).

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

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 either in milligrams per liter (mg/L) or 

micrograms per liter (μg/L).

Other abbreviations:

mL, milliliter

mV, millivolt

μm, micrometer

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

gallon (gal) 0.003785 cubic meter (m3)

cubic foot (ft3) 0.02832 cubic meter (m3)

billion gallons (bgal) 0.13368 cubic feet (ft3)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

cubic foot per second (ft3/s) 448.9 gallon per minute

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg)
Effects of Historical Coal Mining and Drainage From 

Abandoned Mines on Streamflow and Water Quality 

in Bear Creek, Dauphin County, Pennsylvania—

March 1999–December 2002

By Jeffrey J. Chaplin

Abstract

More than 100 years of anthracite coal mining has changed 

surface- and ground-water hydrology and contaminated streams 

draining the Southern Anthracite Coal Field in east-central 

Pennsylvania. Bear Creek drains the western prong of the 

Southern Anthracite Coal Field and is affected by metals in 

drainage from abandoned mines and streamwater losses. Total 

Maximum Daily Loads (TMDL) developed for dissolved iron 

of about 5 lb/d (pounds per day) commonly are exceeded in the 

reach downstream of mine discharges. Restoration of Bear 

Creek using aerobic ponds to passively remove iron in abandoned mine drainage is under consideration (2004) by the Dauphin County Conservation District. This report, prepared in 

cooperation with the Dauphin County Conservation District, 

evaluates chemical and hydrologic data collected in Bear Creek 

and its receiving waters prior to implementation of mine-drainage treatment. The data collected represent the type of baseline 

information needed for documentation of water-quality changes 

following passive treatment of mine drainage in Pennsylvania 

and in other similar hydrogeologic settings.

Seven surface-water sites on Bear Creek and two mine discharges were monitored for nearly three years to characterize 

the chemistry and hydrology of the following: (1) Bear Creek 

upstream of the mine discharges (BC-UMD), (2) water draining 

from the Lykens-Williamstown Mine Pool at the Lykens 

Water-Level Tunnel (LWLT) and Lykens Drift (LD) discharges, (3) Bear Creek after mixing with the mine discharges 

(BC-DMD), and (4) Bear Creek prior to mixing with Wiconisco 

Creek (BCM). Two sites on Wiconisco Creek, upstream and 

downstream of Bear Creek (WC-UBC and WC-DBC, respectively), were selected to evaluate changes in streamflow and 

water quality upon mixing with Bear Creek. 

During periods of below-normal precipitation, streamwater loss was commonly 100 percent upstream of site BC-UMD 

(streamflow range = 0 to 9.7 ft3/s (cubic feet per second)) but no 

loss was detected downstream owing to sustained mine water 

drainage from the Lykens Water-Level Tunnel (range = 0.41 to 

3.7 ft3/s), Lykens Drift (range = 0.40 to 6.1 ft3/s), and diffuse 

zones of seepage. Collectively, mine water inputs contributed 

about 84 percent of base flow and 53 percent of stormflow measured in the downstream reach. 

An option under consideration by the Dauphin County 

Conservation District for treatment of the discharge from the 

LWLT requires the source of the discharge to be captured and 

rerouted downstream, bypassing approximately 1,000 feet of 

stream channel. Because streamwater loss upstream of the tunnel was commonly 100 percent, rerouting the discharge from 

the LWLT may extend the reach of Bear Creek that is subject to 

dryness. 

Differences in the chemistry of water discharging from the 

LWLT compared to the LD suggest that the flow path through 

the Lykens-Williamstown Mine Pool to each mine discharge is 

unique. The LWLT is marginally alkaline (median net acid neutralizing capacity (ANC) = 9 mg/L (milligrams per liter) as 

CaCO3; median pH = 5.9), commonly becomes acidic (minimum net ANC = -74 mg/L as CaCO3) at low flow, and may 

benefit from alkaline amendments prior to passive treatment. 

Water discharging from the LD provides excess ANC (median 

net ANC = 123 mg/L as CaCO3; median pH = 6.5) to the downstream reach and is nearly anoxic at its source (median dissolved oxygen = 0.5 mg/L). Low dissolved oxygen water with 

relatively high ANC and metals concentrations discharging 

from the LD is characteristic of a deeper flow path and longer 

residence time within the mine pool than the more acidic, oxygenated water discharging from the LWLT.

TMDLs for iron have been developed for dissolved species only. Consequently, distinguishing between dissolved and 

suspended iron in Bear Creek is important for evaluating waterquality improvement through TMDL attainment. Median total 

iron concentration increased from 550 μg/L (micrograms per 

liter) at site BC-UMD (mean load of approximately 5 lb/d) to 

10,600 μg/L at site BCM (mean load of 540 lb/d) but the TMDL 

was met at site BCM approximately 10 percent of the time 

because most of the iron at that site is suspended. Water draining from LWLT (median dissolved iron concentration = 

5,170 μg/L) and LD (median dissolved iron concentration = 

18,300 μg/L) undergoes oxidation and hydrolysis quickly. As a 

result, TMDL attainment at site BCM is a consequence of dissolved iron converting to suspended solids but is not indicative 

of improvement in water quality or benefits to aquatic life. To 
2 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

properly interpret any improvement achieved through attainment of TMDLs developed for dissolved constituents, data for 

the corresponding suspended fraction are essential. 

Introduction

Anthracite coal-bearing strata underlying the Bear Creek 

watershed in Dauphin County, Pa. (fig. 1), and adjacent basins 

in the Southern Anthracite Coal Field were mined extensively 

by surface stripping and underground methods beginning in the 

early 1800s (Wood and others, 1969). By the early 1900s, the 

most readily accessible coal had been mined, leaving behind 

only the deep seams that required expensive dewatering to 

extract. As the expense of coal extraction became prohibitive, 

mining in the Bear Creek watershed slowed, ceasing altogether 

in the 1930s (Wood and others, 1969). When mining ceased, 

many surface workings were left as open pits with some openings having connections to the deep underground mines. In the 

absence of dewatering pumps, surface runoff and ground-water 

seepage eventually flooded the underground mines, and a new 

hydrologic balance was established. Metal-laden water once 

pumped from the mines overflowed through tunnels and drift 

openings to Bear Creek.

As a consequence of receiving metal-laden drainage from 

the abandoned underground mines, Bear Creek commonly 

exceeds Total Maximum Daily Loads (TMDLs) developed for 

the watershed (Susquehanna River Basin Commission, 2001) 

and water-quality standards for its designated use as a coldwater fishery (Pennsylvania Department of Environmental Protection, 1998) (table 1). Iron loading is the largest contamination source limiting aquatic life in Bear Creek (Susquehanna 

River Basin Commission, 2001; Hedin Environmental, 1998; 

Stoe, 1998; Sanders and Thomas, Inc., 1973). Wiconisco Creek, 

which supports a viable trout population (Charles McGarrell, 

Pennsylvania Department of Environmental Protection, oral 

commun., 2000), also is compromised by metals loading in the 

reach downstream of Bear Creek.

Degradation of habitat and water quality from mine drainage entering Bear Creek has been recognized for decades 

(Sanders and Thomas, Inc.,1973; Stoe, 1998). Despite this, the 

problem currently (2004) is unchecked. Passive-treatment technologies developed in the mid-1990s reduce the costs of infrastructure, chemical amendments, and maintenance of conventional treatment (Hedin and others, 1994). Because of these 

developments, passive treatment is now under consideration by 

the Dauphin County Conservation District (DCCD) to reduce 

metals loading in Bear Creek and ultimately achieve compliance with established TMDLs. 

DCCD, through the Pennsylvania Department of Environmental Protection (PaDEP) Growing Greener Program, and the 

U.S. Geological Survey (USGS) cooperated in an investigation 

from March 1999 to December 2002 to characterize the effects 

of historical coal mining and drainage from abandoned mines 

on streamflow and water quality in Bear Creek. Data collected 

during this investigation may be useful to water-resources managers and the private sector in design of passive-treatment systems. For example, see Hedin Environmental (2001) and Skelly 

and Loy, Inc. (2003) for passive-treatment alternatives to 

reduce iron loading in abandoned mine drainage before it mixes 

with Bear Creek. The data collected represent the type of baseline information needed for documentation of water-quality 

changes following passive treatment of mine drainage in Pennsylvania and in other similar hydrogeologic settings.

Purpose and Scope

This report provides hydrologic and chemical data for 

determining the effect of historical coal mining and drainage 

from abandoned mines on Bear Creek and its receiving waters. 

The evaluations in this report are based on hydrologic and 

chemical data collected between March 1999 and December 

2002 by the USGS at seven stream sites on Bear Creek, two 

mine discharges entering Bear Creek, and two stream sites on 

Wiconisco Creek (one upstream and one downstream of Bear 

Creek). Hydrologic data consist of continuous (15-minute interval) flow determination at one site and instantaneous flow 

determinations at all other sites. Data for 18 chemical constituents are reported and those that are most useful for interpreting 

the effects of drainage from abandoned mines on Bear Creek are 

discussed in detail. These constituents include acid neutralizing 

capacity (ANC), specific conductance, dissolved oxygen, pH, 

iron, manganese, and aluminum. This report also discusses passive-treatment technologies as options to remove iron from 

mine discharges. 

Table 1. Water-quality standards and Total Maximum Daily Loads 

for iron and manganese at the mouth of Bear Creek, 

Dauphin County, Pennsylvania.

[μg/L, micrograms per liter; TMDL, Total Maximum Daily Load; 

--, not determined]

Constituent

Water-quality 

standard

(μg/L)1

1Pennsylvania Department of Environmental Protection, 1998.

TMDL

(pounds per day)2

2Total Maximum Daily Load at the mouth of Bear Creek (Susquehanna River Basin Commission, 2001).

Iron, total 3 1,500

3Daily mean concentration.

--

Iron, dissolved 4 300

4Maximum concentration.

6

Manganese, total 4 1,000 24
Figure 1. Locations, sampling sites, historical coal-mining features, geologic cross sections, and proposed treatment within and proximate watershed, Dauphin County, Pennsylvania. Watershed boundaries and streams are digitized from Lykens, and Tower City, Pennsylvania, 7.5 minute, 1:24000, quadr

Anthracite Coal Region is from Map 11 of the Pennsylvania Department of Conservation and Natural Resources (2000). Lykens-Williamstown Mine Pool boundaries and locatioare digitized from maps published by Ash and others (1949) and Ash and Kynor (1953). [WC-UBC, Wiconisco Creek upstream of Bear Creek; BCH-A, Bear Creek at headwaters Creek at headwaters - B; BCH-C, Bear Creek at headwaters - C; BCH-D, Bear Creek at headwaters - D; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]
4 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Description of Study Area

Bear Creek drains the northwestern prong of the Southern 

Anthracite Coal Field in the Ridge and Valley Physiographic 

Province, south-central Pennsylvania (fig. 1). The headwaters 

of the creek flow from a wetland between Bear and Big Lick 

Mountains. The creek flows for a distance of 4.5 mi where it 

discharges into Wiconisco Creek. The watershed is 4.7 mi2, is 

mostly forested, and has been extensively mined on the surface 

and underground. Remnant mining features, including cropfalls and strip pits, are scattered throughout the watershed and 

convey a portion of surface runoff to underground mine workings (Skelly and Loy, Inc., 2003). The underground mine workings are collectively referred to as the Lykens-Williamstown 

Mine Pool (fig. 1), which discharges metal-laden drainage from 

Lykens Water-Level Tunnel (LWLT), Lykens Drift (LD), and 

diffuse zones of seepage to Bear Creek. A sewage-treatment 

plant, approximately 0.25 mi above the mouth of Bear Creek, 

discharges treated effluent to Bear Creek. The plant is designed 

for a maximum influent flow of 125,000 gal per day; average 

monthly effluent limits for total suspended solids, dissolved 

oxygen, and pH are 45 mg/L, greater than 5 mg/L, and between 

6 - 9 standard units, respectively (Pennsylvania Department of 

Environmental Protection, 1996). 

Geologic Setting

Three principal formations, the Mauch Chunk, Pottsville, 

and Llewellyn, underlay the Bear Creek watershed and adjacent 

areas of the Southern Anthracite Coal Field (figs. 2 and 3). The 

Mauch Chunk Formation is of Late Mississippian and Early 

Pennsylvanian age and is successively overlain by the coalbearing Pottsville and Llewellyn Formations of Pennsylvanian 

age. The structural geology of these formations is complex 

(Wood and others, 1969; Wood and others, 1986). The Pottsville and Llewellyn Formations are characterized by tightly 

folded coal-bearing rock units that are interrupted by numerous 

faults (figs. 2 and 3). Some faults extend into the underlying 

Mauch Chunk Formation and may facilitate mixing of ground 

water between formations. Natural outcrops are rare (Wood and 

others, 1969), but rocks are exposed in many areas by strip pits 

and road cuts. 

The Mauch Chunk Formation commonly ranges from 200 

to 500 ft thick in the Anthracite Coal Region but may be as 

much as 800 ft thick in the vicinity of Bear Creek (Wood and 

others, 1986). The formation is divided into three informal 

members; the Upper, Middle, and Lower Members (Wood and 

others, 1986). Because differentiation of these members is complicated by lack of stratigraphic markers, faulting, and folding 

(Wood and others, 1986), they are not identified in figures 2 

and 3. The lithology of the Mauch Chunk Formation is characterized by varying thickness and is composed of red and gray 

conglomerate, sandstone, siltstone, and shale (Wood and others, 

1986). Cementing media include silica, limonite, hematite, unidentified clay minerals, sericite, and calcite (Wood and others, 

1969). 

The Pottsville Formation includes all strata between the 

underlying Mauch Chunk and overlying Llewellyn Formations 

and is divided into the Tumbling Run Member, the Schuylkill 

Member, and the Sharp Mountain Member (figs. 2 and 3) 

(Wood and others, 1956). The Tumbling Run Member is 

approximately 600 ft thick and contains six anthracite coal 

beds. Three of these beds are known to have been mined 

(Lykens Valley Nos. 4, 5, and 6) (figs. 2 and 3). The Tumbling 

Run Member is overlain by the Schuylkill Member, which is 

approximately 700 ft thick. Four persistent and several nonpersistent anthracite beds have been identified. The four persistent 

coal beds are Lykens Valley Nos. 3, 2, 1-1/2, and 1 (figs. 2 

and 3). The Sharp Mountain Member is about 400 ft thick, is 

composed chiefly of coarse conglomerate, and contains several 

non-persistent coal beds in the study area (figs. 2 and 3). Noncoal-bearing strata include fine- to coarse-grained sandstone, 

conglomerate, conglomeratic sandstone, shale, and siltstone 

(Wood and others, 1969). Pebbles in conglomerate and conglomeratic rocks are composed largely of vein quartz and 

quartzite. Cementing media include silica, sericite, unidentified 

clay minerals, and calcite (Wood and others, 1969). 

The Llewellyn Formation overlies the Sharp Mountain 

member of the Pottsville Formation. The base of this formation 

is the base of the shale or underclay below the No. 5 coal bed 

or, where the shale is absent, at the base of the coal (figs. 2 

and 3). The upper limit of the Llewellyn is the present erosional 

surface except where covered by talus (Wood and others, 1986). 

Although as many as 40 coal seams are present in the west-central part of the Southern Anthracite Coal Field (Wood and others, 1969) approximately 15 are persistent in the study area 

(figs. 2 and 3). Thickness ranges from 400 ft in the lower part 

of Bear Creek watershed to 2,400 ft thick in the headwaters 

(figs. 2 and 3). The lithology of non-coal-bearing strata is characterized by scattered conglomerate, conglomeratic sandstone, 

and fine- to coarse-grained sandstone (Wood and Trexler, 

1968). The rocks of the Llewellyn Formation are cemented 

principally by silica, sericite, and silt- and clay-sized fragments 

of quartz and carbonaceous material. 

