WA

61

OR

40

NV

31

CA

45

AZ

60

ID

96

UT

56 CO

22

WY 57

MT

52 ND

57

SD

70

NE

87

KS

51

OK

34

TX

45 LA

61

AR

53

MO

54

IA

78

MN

80 WI 70

IL

33 IN

64

OH

46

PA

41

WV 43 VA

34

NC

50 SC

45 GA

41 AL

52

FL

93

KY

24 TN

47

MS

92

MI

46

NY

35

ME

60

VT

64

NH

61

MA

46

RI

26

CT

N 54 J

53

DE MD 66 31

AK

62 HI

94 PR

25 VI

7

NM

90

EXPLANATION

60 Estimated percentage of

population using ground

water as drinking water in 1995

Following the Report to Congress, the National Research

Council (NRC) conducted an evaluation of the Ground-Water

Resources Program and, in November 2000, presented their

findings in a report titled “Investigating Groundwater Systems on

Regional and National Scales.” Based on the report to Congress

and the NRC findings, the following seven scientific issues have

been identified as high priority for the Ground-Water Resources

Program.

1) Support for Aquifer Management Decisions−As pumping

and other stresses placed on our ground-water resources intensify,

new approaches being used to optimize ground-water extraction

while limiting undesirable effects such as depletion of groundwater reserves, land subsidence, and harm to ecosystems.

Innovations in artificial recharge, water reuse, and conjunctive use

of ground-water and surface-water resources are leading to new

challenges for USGS scientists to provide the data analyses, and

predictive tools to support sound aquifer management decisions.

2) Natural Ground-Water Recharge−Information about the

amount of water entering (recharging) the Nation's aquifers is

vital, but the recharge rates are difficult to quantify. Improved

knowledge of recharge processes, development and testing of new

recharge estimation techniques, and methods to scale up sitespecific recharge estimates to regional values are needed.

3) Ground-Water Flow in Shallow Aquifers−Ground water is

pumped from shallow aquifers to supply water to homeowners

with private wells, some municipalities, and agricultural users

throughout much of the United States. These shallow aquifers are

particularly vulnerable to contamination from human activities and

sensitive to droughts and climate change.

4) Saltwater Intrusion−Ground-water pumping has caused

saltwater intrusion in the majority of U.S. coastal States, as well as

some inland areas. As coastal cities grow, this problem is likely to

become increasingly important.

Ground water is among the Nation's most important natural

resources. It provides drinking water to urban and rural

communities, supports irrigation and industry, sustains the flow of

streams and rivers, and maintains riparian and wetland

ecosystems. In many areas of the Nation, the future sustainability

of ground-water resources is at risk from over use and

contamination. Because ground-water systems typically respond

slowly to human actions and climate variability, a long-term

perspective is needed to manage this valuable resource. The U.S.

Geological Survey Ground-Water Resources Program provides

regional evaluations, fundamental data, and predictive tools to

help assure the sustainability of our Nation's ground-water

resources.

Priorities for Regional Ground-Water Evaluations

Many ground-water systems extend across county, State, or

other political boundaries. Despite this fact and the national

importance of ground water, there is little ongoing assessment of

ground-water resources availability at regional and national scales

(National Research Council, 2000).

From 1978 to 1995, the U.S. Geological Survey (USGS)

developed quantitative assessments of 25 of the Nation's most

important regional aquifer systems, as part of the Regional

Aquifer-System Analysis (RASA) Program. Most of the RASA

assessments are 10 to 20 years old, and ground-water issues have

increased in scope as competing demands on the resource have

grown.

Concerns by Congress about declining efforts to evaluate the

Nation's principal aquifers led to a 1998 USGS Report to

Congress that outlines a strategy for addressing key regional

issues about the Nation's aquifers, including the effects of lowered

water levels and reductions in ground-water storage, saltwater

intrusion, land subsidence, and reduced ground-water discharge to

streams.

Estimated percentage of population using ground water in each State,

Puerto Rico, and the U.S. Virgin Islands

U.S. Department of Interior

U.S. Geological Survey

U.S. Geological Survey Ground-Water Resources Program, 2001

50

100

150

1930 1940 1950 1960 1970 1980 1990 1995

GROUND-WATER LEVEL,

IN FEET BELOW

LAND SURFACE Ground-water level declines caused by pumping,

Memphis, Tennessee

Ground-Water Level

USGS Fact Sheet 056-01

June 2001
5) Ground-Water and Surface-Water Interaction−It is now

recognized that nearly all surface-water features (streams, lakes,

reservoirs, wetlands, and estuaries) interact with ground water. A

fundamental understanding of these interactions is needed to

evaluate their effects on water availability and the environment and

to support watershed planning and management.

