Groundwater affected by development, scientists say


Groundwater is both the source of drinking water and the method of disposing of wastewater, said Scott Andres, hydrogeologist with the Delaware Geological Survey. There is plenty of water to be had, he said, but the challenge is protecting public and environmental health.

RI72 Geology and Extent of the Confined Aquifers of Kent County, Delaware

Ground water comprises nearly all of the water supply in Kent County, Delaware. The confined aquifers of the area are an important part of this resource base. The aim of this study is to provide an up-to-date geologic framework for the confined aquifers of Kent County, with a focus on their stratigraphy and correlation. Seven confined aquifers are used for water supply in Kent County. All occur at progressively greater depths south-southeastward, paralleling the overall dip of the sedimentary section that underlies the state.

RI70 Thickness and Transmissivity of the Unconfined Aquifer of Eastern Sussex County, Delaware

The unconfined portion of the Columbia aquifer is a key hydrologic unit in Delaware, supplying water to many agricultural, domestic, industrial, public, and irrigation wells. The aquifer is recharged through infiltration of precipitation and is the source of fair-weather stream flow and water in deeper confined aquifers. The aquifer occurs in permeable sediments ranging in age from Miocene to Recent. Over most of Delaware, the top of the unconfined or water-table portion of the Columbia aquifer occurs at depths less than 10 feet below land surface.

RI67 The Cat Hill Formation and Bethany Formation of Delaware

Because of the rapid development occurring in coastal Delaware and the importance of ground water to the economy of the area, definition of formal lithostratigraphic units hosting aquifers and confining beds serves a useful purpose for resource managers, researchers, and consultants working in the area. The Pocomoke and Manokin are artesian aquifers pumped by hundreds of domestic and dozens of public wells along the Atlantic coast in Delaware and Maryland. These aquifers are being increasingly used for public water supply.

RI64 Results of Hydrogeologic Studies of the Cypress Swamp Formation, Delaware

The Cypress Swamp Formation is the surficial geologic unit in south-central Sussex County, Delaware. Detailed hydrologic observations made as part of four separate studies between 1995 and 1999 show that the Cypress Swamp Formation consists of a complex assemblage of moderately permeable sands and low permeability organic and inorganic silts and clays that form a heterogeneous shallow subsurface hydrologic system that is between about 5 and 15 feet thick. Aquifer tests show that hydraulic conductivity ranges between 0.55 and 40 ft/day, with an arithmetic mean of 13 feet/day.

RI57 Evaluation of the Stream-Gaging Network in Delaware

The stream-gaging network in Delaware is a major component of many types of hydrologic investigations. To ensure that the network is adequate for meeting multiple data needs by a variety of users, it must represent the range of hydrologic conditions and land-use types found in Delaware, and include enough stations to account for hydrologic variability. This report describes the current stream-gaging network in Delaware and provides an evaluation of its representativeness for the State.

RI49 Results of the Coastal Sussex County, Delaware Ground-Water Quality Survey

The results of this investigation of the Columbia aquifer in coastal Sussex County, Delaware, provide some of the data necessary to evaluate the condition of the area's primary source of fresh water. Chemical analyses of water samples from domestic, agricultural, public, and monitoring wells document the effects of past and present land use practices. Groundwater flow paths and flow systems are inferred from flow-net analysis, ground-water chemistry, and isotopic composition.