Mining History and Techniques

The Pottsville and Llewellyn Formations hold some of the 

richest anthracite reserves in the United States (Wood and others, 1969). The anthracite mining industry became economically important between 1825 and 1835 (Wood and others, 

1969), owing to demand from a growing steel industry supplied 

by a new railroad network that extended throughout eastern 

Pennsylvania, Delaware, New Jersey, and Maryland. These 

developments provided the market and infrastructure for largescale coal-mining operations that continued into the 1930s. The 

collier chiefly responsible for coal extraction within and underlying the Bear Creek watershed was the Lykens-Williamstown 
Figure 2. Geologic cross section M-M’ showing anthracite coal-bearing strata in Bear Creek watershed, Dauphin County, Pennsylvania. Locati

shown on figure 1. Cross section is adapted from Wood and Trexler (1968). 
6 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Mine of the Rhoads Contracting Company (Ash and Kynor, 

1953). 

The Lykens-Williamstown Mine is bounded by the lowest 

workable coal bed (LV7 where present, otherwise LV6) and is 

adjoined by the Valley View and Brookside Mines to the east 

(fig. 1). Valley View Mine is north of and adjacent to Brookside 

Mine; however, the exact boundary is unclear and is therefore 

not shown on figure 1. The boundary between the Lykens-Williamstown Mine and the adjoining mines is the mine pool 

boundary where no barrier pillars exist. Where no adjoining 

mines are present, the boundary of Lykens-Williamstown Mine 

is the lowest workable coal bed (fig. 1).

Strip mining, the removal of coal from surface outcroppings, was utilized wherever coal was accessible at or near the 

erosional surface, mainly on the south-facing slope of Bear 

Mountain, north and south-facing slopes of Short Mountain, 

and the north slope of Big Lick Mountain. Overburden (overlying nonmarketable strata) was removed with power shovels and 

bulldozers and typically discarded on the downslope side. Coal 

extraction generally progressed until the mine depth restricted 

the use of machinery, rendering the method unprofitable. Coal 

seams 9T, 9, 8, 7, 5T, LV6, LV5, LV4, and LV3 7/8 (figs. 2 

and 3) were strip mined (Wood and others, 1969). 

Drift mining was employed where multiple entries in close 

proximity could be excavated into an outcropping coal bed that 

did not dip too steeply (less than 20° inclination from horizontal) (Wood and others, 1969). Drift entries can extend for hundreds of feet until they are eventually connected by cross entries 

Figure 3. Geologic cross section Q-Q’ showing anthracite coal-bearing strata in Bear Creek watershed, Dauphin County, 

Pennsylvania. Location of section is shown on figure 1. Cross section is adapted from Wood and Trexler (1968). The Lykens 

Water-Level Tunnel is referred to as Short Mountain Tunnel by Wood and Trexler (1968). 
Introduction 7

(Sanders and Thomas, Inc., 1973). This type of mining results 

in a framework of rooms and pillars by excavating “rooms” 

supported by “pillars” that are left in place. Log timbers commonly were used as additional support. After completion of a 

series of rooms and removal of excavated coal, the pillars generally were removed or “robbed,” usually resulting in collapse 

of the workings. Lykens Drift (fig. 1) and adjacent seeps are a 

result of drift mining.

Deep mining is similar to drift mining in that it involves 

coal extraction by tunneling into and excavating rooms and pillars from a coal bed. This method typically was used where the 

dip of the coal bed was greater than 20°. Shafts are excavated 

such that they follow the dip of the coal bed and are used for 

access and extraction. Approximately 15 shafts in or close to the 

Bear Creek watershed were identified by Wood and Trexler 

(1968). Some of these have been backfilled through various reclamation efforts or mass wasting of unsupported, adjacent 

strata, but shafts that have not been backfilled are still present 

(Skelly and Loy, Inc., 2003). Coal seams mined too close to the 

surface commonly collapse leaving a hole that may extend hundreds of feet. If these openings are not sealed by collapse of 

adjacent strata or by human intervention, they provide direct 

access for surface runoff to enter the underground mine workings. These holes are referred to as “crop falls.” Most crop falls 

are sealed at the bottom with soil and rock, but about eight 

remain open and may extend hundreds of feet underground. 

Origin of Mine Water

Underground mining has resulted in a vast series of voids 

in the numerous mined coal beds that are interconnected at 

many places but are isolated at others. This series of voids and 

associated tunnels, drifts, and shafts are collectively referred to 

as mine workings. During active mining, water was pumped 

from the mine workings to keep infiltration from the surface 

and ground water out of the mine. These efforts allowed coal 

extraction to proceed well below the local ground-water table; 

in fact, well below sea level (Wood and others, 1969). It commonly is reported that mining in the Bear Creek watershed 

ceased sometime in the 1930s (Ash and others, 1949; Wood and 

others, 1969; Sanders and Thomas, Inc., 1973). Around this 

time, pumping also ceased and the workings flooded with water 

creating the Lykens-Williamstown Mine Pool. The workings 

may be completely flooded in places or may be discontinuously 

flooded in a vertical and horizontal plane. Vertical barrier pillars were left between mines to minimize inter-mine infiltration, 

but when mining efforts were abandoned, the pillars commonly 

were breached by robbing any remaining coal. Barrier pillars 

between the Lykens-Williamstown Mine and the adjoining 

Brookside and Valley View Mines (fig. 1) were not breached as 

recently as 1953 (Ash and Kynor, 1953) and may still provide 

an effective barrier to inter-mine seepage. The present condition 

of these pillars is unknown, and therefore, the degree of interconnection between the Lykens-Williamstown Mine and the 

adjoining mines is unknown. 

The Lykens-Williamstown Mine Pool receives water from 

two known sources: (1) direct connection with the surface 

through the original mine openings and fractures in overlying 

strata, and (2) ground-water seepage from adjacent strata. Seepage from the Brookside Mine Pool to the Lykens-Williamstown 

Mine Pool is another possible source depending on the condition of the barrier pillar between these pools. 

Surface runoff is conveyed through abandoned stripping 

operations, crop falls, and subsidence depressions, which are 

common features throughout the watershed. Fractures in strata 

overlying the mine workings increase infiltration of runoff 

across the entire area and are of particular concern where the 

streambed is intercepted. Nonetheless, a study completed by 

Skelly and Loy, Inc. (2003) indicates water entering the mine 

pool through mine openings accounts for only about 13 percent 

of mine water discharged to Bear Creek. Because there was no 

interflow between adjacent mines as late as 1953 (Ash and 

Kynor, 1953) and conveyance through surface openings 

accounts for 13 percent of mine discharge to Bear Creek, the 

majority of water entering the mine workings is likely provided 

by ground-water seepage from adjacent strata. 

Water entering the mine workings is the reaction and transport medium for the reaction products of metal-bearing minerals. Pyrite (chemically described as iron sulfide (FeS2)) is common in coal-bearing strata (Stumm and Morgan, 1996) and is 

the principal source of iron, the contaminant that has the largest 

effect on the habitat water quality of Bear Creek. Siderite 

(FeCO3) also may be a source of iron and is notable as a source 

of manganese when manganese substitutes for iron (Morrison 

and others, 1990) to form manganosiderite [(Fe, Mn)CO3] (Cravotta and others, 1994). Manganese oxides are also sources of 

manganese in sedimentary rocks (Hem, 1985, p. 88-89). Other 

metals, including aluminum, can originate from the dissolution 

of aluminosilicate minerals (Cravotta, 1991). Because iron is 

the metal that has the largest effect on the water quality of Bear 

Creek, the following discussion focuses on iron production via 

the oxidation of pyrite. 

Mining techniques described above expose the surface of 

pyrite-bearing strata, subjecting it to oxidation. Pyrite oxidation 

is characterized by the following reaction in which pyrite, oxygen, and water react to form ferric hydroxide (Fe(OH)3 (s)), sulfate (SO4

2-), hydrogen ion (H+), and heat:

FeS2(s) + 3.75 O2 + 3.5 H2O = Fe(OH)3(s) + 2 SO4

2-

+ 4 H+ + heat (1)

The presence of ferrous iron (Fe2+) in mine-discharge 

samples collected during this study indicates the chemical reactions are at intermediate stages in a series of reactions that collectively represent pyrite oxidation (Rose and Cravotta, 1998). 

The following reactions characterize various stages in the complete reaction (Stumm and Morgan, 1996):

FeS2(s) + 3.5 O2 + H2O = Fe2+ + 2 SO4

2- + 2 H+ (2)

Fe2+ + 0.25 O2 + H+ = Fe3+ + 0.5 H2O (3)
8 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Fe3+ + 3 H2O = Fe(OH)3(s) + 3 H+ (4)

FeS2(s) + 14 Fe3+ + 8 H2O = 15 Fe2+ + 2 SO4

2- + 16 H+ (5)

Oxidation of FeS2 releases SO4

2-, Fe2+, and H+ into the 

water (eqn. 2). Dissolved Fe2+ undergoes oxidation to Fe3+

(eqn. 3), which then hydrolyzes to form various amorphous 

oxide, hydroxide, or oxyhydroxysulfate precipitates, nominally 

designated here as Fe(OH)3 (s) (eqn. 4). Fe3+ can also be 

reduced by FeS2(s), where FeS2(s) is again oxidized and Fe2+ is 

produced and may re-enter the reaction cycle via equation 3 

(Stumm and Morgan, 1996). 

Water drains from the Lykens-Williamstown Mine Pool 

from the following known sources in Bear Creek watershed: 

(1) LWLT, (2) LD, and (3) diffuse zones of seepage. The 

LWLT extends north underneath Short Mountain where it connects to the Lykens-Williamstown Mine Pool. Mine drainage is 

discharged from the tunnel (fig. 4) onto the east-facing slope of 

Short Mountain and cascades downslope for approximately 

200 ft until its confluence with an unnamed tributary on the 

west side of Bear Creek. The mixed waters are conveyed within 

the unnamed tributary for approximately 50 ft before joining 

Bear Creek.

The LD (fig. 5) is a drift opening that extends horizontally 

underneath Short Mountain where it intercepts the mine pool. 

Mine drainage is discharged approximately 50 ft to the west of 

Bear Creek where it cascades over deposits of solid iron precipitate before entering the creek.

Currently (2004), there are at least three perennially flowing zones of diffuse mine seepage in the watershed. Intermittent 

zones of seepage have not been enumerated. The largest zone of 

diffuse seepage is adjacent to the LD. Historically four separate 

sources were reported near LD in an assessment of Wiconisco 

Creek watershed in 1973 (Sanders and Thomas, Inc., 1973). 

This suggests the present seepage shown in figure 6 is a mixture 

of several seeps from remnant drift openings that have been 

covered over with fill or have collapsed. Mine drainage from 

this seepage cascades over deposits of solid iron precipitate 

before entering Bear Creek.

The Lykens-Williamstown Mine Pool is also drained by 

Big Lick Tunnel, which extends under Big Lick Mountain and 

Bear Valley (figs. 2 and 3). Big Lick Tunnel discharges to 

Wiconisco Creek upstream of Bear Creek and was not sampled 

directly during this study because its source is outside of the 

Bear Creek watershed (fig. 1). However, because it drains the 

same mine pool that contributes drainage to Bear Creek, Big 

Lick Tunnel reduces mine drainage to Bear Creek and increases 

flow and mine-related contaminants measured at WC-UBC. 

Figure 4. Mine drainage discharging from the Lykens Water-Level Tunnel (LWLT) in Bear Creek 

watershed, Dauphin County, Pennsylvania. Picture taken looking toward the source of the mine 

drainage. The survey rod on the right is intended for scale and extends 8 ft above the ground surface. 

See figure 1 for the location of LWLT.

December 20, 2003
Introduction 9

Figure 5. Mine drainage discharging from the Lykens Drift (LD) discharge in Bear Creek watershed, 

Dauphin County, Pennsylvania. Picture taken looking toward the source of the mine drainage. The 

survey rod near the center is intended for scale and extends 4 ft above the water surface. 

December 20, 2003

Figure 6. Mine drainage from several seeps adjacent to the Lykens Drift discharge in Bear Creek 

watershed, Dauphin County, Pennsylvania. Picture taken looking at the confluence of the seeps 

and Bear Creek. The survey rod on the right is intended for scale and extends 7 ft above the 

boulder. 

December 20, 2003
10 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Previous Investigations of Mine Drainage in Bear 

Creek Watershed

The long history of anthracite coal mining has led to many 

detailed studies of regional geology, hydrology, and miningrelated contamination. Many of these studies include information on Bear Creek watershed although Bear Creek itself has 

been the sole focus of only two studies (Skelly and Loy, Inc., 

2003; Susquehanna River Basin Commission, 2001). The collective information garnered from each of the following reports 

assists in understanding the watershed today.

Ash and others (1949) present data on location, altitude, 

and water volume of the Lykens-Williamstown Mine Pool. The 

location of the Lykens-Williamstown Mine Pool published in 

Ash and others (1949) is superimposed onto the study location 

map in figure 1. Ash and others (1949) reported that the 

Lykens-Williamstown Mine Pool surface altitude was 897 ft 

(NGVD 29) and that storage volume was 980 million ft3

(7.33 bgal) of water. 

Several investigations have documented mine drainage in 

Bear Creek. Sanders and Thomas, Inc. (1973) identified six separate sources of mine discharge throughout Bear Creek watershed, characterized the water quality of each, and suggested 

remedial alternatives to mitigate water-quality degradation. 

Some of the sources identified by Sanders and Thomas, Inc. 

(1973) are probably ephemeral and were not flowing during this 

study. Others may have become diffuse zones of seepage due to 

the collapse of earth or man-made barriers that once separated 

them.

Growitz and others (1985) and Wood (1996) published 

water-quality data from the LWLT and LD as part of an assessment of mine drainage in the Anthracite Coal Region. Additional data for flow, major cations and anions, metals, and other 

constituents were collected by PaDEP at site LWLT beginning 

in April 1997 and are available through the World Wide Web 

(U.S. Geological Survey, 2005). Stoe (1998) assessed the water 

quality and aquatic macroinvertebrate community of Bear 

Creek and found that no macroinvertebrates were present 

because of poor water quality. 

More recent investigations have utilized data collected 

during this investigation and data of previous studies. Hedin 

Environmental (1998, 2001) presented designs of aerobic wetlands to passively treat discharges from LWLT and LD. The 

Susquehanna River Basin Commission (SRBC) (2001) determined the TMDLs of selected constituents that should not be 

exceeded to return Bear Creek to a cold-water fishery. A water 

budget completed in 2002 (Skelly and Loy, Inc., 2003) determined the amount of surface runoff entering mine-subsidence 

features. Skelly and Loy, Inc., (2003) also assessed the feasibility of various remediation alternatives for Bear Creek and concluded that the best alternative for removal of iron from drainage at sites LWLT and LD was passive treatment with aerobic 

ponds. 

Study Design and Methods 

This study design provides the chemical and hydrologic 

data necessary to determine the effects of historical coal mining 

and drainage from abandoned mines on Bear Creek and its 

receiving waters, Wiconisco Creek. The effects of historical 

coal mining on streamflow were evaluated on the basis of 

streamflow loss in Bear Creek under low-flow and high-flow 

conditions. The effects of drainage from abandoned mines were 

evaluated on the basis of differences in selected constituents 

between sites. A two-sided Wilcoxon signed-rank test (Helsel 

and Hirsch, 2002) was used to determine significant differences 

between sites within three matched pairs (BC-UMD compared 

to BC-DMD, BC-DMD compared to BCM, and WC-UBC 

compared to WC-DBC) (table 2). A two-sided Wilcoxon ranksum test (Helsel and Hirsch, 2002) was used to determine significant differences between sites LWLT and LD. This test was 

chosen over the Wilcoxon signed-rank test because LWLT and 

LD are considered independent and therefore pairing is not 

appropriate. The null hypothesis for both tests is that there is no 

difference between median values of compared sites. For this 

study, the null hypothesis is rejected if the p-value (probability 

that a difference occurs by chance) is less than 0.05. 

