Importance of Ground Water in the

Atlantic Coastal Plain of Maryland

Ground water is the primary source

of water supply in most areas of

Maryland within the Atlantic Coastal Plain

(fig. 1), and is pumped from sand and gravel

layers underlying the Coastal Plain. These

sand and gravel layers alternate with layers

of silt and clay to form a wedge-shaped

system of sediments that begins at the Fall

Line (the boundary between the Atlantic

Coastal Plain and the Piedmont

Physiographic Provinces) and gently tilts

and thickens to the southeast toward the

Atlantic Ocean (fig. 2). The buried sands

and gravels form a sequence of confined

aquifers that is overlain by sandy deposits

that form a surficial aquifer. These aquifers

are the primary water supply for southern

Maryland and the Eastern Shore.

Why is this Assessment Necessary?

1) Water Levels in the Aquifers are

....Declining at a Significant Rate

Withdrawals from Maryland Coastal

Plain aquifers have caused ground-water

levels in confined aquifers to

decline by tens to hundreds of

feet from their original levels (fig.

3). The current rate of decline in

many of the confined aquifers is

about 2 feet per year. The

declines are especially large in

southern Maryland and parts of

the Eastern Shore, where

ground-water pumpage is projected to increase by more than

20 percent between the years

2000 and 2030, with some regions

experiencing significantly greater

increases. Continued water-level

declines at current rates could

affect the long-term sustainability

of ground-water resources in

Maryland’s heavily populated

Coastal Plain communities and

the agricultural areas of the

Eastern Shore. 

2) Water Quality in Some Areas

....is Significantly Compromised 

Water quality in the Coastal

Plain aquifers is a concern for

several reasons. Contamination

by saltwater intrusion is a significant waterquality issue for the confined

aquifers, and has been documented

in several of Maryland’s waterfront

communities. However, the potential for saltwater intrusion is not well

known in the deeper parts of the

aquifer system because few data

are available. Some areas have

problems with naturally high concentrations of trace-element contaminants (including arsenic and

radium), and further evaluation of

these public health issues is warranted. Elevated concentrations of

nutrients and agricultural chemicals

in the surficial aquifer is a significant concern, especially on the

Eastern Shore, where shallow

ground water is the water-supply source

for many homeowners and provides much

of the base flow to streams. 

3) Ground-Water Resource Managers Need

....Better Tools 

Water managers, policymakers, planners, and developers need to know how

much ground water is available in the different areas of the Maryland Coastal Plain

for public and domestic water supply, agriculture, industry, and electric power generation. Ground-water withdrawals in

Maryland are managed by the Maryland

Department of the Environment (MDE)

through the Water Appropriations Permit

Program. While studies of individual

aquifers or multi-aquifer subregions are

available, MDE needs more comprehensive

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet FS 2006-3009

2006
and interactive tools for making management and permitting decisions. Specifically,

MDE needs information systems and simulation tools to evaluate the effects of

increased withdrawals on the entire aquifer

system in important subregions and

throughout the Maryland Coastal Plain.

These tools need to take into account that

some of the aquifers are units of a regional

system that extends into and is used for

water supply in adjacent states. 

Evaluation of alternative water-management strategies requires enhancements

in the monitoring networks for groundwater levels and streamflow throughout the

Coastal Plain. Water managers and planners need to understand where and when

continued withdrawal of ground water may

reduce streamflow and/or induce changes

in water quality that would require additional treatment or limit uses of the water

resource. 

Plans for the Comprehensive

Assessment of the Coastal Plain

Aquifer System in Maryland 

In response to the Advisory

Committee’s 2004 report recommendations,

MGS and USGS are preparing a science

plan and implementation plans for conducting a comprehensive regional assessment

of the Coastal Plain aquifers in Maryland

and appropriate areas of surrounding

states.

Comprehensive Assessment is

Underway

MGS and USGS started Phase I of the

Comprehensive Assessment in January

2006. Phase I activities are being jointly

supported by funds and services from MDE,

MGS, and USGS. Phases II and III of the

assessment will require significant additional investment from current and new

funding partners from 2008 to 2013.