The U.S. Geological Survey (USGS) is 

involved in mapping and studying land, mineral, biological, and water resources and 

determining the risk from earthquakes and 

other natural hazards, which are of importance to the citizens of Pennsylvania. This 

Fact Sheet describes how the USGS is 

addressing some of the major environmental 

issues in Pennsylvania, which include availability of mineral resources; contamination 

of the environment by hazardous wastes; 

effects of coal mining, oil and gas production, and agriculture on the environment; 

nutrient input to streams and estuaries; and 

adequacy of good-quality water supplies. 

Information on acquiring the thousands of 

map, book, and aerial photographic products 

of the USGS also is given.

Mineral-Resource Information

The USGS Mineral Resource Data System (MRDS) is a digital data base that contains information from more than 110,000 

sites nationwide and worldwide. The MRDS 

provides information on the occurrence of 

minerals and related data to Federal and State 

agencies, industry, and the public. The 

MRDS contains information on about 800 

sites in Pennsylvania that relates mostly to 

deposits of iron, limestone, sand, and gravel.

Mineral-Resource Assessment

The USGS is completing a prototype 

quantitative national assessment of mineral 

resources for five commonly used metals—

gold, silver, copper, lead, and zinc. The 

assessment lists significant known deposits, 

identifies areas with mineral potential, and 

estimates the quantity of each metal present. 

As a complement to the national assessment, 

the USGS is conducting a more-comprehensive regional assessment of the metallic- and 

industrial-mineral resources in the Eastern 

United States. As part of this regional work, 

the USGS is preparing an inventory of 

known mineral resources in Pennsylvania 

and is assessing the potential for undiscovered mineral resources. This work involves 

compilation of digital geological, geophysical, geochemical, and mineral-deposit data. 

Products include traditional maps and digital 

(CD–ROM) data sets. 

Continuous-Type Natural Gas 

Accumulation

A natural gas accumulation of regional 

dimensions may be present in Lower Silurian 

sandstone reservoirs in northwestern Pennsylvania, eastern Ohio, western New York, 

and western West Virginia. This continuoustype accumulation is at the edge of largely 

depleted oil and natural gas fields in central 

and east-central Ohio. The reservoirs of the 

continuous-type accumulation are at greater 

depth, are less permeable, and yield less gas 

per well than reservoirs in discrete-type 

accumulations. However, reservoirs in the 

continuous-type accumulation probably are 

gas saturated, and nearly all wells completed 

in this accumulation should be productive 

after hydrofracturing. Several tens of trillions 

of cubic feet of gas may be recoverable from 

the accumulation. The USGS has begun a 

multi-year investigation to increase understanding of the nature, size, and origin of the 

accumulation.

Contamination of Water by 

Hazardous Wastes

The USGS, in cooperation with the U.S. 

Department of Defense and the U.S. Environmental Protection Agency (USEPA), has 

studied hazardous wastes in ground water at 

numerous sites in Pennsylvania. For example, the USGS recently completed a study at 

a Superfund site at Warminster in Bucks 

County (fig. 1, site 1) to determine the distribution, transport, and fate of volatile organic 

compounds (VOC’s). Several methods were 

used to investigate the geohydrology of the 

site, including borehole geophysical logging, 

measurement of vertical borehole flow, isolation of specific zones in the borehole for 

depth-discrete hydraulic testing and watersample collection, drilling, coring, installation of monitor wells, and continuous waterlevel monitoring.

Borehole geophysical logs were used to 

construct a map of the underground rock layers at the site. Borehole television surveys 

(fig. 2) were used to help understand the geophysical logs and to locate smooth sections 

of the boreholes where packers could be 

inflated. Aquifer-isolation tests were run in 

six boreholes by inflating rubber-bladder 

packers above and below a water-bearing 

Index of Subjects

Mineral-Resource Information 

Mineral-Resource Assessment

Continuous-Type Natural Gas Accumulation

Contamination of Water by Hazardous Wastes

Discharges From Coal Mines

Sediment in the Lower Susquehanna River

National Water-Quality Assessment Program

Geologic and Hydrologic Mapping

Topographic Mapping

Collection of Hydrologic Data

Cooperative Programs

Figure 2. Photograph from a borehole television 

survey showing a water-producing fracture 

247.8 feet below land surface.