Hydrologic and chemical data were collected by USGS at 

nine sites in the Bear Creek watershed and two sites on Wiconisco Creek (table 2) to characterize flow and chemistry at the 

following locations: (1) the headwaters of Bear Creek (sites 

BCH-A, BCH-B, BCH-C, BCH-D); (2) Bear Creek upstream of 

mine drainage (BC-UMD); (3) at the largest mine discharges 

(sites LWLT and LD); (4) Bear Creek immediately downstream 

of mine discharges (site BC-DMD); (5) at the mouth of Bear 

Creek (site BCM); and (6) Wiconisco Creek upstream and 

downstream of Bear Creek (sites WC-UBC and WC-DBC, 

respectively) (fig. 1). Sites BCH-A, BCH-B, BCH-C, and 

BCH-D were monitored once during high streamflow and once 

during low streamflow for the specific purpose of quantifying 

streamwater losses to the underground mine pool. Chemically, 

sites BCH-A, BCH-B, BCH-C, and BCH-D) are very similar to 

one another and to site BC-UMD. Because more data were collected at site BC-UMD and it is representative of the chemistry 

observed at the four headwater sites, statistical summaries of 

chemical data collected at the headwater sites are not included 

in this report. At sites BC-UMD, LWLT, LD, and BC-DMD, 

instantaneous flow and chemistry data were collected intermittently by USGS from March 1999 to September 1999, then 

monthly from October 1999 to December 2002. Measurements 

of instantaneous flow and chemistry at site LWLT were made 

monthly from March 1999 to August 1999 by PaDEP. Instantaneous flow and chemistry at site BCM was measured monthly 

from October 1999 to December 2002. Site BCM represents the 

integration of all mine discharges and unpolluted flow from 

upstream prior to mixing with Wiconisco Creek. The Wiconisco Creek sites were established 50 ft upstream (WC-UBC) 

and 200 ft downstream (WC-DBC) of Bear Creek and were 
Study Design and Methods 11

monitored monthly from July 2001 to December 2002 to characterize changes in the flow and chemistry after mixing with 

Bear Creek.

Determination of flow rate was used to assess hydrologic 

losses at or inputs to each site. Streamwater loss was quantified 

by synoptic measurements of instantaneous flow rate at BCH-A 

and all downstream sites on Bear Creek on two occasions, under 

sustained high-flow conditions (March 2001) and sustained 

low-flow conditions (August 2001). A continuous record of 

streamflow was computed at BC-DMD from March 1999 to 

December 2002. Because site BC-DMD is immediately downstream of mine inputs, calculation of the proportion of flow 

from upstream sources is possible. The continuous record of 

streamflow at BC-DMD was computed on the basis of water 

levels (stage) recorded every 15-minutes with a pressure transducer. Instantaneous flow-rate computations were made over a 

range of stages to develop an empirical stage-discharge relation 

following Rantz and others (1982a, 1982b). The stage-discharge relation and continuous measurements of water level 

were used to compute a continuous record of flow rate at 

BC-DMD.

Instantaneous flow at BC-UMD, LWLT, LD, BC-DMD, 

BCM, WC-UBC, and WC-DBC was determined by one of three 

methods: (1) from streamflow velocity measurements conducted with a vertical-axis current meter following standard 

methods (Rantz and others, 1982a); (2) by difference; or (3) by 

stage-discharge relations developed at BC-UMD, LWLT, LD, 

BC-DMD, and BCM following Rantz and others (1982a, 

1982b). 

Precipitation in the Bear Creek watershed was estimated 

from two nearby gages, one at DeHart Reservoir Dam and one 

at Harrisburg International Airport (HIA) (Northeast Regional 

Climate Center, 2003). DeHart Reservoir Dam is approximately 

8.5 mi south-southwest of Bear Creek and HIA is approximately 26 mi south-southwest of Bear Creek. The DeHart gage 

began operating in June 1999; the HIA gage has 55 years of 

record. Because of the length of record at the HIA gage, it is 

used to provide a historical context for precipitation measured 

at DeHart Reservoir Dam.

Water-chemistry samples were collected manually as grab 

samples from well-mixed zones in the stream following Ward 

and Harr (1990). Although iron, manganese, and aluminum are 

the principal metal pollutants in Bear Creek, sodium also was 

determined because it is transported conservatively and can be 

helpful to distinguish the chemical signature of each site. Samples analyzed for metals and sulfate were collected in 125-mL 

acid-rinsed polyethylene bottles. Water analyzed for dissolved 

metals and sulfate was forced through a membrane filter with 

0.45-μm pores using a syringe plunger prior to acidification. 

Nitric acid was used to preserve samples analyzed for metals 

and sulfate, except for Fe2+ samples, which were preserved with 

hydrochloric acid. Water analyzed for ANC and acidity was 

unfiltered and was collected in non-acidified 500-mL polyethylene bottles. All samples were stored at approximately 4°C 

during transport and shipping. 

Table 2. Sampling sites in the Bear Creek and Wiconisco Creek watersheds, Dauphin County, Pennsylvania. 

[mi2, square miles; ft, feet; --, not determined]

U.S. Geological 

Survey station 

identification 

number1

Description Acronym

Drainage 

area 

(mi2

)

Altitude2

(ft) Latitude 3 Longitude 3 

01555527 Wiconisco Creek upstream of Bear Creek WC-UBC 28.8 670 40°34′10′′ 76°41′55′′

01555532 Bear Creek at headwaters - A BCH-A 2.20 1,210 40°35′38′′ 76°40′01′′

01555534 Bear Creek at headwaters - B BCH-B 2.98 1,200 40°35′25′′ 76°40′59′′

01555535 Bear Creek at headwaters - C BCH-C 3.16 1,190 40°35′19′′ 76°41′14′′

01555536 Bear Creek at headwaters - D BCH-D 3.64 1,010 40°35′07′′ 76°41′53′′

01555537 Bear Creek upstream of mine drainage BC-UMD 4.27 970 40°35′04′′ 76°41′59′′

01555539 Bear Creek downstream of mine drainage BC-DMD 4.44 820 40°34′46′′ 76°41′59′′

01555540 Bear Creek at mouth BCM 4.70 675 40°34′11′′ 76°41′55′′

01555541 Wiconisco Creek downstream of Bear Creek WC-DBC 33.9 670 40°34′11′′ 76°42′01′′

403448076420001 Lykens Drift LD -- 880 40°34′50′′ 76°41′60′′

403504076415901 Lykens Water-Level Tunnel LWLT -- 980 40°35′06′′ 76°41′59′′

1 U.S. Geological Survey station identification number is assigned based on watershed position for surface-water sites or latitude and longitude for 

mine-drainage sites. U.S. Geological Survey station identification number can be used to cross-reference this report with U.S. Geological Survey Annual 

Water-Data Reports published by Durlin and Schaffstall (2001, 2002, 2003). Data are available via the World Wide Web at http://pa.waterdata.usgs.gov/

nwis/.

2 Altitude was determined from the Lykens, Pennsylvania, 7.5-minute topographic quadrangle published by the U.S. Geological Survey. Vertical 

datum is National Geodetic Vertical Datum of 1929. Accuracy is ± 10 ft.

3 Horizontal datum is North American Datum of 1983. Coordinates previously published in Durlin and Schaffstall (2001, 2002, 2003) may differ 

slightly because they are referenced to the North American Datum of 1927.
12 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Field measurements of pH, specific conductance, dissolved oxygen, temperature, reduction-oxidation potential (Eh), 

and turbidity were made with a calibrated Yellow Springs 

Instruments (YSI) multi-parameter sonde following Wilde and 

others (1998). Each meter was calibrated prior to use according 

to the manufacturers specifications. Ferrous iron was analyzed 

colorimetrically following methods described in HACH Company (2003) at the USGS Pennsylvania District Laboratory in 

New Cumberland, Pa.

Samples collected at all sites between October 1999 and 

December 1999 and duplicates collected in July 2002 were analyzed by the USGS National Water-Quality Laboratory 

(NWQL). The NWQL determined concentrations of total 

sodium, dissolved sulfate, total aluminum, total and dissolved 

iron, and total and dissolved manganese. Total metals concentrations include the suspended fraction (such as suspended 

Fe(OH)3 (s)). Hence, the difference between total and dissolved 

concentrations represents the concentration suspended in the 

water column. Unfiltered samples were analyzed for total metals concentrations by inductively coupled plasma (ICP) spectrometry following Garbarino and Struzeski (1998). Dissolved 

sulfate was analyzed following Fishman and Friedman (1989). 

Analyses of filtered samples for dissolved metals was conducted by ICP spectrometry following Fishman (1993). 

Samples collected at site LWLT between March and 

August 1999 and at all sites from January 2000 through December 2002 were analyzed by the PaDEP laboratory, except for 

duplicates sent to NWQL in July 2002. In addition to the constituents listed above, the PaDEP laboratory also determined the 

concentration of ANC, acidity, and total dissolved residue. 

ANC and acidity were determined by titration to a fixed 

endpoint following standard methods described in Greenburg 

and others (1981). Water analyzed for ANC was titrated to a 

fixed endpoint pH of 3.7. Note that reported ANC values determined following Greenburg and others (1981) may be higher 

than ANC determined by more recently reported standard methods (Clesceri and others, 1998) that require titration to a fixed 

endpoint pH of 4.5. For acidity determination, Greenburg and 

others (1981) require samples with hydrolyzable metal ions 

such as mine drainage to be treated with peroxide and boiled to 

promote oxidation of metal ions and hasten hydrolysis. Note 

that for samples with pH ≥ 6.5, PaDEP did not titrate the sample 

and reported acidity values of zero. This deviation from Greenburg and others (1981) limits acidity reporting to positive or 

zero values only.

Net ANC was calculated as ANC minus acidity as determined by PaDEP laboratory. Cravotta and Kirby (2004a) state 

that net ANC calculated in this manner may underestimate the 

alkalinity requirement to treat net acidic mine water and may 

lead to the incorrect identification of treatment alternatives and 

(or) inadequate treatment. Kirby (2002) and Cravotta and Kirby 

(2004a) suggest that acidity as determined by PaDEP laboratory 

should be interpreted as net acidity. To investigate the applicability of this interpretation to the mine discharges and streamwater of Bear Creek, net acidity was computed as 

Aciditycalculated minus ANC. Aciditycalculated was computed 

from pH and dissolved metals concentration in milligrams per 

liter as 

Aciditycalculated(mg/L as CaCO3) = 50.[10(3-pH) + 2.CFe/55.85 

+ 2.CMn/54.94 + 3.CAl/26.98] (6)

where 

C is concentration of constituent, in milligrams per liter. 

For the computation of net acidity (Aciditycalculated minus 

ANC), it is assumed that ANC was determined by titration to an 

endpoint pH of 4.5. Because PaDEP determined ANC by titration to an endpoint pH of 3.7, this assumption is violated and 

ANC values are higher than those that would be reported if samples were titrated to an endpoint pH of 4.5. This “over-reporting” is not significant for near-neutral samples with high ANC 

but for samples with pH near 4.5, the sign of net acidity may be 

negative (indicating an alkaline condition) when it should actually be positive (indicating an acidic condition) or zero. 

In general, there was disagreement between net acidity and 

acidity reported by PaDEP at site BC-UMD. Net acidity commonly indicated an alkaline condition (the sign was negative) 

when acidity as reported by PaDEP indicated an acidic condition (acidity reported by PaDEP was positive and greater than 

ANC). This is because of relatively low pH (median = 4.6) and 

consequent “over-reporting” of ANC at site BC-UMD. At the 

mine discharges and downstream sites, the magnitude of net 

acidity and acidity determined by PaDEP was different but both 

consistently predicted the same condition (either alkaline or 

acidic). Hence, the net acidity and acidity determined by PaDEP 

have the same interpretation at sites where treatment is a consideration. Therefore, for this report, acidity as determined by 

PaDEP is reported instead of Aciditycalculated. 

Concentrations of total and dissolved metals were determined by ICP spectrometry following the U.S. Environmental 

Protection Agency (1994). Sulfate concentration was determined colorimetrically following the U.S. Environmental Protection Agency National Exposure Research Laboratory 

(1993). Total residue concentration was determined gravimetrically at the PaDEP laboratory by collection of suspended solids 

on a glass filter and drying of insoluble residue at 105°C (Fishman and Friedman, 1989). 

Duplicate samples were collected on July 18, 2002. Each 

set of samples was analyzed separately for selected constituents 

by the PaDEP laboratory and by the NWQL. The results are 

shown in table 3. 

The percent difference between laboratories varies by constituent and site. This could be because of differing methods of 

analyses, interferences at some sites, or lack of sensitivity over 

the range of observed concentrations. Dissolved and total manganese had the lowest range of percent differences (-9 to 

9 percent); dissolved and total iron had the largest range of percent differences (-17 to 41 percent) (table 3). The PaDEP laboratory consistently reported higher values of iron and manganese at all sites except BC-UMD. This indicates that concentrations and calculated loads presented in this report may be 

slightly high.
Study Design and Methods 13

Absolute percent differences were largest in samples from 

site BC-UMD for all constituents except total manganese. 

Water at site BC-UMD has low concentrations of the selected 

constituents (table 3) compared to downstream sites. Lack of 

sensitivity at low concentration may be part of the reason for 

large absolute percent differences at this site. However, laboratory values from analyses of water from site WC-UBC (which 

has lower concentrations than site BC-UMD for most constituents) do not consistently display the same divergence in 

reported values. This suggests that other factors, perhaps interferences, influence the laboratory results from site BC-UMD. 

Regardless of the reason for large percent differences in concentrations reported for site BC-UMD, high percent difference 

at low concentration has less effect and is therefore more tolerable than large percent differences at high concentration. 

Table 3. Comparison of selected constituents in duplicate samples analyzed separately by the Pennsylvania Department of Environmental Protection Laboratory and the U.S. Geological Survey National Water-Quality Laboratory. 

[Locations of sites shown on figure 1; mg/L, milligrams per liter; μg/L micrograms per liter; USGS, U.S. Geological Survey; PaDEP, Pennsylvania Department 

of Environmental Protection; <, less than; --, not determined. Samples collected July 18, 2002.]

Analyzing agency and 

percent difference

Sodium,

(mg/L)1

Sulfate, 

dissolved 

(mg/L)

Aluminum, 

total 

(μg/L)

Iron, 

dissolved

(μg/L)

Iron,

total

(μg/L)

Manganese, 

dissolved

(μg/L)

Manganese, 

total

(μg/L)

Wiconisco Creek upstream of Bear Creek (WC-UBC)

PaDEP 9.2 64.5 <200 70 720 350 370

USGS 8.6 67.8 120 80 650 330 340

Percent difference -7 5 -- 13 -11 -6 -9

Bear Creek upstream of mine drainage (BC-UMD)

PaDEP .8 22.0 <200 4,180 3,160 500 560

USGS .6 18.2 70 4,660 5,390 550 590

Percent difference -33 -21 -- 10 41 9 5

Lykens Water-Level Tunnel (LWLT)

PaDEP .8 69.5 300 5,960 11,500 990 1,010

USGS .7 71.3 280 5,420 10,200 910 930

Percent difference -14 3 -7 -10 -13 -9 -9

Lykens Drift (LD)

PaDEP 6.3 61.3 <200 18,300 18,900 2,120 2,190

USGS 6.0 60.5 <30 16,500 16,400 2,030 2,060

Percent difference -5 -1 -- -11 -15 -4 -6

Bear Creek downstream of mine drainage (BC-DMD)

PaDEP 4.6 59.6 <200 12,600 14,500 1,830 1,880

USGS 4.5 62.1 40 11,800 13,100 1,750 1,790

Percent difference -2 4 -- -7 -11 -5 -5

Bear Creek at mouth (BCM)

PaDEP 5.5 61.2 <200 540 12,500 1,710 1,850

USGS 5.3 63.1 40 560 11,200 1,630 1,730

Percent difference -4 3 -- 4 -12 -5 -7

Wiconisco Creek downstream of Bear Creek (WC-DBC)

PaDEP 7.3 60.5 <200 210 4,950 860 920

USGS 7.0 65.3 80 180 4,690 820 860

Percent difference -4 7 -- -17 -6 -5 -7

1 Dissolved sodium is assumed to equal total sodium. Pennsylvania Department of Environmental Protection analyzed for total sodium. U.S. Geological Survey National Water-Quality Laboratory analyzed for dissolved sodium. 
14 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Effects of Historical Coal Mining on 

Streamflow

Disturbance of surface and underground strata from a century of anthracite coal mining has altered the quantity and variability of streamflow in Bear Creek. Mining on and close to the 

erosional surface of the watershed has left large areas of unconsolidated spoil and fractures that collectively promote infiltration of surface precipitation and streamwater into the underground mine workings. Deep mining and drift techniques have 

created a circuitous maze of flooded voids that extends the 

underground area contributing water to Bear Creek well outside 

the surface watershed (fig. 1). The extent of the underground 

area draining to Bear Creek depends on the degree of interconnectedness of the Lykens-Williamstown Mine with adjacent 

mines (fig. 1). 

