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

U.S. Geological Survey

Programs in Delaware

ATLANTIC OCEAN

CHESAPEAKE BAY

DELAWARE BAY

New Jersey

Pennsylvania

Maryland

Virginia

Fall Line

Delaware

The U.S. Geological Survey (USGS) 

has served as the Nation’s principal 

collector, repository, and interpreter of

natural-science data for more than a 

century. In this capacity, the USGS in 

Delaware works in partnership with 

municipal public-works departments, 

public-health agencies, water and sanitation districts, other Federal agencies, and 

State and county agencies. The USGS, as 

the Nation’s principal agency for natural 

science, provides the national perspective to the many programs that are done 

in concert with these agencies.

National Water-Quality 

Assessment

The effect of human activity on water 

quality is an important and visible environmental issue in the Nation. In response 

to this concern, the USGS is conducting 

the National Water-Quality Assessment 

(NAWQA) Program, which is a comprehensive assessment of water quality in 60 

large regions across the Nation. The purpose of this Program is to assess current 

water-quality conditions and to investigate the effects of natural and human factors on water quality. The Delmarva 

Peninsula is 1 of the 60 study areas 

included in the NAWQA Program (fig. 1). 

The study is federally funded; however, 

the USGS is working in partnership with 

Federal and State agencies that also conduct research and that regulate water 

quality and manage resources.

Maintenance or improvement of 

ground- and surface-water quality are 

important considerations in managing 

land-use practices on the peninsula. 

The Delmarva Peninsula study has provided resource managers with useful 

information on the relation of waterquality problems to agricultural and residential land use. The study has shown that 

although high concentrations of nitrate 

(greater than 10 milligrams per liter as 

nitrogen), a known human-health hazard, 

are present in approximately 15 percent of 

the water samples from wells in the surficial aquifer, the distribution of the nitrate 

concentrations differs regionally in relation to changes in geology, soils, land use, 

and hydrologic flow patterns. High nitrate 

concentrations in the surficial aquifer are 

more likely in upland areas (fig. 1), where 

soils typically are well-drained and sandy 

and the predominant land use is agriculture, than in other parts of the Peninsula. 

High nitrate concentrations also are found 

in deep parts of the surficial aquifer. Pesticides, which are widely present in water 

from shallow parts of the surficial aquifer 

at concentrations below the U.S. Environmental Protection Agency (USEPA) 

Health Advisory Limits, are not presently 

found in deep parts of the aquifer.

Index of Subjects

National Water-Quality Assessment

Ground-Water Flow and Water Quality at 

Dover Air Force Base

Ground-Water Flow in Delaware City Area

Hydrologic Hazards

Data Networks and Water Use

Biological Resources

Topographic Mapping

Earth Science Information Center

Metallic Mineral-Resource Assessment 

Cooperative Programs

Figure 1. Hydrogeomorphic regions in the 

surficial aquifer in the Delmarva Peninsula.

Earth Science in the Public Service
The Delmarva Peninsula study also 

examined chemical patterns in ground 

and surface water in small watersheds 

representing different landscapes on the 

peninsula. Nitrate presently in the 

ground-water system will continue to 

discharge to streams for at least the next 

few decades. Landscape characteristics, 

such as the amount of forest cover and of 

poorly drained soil and channel slope in 

a small watershed, were statistically 

related to the major processes that affect 

water chemistry.

Ground-Water Flow and 

Water Quality at Dover Air 

Force Base

The USGS is providing multidisciplinary technical assistance on environmental issues at Dover Air Force Base. 

The USGS is assessing ground-water flow 

in the surficial aquifer and determining 

whether or not contaminants at several 

previous waste disposal sites are naturally 

attenuating at rates that are adequate to 

prevent risk of offsite contamination. This 

is being accomplished by drilling wells, 

sampling ground water, and sampling 

soils in selected areas of the base; determining the capacity of soils and aquifer 

materials to attenuate contaminants naturally; and developing computer models to 

estimate ground-water flow and pollutant 

transport in parts of the base. 

On the east side of Dover Air Force 

Base, disposal of fuel hydrocarbons and 

degreasing solvents has resulted in contamination of the water-table aquifer. 