EXPLANATION

 1 Warminster 6 Lake Aldred

 2 Stonycreek River Basin 7 Conowingo Reservoir

 3 Swatara Creek Basin 8 Allentown quadrangle

 4 Old Forge borehole 9 Delaware Water Gap 

 5 Lake Clarke National Recreation Area

Figure 1. Locations of selected USGS studies.

1

4

5

6

7

9

2

3

8

8

P E N N S Y L V A N I A

Earth Science in the Public Service
fracture. By placing a pump between the 

packers, hydraulic testing was conducted, 

and a water sample for laboratory analysis 

was collected. Elevated quantities of several 

VOC’s were detected in most water samples.

The downward hydraulic head gradient at 

the site, which was partly the result of the 

pumping of nearby public supply wells, 

caused the downward vertical migration of 

VOC’s deeper into the aquifer through three 

wells with open-hole construction in the 

main contamination area. The VOC’s then 

moved outward into the aquifer at different 

depths in response to the pumping of nearby 

wells and natural hydraulic gradients. The 

results of this study are enabling the USEPA 

to evaluate and improve the remedial activities at the site.

Discharges From Coal Mines

Acidic drainage from abandoned and 

active coal mines has affected more than 

2,400 miles of streams and associated 

ground water in Pennsylvania. Increased 

concentrations of sulfate and metals in mine 

drainage make the water unfit for most uses 

and are toxic to aquatic organisms. To assist 

State, Federal, and local agencies in their 

efforts to remediate and improve utilization 

of affected waters, the USGS has documented the extent and severity of surface-water 

and ground-water contamination associated 

with bituminous coal mining in western 

Pennsylvania and anthracite coal mining in 

eastern Pennsylvania and has evaluated the 

effects of mining and reclamation practices 

and water-treatment methods on water quality. These studies have been supported by 

the USEPA, the Office of Surface Mining, 

the Pennsylvania Topographic and Geologic Survey of the Department of Conservation and Natural Resources (PaDCNR), the 

Pennsylvania Department of Environmental 

Protection (PaDEP), the Philadelphia Water 

Department, the Somerset County Conservation District, coal companies, and The 

Pennsylvania State University. 

In the Stonycreek River Basin in Somerset and Cambria Counties (fig. 1, site 2), 

270 discharges from coal mines were precisely located, sampled, and prioritized 

(ranked) with respect to their loading on the 

receiving stream, and 37 streamwater sites 

were sampled during base-flow conditions. 

A ranking index was developed for all 

streams in six subbasins of the Stonycreek 

River Basin that were moderately to severely affected by discharges from coal mines. 

This ranking provides a basis for selecting 

the sites for remediation that will provide 

the greatest improvement in stream quality 

at the least cost.

In the Swatara Creek Basin in Schuylkill 

County (fig. 1, site 3), mine-drainage treatment systems are being evaluated to improve 

understanding of the treatment process, so 

that PaDEP can design cost-effective treatment systems to protect water quality in a 

proposed reservoir. At the opening to the 

Orchard Mine, three 80-foot-long limestone 

drains were constructed in parallel; access 

points in the drains enable collection of 

water, gas, and rock samples. As water flows 

through the drains, concentrations of alkalinity and calcium increase; concentrations of 

acidity and dissolved and suspended iron 

and aluminum decrease; and concentrations 

of sulfate, magnesium, manganese, and trace 

metals are unchanged. Water at the inflow 

was very acidic; at the outflow it was nearly 

neutral.

A USGS study of large discharges from 

mines in the anthracite coal fields shows that 

many mines discharge water with increased 

concentrations of aluminum, calcium, cobalt, 

iron, lithium, magnesium, manganese, nickel, strontium, zinc, and sulfate. From 1975 to 

1991, the acidity of water discharged from 

most mines in this region decreased and concentrations of iron, manganese, and sulfate 

decreased. Figure 3 shows the decrease in 

iron concentration in water from the Old 

Forge borehole (fig. 1, site 4), which is a 

major discharge point in the Northern 

Anthracite Field. Borehole discharge ranges 

from about 4 to 400 cubic feet per second, 

but discharge does not appear to have any 

long-term trend. Changes in the exposed surface area of limestone drains caused by dissolution and, possibly, coating of sulfide 

minerals probably account for most of the 

improvement in water quality with time that 

has been observed at many mines in the 

anthracite region. This study provides the 

data that PaDEP can use to plan remedial 

activities and to determine the effects of new 

mining on water quality.