Streamflow in Bear Creek originates from precipitation 

runoff, ground water, and drainage from abandoned mines. 

These sources are not mutually exclusive. Precipitation runoff 

or ground water may enter the stream, infiltrate through fractures in the streambed to the underlying mine pool, and overflow as mine drainage to Bear Creek from mine openings, fractures, or other discharge points lower in the watershed. 

Complex interactions between precipitation, streamwater, and 

mine water control streamflow in Bear Creek.

The precipitation record from DeHart Reservoir Dam, 

approximately 8.5 mi southwest of Bear Creek, indicated 

hydrologic conditions during the study period ranged from 

drought to above-average precipitation (fig. 7). Total precipitation at DeHart Reservoir Dam was 29 in. from June 1, 1999, to 

December 31, 1999; 51.2 in. in 2000; 33.02 in. in 2001; and 

43.9 in. in 2002. Average annual precipitation based on 55 years 

of record at HIA is 40 in. (Northeast Regional Climate Center, 

2003). Above-average precipitation fell in 2000 (fig. 7); 

drought conditions dominated in 2001, and 2002 was near average. The maximum monthly rainfall was in September 1999 as 

a result of three intense storm events from September 6-8 

(5.3 in.), September15-17 (4.16 in.), and September 28-30 

(3.26 in.). 

MAMJ J A SO ND J F MAMJ J A SO ND J FMAMJ J A SO ND J FMAMJ J A SO ND

0

20

40

60

80

100

120

1999 2000 2001 2002

0

2

4

6

8

10

12

14

16

18

20

MONTHLY PRECIPITATION

DAILY MEAN STREAMFLOW AT BC-DMD 

INSTANTANEOUS STREAMFLOW AT BC-UMD

PRECIPITATION, IN INCHES

STREAMFLOW, IN CUBIC FEET PER SECOND

Figure 7. Streamflow hydrograph for Bear Creek downstream of mine inputs (BC-DMD) superimposed on instantaneous 

streamflow measurements upstream of mine inputs (BC-UMD), and precipitation measured approximately 8.5 miles 

southwest of Bear Creek at DeHart Reservoir Dam. Precipitation data were recorded by Northeast Regional Climate 

Center at Cornell University (Northeast Regional Climate Center, 2003). 

DATE
Effects of Historical Coal Mining on Streamflow 15

Mean streamflow for the period of record (March 1999 

through December 2002) at BC-DMD was 8.4 ft3/s (Durlin and 

Schaffstall, 2003)1. Note that the mean streamflow is the mean 

of daily mean values computed from continuous water-level 

measurements (daily mean values are plotted in fig. 7). The 

mean instantaneous streamflow at BC-DMD was 8.6 ft3/s 

(table 4) and was computed as the mean of all instantaneous 

streamflow measurements. The fact that the mean streamflow 

and the mean of instantaneous measurements are nearly equal 

indicates the range of hydrologic conditions is well represented 

by the instantaneous measurements. 

Streamflow at BC-DMD (fig. 7) represents an integration 

of the collective inputs from unimpacted sources in the headwaters of Bear Creek (measured at site BC-UMD) and drainage 

from the Lykens-Williamstown Mine Pool. Daily mean streamflow ranged from 1.2 ft3

/s on November 21 and 22, 2001, to 

108 ft3/s on December 17, 2000 (fig. 7). Streamflow at 

BC-DMD is perennial, owing to sustained drainage from 

LWLT, LD, and diffuse zones of seepage. When water loss 

upstream of the mine inputs is 100 percent, base flow in Bear 

Creek is entirely drainage from abandoned mines.

The general trend of the hydrograph at BC-DMD is a seasonal high flow during the winter and early spring months when 

evapotranspiration is least (fig. 7). Superimposed on the high 

seasonal flows are peaks for individual storm events. The mechanisms controlling the high seasonal flows that take place in the 

winter months and the storm peaks in response to precipitation 

are different. The seasonal high flows are controlled by an overall rise in the level of water in the Lykens-Williamstown Mine 

Pool resulting in more flow at sites LWLT and LD. Because of 

its large storage capacity (approximately 980 million ft3; Ash 

and others, 1949), the response of the mine-pool discharge rate, 

measured by drainage discharging from LWLT and LD, lags 

behind the response of streamflow. As a result, the magnitude 

of individual sharp peaks is controlled primarily by storm runoff and is independent of drainage from the mine pool.

Factors controlling the response of Bear Creek to storm 

runoff may include rainfall intensity, evapotranspiration, and 

storage capacity of headwater wetlands. Despite the maximum 

volume of rainfall in September 1999, the maximum daily mean 

streamflow of 108 ft3/s was on December 17, 2000, in response 

to a relatively modest precipitation event totaling 3.16 in. over 

the period December 17-18 (fig. 7). Interception by vegetation, 

evapotranspiration, and excess storage capacity generally are 

less in the winter than in the fall. These factors may explain the 

storm peak of December 2000.

Streamflow measurements made at all sites on March 20, 

2001, and August 7, 2001, indicate that measurable water loss 

occurred between BCH-C and BC-UMD (fig. 1) only during 

the relatively low-flow conditions of August 2001 (mean 

monthly flow of 3.9 ft3

/s at site BC-DMD). Streamflow 

decreased from 0.07 ft3/s at BCH-C to 0.00 ft3/s at BC-UMD. 

Instantaneous flow measurements made during routine sampling trips at BC-UMD during periods of below-normal precipitation concur with this finding. Water loss at BC-UMD was 

commonly 100 percent during the drought conditions of 2001 

(fig. 7). 

The same reach that lost streamwater in August 2001 had 

increasing streamflow in March 2001. Streamflow at BCH-C 

and BC-UMD was 2.4 and 3.0 ft3/s, respectively. This does not 

exclude the possibility that streamwater continued to infiltrate 

over short distances between BCH-C and BC-UMD, even 

though there was a net increase in streamflow over the entire 

reach. 

The streamflow-gaging station at BC-DMD was directly 

downstream of mine inputs; thus, it was a convenient location 

to determine the proportional contribution of each discharge 

from sites LWLT, LD, BC-UMD, and other sources. Under 

base-flow conditions, sites LWLT and LD together contributed 

52 percent of the instantaneous mean flow at BC-DMD; unimpacted surface water from BC-UMD accounted for only 

16 percent and unmeasured inputs were 32 percent (fig. 8A). 

During storm events, water losses upstream of the mine 

drainages were counterbalanced by an increase in surface runoff. As a result, the proportion of streamflow to site BC-DMD 

from site BC-UMD increased to a mean of 47 percent (fig. 8B). 

The proportion of flow from LWLT remained nearly 

unchanged under stormflow conditions (17 percent compared 

to 19 percent), indicating that water volume at LWLT increased 

during storm events. This could be the result of rapid infiltration 

from a surface connection or surface runoff entering between 

the source of the discharge and the sampling point approximately 200 ft downstream. The discharge from LD decreased 

from a mean of 33 percent under base-flow conditions to 

25 percent under stormflow conditions (fig. 8A and B). This 

decrease indicated that flow volume from the site LD did not 

increase in response to precipitation and suggested no strong 

surface connection. Sources listed as “Other” in figure 8 

decreased from 32 percent under base flow to 11 percent under 

stormflow, suggesting a poor surface-water connection. This 

indicates that the “other” category was largely unmeasured 

mine drainage instead of surface runoff.

Increases in flow rate of mine drainage caused by storm 

events is an important consideration for passive treatment. 

Increased transport of iron, the principal pollutant in mine 

drainage entering Bear Creek, can occur in streams that rapidly 

respond to storm events through scour of streambed sediments 

and episodic acidification (Cravotta and Bilger, 2001). Iron and 

trace metals generally are associated with fine streambed sediments (<0.063-mm size particles), those that are most likely to 

be entrained and transported during rapid increases in flow. 

Flow data indicate that resuspension of bed sediment should not 

be a problem at sites LWLT or LD because these sites did not 

exhibit a rapid response to storms. 

1 Streamflow data are published in Durlin and Schaffstall (2001, 2002, 

2003) and are stored in the Automated Data Processing (ADAPS) database of 

the National Water Information System (NWIS) (U.S. Geological Survey, 

2005). 
Table 4. Summary of instantaneous flow data collected at nine sites on Bear Creek and two sites on Wiconisco Creek, Dauphin County, PennsylvaniaDecember 2002. [ft3/s, cubic feet per second; WC-UBC, Wiconisco Creek upstream of Bear Creek; BCH-A, Bear Creek at headwaters - A; BCH-B, Bear Creek at headwaters - B; BCH-C, Bear C

Bear Creek at headwaters - D; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mat mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek; N, number of instantaneous flow determinations; E, estimated; P25, 25th percentile; P75, 75th percentile; %, 

Statistic Flow (ft3/s) WC-UBC BCH-A BCH-B BCH-C BCH-D BC-UMD LWLT LD BC-DMD 

N 17 2 2 2 2 44 49 45 47 Maximum 104 1.0 2.0 2.3 2.4 9.7 3.7 6.1 18 Minimum E 5.80 E .04 .07 .07 E .01 0 .41 .40 3.0 Mean 39 -- -- -- -- 2.0 1.5 2.7 8.6 Median 24 -- -- -- -- .95 1.1 2.6 6.7 Standard deviation 30 -- -- -- -- 2.4 .86 1.3 4.4 P25 19 -- -- -- -- .28 .86 1.7 5.0 P75 56 -- -- -- -- 3.4 1.9 3.0 12 % censored1 1 Censored refers to values preceded by a less-than sign (<). One measurement of instantaneous streamflow at BC-UMD was censored at <0.01 ft3/s. Because the number o

and the population is adequately represented by 44 noncensored measurements, summary statistics were calculated by substituting 0.01 for <0.01. 000002000

% computed2 2 Indicates the percentage of values that were computed either by difference or a rating relating water level to flow (see Study Design and Methods section). Ratings were 

with methods in Rantz and others (1982b). 47 50 0 0 50 41 37 44 13 
Effects of Historical Coal Mining on Streamflow 17

Figure 8. Percent contribution of base flow (A) and stormflow (B) to Bear Creek downstream of mine drainage 

(BC-DMD) computed as the mean ratio of instantaneous flow at sites Bear Creek upstream of mine drainage (BC-UMD), 

Lykens Water-Level Tunnel (LWLT), and Lykens Drift (LD) to instantaneous flow at site BC-DMD. Contribution from 

“Other” sources was computed as the difference between flow at BC-DMD and the sum of BC-UMD + LWLT + LD and 

expressed as a percent of flow at BC-DMD. “Other” sources include unmeasured mine drainage, ground water not 

originating from the Lykens-Williamstown Mine Pool, and surface-water runoff. “N” represents the number of times that 

instantaneous flow was determined for all sites under the specified flow condition. Note that the percent contribution 

from each site was not computed when flow data were unavailable for one or more of the sites. Thus, the number of 

computations in this figure is limited to 44 by site BC-UMD, which had the minimum number of flow determinations 

under any flow condition (38 base-flow determinations + 6 stormflow determinations). Flow data were collected 

between March 1999 and December 2002. 
18 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Effects of Drainage From Abandoned Mines 

on Water Quality

Water discharging from the Lykens-Williamstown Mine 

Pool is the transport medium that conveys the by-products of 

FeS2 oxidation (eqns. 1-5), and dissolution of (Fe, Mn)CO3 and 

aluminosilicate minerals to Bear Creek. Significant by-products 

that alter the water chemistry of Bear Creek include sulfate, 

iron, manganese, and aluminum. ANC (as CaCO3) is also an 

important constituent in mine water entering Bear Creek 

because it buffers protons (H+ ions) produced by hydrolysis 

reactions (eqns. 4 and 5). The principal contributors of abandoned mine drainage to Bear Creek are discharges at sites 

LWLT, LD, and diffuse zones of seepage. This section evaluates the combined effect of these discharges and seeps on the 

water quality of two sites on Bear Creek (BC-DMD and BCM) 

and the two sites on Wiconisco Creek (WC-UBC and 

WC-DBC). 

Processes controlling the hydrology at sites LD and LWLT 

influence the chemistry of each discharge and the downstream 

reach of Bear Creek. Hydrologic and chemical data support at 

least two potential hydrologic processes that are responsible for 

chemical differences between discharges from LD and 

LWLT—(1) different underground flow paths through and residence times within the mine pool, and (2) surface runoff mixing with mine water during storm events.

Oxidation of FeS2 consumes oxygen and increases the 

concentration of iron (eqn. 2). In the presence of organic carbon 

and in the absence of oxygen, Fe(OH)3 reduction will occur in 

favor of sulfate reduction. Under these conditions, sulfate is 

reduced by a bacterially mediated reaction (eqn. 7) that produces hydrogen sulfide (H2S) and ANC in the form of bicarbonate (HCO3

-

) (Drever, 1988). 

SO4

2- + 2 CH2O = H2S + 2 HCO3- (7)

Thus, the anoxic water with relatively high metals and ANC discharged from LD is characteristic of water that has a deep flow 

path through and long residence time within the mine pool. Sulfate reduction and the production of ANC by equation 7 does 

not occur if water has not been in contact with pyrite long 

enough to deplete nearly all dissolved oxygen. Therefore, the 

oxygenated, more acidic condition of water discharged from 

LWLT is characteristic of water that has a relatively short residence time within the mine pool. 

The second process that creates chemical differences 

between LD and LWLT is the surface-water connection at 

LWLT during storm events (fig. 8). Precipitation in the eastern 

United States is more dilute than mine water entering Bear 

Creek (Hem, 1985, p. 35-36). During storm events, mine water 

discharging from LWLT is diluted by surface runoff. As a 

result, some chemical constituents are inversely correlated with 

flow. In contrast, the chemistry of water discharged from site 

LD is not correlated with flow because there is no surface-water 

connection.

Net Acid Neutralizing Capacity (ANC)

ANC is a measure of the capacity of solutes and particulate 

matter in water to neutralize acid. The principal source of ANC 

in mine water is dissolved carbonate, which can be in the form 

of bicarbonate ion (HCO3

-

) or carbonate ion (CO3

2-) (Hedin 

and others, 1994), depending on pH. Dissolved carbonate may 

originate from water in contact with calcite in cementing materials of the Pottsville and Mauch Chunk Formations (Wood and 

others, 1986) and from bacterially mediated sulfate reduction 

(eqn. 7) (Drever, 1988). Bicarbonate is the predominant ionic 

form of carbonate in water with pH ranging from 5 to 8 (Stumm 

and Morgan, 1996); therefore, ANC in mine water entering 

Bear Creek is mainly from bicarbonate. Bicarbonate neutralizes 

free protons by the following reaction:

H+ + HCO3

-

 = H2O + CO2 (8)

Acidity is a measure of the base neutralization capacity of 

water and is primarily from three sources: (1) free protons (the 

concentration of H+), (2) carbonic acid (H2CO3) and organic 

acidity from dissolved organic compounds, and (3) mineral 

acidity from dissolved iron (Fe), manganese (Mn), and aluminum (Al) (Hem, 1985, p. 111). Acidity from free protons 

increases with decreasing pH. Proton acidity in mine drainage 

to Bear Creek is minimal because pH is relatively high (contribution of acidity from free protons calculated using the median 

pH at LWLT is only 0.06 mg/L as CaCO3). Dissolved metals 

contribute to acidity because they can undergo proton (H+ ion) 

producing hydrolysis reactions like the one represented by 

equation 4. Because of elevated metal concentrations, mineral 

acidity is the largest source of acidity to Bear Creek. 

Water can and commonly does contain both ANC and 

acidity. Net ANC was computed as ANC minus acidity as determined by the PaDEP laboratory. Negative values of net ANC 

represent net acidic conditions because there is not enough 

ANC to neutralize acidity. Positive values of net ANC indicate 

net alkaline conditions because there is more than enough ANC 

to neutralize acidity. Net ANC is an important design parameter 

for passive treatment because iron removal is slower in wetlands that receive net acidic mine water (Hedin and others, 

1994).