Both the analysis of the ability of the 

aquifer materials to attenuate the contaminants and the results of a geochemical 

model specific for the site indicate that 

intrinsic remediation is sufficient for 

decreasing contaminant concentrations to 

acceptable off-site levels.

Ground-Water Flow in the 

Delaware City Area

Understanding how ground water 

becomes contaminated can lead to 

informed decisions on ways to protect 

drinking-water supplies. The USGS provides technical assistance to the USEPA, 

Region III, Resource Conservation and 

Recovery Act Division, with computerized simulations of ground-water flow in 

the Delaware City area. To simulate 

ground-water flow in the area, the USGS 

collects data, develops models of groundwater flow by means of a geographic 

information system, and models possible 

ways to reduce ground-water contamination caused by leaks from hazardouswaste sites in the Delaware City area. 

These efforts will help the USEPA to 

develop effective and economical plans to 

reduce contamination in this area.

Hydrologic Hazards

Floods and droughts can adversely 

affect the agricultural sector of the 

State’s economy as well as public safety. 

The USGS, in cooperation with the Delaware Geological Survey (DGS), is 

improving the accuracy of estimates of 

the severity of floods and droughts. 

State, county, and local planning officials 

use the estimates to develop improved 

strategies for water management and the 

design of infrastructure.

The Delaware Department of Transportation (DelDOT), which provides 

cooperative funds for studies of flood 

magnitude and frequency, and the Delaware Department of Natural Resources 

and Environmental Control, which cooperated with the USGS in a study of the 

frequency of low streamflows, are two of 

the agencies that rely on the results of 

USGS studies. Results of these studies 

are used by the DelDOT to reduce maintenance, repair, and replacement costs 

for highway bridges and to improve the 

safety of travelers during floods. State 

and local agencies use the results of the 

low-streamflow study to allocate surface 

water and evaluate droughts, thereby 

allowing appropriate water-supply decisions that ensure that the water needs of 

the greatest number of people are met to 

the greatest possible extent. Such contributions to public safety and well-being 

make USGS reports valuable to the citizens of Delaware.

Data Networks and Water Use

The amount and quality of ground and 

surface water are vital to the citizens of 

Delaware. The USGS operates a cooperative network of 14 streamflow-gaging stations, 6 tidal gages, and numerous waterlevel gaging stations at wells to collect the 

data necessary to evaluate hydrologic 

conditions. The locations of streamflowgaging stations that were active after 1980 

are shown in figure 2.

The detection of contamination and 

the prediction of contaminant movement 

in ground water are important in the part 

of Delaware south of the Chesapeake & 

Delaware Canal, where ground water supplies most freshwater needs. Similarly, 

maintaining adequate supplies of surface 

water for public consumption in northern 

Delaware and for fisheries and other 

industries, the support of wildlife, and 

recreation are also important issues. The 

USGS systematic data-collection program 

in Delaware received cooperative support 

from the Delaware Geological Survey, the 

Delaware Department of Natural 

Resources and Environment Control, the 

Delaware Department of Transportation, 

the U.S. Environmental Protection 

Agency, the U.S. Army Corps of Engineers, and other organizations. The USGS 

has an important role in collecting data to 

address these issues. The availability of 

up-to-date data on water levels and water 

quality and its use by water-resource 

managers to help maintain the quantity 

and quality of water needed for future use 

make the USGS systematic data-collection program an integral part of waterresources management in Delaware. 
DELAWARE BAY

C&D CANAL

Dover

• Delaware City

Bombay Hook

National

Wildlife Refuge

✪

0 10 Miles

0 10 Kilometers

SCALE

Topographic Mapping

The use of maps and digital cartographic data is widespread and demand 

for this information continues to grow. 

The USGS strives to ensure the availability of map data in graphic and digital form 

to the public through timely and effective 

data-collection and revision procedures. 

The USGS also fosters partnerships with 

other Federal and State agencies to 

improve data collection and to maximize 

resource sharing. In 1995, under a cooperative agreement with the DelDOT, the 

USGS assisted DelDOT’s efforts to prepare digital orthophotoquads (DOQ) that 

meet USGS technical standards for image 

quality, resolution, and format. A DOQ is 

derived from an aerial photograph that 

has been corrected for displacement 

caused by camera tilt and terrain relief. A 

DOQ combines the image characteristics 

of a photograph with the geometric qualities of a map. The DelDOT has provided 

the USGS with 1:12,000-scale color 

infrared DOQ’s covering the entire State. 