Sediment in the Lower 

Susquehanna River

Many State and Federal agencies are 

involved in a major effort to protect and 

improve water quality in the Chesapeake Bay. 

The USGS has undertaken several studies to 

support this effort.

The Susquehanna River drains 27,510 

square miles in New York, Pennsylvania, and 

Maryland and is the largest contributor of 

sediment to the upper Chesapeake Bay. Data 

collected by the USGS and the Susquehanna 

River Basin Commission have shown that, in 

an average year, streams in the Basin transport 150 pounds per acre of sediment from 

forested land, 1,100 pounds per acre from 

cropland, and 2,200 pounds per acre from 

areas that are undergoing development. During an average year, the Susquehanna River 

transports about 3.3 million tons of sediment, but only 0.89 million tons enters the 

Chesapeake Bay.

Three large hydroelectric dams span the 

lower Susquehanna River. Safe Harbor (Lake 

Clarke) and Holtwood (Lake Aldred) are in 

southern Pennsylvania, and Conowingo 

(Conowingo Reservoir) is in northern Maryland about 10 miles upstream from the Chesapeake Bay (fig. 1, sites 5, 6, 7). The 

reservoirs behind the dams have trapped large 

quantities of sediment, nitrogen, and phosphorus and kept the sediment and nutrients 

from reaching the Bay. In fall 1990, sediment 

stored in the three reservoirs was about 260 

million tons. About 33 percent of the sediment in the three reservoirs is sand and coal. 

The sediment in the reservoirs contained 

about 814,000 tons of organic nitrogen, 

98,900 tons of ammonia (as nitrogen), and 

226,000 tons of phosphorus.

Lake Aldred and Lake Clarke reached 

equilibrium with incoming river sediment by 

1910 and 1950, respectively, and have no 

capacity to store additional sediment. The 

original (1928) capacity of the reservoir 

formed by Conowingo Dam was about 

300,000 acre-feet. USGS studies show that by 

1990, deposition of sediment reduced 

the capacity to 196,000 acre-feet. When 

0

300

20

40

60

80

100

120

140

160

180

200

220

240

260

280

IRON CONCENTRATION, IN MILLIGRAMS PER LITER

1965 1970 1975 1980 1985 1990 1995

YEAR

NUMBER OF VALUES 

MEAN IRON 

6

23

30

32

31

2

3

8

10 12

12

1960

6

USED TO COMPUTE

CONCENTRATION

Figure 3. Annual mean iron concentration in 

water discharged from the Old Forge borehole, 

Northern Anthracite Field, northeastern 

Pennsylvania, from 1962 to 1991.
Lower

Susquehanna

Allegheny

Monongahela

and

Delaware

Potomac

PENNSYLVANIA

0

0

5,000 FEET

1,000 METERS

39o 40'

39o 45'

76o 15' 76o 10'

Michael

Run

FRAZER

TUNNEL

WILDCAT

Broad

Creek

Conowingo

Creek

Funks

Run

CONOWINGO

DAM

POWERPLANT

Holloway's

Run

TUNNEL

locations

cross section

CONOWINGO

RESERVOIR

PENNSYLVANIA

MARYLAND

Conowingo Dam was completed in 1928, the 

reservoir ranged from 100 feet deep just 

above the dam at Holloway’s Run to about 60 

feet deep at Broad Creek. Surveys by the 

USGS in 1993 indicated depths of about 62 

feet just above the dam and about 22 feet at 

Broad Creek (fig. 4). Once the average depths 

in the reservoir are reduced to about 55 feet 

just above the dam and to about 15 feet at 

Broad Creek, the reservoir will no longer 

accumulate sediment. Conowingo Reservoir 

will probably reach equilibrium and cease to 

accumulate sediment in the next 20 or 30 

years. As the capacity of Conowingo Reservoir to store additional sediment decreases, 

the loads of sediment, nitrogen, phosphorus, 

and metals that reach the Chesapeake Bay 

from the Susquehanna River will increase. 