Bear Creek upstream of mine drainage (BC-UMD) is net 

acidic, with a median net ANC of -9.0 mg/L as CaCO3 (fig.9, 

table 5)2. All sources of acidity at site BC-UMD are not known, 

but contributors may include proton acidity from acidic precipitation, organic acids originating in the headwaters of Bear 

Creek, and dissolved iron and manganese. The water quality at 

this site can be characterized as relatively uninfluenced by mine 

drainage, although dissolved iron and manganese reached maximum concentrations of 7,090 and 850 μg/L, respectively 

2 Water-quality data are published in Durlin and Schaffstall (2001, 2002, 

2003) and are stored in the Water Quality (QWDATA) database of the National 

Water Information System (NWIS) (U.S. Geological Survey, 2005).
Effects of Drainage From Abandoned Mines on Water Quality 19

Figure 9. Ranges of net acid neutralizing capacity measured at seven sites in the Bear Creek study area, Dauphin County, 

Pennsylvania, from March 1999 to December 2002. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens 

Water-Level Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; 

WC-DBC, Wiconisco Creek downstream of Bear Creek]

WC-UBC LWLT LD BC-DMD BCM WC-DBC BC-UMD

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the

(10) Sample size

Outlier - point that is 1.5 to 

Far outlier - point that is greater than 

EXPLANATION

3 times greater than the interquartile

three times the interquartile range

 interquartile range or largest value, 

25th percentile minus 1.5 times the 

interquartile range or the smallest value, 

Mean

whichever is smaller.

whichever is smaller

range

SAMPLING SITE

-75

-50

-25

0

25

50

75

100

125

150

(17)

(37)

(41)

(38)

(37) (37)

(17)

NET ACID NEUTRALIZING CAPACITY, IN MILLIGRAMS PER LITER AS CaCO3
Table 5. Summary statistics for water-quality data collected at nine sites on Bear Creek and two sites on Wiconisco Creek, Dauphin County, Pennsylva

to December 2002. [Locations of sites shown on figure 1; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; ANC, acid neutralizing capacity; NTU, nephelometric 

per liter; N, number of measurements; Max, maximum; Min, minimum; Stnd dev, standard deviation; P25, 25th percentile; P75, 75th percentile; %, percent; <, less than; >, greate

≥, greater than or equal to; -- not determined] Statistic Oxygen, dis- solved (mg/L) Field pH (stan- dard units) Specific conduc- tance (μS/cm) Temper- ature (°C) Sodium, total (mg/L) Acidity, heated, (mg/L as CaCO3)1 Eh (milli- volts) ANC, (mg/L as CaCO3)2 Net ANC, (mg/L as CaCO3)3 Sulfate, dis- solved (mg/L) Residue, total sus- pended (mg/L) Turbid- ity (NTU) Alumi- num, total (μg/L) Iron, dis- solved (μg/L) Iro

ferro

fie

(μg/

Wiconisco Creek upstream of Bear Creek (WC-UBC) N 18 18 18 18 18 18 -- 17 17 18 18 -- 18 18 1

Max 11.6 7.1 267 21.6 18.8 52 -- 30 26 73.8 92 -- 1,600 170 50

Min 6.1 6.2 111 1.6 4.9 .0 -- 13 -39 21.9 <2 -- <200 70 <50Mean 7.8 6.7 188 12.5 8.2 14 -- 20 6 47.7 -- -- -- 110 -- 

Median 7.5 6.7 195 13.4 7.5 .0 -- 20 18 46.1 16 -- 200 100 <50

Stnd dev 1.6 .3 51 6.8 3.3 18 -- 5.0 22 15.2 -- -- -- 31 -- 

P25 6.7 6.6 137 6.2 6.0 .0 -- 16 -16 35.9 4 -- <200 90 <50

P75 8.8 7.0 229 19.1 9.5 32 -- 24 22 60.2 27 -- 650 130 <50% censored4 0 0 0 0 0 0 -- 0 0 0 17 -- 42 0 8

Bear Creek upstream of mine drainage (BC-UMD) N 41 43 43 42 39 38 22 37 37 41 38 15 39 42 4

Max 14.6 6.1 98 17.5 ≥1.1 - 10.0 65 654 24 7 32.8 50 5.4 600 7,090 5,00

Min .9 4.3 26 .2 ≤.5 1.4 216 3.0 -57 ≤10.6 <2 .00 <200 <20 <50

Mean 9.4 4.9 46 8.6 -- 26 405 8.5 -18 -- -- 1.3 -- -- -- 

Median 10.0 4.6 40 9.8 .6 24 428 7.0 -9 <20.0 <2 .9 300 410 <50Stnd dev 3.7 .5 17 5.2 -- 19 107 4.1 18 -- -- 1.6 -- -- -- P25 8.6 4.5 36 3.8 <10.0 9.1 374 7.0 -31 <20.0 <2 .00 <200 140 <50P75 12.3 5.2 51 13.1 <10.0 46 458 8.0 -3 <20.0 7 1.7 300 1,120 ≤60

% censored 0 0 0 0 5 0 0 0 0 76 58 0 23 2 7

Lykens Water-Level Tunnel (LWLT) N 42 44 49 43 44 43 22 41 41 46 43 15 44 41 4

Max 11.4 7.0 238 11.0 ≥1.2 - 10.0 74 630 32 26 82.3 224 150 1,000 11,900 6,00

Min 6.5 5.1 96 8.0 .6 .0 243 .0 -74 <20.0 <2 22 <200 910 <50Mean 8.5 5.9 181 10.2 -- 21 352 16 -4 -- -- 92 -- 6,060 -- 

Median 8.5 5.9 179 10.3 .8 7 335 16 9 63.0 12 99 300 5,170 2,10Stnd dev 1.0 .3 26 .5 -- 23 82 6.8 26 -- -- 32 -- 3,000 

P25 8.2 5.8 165 10.0 .7 .0 311 14 -24 53.8 4 86 200 3,620 1,00P75 8.8 6.0 196 10.6 .8 43 358 19 15 73.1 19 110 500 8,860 3,90% censored 0 0 0 0 5 0 0 0 0 4 12 0 18 0 
Lykens Drift (LD)

N 42 44 44 43 39 38 21 38 38 41 38 14 39 42 4Max 5.7 7.1 370 13.4 ≥6.6 - 10.0 .0 354 140 140 105 72 2.3 ≥200 - 500 21,400 19,00

Min .2 6.1 282 11.3 ≤4.4 .0 115 106 106 54.5 <2 .00 <200 15,600 60

Mean .8 6.5 346 13.2 -- .0 180 123 123 68.8 -- .40 -- 18,600 4,30

Median .5 6.5 354 13.3 <10.0 .0 154 123 123 65.8 10 .00 <200 18,300 3,90Stnd dev 1.0 .2 23 .3 -- .0 64 8.4 8 11.0 -- .80 -- 1,200 3,29P25 .3 6.4 337 13.2 <10.0 .0 138 116 116 60.1 6 .00 <200 17,800 2,00P75 .8 6.6 364 13.3 <10.0 .0 187 132 132 76.0 19 .20 <200 19,500 4,80% censored 0 0 0 0 5 0 0 0 0 0 8 0 97 0 

Bear Creek downstream of mine drainage (BC-DMD)

N 43 45 45 44 39 38 22 37 37 41 38 15 39 42 4Max 11.9 7.1 324 14.6 ≥5.2 - 10.0 46 365 92 92 90.9 34 130 ≥400 - 500 14,100 8,80

Min 7.0 6.2 103 6.5 ≤1.9 .0 114 30 2 26.0 <2 8.3 <200 4,060 <50

Mean 9.4 6.8 235 11.3 -- 1.6 209 62 60 55.4 -- 31 -- 10,000 -- 

Median 9.4 6.8 234 11.6 3.2 .0 191 64 64 57.7 20 25 <200 9,970 3,30Stnd dev 1.2 .2 55 2.3 -- 7.8 76 19 22 15.2 -- 29 -- 3,030 -- 

P25 8.6 6.7 198 9.8 2.4 .0 153 42 42 45.6 13 16 <200 7,700 1,20P75 10.2 6.9 285 13.3 3.8 .0 249 78 78 63.0 24 29 200 12,900 4,10% censored 0 0 0 0 5 0 0 0 0 0 5 0 72 0 

Bear Creek at mouth (BCM)

N 41 43 43 42 39 38 22 37 37 41 38 15 39 42 4Max 12.0 7.8 299 17.2 ≥6.5 - 10.0 .0 426 90 90 94.0 94 160 800 4,100 3,20

Min 7.3 6.1 122 6.5 2.4 .0 110 34 34 <20 .0 <2 9.3 <200 30 <50Mean 9.9 7.1 231 11.8 -- .0 222 63 63 -- -- 80 -- 1,580 Median 10.1 7.2 234 11.7 <10.0 .0 194 66 66 59.9 20 89 <200 1,320 <50Stnd dev 1.2 .3 45 2.8 -- .0 79 16 16 -- -- 39 -- 1,190 P25 9.0 7.0 202 9.8 <10.0 .0 169 48 48 49.7 14 59 <200 650 <50P75 10.8 7.4 267 14.4 <10.0 .0 242 76 76 65.9 30 96 <200 2,490 1,30% censored 0 0 0 0 5 0 0 0 0 2 5 0 82 0 5

Table 5. Summary statistics for water-quality data collected at nine sites on Bear Creek and two sites on Wiconisco Creek, Dauphin County, Pennsylva

to December 2002.—Continued

[Locations of sites shown on figure 1; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; ANC, acid neutralizing capacity; NTU, nephelometric 

per liter; N, number of measurements; Max, maximum; Min, minimum; Stnd dev, standard deviation; P25, 25th percentile; P75, 75th percentile; %, percent; <, less than; >, greate

≥, greater than or equal to; -- not determined]

Statistic

Oxygen, 

dissolved 

(mg/L)

 Field 

pH 

(standard 

units)

Specific 

conductance 

(μS/cm)

Temperature 

(°C)

Sodium, 

total

(mg/L)

Acidity, 

heated, 

(mg/L as 

CaCO3)1

Eh

(millivolts)

ANC, 

(mg/L as 

CaCO3)2

Net 

ANC, 

(mg/L 

as 

CaCO3)3

Sulfate, 

dissolved

(mg/L)

Residue, 

total 

suspended

(mg/L)

Turbidity 

(NTU)

Aluminum, 

total

(μg/L)

Iron, 

dissolved

(μg/L)

Iro

ferro

fie

(μg/
Wiconisco Creek downstream of Bear Creek (WC-DBC) N 18 18 18 18 18 18 3 17 17 18 18 -- 18 18 1

Max 11.5 7.3 293 19.8 10.1 49 300 50 50 73.7 182 -- 1,600 680 1,00Min 6.8 6.1 113 2.2 .8 .0 210 16 -33 23.1 <2 -- <200 80 <50Mean 8.3 6.8 202 12.1 6.4 6.1 252 31 25 49.6 -- -- -- 320 Median 7.9 6.9 205 13.3 6.6 .0 245 32 32 51.5 20 -- <200 330 <50Stnd dev 1.2 .4 57 5.8 2.1 14 45 10 22 14.0 -- -- -- 160 

P25 7.6 6.5 148 6.8 5.2 .0 228 22 21 41.6 3 -- <200 220 <50P75 9.1 7.0 249 17.3 7.5 .0 273 36 36 59.6 26 -- 450 360 <50% censored 0 0 0 0 0 0 0 0 0 0 17 -- 50 0 7

1 Acidity, as determined by the Pennsylvania Department of Environmental Protection Laboratory and reported as positive values or zero. If the pH of the sample was 6.5, a 

reported. No negative values were reported. 2 Determined by titration to an endpoint pH of 3.9. 3 Computed as ANC minus acidity as determined by the Pennsylvania Department of Environmental Protection. 4 Censored refers to values preceded by a less-than sign (<). Table 5. Summary statistics for water-quality data collected at nine sites on Bear Creek and two sites on Wiconisco Creek, Dauphin County, Pennsylva

to December 2002.—Continued [Locations of sites shown on figure 1; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; ANC, acid neutralizing capacity; NTU, nephelometric 

per liter; N, number of measurements; Max, maximum; Min, minimum; Stnd dev, standard deviation; P25, 25th percentile; P75, 75th percentile; %, percent; <, less than; >, greate

≥, greater than or equal to; -- not determined] Statistic Oxygen, dis- solved (mg/L) Field pH (stan- dard units) Specific conduc- tance (μS/cm) Temper- ature (°C) Sodium, total (mg/L) Acidity, heated, (mg/L as CaCO3)1 Eh (milli- volts) ANC, (mg/L as CaCO3)2 Net ANC, (mg/L as CaCO3)3 Sulfate, dis- solved (mg/L) Residue, total sus- pended (mg/L) Turbid- ity (NTU) Alumi- num, total (μg/L) Iron, dis- solved (μg/L) Iro

ferro

fie

(μg/
Effects of Drainage From Abandoned Mines on Water Quality 23

(table 5). Concentrations of dissolved iron and manganese 

above the median values (410 and 270 μg/L, respectively) generally were at low flow, when site BC-UMD was dominated by 

stagnant pools. Because dissolved metals concentrations 

increased at low flow, the lowest net ANC also was at low flow 

(fig. 10). 

Net ANC at site LWLT ranged from -74 to 26 mg/L as 

CaCO3; the median was 9 mg/L as CaCO3 (fig. 9). The lowest 

net ANC values were during low flow (fig. 10) and were concurrent with the highest dissolved iron and manganese concentrations. The discharge at site LD was the largest source of ANC 

to Bear Creek with a median of 123 mg/L as CaCO3 (fig. 9) and 

varied little with flow (fig. 10). Net ANC in water from site LD 

was significantly higher than the discharge at site LWLT 

(p-value = <.0001; table 6). Because of the odor of H2S at site 

LD, the source of ANC is probably sulfate reduction (eqn. 7). 

Relatively high ANC and reducing conditions of site LD compared to LWLT suggest that water discharging from site LD has 

a longer residence time in the mine pool than water discharging 

at site LWLT. Mixing of water from LWLT, LD, and diffuse 

seeps with the net acidic waters of BC-UMD resulted in an 

increase in the median net ANC at site BC-DMD to 64 mg/L as 

CaCO3 (fig. 9). Little change in net ANC occurred between 

BC-DMD and BCM (table 6). The overall effect of Bear Creek 

mixing with Wiconisco Creek was an increase in median net 

ANC of 14 mg/L as CaCO3 at site WC-DBC compared to 

WC-UBC (table 5) (p-value = 0.0005; table 6).

Specific Conductance

Specific conductance is a measure of the capacity of dissolved ions in water to conduct an electrical current (Wilde and 

others, 1998). Specific conductance is related to the dissolved 

solids concentration (Hem, 1985, p. 67) and can be used as a 

qualitative measure to distinguish between waters with high and 

low concentrations of dissolved solids. The major ions responsible for elevated specific conductance in Bear Creek are 

SO4

2-, HCO3-

, Fe2+, Fe3+, and Mn2+.

Site BC-UMD had water with low specific conductance 

(fig. 11) because of the relative absence of mine drainage compared to downstream sites. Specific conductance in water at site 

BC-UMD ranged from 26 to 98 μS/cm; the median was 

40 μS/cm (table 5). There was little correlation with flow, 

although the specific conductance values were highest at very 

low flow when dissolved solids were concentrated in stagnant 

pools by evaporation (fig. 12). The range of specific conductance values at site BC-UMD was comparable to nearby 

unmined watersheds that supply water to the town of Lykens 

(Charles McGarrell, Pennsylvania Department of Environmental Protection, oral commun., 2000). 

