Traditionally, management of water resources has focused on surface water or ground water as if they were
separate entities. As development of land and water resources increases, it is apparent that development of either of
these resources affects the quantity and quality of the other. Nearly all surface-water features (streams, lakes, reservoirs,
wetlands, and estuaries) interact with ground water. These interactions take many forms. In many situations,
surface-water bodies gain water and solutes from ground-water systems and in others the surface-water body is a
source of ground-water recharge and causes changes in ground-water quality. As a result, withdrawal of water from
streams can deplete ground water or conversely, pumpage of ground water can deplete water in streams, lakes, or
wetlands. Pollution of surface water can cause degradation of ground-water quality and conversely pollution
of ground water can degrade surface water. Thus, effective land and water management requires a
clear understanding of the linkages between ground water and surface water as it applies to any given hydrologic
setting.
This Circular presents an overview of current understanding of the interaction of ground water and surface
water, in terms of both quantity and quality, as applied to a variety of landscapes across the Nation. This Circular is a
product of the Ground-Water Resources Program of the U.S. Geological Survey. It serves as a general educational
document rather than a report of new scientific findings. Its intent is to help other Federal, State, and local agencies
build a firm scientific foundation for policies governing the management and protection of aquifers and watersheds.
Effective policies and management practices must be built on a foundation that recognizes that surface water and
ground water are simply two manifestations of a single integrated resource. It is our hope that this Circular will
contribute to the use of such effective policies and management practices.