The DOQ’s are being archived by the 

USGS for distribution.

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. 

Delaware is covered by 57 maps at this 

scale. These maps have long been favorites with the general public for outdoor 

uses, as well as with scientists and engineers for technical applications. Digital 

cartographic data, including boundaries, 

transportation, and hydrography captured 

from the 1:24,000-scale map series are 

available statewide. The USGS, in cooperation with the DGS, funded a 6-year 

statewide revision of the 1:24,000-scale 

topographic maps covering Delaware.

Figure 2. Locations of continuous streamflowgaging stations (solid triangles) in Delaware that 

were active after 1980.

Since 1950, the USGS has published 

reports at 5-year intervals on the estimated use of water in the United States. 

Estimates of water use in Delaware are 

combined with estimates by other States 

and water-resources regions in accordance with methods and standards to meet 

regional and national needs.

Biological Resources

 The USGS Biological Resources 

Division (formerly the National Biological Service) cooperates with other Federal and State agencies to assess the type, 

quantity, health, and diversity of biological resources in Delaware. The Delaware River, Delaware Bay, Chesapeake 

Bay, and the Bombay Hook National 

Wildlife Refuge are current locations for 

USGS biological research and study in 

Delaware. Study topics include habitat 

restoration for fish and bird species; 

assessing the effects of pesticides on 

aquatic life; mapping the diversity of 

plant and animal communities through 

the use of satellite imagery; gathering 

and analyzing quantitative information 

on populations of breeding birds; and 

assessing the effects of urbanization on 

fish in certain river reaches.
For More

Information

Earth Science Information 

Center

The Earth Science Information Centers (ESIC’s) provide information to the 

public about USGS programs, products, 

and technological developments. The 

ESIC in Newark, Delaware, was established under a cooperative agreement 

between the USGS and DGS and it is 

operated by the DGS. The ESIC provides 

information on cartography, geography, 

digital data, remote sensing, geology, 

geophysics, geochemistry, hydrology, 

geohydrology, aerial photography, and 

land use. It is supported by the USGS 

with reference materials, technical assistance, training, outreach activities, and 

access to USGS data bases.

Metallic Mineral-Resource 

Assessment

Economic growth and development 

in Delaware depend in part on the availability of local sources of minerals for 

use in industry, manufacturing, and the 

maintenance and upgrading of the 

region’s infrastructure. The USGS, in 

conjunction with the State Geological 

Surveys and resource agencies including 

the DGS, is inventorying known mineral 

resources and assessing the potential for 

as-yet undiscovered mineral resources, 

based on geological, geophysical, and 

geochemical studies. Information in digital and paper form will assist Federal 

and State land management agencies, 

regional planners, industry, and local 

governments in ensuring adequate supplies of minerals at the lowest possible 

cost and promoting sound management 

of the region’s mineral resources.

Cooperative Programs

USGS activities in Delaware that are 

conducted in cooperation with other agencies include water-resources data collection and interpretive studies of water 

availability and quality. Projects have 

included assessment of ground-water flow 

and quantity using ground-water-flow 

models of surficial, confined, and fractured rock aquifer systems; assessments 

of water quality with respect to brackishwater intrusion; studies of the effects of 

different land uses on water quality in the 

surficial aquifer; studies of the relation of 

wetlands to surface- and ground-water 

quality; and documentation of floods.

The DGS is the official point of contact for cooperative programs between 

the USGS and the State of Delaware. 

The USGS cooperates through the DGS 

with many State and local agencies 

throughout Delaware. For information 

on geologic and hydrologic reports published by the State of Delaware and to 

obtain USGS topographic mapping products (including maps, images, and computerized data), contact the Delaware 

Geological Survey, DGS Building, University of Delaware, Newark, Delaware 

19716, (302) 831-2833, or e-mail at 

dgs@mvx.udel.edu.

USGS state representative

1289 McD Drive

Dover, DE 19901

(302) 573-6241

Email: jmdenver@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-008-96