Median specific conductance of water discharging at 

LWLT was 179 μS/cm (table 5) and decreased as flow 

increased (fig. 12). The relation of decreasing specific conductance with flow was evidence of a connection to unimpacted 

water, either by runoff entering between the LWLT outlet and 

the sampling location 200 ft downstream or precipitation infiltrating into the local underground mine water that drains to site 

LWLT. In contrast, specific conductance of water discharging 

from LD varied little with flow, indicating a poor surface-water 

connection (fig. 12). Median specific conductance of water at 

site LD was 354 μS/cm (table 5), significantly higher than at 

site LWLT (p-value = <0.0001; table 6). Specific conductance 

in water at BC-DMD ranged from 103 to 324 μS/cm; the 

median was 234 μS/cm (table 5), a significant increase compared to BC-UMD (p-value = <0.0001; table 6). As at site 

LWLT, specific conductance decreased at sites BC-DMD and 

BCM as flow increased (fig. 12). This was the result of an 

increase in the proportion of relatively dilute runoff originating 

in the headwaters during storm events (fig. 8). Bear Creek 

increased the median specific conductance at site WC-DBC by 

10 μS/cm compared to site WC-UBC (table 5) (p-value = 

0.0014; table 6). 
Figure 10. Relation of net acid neutralizing capacity to flow at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from M

to December 2002. [WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LDDrift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Cree

EXPLANATION ACIDIC ALKALINE -80 -400 4080 120 150 0 100 125 0 4 8 12 0 5 10 15 20 0 1 2 3 4 0 2

0 1 2 34 5 6 7 0 5 10 15 20 FLOW, IN CUBIC FEET PER SECOND 25 50 75 WC-UBC BC-UMD LWLT LD BC-DMD BCM 

SAMPLING SITE

NET ACID NEUTRALIZING CAPACITY, 

IN MILLIGRAMS PER LITER AS CaCO

3
Effects of Drainage From Abandoned Mines on Water Quality 25

Table 6. Results of statistical analyses performed on four paired sites in the Bear Creek study area, Dauphin County, Pennsylvania.

[Locations of sites shown on figure 1; WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens 

Water-Level Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; mV, millivolts; ANC, acid neutralizing capacity; 

NTU, nephelometric turbidity unit; μg/L micrograms per liter; <, less than; --, not determined]

Constituent

Site

BC-UMD

compared to 

BC-DMD1

LWLT 

compared to 

LD2

BC-DMD 

compared to 

BCM1

WC-UBC

compared to 

WC-DBC1

p-value3 p-value p-value p-value

Dissolved oxygen (mg/L) 0.4683 <0.0001 0.1410 0.0024

pH <.0001 <.0001 <.0001 .7260

Specific conductance (μS/cm) <.0001 <.0001 .9277 .0014

Temperature (°C) .0075 <.0001 .3498 .2481

Sodium, total (mg/L) <.0001 <.0001 .0004 .0002

“Hot” Acidity (mg/L as CaCO3) <.0001 <.0001 .1640 .0094

Eh (mV) <.0001 <.0001 .6685 --

ANC (mg/L as CaCO3) <.0001 <.0001 .9375 .0005

Net ANC (mg/L as CaCO3) <.0001 <.0001 .8445 .0005

Sulfate (mg/L) .0039 .1673 .4366 .1840

Residue, total (mg/L) .0125 .9161 .5527 .3249

Turbidity (NTU) .0002 <.0001 .0186 --

Aluminum, total (μg/L) -- -- -- --

Iron, dissolved (μg/L) <.0001 <.0001 <.0001 .0006

Iron, ferrous (μg/L) -- -- -- --

Iron, total (μg/L) <.0001 <.0001 .2807 <.0001

Manganese, dissolved (μg/L) <.0001 <.0001 .2610 .0002

Manganese, total (μg/L) <.0001 <.0001 .8374 .0003

1 Results of two-sided Wilcoxon signed-rank test.

2 Results of two-sided Wilcoxon rank-sum test.

3 For this study, the null hypothesis is rejected if the p-value is less than 0.05. 
26 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002 SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

 WC- BC- LWLT LD BC- BCM WCUBC UMD DBC DMD

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the

(18) Sample size

Outlier - point that is 1.5 to 

EXPLANATION

3 times greater than the interquartile range

interquartile range or largest value, 

25th percentile minus 1.5 times the 

interquartile range or the smallest value, 

Mean

SAMPLING SITE

whichever is smaller

whichever is smaller

Figure 11. Ranges of specific conductance measured at seven sites in the Bear Creek study area, Dauphin County, 

Pennsylvania, from March 1999 to December 2002. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens WaterLevel Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, 

Wiconisco Creek downstream of Bear Creek]

0

50

100

150

200

250

300

350

400

(18)

(43)

(49)

(44)

(45)

(43) (18)
Figure 12. Relation of specific conductance to flow at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from March 1999 t

2002. [WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LD, LyBC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

0 100 125 0 4 8 12 0 5 10 15 20 0 1 2 3 4 0 25 5

0 1 2 34 5 6 7 0 5 10 15 20

WC-UBC BC-UMD LWLT LD BC-DMD BCM W

FLOW, IN CUBIC FEET PER SECOND 

SAMPLING SITE

0

50

100150200250300350400

25 50 75
28 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Dissolved Oxygen 

Dissolved oxygen is an important constituent for the 

removal of iron because it is the oxidizing agent in the hydrolysis reactions that produce solid iron precipitates, nominally 

Fe(OH)3 (eqn. 4). The solubility of oxygen in water is limited 

by and is directly proportional to its partial pressure in air and 

water temperature. The water discharging from LWLT differed 

from water discharging from LD with respect to oxygen concentration; thus, treatment approaches for iron removal will 

need to consider these differences. 

Streamwater at BC-UMD was aerobic except when 

streamflow was <0.01ft3/s. Median dissolved oxygen concentration over the range of measured flows was 10.0 mg/L 

(fig. 13, table 5). When flow was <0.01ft3/s, median dissolved 

oxygen concentration was only 2.3 mg/L, reaching a minimum 

of 0.9 mg/L (fig. 14). This could have been a result of biological 

oxygen demand from organic matter that was not transported 

because of stagnant flow. Higher concentration of metals at low 

flow also may contribute to oxygen depletion because oxygen 

is necessary for hydrolysis of dissolved metals.

The discharge from LWLT was aerobic over the entire 

range of flow conditions; the median dissolved oxygen concentration was 8.5 mg/L (table 5). In contrast, LD was nearly 

anoxic (figs. 13 and 14); the median dissolved oxygen concentration was 0.5 mg/L (table 5). The odor of hydrogen sulfide gas 

(H2S) emanated from water discharged at LD providing evidence that pyrite oxidation (eqn. 1) had consumed nearly all 

oxygen and sulfate reduction (eqn. 7) was occurring. Although 

water draining from LD was anoxic at the point of discharge, 

oxygenation occurred quickly. Dissolved oxygen concentration 

was nearly 75 percent saturation only 50 ft downstream of the 

source (Jeffrey Chaplin, U.S. Geological Survey, 2000, unpub. 

data). This was a result of exposure to air that was facilitated by 

turbulent flow over the steep gradient between site LD and its 

confluence with Bear Creek (a decrease in elevation of approximately 20 ft over a horizontal distance of 100 ft). Despite rapid 

oxygenation, oxidation of iron was incomplete. 

As a result of oxygenation between site LD and Bear 

Creek, dissolved oxygen at site BC-DMD remained relatively 

high; the median was 9.4 mg/L (table 5). The range of dissolved 

oxygen concentrations measured at site BC-DMD was smaller 

than at site BC-UMD because inputs from LWLT and LD varied less (fig. 13) and showed no relation to flow (fig. 14). Mine 

drainage did not significantly change dissolved oxygen concentration between sites BC-UMD and BC-DMD (p-value = 

0.4683; table 6). Median dissolved oxygen increased slightly to 

10.1 mg/L at site BCM (table 5), but the increase was not statistically significant (p-value = 0.1410; table 6). The net effect of 

Bear Creek on Wiconisco Creek was an increase in median dissolved oxygen of 0.4 mg/L at site WC-DBC (table 5). Even 

though this increase was statistically significant (p-value = 

0.0024; table 6), it is negligible from a biological or treatment 

perspective. 

pH

The pH of water is the negative log of hydrogen ion concentration and ranges from 6.5 to 8.5 in most natural streams 

(Hem, 1985). Abandoned mine drainage can be acidic (pH<7.0) 

or alkaline (pH>7.0), but pH alone is misleading because of 

mineral acidity in the form of dissolved metals. Water that has 

near-neutral pH and elevated concentrations of dissolved metals 

(particularly dissolved iron) has the potential to become acidic 

after oxidation and hydrolysis of the metals (eqns. 3 and 4, 

respectively). This potential is measured by acidity titration, not 

pH. Hence, acidity is a more useful measurement to characterize the severity of mine drainage (Rose and Cravotta, 1998). 

Nonetheless, pH is an important consideration for iron removal 

because low pH increases the solubility of metal hydroxides and 

negatively influences the rate of the oxidation and hydrolysis 

processes important to iron removal in passive-treatment systems (Hedin and others, 1994). 

Bear Creek is poorly buffered (median net ANC =

-9.0 mg/L as CaCO3; table 5) upstream of the mine discharges 

(BC-UMD) and has a median pH of 4.6 (fig. 15). Because 

buffer capacity is low, pH is subject to change upon the introduction of acidity or alkalinity. Acidity can be derived from 

dilute weakly acidic rainfall that may become more acidic upon 

contact with unconsolidated coal spoil. When storm runoff 

mixed with streamwater above BC-UMD, any ANC was 

quickly depleted and the pH decreased, resulting in the inverse 

correlation between streamflow and pH depicted in figure 16. 

The highest pH values at BC-UMD were measured under very 

low flow conditions (fig. 16) dominated by stagnant pools. 

ANC in water discharged from sites LWLT, LD, and diffuse zones of seepage buffered the net acidic headwaters upon 

mixing. The median pH of site LWLT was 5.9 (table 5) and was 

poorly correlated with flow (fig. 16) despite a connection with 

weakly acidic surface runoff discussed earlier in this report. 

Water discharged from LWLT is commonly net alkaline at high 

flows (fig. 10), indicating that pH is least likely to change when 

mixing with surface runoff is greatest. Water discharging from 

LD was near neutral (median pH = 6.5; fig. 15) and was not correlated with flow (fig. 16). Low variability of pH over the range 

of measured flow conditions at LD (standard deviation = 0.2 pH 

units; table 5) suggests that excess ANC (fig. 9) derived from 

sulfate reduction (eqn. 7) or prolonged contact with carbonate 

cementing media in the Mauch Chunk and Pottsville Formations (figs. 2 and 3) buffers any acidity production. Water discharged from LD buffers and stabilizes the pH at site BC-DMD 

over the range of measured streamflows (fig. 16). However, the 

inverse relation between pH and flow at site BCM (fig. 16) indicates that ANC from LD was not great enough to buffer all 

acidic surface runoff between sites BC-DMD and BCM. 

The chemistry of streamwater at site BC-DMD represents 

a mixture of two main source waters—the weakly acidic headwaters and the comparatively alkaline mine discharges. ANC in 

mine drainage from LD and associated seeps increased
Effects of Drainage From Abandoned Mines on Water Quality 29

 WC- BC- LWLT LD BC- BCM WCUBC UMD DBC DMD

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the interquartile

Sample size

Outlier - point that is 1.5 to 

Far outlier - point that is greater than 

EXPLANATION

3 times greater than the interquartile range

3 times the interquartile range

 range or largest value, whichever is smaller

25th percentile minus 1.5 times the interquartile 

 range or the smallest value, whichever is smaller

Mean

SAMPLING SITE

Figure 13. Ranges of dissolved oxygen measured at seven sites in the Bear Creek study area, Dauphin County, 

Pennsylvania, from March 1999 to December 2002. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; 

LWLT, Lykens Water-Level Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek 

at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]

(18)

0

2

4

6

8

10

12

14

16

(18)

(41)

(42)

(42)

(43) (41)

(18)
Figure 14. Relation of dissolved oxygen to flow at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from March 19

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level TunneBC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

0 50 125 0 4 8 12 0 1 2 3 4 0 2

0 1 2 34 5 6 7 0 5 10 15 20 0 5 10 15 20

WC-UBC BC-UMD LWLT LD BC-DMD BCM 

FLOW, IN CUBIC FEET PER SECOND 

SAMPLING SITE

02468

101214

25 75 100
Effects of Drainage From Abandoned Mines on Water Quality 31

Figure 15. Ranges of pH measured at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from March 1999 

to December 2002. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens WaterLevel Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, 

Wiconisco Creek downstream of Bear Creek] pH, IN STANDARD UNITS

 WC- BC- LWLT LD BC- BCM WCUBC UMD DBC DMD

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the

(10) Sample size

Outlier - point that is 1.5 to 

Far outlier - point that is greater than 

EXPLANATION

3 times greater than the interquartile range

3 times the interquartile range

interquartile range or largest value, 

25th percentile minus 1.5 times the 

interquartile range or the smallest value, 

Mean

SAMPLING SITE

whichever is smaller

whichever is smaller.

4

5

6

7

8

(18)

(43)

(44)

(44) (45)

(43)

(18)
Figure 16. Relation of pH to flow at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from March 1999 to December 2[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LBC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]

pH, IN STANDARD UNITS

0 50 125 0 4 8 12 0 1 2 3 4 0 25 

0 1 2 34 5 6 7 0 5 10 15 20 0 5 10 15 20

WC-UBC BC-UMD LWLT LD BC-DMD BCM W

FLOW, IN CUBIC FEET PER SECOND 

SAMPLING SITE

45678

25 75 100

EXPLANATION

ACIDICALKALINE
Effects of Drainage From Abandoned Mines on Water Quality 33

median pH more than 2 units between sites BC-UMD and

BC-DMD (median pH of 4.6 at BC-UMD compared to 6.8 at 

BC-DMD; p-value = <0.0001). However, the pH of streamwater 

at BC-DMD was not intermediate between the source-water 

components. In fact, the pH at BC-DMD was greater than the 

alkaline mine water discharging from site LD (median pH = 6.8 

at site BC-DMD compared to 6.5 at site LD). Further, a median 

pH of 7.2 in streamwater at site BCM confirms a trend of 

increasing pH downstream of site LD. 

The most likely explanation for this trend is exsolution of 

carbon dioxide (CO2) and H2S from water discharging at site 

LD and associated seeps. Aeration of mine drainage can result 

in rapid saturation with O2, causing the simultaneous production of hydroxyl ions, (OH-

) and consumption of hydrogen ions 

(Cravotta and Kirby, 2004a) through the following reactions 

that represent exsolution of CO2 (eqns. 9 and 10) and H2S 

(eqn. 11) (Stumm and Morgan, 1996): 

HCO3

- = CO2 (g) + OH- (9)

H2CO3* = CO2 (g) + H2O (10)

HS- + H+ = Η2S (aq) → Η2S (g) (11)

[where H2CO3* = dissolved carbon dioxide (CO2 (aq)) + carbonic acid (H2CO3)]. These reactions occur more quickly than 

acid producing hydrolysis (eqn. 4) reactions and therefore commonly cause pH of mine drainage to initially increase (Cravotta 

and Kirby, 2004a). With time, hydrolysis of dissolved metals 

may produce enough acidity to lower pH. This was not observed 

in Bear Creek; pH increased between sites BC-DMD and BCM 

despite acidity production from hydrolysis of dissolved iron.

Several processes counter acidity production and may 

explain the apparent contradiction. First, acidity due to H2CO3* 

declines and pH increases during CO2 exsolution (eqn. 10). 

Secondly, H+ produced by hydrolysis of iron can be consumed 

during reaction with bisulfide ion (HS-) in the formation of 

hydrogen sulfide gas (H2S (g)) (eqn. 11). Lastly, high concentration of ANC from site LD (median ANC concentration = 

123 mg/L as CaCO3) and possibly from the sewage treatment 

plant upstream of BCM buffers acidity and may increase pH.

Iron

Iron is the principal metal pollutant in Bear Creek (Stoe, 

1998; Sanders and Thomas, Inc., 1973; Hedin Environmental, 

2001; Susquehanna River Basin Commission, 2001). Pyrite 

oxidation results in production of Fe2+ and Fe3+ ions (eqns. 2 

and 3). The valence of dissolved iron in water depends on pH 

and Eh. Under the near-neutral condition of water in mineaffected reaches of Bear Creek, the dominant dissolved species 

was expected to be Fe2+ (Stumm and Morgan, 1996). Hydrolysis of Fe3+ forms relatively insoluble Fe(OH)3 (eqn. 4). This 

precipitate is orange in color and is ubiquitous in Bear Creek 

downstream of site BC-UMD. It coats the channel substrate 

rendering the lower reach of Bear Creek unsuitable for aquatic 

life (Stoe, 1998).