6) Ground Water in Karst and Fractured-Rock Aquifers−New

methods are needed to help understand ground-water flow in karst

and fractured-bedrock aquifers, which are the principal aquifers in

many parts of the Nation. Many ground-water issues are amplified

in fractured-rock aquifers because responses to pumping stresses

and contamination can be more rapid than in aquifers where water

flows through material such as sand and gravel.

7) Improved Hydrogeologic Frameworks−Ground-water

movement is affected to a large degree by the properties of the

rocks and soils through which the water flows. More maps that

accurately show the geology in three-dimensions, as well as

improved conceptual and statistical models of the geologic

framework of aquifers, are needed to adequately assess groundwater resources and determine the effects of ground-water

withdrawals.

New Models, Field Techniques, and Data for Ground-Water

Evaluations

Evaluation of the issues listed above will require new methods

of collecting and analyzing ground-water data. Government

agencies, institutions, and private companies around the world use

models developed by the USGS for simulating ground-water flow

and contamination. As computer technology improves and new

issues emerge, improvements are needed to better integrate models

with advanced geographic information systems and hydrogeologic

data bases.

“...hydrogeologists in WRD were largely responsible for the

development, testing, and widespread application of numerical

models of groundwater flow and contamination in the 1970-1980s.

Their work has disseminated into the private sector and provides

one of the best examples of the USGS's innovations bearing fruit

in the private sector...The USGS is in an excellent position to

manage true integration in the application of environmental

models.” (National Research Council, 2001)

Development of new field techniques also continues to be a

high priority of the program. These techniques include geophysical

methods for ground-water studies and ground-water age-dating

methods to determine aquifer properties and to understand the

interaction of ground water and surface water.

Comprehensive, long-term data bases are needed to support

management of the Nation's resources for ground-water. Datarelated priorities for the Ground-Water Resources Program include

1) improved water-level monitoring of major aquifers, 2) greater

access to ground-water data through the Internet, and 3)

development of systems for storage and presentation of the threedimensional extent of aquifers and their hydrologic characteristics.

USGS hydrologist demonstrates

collection

of ground-water data

U.S. Department of Interior

U.S. Geological Survey

USGS Fact Sheet 056-01

June 2001

Enhanced Program Activities

Congress provided additional funding for the Ground-Water

Resources Program in fiscal year 2001 to begin to address some of

the high-priority ground-water issues. This additional funding is

supporting the following activities across the Nation.

Norman G. Grannemann

References

National Research Council, 2000, Investigating groundwater systems

on regional and national scales: Washington, D.C., National

Academy Press, 143 p.

National Research Council, 2001, Future roles and opportunities for

the U.S. Geological Survey: Washington, D.C., National Academy

Press, 179 p.

For additional information about

the USGS Ground-Water Resources Program,

please see http://water.usgs.gov/ogw/

or contact:

Chief, Office of Ground Water

U.S. Geological Survey

411 National Center

12201 Sunrise Valley Drive

Reston, VA 20192

Hydrogeologic characterization of alluvial basins in the arid Southwest

Assessment of ground-water and surface-water interaction related to

irrigation in the Methow Valley, Washington

Development and testing of new geophysical methods for monitoring

saltwater intrusion and ground-water discharge to coastal bays in

Massachusetts, Maryland, and Delaware

Data collection and model development for saltwater intrusion in

Virginia, North and South Carolina, Georgia, and Florida

Fractured-rock aquifer analysis and related geologic mapping in

Connecticut

Studies of ground-water depletion and water use for the High Plains

Aquifer in Wyoming, South Dakota, Colorado, Nebraska, Kansas,

Oklahoma, Texas, and New Mexico

Analysis of ground-water and surface-water interaction in Indiana and

Michigan using new three dimensional geologic maps from the Central

Great Lakes Geologic Mapping Coalition

Evaluation of the importance of microbiological processes related to

regional ground-water-flow systems, especially for karst aquifers

Overview of water issues for caves and springs in the Nation's parks

Improved estimation of recharge rates in the eastern United States