Viral Contamination of the Shallow Ground Water in Wicomico and Worcester Counties, Maryland

WRD PROJECT #: MD119
PROJECT CHIEF: Banks, William S.L.
BEGIN DATE: 01-July-1998
END DATE: 31-December-2000

Customers currently supporting the project:

Maryland Department of the Environment
U.S. Geological Survey

Problem

In response to the 1996 Amendments to the Safe Drinking Water Act, the U.S. Environmental Protection Agency (USEPA) is developing the Ground Water Rule (GWR) to protect users of public-ground water supplies from viral contamination. Many ground-water suppliers do not currently practice any form of disinfection treatment, as monitoring of their water supply has not detected coliform microorganisms. Because of difficulties associated with monitoring directly for viral contamination, it has not been possible to routinely identify whether viruses are present in water supplies. Therefore, studies are needed to characterize the true extent of viral pollution in ground water used for drinking throughout the United States.

Objectives

The objective of this study is to identify recharge areas for public-supply wells using less than 10,000 gallons per day in the shallow surficial aquifer in selected parts of Wicomico and Worcester Counties, and to determine their sensitivity to viral contamination. Additionally, microbiological indicators will be evaluated regarding their usefulness as surrogates for determining viral contamination.

Approach

Initially, a conceptual ground-water flowpath model will be used to determine susceptibility of transient and non-transient community water-supply wells to viral contamination. This conceptualization will be used to guide the selection of a subset of approximately 25 wells that may be vulnerable to microbiological contamination from sources of waterborne viruses. Five wells not believed to be susceptible will also be sampled for control and comparison. Samples will be collected and analyzed for viruses, microbiological indicators, and other chemical constituents. Results of the sampling will be used to characterize the extent of viral contamination of the shallow surficial aquifer. An interpretive report will subsequently be published.