Site BC-UMD, which has a median total iron concentration of 550 μg/L, is useful for evaluation of the collective effect 

of iron originating from LWLT, LD, and seeps on downstream 

sites. The differing hydrologic behavior of sites LWLT and LD 

influences the concentration and phase of iron in each discharge. The short residence time of water draining at site LWLT 

relative to site LD results in less iron production and oxygen 

consumption by pyrite oxidation (eqn. 1) and precludes ANC 

production via sulfate reduction (eqn. 7) because anoxia is not 

achieved. As a result, the relatively acidic discharge from 

LWLT has a median total iron concentration that is approximately half that of site LD (10,000 compared to 19,000 μg/L). 

The phase of iron also differs between sites LWLT and 

LD. The difference between median total and dissolved iron 

fractions (4,830 μg/L, fig. 17) in water originating from LWLT 

indicates that much of the iron at this site had hydrolyzed 

(eqn. 4) and was suspended. In contrast, nearly all iron originating from LD was in solution (median dissolved iron = 

18,300 μg/L, median total iron = 19,000 μg/L). After mixing 

with mine drainage from sites LWLT, LD, and diffuse zones of 

seepage, the median total iron concentration at site BC-DMD 

was 12,600 μg/L; a significant increase compared to site 

BC-UMD (p-value = <.0001; table 6). Most iron at BC-DMD 

was dissolved (median dissolved iron concentration = 

9,970 μg/L), indicating that the traveltime between LD and 

BC-DMD was too short to allow significant oxidation and 

hydrolysis of iron to occur. In contrast, most dissolved iron at 

site BCM had hydrolyzed (eqn. 4) and was suspended (fig. 17).

Because water from LD was nearly anoxic, oxidation of 

Fe2+ (eqn. 3) and hydrolysis of Fe3+ (eqn. 4) occurred only after 

oxygen was introduced. Even though deposits of Fe(OH)3

(fig. 5) are evidence that some iron precipitation and settling 

occurred prior to mixing with Bear Creek, most iron did not 

undergo hydrolysis by the time it reached site BC-DMD 

(fig. 17). The conversion of dissolved iron to Fe(OH)3 occurred 

between sites BC-DMD and BCM, decreasing the median concentration of dissolved iron at site BCM to 1,320 μg/L compared to the total iron concentration of 10,600 μg/L (table 5). 

The decrease in median total iron between sites BC-DMD and 

BCM (2,000 μg/L) indicates that approximately 16 percent of 

the iron at site BC-DMD was retained in the stream reach 

between sites BC-DMD and BCM. 

On the basis of the low solubility of Fe3+ (Rose and Cravotta, 1998) and the pH and redox conditions of the mine drainage at site LD, the stable form of iron was expected to be Fe2+

(Stumm and Morgan, 1996). However, ferrous iron was only a 

fraction of the dissolved concentration (median Fe2+ = 

3,900 μg/L, median dissolved = 18,300 μg/L). The near-neutral 

pH (median pH = 6.5) and low oxidation potential (median dissolved oxygen concentration = 0.5 mg/L; median Eh = 154mV) 

indicated this discharge was near the stability boundary 

between Fe2+ and Fe(OH)3 (Rose and Cravotta, 1998). Consequently, there may have been dissolved Fe3+ in solution that 

was rapidly undergoing hydrolysis to Fe(OH)3 (eqn. 4). A sec-
34 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Figure 17. Ranges of dissolved and total iron measured at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from 

March 1999 to December 2002. One value of dissolved iron concentration censored at <20 μg/L and two values of total iron concentration 

censored at <300 μg/L were omitted from the BC-UMD plot. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level 

Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek 

downstream of Bear Creek]

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the interquartile

(18) Sample size

Outlier - point that is 1.5 to 

Far outlier - point that is greater than 

EXPLANATION

3 times greater than the interquartile range

3 times the interquartile range

 range or largest value, whichever is smaller

25th percentile minus 1.5 times the interquartile 

 range or the smallest value, whichever is smaller

Mean

(18)

Dissolved Total 

SAMPLING SITE

DISSOLVED AND TOTAL IRON, IN MICROGRAMS PER LITER

 WC- BC- LWLT LD BC- BCM WCUBC UMD DBC DMD

Pennsylvania Department of Environmental 

Pennsylvania Department of Environmental 

0

2,500

5,000

7,500

10,000

12,500

15,000

17,500

20,000

22,500

25,000

27,500

30,000

32,500

35,000

(18)

(42)

(41)

(42)

(42)

(42)

(18)

(18)

(42)

(46)

(42)

(42)

(42)

(18)

Protection water-quality criterion for total iron 

(daily mean)

Protection water-quality criterion for dissolved

iron (maximum)
Effects of Drainage From Abandoned Mines on Water Quality 35

ond possibility for low Fe2+ concentration compared to dissolved iron is that some aeration of the samples could have 

occurred between collection and analysis. This would cause 

oxidation of Fe2+ to Fe3+, resulting in measured concentrations 

of Fe2+ that were less than actual in-situ concentrations. 

The relation of total and dissolved iron with flow differs at 

sites LWLT, LD, BC-DMD, and BCM (fig. 18). Concentrations 

decreased as flow increased at site LWLT with little change in 

the ratio of dissolved to total iron (fig. 18). The decrease in concentration with respect to flow was consistent with that of specific conductance (fig. 12) and was the result of dilution from 

poorly buffered runoff entering between the source and the 

sampling location or precipitation infiltrating into the local 

underground mine water that drains to site LWLT. The mine 

drainage at site LD showed no correlation with flow either in 

concentration or in the ratio of dissolved to total iron (fig. 18) 

indicating a poor connection with surface runoff. Increased 

flow did not seem to alter the proportion of dissolved to total 

iron at site BC-UMD (fig. 18). 

Total iron concentration was inversely correlated with 

flow at sites BC-DMD and BCM. This correlation results from 

an increase in the proportion of relatively dilute water originating in the headwaters at high flow. At site BCM, dissolved iron 

increased slightly as flow increased. The process causing dissolved iron to increase at BCM during high flow is not clear. 

Although the pH of water at site BCM generally declined with 

increased flow (fig. 16), it remained near-neutral (minimum pH 

= 6.1; table 5) making the dissolution of relatively insoluble 

Fe(OH)3 unlikely over the range of measured pH values. Nonetheless, there are processes facilitated by decreases in pH and 

(or) redox potential of streambed sediments or the water column 

that may increase the concentrations of dissolved metals (Cravotta and Bilger, 2001). 

Manganese

Manganese is a common metal in manganosiderite 

[(Fe, Mn)CO3] (Cravotta and others, 1994) and various other 

minerals associated with iron compounds (Williams and others, 

1995). Little research exists on its effects on aquatic life; however, it is undesirable in water supplies because of discoloration 

effects at concentrations as low as 50 μg/L (Hem, 1985, p. 85). 

Although manganese was lower in concentration than iron, it 

was elevated in mine water discharging from LWLT and LD 

(fig. 19), causing manganese concentrations to commonly 

exceed the water-quality criterion (Pennsylvania Department of 

Environmental Protection, 1998) and TMDL (Susquehanna 

River Basin Commission, 2001) at sites BC-DMD and BCM. 

The oxidation of manganese and formation of solid manganese 

oxides occurs at pH 8.5 or greater (Walton-Day, 1999). As a 

result, manganese was transported conservatively in its dissolved state (Mn2+) at all sites (fig. 19) over the entire range of 

hydrologic conditions (fig. 20).

Mine drainage from sites LWLT, LD, and diffuse seeps 

increased the median total manganese concentration between 

sites BC-UMD and BC-DMD by nearly 500 percent (table 5). 

The largest contributor of manganese was the LD discharge, 

which had concentrations that ranged from 1,910 to 

2,490 μg/L and had a median total manganese concentration of 

2,170 μg/L (table 5). Little change occurred in manganese concentration between sites BC-DMD and BCM (fig. 19). Bear 

Creek significantly increased the median total manganese concentration in Wiconisco Creek (p-value = 0.0003; table 6). The 

manganese concentration at site WC-DBC was about 

100 percent greater than the concentration at site WC-UBC 

(640 compared to 320 μg/L; table 5). The relation between 

manganese and flow (fig. 20) was similar to that previously 

described between iron and flow. 

Aluminum

The chemistry of aluminum in water is complex because it 

can be present in various organic or inorganic complexes that 

are pH-dependent. Aluminum is least soluble between pH 5.7 to 

6.2 and tends to be in solution outside this range (Brown and 

Sadler, 1989). Elevated concentrations of aluminum can occur 

in streams receiving abandoned mine drainage or acid precipitation (Baker and Schofield, 1982) or in streams where leaching 

from mineral soil occurs (Brady, 1990). The aluminum concentration was frequently at or near the detection limit of 

<200 μg/L at all sites (table 5). 

Despite overall low concentrations, aluminum is more 

toxic than iron or manganese and may impair aquatic life at concentrations below 200 μg/L (Baker and Schofield, 1982). Further, aluminum concentrations greater than 500 μg/L will generally kill all fish and many macroinvertebrates (Earle and 

Callaghan, 1998). Toxicity to aquatic life is not only a function 

of concentration but also is related to pH. The most toxic effects 

on fish occur between pH 5.2 and 5.4 (Baker and Schofield, 

1982). Consequently, ANC provided by mine drainage to Bear 

Creek may act to mitigate the effects of aluminum by buffering 

upstream inputs and increasing the pH of creek water to nearneutral. 

Because of a large proportion of aluminum values below 

the detection limit, interpretation of its effects on the chemistry 

of Bear Creek is limited. Nonetheless, the quality-control concentrations of total aluminum reported for each site by USGS 

NWQL in July 2002 were useful to help interpret the total aluminum concentration dataset from the PaDEP laboratory. The 

NWQL reporting limit for total aluminum concentrations was 

30 μg/L compared to multiple detection limits of 200 and 

500 μg/L reported by PaDEP. Aluminum concentrations in 

quality-assurance samples analyzed by NWQL are shown in 

table 3 but are not included in the summary statistics of table 5. 

Aluminum occasionally was detected in the acidic waters 

(median pH = 4.6) of site BC-UMD at concentrations greater 

than or equal to 200 μg/L (table 5). The maximum concentration was 600 μg/L. Because mine drainage was not a major 

component of flow at BC-UMD, the source may be aluminum 

leached from soil as a result of acid precipitation.
Figure 18. Relation of dissolved and total iron to flow at seven sites in the Bear Creek study area, Dauphin County Pennsylvania. Data were colle

to December 2002. One value of dissolved iron concentration censored at <20 μg/L and two values of total iron censored at <300 μg/L were omit

plot. [WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LD, LBC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek]

DISSOLVED AND TOTAL IRON,

IN MICROGRAMS PER LITER

DISSOLVED IRON

TOTAL IRON

EXPLANATION

0 50 125 0 4 8 12 0 5 10 15 20 0 1 2 3 4 0 2

0 1 2 34 5 6 7 0 5 10 15 20

WC-UBC BC-UMD LWLT LD BC-DMD BCM 

FLOW, IN CUBIC FEET PER SECOND 

SAMPLING SITE

0

5,000

10,00015,00020,00025,00030,00035,000

25 75 100
Effects of Drainage From Abandoned Mines on Water Quality 37

Figure 19. Ranges of dissolved and total manganese measured at seven sites in the Bear Creek study area, Dauphin County, 

Pennsylvania, from March 1999 to December 2002. 

[WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level 

Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco 

Creek downstream of Bear Creek]

 WC- BC- LWLT LD BC- BCM WCUBC UMD DMD DBC

75th percentile

25th percentile

Median (50th percentile)

75th percentile plus 1.5 times the interquartile

(18) Sample size

Outlier - point that is 1.5 to 

EXPLANATION

3 times greater than the interquartile range

 range or largest value, whichever is smaller

25th percentile minus 1.5 times the interquartile 

 range or the smallest value, whichever is smaller

Mean

(18)

Dissolved Total 

DISSOLVED AND TOTAL MANGANESE, IN MICROGRAMS PER LITER

Pennsylvania Department of Environmental Protection water-quality criterion for

dissolved manganese (maximum concentration)

0

250

500

750

1,000

1,250

1,500

1,750

2,000

2,250

2,500

2,750

(18)

(42)

(42)

(42)

(42)

(42)

(18)

(18)

(39)

(44)

(39)

(39)

(39)

(17)
Figure 20. Relation of dissolved and total manganese to flow at seven sites in the Bear Creek study area, Dauphin County, Pennsylvania, from to December 2002. [WC-UBC, Wiconisco Creek upstream of Bear Creek; BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level Tunnel; LD, BC-DMD, Bear Creek downstream of mine drainage; BCM, Bear Creek at mouth; WC-DBC, Wiconisco Creek downstream of Bear Creek] DISSOLVED MANGANESE TOTAL MANGANESE EXPLANATION

DISSOLVED AND TOTAL MANGANESE, 

0 50 125 0 4 8 12 0 5 10 15 20 0 1 2 3 4 0 25 

01 2 3 4 5 6 7 0 5 10 15 20

WC-UBC BC-UMD LWLT LD BC-DMD BCM W

FLOW, IN CUBIC FEET PER SECOND 

SAMPLING SITE

0

500

1,0001,5002,0002,500 25 75 100

IN MILLIGRAMS PER LITER
Effects of Drainage From Abandoned Mines on Water Quality 39

In the mine discharges, aluminum most commonly 

exceeded the detection limit at site LWLT where 82 percent of 

the concentrations were greater than 200 μg/L. The range of 

total aluminum concentrations at site LWLT was <200 μg/L to 

1,000 μg/L, and the median was 300 μg/L (table 5). Aluminum 

concentrations at site LD were less than at site LWLT, 

where 97 percent of the values were less than 200 μg/L. In fact, 

total aluminum concentrations reported by the NWQL indicate 

that water discharging from site LD had total aluminum concentrations that were at most about one tenth those of the LWLT 

discharge (<30 μg/L compared to 280 μg/L; table 3). Water 

from LD diluted the higher concentrations of total aluminum in 

water from sites BC-UMD and LWLT because it contributes a 

large proportion of flow to Bear Creek.This dilution effect was 

evident in water at sites BC-DMD and BCM where total aluminum concentrations commonly were equal to or less than 

200 μg/L (table 5). Analyses by the NWQL indicate that the 

concentration of total aluminum in water at sites BC-DMD and 

BCM was 40 μg/L (table 3). 

Mixing of Bear Creek with Wiconisco Creek also resulted 

in an apparent decrease in total aluminum concentration by 

dilution. The median total aluminum concentration at site 

WC-UBC was 200 μg/L compared to the median at site 

WC-DBC of less than 200 μg/L (table 5). Data from the NWQL 

indicate that total aluminum concentration decreased by 

40 μg/L between sites WC-UBC and WC-DBC (table 3).

Metal Loading Rates

Total Maximum Daily Loads (TMDLs) represent numeric 

endpoints used to evaluate the attainment of water-quality standards that, if attained, are expected to restore Bear Creek to a 

cold-water fishery (Susquehanna River Basin Commission, 

2001). TMDLs for metals have been determined for sites 

BC-UMD, LWLT, LD, BC-DMD, and BCM (Susquehanna 

River Basin Commission, 2001). Mean loading rates of dissolved iron and total manganese computed from chemistry and 

flow data collected during this investigation indicate that established TMDLs are equaled or exceeded at all five sites except 

for the total manganese TMDL at site LWLT (table 7). 

Iron and manganese in water draining from LWLT, LD, 

and diffuse zones of seepage increased the mean load of these 

constituents in the downstream reach (fig. 21) of Bear Creek.

The largest iron load to site BC-DMD was contributed by drainage from site LD (54 percent), followed by diffuse zones of 

seepage (30 percent) and drainage from site LWLT (16 percent). Collectively, these mine water inputs increased the mean 

load of iron in Bear Creek (dissolved plus suspended fractions) 

by about 100 times, from 5 lb/d at site BC-UMD to 510 lb/d at 

site BC-DMD (fig. 21). The mean load of manganese (dissolved plus suspended fractions) increased by 30 times from

2 lb/d at site BC-UMD to 60 lb/d at site BC-DMD (fig. 21). 

