Water Quality in the Delmarva Peninsula

Delaware, Maryland, and Virginia, 1999-2001


U.S. Geological Survey Circular 1228


By Judith M. Denver, Scott W. Ator, Linda M. Debrewer, Matthew J. Ferrari, Jeffrey R. Barbaro, Tracy C. Hancock, Michael J. Brayton, and Mark R. Nardi


This circular is available as a pdf.


This report contains the major findings of a 1999-2001 assessment of water quality in the Delmarva Peninsula. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation.


In these reports, water quality is assessed at many scales—from local ground-water flow paths to regional ground-water networks and in surface water—and is discussed in terms of local, State, and regional issues. Conditions in the Delmarva Peninsula are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms.


This report is intended for individuals working with water-resource issues in Federal, State, or local agencies; universities; public interest groups; or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams and ground water in areas near where they live, and how that water quality compares to the quality of water in other areas across the Nation.


Other products describing water-quality conditions in the Delmarva Peninsula are available. Detailed technical information, data and analyses, methodology, models, graphs, and maps that support the findings presented in this report can be accessed from Other reports in this series and data collected from other basins can be accessed from the national NAWQA Web site (


National Water-Quality Assessment Program

What kind of water-quality information does the NAWQA Program provide?

Introduction to this Report

Summary of Major Findings

Stream and River Highlights

Ground-Water Highlights

Introduction to the Delmarva Peninsula

Land Use

Hydrogeology and Water Use

Ground-Water Quality

Surface-Water Quality

Major Findings

Nutrients in Ground Water and Streams

Nitrate is widespread in the surficial aquifer, including deeper parts used for drinking water

Nutrient concentrations in streams reflect human sources

NATIONAL PERSPECTIVE—Nutrient concentrations on the Delmarva Peninsula are among the Nation's highest

Pesticides in Ground Water and Streams

Herbicides are frequently detected in the surficial aquifer

What is a pesticide degradate?

Pesticides are commonly detected in streams

Delmarva Peninsula NAWQA study contributes to understanding of water quality in the Chesapeake Bay

NATIONAL PERSPECTIVE—Herbicide concentrations in streams and ground water in agricultural areas on the Delmarva Peninsula are similar to those in other intensively farmed areas where corn and soybeans are grown

Other Ground-Water Quality Issues

Volatile organic compounds are detected in ground water

Radon occurs in water throughout the surficial aquifer

Dissolved iron is present in ground water from poorly drained areas

Arsenic is common in ground water at low concentrations

Reconnaissance for Arsenic in a Poultry-Dominated Basin on the Delmarva Peninsula

Study Unit Design

References Cited


Appendix—Water-Quality Data from the Delmarva Peninsula in a National Context

Points of Contact and Additional Information

The companion Web site for NAWQA summary reports:


Delmarva Peninsula contact and Web site:

USGS State Representative

U.S. Geological Survey

Water Resources Discipline

1289 McD DriveDover, DE 19901


National NAWQA Program:

Chief, NAWQA Program
U.S. Geological Survey
Water Resources Discipline
12201 Sunrise Valley Drive, M.S. 413
Reston, VA 20192


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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:


The full report is available in pdf format and is 22.2 MB in size.


If you have Adobe® Acrobat® or Adobe® Acrobat® Reader® installed on your computer, you may view and print the PDF version of this report. Acrobat Reader, is a free download it from Adobe Systems, Inc.  Users with disabilities can view information concerning accessibility at


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