Because this may adversely affect habitat in 

the Bay, understanding the effect that reservoir filling will have is of critical importance 

for planning the actions that need to be taken 

to protect the Bay.

National Water-Quality 

Assessment Program

The National Water-Quality Assessment 

(NAWQA) Program involves studies of 60 

major hydrologic basins of the United States. 

It is designed to describe the status and trends 

in the quality of the Nation’s surface-water 

and ground-water resources and identify the 

natural and human factors that affect the 

water quality. The NAWQA Program 

includes four river basins in Pennsylvania. 

The Lower Susquehanna and the Potomac 

River Basin studies began in 1991. The Ohio 

River Basin (Allegheny and Monongahela 

Rivers) study began in 1994. A NAWQA Program study of the Delaware River Basin is

scheduled to begin in 1997 (fig. 5).

Consistent study designs are achieved by 

dividing the Basins into subunits on the basis 

of physiography, lithology of bedrock, and 

land use. By using standardized methods of 

sampling and data analysis, results are comparable among different river basins and 

subunits.

The primary focus of the Lower Susquehanna and the Potomac River Basin studies 

has been on the occurrence of nitrogen, phosphorus, and herbicides. The concentrations 

of nitrogen and herbicides indicate that the 

streams and ground water in each of the subunits have different sources of these contaminants and different degrees of water-quality 

problems. For example, concentrations of 

nitrate nitrogen in streams and ground water 

from agricultural subunits underlain by limestone bedrock are significantly higher than 

average values from the other subunits with 

less agricultural land use. In addition to 

water quality related to agriculture, such 

important issues as bacteria and radon concentrations in water from rural wells and the 

concentrations of VOC’s have been 

addressed in these studies.

The USGS, in cooperation with several 

other Federal agencies, is acquiring satelliteimage data for the entire United States to provide current information on land use. These 

data are used by the NAWQA Program 

projects to help determine the effects of land 

use on water quality.

Geologic and Hydrologic 

Mapping

Bedrock and surficial geologic maps and 

hydrologic maps are prepared by the USGS. 

These maps are essential for studies of water 

contamination, resource availability, environmental effects of mineral extraction, hazard 

mitigation, and land-use management.

The USGS, in cooperation with the Pennsylvania Topographic and Geologic Survey 

and Bloomsburg University, is preparing 

surficial and bedrock geologic maps of the 

Allentown 1:100,000 quadrangle and component 1:24,000 quadrangles (fig. 1, site 8). 

These maps and derivative products are 

being used by the Lehigh–Northampton 

County Joint Planning Commission to develop wellhead-protection strategies. The USGS 

also is cooperating with the National Park 

Service in the Delaware Water Gap National 

Recreation Area (fig. 1, site 9) by supplying 

and interpreting geologic data for public outreach, training of park rangers, and park 

management.

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

POINT ABOVE 

BROAD CREEK

WILDCAT

TUNNEL

DISTANCE FROM WEST BANK, IN THOUSANDS OF FEET

HOLLOWAY’S

RUN

FUNKS

RUN

0 1 2 3 4 5 6

DISTANCE FROM WEST BANK, IN THOUSANDS OF FEET

0 1 2 3 4 5 6

1993

1959

1993

1959

DEPTH BELOW NORMAL WATER LEVEL, IN FEET

Figure 4. Depth to bottom sediments at two cross sections in Conowingo Reservoir, 1959 and 1993. (Data for 1959 were 

collected by the Johns Hopkins University.)

Figure 5. Locations of National Water-Quality 

Assessment Program study units.
- In preparation - Available

EXPLANATION

Topographic Mapping

The National Mapping Program of the 

USGS strives to ensure the availability of map 

data in graphic and digital forms to the public 

through timely data collection and revision 

procedures. 

Among the most popular and versatile 

products of the USGS are its 1:24,000-scale 

topographic maps (1 inch on the map represents 2,000 feet on the ground). These maps 

depict basic natural and cultural features of 

the landscape, such as lakes and streams, 

highways and railroads, boundaries, and geographic names. Pennsylvania is covered by 

876 maps at this scale. About 90 percent of 

Pennsylvania is covered by digital elevation 

model (DEM) data and work is in progress to 

complete the coverage. Among other uses, 

DEM’s have been used to construct hydrologic models, determine landslide probability, 

and assist in forest fire control.