A small amount of water containing iron and manganese 

entered the stream between BC-DMD and BCM, increasing the 

load at the mouth to 540 lb/d of iron and 70 lb/d of manganese 

(fig. 21). 

Most of the iron in streamwater immediately below the 

mine discharges was in solution. As water flowed downstream, 

a conversion of dissolved iron to Fe(OH)3 occurred (eqn. 4), 

decreasing the median concentration of dissolved iron at BCM 

to 1,320 μg/L compared to the total iron concentration of 

10,600 μg/L. Because of this conversion, dissolved iron made 

up only 19 percent of the mean total iron load at BCM; 81 percent was from iron suspended in the water column. Because a 

large proportion of the iron load at BCM was suspended, 

TMDLs developed for dissolved iron (table 7) were met about 

10 percent of the time (4 out of 42 load computations); the minimum load was 1.0 lb/d. Even though the TMDL was occasionally met, there was no net reduction in the total iron load or corresponding benefits to aquatic life. 

Despite the range of hydrologic conditions during this 

investigation (fig. 7), iron and manganese loading during wet 

periods differed little from dry years. The mean iron loading at 

BCM in 2000, when annual precipitation totaled 51.2 in., was 

550 lb/d, compared to 540 lb/d during drought conditions in 

2001 (2001 annual precipitation was only 33.0 in.). Aboveaverage precipitation and the resulting increase in the water 

level of the mine pool and flow rate of sites LWLT and LD 

seemed to have only a minor effect on iron and manganese loading to Bear Creek. 

Table 7. Computed mean loads of dissolved iron and total manganese compared to Total Maximum Daily Loads at selected sites in 

the Bear Creek watershed, Dauphin County, Pennsylvania. 

[BC-UMD, Bear Creek upstream of mine drainage; LWLT, Lykens Water-Level 

Tunnel; LD, Lykens Drift; BC-DMD, Bear Creek downstream of mine drainage; 

BCM, Bear Creek at mouth]

Site Constituent

Mean load 

(pounds per 

day)

Total Maximum 

Daily Load

(TMDL)1

(pounds per day)

BC-UMD Iron, dissolved2 4 0.20

Manganese, total 2 2.0

LWLT Iron, dissolved 40 1.8

Manganese, total 7 7.7

LD Iron, dissolved 270 .9

Manganese, total 30 19.6

BC-DMD Iron, dissolved 400 5.1

Manganese, total 60 29.9

BCM Iron, dissolved 100 5.6

Manganese, total 70 24.0

1TMDL represents the Total Maximum Daily Load that will allow 

Bear Creek to meet its cold-water fishery designation (Susquehanna 

River Basin Commission, 2001).

2TMDL has not been developed for total iron.
40 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Figure 21. Mean loading rates of total iron (FE) and manganese (MN) in the Bear Creek study area, Dauphin 

County, Pennsylvania. Locations depicted here represent the relative position of each site where loads 

were computed (except for diffuse zones of seepage) and are not to scale. Refer to figure 1 for site 

locations. Unmeasured mine drainage included inputs from mine seeps throughout the watershed. The 

position of unmeasured mine drainage on this figure is not intended to represent the location of a specific 

source or sources. Mean loads, except from unmeasured mine drainage, were computed from 

instantaneous flow and concentration data collected between March 1999 and December 2002. 1

Mean 

loads from unmeasured mine drainage were computed from the difference between Bear Creek 

downstream of mine drainage and the sum of inputs from Bear Creek upstream of mine drainage, 

Lykens Water-Level Tunnel, and Lykens Drift.
Passive-Treatment Technologies for Iron Removal 41

Passive treatment is under consideration by DCCD (2004) 

to improve the quality of mine drainage from sites LWLT, LD, 

and selected diffuse seeps. Preliminary engineering designs by 

Skelly and Loy, Inc. (2003), for treatment of these discharges 

indicate that iron removal is the primary objective. Manganese 

is not a target for treatment because toxicity is not likely at measured concentrations (Earle and Callaghan, 1998) (table 5), and 

removal by passive treatment is not effective below pH 8.5 

(Walton-Day, 1999). The following section describes passivetreatment technologies commonly used to remove iron from 

mine drainage having chemistry similar to that of water discharging from sites LWLT, LD, and selected diffuse seeps.

Passive-Treatment Technologies for Iron 

Removal

Passive treatment refers to treatment that requires minimal 

additional maintenance after implementation to continue to 

receive benefits. The science of iron removal by passive treatment—in terms of matching treatment alternatives with influent 

chemistry—is summarized in figure 22. In general, aerobic 

wetlands and ponds can treat net alkaline water; Anoxic Limestone Drains (ALD) can treat acidic water with low concentrations of Al, Fe3+, and dissolved oxygen; Successive AlkalinityProducing Systems (SAPS), anaerobic wetlands, and Oxic

Determine Flow Rate

Analyze Water Chemistry

Calculate Loadings

ANOXIC

LIMESTONE

DRAIN

AEROBIC or

ANAEROBIC

WETLAND, or

SAPS

Low flow

(<55 gal/min)

Strip DO,

precipitate Fe

OXIC

LIMESTONE

CHANNEL

AEROBIC

POND

AEROBIC

POND

ANAEROBIC

WETLAND, or

SAPS

Net alkaline

water

Net alkaline

DO 2-5 mg/L

Fe 10-25% DO 2-5 mg/LFe 10-25% DO<2 mg/L

Fe < 10%

Al < 25 mg/L

DO<2 mg/L

Fe < 10%

Al < 25 mg/L

AEROBIC

WETLAND

Net

alkaline

water

pH > 4.5

Aerate

Net

acid

water

pH < 4.5

+3

+3

+3

+3

AEROBIC

WETLAND

Net acid water acid water

AEROBIC

POND

High flow (> 55 gal/min) High flow

(> 55 gal/min)

DO > 5 mg/L

Fe >25% DO > 5 mg/LFe >25% +3

Figure 22. Flow chart of passive-treatment alternatives adapted from Hedin and others (1994) and 

Skousen and others (2000). 

[<, less than; >, greater than; %, percent; mg/L, milligrams per liter; gal/min, gallons per minute; SAPS, 

Successive Alkalinity-Producing Systems; DO, dissolved oxygen]
42 Effects of Coal Mining and Drainage From Abandoned Mines on Streamflow and Water Quality, Bear Creek, 1999-2002

Limestone Channels (OLC) can treat acidic water with high 

concentrations of Al, Fe3+, and dissolved oxygen (Skousen and 

others, 2000). These passive-treatment methods are sometimes 

used in combination. For example, mine water may initially be 

routed through relatively deep aerobic ponds that capture most 

of the suspended iron; residual iron can then be removed by 

shallow constructed wetlands located downflow (Hedin Environmental, 2001). The mine drainage from sites LWLT and LD 

has chemical characteristics that can be treated with aerobic 

ponds and (or) wetlands (fig. 22). 

The processes that are most important for removal of iron 

from mine drainage in aerobic ponds and wetlands are (1) oxidation and hydrolysis (eqns. 3 and 4), and (2) deposition of suspended iron precipitates. Thus, iron removal usually can be 

facilitated by adding oxygen to oxidize reduced forms of iron, 

increasing ANC to buffer hydrolysis reactions (eqn. 4), modifying retention time, or some combination of these. Other processes known to remove iron from mine drainage in aerobic 

ponds and wetlands include ion exchange and adsorption of dissolved constituents onto substrate and complexation of dissolved constituents with organic matter. Plant assimilation of 

metals also may play a role in iron removal (Walton-Day, 

1999). 

Addition of ANC to acidic mine drainage entering Bear 

Creek could be important because iron oxidation, hydrolysis, 

and subsequent precipitation of iron are influenced by pH. In 

the absence of excess ANC to buffer the H+ produced from 

hydrolysis (eqn. 4), pH will decrease, resulting in greater solubility of Fe(OH)3 and attenuation of iron oxidation and hydrolysis. A decrease in pH of one unit slows the rate of iron oxidation (and the potential for removal) 100-fold (Hedin and others, 

1994). Hence, iron is removed most effectively when excess 

ANC is present (Hedin Environmental, 2001). The addition of 

ANC in well-oxygenated water like the drainage from site 

LWLT commonly is accomplished by routing mine drainage 

through an oxic limestone channel prior to retention in aerobic 

ponds or wetlands (Hedin and others,1994; Skousen and others, 

2000).

Iron-removal rates per unit area of wetland, based on data 

from wetlands used to treat mine water draining from bituminous coal mines in western Pennsylvania, have been determined 

for different mine-drainage chemistries (Hedin and others, 

1994). These removal rates commonly are used to size wetlands 

or aerobic ponds used for passive treatment. Generally, the rate 

of iron removal increases as concentrations of iron and ANC 

increase. As the rate of iron removal increases, smaller wetland 

and aerobic pond size can accomplish equivalent removal. Iron 

removal rates as high as 20 g m-2 d-1 (178 lb acre-1d-1) and as 

low as 7 g m-2 d-1 (62.5 lb acre-1d-1) have been recommended 

for sizing aerobic ponds and wetlands to treat net alkaline and 

net acidic discharges, respectively (Hedin and others, 1994). 

Because iron concentrations measured in mine water draining 

to Bear Creek are relatively low compared to those reported by 

Hedin and others (1994) and water draining from site LWLT is 

only marginally alkaline, a conservative removal rate of 

6 g m-2 d-1 (53.5 lb acre-1d-1) was recommended by Hedin Environmental (1998) to treat the combined discharges from LWLT, 

LD, and selected diffuse seeps.

Aerobic ponds or wetlands are almost always needed to 

facilitate iron oxidation, hydrolysis, and deposition. Of 46 mine 

drainage sources prioritized for treatment by Cravotta and 

Kirby (2004b) in the Western Middle Field of the Anthracite 

Coal Region (fig. 1), aerobic ponds or wetlands ranging in size 

from <0.1 to 17.8 acres were components of nearly all treatment 

scenarios. Despite the need for aerobic ponds and wetlands, 

land availability frequently constrains their size. As a result, 

they may not be sized large enough to remove all iron even 

though mine water can be pretreated to increase the rate of iron 

removal (fig. 22). In the Bear Creek watershed, options for 

reshaping land or routing discharges to locations that are more 

amenable to treatment are limited by steep topography. Thus, 

the level of iron removal in Bear Creek watershed is dictated by 

the land area that is available for construction of aerobic ponds 

and wetlands rather than by the chemical characteristics of 

drainage from sites LWLT, LD, or diffuse seeps. 

On the basis of water-chemistry data collected by USGS 

and topographic surveys of Bear Creek watershed, Skelly and 

Loy, Inc. (2003), designed a series of three aerobic ponds 

(fig. 1) totaling approximately 1.5 acres to treat mine drainage 

from site LWLT. A separate conceptual design by Skelly and 

Loy, Inc. (2003), is under consideration (2004) by DCCD to 

treat water discharging from LD. Both treatment systems were 

designed to maximize mine-drainage retention time and iron 

removal within the constraints of available land near each discharge. 

Summary and Conclusions

The Dauphin County Conservation District, through the 

Pennsylvania Department of Environmental Protection Growing Greener Program, and the U.S. Geological Survey cooperated in an investigation from March 1999 to December 2002 to 

evaluate the effects of historical coal mining and drainage from 

abandoned mines on streamflow and water quality in Bear 

Creek. Hydrologic and chemical data for the evaluation were 

collected at seven stream sites on Bear Creek, two mine discharges entering Bear Creek, and two stream sites on Wiconisco Creek (one upstream and one downstream of Bear Creek). 

These data were used to quantify baseline variability in flow 

characteristics, to demonstrate that discharges located close 

together can have markedly different chemical characteristics, 

and to document loadings of iron and manganese, which waterresources managers can use to determine an appropriate passive-treatment technology. The range of flows and chemical 

compositions documented in mine discharges targeted for treatment in the Bear Creek watershed are characteristic of water 

from many underground mines in the Southern Anthracite Coal 

Field. 
Acknowledgments 43

Streamwater loss upstream of mine-discharge contributions was commonly 100 percent during periods of minimal 

precipitation. The streambed was frequently dry during summer 

months because of permeable and possibly fractured substrate 

that facilitates streamwater infiltration. Instantaneous flow at 

Bear Creek upstream of mine drainage (BC-UMD) ranged from 

0 to 9.7 ft3/s and had a mean of 1.9 ft3/s. 

When water loss above the mine discharges was 

100 percent, base flow in Bear Creek was entirely abandoned 

mine drainage from the LWLT, LD, and diffuse zones of seepage. Mean streamflow computed from continuous measurements (15-minute intervals) at Bear Creek downstream of mine 

drainage (BC-DMD) was 8.4 ft3/s over the study period. Daily 

means ranged from 1.2 to 108 ft3/s. Storm events influenced the 

short-term response of streamflow but had little effect on mine 

drainage from LWLT and LD because of the large storage 

capacity of the underlying mine pool (980 million ft3; 

7.33 bgal). Unimpacted streamflow above the mine discharges 

accounted for 16 percent of streamflow under base-flow conditions and 47 percent under stormflow conditions. 

The chemistry of Bear Creek upstream of the mine discharges was characterized by aerobic (median dissolved oxygen 

concentration = 10.0 mg/L), weakly acidic (median pH = 4.6, 

net acid neutralizing capacity (ANC) = -9 mg/L as CaCO3) 

water with low metals concentration (median total iron = 

550 μg/L, manganese = 300 μg/L). Streamwater downstream of 

the mine discharges was also aerobic (median dissolved oxygen 

= 9.4 mg/L), but pH and total iron and manganese concentrations were significantly higher (p-values = <0.0001). The 

increase in pH was chiefly because of the buffering effect of 

ANC in mine water discharging from site LD (median net ANC 

= 123 mg/L as CaCO3). Exsolution of carbon dioxide (CO2) 

and hydrogen sulfide (H2S) from water discharging at LD and 

associated seeps elevated pH in the downstream reach of Bear 

Creek. The increase in iron and manganese downstream of mine 

discharges was a result of elevated metals concentrations in 

water discharging from LWLT (median total iron = 

10,000 μg/L, manganese = 890 μg/L), LD (median total iron = 

19,000 μg/L, manganese = 2,170 μg/L), and diffuse zones of 

seepage. 

Most of the iron in streamwater immediately below the 

mine discharges was in solution (median dissolved iron concentration = 9,970 μg/L), indicating that the traveltime between LD 

and BC-DMD was too short to allow significant oxidation and 

hydrolysis of iron to occur. As water flowed downstream, oxidation and hydrolysis reactions converted dissolved iron to 

Fe(OH)3, decreasing the median concentration of dissolved iron 

at the mouth to 1,320 μg/L, compared to median total iron concentration of 10,600 μg/L. Consequently, the load of dissolved 

iron at the mouth of Bear Creek made up only about 19 percent 

of the total iron load. The remaining 81 percent of iron load was 

from precipitated iron particles suspended in the water column. 

The distinction between dissolved and suspended iron load 

is important because the Total Maximum Daily Load (TMDL) 

for iron in Bear Creek has only been developed for dissolved 

species. On the basis of instantaneous concentration and flow 

data, mean total iron and manganese loads at the mouth of Bear 

Creek were 540 and 70 lb/d, respectively. Because the portion 

of the total iron load attributable to dissolved iron varies significantly at the mouth, the TMDL for dissolved iron at the mouth 

was met approximately 10 percent of the time (4 out of 

42 observations). These instances of TMDL attainment were 

not indicative of improvement in water quality or benefits to 

aquatic life. To properly interpret any improvement achieved 

through attainment of TMDLs developed for dissolved constituents, data for the corresponding suspended fraction are essential. 

Acknowledgments

John Orr, Andrew McAllister, and Jeremy Trexel of 

DCCD, and Charles McGarrell of PaDEP (formerly of DCCD) 

were instrumental in project support, coordinating project activities, and field work. Daniel Koury of PaDEP served as liaison 

with the PaDEP laboratory, which provided most of the waterchemistry analyses. David Saad of USGS provided valuable 

guidance and technical assistance throughout the writing of this 

report. 

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