Using altitudes of the water table at individual wells on Long Island

Using known altitudes of the water table at individual wells (A), contour maps of the water-table surface can be drawn (B), and directions of ground-water flow along the water table can be determined (C) because flow usually is approximately perpendicular to the contours. Groundwater moves along flow paths of varying lengths in transmitting water from areas of recharge to areas of discharge (Winter and others, 1998).