The USGS, in cooperation with PaDCNR, 

completed statewide aerial photographic coverage between 1992 and 1994 that is being 

used to prepare digital orthophotoquads 

(DOQ). A DOQ is derived from digitized 

aerial photographs, with displacement caused 

by camera tilt and terrain relief removed. It 

combines the image characteristics of a photograph with the geometric qualities of a map. 

They are becoming increasingly useful in 

geographic information system databases, 

where they are used in combination with other data. DOQ’s have been completed for 10 

counties and are being prepared for 18 counties (fig. 6). The USGS, in cooperation with 

PaDEP, was preparing statewide 1:24,000-

scale digital raster graphic (DRG) coverage 

during 1995. A DRG is a scanned image of a 

topographic map that retains the positional 

accuracy of the map in raster format. A DRG 

can be the basic reference layer for a geographic information system, thus allowing 

digital spatial data to be overlaid or integrated 

with a high degree of accuracy. The USGS 

and PaDEP are cooperating on the production 

USGS State representative

840 Market Street

Lemoyne, PA 17043-1586

(717) 730-6900

Fax: (717) 730-6997

Email: dc_pa@usgs.gov

Additional earth science

information can be found by

accessing the USGS Home Page

on the World Wide Web at

http://www.usgs.gov/

For more information on

all USGS reports and products

(including maps, images,

and computerized data), call

1-800-USA-MAPS

The USGS provides maps,

reports, and information to help

 others meet their needs to manage,

develop, and protect America’s water,

 energy, mineral, biological, and land

resources. We help find the natural

resources needed to build tomorrow

and supply the scientific understanding needed to help minimize or mitigate the effects of natural hazards

and environmental damage caused

by natural and human activities. The

results of our efforts touch the daily

life of almost every American.

U.S. Geological Survey

Fact Sheet FS-038-96

Figure 6. Digital orthophotoquad coverage for 

Pennsylvania.

and demonstration of a spatial data set of the 

Lake Erie shoreline to be used for coastal 

zone management. This data set is available 

on CD–ROM and includes DRG’s, DOQ’s, 

DEM’s, and digital line graphs. 

An Earth Science Information Center operated by the Pennsylvania Topographic and 

Geologic Survey in Harrisburg, provides 

information on such earth science topics as 

cartography, geography, digital data, remote 

sensing, geology, geophysics, geochemistry, 

hydrology, aerial photography, and land use. 

The Center is operated in cooperation with the 

USGS and is supported by the USGS with reference materials, technical assistance, training 

and outreach activities, and access to USGS 

data bases.

Collection of Hydrologic Data

The USGS, in cooperation with more than 

30 local, State, and Federal agencies, collects 

streamflow, ground-water, and water-quality 

data at sites throughout Pennsylvania. Many 

of these data-collection sites are equipped 

with data-collection platforms that use radio 

and satellite relay technology to provide nearrealtime data to the users. These data are helpful for day-to-day administration and management of water resources, determining the 

extent and severity of droughts, characterizing 

and predicting conditions during floods, and 

monitoring the effects of human activities on 

water resources, among other uses.

Cooperative Programs

The USGS cooperates with more than 30 

local, State, and Federal agencies in Pennsylvania. Cooperators include State agencies, 

counties, municipalities, basin commissions, 

water authorities, universities, and other Federal agencies. Cooperative activities include 

water-resources data collection, interpretive 

water-availability and water-quality studies, 

mineral-resource assessments, mapping, and 

studies of channel instability and scour at 

more than 16,000 highway bridges over water. 

When local or State agencies are involved, 

activities typically are funded by USGS and 

cooperating agencies on a 50–50 matching 

basis. In addition to the agencies already mentioned, the USGS in Pennsylvania cooperates 

with the U.S. Army Corps of Engineers, the 

Chester County Water Resources Authority, 

the Delaware River Basin Commission, and 

the Pennsylvania Department of Transportation, to name only a few.

The USGS provides support to the Environmental Resources Research Institute of the 

Pennsylvania State University, which conducts a program of research, education, and 

information and technology transfer.