Geohydrologic Foundations for Ecosystem Restoration: Support for Traveltime and Modeling Studies of Base-Flow Nutrient Loads in Mid-Atlantic Coastal Plain Watersheds

WRD PROJECT #: MD171
PROJECT CHIEF: Krantz, David E.
BEGIN DATE: 01-October-1997
END DATE: 30-September-2000

Customers currently supporting the project:

U.S. Environmental Protection Agency

Problem

Considerable hydrogeologic information about the Chesterville Branch and Morgan Creek watersheds is already known. A basic assessment of Groundwater flow patterns and chemical quality of the Groundwater was presented by Hamilton and others (1993). An early application of the use of chloroflourocarbons (CFCs) as age-dating tracers was made in the Chesterville Branch watershed by Dunkle and others (1993). Reilly and others (1994) used CFC age dates as a tool to help calibrate a 2- dimensional finite-difference cross-sectional model of Groundwater flow in the Chesterville Branch Basin. Bohlke and Denver (1995) used geologic information, age dates, and isotopic data to asses differences in nitrate concentrations in Morgan Creek and Chesterville Branch. They hypothesized that Groundwater discharge in Morgan Creek associated with the marine Monmouth Formation contained evidence of denitrification, whereas Groundwater discharge in Chesterville Branch, associated with the surficial aquifer, did not show evidence of denitrification. However, the available geological data are not sufficient to determine whether flow through the Monmouth Formation favors denitrification because of poor permeability, high organic content of the deposits, or a mineralogy that favors denitrification.

Objectives

Provide better resolution of the geometry of the aquifers and confining layers and provide more information about the physical, mineralogical, and chemical composition of the aquifers and confining layers.

Approach

Under this agreement, the USGS will conduct geologic and hydrochemical studies in the Chester River watershed. During the first year, data will be collected and preliminary interpretations will be made. During the second year, some additional samples may be collected and archived samples may be analysed to answer specific questions that cannot be answered by the data from the first year. One to two technical reports will also be prepared the .second year. These will be published by the Environmental Protection Agency under joint USGS-EPA authorship.