As development of land and water resources intensifies, it is increasingly apparent that development of either ground water or surface water affects the other.
Many streams do both, gaining in some reaches and losing in other reaches.
Under natural conditions, ground water makes some contribution to streamflow in most physiographic and climatic settings. Thus, even in settings where streams are primarily losing water to ground water, certain reaches may receive ground-water inflow during some seasons. An important feature of streams that are disconnected from ground water is that pumping of ground water near the stream does not affect the flow of the stream near the pumped well. Interaction of streams and ground water. For ground water to discharge to a stream channel, the altitude of the water table in the vicinity of the stream must be higher than the altitude of the stream-water surface.